Acta Academiae Medicinae Sinicae

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CHINA ENVIRONMENTAL SCIENCECE

CHINA ENVIRONMENTAL SCIENCECE

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	2014 Vol.34 Issue.2,Published 2014-02-20

	273	Advances in HONO sources, HONO simulations, and the impacts of the HONO sources on regional or global air quality
		AN Jun-Ling, LI Ying, TANG Yu-Jia, CHEN Yong, QU Yu
		HONO sources (i.e., HONO emissions, homogeneous gas-phase production and heterogeneous reaction production), HONO simulations, and the impacts of the HONO sources on regional or global air quality were reviewed. Reaction of photoexcited NO2 with water vapor contributed much to HONO formation in elevated NOx emission areas but the accurate reaction rate needs to be quantified. Heterogeneous formation of HONO on wet surfaces could be the key source of HONO, which was supported by air quality model simulations. The photosensitized NO2 reduction on soot is possibly a large contributor to HONO concentrations in high soot emission areas but the related field studies are required. Observations of HONO emissions from soil are very limited and urgently needed.
		2014 Vol. 34 (2): 273-281 [Abstract] ( 511 ) [HTML 1KB] [ PDF 362KB] ( 3174 )

	282	Characteristics and formation mechanism of a serious haze event in January 2013 in Beijing
		YANG Xin, CHEN Yi-Zhen, LIU Hou-Feng, ZHAO Yu-Xi, GAO Jian, CHAI Fa-He, MENG Fan
		A serious haze process from 10th to 16th in January 2013 of Beijing was analyzed. During the period of haze, aerosol vertical distribution was retrieved from the MPL-4B-IDS series lidar system with Fernald algorithm. In order to illustrate the formation mechanism of this pollution episode, the surface aerosol measurement at the same site was compared with the lidar result. It was found that during the observation period, haze occurred in 89.4% of the time, among which 39.8% were recognized as heavy haze episodes. The extinction coefficients strongly correlated with surface ρ (PM2.5 ) (r=0.95). During the study, the average PBL height was only 293m, when 91% of the time it was less than 500m and restrained the effective diffusion of pollutants significantly. Extinction coefficient of each vertical height reached more than 1.5km-1above the ground. By comparing the analysis of the aerosol depolarization ratio, it was found that the atmospheric extinction above the city was caused by the combined effect of particulate aerosols and atmospheric moisture. The aerosol optical depth (AOD) at 532nm in this severe haze event was high and affected by the relative humidity greatly. In lower RH, the value of AOD was contributed by particulate aerosols, and atmospheric moisture made a significant contribution due to the hygroscopicity of fine particle when the RH was high. Additionally, stability of the PBL situation and pollutants emitted from regional area were the main reasons of this severe haze event, and high humidity made the haze more worse.
		2014 Vol. 34 (2): 282-288 [Abstract] ( 525 ) [HTML 1KB] [ PDF 921KB] ( 1730 )

	289	Influences of weather on PGEs accumulation in road dust
		LIU Yu-Yan, LIU Hao-Feng, ZENG He-Hua, ZHANG Lan
		In order to study the characteristics and its mechanism of PGEs acculation in road dusts from different types weather, Changji city was elccted as an example, and samples of road dust were collected and determined by ICP-MS after aqua regia digestion. The results showed that runoff souring and wind strength were the primary external forces, which affected PGEs transport and transfer, while the rainfall and temperature primarily affected the formation of runoff in urban city, poor rainfall in arid area was more beneficial for accumulation of PGEs. Influences of various weather situations on PGEs content in road dust were as follows: the PGEs content increased after small rainfall (12hours rainfall5mm); but always decreased after snowfall, no matter how big, when the temperature was lower than 0℃. After single small rain, single moderate and bigger rain(12hours rainfall>5mm), and continuous small rain, the PGEs contents increased, decreased, and increased respectively, however, when the accumulation achieved top limit, there was no increasing but slow and steady decreasing tendency in continuous small rain. After a wind force 4, the PGEs content decreased significantly.
		2014 Vol. 34 (2): 289-294 [Abstract] ( 283 ) [HTML 1KB] [ PDF 324KB] ( 795 )

	295	Anthropogenic heat emissions in the Yangtze River Delta region
		LU Yan, WANG Qin-Geng, DI Yi-Ran, SONG Yuan-Yuan, ZHANG Yan-Yan, SUN Ping
		Based on conventional statistical data on energy consumption, transportation, population, anthropogenic heat emissions from the urban agglomeration of the Yangtze River Delta (YRD) in 2010 were estimated by using the top-down energy inventory method. Results show that total amount of anthropogenic heat emissions was 1.4′1019J/a. Industry, transportation, buildings and human metabolism contributed 75.1%、12.5%、9.9% and 2.5%, respectively. Emissions from Shanghai, Suzhou, Wuxi, Hangzhou and Nanjing accounted for nearly 71% of the total amount. The mean flux in study area was 5.3W/m2with high values between 20 and 70W/m2 in most urban areas. The flux in Shanghai was obviously higher than in other cities. In order to be applied in environmental and climate modeling, a gridded inventory with simple profiles of temporal variations was provided.
		2014 Vol. 34 (2): 295-301 [Abstract] ( 389 ) [HTML 1KB] [ PDF 2039KB] ( 1032 )

	302	A modeling study of a dust event using WRF-Dust Model
		MA Jing-Hui, ZHOU Guang-Qiang, ZHOU Ji, ZHOU Wei-Dong, CHEN Min, CAO Yu
		A fully coupled atmospheric chemistry model, weather research and forecasting (WRF) with dust component (WRF-Dust) was applied to investigate a dust event occurring over Shanghai and surrounding regions during May 1-4, 2011. Through the comparisons with observations, the model was able to capture main features of the event fairlywell. Overall, the simulations showed good agreement with the observations for the starting time (~11:00on May 1), the ending time (~02:00on May 2), and dust peak values of the event around Shanghai. However, some simulation biases were found for several meteorological factors and dust concentrations over several sub-regions during the event. In addition, the model did not reproduce dust backflow over the coastal regions of the Yangtze River Delta. Finally, the possible reasons causing the simulation biases were discussed and methods to improve simulations of dust events were proposed.
		2014 Vol. 34 (2): 302-310 [Abstract] ( 349 ) [HTML 1KB] [ PDF 2771KB] ( 1046 )

	311	Characterization of water-soluble ion species of aerosol in Nanjing, China
		ZHANG Qiu-Chen, ZHU Bin, GONG Dian-Li
		Aerosol samples were collected in 2010~2011at urban and suburban sites of Nanjing. Meanwhile the major water-soluble ions of aerosol were determined by ion chromatography (IC) method. The results show that during the sampling period, the aerosol pollution of Nanjing at both sites were more serious in spring, autumn and winter except in summer. The size distribution of aerosol showed two peaks in 0.65~2.1 μm and 5.8~9 μm at both sites. The mass concentration of PM2.5 had great impact on the visibility. The total mass concentration of water-soluble inorganic ions in aerosol was higher in spring and winter compared with that in summer and autumn. The total mass concentration of anions was significantly higher than the cations in the whole year, which were especialy distinct in the fine particles. The proportion of water-soluble inorganic ions in aerosol was higher at urban site than that at suburban site in summer, autumn and winter. The ratio of NO3-/SO42- was lower than 1at two sites, which reflected that the stable sources (such as coal combustion) was a major source of atmospheric pollutants. The ratio of NO3-/SO42- had obvious seasonal variations, the lowest of which was in summer and the highest was in winter. NH4+, K+, NO3-and SO42- were mainly enriched in the fine particles; Na+, Cl-and NO2- were enriched both in fine and coarse particles; Ca2+, Mg2+ and F- were mainly enriched in the coarse particles. The results of factor analysis (FA) showed that there were 3main sources of aerosol.
		2014 Vol. 34 (2): 311-316 [Abstract] ( 389 ) [HTML 1KB] [ PDF 493KB] ( 1173 )

	317	Phylogenetic diversity of bacteria areasols in precipitation of Beijing Area
		LIANG Zong-Min, DU Rui, DU Peng-Rui, WANG Ya-Ling, LI Zi-Ming
		Atmosphere bioaerosols was always closely linked with the health of human beings and flora and fauna, however, recent studies suggested that the bio-aerosols may impact the environment and climate change directly by acting as cloud condensation nuclei (CCN) and/or ice nucleation (IN). Unfortunately, there was still little knowledge about the composition of microbial community of the biological ice nucleis in the precipitation, especially, in China mainland. At present study, the precipitation samplers were taken from the Beijing city area. The sampling was carried out in different months in 2011 and 2012. The bacterial diversity was analyzed using the 16S rRNA gene sequencing based approaches. Seven clone libraries were established resulting from the different rain-water sampling months. The results indicated that Proteobacteria (75.6%~100%) were dominant in the precipitation including Alphaproteobacteria, Betaproteobacteria,and Gammaproteobacteria. While other bacterial communities such as Bacteroidetes, Actinobacteria, Deinococcus-Thermus, Cyanobacteria, Nitrospira and Firmicutes were involved as well. Furthermore, a small proportion of undetermined bacteria (TM7, 1.2%~7.2%) were also found. In addition, microbial diversity in the snow water samplers was obviously much more than that in the rain-water samplers, which suggested that some biological ice nuclei may present and influence in the formation of precipitation. Moreover, results showed that Pseudomonas, in which some strains with high effective ice nucleation activity, was also found in the samplers. Therefore, further concerns should be done for the climatic effect of these microbes.
		2014 Vol. 34 (2): 317-323 [Abstract] ( 325 ) [HTML 1KB] [ PDF 390KB] ( 809 )

	324	Simultaneous desulfurization and denitrification by O2+, O3
		BAI Min-Di, MAO Shou-Lei, ZHU Yu-Peng, LI Chao-Qun
		In order to solve the disadvantage of high investment and operating costs, and large occupied area in conventional technology of simultaneous flue gas desulfurization and denitrification, reactive oxygen species (O2+ and O3) produced by a strong ionization dielectric barrier discharge were injected into the emission duct. In the plasma reaction duct, O2+ and O3 oxidized NO to HNO3, and SO2 to H2SO4. The principle for O2+ and O3 produced was discussed. The mechanisms for ·OH radical generated from O2+ reacting with H2O, and simultaneous flue gas desulfurization and denitrification by ·OH radicals were introduced. The composition of the recovered acid liquid was analyzed. Removal rates of 97.4% for NO, and 83.2 % for SO2 were obtained under the following optimal experimental conditions: the molar ratio of reactive oxygen species (O2+, O3) to SO2 and NO was five; the inlet flue gas temperature was 65 °C; the H2O volume fraction was 10%, and the reaction time was 1s.
		2014 Vol. 34 (2): 324-330 [Abstract] ( 311 ) [HTML 1KB] [ PDF 505KB] ( 943 )

	331	Tertiary nitrogen removal of the municipal secondary effluent using PHAs as solid carbon sources
		LI Peng, TANG Lei, ZUO Jian-E, YUAN Lin, LI Zai-Xing
		Polyhydroxyalkanoates (PHAs) pellets, which were taken from a denitrification biofilter with sustained-release carbon source materials, were used to investigate the effects of microbes and nitrate on the organic carbon release rate of PHAs and the effects of temperature, pH and NO3--N concentration on the denitrification rates. The results indicated that the total organic carbon (TOC) release rates of original PHAs and those with biofilm attached were determined to be 0.030 and 0.053mg/(g·d) in the deionized water, respectively, which were much lower than that of 0.533mg/(g·d) in simultaneous presence of microbes and nitrate (30mg/L of NO3--N concentration). The effects of temperature and pH on denitrification rates were significant. When influent NO3--N concentration was 50mg/L, the maximum denitrification rates achieved to 0.067mg/(g·h) at 30℃ in the temperature range of 15 to 35℃, and to 0.061mg/(g·h) at pH7.8 in the pH range of 6.0 to 9.0. The relationship between denitrification rates and NO3--N concentrations appeared to be in good agreement with Monod Equation, and the maximum denitrification rate and the saturation constant were 4.74mgNO3--N/(gSS·h) and 56.6mg/L, respectively.
		2014 Vol. 34 (2): 331-336 [Abstract] ( 307 ) [HTML 1KB] [ PDF 625KB] ( 1161 )

	337	Decolorization of dye wastewater with spongy-iron induction-heating fixed bed reactor (IHFB)
		WANG Ming, LI Jian-Chao, MAO Yong, LI Qing, XU Na, JIN Jing, ZHENG Wei
		For the heterogeneous reactions of organic-pollutants in wastewater, a novel reactor, the induction-heating fixed bed reactor (IHFB) realizes the targeted energy transfers on the micro-interface of catalyst particles. Due to the high temperature on the solid-liquid phase interface deriving from the ferromagnetic heating, the degradation of aqueous organic pollutants was significantly promoted with the lower energy consumption. The decolorization experiments showed that the decolorization percentage could reach 93.5% after running 30minutes in the optimal reaction conditions, i.e. influent pH 6~7and 30℃, HRT of 2.08min. The UV-vis absorption peak of direct blending purple (D-BL) at 554nm disappeared after Ni-SI react with D-BL. SEM-EDS revealed the formation of iron oxide and iron hydroxides on the surface of Ni-SI after degradation of direct blending purple (D-BL) after D-BL reaction. A degradation mechanism of direct blending purple (D-BL) was proposed. First, molecular was adsorded on the surface of modified sponge iron, then the iron nanoparticles react with water to produce hydrogen radical by the Ni catalysis and local high temperature, finally the hydrogen radical destroied the most toxic conjugated double bond and benzene ring in D-BL molecular. In addition, in the optimal operation conditions, the decolorization percentages of the acid black (10B), the direct red (D-GLN) and the real dye wastewater reached 82%, 78% and 81% respectively. The study revealed that IHBF had a tremendous application potential in dye wastewater treatment.
		2014 Vol. 34 (2): 337-344 [Abstract] ( 266 ) [HTML 1KB] [ PDF 803KB] ( 1058 )

	345	Effect of aeration intensity on the process of sludge predation by worms
		ZHANG Xiao-Qi, TIAN Yu, WANG Qiang
		Sludge reduction can be achieved through the predation by oligochaeta worm-Limnodrilus sp.. To analyze the effect of aeration intensity on the process of sludge predation, changes in worm activity, sludge properties and sludge reduction efficiency under different intensities of aeration were investigated. The results showed that these worms had limited tolerance to aeration intensity. The number of injured worms increased with the increasing aeration intensity and retention time in sludge, and fewer injured individuals (1.7% of the total)was found under the mild intermittent aeration. The lactate dehydrogenate activity of worms was higher under the aeration intensity of 2.8~9.5m3/(m2·h), which may imply the higher level of material metabolism and energetic consumption of the worms at those aeration conditions. Less nitrate accumulation was found in the supernatant of sludge during the predation under the lower aeration intensity, and the increase in sludge volume index (SVI) caused by lack of dissolved oxygen was restrained by the worms, showing their performance for improving sludge settling. The sludge reduction of worms for the intermittent aeration of 2.8m3/(m2·h) was more stable than those for continuous aerations.
		2014 Vol. 34 (2): 345-351 [Abstract] ( 258 ) [HTML 1KB] [ PDF 518KB] ( 726 )

	352	Effect of temperature gradient on algal inhibition by in-situ water-lifting aeration in a stratified reservoir
		SUN Xin, YE Li-Li, ZHAO Wei-Li, HUANG Ting-Lin, CONG Hai-Bing
		Based on the method of computational fluid mechanics, flow velocity and algae concentration outside the water-lifting aerator were numerically modeled, the simulation results were compared against the field data. Under water depth of 80m, when the temperature gradient increased from 0.17℃/m increased to 0.73℃/m, the radius of core zone for algae control increased from 100m to 150m,ratio of the algae control zone to the whole flow domain slightly increased from 25.16% to 28.60%, the time required for complete mixing of algae increased from 16d to 24d. The residence time of algae under the compensation point was longer than 48h for each simulation case, but it was not sensitive to the temperature gradient, the algal growth was effectively inhibited. Simulated profiles of water temperature and algae concentration agreed well with the measured ones. The proper spacial distance between two water-lifting aerators could be determined as 250m.
		2014 Vol. 34 (2): 352-358 [Abstract] ( 313 ) [HTML 1KB] [ PDF 832KB] ( 830 )

	359	Effect of raw water quality on formation of nitrification in water distribution pipes
		ZHANG Da, YANG Yan-Ling, LI Xing, XIANG Kun, LIU Yang-Yang, XU Mei-Ling, HUANG Liu, CHEN Nan
		Effect of raw water quality on nitrification formation and its influence on effluent in water distribution pipes were studied by pipeline reactors simulated the water situation. Water samples were prepared in laboratory to simulate ClassⅡ, Class Ⅲ and Class Ⅴof the surface water standard. The results showed that the concentration of ammonia nitrogen (NH4+-N) and dissolved oxygen (DO) in raw water had significant effect on NH4+-N removal. Under sufficient DO, removal rate of NH4+-N improved with the increasing NH4+-N concentration in raw water. When DO was insufficient, NH4+-N removal was limited by DO. Accumulation of nitrite nitrogen (NO2--N) was significantly affected by concentration of NH4+-N in raw water at initial stage of biofilm formation. NO2--N accumulated more serious with higher NH4+-N content, but the influence gradually weakened as the biofilm matured. The quantity of AOB was considerably affected by concentration of NH4+-N in raw water, and AOB quantity increased with the concentration of NH4+-N. The quantity of NOB was considerably affected by the concentration of both NH4+-N and DO in raw water. Low DO concentration would inhibit activity of NOB, resulted in fewer quantity of NOB and less accumulation of NO2--N. Nitrification in water distribution pipes was generated by nitrifying bacteria in the bulk water and biofilm, but biofilm nitrify bacteria had a higher level than bulk nitrify bacteria.
		2014 Vol. 34 (2): 359-363 [Abstract] ( 249 ) [HTML 1KB] [ PDF 360KB] ( 579 )

	364	Influences of environmental factors on the photodegradation of tylosin by goethite
		GUO Xue-Tao, YANG Chen, ZENG Xiao-Ming, DANG Zhi, HU Yun
		In order to understand the photochemical process of antibiotics in aquatic environment and evaluate their ecological risk accurately, the influences of tylosin initial concentration, pH, ionic strength, and humic acid on the photodegradation of tylosin by goethite were investigated. The results showed that the photodegradation rate of tylosin was proportional to solution pH and inversely proportional to tylosin initial concentration and ionic strength. The humic acid could promote the photodegradation of tylosin on goethite. The photodegradation of tylosin on goethite might include the homogeneous reaction in the solution and the heterogeneous reaction at goethite surface.
		2014 Vol. 34 (2): 364-370 [Abstract] ( 318 ) [HTML 1KB] [ PDF 624KB] ( 693 )

	371	Inhibition mechanisms of apparent nitrification rate in membrane bio-reactor with salinity
		LI Bin, WANG Zhi-Wei, AN Ying, WU Zhi-Chao
		To explore inhibition mechanism of apparent nitrification rate in membrane bio-reactor (MBR) under salinity, nitrification of the activated sludge in MBR under different salinity was simulated by batch experiments. The apparent nitrification rate, the autotrophic bacteria activity and the amount of deoxyribonucleic acid (DNA) and protein in both SMP and EPS were determined. The results showed that as the salinity increased, the apparent nitrification rate gradually decreased. When the salinity was over 12.5g/L, NH4+-N content in the system increased. Also, the autotrophic bacteria activity was gradually inhibited, and the inhibition level was positively correlated with the salinity. Meanwhile, the amount of DNA in SMP and EPS increased when the salinity was over 2.5g/L, indicating that the inhibition of sludge activity was resulted from the destroying of cell structure. The amount of protein in SMP and EPS significantly raised as the salinity increased, showing that the release of NH4+-N due to the protein hydrolyzed in the sludge system was also the reason for the decline of the apparent nitrification rate. With salinity under 12.5g/L, the influence of NH4+-N releasing on apparent nitrification rate decline was increased with the increase of salinity.
		2014 Vol. 34 (2): 371-377 [Abstract] ( 313 ) [HTML 1KB] [ PDF 439KB] ( 901 )

	378	Effects of COD/P ratio on contaminant removal and N2O emission during simultaneous nitrification and denitrification process
		WANG Rong, CHENG Peng-Fei, ZHANG Jian, JIA Wen-Lin, XIE Hui-Jun, YAN Yu-Jie
		Two parallel anaerobic-aerobic SBRs were conducted to evaluate the impacts of different COD/P ratio on contaminant removal and nitrous oxide (N2O) emission during simultaneous nitrification and denitrification (SND) process. The results showed that the removal efficiencies of COD and ammonium were more than 90% in both SBRs. TP and TN removal was enhanced simultaneously with the decrease of COD/P ratio. It was mainly caused by the enrichment of polyphosphate accumulating organisms (PAOs) at low COD/P ratio. Part of PAOs could use nitrate/nitrite as electron acceptors to take up the phosphorus. N2O emission was reduced with the decrease of COD/P ratio. The N2O emission amount per cycle at low COD/P ratio was only 76% of that at high ratio. It was due to the decrease of N2O yield by heterotrophic denitrification.
		2014 Vol. 34 (2): 378-382 [Abstract] ( 319 ) [HTML 1KB] [ PDF 364KB] ( 712 )

	383	Cultivate of granular sludge based on denitrifying phosphate accumulating bacteria
		HE Li, GAO Da-Wen
		Aerobic granules based on denitrifying phosphate accumulating bacteria were developed in sequencing batch reactors (SBRs) with flocs sludge as seed to improve nitrogen and phosphorus removal rate. The results showed that the denitrifying phosphate accumulating bacteria was successfully cultivated after 45days. During the synthetic domestic wastewater treatment, the phosphate removal rate of this system was around 90%, and the both removal rates of COD and ammonia nitrogen were around 95%. Meanwhile, the unit amount of nitrate denitrifying phosphate uptake reached 0.876mg/mg, and the ratio of denitrifying phosphate accumulating bacteria was 74.36% in phosphorus-accumulating bacterias (PAOs). The highest volume percentage of the granules was in the range of 1.0~2.0mm, and the settling velocity of mature granules in reactor was 44~72m/h. It can be concluded that aerobic granules based on denitrifying phosphate accumulating bacteria can be cultivated by adjusting the dissolved oxygen of SBR.
		2014 Vol. 34 (2): 383-389 [Abstract] ( 285 ) [HTML 1KB] [ PDF 521KB] ( 1098 )

	390	Adsorption of dye on calcinate product of the waste Mg(OH)2/AC composite
		SUN Jin-Xiang, WANG Hai-Zeng
		The optimum conditions of the preparation of MgO/AC from the high temperature calcination of Mg (OH)2/AC which was a waste from dyeing wastewater was studied. The MgO/AC product was characterized by the thermogravimetry- differential thermal analysis (TG-DTA), brunaner-emmett-teller (BET), and X-ray diffraction (XRD). The adsorption ability of weak acid brilliant blue RAWL on fresh MgO/AC and after regeneration was tested. It was showed that Pseudo-second-order model and Langmuir model fitted the adsorption of the RAWL on MgO/AC at 293 ~ 313K. After 4times of regeneration, the adsorption capacity of MgO/AC was 1.08 times higher than the fresh MgO/AC, and 2.11times higher than the fresh Mg (OH)2/AC.
		2014 Vol. 34 (2): 390-395 [Abstract] ( 241 ) [HTML 1KB] [ PDF 465KB] ( 703 )

	396	Improved nitritation performance by selective sludge discharge in aerobic granular sludge process
		LIU Wen-Ru, YIN Fang-Fang, DING Ling-Ling, GAO Ling-Hui, WANG Jian-Fang, SHEN Yao-Liang
		An aerobic granular sludge reactor was run for 160 days to study the effectiveness of selective sludge discharge as a control strategy to improve the long-term stability of nitritation process. The reactor operation could be divided into three phases. During phase one the solid retention time (SRT, was extremely high) was controlled by sludge washed-out spontaneously with effluent withdrawal, leading to granules disaggregated and nitritation performance deteriorated. Sludge was selectively removed from the top of the settled sludge bed to control SRT which resulted in an increased specific NO2--N accumulation rate from 7.44 to 8.08mg/(g·h) in phase two [SRT=(45±5) d], and then reached as high as 9.14mg/(g·h) in phase three [SRT=(30±5)d]. On the contrary, the specific NO3--N production rate decreased from 3.01mg/(g·h) to 1.54mg/(g·h) when SRT was (30±5) days. The ratio of nitrite accumulation in effluent reached above 80% during phase three. All these results demonstrated that controlling SRT by selectively biomass discharge was an effective strategy to improve the long-term stability of nitritation process. Additionally, analysis suggest that using reactor with large height-diameter ratio and introducing competitors with nitrite oxidizing bacteria (NOB) for nitrite can both improve the implementation of selective sludge discharge-control strategy for nitritation.
		2014 Vol. 34 (2): 396-402 [Abstract] ( 354 ) [HTML 1KB] [ PDF 694KB] ( 925 )

	403	Removal of microcystin-LR by a microcystin-degrading strain immobilized by activated carbon fiber
		YUAN Yuan, WU Juan, LI Yu-Cheng, WANG Ning
		Distribution of MC-LR during the extraction of phycocyanin was studied. A microcystin-degrading strain was immobilized by activated carbon fiber (ACF), and the effect factors, such as the pretreatment methods of activated carbon fiber, dosage of activated carbon fiber, pH value, temperature and the initial concentration of MC-LR were investigated. The results showed that 81.2% of MC-LR existed in the ultrafiltrate during the phycocyanin extraction. The immobilized strain presented significantly better performance in MC-LR removal than the non-immobilized strain. The performance of ACF which was pretreated with (1+9) HCl was much better than others. The optimum removal conditions were as follows: dosage of activated carbon fiber was 10g/L, the temperature was 35℃, the pH value was 8.0, and the initial concentration of MC-LR was 13.6mg/L. Therefore, immobilized strain showed a certain tolerance towards the pH value and the temperature. And MC-LR could be removed effectively in the range of pH5 to pH9, 10℃~35℃.
		2014 Vol. 34 (2): 403-409 [Abstract] ( 369 ) [HTML 1KB] [ PDF 618KB] ( 716 )

	410	Uncertainty and sensitivity analysis of input conditions in large shallow lake hydrodynamic model
		LI Yi-Ping, QIU Li, TANG Chun-Yan, BU Min-Sheng, TIAN Wei, YU Zhong-Bo, Kumud Acharya
		Uncertainty and sensitivity analysis of four important input conditions on the Environmental Hydrodynamic Fluid Code (EFDC) model results (i.e., water level, water age and currents) was investigated for a large shallow lake, Lake Taihu, China. The four input conditions included three boundary conditions (i.e., inflow/outflow, wind speed, wind direction) and an initial condition (i.e., initial water level). The Latin Hypercube sampling (LHS) as a global sensitivity method was used to estimate the uncertainty and sensitivity from the four input conditions. The results showed that uncertainties in the hydrodynamic process existed due to the uncertainties of model input conditions. Among the four input conditions, the initial water level was the most sensitive factor for the simulated water level and water age with the uncertainty contributions of 85.73% and 66.125% respectively, while it had barely 3% contributions to vertical averaged velocity. Wind speed played a significant role in the uncertainty of the velocity in the surface layer with a sensitivity coefficient of 58.70%, while it only had 5.25% and 3.00% contributions to the simulated water level and water age, respectively. Additionally, there was a similar impact of the four input conditions on the uncertainty of velocities in different layers. The four input conditions’ contributions to the velocities were as follows: wind speed (55%~60%) > wind direction (10%~15%) > initial water level ≈ inflow/outflow (1%~5%). Thus, the results provided reliable information for the model prediction of large shallow lakes like Lake Taihu. For different output targets, improving the precision of the input conditions with priority can efficiently enhance the precision of the hydrodynamic model.
		2014 Vol. 34 (2): 410-416 [Abstract] ( 391 ) [HTML 1KB] [ PDF 595KB] ( 1159 )

	417	Spatio-temporal evolution of groundwater pollution in the urban areas of Jilin City
		WEI Run-Chu, XIAO Chang-Lai, LIANG Xiu-Juan
		Projection pursuit method was adopted to establish groundwater pollution index model. Correspondingly, groundwater pollution indexes of monitoring wells from 1980 to 2009 were calculated. Considering the non-continuity of groundwater pollution between the both sides of Songhua River, modified local polynomial was used to complete interpolation of pollution indexes sub-regionally. Then distribution maps of groundwater pollution indexes from 1980 to 2009 showed. The results showed that, groundwater was contaminated in all districts with different severities for region-widely high groundwater pollution indexes, especially in Jiangbei district. The groundwater pollution in all districts revealed a ight-severe-light character in the time revolution. Spatio-temporal evolution of groundwater pollution in this region was closely linked with human activities. From the analysis of the contributions of all pollution factors to groundwater pollution indexes in each year, a conclusion could be drawed that, nitrite, nitrate and ammonia were the main factors affecting the groundwater environment, while nitrite was the dominant one with a contribution rate of 0.7 up and down in most years.
		2014 Vol. 34 (2): 417-423 [Abstract] ( 342 ) [HTML 1KB] [ PDF 924KB] ( 1131 )

	424	Cultivation of demulsifying bacteria Alcaligenes sp. S-XJ-1 using ultrasonic pretreated excess sludge
		HUANG Xiang-Feng, ZHU Qi-Wei, SHEN Chang-Ming, WANG Shen, LU Li-Jun, LIU Jia
		In order to find a new way of excess sludge utilization, sludge extract was used in the biosynthesis of demusifier by Alcaligenes sp. S-XJ-1. It was practical to cultivate highly efficient demulsifying strains in sludge extract. Sludge extract was obtained by the untrasound condition of 443~56647kJ/kg TS. In sludge culture medium, maximun concentration of ammonia nitrogen, organic nitrogen and phosphorus were 171.94,142.20 and 76.29mg/L. Sludge extract contained metallic elements such as K, Ca, Mg, Fe that were essential to the synthesis of S-XJ-1. After 7days cultivation, the biomass of S-XJ-1in sludge extract was 0.3%~68.3% higher than that in MMSM. Highest yield (2.03g/L) was obtained when specific energy was 56647KJ/kg TS. pH buffering capacity and concentration of organic nitrogen might have a great impact on the yield. The bio-demusifier produced with sludge extract had a quite stable demusifying ration of 80%, of which the CSH and C/N did not show much difference to that with MMSM.
		2014 Vol. 34 (2): 424-430 [Abstract] ( 324 ) [HTML 1KB] [ PDF 461KB] ( 861 )

	431	Inactivation of Cryptosporidium parvum in drinking water by ultrasonic irradiation
		HU Jian-Long, RAN Zhi-Lin, LI Shao-Feng, ZHANG Chao-Sheng
		Ultrasonic on inactivation of Cryptosporidium parvum was studied under different operational parameters, such as ultrasonic frequency, ultrasonic power, pH and temperature. The mechanism of inactivation of Cryptosporidium parvum was preliminary discussed by morphological observation, and inactivating kinetic analysis was also focused. The results indicated that low frequency favored the inactivation of Cryptosporidium parvum, 92.5% of inactivating rate could be achieved under the condition of 19.8kHz ultrasonic (15min), pH 7.2and temperature 20±1℃, while the inactivating rate decreased if the frequency increased. Furthermore, the inactivating rates were almost the same regardless of ultrasonic power was 103W or 151W, and the value of pH had slight effect on inactivating. The inactivating rate was 95.6% using ultrasonic treatment for 15min at 36℃ while 88.3% at 9℃, which indicated higher temperature was conducive to the inactivation of Cryptosporidium parvum. Ultrasonic cavitation caused cell membrane damage and cytoplasm outflow in inactivating Cryptosporidium parvum. Ultrasonic inactivation of Cryptosporidium parvum was in line with pseudo-first-order kinetics, and lower frequency and higher power lead to better ultrasonic cavitation. Therefore, it was suggested that the intensity of ultrasonic cavitation was the main factor for inactivating Cryptosporidium parvum.
		2014 Vol. 34 (2): 431-436 [Abstract] ( 279 ) [HTML 1KB] [ PDF 620KB] ( 721 )

	437	Effects of two combined amendments on heavy metal bioaccumulation in paddy soil
		ZHOU Hang, ZHOU Xin, ZENG Min, LIU Li, YANG Wen-Tao, WANG Ying-Jie, LIAO Bai-Han
		Stabilization of heavy metals in situ was investigated. Two combined amendments (LS, limestone + sepiolite; HZ, hydroxyhistidine + zeolite) were applied to paddy soil with multi-metal (Pb, Cd, Cu, and Zn) contamination at ratios of 0.2%, 0.4%, and 0.8% (w/w). The effects of these two combined amendments on heavy metal bioavailability in soil, and on uptake and accumulation of heavy metals in rice plants were investigated. The experiment results indicated that application of LS and HZ significantly increased soil pH values and cation exchange capacity contents, while the organic matter contents did not change obviously. Higher soil pH values and CEC contents were observed with LS treatment soils than HZ. Application LS and HZ resulted in a reduction in toxicity characteristic leaching procedure (TCLP) extract metal contents of amended soils. Compared with the control soil, contents of Pb, Cd, Cu, and Zn in TCLP extracts were decreased by 25.7%~52.2%, 12.7%~25.7%, 6.4%~17.2%, and 8.6%~23.4%, respectively, as a result of 0.2% to 0.8% addition of LS and decreased by 57.6%~80.1%, 7.0%~40.9%, 2.3%~22.7%, and 4.5%~33.2%, respectively, as a result of 0.2% to 0.8% addition of HZ. LS and HZ significantly decreased the bioavailability of Pb, Cd, Cu, and Zn in the paddy soils, and inhibited the bioaccumulation of heavy metals in rice organs, resulting in decreasing the concentrations of Pb, Cd, and Cu of rice roots, shoots, husks, and brown rice. Significant positive linear correlations were found between heavy metal concentrations in TCLP extracts and those in rice tissues (roots and brown rice) except for Zn. Extracting heavy metals with TCLP was a suitable method for estimating heavy metal bioavailability concentrations of amended soil.
		2014 Vol. 34 (2): 437-444 [Abstract] ( 325 ) [HTML 1KB] [ PDF 467KB] ( 1145 )

	445	Major soil factors affecting ecological threshold for copper and the predictable models
		WANG Xiao-Qing, LI Ju-Mei, WEI Dong-Pu, CHEN Shi-Bao, MA Yi-Bing, HUANG Zhan-Bin
		The hazardous concentrations (HCp) are the concentrations of a substance in soils which can be toxic to p% of bio-species in ecosystems and, in other words, protect (1-p)% of bio-species in ecosystem. The values of HCp are the scientific basis for setting up soil ecological quality standards. In the present study, the values of HCp for copper in soil were derived using a method of species sensitivity distribution based on copper toxicity data from Chinese soils. Correcting the derived HCp with aging factor (AF) to obtain soil ecological thresholds of copper, i e., aged HCp. Predictable models for copper ecological thresholds based on soil properties were also developed. The results showed that soil pH and cation exchange capacity were the main soil factors affecting soil ecological thresholds of copper. Soil cation exchange capacity and pH could explain the >80% variation of it. The two-factor predictable models based on soil pH and cation exchange capacity could predict copper ecological thresholds with determination coefficients (R2) from 0.820 to 0.913. While the three-factor predictable models with taking into account the effect of organic carbon on copper ecological threshold were more accurate than the two-factor models with R2 from 0.852 to 0.988. The predictable models developed in the present study proved the quantitative relationship between soil properties with copper ecological thresholds and the necessity of developing and implementing soil specific or regional soil environmental quality standards.
		2014 Vol. 34 (2): 445-451 [Abstract] ( 360 ) [HTML 1KB] [ PDF 429KB] ( 1640 )

	452	Effects of city buildings on content and distribution of polycyclic aromatic hydrocarbons in adjacent soil
		YU Ying-Peng, YANG Yi, LIU Min, LU Min, ZHENG Xin, WANG Xin, WANG Rui-Qi, LIU Ying, WANG Qing
		Sixteen priority control polycyclic aromatic hydrocarbons (PAHs) were analyzed in twenty surface soil samples collected from the plinth or aproll edges of the building (B) and 5-meter sites away from the building (B-5), to discuss the impacts of urban buildings on the level and distribution of PAHs from the surrounding soil. The results showed that the concentration of PAHs ranged from 824 to 8960 ng/g in soil at B, with an average of 2649ng/g, PAHs in B-5 varied from 673 PAHs in to 1706ng/g with an average of 1297ng/g which were significantly lower than that of site B. The distribution profile of PAHs was mainly dominated by 4~5ring PAHs in the study area. Fl, Pyr, InP and BghiP in soil were dominant species both at B and B-5and accounted for 48% and 45% of total mass PAHs, respectively. HJ-5, AJ, AJ-5, EB-5and TC-5were in the moderate degree of pollution(600~1000ng/g), and the others were categorized heavily polluted (>1000ng/g) by reference to Maliszewska-Kordybach soil standard. Soil TOC exhibited the trend of enrichment at B relative to at B-5, and there was no clear correlation with PAHs. BaA, Chry, B(b+k)F, BaP, InP, and DahA were major contributor to TEQBaP concentration. The source apportionment showed that soil PAHs at B and B-5are mainly originated from coal, gasoline and diesel combustion, and PAHs at B-5might be partly from oil spill.
		2014 Vol. 34 (2): 452-458 [Abstract] ( 334 ) [HTML 1KB] [ PDF 972KB] ( 933 )

	459	Spectral characteristics of dissolved organic matter in co-composting process of municipal sludge with biochar.
		YAN Jin-Long, JIANG Tao, ZHAO Xiu-Lan, WEI Shi-Qiang, WANG Ding-Yong, LI Lu-Lu, GUO Nian, SUN Wen-Bin
		Changes in the UV-visible and fluorescence characteristics of DOM from the co-composting process of municipal sludge with two types of biochars were discussed. The results showed the aromaticity and humification of DOM from the co-composting with biochars significantly increased compared with control, which indicated in favor of improving the maturity of compost. The treatment with biochar from peanut shell showed the highest maturity, followed by wheat straw biochar. After 21days, compost treated with biochar from peanut shell reached its maximum maturity, while that treated with biochar from wheat straw continued to increase over the whole time. Meanwhile, the DOM from the compost with or without treatment was found to be autochthonous, FI>0.7, BIX>0.8, mainly attributed to the microbial decomposition of compost. Thus, the spectral characteristics of DOM are capable of assessing the degree of maturity of compost during the co-composting process with biochars from different source.
		2014 Vol. 34 (2): 459-465 [Abstract] ( 521 ) [HTML 1KB] [ PDF 988KB] ( 10931 )

	466	Migration behavior of Pb and its vaporization control during sewage sludge incineration process
		LIU Jing-Yong, SUN Shui-Yu, CHEN Tao, LU Shao-You, WANG Yu-Jie, XIE Wu-Ming, DU Qing-Ping, YANG Zuo-Yi, LI Lei
		Staged incineration was carried out on laboratory-scale tube furnace for the sewage sludge incineration treatment. Partitioning, transformation and removal of Pb were investigated under different combustion conditions and four solid sorbents including CaO, Al2O3, fly ash and kaolin were added in sewage sludge incineration process in order to reduce the Pb emissions effectively. The calculation of thermodynamics equilibrium was conducted to identify the Pb removal simultaneously. Thermodynamic equilibrium calculation results indicated that Pb mainly volatilized as the form of PbO (g) during sludge incineration process. PbCl2 (g) was the main volatile substance in the presence of Cl compounds which can promote Pb volatilization. PbSO4 (s) generated while sulfide compounds existed, which would inhibit the volatilization of Pb during incineration. Stable compounds including (PbO)(Al2O3)(s), PbSiO3(s) and CaPbO4(s) were formed and the temperature of PbO(g) formation was delayed by adding the sorbents Al2O3, SiO2 and CaO. Al2O3 was more efficient for removal of Pb than SiO2 and CaO. The results of incineration experiments showed that the residue of Pb in incineration bottom ash had a decreasing trend with increasing incineration temperature and the proportion of reducible Pb fraction increased in the bottom ash, while that of residual fraction showed a descending trend. The increasing incineration time had little influence on the volatilization of Pb, but the proportion of Pb residual fraction decreased in thebottom ash. Pb would change from chloride states to the oxidation states as a result of the increasing moisture, which inhibited the volatilization of Pb chloride. With the increasing excess air coefficient, the residual rate of Pb decreased in the bottom ash. With the increase ratio of the solid adsorbent, the residual rate of Pb increased gradually and immobilized in the bottom ash. The CaO and Al2O3 were superior to fly ash and kaolin in the controlling of Pb volatilization.
		2014 Vol. 34 (2): 466-477 [Abstract] ( 343 ) [HTML 1KB] [ PDF 1513KB] ( 1008 )

	478	Toxic effect of cadmium on Microcysis aeruginosa and Scenedesmus obliquus
		LIU Lu, YAN Hao, XIA Wen-Tong, LI Cheng, ZHANG Ting-Ting
		Toxic effect of cadmium on Microcysis aeruginosa Kutz. and Scenedesmus obliquus (Turp.) Kutz were researched by using different concentrations of Cd2+. The results showed the growth of S. obliquus was accelerated in Cd2+ concentration of 0.1mg/L, and decreased in Cd2+ concentration over 0.15mg/L. Toxicant could promote the growth at low concentration while restrain at high concentration, which might be an effect of hormesis. But M. aeruginosa was more sensitive to Cd2+ with the growth obviously inhibited when the concentrations of Cd2+ were 0.05mg/L and treat 72h, and the inhibitory effect was obvious with increasing Cd2+. The membrane permeability of the two algae changed under the stress of Cd2+, and protein and nucleic acid contents of two freshwater algae rose up. The photos of scanning electron-microscopy showed that the superficial flocs of algae increased with the rise of Cd2+ concentration, especially for M. aeruginosa. Meanwhile, contents raised and the POD and CAT activities in the two algae all increased with the rise of Cd2+ at the early stage. The two algae could absorb Cd2+, and S. obliquus had more adsorption ability than M. aeruginosa at the unit cell. The results indicated that the main toxic mechanisms of Cd2+ imposing on two algae involved the superoxide anion radical generation that induced the physiological and biochemical changes of the algae, and hurt the algae. Compared with the M. aeruginosa, S. obliquus not only had a better tolerant of Cd2+, but a better adsorption ability of Cd2+. It indicates that S. obliquus has the potential of being a biological material to deal with water Cd2+.
		2014 Vol. 34 (2): 478-484 [Abstract] ( 462 ) [HTML 1KB] [ PDF 853KB] ( 1102 )

	485	Model study on eutrophication control in Yingze Lake of Taiyuan city
		WU Chun-Fang, XU Ming-De, LI Lu, JING Sheng-Yuan
		Aiming at Yingze Lake eutrophication, based on gathering data and long-time water quality monitoring, hydromatical model and water quality model, combined with a variety of biological processes were applied to established lake eutrophication coupled model, calibrated and verified by measurement of water quality data, the total nitrogen, total phosphorus, chlorophyll-a and transparency were selected to simulate, and concluded transport diffusion and spatial and temporal distribution of nutrients. Combined with the practical situation, from replenishment methods, replenishment frequency and changing lakes flexible structure, schemes on hydrodynamic condition and numerical simulation were put forward, and the modified effects of hydromatical condition and material transport diffusion of different schemes were studied. The results showed obvious spatial and temporal distribution of chlorophyll-a concentration which was between 0.035~0.105mg/L. Phytoplankton such as algae grow quickly,which was the peak period of algal bloom and water quality deterioration．Strategies such as increasing the hydraulic circulation and improving the inflow water quality would achieve good effects in water quality management.
		2014 Vol. 34 (2): 485-491 [Abstract] ( 285 ) [HTML 1KB] [ PDF 1446KB] ( 954 )

	492	Effects of flocculation of Prorocentrum micans by modified clay on nitrogen and phosphorus
		LU Guang-Yuan, SONG Xiu-Xian, YU Zhi-Ming, CAO Xi-Hua, YUAN Yong-Quan
		Harmful algal blooms (HABs) occurred frequently in coastal water around the world over the past decades. Flocculation of algal cells by modified clay has been proven to be an effective method and was the only practical strategy applied in the field, particularly in Asia. To assess the long-term ecological effects of this method, the study investigated the variation of two major nutrients during succession of cultured dinoflagellate Prorocentrum micans Ehrenberg (P. micans, A1) flocculated with modified clay (MC,A2). More than 60% of P. micans cells were efficiently removed by 0.4g/L of MC within 3.5h, and cells were no rebooming in A2. The results indicated that MC removed 26% of TN, 42% of TP, 85% of DIP, 35% of DIN, respectively. compared with TON and TOP concentrations in A1, it has been decreased of 120μmol/L and 6μmol/L by MC on day 33, respectively. Simultaneously, the study speculated that MC treatment controlled the nutrient exchange (between water and sediment) by blocking and sealing the organic-clay matrix in the surface areas of sediments. The study would benefit the further explore of long term environmental effects of the MC application for HABs’ mitigation.
		2014 Vol. 34 (2): 492-498 [Abstract] ( 330 ) [HTML 1KB] [ PDF 519KB] ( 744 )

	499	Simulation on the variation characteristics of methylmercury of the water-level-fluctuating zone in the Three Gorges Area
		ZHANG Cheng, SONG Li, WANG Ding-Yong, SUN Rong-Guo, ZHANG Jin-Yang
		To investigate variation of methylmercury of the water-level-fluctuating zone in the Three Gorges Reservoir Area, dynamic changes of methylmercury contents and influencing factors were analyzed in soil and water by simulation experiment. The results showed that the methylmercury contents in soil initially increased but then decreased in both the flooding and drying process. Flooding could promote the transformation of inorganic mercury into organic forms. Methylmercury contents in soil increased with the number of wet-dry cycles. The average methylmercury content in soil during the second flooding phase was 22.13% higher than the first one, whereas the average methylmercury content increased by 58.17% in the second drying phase. The ratio of methylmercury to total mercury in soil during the second flooding phases was significantly higher than that during the first, and the alternate wet-dry environment was beneficial to mercury methylation. Methylmercury in soil was rapidly released into water, resulted in an obvious increase of methylmercury content in water. Methylmercury contents in water increased by 119.42% after the first flooding cycle and 334.72% after the second. The results showed that there was no correlation between methylmercury contents in water and methylmercury contents in soil. Methylmercury contents in soil were significantly affected by soil pH, organic matter content, Eh and soil moisture. Meanwhile, water pH, DO, DOM and temperature considerably influenced methylmercury contents in water.
		2014 Vol. 34 (2): 499-504 [Abstract] ( 282 ) [HTML 1KB] [ PDF 289KB] ( 808 )

	505	Nitrogen isotopic characteristics and source attribution of nitrate in different water bodies in the paddy rice system of the Taihu Lake region
		XIA Yong-Qiu, LI Yue-Fei, ZHANG Xin-Yu, LIN Jing-Hui, WANG Shu-Wei, ZHOU Wei, YAN Xiao-Yuan
		To discriminate among NO3-–N sources in different water bodies in paddy rice system, δ15N-NO3- abundance and chemical compositions (e.g., NO3-, NH4+, TP, Cl-, SO42-) were measured in water samples from pond, irrigation ditch, river, and ground water in rice system of the Taihu Lake region at three periods. It was found that nitrate was the dominant nitrogen species in most water samples. During the fertilizing period (June), the δ15N-NO3- value of water samples were lower than those collected in other months, suggesting that the surface water and groundwater receive a significant contribution of NO3-–N from agricultural fertilizer at this period. In periods prior to fertilization (April to May), the low δ15N value in pond water was attributed to rainfall, and the high δ15N value in ground water resulted mainly from denitrification. In periods after the fertilization (July to August), the high δ15N value in pond water was caused by aquaculture wastewater, and the low δ15N value in ground water indicated main nitrate source of agricultural leaching. The δ15N values varied within a narrow range in river and irrigation water during all the three periods, but their nitrate source differed. Sewage and manure contributed nitrate to river water, while rainfall mainly control the nitrate of irrigation water. We put forward new intervals of Cl- and molar ratio of NO3-/Cl- to discriminate among NO3-–N sources in Taihu Lake region.
		2014 Vol. 34 (2): 505-510 [Abstract] ( 280 ) [HTML 1KB] [ PDF 426KB] ( 984 )

	511	Responses of the antioxidant enzymes in Meretrix meretrix exposed to effluent from municipal sewage treatment plants for short-term
		SU 恩Ping, MENG Fan-Ping, SUN Ting, FU Wen-Chao, WANG Qun, LI Yong-Fu, HU Heng
		In order to investigate if effluent from municipal sewage treatment plants (STPs) cause oxidative stress in marine organisms, Meretrix meretrix were exposed to effluent from the Licunhe STP in Qingdao City at various concentrations (0%, 1%, 5%, 10% and 20% V/V), diluted in seawater, for 15days. Antioxidant enzymes analyzed in the viscera of mussels were superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR). Results showed that the variation trend of SOD activities with exposure time exhibited a parabolic curve shape with a maximal increment of 15.88%, which was induced from day 6 to day 12 in both exposure groups (10% and 20% effluent). Both CAT and GPx were inhibited by the effluent with the highest inhibition 64.38% and 52.39%, at the day 9 and day 12, respectively. At higher effluent concentration (20%), GR activity was inhibited constantly during the exposure period. However, GR activities responded in a parabolic curve shape in other exposure groups where an initial increase was observed at day 3 or day 6 followed by a significant decrease after day 9, and the highest increment were 81.47% and 80.91%, at day 3 and day 6, respectively. Current experimental results suggest that STPs do not have the capacity to biodegrade harmful chemicals sufficiently to prevent toxic action of effluent, and SOD, CAT, GPx and GR activities in viscera of M. meretrix are sensitive indicators of oxidative stress induced by effluent.
		2014 Vol. 34 (2): 511-517 [Abstract] ( 287 ) [HTML 1KB] [ PDF 421KB] ( 654 )

	518	Isolation and identification of a phenol-degrading strain and optimization for its immobilization using response surface methodology
		GE Qi-Long, YUE Xiu-Ping, WANG Guo-Ying
		A phenol-degrading strain was isolated from the activated sludge of a cokes wastewater treatment facility in Taiyuan City. Based on its physiology, biochemical characters and the analysis of its 16S rRNA gene sequence, the isolated strain named PD-07 was identified as a member of the genus Diaphorobacter. Metabolic pathway research showed that the strain could be induced to synthesize intracellular catechol-2,3-dioxygenase.To improve the phenol degradation rate, a study of embedding immobilized strain was conducted with calcium alginate as material. Firstly, factors playing important roles in the phenol degradation rate of immobilized cell were selected based on Plackett-Burman design. Then the path of steepest ascent was undertaken to approach the optimal region of the phenol degradation rate. Finally, the optimal levels of those main factors were further optimized by using Box-Behnken design and response surface analysis. Quadratic equation was adopted to fit the test data. The fitting curve had a good correlation with the measured values. The optimal conditions were as follows: alginate concentration 3.83%(m/V), calcium chloride concentration 0.3mol/L, bacteria-cement ratio 1:26.73, immobilized time 2h, rotation rate 180r/min, culture temperature 30℃, initial pH value 7.2, liquid-solid ratio 4.86:1. Under the optimal conditions mentioned above, the phenol degradation rate reached 96.89%.
		2014 Vol. 34 (2): 518-525 [Abstract] ( 351 ) [HTML 1KB] [ PDF 600KB] ( 1249 )

	526	Effects of humic acid and cysteine on the biotransformation of HgS by Shewanella oneidensis MR-1
		CHEN Yan, HUANG Xiao, SI You-Bin
		Effects of humic acid and cysteine on the biological dissolution and methylation of solid HgS by Shewanella oneidensis MR-1were studied. The results showed that the biological solubility of solid HgS was increased with the increasing humic acid concentration, and the concentration of dissolved HgS was 3.35mg/L at the humic acid concentration of 10mg/L. The biological methylation rate of HgS was rising at the humic acid concentration from 1 to 5mg/L, declining while the humic acid concentration from 5 to 10mg/L, and the highest methylation rate was about 10.55%. Cysteine added with different concentration had little influence on the biological solubility of solid HgS, but it could accelerate the methylation reaction process and increase the biological methylation rate of HgS by S. oneidensis MR-1up to 19.23%. The present study provided direct evidence for the biological dissolution and methylation of solid HgS by iron-reducing bacteria in the natural aquatic ecosystem.
		2014 Vol. 34 (2): 526-531 [Abstract] ( 367 ) [HTML 1KB] [ PDF 393KB] ( 1354 )

	532	Experience research on formaldehyde emission from wood-based panels and measurement of emission parameters
		CHI Dong, LI Li-Qing, MA Wei-Wu
		The measurements of formaldehyde emission from plywood, density board, block board and laminate flooring were obtained using a 1m3 small environment chamber at different temperatures and loading degrees. The experimental results showed that quick emission of formaldehyde occurred initially (0~3h), and then tended to decrease over time. Higher temperatures facilitated formaldehyde emission from wood-based panels, the total emission increased 10%~30% with a temperature increase of 5℃, while the formaldehyde emissions from unit volume panel decreased at higher loading degrees. The key parameters: the initial mobile concentration, Cm,0, the diffusion coefficient, Dm and the partition coefficient, K, determining formaldehyde emission from wood-based panels, were calculated by using emission process and equilibrium concentration in the closed environment chamber at a series of load degrees. The simulation results were coincident with experimental data, which indicated that the method used in the article is an effective means to study the emission rules of formaldehyde emission from wood-based panels.
		2014 Vol. 34 (2): 532-538 [Abstract] ( 268 ) [HTML 1KB] [ PDF 585KB] ( 1652 )

	539	Prediction model of noise event for single flight based on neural network ensemble
		XU Tao, YAN Xian-Jin, YANG Guo-Qing
		Through analyzing the influence factors of the noise event for single flight, the regression prediction model based on BP neural network was established. Then, the ensemble prediction model based on neural network for single noise event was constructed by selecting neural networks with the aid of adaptive genetic algorithm. Simultaneously, in order to maintain the diversity of neural networks, different number of hidden nodes and Bagging algorithm were used. Experimental results show that the proposed ensemble prediction model based on neural network was better than the model of single BP neural network in terms of generalization ability and higher stability. The average accuracy rate of the proposed model was 96.9% on the test set within ±3dB error and was 6.8% higher than that of the single network model.
		2014 Vol. 34 (2): 539-544 [Abstract] ( 319 ) [HTML 1KB] [ PDF 424KB] ( 990 )

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