湟水河流域水质时空变化特征及其污染源解析

基于2012—2014年水质数据,综合应用多元统计分析与一维水质模型(Qual2Kw),系统分析了湟水河水质时空变化及其污染物来源.结果表明:湟水河河流水质主要受化学需氧量、生化需氧量、铜、六价铬、水温、溶解氧、总氮、氨氮等8项水质指标影响,且氨氮和总氮污染严重;湟水河水质时间上可划分为3个时段:时段1(6—10月)、时段2(5月和11月)和时段3(12月—4月),时段1水质明显优于时段2和时段3,湟水河水体受工业生活排放污水的影响显著,面源污染对河流水质的影响低于点源污染;空间上可分为3大区段:湟水河上游、中游和下游,中游西宁市段污染较重;基于Qual2Kw模型的污染物贡献比例计算结果揭示了湟水河民和桥断面的氨氮负荷主要来源于扎马隆(S2)-西钢桥(S3),总氮主要来源于报社桥(S5)-小峡桥(S6),其中支流点源是氨氮的主要污染源,普通点源即城镇生活污水和工业废水排放是总氮的主要污染来源,上游干流农田地表径流、畜禽养殖废水、农村生活污水等污染源氨氮、总氮排放也不容忽视.研究结果可以为湟水河流域水环境管理提供科学依据.

Spatio-temporal variation characteristics and water pollution sources in the Huangshui River Basin

Based on the data of water quality from 2012 to 2014, multivariate statistical analysis and one-dimensional water quality model (Qual2Kw) were applied to investigate the temporal and spatial variation of water quality as well as the sources of pollutants in Huangshui River. The results suggest that the water quality of the Huangshui River was affected by eight indexes, including chemical oxygen demand, biochemical oxygen demand, copper, hexavalent chromium, water temperature, dissolved oxygen, total nitrogen and ammonia nitrogen, and the latter two were in serious pollution. The water quality of Huangshui River can be divided according to three periods:period 1 from June to October, period 2 May and November, period 3 from December to April. The water quality of period 1 was obviously better than other periods; Huangshui River water body was significantly affected by the urban sewage and industrial wastewater discharge; while the impact of non-point source pollution was lower than the point source pollution on the river water quality. Huangshui River was classified into three sections:upstream, middle and downstream. Pollution of water quality was more serious in Xining City. Based on the Qual2Kw model analysis, the results of of pollutant sources contribution revealed that the load of ammonia nitrogen to the Minheqiao section in Huangshui River was mainly from the Zhamalong (S2) to the Xigangqiao (S3), and the total nitrogen was mainly from the Baosheqiao (S5) to the Xiaoxiaqiao (S6). The tributaries were the main sources of ammonia nitrogen, and the common point sources of total nitrogen pollution were urban sewage and industrial wastewater discharge. The surface runoff, livestock, poultry breeding wastewater and rural domestic sewage can not be ignored for the sources of nitrogen pollutants. The results of this study can provide a scientific basis for water environment management in Huangshui River Basin.