Adsorption of Pb, Cd to Fe, Mn oxides in natural freshwater surface coatings developed in different seasons

Metal oxides( Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role n the fate and transport of trace metal in aquatic environments. Seasonal variation of Fe, Mn oxides and organic materials in surface oatings, which were developed periodically on glass slides in Nanhu Lake, Jilin Province, China over the time frame of three seasons,was investigated in order to understand the influence of metal oxides on Pb and Cd adsorption to heterogeneous surface coating materials(biofilm). Pb and Cd adsorption was measured under controlled laboratory conditions( mineral salts solution with defined speciation, ionic trength 0.05 mol/L, 25~C and pH 6.0). The classical Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb nd Cd adsorption to the surface coatings. In general, components in the surface coatings varied greatly with seasons altering and btained higher concentrations in summer while the content of iron oxides always exceeded that of manganese oxides. Correlation nalyses between the maximum adsorption of Pb and Cd and components in the surface coatings developed periodically indicated that Pb hase association with Mn oxides and Cd phase association with Fe oxides as well as Mn oxides were statistically significant. Effect of Mn xides on Cd adsorption was confirmed in view of its higher content in the surface coatings. The importance of ferromanganese oxides for b and Cd adsorption to the natural surface coatings developed in different seasons was evidenced.     

Persistent organochlorine residues in sediments of the Haihe River and Dagu Drainage River in Tianjin, China

Persistent organochlorine compounds were analyzed by means of GC-ECD in surface sediment samples from two selected rivers in Tianjin, Haihe River and Dagu Drainage River. A total of 16 surface sediment sites were selected along the both rivers. The frequency of detection of T-HCH and T-DDT in sediment samples both was up to 100%, which illustrated that the contamination of HCH and DDT was widespread in Haihe and Dagu Drainage Rivers. Results indicated that the concentrations of various pesticides in sediments from Haihe River were in the range of 3.30-75.96 ng/g dw for T-HCH and 1.57-211.57 ng/g dw for T-DDT. Compared with Haihe River, Dagu Drainage River was contaminated by HCHs and DDTs along the all locations and the values of T-HCH and T-DDT residues in sediments ranged from 2.30 to 124.61 ng/g dw and from 11.28 to 237.30 ng/g dw, respectively, The possible pollution sources were analyzed through monitoring results of organochlorine pesticides（OCPs） residues in sediments from the two rivers. The investigation also indicated that HCH was still used as pesticide in Tianjin partial area.     

东部平原地区湖泊富营养化的演变及区域分析

从区域的角度系统分析了东部平原地区主要湖泊富营养化的现状，重点湖泊富营养化的演变过程（列举东湖、淀山湖、巢湖和太湖），阐述东部平原地区湖泊富营养化的形态及区域特征，并对富营养化区域政策及产业作了分析，最后有针对性地提出了湖泊富营养化防治的区域对策和建议，为寻求生物治理湖泊富营养化提供有效途径。     

我国城市降雨径流污染控制模式探讨

随着城市的发展与点源污染控制的不断完善,城市降雨径流污染日益突出,对城市水体构成严重威胁,必须得到有效的控制。对国内外城市降雨径流污染控制模式进行了比较,并结合我国的实际情况,首次提出了双重控制模式,以期为我国城市降雨径流污染的控制与决策提供参考和借鉴。     

膜生物反应器中膜的最佳反冲洗周期

将解吸分为平衡解吸和完全解吸两种类型，对水环境中含油泥沙上油分子的解吸特性进行了研究，通过试验，分析了解吸平衡时的吸附等温线及平衡解吸量随清水解吸液用量变化的规律，同时也对含油泥沙发生完全解吸时的最大解吸量和极限残留量进行了研究，并得出了它们随泥沙粒径变化的规律。     

Investigation on Fe, Mn, Zn, Cu, Pb and Cd fractions in the natural surface coating samples and surficial sediments in the Songhua River, China

Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals （Fe, Mn, Zn, Cu, Pb, and Cd） using the modified sequential extraction procedure （MSEP）. The results show that the differences between NSCSs and SSs in Fe fi＇actions were insignificant and Fe was dominantly present as residual phase （76.22% for NSCSs and 80.88% for SSs） and Fe-oxides phase （20.33% for NSCSs and 16.15% for SSs）. Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase （48.27%） and that in SSs present as residual phase （45.44%）. Zn, Cu, Pb and Cd were found dominantly in residual fractions （〉48%）, and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter （OM）, and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.     

巢湖底泥磷的释放模拟实验研究

在实验室条件下，模拟了DO控制、pH值调节、温度调节、水动力条件等，进行了底泥释磷实验。实验表明：（1）厌氧条件下，底泥中的磷向水体释放，且释放强度随pH值的升高而升高。好氧条件下，底泥非但没有向水体释放磷，反而从水体中吸附磷，呈“负释放”状态；且pH值越低，“负释放强度”越大。（2）温度升高有利于底泥中磷的释放，最大释放强度随温度的升高而提前。（3）搅动条件下的底泥磷释放量大于静置条件下的底泥磷释放量。（4）微生物对磷释放有明显的影响。从本次模拟实验结果看，体系温度升高、减少溶解氧、提高pH以及施以水动力作用，均可使底泥中的磷释放量增加，在常温（25℃）、厌氧、pH=7.5条件下，底泥中磷向水体的释放量将增加17％左右。     

滇池草海污染底泥疏挖及处置工程效益分析

草海污染底泥疏挖及处置工程是滇池综合治理的重要组成部分。本文针对草海底泥分布及污染特征。在已确定的工程措施基础上，探讨分析了工程的综合效益。明确了该工程是解决滇池内源污染的重要措施，工程的实施能有效清除草游淤泥、改善水质及促进水生生态恢复，可望达到积极而显著的环境效益，同时也将取得良好的社会效益和经济效益。     

水体沉积积物重金属生物有效性及评价方法

在研究以重金属为主要污染的水本中，通常把沉积物视为探索环境重金属污染的工具。由于沉积物重金属化学为和生态效应的复杂性，对沉积物中重金属生物有效性的研究是当前学术界的热点研究课题。本文就沉积物中重金属的生物有效性及沉积物质量评价方法作了简要评述。包括沉积物对水生生物的作用机理，孔隙水重金属浓度的估算沉积物质量评价方法，沉积物质基准。     

浦阳江（浦江段）水体污染问题及其防治对策分析

自改革开放以来,我县处于社会高速发展,工业化的进程越来越快,相对应的城市化也达到了前所未有的水平.在城市高速发展的背景下,居民对环境问题的重视度越来越高,同时也是工业和社会的发展与环境的矛盾越来越突出.环境问题中与居民息息相关的是城市的水污染问题,工业化的发展使污水处理的力度不达标,同时也对居民的生活生产造成了影响.本文从浦阳江（浦江段）水体污染的原因和基本现状出发,对浦阳江（浦江段）水体污染问题进行了深入的研究和探讨,以便引起相关的部门加以重视,制定具体的相应的合理的法律法规.