基于盲数理论的水体沉积物重金属污染评价模型

针对污染风险评价系统多种不确定信息共存的特点,将盲数理论引入污染评价领域,建立基于盲数理论的地累积指数评价模型.用盲数表示沉积物污染物浓度和地球化学背景值,并通过盲数可靠性分析BM模型和隶属度加权计算得出重金属污染程度等级.将该模型应用于洞庭湖水系沉积物重金属污染的评价,结果表明,这些重金属的富集程度由高至低排列的顺序为:Cd>Cr=Cu=Zn=Hg=As>Pb,Cd是洞庭湖沉积物污染的主要环境污染因子.该模型算出了重金属地累积指数的可能值区间,并且得出与其相对应的可信度水平,进而定量计算出重金属隶属于各污染程度的可能性,它弥补了传统确定性方法的不足,更真实、更客观地表征了评价区域沉积物重金属的富集污染程度.

Assessment model for heavy metal pollution in sediment based on the blind theory

On the basis of the coexistence of multiple uncertainties, blind theory was introduced to the pollution assessment system, and a model of geoaccumulation index based on blind theory was established. With the concentrations of contaminants in the sediment and their values in the geochemical background as blind numbers, the pollution degrees of heavy metals were obtained by using reliability analysis model BM(blind model) and calculating the membership grade. The new model was used to evaluate the heavy metal pollution in sediment from Dongting Lake. The results showed that the order of the geoaccumulation degrees was Cd>Cr=Cu=Zn=Hg=As>Pb. Cd was considered to be the primary important polluting factor in Dongting Lake. Both the possible ranges and their credible degrees of geoaccumulation indices of heavy metals can be calculated in this model, thus the possibilities of heavy metal pollution can be quantitatively calculated. The model reduced the drawbacks in the original assessment, and conveyed information about degree of enrichment more realistically.