应用物种敏感性分布法评估不同形态Cr对海洋生物的生态风险

Abstract

应用生态风险评价中的物种敏感性分布(SSd)方法构建了3种不同形态(Cr、Cr3+、Cr6+)的重金属Cr对海洋生物的SSd曲线。在此基础上计算了3种形态的Cr对不同海洋生物的5%危害浓度(HC5)和其不同暴露浓度对海洋生物的潜在影响比例(PAf),比较了海洋脊椎动物和无脊椎动物对不同形态的重金属Cr的敏感性以及不同形态的Cr的急性生态风险,并且评价了两个港湾海水水体中常见形态的重金属Cr的联合生态风险。结果表明,3种形态的重金属Cr的HC5的大小顺序为Cr3+>Cr6+>Cr。浓度小于10μg/l时,Cr、Cr3+、Cr6+三者生态风险差异不大,且都处于相对较低的水平。在10μg/l的暴露浓度下,三者所影响的海洋生物比例均未超过5%。随着浓度升高,生态风险也相应增大。当浓度达到1 000μg/l时,分别有23.43%,13.73%和17.27%的物种受到Cr、Cr3+、Cr6+的损害,此时三者的生态风险差异也比低浓度时有所增大。当不同形态的重金属Cr浓度在不同的范围时,不同生物的敏感性大小顺序会发生变化。三种形态的重金属对无脊椎动物的生态风险均比脊椎动物(本文即指鱼类)大。两个海湾水体重金属生态风险的大小顺序为宁德海域(0.66%)>福清海域(0.63%)。

Species sensitivity distributions(SSD) method was used to assess the ecological risk of three valence states of Cr(Cr,Cr3+,Cr6+) to marine organisms.The acute toxicity data(LC50 or EC50) were collected from ECOTOX database and SSD curves were fitted based on BurrIII and ReWeibull function.The acute ecological risks of different valence states of Cr and the sensitivity of different marine species(vertebrate and invertebrate) to these different valence states of Cr were compared by the hazardous concentrations for 5% of the species(HC5) and the potential affected fractions(PAF).Then the HC5 values of these different valence states of Cr were in the order:Cr3+> Cr6+> Cr.When exposure concentration was lower than 10 μg/L,no significant differences among the ecological risks of Cr,Cr3+ and Cr6+ was observed.Also,none of these four observations exceeded the threshold of 5%(PAF) at the exposure level of 10 μg/L.The ecological risks of the heavy metals increased as the exposure concentration increased.When came up to 1 000 μg/L,23.43%,13.73% and 17.27% of marine species would be affected by Cr,Cr3+ and Cr6+,respectively.The order of sensitivity to marine species varied with different concentration of heavy metals.The ecological risk of all these three valence states of Cr to invertebrate was higher than to fishes.The case studies showed that the ecological risk of different valence states of Cr in the Seas of Ningde was higher than that in the Seas of Fuqing.