摘要:
铜是生物必需的微量元素,但过量暴露会对生物产生毒害效应。针对我国南方城市某湿地生态保护区水体重金属污染问题,参照《澳大利亚和新西兰淡水和海水水质指南》,应用物种敏感度分布(speeies sensitivity distribution,SSD)方法和联合概率曲线(joint probability curve,JPC)方法评价水体中铜的生态风险评价,在此基础上提出水体中铜浓度的管理限值。根据该湿地生态保护区生物调查历史数据以及其他文献数据,整理了415个本地物种的清单,通过美国环境保护署ECOTOX数据库以及其他文献共获取了13个物种的毒性数据,构建了Weibull分布、对数正态分布、正态分布、对数Logistic分布、Logistic分布、BurrⅢ型分布和Gumbel分布等7个SSD模型。结果表明,利用13个本地物种铜毒性数据构建的SSD模型具有合理性,不同模型计算得到的湿地生态保护区水体中铜的总体风险期望值为0.054~0.121。其中,BurrⅢ型分布模型的拟合效果最好,据此推导得到以保护水生生态系统为目标的铜的高可靠性与中等可靠性触发值分别为2.55μg·L-1和1.41μg·L-1。考虑到管理目标的可达性和现状的生态风险水平,提出该湿地生态保护区水体中铜浓度的管理限值为3μg·L-1。
Abstract:
Copper is one of the essential micronutrients for all living organisms,whereas abnormal levels of exposure to copper could be toxic.A case study was conducted on a wetland reserve in Southern China which was subjected to heavy metals pollution.Following the Australian and New Zealand Guidelines for Fresh and Marine Water Quality,species sensitivity distribution(SSD) models and joint probability curves(JPCs) were constructed to assess the ecological risk associated with copper in the wetland reserve,and a guideline value of copper in water was proposed.An inventory of 415 native species was created on the basis of the historical biological surveys in the wetland reserve and other literature.Copper toxicity data were collected for 13 native species from the ECOTOX database developed by US EPA,as well as peer-reviewed literature.Seven SSD models were then used to fit the toxicity data including Weibull distribution,Log-normal distribution,Normal distribution,Log-logistic distribution,Logistic distribution,Burr Type III distribution and Gumbel distribution.The SSD models based on the copper toxicity data of the 13 native species could be reasonably interpreted,and the expected total risk given by these models ranged from 0.054 to 0.121.Based on the best fitted SSD model,i.e.Buntype IE distribution,a high reliability trigger value and a moderate one for copper were derived respectively as 255μg·L-1 and 1.41 μg·L-1 for aquatic life protection.Considering the attainability of the management goal and the current level of ecological risk,a guideline value of 3 μg·L-1 was proposed for the water bodies in the wetland reserve.
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