近岸海域沉积物重金属生态风险评价模型对比研究

重金属污染被认为是2l世纪影响人类生存与健康的重要环境问题，该类物质极易在近岸海域沉积环境富集，因此海洋沉积物重金属污染已成为人们关注的全球性的环境问题之一，而重金属生态风险评价则成为污染生态学研究的前沿。综述了重金属的形态及生物有效性、重金属污染程度评价方法、重金属生态效应评价法等3种典型生态风险评价方法，结合国内外研究现状对不同的生态风险评价的方法和技术手段进行对比研究，并讨论了相关模型的适用范围及局限性。主要结论如下：金属的赋存形态是基于操作定义的，采用不同的提取方法及提取过程中使用的不同试剂都会对分析结果产生影响；重金属污染程度评价方法难以反映沉积物中重金属的化学活性和生物可利用性；生态效应评价方法从重金属的生物毒性角度出发，反映了多种污染物的综合影响，但该评价方法没有考虑环境条件对元素地球化学分布的影响。因此，在进行近岸海域沉积环境重金属生态风险评价时，采用多种方法相结合的综合评价是解决实际问题的有效途径。

A COMPARISON STUDY OF ECOLOGICAL ASSESSMENT MODEL ON HEAVY METALS OF OFFSHORE SEDIMENTS

Heavy metal contamination in offshore is a worldwide problem,because these metals are generally indestructible and most of them can cause heavy damages to coastal ecological environments and systems.Those pollutions are mainly transported into coast and adjacent sea by input and/or industrial wastewaters discharge.Most Heavy metals,especial for particle-active components,are deposition in coastal sedimentary environment.Sediments are the main repository and source of heavy metals in the aquatic environment and play an important role in the transport and storage of potentially hazardous metals.The paper reviewed the ecological risk assessment methods on heavy metals in coastal sediments,including how the chemical forms or type of the binding of metals act on bioavailability,pollution degree evaluation by contamination index,and ecological effect assessment of heavy metals based on ecological risk index.The advantages and disadvantages of those methods were also compared and discussed.Assessing sediment pollution by using the heavy metal chemical form might not firmly guarantee the occurrence of deleterious ecological effects.Contamination index could hardly give comprehensive and systematic information about bioavailability of heavy metals.The ecological risk index have been derived with a variety of both theoretical methods that rely upon equilibrium partitioning models and empirical methods that rely upon analyses of matching,field-collected chemistry,and biological effects data.But evaluation on the potential ecological risk of heavy metals based on ecological risk index might lose information about environmental effects on heavy metals.To sum up,the evaluation together with the different methods should be a useful crosscheck for us in the assessing process.