各国水体沉积物重金属质量基准的差异及原因分析

对8种重金属的海洋和淡水沉积物的质量基准进行了Box-Whisker图解分析,结果表明,各国水体沉积物重金属质量基准值均在2－3个数量级范围之间变化,相差超过4－5个数量级的极大值的出现,则通常与局部区域沉积物的污染程度和实验所用测试生物的敏感性有关,同时剖析了造成基准差异性的原因,以便从总体上对我国水体沉积物质量基准的制定有所启发和借鉴。     

太湖零点行动前后水质状况对比分析

根据 1 998年 1 1月和 1 999年 1 0月的监测数据 ,对零点行动前后太湖各监测点位的水质状况及DO、CODMn、TP、TN、Chla等主要指标的空间分布进行了对比 ,发现污染状况并未得到明显改善 ,除了人为因素外 ,非点源污染的贡献和底泥营养物质的释放是影响水质改善的 2个重要因素     

泥沙灾害和泥沙环境快速评估方法研究

泥沙灾害可以看作是泥沙环境突变或渐变积累到一定条件下发生变异时的表现形式,各类泥沙灾害和泥沙环境都具有不同的内涵和表现方面, 因此泥沙灾害和泥沙环境的评估应具有不同的对象。一旦研究的对象被确定,泥沙灾害的表现因子组合便可明确。类似地泥沙环境的环境变量和总体状况的指示怀变量也可确定。为了便于了解泥沙灾害和泥沙环境的关系,并提高评估效率,可将泥沙灾害和泥沙环境快速评估的参照组建立在能够包括影响二者表现特征的诸环境变量的最小图斑上,通过选取适当参照点,分类确定不同参照组,利用待评估地点孕灾环境因子（或环境变量）与不同参照组的相似分析。预测评估点的泥沙灾害和泥沙环境表现因子特征和动态过程.     

Effect-Directed Analysis of Key Toxicants in European River Basins. A Review (9 pp)

Background, Aim and Scope Extensive monitoring programs on chemical contamination are run in many European river basins. With respect to the implementation of the European Union (EU) Water Framework Directive (WFD), these programs are increasingly accompanied by monitoring the ecological status of the river basins. Assuming an impact of chemical contamination on the ecological status, the assignment of effects in aquatic ecosystems to those stressors that cause the effects is a prerequisite for taking political or technical measures to achieve the goals of the WFD. Thus, one focus of present European research is on toxicant identification in European river basins in order to allow for a reduction of toxic pressure on aquatic ecosystems according to the WFD. Main Features: An overview is presented on studies that were performed to link chemical pollution in European river basins to measurable ecotoxic effects. This includes correlation-based approaches as well as investigations that apply effect-directed analysis (EDA) integrating toxicity testing, fractionation and non-target chemical analysis. Effect-based key toxicants that were identified in European surface waters are compiled and compared to EU priority pollutants. Further needs for research are identified. Results: Studies on the identification of effect-based key toxicants focused on mutagenicity, aryl hydrocarbon receptor-mediated effects, endocrine disruption, green algae, and invertebrates. The identified pollutants include priority pollutants and other well-known environmental pollutants such as polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins, furans, and biphenyls, nonylphenol, some pesticides and tributyltin, but also other compounds that were neither considered as environmental pollutants before nor regulated such as substituted phenols, natural or synthetic estrogens and androgens, dinaphthofurans, 2-(2-naphthalenyl)benzothiophene, and N-phenyl-2-naphthylamine. Discussion: Individual studies at specific sites in a European river basin demonstrated the power of combined biological and chemical analytical approaches and, particularly, of effect-directed analysis. However, the available information on effect-based key toxicants is very limited with respect to the entirety of rivers possibly at risk due to chemical contamination and with respect to toxicological endpoints considered at a specific site. A relatively broad basis of information exists only for estrogenicity and aryl hydrocarbon, receptor-mediated effects. Conclusions: The development of tools and strategies for an identification of key toxicants on a broader scale are a challenging task for the next years. Since investigations dealing with toxicant identification are too labor and cost-intensive for monitoring purposes, they have to be focused on the key sites in a river basin. These should include hot spots of contamination, particularly if there is evidence that they might pose a risk for downstream areas, but may also involve accumulation zones in the lower reach of a river in order to get an integrated picture on the contamination of the basin. Perspectives: While EDA is almost exclusively based on measurable effects in in vitro and in vivo biotests to date, an increasing focus in the future should be on the integration of EDA into Ecological Risk Assessment and on the development of tools to confirm EDA-determined key toxicants as stressors in populations, communities and ecosystems. Considering these requirements and applied in a focused way, toxicant identification may significantly help to implement the Water Framework Directive by providing evidence on the main stressors and possible mitigation measures in order to improve the ecological status of a river ecosystem.     

Exploratory study of suspended sediment concentrations downstream of harvested peat bogs

Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline should be reviewed.     

The role and distribution of total suspended solids in the macrotidal coastal waters of Korea

Spatial and temporal distribution patterns of total suspended solids (TSS) in the shallow and macrotidal regions of the Korean peninsula indicated there were significant changes in TSS concentrations. These were seasonally influenced by the wind, river input and tidal cycle. There were high TSS values at estuarine and river mouth stations and during low tide due to the re-suspension of bottom sediment by strong wind action during winter months, in addition the land input through rivers and strong tidal current during ebbing. Monthly mean values of TSS significantly correlated with wind speed and nitrate concentration (p < 0.01). This indicated that the resuspension of surface sediment was a more important source of TSS than the river input, and that nitrate was introduced into the water column during the resuspension process. TSS were seven times higher at low tide than in high tide. Light penetration was significantly inhibited by TSS; as >98% of incident light was absorbed within 2 m and zero photosynthetically active radiation (PAR) under 2 m in the estuarine stations during winter. Removal of heavy metals and nutrients by TSS in the water column was evident. Over 80% of the initial concentration of nutrients was removed within 10 min under various concentrations of TSS and also TSS contained significantly higher concentration of heavy metals than surface sediment. The concentration levels of nutrients and chemical oxygen demand in the west coast were comparable with the East and South Sea, even the major rivers in the Korean peninsula flow into the West Sea with major pollutant loadings into the coastal areas. High concentration of TSS is likely to contribute to the removal process of these pollutants, resulting in relatively lower levels of nutrients and organic materials in these coastal waters.     

浙江某农场土壤和沟渠沉积物对氨氮的吸附研究

通过静态吸附实验,研究农田土壤及沟渠沉积物对氨氮的吸附作用.实验表明,水相氨氮浓度为5～100 mg/L时,风干农田土壤、风干沟渠沉积物及新鲜沟渠沉积物3种吸附剂的吸附等温线均呈良好线性关系,并符合Freundlich吸附模式;农田土壤与沟渠沉积物的氨氮背景含量分别为12 mg·kg^-1和92 mg·kg^-1,并且农田土壤对氨氮的吸附系数为8.21,而风干沟渠沉积物与新鲜沟渠沉积物吸附系数分别为5.42与6.84,因此,土壤的吸附能力要大于沟渠沉积物,后两者的吸附能力相近.对3种吸附剂吸附机制的讨论表明,吸附特性与界面性质相关,实验氨氮浓度范围内吸附作用主要为离子交换.相同实验条件下,当初始氨氮浓度较大时,随温度升高,3种吸附剂对氨氮的平衡吸附量减小,对氨氮的吸附为弱放热过程.     

黄河(内蒙古段)水体中沉积物的表面特征

运用表面络合原理,研究了内蒙古清水河县喇嘛湾黄河干流沉积物的表面特征.根据酸碱滴定求得沉积物的零电点pH(PZC),表面质子电荷密度σH及总吸附位NS,运用恒定容量模式求定了样品的表面固有酸度常数.研究表明,应用恒定容量模式研究天然水体沉积物的表面特征是可行的,在一定程度上能较好地吻合实验数据.     

不同河流水体颗粒物对硝化过程的影响

采用模拟实验的方法对比研究了长江和黄河水体颗粒物对硝化过程的影响.结果表明:(1)当颗粒物含量分别为0g·l-1和2g·l-1时,长江水样的平均硝化速率在前10d分别为0.21mg·l-1·d-1和0.70mg·l-1·d-1,黄河水样分别为0.18mg·l-1·d-1和0.32mg·l-1·d-1.采用Logistic模型对氨氮的硝化作用进行拟合发现,颗粒物含量为2 g·l-1时的硝化速率常数均显著高于无颗粒物存在时的硝化速率常数,说明有颗粒物存在时的硝化过程较快.(2)有颗粒物存在时,水体氨化细菌、亚硝化细菌和硝化细菌的数量均显著高于无颗粒物存在的水体,而且长江水样中各种菌的数量明显高于黄河水样.(3)长江水样中氨氮的平均硝化速率和硝化速率常数明显大于黄河,这是由于长江水样较高的细菌浓度水平和两条河流颗粒物不同的理化性质所导致.     

零价铁表面积对泥浆反应体系中硝基苯降解行为的影响

硝基苯能够被零价铁还原成为苯胺. 利用气相色谱分析方法,研究了泥浆体系中零价铁表面积对硝基苯污染底质降解行为的影响. 结果表明,在沉积物中初始w(硝基苯)为8.87 μg/g,按照3.27 g/L最佳比例投加还原铁粉,经2 h反应约有97%的硝基苯被降解;其还原机理为表面接触反应,铁粉总表面积是影响硝基苯降解的主要参数;沉积物中硝基苯降解速率常数(K)和残留量(y)与单位体积泥浆中零价铁总表面积(ρ_a)之间表现为线性和负指数相关性,其关系式分别为:K0.006　5+5.165　87×10－4ρ_a和y8.57exp(-ρ_a/7.66)+0.25;零价铁还原硝基苯的降解过程,其降解动力学符合准一级方程,并且通过SEM扫描电镜发现零价铁在反应过程中表面被严重腐蚀,颗粒组成发生明显改变.