东江湖上游浙水流域水质评价与污染源解析

    Water Quality Evaluation and Pollution Source Analysis of Zheshui River Basin in the Upper Reaches of Dongjiang Lake

    • 摘要: 东江湖是湖南省及长株潭城市群重要饮用水源地, 浙水河作为其上游一级支流, 是东江湖重要的生态安全屏障。在积极发展蔬菜、茶果、生态养殖等区域特色农业集群背景下, 浙水河水环境现状及污染来源尚不清晰。基于流域实测水质数据, 运用水污染指数(WPI)、期望值-阈值的水质健康评估法(ETI)和水质质量指数(WQI)进行水质评价, 并采用主成分分析(PCA)方法识别流域主要污染物及关键源区, 最后利用绝对主成分-多元线性回归(APCS-MLR)模型和输出系数法定量解析主要污染源及其贡献率。结果表明: (1)2016-2022年浙水流域水质整体呈先波动恶化后逐步改善趋势, 但总氮(TN)浓度长期超标, 属Ⅳ类水, TN是影响下游东江湖水环境的关键因子。(2)浙水流域水质呈现上游和下游较好, 中游较差, 尤以县城附近最差的空间格局, 表明流域水污染主要受外源污染影响。(3)提取的3种主成分可解释88.77%的原始变量信息, 水体有机污染物(F1)占38.29%, 氮污染物(F2)占34.86%, 磷污染物(F3)占15.62%。F1主要来自生活源+农业面源(以畜禽养殖为主); F2主要来自生活源+农业面源(以种植业为主), 卢阳镇和土桥镇是关键源区; F3主要来自农业面源(以畜禽养殖为主)+生活源, 马桥镇和泉水镇是关键源区。浙水流域未来要针对关键源区加强农业面源污染的精准治理, 这对保护浙水河及下游东江湖的水环境具有重要意义。

       

      Abstract: Dongjiang Lake is an important drinking water source in Hunan Province and a strategic water source for Changsha-Zhuzhou-Xiangtan City Group. Zheshui River, as its upper level tributary, is an important ecological security barrier in Dongjiang Lake. Currently, under the background of active development of regional agricultural clusters such as vegetables, tea, fruits and ecological breeding, water environment status and pollution sources of Zheshui River are still unclear. Based on measured water quality data of basin, water quality assessment was conducted using water pollution index (WPI), water quality health assessment (ETI) and water quality index (WQI), and principal component analysis (PCA) to identify the main pollutants and key source areas of the basin. Finally, absolute principal component-multiple linear regression (APCS-MLR) model and output coefficient method were used to analyze the main pollution sources and their contribution rates. The results show that: (1) From 2016 to 2022, overall water quality of Zheshui River Basin showed a trend of fluctuating deterioration followed by gradual improvement, but concentration of total nitrogen (TN) exceeded the standard for a long time, belonging to Class Ⅳ water. TN was a key factor affecting water environment of Dongjiang Lake in the downstream. (2) The water quality of Zheshui River Basin was better in the upper and lower reaches, and worse in the middle reaches, especially the worst spatial pattern near the county seat, which indicate that water pollution of the basin was mainly affected by exogenous pollution. (3) The extracted three principal components could explain 88.77% of original variable information, organic pollutants (F1) accounted for 38.29%, nitrogen pollutants (F2) accounted for 34.86%, and phosphorus pollutants (F3) accounted for 15.62%. F1 mainly came from living source + agricultural non-point source (mainly livestock and poultry breeding); F2 mainly came from living source + agricultural non-point source (mainly planting), Luyang Town and Tuqiao Town were the key source areas; F3 mainly came from agricultural non-point source (mainly livestock and poultry breeding) + living source, and Maqiao Town and Quanshui Town were the key source areas. In the future, the precise control of agricultural non-point source pollution should be strengthened in key source areas of Zheshui River Basin, which was of great significance to protect the water environment of Zheshui River and Dongjiang Lake in the downstream.

       

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