The effect of limiting nutrient on metal toxicity to selenastrum capricornutum

Metal toxicity on selenastrum capricornutum were examined by batch culture and chemostat culture system. EC₅₀ values under nutrient‐limited condition and saturated condition were compared. The two EC_5Os differed by a factor of 10.6 for Cd in batch test, and differed by a factor of 6.5 in continuous test. Both batch and continuous test results indicate that inhibition on algal growth is more severe under nutrient‐limited conditions compared to that under near saturation conditions.

Strong correlation, as characterized by the correlation coefficient ρ, were found between the activation level (nutrient requirement) and the tolerance of microorganisms to the toxicant. ρ is equal to 0.9 for the case of Cd in batch test and 0.6 in continuous test. The theory in this study provides generally good estimations to the dose‐response relationship at limiting nutrient conditions. The study indicate that nutrient conditions constitute an important factor in algal toxicity tests.     

Microbial Potential for the Anaerobic Transformation of Simple Homocyclic and Heterocyclic Compounds in Sediments of the Tsengwen River

The ability of microbial populations to mediate the anaerobic transformation of four aromatic compounds (aniline, benzoic acid, pyridine, and quinoline) in sediments of the Tsengwen River was examined. Along the river, from a freshwater (0.0° salinity) to an oceanic (37.0° salinity) environment, five sampling stations were chosen to collect the sediment. Sediment slurries were incubated in an anaerobic mineral salts medium that was amended with multiple electron acceptors, including manganese (IV) and ferric (III) oxides, and the concentrations of the aromatic substrates were followed over a 3- to 4-month period. Most sediment samples showed a complete loss of benzoic acid and quinoline (0.12–0.21 mM) within approximately three months. Pyridine was transformed after a lag period of 53 days in the sediment slurries from the freshwater environment which had been amended with both metal oxide (either Fe (OH)₃ or MnO₂) and inhibitor (either BESA or molybdate). Pyridine was not transformed in other sediment slurries. No significant metabolism of aniline was apparent in any of the sediments.     

Decomposition of perfluorooctanoic acid by microwaveactivated persulfate: Effects of temperature, pH, and chloride ions

Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S₂O ₈ ^2? ) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH = 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01?C0.15 mol·L^?1), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol·L^?1 at 90°C and 0.06 mol·L^?1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature.     

Fate of polycyclic aromatic hydrocarbons during vitrification of incinerator ash in a coke bed furnace

Fate of polycyclic aromatic hydrocarbons (PAHs) during the vitrification of fly ash and bottom ash from the municipal waste incinerator in a coke bed furnace was investigated. In this system, both coke and lime were added to enhance the melting reaction. The major PAH sources in this system were ash and coke, which respectively contributed 97% and 3% of PAHs in the input-mass. During vitrification process, low molecular PAHs (LM-PAH, 2-3-ring), median molecular PAHs (MM-PAH, 4-ring) and high molecular PAHs (HM-PAH, 5-7-ring) mass respectively accounted for >99%, >99% and 84% of the output-mass emitted as the stack flue gas; while those discharged from the slag were <1%, <1% and 16%, respectively. The O/I (output-mass/input-mass) ratio of LM-, MM- and HM-PAHs were 0.063, 0.002 and <0.001, respectively. The high distribution in flue gas and O/I ratio of LM-PAHs is reasonable since they are more easily evaporated, hence difficult to be removed by air pollution control devices. On the contrary, the HM-PAHs, having lower vapor pressure, primarily stays mainly in slag. Based on the 21 total PAH content in feeding ash and slag, the reduction efficiency of the coke bed furnace was >99.9%. To minimize the risk of secondary pollution, the efficiency of coke bed furnace should be improved to reduce the PAH emission into ambient air.     

基于蒙特卡洛模拟与PMF模型的黄河流域沉积物重金属污染评价及源解析

沉积物是河流的重要组成部分,而沉积物中重金属的富集严重威胁着水环境安全.黄河流域沿程分布着众多工业城市,且流域水土流失量大,泥沙携带重金属进入河流导致沉积物重金属污染问题日趋严重,研究黄河流域沉积物中重金属污染状况对流域生态安全具有重要意义.收集2000~2020年发表的关于黄河流域沉积物中重金属（铅、镉、铬、砷、锌、铜、镍和汞）含量的数据,首先基于描述性统计及地统计法分析重金属的空间分布特征,进一步采用蒙特卡洛法进行地累积指数（I_geo）、潜在生态风险及毒性单位概率的评价,最后结合正定矩阵因子分解模型（PMF）与Pearson相关性分析确定污染源个数及贡献率.结果发现,黄河流域沉积物中ω（Pb）、ω（As）、ω（Zn）、ω（Ni）、ω（Cu）、ω（Hg）、ω（Cr）和ω（Cd）的均值分别为26.92、11.78、87.17、31.13、24.96、0.07、73.36和0.58 mg·kg^-1,分别超过黄河流域各省土壤背景值均值1.27、1.08、1.26、1.05、1.09、2.32、1.14和5.95倍,其中Cd超标倍数最大,应当引起重视;I_geo：Cd>Hg>Cr>Cu>Pb>Zn>As>Ni,Cd和Hg存在中度-严重污染;数据表明黄河流域上、中和下游沉积物重度生态风险占比分别为18.6%、15.7%和7.1%,呈递减趋势;黄河流域沉积物中重金属处于低毒性状态;溯源分析表明黄河流域沉积物重金属的4个来源分别是矿业源（42.2%）、自然活动（38.3%）、农业活动（11.6%）和电镀废水（7.9%）.研究结果可为黄河流域制定相关污染防控措施提供依据.     

风暴潮风险研究进展

中国沿海是全球少数几个风暴潮风险最大的区域之一。受全球气候变暖和海平面上升的影响,沿海地区风暴潮灾害风险水平呈显著上升的趋势。从灾害风险理论出发,在对风暴潮风险的认识、风暴潮危险性评估、风暴潮易损性评估,以及风暴潮综合风险评估等四个方面,系统地总结了目前风暴潮风险研究的最新成果、研究进展和存在的主要问题。总体来看,现阶段风暴潮风险评估研究还比较薄弱,未来的风暴潮风险研究应该由单要素评估走向综合评估,加强风暴潮风险评估的综合性和系统性。随着沿海地区社会经济的发展,应充分考虑全球变化和海平面上升对未来风暴潮风险的影响,完善风暴潮综合风险评估体系,提升风暴潮预报预警能力,为风暴潮灾害的防灾减灾工作提供科学依据。     

Biodegradation of coplanar polychlorinated biphenyls by anaerobic microorganisms from estuarine sediments.

In this study, we investigated the biodegradability of biphenyl and 5 congeners (one non-planar and four coplanar) of polychlorinated biphenyl (PCB). Biphenyl, the non-planar congener 2,3',4',5-tetrachlorobiphenyl (25-34 CB), and the four coplanar congeners 3,3',4,4'-tetrachlorobiphenyl (34-34 CB), 3,4,4',5-tetrachlorobiphenyl (345-4 CB), 3,3',4,4',5-pentachlorobiphenyl (345-34 CB), and 3,3',4,4',5,5'-hexachlorobiphenyl (345-345 CB) were amended at a concentration of 10 mg/L into anoxic sediment slurries collected from the estuaries of the Tansui River and the Erjen River. During 2 years' incubation under sulfidogenic conditions, biphenyl was persistent, while all other chlorinated congeners, except for 345-345 CB, were dechlorinated with or without a lag period in sediment slurries collected from both rivers. Dechlorination of coplanar and non-planar congeners began with para chlorine removal. All para chlorines from the mono-, di-, and trichlorobiphenyl groups could be removed by sediment slurries from both rivers. Microbial communities in sediment from the Erjen River additionally fostered meta-dechlorination activity, but only after removal of all the para chlorines. Addition of Tween 20 (0.05%, v/v) into sediment slurries from the Tansui River did not enhance dechlorination rates or extents, but the addition of toluene- or 3-chlorobenzoate-adapted sediments enhanced dechlorination of 34-34 CB and 345-4 CB.     

Synergistic effects of combination of photolysis and ozonation on destruction of chlorophenols in water.

Synergistic effects including TOC elimination, ozone consumption and microtoxicity reduction for combination of photolysis and ozonation compared to those of direct photolysis and ozonation alone on destruction of chlorophenols including 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol were studied. It was found that the synergistic effects of combination of photolysis and ozonation increased obviously with increasing initial pH of solution to basic pH levels. Results showed that the synergistic effects of photolytic ozonation under the conditions imposed was notable with mineralization rate enlarging more than 100%, oxidation index (OI) decreasing 50%, and microtoxicity being reduced by 30%, indicating that the potentialities of photolytic ozonation compared to direct photolysis and ozonation alone was remarkable for treatment of industrial wastewater containing chlorophenols.     

Na型粉末树脂回收废水中低浓度氨氮

为探究Na型粉末树脂回收废水中低浓度氨氮的可行性,分别采用静态摇瓶与动态树脂柱方法进行实验研究。结果表明:预处理仅使粉末树脂吸附氨氮的能力降低了5%;在中性与酸性条件下,Na型粉末树脂对低浓度氨氮去除率均可达到99%;每增加2 g·L~(-1)树脂投加量,氨氮去除率会提高20%,但吸附容量下降2.85 mg·g~(-1);钙镁离子的存在会降低Na型粉末树脂对氨氮的吸附容量,最大降低量为3.5 mg·g~(-1);由于钾离子与氨氮为同价离子,其影响不显著。Na型粉末树脂对氨氮的吸附符合Langmuir吸附等温线,吸附过程符合准二级动力学。根据实验结果,Na型粉末树脂静态运行方式适用于低浓度氨氮的回收,但动态运行方式下粉末树脂达到吸附饱和时间更短,因此,需要对运行方式进一步研究。