宜兴市莲花荡水系水环境质量现状及其水质评价

Abstract

莲花荡水系下接乌溪港，是西太湖主要入湖河流之一，水环境功能区划要求其水质达到地表水Ⅲ类。2014年4月(平水期)和7月(丰水期)，对莲花荡水系进行了两次现场调研和采样监测，结果表明：水体中超过Ⅲ类地表水的污染指标主要有高锰酸盐指数、总磷、总氮、氨氮和叶绿素a等，其中氮、磷污染超标严重；受丰水期河水量增加影响，7月份河水水质略优于4月；调研发现，水体主要的污染源为集中畜禽养殖废水、沿岸农村散排生活污水和部分农业面源污染。采用单因子污染指数法、综合水质标识指数法和水体自净能力评价等方法，对莲花荡水系的水环境质量进行了现状评价，结果为：莲花荡水系在平水期和丰水期分别为严重污染和重度污染；综合水质标识类别介于Ⅴ类~劣Ⅴ类黑臭水质之间；水体具有一定的自净能力，且不同时期各河段的自净能力有所不同。 Lianhuadang River System, flowing down with the Wuxi Harbor River, is one of the most important inflow rivers of the West Taihu. Based on the standards of the water environment functional zoning, its water quality should meet the requirement of the Class-III surface water. In April 2014 (average season) and July (abundant season), the field investigation and sampling monitoring have been performed twice respectively in the Lianhuadang River System. The results show that: the contamination indexes in the water exceeding the standard of the Class-III surface water mainly are the permanganate index, the total phosphorus, the total nitrogen, the ammonia nitrogen and the chlorophyll A, of which the contamination of the nitrogen and phosphorus exceed the standard seriously. Due to the influence of the increasing stream flow in abundant season, the water quality in July is slightly better than that in April. According to the survey, the main pollution sources in the water are the waste water of the concentrating livestock and poultry breeding, the coastwise rural domestic sewage, and part of the Agricultural Area Source Pollution . Adopting the single factor contamination index method, the WQI method (the comprehensive water quality identification index method) and the water self-purification ability evaluation method, the results of the current situation evaluation for the water environmental quality of the Lianhuadang Water System show that: most rivers of the Lianhuadang Water System are polluted seriously; the comprehensive water quality identification category is ranged from Class V to inferior class V-stinking sewage; the water body has a certain self-purification ability, and the capacity of self-purification varies in different periods.