丽江拉市海湖库水环境质量变化趋势分析及预测

The Analysis and Prediction of the Water Quality of Lashi Lake in Lijiang

为研究丽江拉市海近年水质变化情况,对拉市海2018—2021年营养化状态指数和内梅罗污染指数进行Spearman相关分析,对监测项目变化趋势、单因子污染指数和主成分进行分析,对出现过超标情况的pH值变化原因进行分析,应用时间序列预测传统模型预测了2022年拉市海水质,为生态环境部门保护拉市海提供了思路和方法。研究结果显示:拉市海内梅罗污染指数显著升高,营养化状态指数变化趋势不显著,整体水质变差;监测项目结果无显著变化,有7个监测项目单因子污染指数超过0.5,其中pH值最高,主成分分析结果表明目前影响拉市海水环境质量的主要项目涉及到拉市海中的耗氧物质、溶解氧浓度、酸碱性和氮磷循环;pH值随月份规律变化,预测2022年pH值在8月和9月可能出现超标情况,2022年年均值能达到Ⅲ类标准。

This paper analyzed the change of water quality of Lashi Lake in Lijiang,the status index of eutrophication and the pollution index of Nemerow were analyzed by Spearman correlation from 2018 to 2021,the change trend of monitoring items,the pollution index of single factor and the principal component were analyzed.The reason of p H value exceeding the national standard was analyzed.The traditional time series model was used to predict the sea water quality in 2022 in Lashi Lake.It provided protection ideas and methods for the lake.The results showed that the pollution index of Nemerow in Lashi Lake increased significantly,the change trend of nutritional state index was not significant,and the whole water quality became worse.The results of principal component analysis showed that the main items affecting the water quality of the Lake were related to the oxygen-consuming substance,dissolved oxygen concentration,acidity,alkalinity,nitrogen and phosphorus cycling in the Lake.The pH value in 2022 was expected to exceed the standard in August and September,and the annual average in 2022 would meet the category III standard.