磷素对南漪湖流域水质的影响及其外源性来源分析

为探究磷素对南漪湖近年来水质变化的影响以及定量分析湖泊外源磷污染源结构。于2015—2021年逐月采集南漪湖东湖心、南漪湖西湖心、狮子口3个代表性点位水样，采用单因子评价法、综合污染指数和水污染指数法分别分析了总磷(total phosphorus, TP)、溶解氧、高锰酸盐和氨氮的含量水平，对南漪湖水质的时空变化特征进行了综合性评价以探究磷素与其他指标对水质污染影响的差异。以2017年为基准年，采用改进的输出系数模型对南漪湖流域21个乡镇的外源磷负荷进行分析以确定其主要污染源。结果表明：3种水质评价方法获得的水质评价结果基本相同，2015—2021年南漪湖水质总体呈现逐渐变好的趋势，达到Ⅲ类水质标准；各个指标对南漪湖水质均有一定的影响，但TP是影响南漪湖水质最主要的影响因素，TP判断的水质等级与最终测量的点位水质等级相似；面源污染是主要污染源，其中耕地(包括水田和旱地)污染负荷最大为328.912 1 t/a,其次为建设用地和农村生活污染负荷，占比分别为41.32%和15.32%。研究结果将为南漪湖流域水污染防治提供参考依据，也可以为长江中下游乃至全国典型中小湖泊的污染防治提供参考和...

Effect of phosphorus on water quality in Nan yi Lake Basin and discussion on its exogenous source

In order to explore the effect of phosphorus on the water quality of Nanyi Lake in recent years and to quantitatively analyze the structure of exogenous phosphorus pollution sources in Nanyi Lake. In this study, three representative water samples were collected month by month from 2015 to 2021 in the East Lake, West Lake and Shizikou of Nanyi Lake. The contents of TP, dissolved oxygen, permanganate and ammonia nitrogen were analyzed by single factor evaluation method, comprehensive pollution index and water pollution index method, respectively. The temporal and spatial variation characteristics of water quality in Nanyi Lake were comprehensively evaluated to explore the effects of phosphorus and other indexes on water pollution. Taking 2017 as the base year, the improved output coefficient model was used to analyze the exogenous phosphorus load of 21 villages and towns in Nanyi Lake basin to determine the main pollution sources. The results show that: 1) the water quality evaluation results obtained by the three water quality evaluation methods are basically the same, and the overall water quality of Nanyi Lake is getting better from 2015 to 2021. 2) each index has a certain influence on the water quality of Nanyi Lake, but TP is the most important factor affecting the water quality of Nanyi Lake, and the water quality grade judged by TP is similar to that of the final measurement. 3) non-point source pollution is the main source of pollution, of which cultivated land (including paddy fields and dry land) has the largest pollution load of 328.9121t/a, followed by construction land and rural domestic pollution load, accounting for 41.32% and 15.32%, respectively. The conclusion of this paper will provide a reference basis for the prevention and control of water pollution in the Nanyi Lake basin and can also provide reference and demonstration for the pollution prevention and control of the middle and lower reaches of the Yangtze River and even typical small and medium-sized lakes in China.