Lead contamination in tea garden soils and factors affecting its bioavailability

The consumption of heavy metals is detrimental to human health and most countries restrict the concentration of metals such as lead (Pb) in food and beverages. Recent tests have detected high Pb concentrations in certain commercial brands of tea leaves and this finding has raised concerns for both producers and consumers. To investigate what factors may be contributing to the increase in Pb accumulation in the tea leaves we collected tea leaves and soils from tea producing areas and analyzed them for Pb concentration, pH and organic matter content. The result showed the Pb concentration of 47% investigated tea leaves samples was beyond 2 mg kg(-1), the permissible levels given by China. The total Pb concentration in the surface and subsurface soil layers averaged 36.4 and 32.2 mg kg(-1), respectively which fall below of the 60 mg kg(-1) limit provided for organic tea gardens in China. The pH of the tea garden soils was severely acidic with the lowest pH of 3.37. Soils under older tea gardens tended to have a lower pH and a higher Pb bioavailability which was defined as the amount of lead extracted by CaCl2 solution than those under younger tea gardens. We found that the concentration of bioavailable Pb and the percentage of bioavailable Pb (bioavailable Pb relative to total Pb concentration) were positively correlated with soil H+ activity and soil organic matter content, and the organic matter accumulation contribute more effects on Pb bioavailability in these two factors. We conclude that soil acidification and organic matter accumulation could contribute to increasing Pb bioavailability in soil and that these could increase Pb uptake and accumulation in the tea leaves.     

纳米Fe3O4的制备及其对对硝基甲苯的催化降解

采用共沉淀法制备了纳米四氧化三铁（Fe3O4），并进行必要表征，制备所得的Fe3O4粒径与商品Fe3O4相当，均为15～20nm。在中性、碱性条件下，制备的材料表面带负电，而在弱酸性条件下，则带正电。制备出的Fe3O4与商品的Fe3O4一样，对对硝基甲苯具有相同的机械催化降解效率，均符合准一级反应动力学。     

全氟辛烷磺化物及其环境问题

全氟辛烷磺化物(PFOS)是全氟化合物(PFCS)的代表物,以PFOS为原料可以生产许多用途广泛的PFOS相关物质,并且在环境中都能降解生成PFOS.PFOS是一种新型的持久性有机污染物(POPs),已经成为环境科学研究的热点问题.主要从物理化学性质、毒性、环境及人体暴露水平等方面对PFOS进行了综述,并将中国有关的现有数据与其他国家进行了比较.研究表明,中国人体、水体均存在着大范围的以PFOS为主的PFCS污染.     

Persistent organochlorines in human breast milk collected from primiparae in Dalian and Shenyang, China

The present study determined the concentrations of organochlorines (OCs) such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and tris(4-chlorophenyl)methane (TCPMe) in human breast milk collected from primiparae in Dalian and Shenyang, northeastern China during 2002. In addition, dioxins and related compounds in pooled samples of human breast milk from Dalian and Shenyang were also analyzed. OCs were detected in all the human breast milk samples analyzed in this study. The predominant contaminants in human breast milk were HCHs, DDTs and HCB, and the levels were relatively higher than those in other countries. On the other hand, concentrations of dioxins and related compounds, PCBs, and CHLs were relatively low. Concentrations of OCs in human breast milk from Dalian, which is located along the coast of Bo Hai Strait, were significantly higher than those from Shenyang, implying that the residents in Dalian might be mainly exposed to these contaminants from seafood. When the relationship between concentrations of OCs in human breast milk and age of primiparae was examined, no significant correlation was observed. This might be caused by the limited sample numbers and narrow range of mother's age and/or recent ban of DDT and HCH production and use. Significant correlation between concentrations of TCPMe and DDTs in human breast milk suggested that technical DDT might be a source of TCPMe in the Chinese population. When daily intakes of DDTs and HCHs to infants through human breast milk were estimated, human breast milk from Dalian showed significantly higher contribution than Shenyang, implying that infants in Dalian might be at higher risk by these contaminants.     

超声波有机改性凹凸棒土的苯酚吸附性能研究

采用超声波技术,对凹凸棒土进行有机改性,提高凹凸棒土的苯酚吸附能力,比较了不同的阳离子表面活性剂的改性效果,并且通过正交实验得出了超声波改性的最优化工艺条件为：十八烷基三甲基氯化铵的添加比例为35 mmol/100 g,超声波处理时间10 min,屏极电流0.5 A.在此条件下,苯酚去除率可达酸处理凹凸棒土的80倍以上,是搅拌有机改性的1.5倍.     

环境评估机构市场化运行发展趋势展望

在对评估工作的过去和现状进行回顾的基础上，对评估工作的市场化和拓展评估领域进行了分析和展望，以使评估工作发挥更大的作用，更好地为环境管理工作服务。     

Development and verification of a screening model for surface spreading of petroleum

Overflows and leakage from aboveground storage tanks and pipelines carrying crude oil and petroleum products occur frequently. The spilled hydrocarbons pose environmental threats by contaminating the surrounding soil and the underlying ground water. Predicting the fate and transport of these chemicals is required for environmental risk assessment and for remedial measure design. The present paper discusses the formulation and application of the Oil Surface Flow Screening Model (OILSFSM) for predicting the surface flow of oil by taking into account infiltration and evaporation. Surface flow is simulated using a semi-analytical model based on the lubrication theory approximation of viscous flow. Infiltration is simulated using a version of the Green and Ampt infiltration model, which is modified to account for oil properties. Evaporation of volatile compounds is simulated using a compositional model that accounts for the changes in the fraction of each compound in the spilled oil. The coupling between surface flow, infiltration and evaporation is achieved by incorporating the infiltration and evaporation fluxes into the global continuity equation of the spilled oil. The model was verified against numerical models for infiltration and analytical models for surface flow. The verification study demonstrates the applicability of the model.     

低温等离子体技术处理挥发性有机物

介绍了低温等离子体技术在处理挥发性有机物(VOCs)的研究现状和成果;探讨了低温等离子体技术的发展趋势.     

环评中人群健康评价的指标探讨

在环境污染对人群健康的影响评价中，为了选择的指标能够确切地反映污染与效应之间的关系，比较系统地总结和研究了各项指标的适用范围、敏感性、可操作性及应用实例，阐述了环境污染对人体的非特异性危害的原理及其指标应用。提出５方面共１０项指标作为评价的常用指标。     

白腐菌处理染料废水的研究进展

白腐菌是一种可有效处理染料废水的丝状真菌 ,它可通过其分泌的特殊的降解酶系或其他机制将各种人工合成的染料彻底降解为CO2 和H2 O ,同时 ,对脱色具有良好的作用。本文就白腐菌的生物学特性及其对染料的降解酶系、机理和白腐菌发酵的主要影响因子、白腐菌处理染料废水的有关研究及应用现状进行了综述