洋河水质现状及其成因分析

Present situation of Yanghe water quality and analysis of its causes

为探究洋河水质现状,利用2017年11月至12月水质实测数据,分析了洋河10项水质指标的异质性及其成因。结果表明:(1)单因子指数评价结果:洋河总体水质较差,不同地段差异明显。基于各断面水质现状与评价结果来看,总体达标率为25%,下游污染较严重达标率为0%,主要超标因子为COD、TP、DO、NH4+-N和浊度。(2)分析上下游水质变化特征,发现上游水体中浊度变异系数最大,其次是TP和BOD5;下游水体中TP变异系数最大,其次是BOD5,表明水质呈现一定变异性。(3)基于遥感影像,提取河岸两侧一定范围内的土地利用类型并与水质要素进行相关性分析,洋河上游主要以面污染源为主,下游主要以点源污染为主。耕地、城镇、建设用地、水面和草地对水质的影响较显著。(4)统计分析流域区县社会经济结构并建立与水质要素间相关关系,结果显示洋河流域水生生态系统较脆弱,下游受工业企业的污染贡献较大。人口、农产品、水产品产量和综合能源消耗量对水质影响显著。

The water quality of Yanghe River between November and December 2017 was monitored, with spatial heterogeneities and their dependencies of ten indices analyzed. The results show that:(1) Based on the results of single-factor pollution index, the overall water quality of Yanghe River was poor, and presented distinct spatial differences. The water quality evaluation results of only 25% of the sampling sites along the river met the standard. Water quality in the downstream became even worse, with none of the water samples collected meeting the standard. The main indices which exceeded the standard included COD, TP, DO, NH4+-N and turbidity.(2) Spatial variation of the water quality was observed. In the upstream, the coefficient of variation of turbidity was the greatest, followed by TP and BOD5;while in the downstream, the coefficient of variation of TP was the greatest, followed by BOD5.(3) The correlation between water quality and land use types within a certain range of river banks on both sides extracted by remote sensing data was conducted. In the upstream, non-point sources were the dominant pollution sources;while in the downstream, point sources were dominant. The water quality was significantly affected by cropland, town and construction land, water surface and grassland.(4) The correlation between water quality and socio-economic factors of counties in the river basin was analyzed. The aquatic ecosystems in the Yanghe River Basin were relatively vulnerable, and the downstream of river was heavily polluted by the industry. Socio-economic factors such as population, agricultural products, aquatic production and integrated energy consumption had significant impacts on water quality.