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  Current Issue
 
2023 Vol.43 Issue.8,Published 2023-08-20
Air Pollution Control
Water Pollution Control
Solid Waste
Soil Pollution Control
Environmental Ecology
Carbon Emission Control
Emerging Contaminants and Environmental Toxicology
Air Pollution Control
3857 Source apportionment of atmospheric volatile organic compounds in summer and autumn in Shenzhen industrial area
ZHANG Yue, XIA Shi-yong, WEI Cheng-bo, LIU Shi-qi, CAO Li-ming, YU Guang-he, HUANG Xiao-feng
The long-term online observation of atmospheric volatile organic compounds (VOCs) was carried out in the northern industrial area of Shenzhen from July to October 2021 to analyze pollution characteristics of VOCs during ozone polluted days and non-polluted days. The refined source apportionment of VOCs was carried out by using ratio method of characteristics species and positive matrix factorization (PMF) model to analyze the concentration and OFP contribution of each emission source and the influence of meteorological conditions. The results showed that the average mixing ratio of TVOCs was 50.48×10-9, of which alkane contributed the most, followed by OVOCs and aromatic, accounting for 41.3%, 22.2% and 17.0% respectively. Comparing with non-polluted days, the mixing ratio of OVOCs increased the most during polluted days (63.1%). The ratio of characteristic species indicated that the area was mainly affected by vehicle emission and industrial solvent use. Five VOCs emission sources were determined by the PMF model, of which vehicle emissions and gasoline volatilization contributed the most to the concentration (28.2%), followed by solvent use (22.9%), process emissions (25.0%) and biomass combustion (20.4%). OFP contribution of process emissions and solvent use exceeded 70% during polluted days. The distribution characteristics with wind speed and direction indicated that vehicle emissions and gasoline volatilization, process emissions and solvent use mainly came from local emissions, while biomass combustion was more influenced by transmission from northeast. It is suggested to intensify local industrial and traffic source controls, while also paying attention to biomass combustion and strengthening joint prevention and control with neighboring areas.
2023 Vol. 43 (8): 3857-3866 [Abstract] ( 310 ) [HTML 1KB] [ PDF 1597KB] ( 1609 )
3867 Four seasons pollution characteristics and source analysis of atmospheric formaldehyde in Shenzhen
HAN Heng-xiao, XIA Shi-yong, LUO Yao, CAO Li-ming, PENG Xing, HUANG Xiao-feng, HE Ling-yan
Four seasons online observation of atmospheric formaldehyde (HCHO) and other photochemical pollutants was carried out in a western urban site of Shenzhen in 2022, with the aim of analyzing the atmospheric HCHO pollution and its relationship with meteorological factors as well as identifying the main sources of HCHO by feature ratio method and principal component analysis (PCA). During sampling, the average mixing ratio of HCHO showed the highest in winter (3.67×10-9), followed by autumn (3.29×10-9), summer (2.39×10-9) and spring (2.25×10-9), and the diurnal variation of HCHO, O3 and PAN in four seasons all presented a "diurnal single peak" feature. High temperature (>25℃) and strong solar radiation (5.5×10-3<JNO2<7.5×10-3) could promote the formation of HCHO, while high relative humidity could accelerate the wet deposition of HCHO. There was a significant positive correlation between HCHO and O3 in summer and autumn during daytime (r>0.90), while the correlation between HCHO and NOx was not obvious, indicating the secondary generation property of HCHO during the photochemical active period in Shenzhen. The concentration ratio of formaldehyde to acetaldehyde (C1/C2) in autumn was the highest (3.1±0.9), followed by that in summer (2.9±1.5) and spring (2.3±0.9), with the lowest in winter (1.7±0.7). The higher C1/C2 in summer and autumn indicated that HCHO was significantly affected by photochemical oxidation at this time. The results of principal component analysis showed that the main sources of daytime HCHO in four seasons were secondary formation sources (40.2%), biogenic sources (31.6%) and anthropogenic primary emissions (14.5%), among which secondary formation sources and biogenic sources contributed significantly higher in summer and autumn than that in winter and spring, while the contributions of anthropogenic primary sources in winter and spring were twice those in summer and autumn.
2023 Vol. 43 (8): 3867-3876 [Abstract] ( 191 ) [HTML 1KB] [ PDF 2589KB] ( 1584 )
3877 Observation of partitioning characteristics of gaseous nitric acid in winter of Shenzhen
LUO Yao, LIN Xiao-yu, NIU Ying-bo, YUN Long, GU Tian-fa, LIN Chu-xiong, HUANG Xiao-feng, HE Ling-yan
The particle phase fraction of total nitrate determines its lifetime in the atmosphere, but this distribution process in urban areas in winter remain poorly understood. In this study, concentrations of HNO3, NO3- and related pollutants was online observed at two sites (urban site and roadside site) in Shenzhen from January 1to January 31, 2022. During the observation period, the average concentration of NO3- was (6.3±3.9) μg/m3, accounting for 24.7% of the mass concentration of PM2.5, which is one of the most important components of PM2.5 in winter in Shenzhen. The mean values of ε(NO3-) at two sites were (0.81±0.13) and (0.75±0.16), respectively, and the distribution of nitrate was mainly to the particle phase. ε(NO3-) reflected the gas-particle partitioning of nitrate, and it was higher during nighttime and lower during daytime. The higher temperature, lower humidity and more acidic environment would enhance nitrate volatilization and its partitioning to gas phase, thus driving the diurnal variation of ε(NO3-). In addition, aerosol liquid water content and aerosol pH were the most important factors affecting the difference of two-site ε(NO3-) in winter of Shenzhen, with average contribution of 41% and 31%, respectively, indicating that these two factors should be taken into consideration when modeling the formation and transformation of gaseous nitric acid.
2023 Vol. 43 (8): 3877-3885 [Abstract] ( 234 ) [HTML 1KB] [ PDF 938KB] ( 1303 )
3886 Comparison of estimation models for near-surface ozone concentration based on gradient boosting algorithm
LIANG Xiao-xia, XIE Dong-hai, HAN Zong-fu, SONG Shi-peng, ZHANG Xin-xin, GU Jian-bin, YU Chao
This paper proposes an improved model for estimating the temporal and spatial distribution of near-surface ozone conc­entrations based on the gradient boosting tree optimization algorithm. First, in-situ near-surface O3 concentrations data, high-resolution satellite observations of atmospheric compositions (TROPOMI, AIRS), ERA5meteorological reanalysis data, and land cover and terrain data were used to investigate thecorrelations among O3, tropospheric O3, O3 precursors, meteorological factors and underlying surfaces in the Beijing-Tianjin-Hebei region. Then, estimation models for near-surface O3 concentrations based on three different gradient boosting tree algorithm models (GBDT, XGBoost, LightGBM) were developed, and the estimation accuracies of different models were compared and analyzed. Results showed that all three models could accurately estimate near-surface ozone concentrations, with the XGBoost model demonstrating the highest accuracy. The coefficients of determination R2 of GBDT, XGBoost, and LightGBM were 0.9489, 0.9547, and 0.9495 respectively, and the root mean square errors RMSE were 13.85μg/m3, 13.26μg/m3 and 13.76μg/m3 respectively. Using filtering methods, correlation analysis, and recursive feature elimination, the XGBoost estimation model was optimized, feature complexity was reduced while maintaining model accuracy. After optimization, the estimation accuracy of the optimized model reached R2=0.9549, increasing the estimation efficiency by about 17%. This paper provided a sophisticated and efficient method for modeling and estimating the temporal and spatial distribution of ozone concentration on a regional scale.
2023 Vol. 43 (8): 3886-3899 [Abstract] ( 243 ) [HTML 1KB] [ PDF 9294KB] ( 1777 )
3900 Spatial distribution, photo-production and flux of Hydrogen in the East China Sea in autumn
JIANG Yu-cheng, XU Gao-bin, ZHOU Li-min, ZHANG Hong-hai
The spatial distribution, photo-production rate and sea-to-air flux of hydrogen (H2) were investigated in the East China Sea in October, 2021. The concentration of H2 in the surface seawater ranged from 2.94 to 7.67nmol/L, with a mean of value (4.82 ±1.12) nmol/L. As the vertical distribution of H2, the higher concentrations appeared at the bottom (11.86nmol/L) which attributed to the release from sediment, as an important source of H2 in the bottom seawater, according to the sediment incubation experiment. The photo-productionrates varied between 0.42 and 1.14nmol/(L·h), with an average of (0.72 ±0.25) nmol/L. The ratio of the quotient of H2 photo-production rates and cumulative photon flux under UV and PAR was 33:1. In addition, the saturation factors of H2 ranged from 7.14 to 24.37, suggesting the concentrations of H2 were oversaturated in seawater. The sea-to-air fluxes of H2 were estimated to be from 0.53 to 9.19 μmol/(m2·d), with a meanof (3.50 ±1.86) μmol/(m2·d), which indicated that the East China Sea is the net source of atmospheric H2.
2023 Vol. 43 (8): 3900-3908 [Abstract] ( 250 ) [HTML 1KB] [ PDF 2992KB] ( 1533 )
Water Pollution Control
3909 Water purification by combined process of KMnO4-PAC-ceramic membrane filtration
YU Hong-jiian, LI Xiao-sa, LI Tian, DONG Bing-zhi, XIA Sheng-ji
Submerged flat sheet ceramic ultrafiltration membrane (CUF) was used to filtrate water samples with model foulants of humic acid (HA), bovine serum albumin (BSA) and sodium alginate (SA) under the constant flux of 120L/(m2·h), with the pretreatment methods of KMnO4 pre-oxidation, activated carbon (PAC) adsorption and the combined process. The effect on the removal of DOC and the integral standard volume of the model pollutants in the fluorescence area, and the membrane filtration enhancement on the fouling related indicators (specific transmembrane pressure difference, membrane fouling index, membrane filtration resistance, etc.) were investigated. The combined KMnO4-PAC-ceramic membrane filtration process had the best removal performance on the three model pollutants of HA, BSA and SA, with the DOC removal ratios of 50.9%, 61.0% and 94.2%, respectively. In terms of membrane fouling control, compared with individual KMnO4 pre-oxidation or PAC adsorption, the combined KMnO4-PAC pretreatment process exhibited higher membrane fouling control efficiency, with fouling rates of 13.0%, 28.0% and 4.5% for HA, BSA and SA, respectively. In addition, the combined KMnO4-PAC pretreatment process could effectively alleviate the reversible membrane fouling in the filtration of BSA and SA, with the decrease ratios of reversible filtration resistance of 20.5% and 21.4%, respectively, thus to better reduce membrane fouling.
2023 Vol. 43 (8): 3909-3917 [Abstract] ( 214 ) [HTML 1KB] [ PDF 978KB] ( 1832 )
3918 Effects of drought duration on the denitrification of biofilms in intermittent river
MIAO Ling-zhan, LI Wei-yu
This study took the biofilms cultivated in artificially simulated rivers as the test subjects, and explored the dynamic response of biofilms denitrification to rewetting process after short-term drought (25days) and long-term drought (90days). The results showed that the water content and macro-microscopic morphology of biofilm changed significantly during both drought and rewetting, and the water content dropped sharply in the 3d to 7d, from (74.96±3.57)% to (2.38±0.37)%. The denitrification rate of both short and long term drought groups showed a continuous increase after rewetting. The short-term drought group showed a significant increase (P<0.05), from (3.26±0.12) to (5.35±1.18)μmol N2-15N/(L·h), while the long-term drought group was concentrated in the late rewetting period, from (2.14±0.19) to (4.15±0.89)μmol N2-15N/(L·h) (P <0.05). Biofilms that experienced short-term drought were able to recover to the initial denitrification rate level through the rewetting process, while those that experienced long-term drought had difficulty achieving it (P<0.05), indicating that long-term drought had an irreversible effect on the denitrification rate of biofilm. The activities of denitrification functional enzymes also showed different changes during each rehydration stage. Short-term drought significantly increased the nitric oxide reductase activity at the end of the reaction pathway (P<0.05). While the nitrite reductase and nitrite oxide reductase, which directly affect the denitrification rate, also had difficulty in recovering to their initial levels after experiencing long-term drought (P<0.05). The above results show that prolonged drought significantly alters the biogeochemical cycle driven by river biofilms (denitrification function).
2023 Vol. 43 (8): 3918-3925 [Abstract] ( 203 ) [HTML 1KB] [ PDF 1082KB] ( 1082 )
3926 Study on anaerobic conversion mechanism of sulfate and ammonia in organic wastewater
REN Hong-li, YUAN Lin-jiang, CHEN Xi
By gradually increasing the influent n(NH4+-N)/n(SO42-) ratio, sulfate reduction-ammonia oxidation (SRAO) was achieved in an up-flow anaerobic sludge blanket (UASB) reator under anaerobic organic conditions (ORP=(-334.3±18.2) mV, DO=(0.10±0.5) mg/L). The effects of different COD on the removel performance of nitrogen and sulfur were studied. The transformation mechanism was discussed by analyzing the SRAO products, the operation results of different stages and the variation of microbal flora. The results showed that the SRAO was that SO42- oxidized NH4+-N to NO2--N and generated S to accumulate in the sludge phase. The intermediate product NO2--N was reduced by autotrophic/heterotrophic denitrifying bacteria, and part of SO42- was reduced to S2- by sulfate reducing bacteria (SRB). Synergistic metabolism among microorganisms achieved simultaneous removal of nitrogen and sulfur in the system. Increasing the influent N/S ratio can make more NH4+-N converted to NO2--N to be utilized by denitrifying bacteria, but when the N/S ratio was increased to 4, the sulfur autotrophic denitrification strongly affected the removal of SO42-, and the abundance of Thiobacillus in the reactor increased by 3.36% at this stage. The simultaneous removal of NH4+-N and SO42- did not occur under inorganic conditions without organic matter. Increasing the influent COD concentration to 150mg/L promoted the coupling of SRAO and denitrification, and improved the nitrogen and sulfur removal performance of the system. The total abundance of SRB (Desulfococcus, Desulfatiglans) and various denitrifying bacteria (Methyloversatilis, Longilinea, Simplicispira, Bdellovibrio, Azospira, etc.) in the reactor increased by 1.584% and 6.081%, respectively. When COD=250mg/L, the enhanced sulfated reduction reaction produced more S2-, which inhibited the SRAO activity and affected the removal of NH4+-N in the system.
2023 Vol. 43 (8): 3926-3934 [Abstract] ( 218 ) [HTML 1KB] [ PDF 1290KB] ( 1306 )
3935 Removal and mechanism study of Cr(VI) in water by sludge biochar-supported nano-ferrous sulfide
LYU Si-lu, LIU Tian, WANG Xu, ZUO Kai-xia, XIE Yan-hua
In this study, sludge biochar loaded with nano-sized ferrous sulfide (MBC) was prepared by pyrolyzing the sludge impregnated with Fe3+ and S2- ions. The preparation conditions of MBC and its removal performance on Cr(Ⅵ) were investigated, and the composites before and after reaction were characterized by SEM, TEM, XRD and XPS to explore the removal mechanism. The results show that the pyrolysis temperature (500℃) was relatively low because the presence of Fe3+ and S2- ions. Acidic conditions were beneficial to the Cr(Ⅵ) removal. When the pH was 2~4 and the dosage of MBC was 2.5g/L, the removal rate of 50mg/L Cr(Ⅵ) can reach 99%. Furthermore, the combined process of MBC+NaOH (pH=7.8) can completely remove the total Fe and total Cr in the effluents. The precipitates generated from the combined process were very compact, and the effluents were colorless and transparent. The characterization results showed that nano-sized ferrous sulfide and iron oxide particles were successfully loaded on the sludge biochar and coated on the surface of the material in the form of semi-transparent film. Fe2+, Sn2- and C=O on the MBC could be acted as electron donors to reduce most of Cr(Ⅵ) to form the chelated compounds such as C-O-Cr, C=O-Cr etc. The residual Cr(Ⅵ) in solution can be also adsorbed by the composites. Therefore, the removal mechanism of Cr(Ⅵ) by MBC manly included chemical reduction, complexation, and adsorption, especially reduction played the key role.
2023 Vol. 43 (8): 3935-3945 [Abstract] ( 260 ) [HTML 1KB] [ PDF 1735KB] ( 1878 )
3946 Removal of opportunistic pathogens in secondary effluent from sewage plants by slow filtration
SUN Li-hua, WANG Chun-fang, ZHU Jun-yao, DENG Si
This study investigated the removal of Pseudomonas aeruginosa in secondary effluent from sewage plants, as well as the related mechanism. Different slow filtration parameters influence on Pseudomonas aeruginosa removal such as filtration velocity, carbon nitrogen ratio, ion concentration and pH were examined. The results showed that 87.0% removal of Pseudomonas aeruginosa could be obtained under the optimizing condition with 5cm/h of filtration velocity, 10:1of C/N, 60mg/L of Ca2+ at pH7. And the biofilm on the filter surface had the highest diversity and the most uniform of the species composition under this condition, Anaplasma spp. and Nitrospira spp. accounted for the largest proportion of the relative abundance of microorganisms with removal effect on Pseudomonas aeruginosa. Mechanism study revealed that the deposition of pollutants on the biofilm surface of the filter was mainly attributed to the adhesion of extracellular polymers under 5cm/h of filtration velocity, 10:1of C/N, while the adhesion of microorganisms contributed for the deposition of pollutants under 60mg/L of Ca2+ at pH 7.
2023 Vol. 43 (8): 3946-3955 [Abstract] ( 167 ) [HTML 1KB] [ PDF 1043KB] ( 1564 )
3956 Study on the nitrogen removal ability of vertical flow constructed wetland treating tailwater of sewage plant
HE Qiang, HU Shu-shan, XIANG Ze-yi, ZHU Yue, ZHANG Ling-ling, YANG Yu-jing, CHENG Cheng
Three groups of vertical flow constructed wetlands, filled with coconut fiber and ceramsite (experimental group 1, YTCW), gravel and ceramsite (experimental group 2, LTCW), and gravel quartz sand (control group, CCW), respectively, were employed to treat synthetic tailwater of the sewage plant. Nitrogen pollutants removal efficiency and transformation mechanisms in winter and summer were explored. The higher removal efficiency of ammonium and nitrate, as well as lower emission flux of nitrous oxide, were observed in summer than in winter. In winter, the removal efficiency of ammonia nitrogen increased by 23.8% (YTCW) and 26.9% (LTCW) compared with CCW. Nitrate removal efficiency in the experimental group was 32.2%(YTCW) and 34.0%(LTCW) higher than those in CCW. The average nitrous oxide emission flux in a typical cycle was 0.18mg/(m2·h) (YTCW), 0.03mg/(m2·h) (LTCW) and 1.17mg/(m2·h) (CCW), respectively. The results of high-throughput sequencing showed that the relative abundance of nitrogen removal functional microorganisms was increased in experimental groups than control, which could improve the nitrogen removal efficiency of constructed wetlands under low temperatures.
2023 Vol. 43 (8): 3956-3965 [Abstract] ( 187 ) [HTML 1KB] [ PDF 1629KB] ( 1838 )
3966 Inactivation of E. coli in water by electrochemical activation of peracetic acid
JIANG Li-ming, BIAN Jing, ZHANG Xiao-hui, XIANG Jun-ying, ZHONG Yi-hua, ZHAO Chun
The inactivation of E. coli was studied by introducing electric field to improve the oxidation capacity of peracetic acid. The effects of peracetic dosage, current intensity, initial pH value and water matrix (HA、Cl-、HCO3- and PO43-)on the inactivation of E. coli were investigated respectively. Besides, the active species and the inactivation process of E. coli were systematically analyzed. The electrochemical activation of peracetic acid showed obvious synergistic effect on the inactivation of E. coli. Compared with peracetic acid alone, the inactivation of E. coli increased by 2.24 log within 10min. Increasing the peracetic acid dosage and current intensity could improve the inactivation of E. coli. However, when the current intensity increased to a threshold, the improvement on the inactivation of E. coli was negligible. Acidic conditions facilitated the inactivation of E. coli, and the optimal condition of pH was at 3. Cl- obviously promoted the inactivation of E. coli, while HA、HCO3- and PO43- inhibited the inactivation process. Free radical quenching experiments evidenced that×OH and R-O×existed in the electrochemical activation of peracetic acid, while the×OH played the major role in the inactivation of E. coli. The study of the inactivation mechanism of E. coli revealed that the cell wall and membrane were destroyed at first. Then, the intracellular material flowed out. Eventually, the cells were gradually broken down into fragments and completely inactivated.
2023 Vol. 43 (8): 3966-3973 [Abstract] ( 258 ) [HTML 1KB] [ PDF 1065KB] ( 2256 )
3974 Efficiency and mechanism of fluoride removal by electroadsorption of alumina modified activated carbon fiber
WEI Yong, LI Xian-jian, LUO Zheng-bo, LI Ke-ying, GUO Zi-yin, SHI Rong-kai
The modified electrode (ACF-Al) was prepared by coating alumina (Al2O3) gel on the surface of activated carbon fiber (ACF) with sol-gel method and heating treatment, and the obtained electrode was characterized with the SEM, XRD and pore size analysis. Subsquently, The artificial wastewater was tested in the lab to evaluate the electroadsorption performance of fluoride removal. Results showed that the modified ACF-Al electrode inhabited twice the capacity than the original ACF electrode on sodium fluoride adsorption. The operating parameters were optimized by response surface test with a result of voltage 2.5V, concentration 15mg/L, and pH 5.72 separately. Moreover, the treatment performance can be further improved by application of two pairs of electrodes, so that the effluent water quality could meet the sanitary standard of drinking water. This novel electrode showed good stability that the adsorption capacity was little reduced after several cycles of regeneration. Finally, the adsorption mechanism was investigated with the simulation of the Langmuir isotherm model, as well as the analysis of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Results showed that the adsorption kinetics followed the pseudo-first-order kinetics model, and this process was accomplished by physical electroadsorption, and ion replaces of -OH group on ACF-Al surface through ion exchange and chemisorption.
2023 Vol. 43 (8): 3974-3982 [Abstract] ( 244 ) [HTML 1KB] [ PDF 1050KB] ( 1759 )
3983 Research progress on separation principle and selective permeability of magnesium and lithium by nanofiltration membrane
WANG Wu-bin, WANG Jin, DOU Meng-meng, ZHANG Qing-yun, WANG Xiao-yue, HUO Kai-li, HAN Chao
This paper reviews recent studies on the separation of magnesium and lithium using nanofiltration membranes, with a primary focus on their physicochemical characteristics, ionic conductivity, and hydration features. It explains the main mechanisms of composite nanofiltration membranes in lithium extraction from salt lakes. Building upon the concept of interfacial polymerization, this review presents recent research on the separation of magnesium and lithium using composite nanofiltration membranes. These membranes are prepared through various methods such as aqueous monomer design, organic monomer design, surface grafting of the polyamide layer, reverse interfacial polymerization, the introduction of intermediate layers, and the modification of support layers. The characteristics of layer-by-layer self-assembly and coating cross-linking in optimizing nanofiltration membrane performance are elucidated. Finally, this paper provides a summary and future outlook for the separation of magnesium and lithium using nanofiltration membranes, from the perspectives of membrane modification methods, practical environmental applications, and industrial development. The aim is to offer theoretical support and practical guidelines for research fields such as lithium extraction through nanofiltration.
2023 Vol. 43 (8): 3983-3993 [Abstract] ( 196 ) [HTML 1KB] [ PDF 1797KB] ( 4614 )
3994 Control of trihalomethanes formation potential by an innovative enhancement filter aid:ferric chloride-chitosan (FC-CTS)
WANG Shan, LIU Jin-hu, HUANG Xin, XU Ying-xin, ZHANG Ke-feng, SHI Bao-you, JIA Rui-bao
Due to the high aromatization degree of dissolved organic matter (DOM) in Yellow River water, its removal by conventional coagulation-filtration process was ineffective. Therefore, this study analyzed the characteristics of DOM in effluent of sedimentation tank and investigated the effects of the ferric chloride (FC), chitosan (CTS) and ferric chloride-chitosan polymers (FC-CTS) micro-flocculation on the enhanced filtration efficiency. The results showed that the molecular weight of DOM in raw water was <1kDa and 3~10kDa, with hydrophobic acidic and hydrophilic neutral organics as the primary components. The 3D-EEM results indicated that the proportion of tryptophane proteins and soluble microorganism metabolites were high. The micro-flocculation filter dose with FC-CTS filter aid exhibited a better performance than FC and CTS. With FC-CTS ratio of 7:2(w.w) and the FC dosage of 0.7mg/L, the turbidity decreased to 0.124NTU, and the DOC removal rate was 31.37%. Meanwhile the hydrophobic and hydrophilic neutral organics in the molecular weight range of <3kDa and >10kDa were significantly eliminated, and the sum of the trihalomethanes formation potential concentration to limit value ratio was 0.744in the sand filter effluent. Under weak alkaline conditions, FC-CTS could be employed to enhance migration and adhesion of colloidal particles and organic matter to the filter media surface through adsorption electrical neutralization of iron hydrate ions and the polymer adsorption bridging of CTS. The proposed process can offer new insights and guide the application of an effective micro-flocculation filter process.
2023 Vol. 43 (8): 3994-4002 [Abstract] ( 176 ) [HTML 1KB] [ PDF 1226KB] ( 1978 )
4003 Constraint of nitrogen behavior on dissolved oxygen deficit in the tidal river
WEN jing, HUANG Bang-jie, HUANG Zhi-wei, FANG Huai-yang, WANG Long-le, ZHANG Ying-min, ZENG Fan-tang, DU Hong-wei
The Dongjiang River basin was selected as the study area to monitor the spatio-temporal variations in dissolved oxygen (DO), nitrogen concentration and multi-isotope in the basin, so as to provide a better understanding for the quantitative contribution of nitrogen turnover processes to DO depletion. The DO concentrations ranged from 2.96mg/L to 11.47mg/L in the Dongjiang River. In the spring and summer, the downstream of the river became the low DO hot spot, where the highest value in the apparent oxygen utilization (AOU) was up to 4.8mg/L, and a high correlation between water temperature and Cl- concentration and AOU was observed. However, the accumulation of different nitrogen species and δ15N fractionation of nitrification mainly occurred in the downstream river network area in the winter and spring. Based on the end-members mixing model and isotope Rayleigh fractionation model, it was found that nitrogen mainly reflected the conservative mixing driven by hydrological process in the summer whereas nitrogen prone to occur nitrification in the downstream in the winter and spring. The degree of nitrification reached 14.4% and 32.3% in the winter and spring, respectively, which also corresponded to about 7.5% and 5.9% of AOU in maximum, respectively. Therefore, there were certain limitations in the contribution of nitrogen behavior to the low DO in tidal river. Especially, the oxygen deficit in the summer might be dominated by other factors. Our results will provide a new insight into the limitations of current environmental management pattern in judging whether DO will satisfy the water quality standard through the concentration of ammonia nitrogen, and will also provide a support for exploring and establishing the DO assessment systems focused on distinguishing different regions and watersheds.
2023 Vol. 43 (8): 4003-4012 [Abstract] ( 255 ) [HTML 1KB] [ PDF 6293KB] ( 1207 )
4013 Effects of influent nitrogen composition on nitrogen removal and N2O emissions in surface flow constructed wetland with micro-polluted water
SUN Wei, LI Yi-ping, ZHU Li-qin, ZHANG Hai-kuo, YAN Chun-min, SHANG He-qin, SONG Cong-qing, LI Da-sheng, WANG Ling, SUN Jia-xin
To investigate the influence of influent nitrogen composition on nitrogen removal and N2O emissions in free water surface constructed wetland with micro-polluted water, four systems were constructed with influent nitrogen compositions of ρ(NH4+-N)/ρ(NO3--N)=0:1(CW-A), ρ(NH4+-N)/ρ(NO3--N)=0.7:1(CW-B), ρ(NH4+-N)/ρ(NO3--N)=4:1(CW-C), and Yanlong Lake surface flow constructed wetland average influent concentration (CW-D), respectively. The characteristics of nitrogen removal and N2O emission were analyzed, and a method to evaluate the synergistic effect of nitrogen removal and N2O emission in constructed wetlands was proposed. The results showed that:The average removal rate of total nitrogen (TN) in CW-C with high influent ammonia nitrogen (NH4+-N) ratio was (68.31±14.56)%, which was significantly higher than that of other treatment treatments (P<0.05). Treatment CW-D with the average influent concentration of Yanlong Lake also showed a better nitrogen removal of (41.06±17.55)% with the extension of operation time. The NH4+-N removal rate of treatment CW-A with high influent nitrate nitrogen (NO3--N) ratio (-110.12%) was significantly lower than that of other treatment treatments, which was possibly be related to plant absorption characteristics. The NO3--N removal rate increased with increasing NO3--N concentration. The NO3--N removal rate of CW-A with high influent NO3--N ratio (87.60%) was significantly higher than that of CW-C with low influent NO3--N ratio (39.96%, P<0.05). The N2O release fluxes for all treatments were (8.73±7.64), (36.68±6.43), (-0.02±7.43) and (15.08±10.77) μg/(m2·h).Treatment CW-C had the lowest N2O release flux, which was the N2O absorption sink. Considering the amount and rate of reduction of nitrogen removal and N2O emission, the synergistic effect of nitrogen removal and N2O reduction is stronger for high influent NH4+-N ratio ρ(NH4+-N)/ρ(NO3--N)=4:1(CW-C).
2023 Vol. 43 (8): 4013-4023 [Abstract] ( 178 ) [HTML 1KB] [ PDF 818KB] ( 1453 )
4024 Removal of ammonium from water by mud cake for groundwater treatment plant:activity formation and application as filter media coating
JIANG Ling-xin, CHENG Ya, HUANG Ting-lin
In order to apply the manganese (Mn) rich mud cake collected from underground water works to remove ammonium (NH4+-N) from water, the process of catalytic oxidation activity formation of mud cake (referred as activation) was optimized. The effectiveness and mechanism of NH4+-N removal by activated mud cake were investigated, and the actual operation effect of its coated filter media was examined. The results showed that the optimal conditions of activation were 1.5mg NH4+ and 0.5mg Mn2+ per gram of mud cake, and the maximum NH4+-N removal rate could reach 0.243mg/(g·h). The activated mud cake has developed a higher catalytic oxidation activity than the active film. The NH4+-N removal process by the activated mud cake followed the first-order power-law kinetic model. The activation energy of NH4+-N was 10.70kJ/mol between 298.15K and 318.15K. In the column experiment, when the influent NH4+-N concentration was 1.5mg/L, the start-up time of groundwater and tap water was 9 and 13d, and the maximum removal efficiency could reach 93.5% and 82.42%, respectively. The SEM, EDS, and XPS analyses revealed that the activation process resulted in the formation of abundant pores on the surface of the mud cake and the deposition of manganese oxide (MnOx). It was speculated that the removal of NH4+-N by activated mud cake was mainly through the autocatalytic oxidation of manganese to form MnOx, and then catalytic oxidation of NH4+-N to form nitrate, and finally removal by desorption. The activated mud cake does not contain pathogenic microorganisms such as E. coli and has no risk of heavy metal precipitation. It is an cost-effective, clean, and environmentally friendly water treatment material.
2023 Vol. 43 (8): 4024-4031 [Abstract] ( 167 ) [HTML 1KB] [ PDF 714KB] ( 1219 )
4032 Study of air flotation for treatment of drilling wastewater
MA Xiao, CHEN Jian-yi, CHI Hao-di, ZHANG Zhong-zhi, ZHANG Zhi-yong
To realize the standard discharge or reinjection of drilling wastewater, the effect of retention time and air bubble diameter on the removal efficiency of chemical oxygen demand (COD) and suspended solids (SS) was investigated by air flotation, and a focused analysis of the fractional efficiency curve. The results showed that the removal efficiency of COD and SS could be stabilized at 90% and 94% respectively with a retention time of 30minutes. The highest removal efficiency of COD and SS was obtained when the particle size distribution of suspended solids and air bubbles coincide. Suspended solids larger than 20 μm could be effectively removed and the fractional efficiency curve appeared fish-hook phenomenon.
2023 Vol. 43 (8): 4032-4037 [Abstract] ( 194 ) [HTML 1KB] [ PDF 712KB] ( 1478 )
4038 Advanced treatment of drilling wastewater by electrocatalytic oxidation with lead dioxide anode
WANG Sheng-han, WU Xin-yi, CHEN Cai, PENG Xu, WANG He-ming

In this study, two typical actual drilling wastewaters (slurry tank supernatant and slurry plate and frame filter effluent) were pre-treated to obtain four types of electrocatalytic influents:slurry tank supernatant diluted sample (water sample 1), slurry tank supernatant flocculation treatment sample (water sample 2), slurry tank supernatant flocculation air flotation treatment sample (water sample 3) and slurry plate and frame filter filtrate diluted sample (water sample 4). The double cathode electrocatalytic system was constructed with titanium-based lead dioxide (Ti/PbO2) as anode, to perform advanced treatment of the above four types of water samples (influent COD range:95.58~131.7mg/L) in order to explore the electrocatalytic removal of drilling wastewaters. The results showed that the organic pollutants in drilling wastewaters could be efficiently and non-selectively removed by electrocatalysis. The highest COD removal efficiency of water sample 3 reached 84.31% after 40 min of treatment. The effluent ammonia nitrogen and total nitrogen concentrations of water samples 2,3 and 4decreased significantly, but the turbidity increased. This may be because the presence of chloride ions improved the removal efficiency of ammonia nitrogen and total nitrogen, and aluminium ions contributed to the formation of hydroxyl complexes.
2023 Vol. 43 (8): 4038-4045 [Abstract] ( 178 ) [HTML 1KB] [ PDF 1857KB] ( 1638 )
Solid Waste
4046 Influence of substrate composition on the production characteristics of extracellular polymers and foaming performance in anaerobic digestion systems
ZHOU Ying-yue, ZHANG Zhi, LI Lei, YANG Ping-jin, WANG Xiao-ming, PENG Xu-ya
To clarify the influence of substrates composition on the production characteristics and foaming performance of extracellular polymer (EPS) in anaerobic digestion system, three types of food waste, namely high-carbohydrate, high-protein and high-fat, were tested in batch experiments. The EPS production characteristics (concentration, composition, structure, functional groups, etc.), and parameters characterizing the foaming properties (viscosity, surface tension and relative hydrophobicity) and potential (foaming tendency, foam stability, foam diameter and liquid film thickness) of various types of EPS and sludge, were examined in different test groups. The correlation between EPS characteristics and sludge characteristics was also analyzed. The test groups with different substrates produced EPS with different properties. Specifically, the more balanced the substrate composition, the more it tended to be used for gas production, while the high carbohydrate and control groups had significantly higher total EPS concentrations than the rest experimental groups due to the excess carbohydrate content. Carbohydrates, proteins and oils influenced EPS morphology and composition by altering intermediate metabolites, affecting enzyme production and proliferation of microorganisms, respectively. In terms of EPS structure, more humic-like substances were produced under high carbohydrate conditions in the high-carbohydrate and control groups. In terms of functional groups, the alkyl group was reduced in the high-carbohydrate group, the high-protein group produced more hydrophilic nitrogenous functional groups, and the carboxylic acid content increased in the high-fat group. In addition, the relative hydrophobicity of EPS was reduced to varying degrees in all three experimental groups compared to the control group. The correlation analysis revealed that the sludge foaming capacity was significantly more correlated with EPS-related parameters than with substrate categories. Sludge foaming tendency (FP) was strongly correlated with loosely bound EPS (P < 0.01, r=0.979) and soluble EPS (P < 0.05, r=0.678). EPS viscosity also had a positive effect on both FP and foam stability (FS) (P < 0.05), and increased EPS surface tension favored the FS (P < 0.05). In terms of the role of substrates on foaming, carbohydrates may be responsible for the production of larger diameter, more stable foams from the sludge by increasing EPS viscosity and hydrophilicity. Proteins use enzymes to reduce the surface tension of EPS, resulting in smaller diameter and less stable foams, and thus alleviated the foaming phenomenon. Fat reduced the loosely bound EPS (P < 0.05, r =-0.649) and its intermediate metabolite LCFA altered the viscosity of tightly bound EPS (P < 0.01, r=0.788), both contributing to increase the FP.
2023 Vol. 43 (8): 4046-4056 [Abstract] ( 194 ) [HTML 1KB] [ PDF 1485KB] ( 1556 )
4057 Reduction of mineral oil in typical sludge treatment and disposal process-Taking the “thermal hydrolysis + advanced anaerobic digestion + plate frame dehydration + land utilization” treatment and disposal system of municipal sludge in Beijing as an example
ZHANG Yu-hui, ZHU Fen-fen, CHEN Qian, ZHAO Bing, WANG Huan, ZHOU Tian-tian, WANG Yi-yu, WANG Jia-wei, FU Xing-min
Mineral oil concentration in sludge samples collected from each units of the sludge "thermal hydrolysis + anaerobic digestion + plate frame dehydration" treatment process in a wastewater treatment plant in Beijing was measured, the mass flow of mineral oil in the sludge treatment process was calculated, and the planting experiment was conducted to detect the absorption and reduction of mineral oil in the soil-plant system. The sludge from this wastewater treatment plant contained high concentration of mineral oil, and the treatment process of "thermal hydrolysis + anaerobic digestion + plate frame dehydration" had poor effect on reducing mineral oil. The concentration of mineral oil in the sludge cake was 4533.8~10385.9mg/kg and the soil-plant system had obvious effect on removing mineral oil from soil with an average reduction of 84.1%. However, mineral oil mainly accumulated in the valuable parts such as ryegrass leaves and sunflower flowers. Therefore, it is necessary to further study the ecological security of mineral oil in the land utilization and disposal process of sludge.
2023 Vol. 43 (8): 4057-4064 [Abstract] ( 165 ) [HTML 1KB] [ PDF 1689KB] ( 1521 )
4065 The effect of microbial agent on the protein degradation of sludge biological drying systems
ZHANG Feng, LI Jun-hua, LI Ning, SU Ming-xue
Microbial agent EM, microbial agent A, and microbial agent A+EM were used to start the experiment of sludge biological drying systems. The influence of different microbial agents on the degradation of organic matters, especially proteins, during the startup of sludge biological drying systems was exploded. The degree of protein degradation was significantly different in the biodrying systems inoculated with different microbial agents. The protein content of EM group, A group and A+EM group decreased by 25.4%, 20.1%, and 34.2%, and the protein degradation of A+EM group was the most rapid. The efficient protein degradation provided abundant nitrogen sources for microorganisms, which promoted the degradation of polysaccharides and fats in A+EM group with the highest of 63.1% and 30.2%. In addition, the organic matters in A+EM group degraded efficiently, and the humification process of sludge pile showed a retarding trend. Compared with the other two groups, the abundance of thermophilic bacteria (³50℃) was related to the increase of temperature in the A+EM group during the thermophilic period. Especially, the abundance of ammonia-oxidizing bacteria and archaea involved in protein degradation were higher than those in the other two groups. Meanwhile, the results of metabolic pathway analysis indicated the combination of the two microbial agents strengthened tricarboxylic acid, glycolysis, and pentose phosphate cycles. The conversion of protein to ammonia nitrogen and the production and utilization of amino acids such as glucose was aslo promoted by microorganisms, which was one of the important reasons for slowing down the humification process.
2023 Vol. 43 (8): 4065-4079 [Abstract] ( 177 ) [HTML 1KB] [ PDF 2383KB] ( 1694 )
4080 Degradation kinetics of LCFAs and effects on anaerobic digestion
XI Yu, LU Bin, CHEN Hao, ZHANG Meng-na, LI Qian
Long chain fatty acids (LCFAs) affect the stability of anaerobic digestion system. The methanogenic properties of 3typical LCFAs (palmitate C16:0, stearate C18:0, oleate C18:1) at different concentrations and their effects on anaerobic digestion were studied. The methanogenic results showed that the complete degradation of oleate was significantly slower (26d), but the specific methanogenic activity (SMA) was higher, which was 1.2 and 2.7 times that of palmitate and stearate. The lag time (t0) and the maximum methane production rate (Rmax) of the oleate group increased linearly with the rising of the concentration. Thus it can be seen that the influence of saturation degree on the degradation kinetics of LCFAs was greater than the carbon chain length. Microbial community analysis showed that the abundance of Clostridium_sensu_stricto and Petrimonas in the oleate group was higher (10.38% and 10.03%). This may be due to the polyhydroxyl LCFAs produced by saturation before β-oxidation, which degrade more slowly. The addition of oleate also enriched Methanosarcina, Methanosobacterium and Methanomassiliicoccus, strengthening the hydrogenotrophic methanogenesis pathway. In addition, the 3LCFAs had inhibitory effects on each stage of anaerobic digestion. The inhibitory degree was the strongest on methanogenesis (16.51%, 40.49%, 63.77%, respectively), and was affected by both the carbon chain length and saturation degree.
2023 Vol. 43 (8): 4080-4088 [Abstract] ( 237 ) [HTML 1KB] [ PDF 1314KB] ( 1262 )
4089 Study on enhanced anaerobic digestion of excess sludge with K2FeO4 and FeCl3 for organic acid production
TIAN Meng-jia, LIU Feng, LI Xiang, MA Jun, WANG Jia-en, ZHAO Wei-dong
The excess sludge was reduced by alkaline potassium ferrate (K2FeO4)-FeCl3 pretreatment combined with anaerobic digestion. Under the goal of efficient recovery of organic acid, the effects of different forms of iron sources and iron concentrations on sludge reduction were discussed, and the optimal iron concentration was found. The results showed that alkaline K2FeO4 played an important role in the destruction of sludge aggregates during pretreatment. Compared with the blank group, Volatile Suspended Solids (VSS) decreased by 26.79%, median diameter (Dx(50)) decreased by 90%, and sludge settling velocity of 30minutes (SV30) decreased by 33%. The sludge settling performance became better and the sludge reduction effect was obvious. FeCl3 only had flocculation during pretreatment process. During anaerobic digestion, the acid production of sludge pretreated with alkaline K2FeO4 was higher than that of blank group, and the increase of iron ions promoted the rapid production of organic acids. When the dosage of K2FeO4 was 20mg Fe/g VSS and FeCl3 was 21mg Fe/g VSS (that is, TFE dosage of 41mg Fe/g VSS), the sludge showed the maximum volatile organic acids (VFAs) accumulation. On the 3th of digestion, the VFAs reached 436.1mg COD/g VSS, which was 4.45times that of the blank group. Under this iron concentration, after 15days of digestion, the removal rate of PO43--P reached 69.8%, which was 2.03 times that of only K2FeO4 pretreatment. In addition, adding appropriate iron could increase acid-producing bacteria (Actinobacteria phylum and Chloroflexi phylum), which will promote acid production, while the iron dosage was higher than 48mg Fe/g VSS, the activity of main acid-producing bacteria in anaerobic environment would be inhibited.
2023 Vol. 43 (8): 4089-4098 [Abstract] ( 156 ) [HTML 1KB] [ PDF 1099KB] ( 1636 )
4099 Simulation study and optimization of parameters for low temperature drying of sludge using waste heat
ZHOU Yin-xi, SHI Wan, LI Xiao-jiao, YUAN Jin, YU Li, JI Wei, PENG Ya
Aspen Plus process simulation software was used to model low-temperature waste heat drying process, focusing on the effects of drying parameters, i.e., sludge moisture content, recycling air flow rate and bypass ratio. Besides, energy consumption for the dying process was analyzed. The results indicated that the low-temperature drying of sludge was significantly influenced by the outlet temperatures of the heater and condenser. The optimal outlet temperature for the heater was 80℃, while the optimal outlet temperature for the condenser was 40℃. When the target moisture content was 30%, the minimum recycling air flow rate was 97598Nm3/h, and the maximum bypass ratio was 0.70. Increasing the recycling air flow rate and reducing the bypass ratio were beneficial for low-temperature sludge drying. The specific moisture extraction rate (SMER) exhibited an increasing-then-decreasing trend with the increase of recycling air flow rate and bypass ratio. When the target moisture content was 30%, the maximum SMER2 could reach to 24.7kg/kWh. Aspen Plus Simulation can be applied to guide the design of low-temperature sludge drying device and the optimization of corresponding parameters, and further provide theoretical supports for promoting large-scale application of low-temperature waste heat drying.
2023 Vol. 43 (8): 4099-4105 [Abstract] ( 157 ) [HTML 1KB] [ PDF 524KB] ( 1448 )
4106 Research progress of processing technology and characteristics of oily sludge
KANG Ding-yu, LIN Hai, NIU Dong-po, TIAN Gang, XU Rui, ZHANG Zhi-yong, LUO Yi-jing, ZHANG Zhong-zhi
Oily sludge is a solid waste produced during the production and processing of petroleum. The effective treatment of oily sludge is one of the key problems to be solved in the petroleum and petrochemical industry. In this review, the origin, type, and characteristics of oily sludge were described. From the aspects of technical principle, treatment effect and research status, the current domestic and international oily sludge treatment technologies are discussed, analyzed and compared in detail. For example, reduction treatment technologies such as concentration and dehydration, resource treatment technologies such as pyrolysis, hot washing, solvent extraction and ultrasonic, and harmless treatment technologies such as incineration, solidification and biodegradation, and so on. According to the characteristics of oily sludge and treatment technology, the selection method of oily sludge treatment technology is proposed. This method takes the characteristics of oily sludge as the selection standard and selects a variety of treatment technologies to achieve the purpose of efficient treatment of oily sludge with resource utilization and harmlessness. The recent development trend and future research direction of oily sludge treatment technology have been prospected. It is expected to provide some reference significance for the relevant research on oily sludge treatment.
2023 Vol. 43 (8): 4106-4120 [Abstract] ( 222 ) [HTML 1KB] [ PDF 555KB] ( 4774 )
Soil Pollution Control
4121 Adsorption characteristics and influencing factors of copper oxide nanoparticles in soil
CHEN Xiao-chen, ZHANG Chun-peng, YUAN Zi-rui, WANG Kai-yu, ZHANG Jian-yu, YANG Chao-ge
The adsorption characteristics of CuO NPs in soil were investigated by static adsorption experiments. The effects of CuO NPs initial concentration, soil with different properties and pH on soil adsorption of CuO NPs were explored, and the interactions between co-existing organic pollutants (phenanthrene) and CuO NPs and the effects of phenanthrene on soil adsorption of CuO NPs were clarified. The results showed that the adsorption of CuO NPs in soil was in accordance with the pseudo-secondary reaction kinetic model. The dissolution and stabilization of CuO NPs by humic acid and organic matter resulted in low adsorption of CuO NPs by soil. The lowest adsorption of CuO NPs by soil occurred at neutral pH. The presence of phenanthrene occupied some adsorption sites and thus reduced the adsorption of CuO NPs by soil, and the equilibrium adsorption of CuO NPs at initial concentrations of 30 and 50mg/L decreased by 37.3% and 24.7%, respectively, but the presence of phenanthrene did not affect the adsorption process of CuO NPs.
2023 Vol. 43 (8): 4121-4126 [Abstract] ( 256 ) [HTML 1KB] [ PDF 849KB] ( 3056 )
4127 Research on the remediation of uranium-contaminated soil by composite electrolyte enhancement and improvement device
ZHOU Shu-ku, YAN Jia-qing, DUAN Yi, TANG hui, FANG Yan-ling, YIN Zhong-quan
Controlled experiment, single factor experiment and orthogonal experiment were used to study the electrokinetic optimization of uranium contaminated soil. The uranium removal efficiency increased to 55.73%, with an average leaching toxic concentration of uranium of only 0.07mol/L. After applying a composite electrolyte of 0.20mol/L tartaric acid and 0.05mol/L ferric chloride to the optimized device, the energy utilization efficiency increased to 306.21. Meanwhile, uranium mainly exists in the form of positively charged uranyl ion (UO22+) and a minor amount of neutral uranium-tartrate complex by using Visual MINTEQ software, therefore, due to the synergy of electromigration and forward electrodialysis, the migration direction of uranium is from anode to cathode. Subsequently, the experimental parameters yielding the best removal efficiency in this study were determined to be 0.15mol/L of tartaric acid, 0.08mol/L of ferric chloride, and 1.5V/cm of voltage gradient via orthogonal experiment. In addition, the modified device has the potential to improve the effect of soil remediation by ameliorating soil conductivity, zeta potential and pH levels. Moreover, when utilizing the composite liquid made up of tartaric acid and ferric chloride as the electrolyte in the modified device for repairing soil contaminated with uranium, the energy utilization and removal efficiency were elevated, and the toxicity associated with uranium leaching was substantially reduced. Therefore, an efficient and sustainable in-situ remediation technology for uranium-contaminated soil is provided.
2023 Vol. 43 (8): 4127-4136 [Abstract] ( 155 ) [HTML 1KB] [ PDF 1324KB] ( 1442 )
4137 Characterization of soil contaminations in brownfield sites in Northeast China
YANG Jin, PENG Chang-sheng, WU Bin, MA Fu-jun, GU Qing-bao
This paper studied the soil pollution characteristics of 483 brownfield sites in Northeast China from 2010 to 2020, analyzed the brownfield sites of enterprises in different industries in terms of soil pollution possibility, distribution characteristics, pollution types and concentrations, and further explored the relationship between the soil pollution characteristics, pollution risks and industry types of brownfield sites in Northeast China. Five industries, including chemical raw materials and chemical manufacturing, pharmaceutical manufacturing, textile and chemical fiber manufacturing, metal smelting and rolling processing industry, petroleum, coal and other fuel processing industry, are high-risk industries contributing to soil pollution in Northeast China based on analysis of the proportion of polluted plots of the same industry type, the total multiple of exceeding the standard of soil pollutants and the pollution area. Among these industries, the complex pollution caused by chemical raw materials and chemical manufacturing are most serious, where the main pollutants are arsenic, lead, polycyclic aromatic hydrocarbons (PAHs), chlorinated hydrocarbons, petroleum hydrocarbons and BTEX. In addition, pharmaceutical manufacturing, textile and chemical fiber manufacturing industry, metal melting/pressing industries often lead to the combined inorganic and organic pollutions, where the main contaminants are arsenic, lead and PAHs. On the contrary, petroleum, coal, and other fuel processing industries frequently cause organic pollutant leaching such as BTEX, PAHs and petroleum hydrocarbons. The industries of mining, transportation equipment manufacturing, handling and warehousing, real estate, general equipment manufacturing, agriculture, fisheries and livestock are identified as low contamination risk industrial types. The pollution of brownfield sites in Northeast China are dominated by complex pollution, with the main contaminations of arsenic, lead, chromium, polycyclic aromatic hydrocarbons, and petroleum hydrocarbons. Our research suggest that the soil pollution risk and pollution characteristics of the brownfield sites are closely related to their historical industry types and regional characteristics.
2023 Vol. 43 (8): 4137-4146 [Abstract] ( 267 ) [HTML 1KB] [ PDF 1113KB] ( 1856 )
4147 Construction of screening model for remediation of heavy metal pollution in construction land
BAI Gui-qi, FU Kai-bin, CHEN Shu, YAO Jun, ZHA Wei, TIAN Li
To solve the problems of low efficiency and cumbersome process of remediating heavy metal contamination in construction land, this article determined the screening indicators for heavy metal pollution remediation technology in construction land, established the screening indexes for remediation technology, selected optimum heavy metal contaminated soil remediation technology based on improved analytic hierarchy process, improved entropy weight method, multiplication integration method, and improved approximate ideal solution sorting method, and constructed a screening model for heavy metal pollution remediation technology in construction land. The screening model was compared with other models and traditional methods using engineering cases, and the usability and reliability of the model are assessed and verified. The verification results show that the application order of remediation of heavy metal contaminated soil in a sorting and smelting residue field in Gejiu, Yunnan is as follows:chemical passivation > soil leaching > electric restoration > engineering physics. The relative closeness of the four alternative remediation technologies in a smelting waste site in Huili, Sichuan Province is P=[0.0519, 0.0502, 0.0830, 0.0870]. The optimized chemical passivation technology and soil solidification technology are in line with the field practice. It is demonstrated that the constructed technical screening model is efficient and accurate, which has significant theoretical value and engineering application value for enhancing the heavy metal pollution remediation technology screening process.
2023 Vol. 43 (8): 4147-4153 [Abstract] ( 184 ) [HTML 1KB] [ PDF 704KB] ( 1474 )
4154 Environmental geochemistry baseline and pollution assessment of soil heavy metals in typical river source area of northeastern Hunan Province
YANG Zhen-yu, LIAO Chao-lin, LI Yi, ZOU Yan, XIE Wu-jin, CHEN Xiao-wei, ZHANG Yu-fei
A total of 87 surface soil samples were collected from typical river source areas in northeast Hunan Province, and the distribution characteristics of soil heavy metals (Cd, Pb, Cr, Hg and As) were analyzed. The environmental geochemical baselines of five heavy metals were determined by the standardized method of reference elements and the cumulative frequency curve method, and the environmental pollution status was evaluated with the environmental geochemical baselines and environmental background values, respectively. The mean values of soil Cd, Pb, Cr, Hg and As were 0.197, 41.065, 130.512, 0.294, 11.633mg/kg, respectively. The environmental geochemical baseline values of soil Cd, Pb, Cr, Hg and As were 0.196, 41.065, 126.301, 0.283, 9.931. The pollution evaluation results based on the environmental geochemical baseline values show that 79.31% of the points in the typical river source area of northeast Hunan have a comprehensive pollution index ranging from 1.0 to 2.0, which is in the mild pollution level, and the pollution indexes of the five heavy metals are all less than 1, which is in the non-pollution level. The environmental geochemical baseline determines the evaluation benchmark for small-scale spatial areas, which can compensate for the pollution caused by the lack of baseline values. The environmental geochemical baseline determines the spatial small-scale regional evaluation benchmark, which can make up for the ambiguity of its assessment results due to the lack of benchmark values.
2023 Vol. 43 (8): 4154-4163 [Abstract] ( 179 ) [HTML 1KB] [ PDF 949KB] ( 1343 )
4164 Review on heavy metal bioavailability and bioaccessibility in soil-crop system
GUO Ke-xin, LI Tian-yuan, SONG Fan-yong, FU Xiao-wen, ZHANG Qiang, JI Lei
Based on the existing research, the morphological methods and biological models commonly used for determining the bioavailability of heavy metals in soils and crops were outlined, and several in vitro methods commonly used for studying the bioaccessibility of heavy metals in soils and crops were summarized, and the factors influencing the bioaccessibility and bioavailability of heavy metals were analyzed, with a focus on the effects of the physical and chemical properties of the media, the interaction between various forms of heavy metals and exogenously added substances on the bioaccessibility and bioavailability of heavy metals in soils, as well as the effects of heavy metal morphology and subcellular distribution of heavy metals on the bioaccessibility and bioavailability of heavy metals in crops. Future research directions on the bioaccessibility and bioavailability of heavy metals in soils and crops were suggested, which may provide theoretical references for future research.
2023 Vol. 43 (8): 4164-4174 [Abstract] ( 190 ) [HTML 1KB] [ PDF 415KB] ( 5492 )
4175 Studies on volatilization of crude oils from three oilfields soils based on GC-MS and gravimetry
SHAN Xiao-ling, LANG Meng-fan, CHEN Hao, ZHANG Shi-long, WANG Tie-cheng, HE Weng-xiang, GUO Xue-tao
Taking crude oils and surrounding soils from Shengli, Nanyang and Yanchang oilfields as research objects, a light-proof volatilization device with controllable temperature was designed to examine the effects of temperature and concentration on the volatilization of oil from polluted soils. a light-proof and ventilated experimental device of volatilization with controllable temperature was built to research the effects of temperature and concentration on oil volatilizing from soils. The results showed that the cumulative volatilization rate of petroleum hydrocarbons was positively correlated with temperature and negatively correlated with oil contents. The crude oil volatilized rapidly in the first three days, followed by gradual volatilization until reaching equilibration at 28days. The equilibrium volatilization percentage of Shengli crude oil was 34%, while above 55% and 70% for Yanchang and Nanyang crude oil, respectively. The volatilization of crude oil from soils fitted well with the first-order reaction kinetic equation (R2>0.968). The relationship between the equilibrium volatilization rate of crude oil from soils and temperature or oil concentration agreed with the Parabola2D surface model (R2>0.972). The composition changes of the three crude oils before and after volatilization were then qualitatively analyzed by GC-MS. The light components in crude oil volatilized continuously, while the varieties of heavy components increased initially and then decreased to a steady state in the end. This study provided a theoretical base for evaluating the environmental behavior of petroleum pollutants in soil and technical support for the remediation of petroleum contaminated soil.
2023 Vol. 43 (8): 4175-4182 [Abstract] ( 154 ) [HTML 1KB] [ PDF 1313KB] ( 1327 )
4183 Effects of root exudates on bioaugmentation of PAHs-contaminated soil
LI Yu-ting, BAO Wen-xiu, ZHANG Wen, WANG Jia-ning, HUANG Yu-jie, SONG Fan-yong
A soil microcosm experiment was conducted to investigate the effect of bioaugmentation on polycyclic aromatic hydrocarbons (PAHs)-contaminated soil and the influence of root exudates on bioaugmentation. The content of PAHs residue was decreased by 15.8% with PAHs-degrading bacteria (Brucella, Ochrobactrum, Sphingomonas, Klebsiella and Acinetobacter sp.) compared to CK in 21d. The addition of ryegrass or artificial root exudates significantly enhanced the bioaugmentation effect and the contents were decreased by 26.3% and 24.6% compared to CK, respectively. These 3bioaugmentation treatments altered the soil bacterial community structures. Compared with the inoculation of PAHs-degrading bacteria alone, the addition of root exudates changed the community structure more significantly and increased the abundance of aromatic compounds degradation-related genes more markedly, indicating that the root exudates affected the bacterial community by promoting the growth of PAHs-degrading bacteria and thus enhanced the bioremediation effect. The different effects of the two types of root exudates on soil bacterial community did not lead to a difference in their contribution to the promotion for bioaugmentation. This study can provide a reference for optimizing bioaugmentation remediation techniques for organic-contaminated soils.
2023 Vol. 43 (8): 4183-4193 [Abstract] ( 178 ) [HTML 1KB] [ PDF 3090KB] ( 1815 )
4194 Comparison of methods for the detection of petroleum hydrocarbon fractions and analysis of degradation kinetics
LIANG Qing-xia, WANG Jia-ning, ZHOU Fang-yuan, HUANG Yu-jie, HUO Qian-wei, CHEN Guan-hong
Gravimetry, ultraviolet spectrophotometry and gas chromatography were used to detect and analyze the components of the original soil contaminated by petroleum hydrocarbons and the soil bioremediated by petroleum hydrocarbon degrading bacteria. By comparison, it is found that gas chromatography has high sensitivity and accuracy, and is more stable as a method to determine petroleum hydrocarbon content in contaminated soil. By combining the utilization of each component of petroleum hydrocarbon pollutants by microorganisms, it showed that this method could effectively reflect the microbial decline. The degradation kinetics of petroleum hydrocarbons in the contaminated soil was studied. The results showed that the degradation rate of petroleum hydrocarbons in the contaminated soil was consistent with the second-order kinetic model. The correlation coefficient of the kinetic equation reached about 0.942, and the half-life of the bactericide was 29d, which was consistent with the degradation trend observed in the experiment.
2023 Vol. 43 (8): 4194-4201 [Abstract] ( 168 ) [HTML 1KB] [ PDF 658KB] ( 1552 )
Environmental Ecology
4202 Characteristics and risk assessment of the bioaerosols emitted from micro-nano bubble aeration process
ZHANG Zhi-qiang, LI Ke-xin, LI Jin, KONG De-ping, HU Xiao-Li-yang, LU Jin-suo
The oxygen dissolving efficiencies, bioaerosol emission characteristics and exposure risk of micro-nano bubble aeration were studied in comparison to the traditional medium/fine bubble aeration. The oxygen mass transfer coefficient (KLa) of micro-nano bubble aeration was up to 1.96 min-1, which was 9.33 and 2.88 times higher than that of traditional medium/small bubble aeration, respectively. Compared to the traditional aeration, the total concentration of bioaerosol emission during micro-nano bubble aeration process decreased by 38.53%, and the spatial dispersion characteristics of bioaerosol were different. The exposure risk assessment results show that the non-carcinogenic risk index (HI) of the bioaerosol produced from micro-nano bubble aeration was less than 1, indicating the non-carcinogenic risk was ignorable. However, the particle size of the bioaerosol ranged in 3~5 level. Therefore, the risk of pathogen transmission caused by inhalation of microbial aerosols by operators during actual production should not be overlooked.
2023 Vol. 43 (8): 4202-4210 [Abstract] ( 235 ) [HTML 1KB] [ PDF 1816KB] ( 1827 )
4211 Greenhouse gases emissions in high polluted water and its restoration
CHEN Cheng, YANG Zheng-jian, WANG Cong-feng, GUO Xiao-juan, TANG Jin-yun
In order to analyze the greenhouse gases emissions in high polluted water, three experimental enclosures were set as:pollution intercepted and ecological restoration treated enclosure (W1), pollution intercepted enclosure (W2) and no treatment enclosure (W3). The CO2, CH4 and N2O diffusion fluxes in W1 were (5671.9±1189.5) μmol/(m2·h), (39.2±10.1) μmol/(m2·h) and (4.2±2.2) μmol/(m2·h), respectively, and contributed for 76.51%, 6.54% and 16.95% of the total CO2 equivalent emission. In the pollution intercepted enclosure W2, the CO2, CH4 and N2O diffusion fluxes were (1139.3±1169.6) μmol/(m2·h), (102.1±35.6) μmol/(m2·h) and (20.0±14.1) μmol/(m2·h), and contributed for 13.64%, 15.12% and 71.24% of the total CO2 equivalent emission. In no treatment enclosure W3, the CO2, CH4 and N2O diffusion fluxes were (9140.3±256.4) μmol/(m2·h), (1126.8±215.1) μmol/(m2·h) and (1.8±1.7) μmol/(m2·h), and contributed for 38.74%, 59.04% and 2.22% of the total CO2 equivalent emission. The total greenhouse gases emission in the experimental enclosures sorted as:no treatment high polluted water > pollution intercepted enclosure > pollution intercepted and ecological restoration treated enclosure. Organic matter degradation in no treatment enclosure W3 resulted in anoxic and high CH4 and CO2 emission. In pollution intercepted enclosure W2, eutrophication and algal bloom occurred. Algae photosynthesis consumed CO2 and released N2O, therefor N2O was the main contributor (71.24%) to the total emission. The high DO in the pollution intercepted and ecological restoration enclosure (W1) inhibited the production of CH4 and accelerated its oxidation, and the inhibition of denitrification resulted in low N2O, which reduced the total greenhouse gases emissions to the atmosphere.
2023 Vol. 43 (8): 4211-4218 [Abstract] ( 210 ) [HTML 1KB] [ PDF 1415KB] ( 749 )
4219 Effects of hydrodynamic conditions on nitrogen and phosphorus release from sediments in shallow lakes
YU Jing-zhi, WANG Xuan, CAI Jian-ying, LIAO Zhen-mei, LI Chun-hui, LIU Qiang
Hydrodynamic conditions are the main natural factors affecting the release of nitrogen and phosphorus from sediments in shallow lakes. It is meaningful to study the effects of hydrodynamic conditions on the release of nitrogen and phosphorus in sediments and to grasp the migration and transformation of water nutrients for preventing lake endogenous pollution in lakes. Among the hydrodynamic factors, the flow velocity can change the exchange flux of nitrogen and phosphorus of the sediment-water interface by affecting the shear stress. Both water level and water disturbance affect the physical and chemical characteristics of surface sediments and the REDOX reaction process of sediment-water interface, and thus jointly affect the release of nitrogen and phosphorus through multiple coupling effects. The mechanism of major hydrodynamic factors such as velocity, water level, water disturbance on nitrogen and phosphorus release in shallow lake sediments was reviewed and the prospect was put forward:The mechanism of coupling effects of various hydrodynamic factors on nitrogen and phosphorus release, the construction of in-situ monitoring and coupling simulation research system based on multi-temporal and spatial scales, and the impact of endogenous nitrogen and phosphorus release on the ecosystem need to be further strengthened.
2023 Vol. 43 (8): 4219-4228 [Abstract] ( 179 ) [HTML 1KB] [ PDF 1009KB] ( 2479 )
4229 Research progress on heavy metal migration model at watershed scale
LIU Lian-hua, ZHANG Qing-wen, WANG Yi-di, GU Xiang
This paper elucidated the main sources, migration mechanisms of heavy metals in the watershed and reviewed the characteristics of commonly used empirical and mechanistic models. The advantages and disadvantages of common-used models were compared synthetically. Results showed that, heavy metal migration models have been improved from the empirical models with simple linear or nonlinear to the mechanism models with the migration and transformation with hydrological and soil erosion processes. The applicability of heavy metal migration models is gradually expanding, and the simulation accuracy is constantly improving, which play an important role in the simulation of heavy metal loadings and water quality prediction. Empirical models require fewer basic data and have relatively simple calculation processes, making them suitable for rough evaluation of heavy metal loadings in the watersheds with limited data. Mechanism models require many high-accuracy data, and have complex model structures, which can achieve the detailed simulation of heavy metal migration processes. The authors proposed outlook on the development of multiple model coupling, the mechanism research of different migration paths, and the identification analysis of heavy metal pollution tracing. Achieving these prospects will provide scientific support for the application, improvement, and source identification of heavy metal pollution at watershed scale.
2023 Vol. 43 (8): 4229-4238 [Abstract] ( 235 ) [HTML 1KB] [ PDF 748KB] ( 2294 )
4239 Phosphorus-facilitated transport of ferrihydrite colloid and retardation effect of ion:Experiment and model calculations
MA Jie, FENG Bing-cong, LIU Yong, CHEN Ya-li, WENG Li-ping, LI Yong-tao
The cotransport of FHC with P and P/Na(Ca) in the saturated sand columns was investigated. The results showed that P adsorbed on the FHC provided a negative charge to the FHC, which enhanced the transport of FHC in the quartz sand columns. The enhanced effect mainly occurred at pH 6.0 and 8.0, while it was hardly discovered at pH 4.0. A high concentration of P (10mg/L) had a stronger ability to enhance the transport of FHC. Both Na+(1 and 10mmol/L) and Ca2+ (0.5mmol/L) could promote the deposition of P-FHC. The retarded effect of Na+ on P-FHC transport was owing to ionic strength, and the retarded effect was relatively weak. However, Ca2+ retarded FHC transport in multiple ways, including ionic strength, increase in the heterogeneity of charge distribution in the colloidal system, and heteroaggregation between generated precipitate and FHC at high pH. Therefore, retarded effect of Ca on P-FHC transport was strong. The results provided support for further investigation of the environmental behavior of anion-facilitated transport of colloid and nanoparticle.
2023 Vol. 43 (8): 4239-4246 [Abstract] ( 140 ) [HTML 1KB] [ PDF 1090KB] ( 1737 )
4247 Degradation of biodegradable plastic PBAT/PLA under typical non-biodegradable environment
ZHENG Han-yue, SUN Jiao-xia, XIANG Hong, ZHOU Yao, JIANG Hui, FAN Jian-xin
The biodegradable plastic poly (butylene adipate-co-terephthalate/poly(lactic acid) (PBAT/PLA) and the traditional plastic polyethylene (PE) were degraded for 9months under two typical non-biological degradation conditions, ultraviolet light (UV) and mechanical abrasion (MA). The physical and chemical properties of two kinds of plastics were analyzed by scanning electron microscope-energy spectrometer (SEM-EDS), static water contact angle, water uptake ratios and weight loss. And the quality and proportion of degradation products with different particle size were characterized by total organic carbon (TOC) assay. The results showed that PBAT/PLA exhibited greater changes in surface morphology, oxygen carbon ratio, water absorption and mass loss than PE under both UV and MA conditions. Especially under UV conditions, the quality loss rates in March, June and September reached 3.5%, 6.2% and 17.9%, respectively. Degradation product analysis showed that the quality of degradation products of PBAT/PLA were much higher than those of PE. And PE mainly produced microplastics (MPs) larger than 0.22μm, while PBAT/PLA mainly produced degradation products smaller than 0.22μm under the UV condition. In March, June and September, the proportion of mass was 83.8%, 87.2% and 79.4%, respectively. Some of the degradation products may eventually degrade to produce volatile substances. Similar to PE, PBAT/PLA produced more MPs larger than 0.22μm under the MA condition. In March, June and September, the proportion of mass was 100%、91.2%和81.7%, respectively.
2023 Vol. 43 (8): 4247-4254 [Abstract] ( 146 ) [HTML 1KB] [ PDF 2377KB] ( 2651 )
4255 Mechanisms on algal bloom control in canyon stratified reservoir by water lifting and aeration
KONG Chang-hao, HUANG Ting-lin, WEN Cheng-cheng, ZHANG Chun-xiao, LIU Yu-xuan, CHENG Ya, ZHAO Tong
To explore the effects of water lifting and aeration (WLAs) on the algal biomass and structure in different radial directions in canyon stratified reservoir, the Lijiahe Reservior (LJHR) was select to obtain the succession pattern and control mechanism of algae based on the high-frequency monitoring of water physicochemical parameters and the number and species of algae during the water lifting and aerators (WLAs) operation. These results showed that the reduction rates of algal cell density in the sites from S1to S4were 92.7%, 92.9%, 92.1% and 89.2%, respectively, after 12 days of the WLAs operation. The algal structure in the sites from S1to S4was changed, with the shift from Chlorophyta (Scenedesmus) and Bacillariophyta (Eunotia and Pinnularia) to Bacillariophyta (Synedra and Cyclotella) (i.e., high-temperature, large, and low surface to volume (S/V) algae" to "low-temperature, small, and high S/V ones). The reduction of water temperature, light availability (Zeu/Zmix), nutrients, and an increase in mixing depth (Zmix) were the main drivers for the algal control by WLAs. The increase of phytoplankton assemblage (Q) index and decrease of the trophic level index (TLI) in the sites from S1 to S4, indicated the eutrophic improvement.
2023 Vol. 43 (8): 4255-4266 [Abstract] ( 144 ) [HTML 1KB] [ PDF 4548KB] ( 1376 )
4267 Global distribution of synthetic musks in organisms and human bodies
LI Dan-yang, WU Ying-xin, WANG Tao, ZOU Hong-yan
The distribution patterns of various synthetic musks in humans and organisms around the world are summarized and the associated bioaccumulation and toxicity are discussed. Galaxolide (HHCB), tonalide (AHTN), musk xylene (MX) and musk ketone (MK) often have the highest detection frequencies in all organisms (HHCB:20~100%; AHTN:7~100%; MX:6~95%; MK:3~98%) while other synthetic musks such as cashmeran (DPMI), celestolide (ADBI), phantolide (AHMI), traseolide (ATII), musk moskene (MM), musk tibetene (MT) and musk ambrette (MA) have lower detection frequencies and concentrations. Being the most representative synthetic musks in humans and other organisms, the levels of HHCB and AHTN were consistent with their use patterns. The lipid-weight based bioaccumulation factor (BAFL) varied greatly among different species in different regions, caused by different metabolisms and tissue sampled. Meanwhile, synthetic musks could impose inhibitory effects on the growth and development of organisms, have acute toxicity in the early life of fish and produce synergic toxicity in the presence of multiple contaminants. Future studies might focus on the evaluation of long-term toxicity and combined exposures to these low-concentration synthetic musks on organisms. More attention should be also taken on the toxicity of metabolites. Furthermore, it is necessary to develop the relevant environmental criteria or ecological risk thresholds.
2023 Vol. 43 (8): 4267-4279 [Abstract] ( 319 ) [HTML 1KB] [ PDF 569KB] ( 2338 )
4280 Effect of spatial scale on water quality in watershed land use analysis
YI Fan, CHEN Min, HE Xiao-feng, YU Ching-hao, AN Rui-dong
The Dadu River Basin was chosen as the research area to explore the interrelationship between land use and water quality at different spatial scales. Based on the data on river water quality and land use in 2020, the basin was divided into upstream, middle and lower reaches. At six different spatial scales (100 m buffer zone, 200 m buffer zone, 500m buffer zone, 1000m buffer zone, 2000 m buffer zone, and catchment), the land use was then extracted, considering the significant landform variations in the Dadu River Basin. Various correlation analysis methods, including redundancy analysis, principal component analysis, and the Spearman correlation coefficient method, were employed to quantitatively explore the impact of land use on river water quality. The foundation for managing land use structures and ensuring the security of water resources is laid by this study. It is shown by the results that:The evaluation results of the watershed water quality based on the WQI index are all in good or higher grades, and the water quality of the middle and lower reaches of the basin is better than that of the upstream. In the upstream region of the river, a positive correlation is observed between dissolved oxygen (DO) and pH, as well as between the permanganate index (CODMn), ammonia-nitrogen (NH3-N), and total phosphorus (TP) within the buffer zone with the woodland. In the middle and downstream sections of the river, significant negative correlations are found between pH and DO with the grassland, which has a smaller area. Additionally, a weak negative correlation with TP is observed for the construction land. In conclusion, the correlation between water quality and land use types is stronger in the upstream and downstream buffer zones of the basin compared to the catchment area. Moreover, it is shown that the correlation between water quality and land use patterns is more significant in the large spatial scale buffer zone (2000 m). Therefore, for the protection of water quality within a 2000 m range on both sides of the river banks, measures should be taken to strengthen the prevention of adverse effects caused by construction land on water quality in the upstream area. Additionally, closer attention should be paid to the pollution caused by cultivated land in the middle and lower reaches.
2023 Vol. 43 (8): 4280-4291 [Abstract] ( 204 ) [HTML 1KB] [ PDF 2763KB] ( 1730 )
4292 Dynamic variation of vegetation EVI and its driving mechanism in the Sichuan Basin
DAI Qiang-yu, XU Yong, ZHAO Chun, LU Yun-gui, HUANG Wen-ting
This study took the Sichuan Basin as the study area. MOD13A3EVI time series, climate data, land use type data, and nighttime light data were obtained, and Thile-Sen Median analysis, correlation analysis, multi-collinearity test, residual analysis, and relative analysis were utilized to explore the spatial-temporal variation of vegetation EVI and the driving mechanism of vegetation EVI in the Sichuan Basin from 2000 to 2020. Results showed that the vegetation EVI in 83.81% of the Sichuan Basin showed an upward trend from 2000 to 2020, which were concentrated in the central and eastern of the Sichuan Basin. Accounting for 16.19% of the vegetation EVI in the Sichuan Basin exhibited downward trends, which were mainly located in the Chengdu and Chongqing metropolitan areas and sparsely distributed in other regions. At the city scale, except for a downward trend of vegetation EVI observed in Chengdu, the vegetation EVI of all cities in the Sichuan Basin showed an upward trend. Vegetation EVI variation in the Sichuan Basin was dual-regulated by climate change and the effects of climate change to vegetation EVI showed obvious regional differences. At the regional scale, vegetation EVI was positively correlated with minimum temperature and precipitation, but negatively correlated with atmosphere pressure in the Sichuan Basin. In addition, vegetation EVI had the highest correlation with precipitation. The area where minimum temperature and precipitation promoted vegetation growth in the Sichuan Basin was greater than that with inhibitory effect, while the area where air pressure had an inhibitory effect on vegetation growth in the Sichuan Basin was greater than the area with promoting effect. The combined impact of precipitation, minimum temperature, and atmosphere pressure on vegetation EVI variation was greater that other climatical-driving types. Human activities exhibited dual effect on vegetation EVI variation, and the positive effect was greater than the negative effect. Urban expansion and population increase leading to the increase of construction land and the massive transfer of forest land to cultivated land, respectively, had degraded the vegetation EVI. Meanwhile, the development of agriculture and forestry and implementation of ecological engineering leading to the increase of forest land and the massive transfer of grassland to cultivated land, respectively, had improved the vegetation EVI.Vegetation EVI increase was mainly driven by the combined effect of climate change and human activities. Furthermore, the impact of climate change on vegetation EVI increase was greater than that of human activities, and the impact of human activities on vegetation EVI decrease was greater than that of climate change. The research result can provide a theoretical reference for dynamic vegetation monitoring and eco-environmental quality assessment in the Sichuan Basin.
2023 Vol. 43 (8): 4292-4304 [Abstract] ( 195 ) [HTML 1KB] [ PDF 5000KB] ( 1209 )
4305 Research on the application of petroleum hydrocarbon degradation genes and their recombinant bacteria
CHANG Xiao-yu, JI Lei, HUANG Yu-jie, SONG Fan-yong, WANG Jia-ning
Petroleum hydrocarbon pollution is currently a serious environmental problem. Microbial remediation is an effective means of remediating petroleum hydrocarbon contamination at this stage. Microorganisms are able to degrade petroleum hydrocarbon pollutants through a series of enzymes encoded by degradation genes. Therefore, the study of petroleum hydrocarbon degradation genes can not only clarify the degradation mechanism but also provide a theoretical basis for the construction of petroleum hydrocarbon degradation genetic engineering bacteria. This paper summarized the functional genes and key enzyme species for petroleum hydrocarbon degradation, focused on the metabolic pathways of long-chain alkanes and their degradation genes. The current strategies for the construction of petroleum hydrocarbon degrading genetically engineered bacteria are summarized, the problems and shortcomings of the existing studies are outlined, and the future prospects for the use of genetic engineering technology to improve the remediation efficiency of petroleum pollution are presented.
2023 Vol. 43 (8): 4305-4315 [Abstract] ( 274 ) [HTML 1KB] [ PDF 468KB] ( 2396 )
4316 Research progress on stability and demulsification mechanism of crude oil emulsions
FENG Cheng, ZHENG Huan-ling, WANG Jia-ning, SONG Fan-yong, LI Tian-yuan, FU Xiao-wen, HUANG Yu-jie, ZHANG Wen
Crude oil emulsion is a complex oil-water system produced in the process of crude oil exploitation. The natural interfacial active substances and added polymers increase the stability of the emulsion. Gum and asphaltene are considered as the main stabilizers of the oil-water emulsion. Chemical demulsification is a method to separate oil from water by adding demulsifier to emulsion, but the mechanism of demulsification has not been confirmed. The influence mechanism of interfacial active substances in crude oil emulsions, including interfacial film, interfacial tension, gel, asphaltene and so on, on the stability of emulsions was reviewed. The development status and trend of demulsifiers and their effects on emulsions were discussed. At present, the main research directions of demulsifiers include modification and combination, research and development of polyquaternary ammonium salt, polyethers and other demulsifiers The research status of demulsification mechanism and the future research direction of demulsification mechanism and demulsifier were prospected.
2023 Vol. 43 (8): 4316-4325 [Abstract] ( 407 ) [HTML 1KB] [ PDF 553KB] ( 2437 )
Emerging Contaminants and Environmental Toxicology
4326 Study of the molecular mechanism of low-dose PFOS exposure-induced testicular steroidogenesis disturbance
CHEN Hai-bin, HUA Wei-zhen, HUANG Qing-yu
Proteomic technique was employed to analyze the differential expression profile of rat testicular proteome after exposure to 0.015, 0.15 and 1.5mg/kg of PFOS for two months. The results showed that the progesterone and testosterone levels in rat serum were significantly increased, and the expressions of 56 proteins in testis tissue were significantly altered after PFOS exposure. Among them, 10 differentially expressed proteins (DEPs) were closely related to fatty acid metabolism and testicular steroidogenesis (9proteins were up-regulated and 1was down-regulated). In addition, most fatty acid metabolism-related DEPs were statistically and biologically correlated with steroidogenesis-related DEPs. These results indicate that low-dose PFOS can accelerate fatty acid metabolism and steroidogenic process in rat testis, ultimately stimulating the synthesis of steroid hormones, progesterone and testosterone. This study can provide new clues to the toxicological mechanism of testicular steroidogenesis disturbance induced by low-dose PFOS exposure, and implicate the male reproductive health risk of humans environmentally exposed to PFOS.
2023 Vol. 43 (8): 4326-4333 [Abstract] ( 145 ) [HTML 1KB] [ PDF 613KB] ( 1658 )
4334 Interactive effects of polystyrene microplastics and bisphenol A on bioaccumulation and oxidative stress in the Yellow River carp (Cyprinus carpio haematopterus)
HOU Chen-li, YU Yue, YU Ling-hong, WANG Zhi-chao, YU Sheng-qian, LI Wei-ping
The purpose of the present study was to elucidate the effects of MPs (microporous) on the distribution and bioaccumulation of BPA (bisphenol A) in fish as well as their interactive toxicological effects in fish. Yellow River carp (Cyprinus carpio haematopterus) was employed as the model organism. In this study, the tissues accumulation characteristics of PS-MPs and BPA, histopathology and antioxidant enzyme activities of Yellow River carp under the combined with (0.5µm) PS-MPs and BPA were analyzed. The enrichment of PS-MPs followed the order of gut (55.70%) >gill (31.53%)> brain (7.76%) >liver (5.01%) in various tissues of carp after 21days of exposure. Compared with BPA treatment, BPA concentrations of BPA+MP20treatment in gill, liver, gut and brain were increased by 4.28%, 1.66%, 2.06% and 4.85%, respectively, increased by 11.88%, 15.18%, 3.15% and 10.54% in BPA+MP100 treatments, respectively. The presence of PS-MPs significantly increased the accumulation of BPA in carp tissues, and the accumulation of BPA in tissues increased with the increase of the concentration of PS-MPs, and the accumulation of BPA in liver was more dependent on the concentration of PS-MPs. Compared with the control treatment, single BPA or MPs combined with BPA could cause different degrees of inflammatory cell infiltration in each tissue of carp, and induce the increase of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) activity and malondialdehyde (MAD) content in each tissue. However, interactive effects of BPA and high concentration of PS-MPs, the SOD and GSH activities in the intestine and liver of carp were induced to decrease the content of MAD, to mitigate the combined toxic effects of microplastics and bisphenol A on carp.
2023 Vol. 43 (8): 4334-4342 [Abstract] ( 185 ) [HTML 1KB] [ PDF 1903KB] ( 1769 )
4343 Toxic effects of polylactic acid microplastics to Daphnia magna
LIU JIA-qiang, JIANG Yuan-yuan, YANG Yang-yang, CHENG Hai, XU Lei, LIU Qiang, FAN Xiu-lei
In order to further reveal the effects of biodegradable microplastics on aquatic organisms, the acute and chronic toxic effects of polylactic acid (PLA) microplastics on Daphnia magna were studied using Daphnia magna as the model organism. The results showed that the half effect concentration (48h-EC50) of PLA on Daphnia Magna was 59.43mg/L, with a 95% confidence interval of 53.55~65.97mg/L. Additionally, the toxicity of PLA was reduced by ultraviolet irradiation treatment. PLA inhibited the swimming activity and feeding behavior of Daphnia magna in a concentration-dependent manner. Compared with the control group, PLA at 100mg/L significantly inhibited the heart rate and thoracic limb activity of Daphnia magna, with maximum inhibition rates of 31.4% and 17.7%, respectively. After long-term exposure for 21days, both 10 and 40mg/L PLA inhibited the reproduction and intrinsic rate of population growth (rm) of Daphnia magna to some extent, but the effects were not significant. Exposure to PLA at 40mg/L significantly reduced the survival rate of Daphnia magna (only 20%). PLA exposure significantly induced superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, indicating that Daphnia magna was subjected to oxidative stress and caused lipid peroxidation damage. At the concentration of 40mg/L, PLA significantly inhibited the acetylcholinesterase (AChE) activity, resulting in neurotoxicity and motor disorders of Daphnia magna
2023 Vol. 43 (8): 4343-4352 [Abstract] ( 203 ) [HTML 1KB] [ PDF 1181KB] ( 2179 )
4353 Oxidative stress responseresponse of petroleum-contaminated soil to earthworm
OUYANG Shao-hu, HUANG Pan-pan, TAO Zong-xin, ZHOU Qi-xing
The ecological toxicity of petroleum-contaminated soil of the Yellow River Delta on the earthworm (Eisenia foetida, test organisms) were investigated under 28d toxicity exposure, and then the ecotoxicity threshold of petroleum hydrocarbon in soil environment was preliminarily deduced, which could provide support for soil ecotoxicology diagnosis. The results showed that the activities of antioxidant enzymes and content of MDA in Eisenia foetida had no obvious response to exposure time after exposure to different concentrations (0~10g/kg) petroleum hydrocarbon contaminated soil for 7d, 14d, 21d and 28d. In response to the exposure concentration, the activities of SOD, CAT and POD in earthworms didn't have a uniform trend and couldn't be generalized. However, there was a positive linear correlation between the content of MDA in earthworms and the exposure concentration of petroleum hydrocarbons (R2>0.85). Therefore, MDA content of earthworm could be used as a biomarker to indicate lipid peroxidation under petroleum hydrocarbon contaminated soil stress.
2023 Vol. 43 (8): 4353-4359 [Abstract] ( 190 ) [HTML 1KB] [ PDF 432KB] ( 1707 )
4360 Accumulation and sources assessment of heavy metals of Coilia nasus in the Three Gorges Reservoir area
CHEN Qian, XIE Qing, LI You-yi, LÜ Hong-jian, LI Jia-jia, WANG Yong-min, WANG Ding-yong
This study investigated the accumulation characteristics of 10heavy metals (Cr, Mn, Ni, Cu, Zn, As, Se, Ag, Cd, and Pb) in the muscle of Coilia nasus collected from four primary tributaries (Meixi River, Caotang River, Daning River, and Pengxi River) in the Three Gorges Reservoir, and identified the sources of heavy metals and assessed the associated health risks. The average concentrations of Cr, Cu, Zn, As, Se, Cd, and Pb in the muscle tissue of C. nasus specimens from the Three Gorges Reservoir area were found to be below the corresponding standard limits of 2.00, 50.00, 50.00, 1.00, 1.00, 0.10, and 0.50mg/kg. However, compared to other carnivorous fish at similar trophic levels within the reservoir, C. nasus exhibited a notable capacity for accumulating heavy metals. Significant spatial differences were observed in the levels of certain heavy metals in fish from different tributaries. Furthermore, the accumulation of heavy metals was found to be influenced by growth conditions, with varying effects depending on the specific heavy metal. Principal component analysis revealed that combustion of fossil fuels, metal smelting, and industrial wastewater discharge were the major sources of heavy metals in the C. nasus. Specifically, fish specimens from the Meixi River were primarily affected by Zn, Cu, and As, whereas those from the Caotang River were predominantly influenced by Cr and Ni. Health risk assessment results indicate that the single (THQ) and compound (TTHQ) heavy metal risk coefficients were less than 1, suggesting that current consumption of C. nasus in the Three Gorges Reservoir is unlikely to pose a risk to human health. However, it is noteworthy that As accounted for 77% of the TTHQ, thereby indicating a relatively high contribution to the overall health risk. Overall, this study provides fundamental data for understanding the presence of heavy metals within the food web of the Yangtze River and their potential implications.
2023 Vol. 43 (8): 4360-4369 [Abstract] ( 194 ) [HTML 1KB] [ PDF 865KB] ( 1260 )
4370 Health effects and economic losses of formaldehyde pollution in interior decoration
ZENG Xian-gang, LI Kang-wei, WANG Qi
Based on the mass conservation law of indoor formaldehyde concentration, a dynamic mass balance model of formaldehyde concentration including indoor temperature, humidity and air change times was constructed. The risk of carcinogenesis caused by formaldehyde pollution was evaluated using the health risk assessment model of the United States Environmental Protection Agency (EPA). On the basis of estimating the proportion of decoration, the number of carcinogens caused by formaldehyde pollution from indoor decoration in China and the economic loss were calculated, Monte Carlo simulation was used to analyze the uncertainty and sensitivity. The results show that:① The average formaldehyde concentration after indoor decoration in 2020 was 146.89μg/m3, the average carcinogenic risk of formaldehyde exposure was 9.07×10-4, the two showed the spatial distribution characteristics of "high in the north and low in the south", in which the north exhibited the seasonal distribution characteristics of "high in winter and low in spring", and the south exhibited the seasonal distribution characteristics of "high in summer and low in winter". The formaldehyde concentration and carcinogenic risk were highest in western Xinjiang and western Inner Mongolia after decoration. ② In 2020, the proportion of housing decoration nationwide was 14.4%, which led to 2548people being carcinogenic due to formaldehyde pollution, accounting for 0.06% of the new cancer population in China. The number of people being carcinogenic due to formaldehyde pollution in the south was higher than that in the north. The number of people being carcinogenic due to formaldehyde exposure in Beijing-Tianjin-Hebei Urban agglomeration and the Yangtze River Delta were higher than that in other cities. ③In 2020, DALY reaching 21656person years and economic loss reaching 25.888billion yuan, which accounted for 0.026% of the national GDP, were directly caused by formaldehyde pollution of indoor decoration in China. ④ The consistency between the average value and point estimation of formaldehyde concentration and carcinogenic risk in China's interior decoration was demonstrated by Monte Carlo simulation, and a relative error of approximately 5% was observed. It was demonstrated by sensitivity analysis that the health risk of formaldehyde exposure was most significantly impacted by exposure time, air exchange rate, and formaldehyde rate.
2023 Vol. 43 (8): 4370-4381 [Abstract] ( 255 ) [HTML 0KB] [ PDF 1193KB] ( 2034 )
Carbon Emission Control
4382 Driving factors and attribution analysis of carbon emission intensity change in Beijing-Tianjin-Hebei region
CHEN Liang, ZHANG Nan, WANG Yi-fan, HU Wen-tao
Based on the LMDI-Attribution model, the paper investigated the spatial and temporal evolution of energy intensity, industrial structure and emission factors in Beijing-Tianjin-Hebei region along the Five-Year Plans of China from 2000 to 2020, and retrospectively quantified phased contributions of sub-sectors in each driving factors. Beijing has reached the carbon peak, while Tianjin and Hebei have entered a plateau since 2012. The carbon emission of Hebei province dominated the overall carbon emission trend of Beijing-Tianjin-Hebei region and rebounded during the middle and late stage of 13th Five-Year Plan. The overall carbon emission intensity of Beijing-Tianjin-Hebei region began to turn from rising to falling during the 11th Five-Year Plan, and rebounded in the middle and late 13th Five-Year Plan. From 2000 to 2020, the overall carbon emission intensity of Beijing-Tianjin-Hebei region decreased by 71.09%, among which emission factors contributed the least while energy intensity the most, with a cumulative inhibition contribution rate of 54.36% and an industrial structure of 38.17%. As for the carbon emission intensity change in Beijing-Tianjin-Hebei region, the dominant factor changed from energy intensity during 10th~12th Five-Year Plan periods to industrial structure in the 13th Five-Year Plan; during each period, the two factors, energy intensity and industrial structure, exerted an influence on the carbon emission intensity change basically through industry and transportation. During the four periods, the impact of industry through energy intensity on the change of overall carbon emission intensity presented a V-shaped change, from promoting to inhibiting to promoting again. At the end of the 13th Five-Year Plan, the promoting effect was 7.48%, while the impact through industrial structure showed a continuous and stable inhibiting effect. Since the 11th Five-Year Plan, transportation has continuously suppressed the overall carbon emission intensity change, both through energy intensity and industrial structure. Under the background of carbon peaking and carbon neutrality goals, policy recommendations are provided for the collaborative governance of Beijing-Tianjin-Hebei region.
2023 Vol. 43 (8): 4382-4394 [Abstract] ( 244 ) [HTML 0KB] [ PDF 1147KB] ( 2925 )
4395 The impact of economic growth target on carbon emission efficiency in resource-based cities
BIAN Zhi-qiang, ZHONG Shun-chang
Improving carbon emission efficiency is the key to achieve a win-win situation between economic growth and carbon emissions reduction. Based on the panel data of 114 resource-based cities from 2006 to 2020 in China, this paper estimated the carbon emission efficiencies using the super-efficiency SBM with unexpected output model, and then examined the influential effect, internal mechanism and heterogeneous characteristics of economic growth goals on carbon emission efficiency. The results indicated that:As a whole the carbon emission efficiency of resource-based cities showed a fluctuating upward trend during the study period, but there was significant heterogeneity between cities in different regions and different growth stages. The improvement of the economic growth target significantly reduced the carbon emission efficiency, and this conclusion passed a series of robustness tests such as overcoming the endogeneity. The internal mechanisms were inhibiting technological innovation and strengthening resource dependence. Any degree of addition in economic growth target would inhibit the carbon emission efficiency. The reduction effect of economic growth goals on carbon emission efficiency existed only in the central, western, mature and declining resource-based cities, as well as in the samples before 2013 or 2015. Meanwhile, the negative impact became more apparent as the overcompletion level increased.
2023 Vol. 43 (8): 4395-4408 [Abstract] ( 255 ) [HTML 0KB] [ PDF 574KB] ( 1623 )
4409 Seasonal and spatial variability of greenhouse gas concentration and emission flux in the urban river
LIU Gai-guo, ZENG Yong, YAN Tie-zhu
The concentration and water-air interface emission flux of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were investigated in both winter and summer seasons in the Beiyun River using headspace gas chromatography and model method. And physicochemical indicators of the river were also monitored. The results show that the concentration ranges of CO2, CH4, and N2O in the river were 2.31 to 189.69, 0.05 to 6.11, and 0.02 to 0.28μmol/L, respectively, while the flux ranges were 27.60 to 548.02, 1.10 to 12.43, and 0.181 to 0.500mg/(m2·d). The concentration and flux of CH4 and N2O were higher in the urban river compared to non-urban rivers. The CO2 and CH4 concentration and flux in the Beiyun River showed spatio-temporal heterogeneity. The highest concentration and flux were found in the mixed area II, with higher concentration and flux observed in summer compared to winter. In winter, higher N2O concentration and flux were found in agricultural area, while N2O's seasonal variation remained insignificant. Additionally, the CO2 concentration and flux of the river showed a significantly positive correlation with water temperature and ammonium nitrogen (NH4-N), and a negative relationship with dissolved oxygen (DO) and pH. CH4 concentration and flux had a negative correlation with DO and nitrate (NO3-N), but a positive correlation with water temperature and NH4-N. Salinity, total dissolved solids (TDS), electrical conductivity, and total phosphorus (TP) were the primary factors affecting N2O concentration and flux in the river.
2023 Vol. 43 (8): 4409-4417 [Abstract] ( 292 ) [HTML 0KB] [ PDF 915KB] ( 1931 )
4418 Characteristics of actual road NOx and CO2 emissions from diesel vehicles in Beijing based on remote monitoring
FENG Qian, LIU Bao-xian, YANG Yan-yan, ZHANG Shao-jun, SHEN Xiu-e, LU Yang, WANG Peng-rui, WU Ye
The study adopted remote online monitoring technology to monitor the actual road operating parameters of typical diesel vehicles in Beijing, and conducted synchronous comparative tests with standard PEMS testing equipment to analyze the data consistency of remote online monitoring technology. A micro-operating mode division method applicable to Beijing's diesel vehicles was established based on the analysis, and the NOx and CO2 emission characteristics of typical diesel vehicles were analyzed based on micro-operating mode. The study results show that:1) the NOx and CO2 emissions rates of diesel vehicles monitored by remote online monitoring and PEMS testing data are both linearly fitted with R2 higher than 0.99; 2) the micro-operating mode division of Beijing's diesel vehicles based on the established method conform to normal distribution, achieving the objective of uniformly dividing the vehicle's micro-operating conditions; 3) in different vehicle speed ranges, the NOx and CO2 emission factors of different types of vehicles show different trends, and the NOx emission factor of vehicles with China VI emission standard is generally lower than that of vehicles with China V emission standard. The highest NOx comprehensive emission factor belongs to China V heavy diesel vehicles, (7.63±0.57)g/km; as the tonnage increases, the CO2 emission factor of diesel vehicles will increase to varying degrees and the CO2 emission factor of China VI heavy diesel vehicles is relatively high, possibly due to the relatively complex after-treatment system of China VI vehicles increasing fuel consumption.
2023 Vol. 43 (8): 4418-4426 [Abstract] ( 274 ) [HTML 0KB] [ PDF 681KB] ( 1621 )
4427 Adsorption performance of CO2 on lignin impregnated biochar activated by microwave irradiation
ZHANG Xue-yang, XU Hao-liang, DAI Huan-tao, YOU Xin-xiu, WEI Zhao-long, CAO Ling-yu
Calcium lignosulphonate was selected as precursor to impregnate the biochar and followed by the microwave irradiation to activate the impregnated biochar. The obtained impregnated biochar was characterized by surface area analyzer, SEM, FTIR and Raman, and then its CO2 adsorption ability was investigated. The results showed that both specific surface area and micropore volume of impregnated biochar increased with the decrease of impregnation ratio and then decreased. That was because too much lignin impregnation would block the original pores of biochar, while appropriate small amount of lignin impregnation would modulate and improve the micropore structure of biochar by entering its large size pores. The adsorption capacity of CO2 on impregnated biochar could reach 123.11mg/g, and correlation analysis demonstrated that it was influenced by both specific surface area and micropore volume. Kinetic study showed that the Avrami model fitted CO2 adsorption on biochar more accurately, indicating this adsorption process was dominated by physical adsorption and chemical adsorption. Adsorption isotherm fitting showed that Langmuir model fitted the CO2 adsorption well for the biochar with less lignin impregnation, while Freundlich model fitted the biochar with more lignin impregnation better. This indicated that appropriate small amount of lignin impregnation facilitated the formation of more uniform micropore adsorption sites on biochar. Reusability experiment showed that the adsorption capacity of impregnated biochar remained 98.22%~98.98% after 10 consecutive adsorptions-desorption cycles, indicating that it had excellent reusability. In a word, lignin impregnated biochar assisted with microwave irradiation could be a potential CO2 adsorbent.
2023 Vol. 43 (8): 4427-4436 [Abstract] ( 194 ) [HTML 0KB] [ PDF 1696KB] ( 1929 )
4437 Effects and mechanisms of the digital economy for carbon emission reduction
WANG Wei-guo, WANG Yong-ling, FAN Dan
In this paper, the digital economy of 274 prefecture-level and above cities in China from 2011 to 2019 was measured, and the effect of the digital economy on carbon emission reduction and the mechanisms were explored from both theoretical and empirical dimensions. The results showed that the digital economy significantly reduced carbon emissions. Specifically, for every 1% growth of the digital economy, the total and intensity of carbon emissions decreased by 0.491% and 0.966%, respectively. The positive effect of the digital economy became more and more significant over time. This conclusion still held after robustness tests such as selecting historical data as instrumental variables and selecting the "Broadband China" pilot project as a quasi-natural experiment. Eastern, non-resource and regenerative cities were better able to exploit the digital economy dividend and promote carbon emission reduction. The positive impact of the digital economy on carbon emission reduction had a threshold effect due to the difference in population size and innovation capacity of cities. The analysis of the mechanism showed that reducing energy consumption intensity, optimizing industrial structure, promoting technological progress and empowering digital infrastructure were important ways to achieve carbon emission reduction in the digital economy. For every 1% growth of the digital economy, the energy consumption intensity decreased by 0.154%, while the effects of industrial structure upgrading, technological progress and digital infrastructure empowerment increased by 0.835%, 1.032% and 0.351%, respectively.
2023 Vol. 43 (8): 4437-4448 [Abstract] ( 233 ) [HTML 0KB] [ PDF 628KB] ( 2967 )
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