基于SSD法的持久性污染物水生态风险阈值研究

The aquatic ecological risk thresholds of persistent organic pollutants based on species sensitivity distribution

应用物种敏感度分布曲线法(SSD)分别计算了DDT、艾氏剂、狄试剂、异狄氏剂、七氯、毒杀酚、林丹、硫丹等8类持久性有机污染物(POPs)对保护95%的淡水生物时在淡水环境中的浓度阈值(HC5),水生生物对不同化学物质的敏感度差异较大,其中对异狄氏剂敏感度最高,其HC5值为0.08μg·L^(-1),对毒杀酚、林丹的敏感性较低,其HC5分别为1.35μg·L^(-1)、1.24μg·L^(-1)。以Sigmoidal型函数为基本模型,采用Sigmoid、logistic、Weibull、Gompertz、Hill、Chapman六种多参数模型分别对DDT的毒理数据进行了浓度对数累积频率拟合,最后确定以Sigmoid,5 parameters函数进行SSD拟合,研究结果表明,八类污染物质的SSD拟合曲线R2均大于0.96,拟合程度高,拟合效果较好,能够反映不同物种毒理数据点的累积概率分布。

This paper estimated the hazardous concentration for 5% of the species（HCs）of eight priority persistent organic pollutants （POPs）, including DDT, Aldrin, Dieldrin, Endrin, Heptachlor, Toxaphene, Lindane, Endosulfan etc. in freshwater environments, by means of Species Sensitivity Distributions （SSD）. The results indicated that the sensitivity of the aquatic organisms was largely different under the different chemical substances. For example, the sensitivity of the Endrin got a top value at 0.08 μg·L^-1, while the sensitivity of the Toxaphene and the Lindane were relatively low at the value of 1.35 μg·L^-1 and 1.24 μg·L^-1, respectively. This paper also used 6 different multiple parameters model including Sigmoid, logistic, Weibull, Gompertz, Hill and Chapman, to fit the DDT toxicological data, and finally determined the model of sigmoid-5 parameters as the optimal SSD fitting model for this research. The results showed that the fitting coefficients （R2） of eight chemicals were all greater than 0.96, which could exactly represent the species cumulative probability distribution of the chemicals＇ toxicological data.