卫河流域河南段不同时期水环境风险评估

Water environmental risk assessment across different periods in the Henan section of the Wei River basin

为了评估卫河流域河南段不同时期水环境风险,选取卫河流域4个监测断面和3种水体污染物[化学需氧量(COD)、氨氮(NH_(3)-N)和总磷(TP)]的监测数据,通过建立边缘分布函数和优选Copula函数构建适宜的水体污染物三维联合风险分布模型,分析了不同时期卫河流域水体污染物的组合风险概率。结果表明:监测断面卫辉皇甫(非汛期和汛期)、浚县王湾(非汛期)和大名龙王庙(非汛期和汛期)的水体污染物间拟合优度最好的三维Copula函数为Gaussian Copula函数,监测断面浚县王湾(汛期)和汤阴五陵(非汛期和汛期)的水体污染物间拟合优度最好的三维Copula函数为t Copula函数;在非汛期和汛期大名龙王庙水体污染物均处于Ⅰ~Ⅲ类水质标准的联合概率最大,分别为26.30%和21.61%,卫辉皇甫水体污染物至少有一个指标处于劣Ⅴ类水质标准时的联合风险概率最大,分别为52.34%和56.53%;当仅NH_(3)-N处于劣Ⅴ类水质标准时,监测断面卫辉皇甫、浚县王湾、汤阴五陵和大名龙王庙非汛期水体污染物的联合风险概率分别为25.68%、22.94%、24.68%和13.47%,汛期水体污染物的联合风险概率分别为28.01%、10.31%、6.16%和4.12%;在非汛期和汛期监测断面卫辉皇甫和浚县王湾主要受工业废水和生活污水污染的影响且其主导水体污染物均为NH3-N,在汛期时监测断面汤阴五陵和大名龙王庙主要受农业面源污染的影响且其主导水体污染物由非汛期的NH3-N转变为汛期的TP。研究表明,受到不同污染源的影响卫河流域河南段不同时期水体污染物的联合风险概率具有一定的差异性。

In order to evaluate the water environmental risk in the Henan section of the Wei River basin across different periods,monitoring data on three kinds of water quality indicators[chemical oxygen demand(COD),ammonia nitrogen(NH3-N)and total phosphorus(TP)]were selected at four monitoring sections.The appropriate three-dimensional joint risk probability distribution model of water pollutants was constructed by establishing the marginal distribution function and the optimal Copula function,and the combined risk probability of water pollutants in different periods was analyzed.The results showed that the Gaussian Copula function was the best three-dimensional Copula function for the water pollutants in the monitoring sections of Weihui Huangfu(non-flood season and flood season),Xunxian Wangwan(non-flood season)and Daming Longwangmiao(non-flood season and flood season),and t Copula function were the best three dimensional Copula function for the water pollutants at Xunxian Wangwan(flood season)and Tangyin Wuling(non-flood season and flood season).The maximum joint probabilities were respectively 26.30% and 21.61% in non-flood season and flood season at Daming Longwangmiao when the water pollutants were in the Ⅰ–Ⅲ water quality standard,while the maximum joint risk probabilities were 52.34% and 56.53% in non-flood season and flood season at Weihui Huangfu when at least one index of the water pollutants was in the inferior Ⅴ water quality standard.The joint risk probabilities of the water pollutants in non-flood season were 25.68%,22.94%,24.68% and 13.47% at Weihui Huangfu,Xunxian Wangwan,Tangyin Wuling and Daming Longwangmiao,respectively when only NH_(3)-N was under the quality standard of inferior Ⅴ,while the joint risk probabilities of the water pollutants in flood season were 28.01%,10.31%,6.16% and 4.12%,respectively.The monitoring sections of Weihui Huangfu and Xunxian Wangwan were mainly affected by industrial wastewater and domestic sewage pollution during the non-flood and flood seasons,and the dominant water pollutant was NH_(3)-N.The monitoring sections of Tangyin Wuling and Daming Longwangmiao were mainly affected by agricultural non-point sources of pollution during the flood season,and the dominant water pollutant changed from NH3-N during the non-flood season to TP in flood season.The joint risk probabilities of water pollutants in the Henan section of the Wei River basin were different in different periods.