基于环境风险排序的流域优先污染物筛选

Selection of Priority Contaminants in a Watershed Using Risk Ranking Methodology

在流域生态环境治理中,确定治理水体的优先污染物是首先要考虑的问题.环境风险排序方法可利用污染物的毒性值与该污染的暴露浓度值的比值,快速对流域污染物进行风险排序,确定优先污染物.本文以有多年氟化工生产排放历史的大凌河为研究区域,分季节采集18个样点的水体表层样品,分析全氟辛基磺酸(PFOS)、全氟辛酸(PFOA)以及8种常见重金属,并搜集有关当地物种生态毒性的文献资料,确定其优先污染物.结果发现,2011~2016年间,大凌河水体PFOS和PFOA的中位值浓度分别在0.77~3.57 ng·L^(-1)、82.93~344 ng·L^(-1)之间,参照英国水环境对人体健康的潜在风险值发现其均低于标准限值.重金属和有机氯农药的浓度均低于国家Ⅳ级标准,但Hg和As的最高浓度高于Ⅲ级标准.大凌河环境风险值范围为1.42×10-6~2.3×10-2,环境风险排序结果为Cu>Zn>As>p,p'-DDE>p,p'-DDT>Cd>Pb>Hg>PFOA>γ-HCH>Cr>Ni>α-HCH>PFOS.PFOS和PFOA的环境风险排序较为靠后,说明不是该地区需要优先控制的污染物,但长期风险累积不可忽视.Cu是未来大凌河生态环境治理的优先污染物,应重点控制包括造纸厂在内的主要工业企业的生产排放行为.

The present study focuses on the risk rankings of different contaminants from Daling River in Liaoning Province,China,for categorizing the environmental risk levels in the river. Eighteen surface water samples were collected from Daling River,which has been polluted by the surrounding fluorine industries for years. Perfluorooctane sulfonic acid（ PFOS）,perfluorooctanoic acid（ PFOA）and heavy metals were analyzed,and relevant eco-toxicity data obtained from literatures were considered. The median concentrations of PFOS and PFOA were observed as 0. 77-3. 57 ng·L^-1 and 82. 93-344 ng·L^-1,respectively,which were lower than the standard limits of the United Kingdom. The concentrations of heavy metals and organochlorine pesticides（ OCPs） were found to be lower than level Ⅳof the Chinese national environmental quality standards for surface water. The maximum concentrations of mercury（ Hg） and arsenic（ As） were higher than the standard level Ⅲ. The environmental risks ranged from 1. 42 ×10^-6 to 2. 3 ×10^-2 The order of the risks by potential environmental contaminants was Cu Zn As p,p＇-DDE p,p＇-DDT Cd Pb Hg PFOA γ-HCH Cr Ni α-HCH PFOS. The present findings revealed that the environmental risks of PFOS and PFOA were relatively low and these were not taken as priority contaminants,but the accumulation risks could not be overlooked for a long time. Among the contaminants,copper（ Cu） was the priority contaminant of Daling River. Hence,necessary measures are recommended to reduce the potential effects of contaminants on the environment.