The composition of PM_2.5 was monitored online continuously by using MARGA 1S Analyzer ADI 2080 in Nanjing from December 27, 2017 to January 5, 2018. Combined with meteorological elements and atmospheric environmental monitoring data, the time distribution and source characteristics of water-soluble ions in haze pollution process was investigated. The mass concentration of water-soluble ions in Nanjing during the haze pollution was 121.41μg/m³, 3.2 times of the level in clean days. The order of the average mass concentration of water-soluble ions in the haze pollution process was NO₃^- > SO₄^2- > NH₄⁺ > Cl^- > K⁺ > Ca²⁺ > Mg²⁺. SO₄^2-, NO₃^- and NH₄⁺ accounted for 91.97% of the total water-soluble ions concentration. The diurnal variations of water-soluble ions in haze days were all trimodal, while in clean days, Cl^-, SO₄^2- and NH₄^- were unimodal, Ca²⁺ was bimodal, K⁺ and Mg²⁺ were trimodal. With the aggravation of the air pollution, the proportion of total water-soluble ions in PM_2.5 was decreasing. When the air quality was excellent, the proportion was 95.93%, while it was 63.25% when serious pollution occurred. With the increase of pollution in haze days, the proportion of NH₄⁺ to total water-soluble ions was stable at around 23%, the proportion of SO₄^2- decreased slowly, and the proportion of NO₃^- increased continuously. The diurnal variations of NOR and SOR were bimodal in haze days, while in clear days, they were relatively stable. During the observation period, water-soluble ions were derived mainly from secondary conversion, coal ash, dust, and biomass combustion.

Characteristics and formation mechanism of a heavy air pollution event during the period from December 27^th to 31^st, 2017 in Tangshan, Hebei, China were investigated. Combined with the mass concentration of particulate matter, gaseous pollutant concentrations, carbonaceous species and meteorological data, the component analysis of PM_2.5 was conducted in detail for this episode. The results showed that the average mass concentration of PM_2.5 during this period was 154μg/m³ exceeding the secondary standard of daily average concentration of the ambient air quality standard (GB3095-2012). When the air pollution level was 5 and above, passed the level of heavy and above, the ratio of PM_2.5 over PM₁₀ became 0.7. The mass concentration of SNA accounted for 58.0% of PM_2.5, and the value of OC/EC was 4.1, which indicated that the secondary reaction of particulate matter and organic matter had a greater contribution in this pollution process. The local meteorological conditions, continuous uniform pressure field, the near-surface high humidity, light breeze and temperature inversion all played an important role in this heavy pollution event. Regional transmission was also an important contribsuting factor to this heavy pollution process.

The ground and vertical meteorological characteristics associated with 11atmospheric circulation types during autumns and winters (Nov.-Feb., 2013~2018) in Beijing was summarized. The circulation types were classified into five categories, and the influence of each category on the transport of air pollution as well as fine particulate matter (PM_2.5) pollution was discussed. Among five categories, Category I (including north (N) and northeast (NE) circulation types, which accounted for 28% of days) and Category Ⅱ (including northwest (NW) and anticyclone (A), which accounted for 33%) were favorable for air pollution diffusion, which were characterized by the dominant northwest winds with steady direction and high speed, as well as high planetary boundary layer (PBL) height. Category Ⅲ (including East (E), 7%) was dominated by southeast winds with variable directions and moderate speed within PBL, and provided moderate conditions for air pollution diffusion. Category IV (including southwest (SW), west (W) and south (S), 12%) and Category V (including southeast (SE), uniform pressure fields(UM) and cyclone (C), 20%) were unfavorable for air pollution diffusion, which were characterized by the dominant south winds with low speed within PBL, as well as the low PBL height due to strong temperature inversion in low atmosphere. The wind direction near ground was usually steady under Category IV, while varied greatly under Category V. The transport pathways of the air mass arriving in Beijing under different circulation types showed significant difference, thus, resulted in the changing of potential source regions contributing to air pollution in Beijing. PM_2.5 pollution was closely related to the atmospheric circulation types in autumn and winter in Beijing. PM_2.5 pollution was most likely to occur under the types of SW, UM, C, S and W (the average frequency of pollution is larger than 75%, the average frequency of severe pollution is larger than 42%), while the types of N, A, NE and NW were associated with low frequency of occurrence of PM_2.5 pollution. A higher proportion of the UM type was usually observed in the months with extremely severe PM_2.5 pollutions, while the proportion of the N type nearly doubled in the months with the lowest PM_2.5 level. In addition, the change of PM_2.5 concentrations sometimes lagged behind the change of circulation types.

As the farmland tractors (FT) have dramatically increased in Xinjiang autonomous region of China in the past decades, FT emissions have become one of the major air pollution sources across the entire region. The emission time series inventories of PM₁₀, PM_2.5, HC, NO_x and CO for FT in Xinjiang from 1993 to 2017 were established based on fuel consumption, and the evolution trends of these air pollutants were also analyzed. The list of impact factors of FT's emission mainly from diesel engines was constructed with the consideration of three aspects:economic development levels, FT's own attributes, and the scientific and technological development. Based on the rough set theory, a quantitative analysis of factors affecting pollutants' emission was also performed. The results showed that the total emission of all pollutants of FTs in Xinjiang had increased by more than 2times in recent 25 years from 1993 to 2017 with the annual growth rate of 3.67%, and the emission per ten thousand kilowatt had decreased by nearly 40.03%. It suggested that the emission standards for FTs proposed in recent years may played a substantial role. Second, the quantitative analysis of the impacting factors of pollution showed that the total FT power, the number of FTs, the area of ploughing, the area of sowing, the area of harvesting, the investment of agricultural machinery, the investment of fixed assets by farmers, and the emission per 10thousand kilowatt all had affected the emission with impacting factors of 0.2591, 0.2491, 0.0841, 0.0759, 0.0934, 0.0568, 0.0701, 0.0701, respectively. The affecting factors of economic development level, FT own attributes, and the science and technology on FT pollutants were 0.6350, 0.2530 and 0.1119, respectively. Third, the established mission inventory and the evolution trend can well reflect the status of pollutants emission from the agricultural machinery sector in Xinjiang. The results accurately reflected the influence of Xinjiang's social economic development, agricultural mechanization and scientific and technological progress on FT's pollutant emission.

The effect of the pore structure of polymeric resins on their adsorption kinetics was explored and Dual Resistance Model for predicting absorption kinetics of multiple components was established. The adsorption kinetics of individual toluene, cyclohexane and n-pentane as well as their dual or triple combinations on two polymeric resins were studied by the differential adsorption bed (DAB) method. Dual Resistance Model, which is a combination of barrier resistance at the micropore mouth and pore interior resistance, was effective for the fitting of adsorption kinetic data of single component, indicating that the adsorption diffusion resistance existed at the micropore mouth and the mircopore interior simultaneously. The adsorption kinetic curves of binary and ternary component VOCs on two resins can be predicted effectively by using the Dual Resistance Model as well as the extended Langmuir multi-component adsorption equilibrium equation. The average error between model prediction and experimental data were less than 17%. The competitive adsorption between the different components on the microporous resin was more significant than that on the macroporous resin and adsorption affinity of three VOCs on two resins had the following order:toluene > cyclohexane > pentane.

Seawater and atmospheric concentrations of C₂~C₅ non-methane hydrocarbons (NMHCs) were determined in the Yellow Sea and Bohai Sea during November 2014 with the preconcentration methods of purge-and-trap system and three-stage low-temperature preconcentration system combined with gas chromatography with mass spectrum detector. The sea-air fluxes of NMHCs and their atmospheric chemical reactivity were also studied. The average concentrations of ethane, propane, isobutane, n-butane, ethylene, propylene, 1-butene, isobutylene and isoprene in the surface water were 53.0, 49.4, 26.4, 29.2, 186, 62.7, 35.6, 89.9 and 42.4pmol/L, respectively, and the average volume percentages in the atmosphere were 0.043, 21, 0.36, 6.7, 7.5, 0.71, 0.12, 0.16 and 0.085×10^-9. Atmospheric concentrations of ethane, propane, isobutane, n-butane, ethylene, propylene, 1-butene and isobutylene exhibited strong correlations within each other in the atmosphere, and none of them correlated to isoprene. The study shows that the coast shelf seas of China might be an important sources of C₂~C₅ NMHCs. Through the calculation of the ozone generation potential and OH· potential consumption rate of NMHCs, ethylene, propylene, propane and n-butane were found to be the key active components of C₂~C₅ NMHCs in the atmosphere over the Yellow Sea and the Bohai Sea.

The investigation on adsorption mechanism of chlorine-modified activated carbon on elemental lead (Pb⁰) was conducted by density functional method using quantum chemistry method. In this study, we explored the effect of chlorine modification on adsorption of Pb⁰ by activated carbon surface, and the adsorption energy, key bond length, corresponding Mayor bond order and Mulliken atomic charge of Pb⁰ were acquired. Full-parameter geometrical optimization and single point energy were calculated at B3LYP/def2-SVP and PWPB95/def2-TZVP level. Results showed that the chlorine modification decreased the adsorption energy of Pb⁰ on activated carbon by 74.034kJ/mol for armchair char but it had little influence on Pb⁰ adsorption for zigzag char. Therefore, the chlorine modification would overall suppress the adsorption of Pb⁰ on activated carbon, but the adsorption type still belongs to chemical adsorption. The result agreed with the conclusion in regards to Pb⁰ adsorption energy on pure activated carbon and chlorine modified activated carbon using electronic density analysis and Mayor bond order analysis respectively. In addition, Mayor bond order analysis suggested chlorine atom would affect the Pb⁰adsorption via affecting carbon atoms, while rather than interacting with Pb⁰ directly. Furthermore, the atomic charge of Pb⁰ is correlated positively with the adsorption energy on activated carbon, and the higher atomic charge of Pb⁰, the larger adsorption energy of the corresponding adsorption configuration. Additionally, we found that the introduction of Pb⁰ could block the adsorption of another Pb⁰ on chlorine-modified carbon.

In July 2017, a dynamic chamber system, simultaneously recording air temperature, relative humidity and photosynthetically active radiation, was employed to study the emission of biogenic volatile organic compounds (BVOC) from desert grassland of Inner Mongolia. The results showed that Leymus chinensis and Agropyron cristatum growing in desert grassland emitted isoprene, α-pinene, β-pinene, α-phellandrene, 3-carene, α-terpinene, p-cymene, limonene, γ-terpinene, terpinolene, ocimene and camphene, with the average emission fluxes of (578.76±92.39), (35.51±20.23), (23.62±5.62), (380.48±206.97), (15.70±4.72), (36.21±10.53), (62.46±10.36), (36.63±22.83), (85.44±48.33), (5.59±5.33), (17.62±3.32), (173.39±201.97)μg/(m²·h) from Leymus chinensis and (587.36±298.57), (7.24±0.28), (80.09±0.32), (204.49±122.10), (4.64±0.83), (9.96±3.32), (18.86±5.73), (4.49±4.37), (63.02±27.51), (7.26±5.09), (23.06±1.86), (32.30±26.29)μg/(m²·h) from Agropyron cristatum, respectively. The changes of BVOC emission fluxes were consistent with that of air temperature and photosynthetic effective radiation, but the influencing factors were different from plant to plant, and the emission processes were complex. The emission fluxes of BOVCs peaked at 11:00 or 15:00, except isoprene emission from Agropyron cristatum were higher at 15:00 and 17:00.

Carbon nitride nanosheet (CNNS) was synthesized via a facile thermal exfoliation approach and employed for adsorption removal of gaseous elemental mercury (Hg⁰) at low temperature. The sorbents were characterized by nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that CNNS performed well toward Hg⁰ adsorption with a removal efficiency around 54.2% at 120℃. The Hg⁰ removal efficiency of CNNS could be greatly enhanced by Cu-modification to more than 82.3% at the temperature range of 40 to 240℃ due to the intimate contact of copper and carbon nitride. Calcination temperature had a big influence on Hg⁰ capture ability of Cu-modified CNNS. The optimal annealing temperature was 200℃. CNNS could be efficiently activated by Cu-modification and its Hg⁰ oxidation ability was enhanced, probably attributed to the Mott-Schottky electron transfer effect between Cu ions and carbon nitrides. SO₂ and H₂O can inhibit Cu-modified CNNS's Hg⁰ removal performance.

By combining Linear Mixed Effect (LME) model and Bayesian Maximum Entropy (BME) method, ground-level PM_2.5 from October 2015 to March 2016 in Pearl River Delta region were estimated in this paper by AOD, NDVI and meteorological data. The results showed that the prediction accuracy of LME+BME method were greatly improved compared with that of the LME method. The cross-validation R² of LME+BME model was 0.751, and root mean squared prediction error (RMSE) was 6.886μg/m³, the mean prediction error (MPE) was 4.52μg/m³, while R²=0.703, RMSE=7.546μg/m³, and MAE=4.927μg/m³ for the LME method. The high PM_2.5 concentration was mainly located in Guangzhou, Foshan, Dongguan, and the low PM_2.5 concentration was mainly distributed in Zhaoqing, Huizhou, Jiangmen. In terms of seasonal variation, PM_2.5 pollution was more serious in mid-October in 2015, late November in 2015 and late March in 2016, while it was relatively low in early October in 2015, early December in 2015 and late January in 2016.

In order to investigate the emission rate of soil CO₂ and its influencing factors under different plant communities in arid saline lakes, four plant communities including Aeluropus pungens, Iris tectorum, Achnatherum splendens, Lycium ruthenicum Murr and abandoned land in Danbancheng Saline Lake were selected. The soil CO₂ emission rates, under the five plant communities were measured from April to December, 2016 using the LI-8100A. Meanwhile, the soil temperature in 5, 10 and 15cm depth, soil water content and electric conductivity were also measured. Results showed that the diurnal variation of soil CO₂ emission rate under Aeluropus pungens showed obvious single peak, the highest emission rate happened in July around 14:00. For other plant communities, the emission rates showed the sing peak in 12:00~14:00 in all months except July during which the emission rates had two peaks in 10:00 and 14:00 to 16:00. There were significant difference in the emission rate between different plant communities and among different months under the same plant community (P<0.001). During the research period, the cumulative soil CO₂ emission was highest under Achnatherum splendens (2508.01g/m²), followed by abandoned land (2235.01g/m²), Iris tectorum (1903.03g/m²), Lycium ruthenicum Murr (1690.27g/m²), and Aeluropus pungens (550.34g/m²). The correlation between soil CO₂ emission rate and soil temperature in 15cm depth under Aeluropus pungens was significant (R²=0.739, P<0.05), and it was sensitive to the changes of soil temperature in 15cm depth. Under other plant communities, soil CO₂ emission rate have highest correlations with soil temperature in 5cm depth (R²=0.708~0.821), indicating they are sensitive to the changes of soil temperature in 5cm depth. Plant communities had great effect on the temperature sensitive of soil CO₂ emission (Q₁₀) with largely ranging from 0.60 to 21.74. Values of Q₁₀ was significantly different from April to December. The greatest Q₁₀ under Aeluropus pungens was found at June (7.97), while the highest values under other plant communities were found at November or December:Iris tectorum (21.74), Achnatherum splendens (13.21), Lycium ruthenicum Murr (18.23) and abandoned land (7.65). Regression analysis results showed that the correlation between the CO₂ emission (C_f) and the soil moisture was low, the correlation with soil electric conductivity could be modeled (log_eC_f=-0.149EC+0.943). Our result also indicated that salinity was an important factor affecting soil carbon emissions among the saline lake. To conclude, the soil carbon process of the saline lake ecosystem in the arid area and the influence of soil salt content on the carbon emissions of the saline lake ecosystem should not been ignored when considering the carbon budget and carbon cycle of the terrestrial ecosystem.

The impact of inland large water bodies on the air environment of inland cities was investigated based on the method of CFD (Computational Fluid Dynamics) simulation with KRB coordinate transformation. Both urban heat island circulation and lake wind circulation were modelled by the CFD methodology, and they were verified by comparing with the reduced-scale water tank experiment. The urban island circulation was heavily influenced by the size of the water body and its distance to the urban center. It was shown that the larger the lake area, the greater offset of the observed urban thermal plume; whereas, when the distance from the city center to the water bodies increased, the offset of the heat island plume near the ground reduced. When the lake was located close to the city, lake-breeze and the city airflow put aiding effect, i.e., generating strong aiding circulations. However, as the lake was further away from the city, opposing effect was found between the lake wind and the urban heat island circulation. Cooperating aiding effect could be found between the diverging flow and lake wind beyond of the plume.

From 16 to 21December 2016, the Beijing-Tianjin-Hebei region experienced a large-scale heavy pollution process. By using the pollutant concentration monitoring data, weather charts, the synoptic causes of the heavy air pollution were investigated in the present paper. The sources of PM_2.5 pollution in the main cities of Beijing, Tianjin and Hebei region were also analyzed quantitatively by using the Nested Air Quality Prediction Modeling System (NAQPMS). The results showed that it blew straight west wind in 500hPa accompanied with the warmer air in the early stage. Subsequently, it turned to south airflow ahead of trough accompanied with warm ridge, getting warmer and wetter substantially. Correspondingly, the ground pressure gradually decreased and the convergence increased continuously. In the vertical direction, the inversion layer continued to rise and thicken, the warm advection in the middle and lower layers was obvious, and the vertical shear of the wind was small. In summary, the atmosphere was in a state of extremely static stability, which led to a long and heavy pollution process in North China. During the period of air pollution, the local contribution of PM_2.5 pollution in major cities of Beijing, Tianjin and Hebei region was 40%~60%. The local contribution of PM_2.5 in Beijing was 48%, in which Beijing was mainly affected by the southwest transport channel along the east side of Taihang Mountain from 16 to 17December, then as the result of the decreased wind speed afterwards, local and surrounding cities contributed more.

The spatial-temporal pattern of PM_2.5 in Chinese prefecture-level cities over 1998~2016 has been explored in this study based on Kernel Density Estimation (KDE), Global Spatial Autocorrelation, Local Spatial Autocorrelation, Hotspot Analysis and other methods with the data of PM_2.5 concentration extracted from the 1998 to 2016 global PM_2.5 concentration raster dataset at prefecture-level city. The results showed that first the concentration of PM_2.5 in China has been rising with an average annual increase of 0.55μg/m³; as a whole from 1998 to 2016. Its changing trend could be divided into two stages:rapid growth from 1998 to 2007 and decline-growth-decline fluctuations from 2008 to 2016. Geographically, eastern China and central China experienced similar changing trends, while western China experienced a moderate changing trend, and the changing trend of northeastern China was more dramatic. Second, from 1998 to 2016, the peak of the core density curve gradually shifted to the right, indicating that PM_2.5 pollution in Chinese prefecture-level cities was generally increasing. The shifting was far more substantial in eastern and central China than in western China. Third, PM_2.5 pollution presented a significant positive spatial correlation. The high-value clusters were concentrated in most parts of Shandong, Henan, Hebei, Jiangsu, Anhui, Hunan, Hubei, and eastern Sichuan. The number of high-value cluster cities had increased from 1998 to 2007 with the peak achieved in 2007. The high-value areas westward and southward during this period. After 2007, the number of high-value agglomerated cities had gradually decreased, and its southern boundary gradually moved northward. Low-value city clusters were concentrated in Inner Mongolia, northwestern Heilongjiang, Xinjiang, Tibet, Taiwan, Hainan, Fujian and other regions, and the number of low-value cluster cities showed an increase first and then decreased trend with annual variations.

In order to further enhance the immobilization capability and biodegradability of functional bacteria in bio-enhanced activated carbon process (BEAC), pore structure regulation of coal-based activated carbon was conducted by an innovative agglomerated procedure including CO₂ oxidation and depth-activation. New type carbon XHIT was consequently prepared in the present work. Characterization results suggested that the volume (0.7041cm³/g) and ratio (63.95%) of meso-porous structure in carbon XHIT were significantly improved. Immobilization capability of functional bacteria on surface of XHIT was also improved synchronously during the pore-structure regulation. The initial immobilized biomass reached up to 9.13mmol/g(P), and its multiplication rate was 2.123mmol/(g·d)(P). After depth-activation process, surface oxygen content of XHIT was improved to 9.96%, which caused the significant reduction of dissolved oxygen affinity ((0.42±0.07)mg DO/L) during the adsorption process. And this phenomenon also enhanced the dissolved oxygen utilization efficiency in biodegradation (91.28%). Based on carbon XHIT, BEAC pilot process system was established for purification of source water from Songhua River. Results shows that the removal efficiency and cumulative uptake of organic-pollutants represented by COD_Mn reached to (70.65±15.22)% and 94655.50mg·COD_Mn/(kg·Carbon), respectively, with the KBV of 39.50m³/kg.

The characteristics of phosphorus adsorption were studied by using magnetic modified-lobster shell. The results showed that the highest efficiency of phosphorus removal occurred at the adsorbent dosage of 4g/L, and above 91.6% phosphorus was removed in the wastewater with the phosphorus concentration lower than 20mg/L by magnetic modified-lobster shells, and their ability of removing phosphorus was suitable to a wide range of pH. The co-existing ions (Cl^-, SO₄^2-, NO₃^- and HCO₃^-) had a little influence on the phosphorus removal ability, and whereas HCO₃^- ion had a slightly negative effect on phosphorus adsorption. Freundlich equation could well describe the adsorption behaviour of phosphorus of magnetic modified-lobster shells, and the adsorption process followed the quasi-second-order kinetic model. Thermodynamic analysis showed that the adsorption process was spontaneous. The main mechanisms of phosphorus adsorption by magnetic modified-lobster shells were ligand exchange, electrostatic interaction and surface precipitation according to X-ray diffraction and FTIR analyses.

Concentration of twelve metals, Hg, Mn, Fe, Al, Zn, Ni, As, Pb, Cr, Cd, Co and Cu from thirty samples collected from groundwater around iron mine in Hongyang, Liangan, Tingle and Kongjia villages in Chongzuo city were measured and analyzed to investigate their distribution characteristics and the human health risks. The distribution characteristics of these elements were analyzed using multivariate statistical analysis method and the health risks caused by metals were assessed using human health risk assessment model. The average concentrations of Zn and Fe ((250.32, 103.96μg/L) were higher than others. Concentrations of Hg, Mn, Fe, Al and Zn exceeded the Quality Standards for Groundwater (GB/T 14848-2017). The highest concentrations of Fe, Mn and Al were mainly located in Hongyang and Tingle, the highest concentrations of Zn and Hg were mainly located in Hongyang and Liangan. Multivariate statistical analysis indicated that Fe, Mn, Al, Pb, As and Co mainly originated from iron mining, while Cu, Zn, Cr and Ni were mainly related to the lead-zinc mine and regional geological background. Hg mainly originated from contaminated sugar and paper mills' contamination and Cd mainly originated from natural sources. The results of health risk assessment indicated that the total risks of metals in Liangan is the highest, which were 8.82×10^-5a^-1.Children had greater health risks than adults. The health risks of metals through drinking pathway were 2~3 orders of magnitude higher than the values caused by dermal contact pathway. Carcinogenic risks caused by Cr were higher than the maximum allowance levels (5.0×10^-5a^-1). The non-carcinogenic risk levels of the metals were 10^-14~10^-9a^-1, which were 4~9 orders of magnitude lower than the maximum allowance.

Graphene oxide (GO) was used to enhance denitrification performance of anammox bacteria. Batch experiments were executed to explore effect of GO on anammox bacteria. The results showed anammox bacteria had the best nitrogen removal performance when the concentration of GO was 0.15g/L, and the total nitrogen removal rate was 18.6% higher than blank group. When GO concentration reached 0.2g/L, anammox bacteria activity was inhibited, and the total nitrogen removal rate was reduced by 26.0% compare with the blank group. A long-term experiment was operated to ident the effect of GO on anammox bacteria by set control group. The results showed the average total nitrogen removal rate of the R2 reactor with GO was 85.3%, 83.2% and 81.1% and 80.8%, respectively, which was higher than the R1reactor without GO. The kinetics characteristics of nitrogen removal in a single cycle of the R2 reactor were evaluated. The modified Boltzmann and Gompertz model were found to be the appropriate models to describe the denitrification performance of the R2 reactor in a single cycle. Moreover, the formula to predict the total nitrogen effluent concentration and removal rate at any time in the cycle was obtained.

To explore the effects of different alkalinity substances (Na₂CO₃, KHCO₃, NaHCO₃) and concentration ranges (2000, 3000, 4000mg/L (as CaCO₃)) on the middle-temperature anaerobic digestion system, a static batch semi-continuous stirred tank was used in the experiment. The comprehensive reactor operation and microbial high-throughput sequencing analysis showed that Na₂CO₃ could promote the hydrolysis and acidification process in three different types of alkalinity, while NaHCO₃ was more prominent in gas production and reduction. It indicated that Na₂CO₃ was more likely to promote hydrolysis and acidification in the limiting stage compared to other samples, when the alkalinity of the system was adjusted. Under different concentrations, the hydrolysis capacity was enhanced by increasing the concentration of added basicity, which led to the deterioration of the dehydration performance, while the Volatile Fatty Acids changed little, and the excess basicity will reduce the gas production and reduction of the system.

Bi₂O₃ photocatalyst with plate-like morphology was successfully prepared by the method of chemical precipitation which using Bi(NO₃)₃·5H₂O as the source of bismuth, HNO₃ as solvent and HTMA as precipitants, respectively. The morphology, thickness, crystal form and specific surface area of the as-prepared Bi₂O₃ were characterized by SEM, XRD and BET respectively. Furthermore, the photocatalytic performance of the materials was tested by UV-Vis diffuse reflection and photochemical reaction apparatus. The results showed that the obtained Bi₂O₃ photocatalyst with plate-like morphology has good morphology, uniform thickness, a-Bi₂O₃, stronger absorbent for visible-light and exhibits good photocatalytic property. Under the simulated visible light of 300W, the degradation rate of tetracycline wastewater can be reached to 82.6% after 3.0h, which is much higher than that of commercially nanoparticles Bi₂O₃.

To investigate the mechanism of nitrogen uptake and metabolism in U. prolifera, the distribution and migration of different forms of nitrogen in culture media and algea cells during the growth-decay process was studied with continuous culture experiments. U. prolifera absorbed NO₃^--N (17.37μmol/(g·d)) into the cell during the growth phase while released NH₄⁺-N (0.84μmol/(g·d)) to the extracellular during the decay phase. In algae cell, up to 73.75%~92.15% of dissolved inorganic nitrogen (DIN) was NO₃^--N during the growth phase, while 60.87%~92.13% was NH₄⁺-N during the decay period. The concentration of dissolved organic nitrogen (DON) in the culture media increased continually during the culture period, with < 1kDa component accounting for 64%~98% and > 1kDa component accounting for 2%~36%. The average migration rate of DIN was about 8.96μmol/(g·d), and the average release rate of DON was about 59.57μmol/(g·d). Nearly 60% DIN was converted into DON and secreted extracellularly, most of which was < 1kDa component. It can be speculated that the outburst of U. prolifera impacts the structure of biological elements significantly on the monthly scale.

The long-term effects on ammonia-oxidizing bacteria (AOB), filamentous bacteria and microorganism community structures in partial nitrification sludge was investigated by adding a pretreatment unit of free nitrous acid (FNA) in the sequence bath reactor (SBR) for three days at 1.2mg HNO₂-N/L for 4.5. The results showed that FNA had the short-time effect on AOB, Candidatus_Microthrix and Cytophagaceae of the dominant filamentous bacteria were also decreased from 5.1% and 1.1% to 0.78% and almost invisible. Sludge volume index (SVI) maintained at 110mL/g dropping from 281mL/g, and the nitrite accumulation rate (NAR) was kept at around 90%, indicating the partial nitrification was not undermined. Furthermore, High-throughput sequencing results showed that the diversity and uniformity of microorganism community decreased. However, the proliferation of Thauera and Ottowia increased to 5.58% and 7.82%. Simultaneous nitrification and denitrification (SND) had significant effects, and the total nitrogen removal rate was nevertheless maintained more than 60% even only with partial nitrification.

Regarding the changing nature of the organic load in decentralized rural wastewater, the ability of the anaerobic-anoxic-aerobic membrane bioreactor (A²O-MBR) with suspended carriers to resist the high organic load shock was studied. The effects of high organic load shock on the pollutant removal, properties of suspended and attached sludge as well as membrane fouling were investigated. The results showed that the pollutant removal was stable during high load shock. The removal rate of ammonia nitrogen decreased from 99.1% to 78.5% on the third day after the shock, and the ammonia nitrogen concentration in the effluent was higher than 5mg/L. Then the removal rate of ammonia nitrogen recovered back to 97.6%. The adenosine triphosphate (ATP) content of suspended and attached microorganisms, the attached biomass and the content of extracellular polymer (EPS) increased. The membrane fouling became more serious, and EPS content of the membrane-fouling layer was increased significantly during the shock period. The solar-powered A²O-MBR system can cut down 10% of carbon emissions.

A biofilm reactor coupled with embedded ferric tannate was used to treat low C/N ratio wastewater and its nitrogen removal performance was investigated. The biological nitrogen removal process and the corresponding functional bacterial populations in the biofilm were also analyzed. The enhanced nitrogen removal by ferric tannate and its mechanism were also discussed. The results showed that the efficient nitrogen removal for low C/N ratio wastewater could be achieved in the biofilm reactor coupled with embedded ferric tannate. When the influent C/N ratio was 1:2.7, the average total nitrogen (TN) removal efficiency was 80.0%, and the average TN loading rate removed was 1.38kg/(m³·d). The dominant biological nitrogen removal process was converted from simultaneous nitrification-denitrification to simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) process in the biofilm reactor when the influent C/N ratio decreased. As a result, the contribution of ANAMMOX process to TN removal increased up to 76.2% in the biofilm reactor. The populations of nitrosate bacteria and anammox bacteria became dominant for biological nitrogen removal. The ammonia nitrogen and nitrite nitrogen could be removed simultaneously by embedded ferric tannate due to the adsorption-catalytic ammonia oxidation process after biological treatment, resulting in further improvement of TN removal. Therefore, the enhancement of SNAD process by ferric tannate in a biofilm reactor is a new and effective solution for efficient nitrogen removal of low C/N ratio wastewater.

The current study mainly discussed the electrochemical reduction of ferrihydrite mediated by anthraquinone (AQS) in the "electrode-AQS-ferrihydrite" reaction system, and the kinetic characteristics and mechanism of the interaction. Compared with ordinary glassy carbon electrode, the sensitivity of the electrochemical reduction reaction occurring on the surface of the carbon felt electrode had been significantly improved under ultrasonic opening condition. When the applied voltage was -0.7V (vs Ag/AgCl), AQS could be completely reduced. On the optimal experimental conditions, AQS could participate in the electrochemical reduction process of ferrihydrite as a redox mediator. When the amount of AQS increased from 0.005mmol/L to 0.035mmol/L, the reduction ratio of the absolute amount of ferrihydrite rose from 10.4% to 35%. The time course of the intermediate product (AQS_oxi) concentration (C_AQSoxi) showed a typical characteristic of function model curve derived from consecutive reactions. As the reaction time (t) increased, C_AQSoxi grew rapidly in the initial stage; and subsequently, when reaction time (t) reached a certain level, C_AQSoxi had experienced rapidly declines to various degrees, and the Adj.R² in the fitted model could be high enough to 0.9990.

With perfluorooctane sulfonate (PFOS) as the targeted matter and Bovine serum albumin (BSA) as the typical organic protein, we investigated the effects of BSA and its concentration, as well as ionic strength and ionic types when BSA coexisting with inorganic ions in feed water on PFOS removal by polyamide nanofiltration membrane in this study. The results showed that a significant improvement in PFOS removal rate was observed in the presence of BSA. The higher the concentration of BSA, the higher PFOS removal rate was. When BSA and inorganic ions coexisted in the feed solution, PFOS removal rate increased with the increase of ionic strength. This may be because BSA would not only absorb some PFOS, but also cause membrane fouling. The higher the BSA concentration, the more serious membrane fouling was. Consequently, the screening ability of fouled membrane and the electrostatic repulsion force between the membrane surface and PFOS were enhanced. Thus, the removal rate of PFOS increased. The existence of ions reduced the electrostatic repulsion force between BSA and the membrane surface, which resulted in thicker BSA fouling layers and enhanced membrane sieving capacity. Additionally, our experiments showed that the ability of Ca²⁺ to improve PFOS rejection was better than that of Na⁺.

The research was carried out in an actual full-scale, non-circulated experimental platform. The effect of Epoxy Resin coating on biofilm on ductile cast iron pipes was studied by analyzing the physicochemical characteristics and microbial community composition of biofilms. The results revealed that the additional epoxy resin coating, compared with cement-mortar lined ductile cast iron pipes, can reduce the attachment of solids and had a positive impact on the microbial abundance and negative impacts on the community composition of biofilms. The total bacteria were 4.01×10⁴copies/cm² and heterotrophic bacteria were 1.40×10CFU/cm² in the biofilms. Therefore, Cement-mortar lined ductile cast iron pipes with epoxy resin coating were better in practical applications.

Zn/Ni/Cu-BTC, a new porous material with three metals and one single-ligand, was synthesized by a hydrothermal synthesis method. The material was characterized by N₂ adsorption-desorption, SEM and XRD methods. Its adsorptive performance for anion Congo red was investigated at the normal pressure and temperature (25℃, 1ATM) with batch experiments. The result showed that the Congo red uptake capacity increased more than 98% from 630mg/g to 1250mg/g. The adsorption process of Congo red onto Zn/Ni/Cu-BTC could be effectively described by the pseudo-second-order kinetic model and Langmuir adsorption model.

The effect of ball milled zero-valent iron (BZVI) on As remove was studied under different concentrations of NO₃^-, SO₄^2-, H₂PO₄^- and SiO₃^2-. The oxidation capacity of BZVI on As(Ⅲ), transformation between As(Ⅲ) and As(V), and the corrosion products of BZVI affected by these anions were studied as well. Arsenic removal efficiency was not significantly changed under varied concentrations of NO₃^- and SO₄^2-. However aqueous As (V) ratio increased from 25.1% to 83.6% accompanied by the increase of H₂PO₄^-, while it decreased from 25.1% to 3.8% with the increase of SiO₃^2-. Results of scanning electron microscopy images and raman spectroscopy showed that H₂PO₄^- promoted the corrosion of BZVI, resulting in the enhanced As (Ⅲ) oxidation capacity. Besides under aqueous SiO₃^2- the formation of silica polymer or amorphous solid phase on iron surface mainly contributed to the weakened As oxidation and adsorption capacity by BZVI.

In order to better understand the formation rate and extent of submerged oil under the effect of SPM, this study selected three crude oils as test oils, which were taken from the Bohai southern oilfield (YYH), Liaohe Oilfield (LH) and Middle East (ZD), respectively. The interaction between kaolin and the test crude oils were studied. The results showed that the adsorption kinetics of the three test oils are basically similar, and the rate of sinking oils tends to be stable after exponential growth. The adsorption of the crude oils by kaolin satisfies the Langmuir isotherm, which belongs to monolayer adsorption. The saturated adsorption capacities of YYH, LX and ZD were 914, 1297 and 2083mg/g, respectively. When the concentration of SPM was 500mg/L, the maximum sinking rates of YYH, LX and ZD were 37%, 45% and 59%, respectively. Based on the adsorption mechanism, we discussed the distribution characteristics of dispersed oil droplets at the particle-water interface, and provided a model to calculate the relationship between the sinking rates and the concentration of SPM. This study can provide basic data and scientific basis for the study of numerical models of submerged oil formation and drift diffusion.

It was studied direct distribution characteristics of dissolved organic matter (DOM) in the treatment of domestic sewage by aeration pretreatment of improved soil infiltration system using three-dimensional fluorescence spectroscopy (3D-EEMs) based on parallel factor analysis (PARAFAC) and fluorescence regional integration (FRI), combined with principal component analysis, correlation analysis, cluster analysis and multivariate linear regression analysis. According to FRI, DOM in soil infiltration system could be divided into five fluorescent regions, including three protein-like regions (I, Ⅱ, IV) and two humus-like regions (Ⅲ, V). Along the vertical direction downward, DOM dissolution in soil infiltration system leaded to a significant negative correlation between TOT and TN, TP, NH₄⁺-N, COD, TOC and a significant positive correlation with EC, in which fluorescence region V had a significant positive correlation with NO₃^--N concentration and nitrogen removal. It was closely related to the composition of DOM. Four fluorescent components could be extracted from DOM species by PARAFAC, namely C1type fulvic acid and C2, C3, C4 type protein. F_max showed that the degradation order of soil infiltration system was C2 > C4 > C1, C3. It meant that tyrosine was the most easily degraded, followed by tryptophan-like substances and fulvic acid-like substances. Results from our multivariate linear regression analysis suggested that the concentration of water quality indicators such as TN, TP and COD could be indirectly expressed by F_max.

Refractory 3,4-dimethylaniline wastewater was studied for the oxidation mechanisms of various active substances generated in the HPECO process and the contribution degree (k_f/K) based on kinetics was utilized to evaluate the oxidation effect of each active substance. The results showed that the contribution degrees of active chlorines and hydroxyl radicals were respectively 89.03% and 6.24% and the contribution of hole and anode direct oxidation was negligible. The holes, hydroxyl radicals and free chlorine were determined respectively by the ways of melamine, dimethylsulfoxide and DPD and the results showed that the contribution degrees of holes and ·OH were decreased due to high concentration of sodium chloride and ·OH yield followed the zero-order kinetic law with the rate of 0.106mg/(L·min). Moreover, the cumulative concentration regulation of free chlorine was divided into three stages with the rate of 0.159mg/(L·min) in the third stage. Free chlorine only accounted for a small portion in active chlorines, while the oxidation of other chlorinated oxides and chlorinated free radicals played important roles. By GC-MS, UV-vis and TOC determination, it showed that in the initial 10.0min, the active chlorines attacked the side chains rapidly, so that 3, 4-DMA could be converted into benzaldehyde and other benzene derivatives. After 10.0min, the benzene derivatives were attacked towards the π bonds by ·OH and transformed into small molecules which could be finally mineralized.

The influences of hyperthermophilic pretreatment on physico-chemical properties and the formation of humic substances during the subsequent composting of pig manure and rice straw were investigated using an orthogonal experiment, The orthogonal experiment containing three factors, each with three levels, were conducted under different temperatures (75, 85, 95℃), heating intervals (2, 4, 8h) and ventilation (0.3, 0.6, 0.9L/kg TS·h), The results showed these three factors had different effects on the humification coefficient of the subsequent aerobic composting, The size of effects on the humification coefficient during the subsequent aerobic composting was in the order of pretreatment time, followed by temperature ventilation, The optimal hyperthermal pretreatment conditions were:95℃ for the temperature, 4h for the heating time and the aeration rate was 0.6L/kg TS·h, Compared with the control (CK), the humification coefficient of subsequent composting with pig manure and rice straw was increased by 119% under the optimal pretreatment conditions, The contents of total humic substance and humic acid were increased by 105% and 116%, respectively, while the fulvic acid content was decreased by 17.2%, Based on the variations of the physico-chemical characteristics before and after hyperthermal pretreatment, the results suggested that the hyperthermal pretreatment could promote the degradation of macromolecular organic matter into soluble organic carbon and degrade lignocellulosic components into to polyphenols, The precursors, such as the reduced sugars and amino acids, were also increased, which would in turn facilitate the formation of humic substances in composting.

Using the freeze-dried sludge of A²O-MBR process as raw material, we firstly obtained the crude lipid in the sludge by Soxhlet extraction. Then the crude lipid was eluted in a sequence of petroleum ether-ethyl acetate 100:1, 10:1 and 7:3 (V/V) by silica gel column chromatography. Compared the eluent with ceramide standard by thin layer chromatography, it was proved that the appropriate elution gradient was petroleum ether-ethyl acetate 7:3 (V/V). Through Q Exactive bench quadrupole orbitrap high-resolution mass spectrometry, the peak area ratio of ceramide was increased from 60.88% to 98.349% in the process of column chromatography. When the sludge of A²O process was used as raw material in the same experiment, the peak area ratio of ceramide was increased from 79.06% to 94.15%.

There has been a recent focus on microplastics (<5mm) because of their presence in different environmental media. The spatial and temporal distribution of microplastics in the surface sediments of the Changjiang Estuary were investigated in March and July 2017. Sampling was conducted at 17 stations covering the north passage and south passage of the Changjiang Estuary, East China Sea and Hangzhou bay. Among these sampling stations, the highest concentration of microplastics was (39.33±14.34) particles/kg (DW) in the Hangzhou bay in summer. There was no significant difference in spatial distribution of microplastics. The amount of precipitation was highly related with the abundance of microplastics, which showd higher concentrations in summer than in spring. The size, color, shape and composition of microplastics were classified. Attenuated total reflectance-Fourier transform infrared spectrometry showed that there were several types of microplastics existing in sediments, including polyethylene, polypropylene, polyvinyl chloride, polyamide, and polystyrene, among them, polyethylene was the main type. The method of pollution load index was used to assess the degree of microplastic pollution. Overall, the Changjiang Estuary-Hangzhou bay and its adjacent areas were less polluted by microplastics.

The contamination status of polycyclic aromatic hydrocarbons (PAHs) and the spatial distribution of ∑₂₅ PAHs and ∑_7carc PAHs were investigated based on 39 surface soil samples collected in May 2015 from the Yellow River Basin. The sources of PAHs were obtained by the isomer ratio method and principal component analysis method, and the health risk assessment of PAHs was evaluated by the BaP toxic equivalent and the excess lifetime risk model for cancer (ELCR). The results showed that the concentrations of mesenteric twenty-five PAHs in the surface soil ranged from 18.23 to 6805.49ng/g with an average value of 343.764ng/g; and the concentration of ∑₇ care PAHs ranged from 2.23 to 2796.34ng/g with an average value of 126.6ng/g. In general, the concentration of PAHs was higher in the middle and upper stream areas than in the downstream areas. In the majority of samples, we found that Ant/(Ant+Phe)<0.1, 0.2-6~10^-4, a level having potential health risks. While the value of ELCR in Xiangtang was higher at 10^-3, a level posting relatively high health risks.

The concentration of Pb, Cd, Zn, Cu, As and Ni in soils and dominant vegetables were determined based on the soil and vegetable samples collected from a representative zinc-smelting region in Northwest of Guizhou province. Both single factor pollution index and comprehensive pollution index methods were used to assess the concentration of heavy metals in soils and vegetables, and their potential ecological risks and health risks to adults and adolescents were also analyzed by the potential ecological risk index (RI) and target hazard quotient (THQ) methods. The results showed that the soils in the zinc-smelting area were contaminated by heavy metals and Cd contributed the most to the integrated pollution index; high ecological risks were imposed by Cd and there were 2.04%, 14.3%, 35.7% and 48.0% of sample sites in each category, decided according to the potential ecological risk index, of low, medium, high and extremely high risk, respectively. Among vegetable samples, the potatoes were heavily polluted and kidney beans were moderately polluted. Moreover, the comprehensive health risk index analysis suggested that the eating of vegetables grown in sample areas could cause serious potential health risks for adults and adolescents.

Origins of n-alkanes in surface soil from permafrost regions in the northern part of the Tibetan Plateau were studied by the distributions of n-alkanes, and the δD values of individual n-alkanes. That the distributions of the n-alkanes showed bimodal and trimodal patterns, suggesting that they were derived from multiple sources. The long-chain n-alkanes were mainly derived from higher terrestrial plants. Those of odd carbon number (C₂₅~C₃₃) were lighter than those with even carbon number, which might be caused by different biosynthetic pathways. Cluster analysis indicated that the medium-chain type I n-alkanes (C₂₁~C₂₄) were mainly derived from higher terrestrial plants, and the medium-chain type Ⅱ n-alkanes might have originated from microorganisms such as bacteria. The medium-chain n-alkane δD values of samples FHS-10, TG2-10and TG3-10were the lightest, due to both the light δD values of water and bacteria or other microorganisms.

Enhanced phytoremediation with the involvement of microbes and chemicals has become an alternative technique to remediate the contamination of heavy metal in soils. The combination of 0.3% sulfur and three levels of actinomycete Act 12 enhanced phytoremediation has been experimented to remediate the Cd-contaminated soil by employing Brassica juncea, a Cd-tolerant plant. The Cd accumulation in plant root and shoot part, antioxidant enzyme activities and plant root activity were measured to explore the potential mechanisms. The results showed that the combination of 0.3% sulfur and 2.0g/kg Act12 addition significantly reduced Rhizosphere pH by 14.5%. By comparison, the combination of 0.3% sulfur and 1.5g/kg Act12 addition treatment dramatically increased Cd accumulation in plant shoot by up to 79%. Act12 addition positively enhanced plant antioxidant system, and the values of CAT, POD, and SOD reached the peak in the treatment with a combination of 0.3% sulfur and 1.0g/kg Act12. Additionally, Act12 addition boosted plant root activities and reduced the content of MAD. Our study indicated that both sulfur and actinomycete Act 12 can enhance the absorption capacity of Cd by Brassica juncea, and the combination of 0.3% sulfur and 1.5g/kg Act12 addition achieved the best results in our experiments.

To clarify the characteristics of soil N₂O emission and identify the main factors under aerated irrigation (AI), the soil culture experiments were conducted at 2 irrigation levels with upper soil moisture limit as 70% and 90% of field capacity and 2 dissolved oxygen (DO) levels at 5 and 40mg/L. Soil N₂O emission fluxes were monitored using static chamber-gas chromatography method and the copy number of nitrification and denitrification gene were determined using the real-time quantitative polymerase chain reaction (qPCR) technique. In addition, the main factors on soil N₂O fluxes were analyzed, including soil water filling porosity (WFPS), DO, redox potential (Eh), mineral nitrogen content (NO₃^--N and NH₄⁺-N), as well as the abundance of soil ammonia-oxidizing bacterial (AOB) and ammonia-oxidizing archaea (AOA) and denitrifier genes (narG and nosZ). Results showed that soil N₂O flux increased from the beginning, peaked at 1d after irrigation, dropped in the following 3days, and then stabilized. An increase of aeration and irrigation amount resulted in the increase of average values and peak values of soil N₂O fluxes. Irrigation caused an increase of WFPS, while a decrease of soil DO and Eh. Aeration treatments increased soil DO concentration and Eh (P<0.05), improved soil aeration. However, aeration treatments showed no significant impact on WFPS. The WFPS, Eh and NO₃^--N content were the main physical, chemical influencing factors driving soil N₂O emission under AI. The AI significantly affected AOA copy numbers. In addition, soil N₂O fluxes were significantly correlated with AOA copy number (P<0.05). The results could provide scientific support for the influential mechanism of AI on soil N₂O and the farmland N₂O emission management.

3 universal green infrastructures (green roof, vegetative swale and permeable pavement) and 2 grey infrastructure mitigations (large diameter tube & reservoir) were selected to design 9 types of storm water drainage system modification scenarios in Fuzhou University campus. Under different extreme weather conditions (3 recorded rainfall events with different duration), SWMM model was used to analyze urban stormwater and flood control effect under different simulation scenarios (SS1~SS9). The control effect included runoff depth, node J8 flood flow and flood time, peak time and full flow time in C8 pipeline. The simulations results showed that simulation scenarios including green infrastructure had better control effect. Compared to other simulation scenarios, combinations of green roofs, vegetative swales and continuous permeable pavement systems (SS7) exhibited the best control effect on runoff depth under 3 rainfall events, the reduction ratio under the middle duration rainfall event was the highest, reaching 78%. While combinations of green roofs, vegetative swales, continuous permeable pavement systems and large diameter tubes (SS8, with the characteristics of infiltration, retention and quick drainage) displayed the best control effect on node J8 flood flow and flood time under 3rainfall events, reaching 100%. On the pipe flood control aspect, three combinations including green roofs, vegetative swales, continuous permeable pavement systems (SS7, SS8 and SS9) had a better effect on peak flow and full flow time in C8 pipeline than other simulation scenarios. Combinations of green roofs, vegetative swales, continuous permeable pavement systems and reservoirs (SS9) had the minimum full flow time and latest peak time in the short duration rainfall event. Combinations of green roofs, vegetative swales and continuous permeable pavement systems (SS7) had the minimum full flow time and latest peak time in the long duration rainfall event. Three combinations (SS7, SS8 and SS9) had no distinct differences on pipeline flood control in the middle duration rainfall event.

Focusing on the Inner Mongolia Autonomous Region, we conducted a comprehensive, qualitative and quantitative analysis on characteristics of the hiatus in temperature increase across the study area, as well as the responses of the hiatus to changes in influencing factors. Several statistical methods, such as the central cluster method and the M-K detection method, were applied in our investigation to the global large-scale spatial data sets (e.g., Pacific Decadal Oscillation (PDO) and the Multivariate ENSO Index (MEI)), and regional meteorological records (including average minimum temperature, average temperature, average maximum temperature, wind speed and atmospheric pressure) from 1951 to 2016 from 70 different weather stations. The results indicated that, for all sub-regions of the study area, abrupt changes in three temperature measurements occurred from 1981 to 1993, followed by a warming hiatus from 1998 to 2008. The degrees of correlation between the temperature and its influencing factors were different for different temperature measures, which also varied by sub-region. For example, the average minimum temperature had the strongest correlation with AMO, PDO, MEI, and total solar radiation. The correlation weakened the average temperature, and was the weakest for the average highest temperature. The temperature in the western sub-region was closely related to AMO, PDO, MEI and total solar radiation, whereas the temperature in the middle sub-region was closely related to AMO and wind speed. As a whole, from the 1990s to the 2000s, a time period that was characterized by a weak increasing trend in AMO and a decreasing trend in positive PDO or negative PDO phases, both MEI and total solar radiation showed descending tendencies. At this time, after a long-term increasing/decreasing trend in wind speed, atmospheric pressure and relative humidity, there was a hiatus in the increase in sub-regional temperature. For example, when the increasing trend in AMO slowed, wind speed declined continuously for 8~13a until its slope reached -0.26 to -0.11m/(s·10a), and the increase in average temperature showed a hiatus. Among the three temperatures, the average minimum temperature was most sensitive to changes in the three influencing factors, and the average temperature had a weaker sensitivity. The warming hiatus was a compound result of various factors. This study supplemented the research regarding the mechanisms behind the warming hiatus and provided referencing values for climate change and disaster prevention.

The concentrations of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dissolved methane (CH₄) were measured in situ in the Yellow Sea and Bohai Sea from December 2017 to January 2018 to study their distributions, correlations and the air-sea fluxes of DMS and CH₄. In addition, the influences of DMSP degradation on the productions of DMS and CH₄ were also studied through incubation experiments. The average concentrations of DMS, DMSPd, DMSPp and CH₄were (1.39±1.21), (2.87±1.54), (5.59±4.64) and (6.91±2.77) nmol/L in the surface water, respectively. The horizontal distributions of DMS, DMSP, and chlorophyll a (Chl-a) exhibited the same pattern of decreasing from inshore to offshore. The vertical profiles of DMS and DMSP showed that the maximum concentrations both appeared in the upper mixed layer, whereas, the concentration of CH₄ increased with depth and reached the maximum at the bottom. Significant correlations were observed between DMS, DMSPp and Chl-a, positive correlations between DMSPd, DMSPp and CH₄ were also found (P<0.05). DMSP degradation experiments showed that higher initial concentration of DMSP in seawater, the higher production rate of DMS was. The average air-sea fluxes of DMS and CH₄ were estimated to be (2.73±3.18) and (8.14±7.68) μmol/(m²·d) during this investigation, suggesting that the Yellow Sea and Bohai Sea acted as an important source for atmospheric DMS and CH₄ in winter.

The aims of this study were to explore the effect of long-term fertilization on the abundance of the key denitrifiers in paddy soil profiles (0~40cm), and the core factors driving denitrifiers. Soils with non-fertilization (CK), inorganic fertilizer (NPK) and organic fertilizer (ST) were collected in Ning xiang County, Hunan Province, and real-time fluorescent quantitative PCR technology was used to analyze the abundance of narG-, nirK-and nirS-containing communities in paddy soil profile (0~10cm, 10~20cm, 20~30cm, 30~40cm) and their relationship with soil properties. The results showed that compared with CK, SOC、TN、NO₃^--N、NH₄⁺-N and Olsen-P in soil profile under NPK and ST increased by 2.2%~83.6%、3.5%~58.3%、70.8%~222.1%、0.9%~83.7% and 16.5%~94.5% respectively, and pH decreased by 0.31~0.67 units. Long-term application of inorganic fertilizer and organic fertilizer increased narG, nirK, and nirS gene abundance by 0.75~7.18 times, 1.57~3.02 times, and 0.53~3.81 times, respectively. And the effect of organic fertilizer on the abundance of denitrifiers was more significant than that of inorganic fertilizer application; The abundance of narG-, nirK-and nirS-containing communities decreased gradually with soil depth increasing, which presented an obvious vertical distribution; RDA analysis showed that soil nutrients such as SOC and TN were the core factors affecting the vertical distribution of narG-, nirK-and nirS-containing populations in paddy soil, especially in the cultivated horizon, while pH was the core driving factor regulating the distribution of denitrifying bacteria in paddy field subsoil. The results can provide theoretical basis for improving soil fertility and reducing nitrogen loss and greenhouse gas emission in paddy soils.

The fungus M5-1capable of hydrolyzing phytate was isolated from the sediments of a uranium tailings repository in Guangdong Province. Its colony morphology, ITS sequences, suitable growth pH value, tolerance against uranium and effect on hydrolysis of phytate were systematically studied. The variations of pH value, orthophosphate concentration, uranium concentration and removal efficiency of uranium were monitored. The main elements and mineral components of the biomineralization products were also analyzed. It was found that the strain M5-1was Aspergillus tubingensis (MH978623) with optimal growth at pH 6~7, and with high tolerance against uranium (~0.84mmol/L). After biomineralization of U(VI)-PO₄^3- promoted by Aspergillus tubingensis mediated phytate hydrolysis for 62days, the removal efficiency of uranium reached 95.2%. SEM-EDS and XRD analyses indicated that the insoluble chernikovite and metanatroautunite were formed during the biomineralization of U(VI)-PO₄^3-. The results showed that Aspergillus tubingensis could effectively hydrolyze phytate to release soluble orthophosphate, which promoted the mineralization of U(VI)-PO₄^3-. These results provided an experimental basis for the in-situ bioremediation of uranium contaminated surface water by biomineralization of U(VI)-PO₄^3- promoted by Aspergillus tubingensis mediated phytate hydrolysis.

Using surface soils collected from Guyuan Ecological Experiment Station in Semi-arid Region restored by biochar for 4years as research objects, th effects of two types of biochar (locust tree bark biochar、sawdust biochar) at three different mass percentages (1%、3% and 5%) on soil bacterial community diversities and structures were investigated by using Miseq high-throughput sequencing technology. The results showed that the diversity of soil bacterial community was increased with biochar addition, and the diversities were higher in the treatment with sawdust biochar than that in the treatment with locust tree bark biochar. Further, 3% sawdust biochar addition had the best effect on bacterial community diversities, and its Shannon index was 6.22. The dominant taxa at phyla level were Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria and Saccharibacteria, with relative abundance of 76.80%~85.31%. The dominant taxa at class level were Actinobacteria, Alphaproteobacteria, Acidobacteria, with relative abundance of 48.13%~57.08%. At genus level, the relative abundance of the Bacillus, Nitrospira increased, while the relative abundance of the Pedomicrobium, Rhizobium decreased after biochar treatmetns. Hierarchical clustering and redundancy analysis (RDA) indicated that the application of biochar greatly affected the bacteria community structures. The microbial biomass carbon, water content, ammonium nitrogen (NH₄⁺-N), organic carbon contents had great influences on the variations of bacterial community structure. The heatmap of the correlation between taxa of dominant bacteria and environmental factors further indicated that NH₄⁺-N concentration was significantly correlated with Actinobacteria and Chloroflexi. Therefore, the change in NH₄⁺-N concentration caused by biochar addition was the key factor leading to the variations of soil bacterial communities.

Environmentally persistent free radicals (EPFRs) are a class of pollutants with emerging concern. They are detected in various environmental media, such as combustion products, soil/sediment, and natural organic matter, and have been attracted a great deal of research interest because of their potential toxic impacts to organisms. In this paper, the detection of EPFRs in ambient media was firstly been summarized. The negative effect or toxicity mediated of EPFRs was been described, including pulmonary injuries, cardiovascular disorders, neurotoxicities and biomacromolecule damages (such as protein, enzyme, and DNA). The mechanisms of these adverse effects (inducing oxidative stress, inflammatory and immune response and metabolic disorder) of EPFRs were discussed. We also discussed the urgently needed future research direction on EPFRs. This paper aims to provide reference for the potential risk assessment, health assessment and policy formulation of EPFRs in the environment.

This study investigated the association between elder dwellers' blood pressure and indoor environment conditions including dwellings' thermal and humid environment (temperature, relative humidity), chemical pollution (CO₂, CO, formaldehyde and TVOC), physical pollution (PM_2.5) and biological pollution (adherent fungi) during a heating season in Dalian, China. The results showed that the heating type was the main factor causing the difference of indoor thermal comfort between urban and rural dwellings. In rural Dalian, the large temperature step-changes between outdoor and indoor in toilets made the risk of cardiovascular disease higher for elder dwellers' than that for urban elder dwellers. The mean blood pressure of urban elderly was lower than that of rural areas with smaller variation. There was a significant correlation between indoor temperature and humidity in urban dwellings and elder dwellers' blood pressure (P<0.01). The influence of indoor temperature and humidity on blood pressure in rural area was less obvious than that in urban area. In addition, no significant correlation was found between indoor air quality parameters and blood pressure.

To understand the pollution status and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in Yinchuan, a total of 17surface sediment samples were collected from lakes and urban rivers in Yinchuan City from April to May 2018. Gas chromatography-mass spectrometry (GC-MS) was used to detect the content of PAHs. The results showed that the total content of 16PAHs in sediment of lakes and urban rivers in Yinchuan City ranged between 767.35 and 3961.53ng/g with an average of 2129.86ng/g. Compared with the pollution status of PAHs in sediments at home and abroad, the pollution status of PAHs in Yinchuan was at a high level. Source analysis showed that the main source of PAHs in sediments in Yinchuan City were incomplete combustion of petroleum and coal. The method of effects range low (ERL) and effects range median (ERM) were used to evaluate the ecological risk of PAHs in sediments. The result showed the content of Phe in surface sediments of some sampling points exceed ERM. Sediment Quality Standards (SQSs) showed the contents of Nap and Ace were between the possible effect level (PEL) and the frequent effect level (FEL), and the content of Phe was higher than FEL. Risk quotient analysis showed that the risk quotient (RQ)of Acy, Ace, Phe, and Fla were higher than 1.0. The pollution of PAHs in sample sediments may cause ecological risks.

Accurate evaluation of the pollution magnitude in a water body is an important premise for effective water pollution prevention and control. This study used Monte Carlo simulation method together with comprehensive water quality index (CWQI) method and statistical analysis of measured water quality parameters to assess water quality. The Wen-Rui Tang River watershed was used as the study site. Through the combined model and water quality data from 14 monitoring sites at Wen-Rui Tang River during 2004 to 2010, the probability of each site for every pollution level and the influence of each water quality parameter on water pollution were quantified. The results of Monte Carlo-CWQI coupled model indicated that the water quality of Wen-Rui Tang River was highly impaired. The probabilities of the water impairments at sites of Qinfen, Jiushan, Dongshuichang, Shizihe, Nanbaixiang, Huiqiao, Xinqiao, Mishaiqiao, Xianmen, Guangming, Guoxi, Quxi, Xi-ao, and Wutian being at the heavy pollution level were 28.50%, 0.55%, 92.71%, 59.73%, 78.85%, 39.38%, 78.87%, 83.09%, 65.32%, 78.08%, 0.00%, 0.96%, 68.09%, and 86.06%, respectively. The probabilities of the water impairments at these monitoring sites being worse than heavy pollution level were 71.28%, 0.01%, 4.33%, 39.76%, 21.07%, 60.59%, 4.42%, 12.41%, 11.02%, 21.24%, 0.00%, 0.02%, 1.42%, and 13.12%, respectively. The spearman rank correlation coefficient for total nitrogen (TN), ammonium-nitrogen (NH₃-N) and dissolved oxygen (DO) respectively ranged from 0.41 to 0.76, 0.25 to 0.63 and 0.14 to 0.66, which were more than twice on the values for other parameters. This result implied that TN, NH₃-N and DO were the dominant factors affecting the rate of reaching water quality standard in Wen-Rui Tang River. This investigation can broaden the viewpoints for researches and managers on river water quality evaluation and can provide abundant information for decision-making on water environment management.

The inductively coupled plasma-optical emission spectrometer (ICP-OES) was used to determine the concentrations of vanadium in surface and columnar sediments from Jianhu Lake. The modified BCR sequential extraction method was used to extract the different fractions of vanadium, and then the characteristics of spatial distribution and ecological risks of vanadium were assessed, the effects of sediment particle size on the concentrations of vanadium and its fractions were also studied. The results showed that the sediment particles in surface and columnar sediments in Jianhu Lake were mainly composed of silt and fine sand, and the concentrations of vanadium in fine particles were higher. The concentration of vanadium in surface sediments from Jianhu Lake was (117.82±63.31)mg/kg, and its horizontal distribution varied substantially. The concentrations of vanadium in exchangeable, reducible, oxidizable, and residual fraction were (8.91±8.91), (18.36±10.53), (7.67±7.67), (80.22±58.71) mg/kg, respectively. This indicated that vanadium mainly presented in the form of residual fraction. Furthermore, the clay and silt in sediments had a great influence on the reducible and residual fractions of vanadium. The vertical distribution of vanadium also varied greatly, and the concentration of vanadium in bottom sediments was higher than that in surface layer. In addition, the concentrations of vanadium were affected by clay and silt in some areas of Jianhu Lake. The degree of vanadium pollution was mild in sediments from Jianhu Lake, and the potential ecological risks of vanadium were low in most areas. The contamination levels and the potential ecological risks of vanadium in the bottom sediments were higher than those in surface layer.

The total contents of nine heavy metals (As、Cd、Cr、Cu、Hg、Ni、Pb、Sb、Zn)in sediments from Xiang River were analyzed. Geoaccumulation index (I_geo) was used to analyze the trend of pollution since 1982. The degrees of heavy metals pollution and potential aquatic organism risk were evaluated by using enrichment factor (EF) and logarithm regression models, respectively. Possible pollution source of heavy metals were deduced according to the results of principal component analysis (PCA). The results showed that the spatial distribution of these heavy metals in sediments in Xiang River were highly heterogeneous. In general, the I_geo of most heavy metals from whole Xiang River had increased slowly in the past 30 years with the exception that it decreased in the Changsha-Zhuzhou-Xiangtan section and Hengyang section. In Xiang River, the most polluted heavy metal was Cd, followed by As and Hg. ChenZhou was the most polluted area and its pollution could be characterized as the combined pollution dominated by Cd. There were two possible pollution sources of heavy metals in sediments. One source was the discharge of industrial wastewater including selecting and smelting wastewater, as well as the leakage of tailings ponds. The other source was the chemical weathering of rocks and river transportation.