水体沉积物重金属污染风险评价研究进展

Research Progress of Risk Assessment of Heavy Metals Pollution in Water Body Sediments

沉积物是水体中重金属的主要富集地,对水体沉积物中重金属进行风险评价,是了解水体中重金属污染状况的有效手段,可以为管理部门提供决策依据。文章分析了中国水体沉积物重金属风险评价的研究对象及评价标准,综述了国内外目前常用的水体沉积物重金属污染风险评价方法。中国目前水体沉积物风险评价涉及的水体主要为湖泊、河流、水库及海洋,且对湖泊及河流的重金属污染风险评价研究多于水库及海洋。水体沉积物重金属风险评价涉及的重金属有Hg、Cd、Cr、Pb、Mn、Cu、Zn、Ni、Co,As等,其中在90%以上的水体沉积物重金属风险评价中涉及到Pb、Cu、Zn,说明这3种重金属污染最广,其次为Cd、Cr、As,重金属W在水体中的风险性未得到重视。水体沉积物重金属污染风险评价所涉及的评价指标有重金属含量、重金属的形态分布和空间分布特征等,主要以重金属的含量作为风险评价的指标,其次是分析重金属的空间分布特征,对重金属形态分布分析较少。中国水体沉积物重金属风险评价标准还不完善,标准的选择较为多样,需根据评价目地、水体情况选择合适的评价标准。国内外目前常用的水体沉积物重金属污染风险评价方法主要包括地累积指数法、沉积物富集系数法、沉积物质量基准法、潜在生态风险指数法、污染负荷指数法、尼梅罗综合指数法、次生相与原生相比值法等,并分析了各评价方法的优缺点,其中地积累指数法、沉积物富集系数法、污染负荷指数法、尼梅罗综合指数法未引入生物有效性,潜在生态风险指数法考虑了生物毒理学和生态学内容,但也存在不足之处。指出针对水体沉积物中重金属毒害的健康风险评价较少,对于不同毒性数据的归一化方法和原理有待进一步研究。

Sediments are the main enrichment of heavy metals in water.Risk assessment of heavy metals in sediments is an effective means to understand the pollution status of heavy metals in water.Moreover,it provides a decision making basis for water management departments.This paper analyzes the study object and the assessment criterion of risk assessment of heavy metals in water body sediments.It also summarizes several assessment methods commonly adopted at home and abroad.The risk assessment is conducted mainly in lakes,rivers,reservoirs,and seas.The risk of heavy metal pollution is found more in lakes and rivers than in reservoirs and seas.Heavy metals for risk assessment are Hg,Cd,Cr,Pb,Mn,Cu,Zn,Ni,Co,and As.More than 90% of the water body sediments in the risk assessment of heavy metals comprised Cu,Zn,and Pb.These heavy metal pollutants are the most extensive,followed by Cd,As,and Cr.The risk of heavy metal W is not taken seriously.The assessment indexes of risk assessment include content,fraction distribution,and spatial distribution.The content of heavy metals is the main assessment index,followed by the spatial distribution characteristics of heavy metals.Analysis on speciation distribution of heavy metals is minimal.The assessment criteria in China are not perfect,and choices of criteria are diverse.The appropriate assessment criteria should be selected according to the assessment purpose and water body condition.Several assessment methods commonly adopted at home and abroad are geoaccumulation index method,enrichment factor method,sediment quality standard method,potential ecological risk index method,pollution load index method,Nemerow index method,and the ratio of secondary and primary phases.The advantages and disadvantages each of these methodsare analyzed.Biological effectiveness is not considered in geoaccumulation index method,enrichment factor method,pollution load index method,and Nemerow index method.The potential ecological risk index method takes into account biological toxicology and ecology; however,shortcomings are also found.This paper emphasizes that research on the health risk assessment of toxicity of heavy metals in sediments is minimal.The normalization method and principle of different toxicity data need to be further researched.