应用概率物种敏感度分布法研究太湖重金属水生生物水质基准

目前广泛使用的水质基准推导方法—物种敏感度分布法存在曲线拟合模型不确定、曲线拟合效果不佳、种内差异欠考虑、基准值不准确等诸多问题,概率物种敏感度分布法可有效解决上述问题。应用概率物种敏感度分布法构建了太湖水体中5种重金属Ag、Pb、Cd、Hg和Zn的概率物种敏感度分布曲线,在此基础上得到了保护水生生物的急性水质基准分别为1.079μg·L~(-1)、637.973μg·L~(-1)、19.465μg·L~(-1)、8.729μg·L~(-1)和105.506μg·L~(-1),慢性水质基准分别为0.108μg·L~(-1)、63.797μg·L~(-1)、1.947μg·L~(-1)、2.340μg·L~(-1)和52.753μg·L~(-1);不同类群间生物对重金属的敏感度存在差异,不同重金属对同一类群生物的毒性也存在差异;通过与国内外已有的重金属水质基准值比较,发现水质基准具有明显的区域性,目前基于国外水质基准或我国整体水域特点来制定的太湖水质标准,往往造成对太湖水生生物欠保护或过保护的状况。

Deriving Aquatic Water Quality Criteria for Heavy Metals in Taihu Lake by Probabilistic Species Sensitivity Distribution

The widely used method of species sensitivity distribution has a number of disadvantages, such as the uncertainty of statistical models, the undesirable effectiveness of fitted curve, the deficient consideration for in-traspecies variation and the inaccuracy of water quality criteria. The method of probabilistic species sensitivity dis-tribution (PSSD) can solve these problems effectively. Probabilistic species sensitivity distribution curves and water quality criteria for 5 heavy metals (Ag, Pb, Cd, Hg and Zn) in Taihu Lake were achieved by the method of PSSD. The derived acute criteria for 5 heavy metals were 1.079 μg?L-1, 637.973 μg?L-1, 19.465 μg?L-1, 8.729 μg?L-1 and 105.506μg?L-1, respectively. The corresponding chronic criteria were 0.108μg?L-1, 63.797μg?L-1, 1.947μg?L-1, 2.340μg?L-1 and 52.753μg?L-1, respectively. In this study, sensitivities of different taxa to heavy metals and toxicities of different heavy metals to same taxa were compared and analyzed. Finally, the results were compared with other existing values and distinct regional differences in water quality criteria were discovered. The present water quality standards of Taihu Lake based on the existing water quality criteria might cause aquatic organisms under protection or overprotection.