1994~2023年滇池水质变化及差异性分析

Analysis of Water Quality Changes and Differences in Dianchi Lake from 1994 to 2023

摘要: 为揭示滇池长期水质演变规律与时空差异特征，基于1994~2023年滇池(草海、外海)水质监测数据，采用单因子评价法，从全湖年均、汛期与非汛期、多年月均等多时间尺度开展描述性分析；另外，选取总氮、总磷、氨氮和高锰酸盐指数为核心指标，分析逐年、多年月度变化情况。运用SPSS、GIS软件，分析各十年段间水质类别差异、汛期与非汛期差异以及空间差异。结果表明：1) 草海和外海高锰酸盐指数、氨氮、总磷和总氮含量均在2013年以后出现明显改善。2) 从年均水质类别来看，滇池草海和外海均表现为汛期劣V类占比高于非汛期，但通过差异性分析，汛期和非汛期不存在显著差异。3) 滇池氮磷比在1994~2023年内呈上升趋势，表现为磷限制为主。4) 滇池外海北部的高锰酸盐指数、氨氮、总磷和总氮均与其它位置存在显著差异。

Abstract: To reveal the long-term evolution and spatiotemporal differentiation characteristics of water quality in Dianchi Lake, based on water quality monitoring data from 1994 to 2023, the single-factor evaluation method was used to conduct descriptive analyses on annual mean, flood season vs. non-flood season, and multi-year monthly water quality across the entire lake. In addition, total nitrogen, total phosphorus, ammonia nitrogen, and permanganate index were selected as core indicators to analyze their annual and multi-year monthly variations. SPSS and GIS software were used to examine the differences in water quality classification among three decadal periods, between flood and non-flood seasons, and across spatial locations. The results show that: 1) The permanganate index, ammonia nitrogen, total phosphorus, and total nitrogen in both Caohai and Waihai have improved significantly since 2013. 2) In terms of annual average water quality classification, both Caohai and Waihai exhibit a higher proportion of inferior Class V water during the flood season than in the non-flood season. However, the difference analysis indicates no significant difference between flood and non-flood seasons. 3) The nitrogen-phosphorus ratio in Dianchi Lake showed an upward trend from 1994 to 2023, indicating a dominance of phosphorus limitation. 4) The permanganate index, ammonia nitrogen, total phosphorus, and total nitrogen in the northern part of Waihai are significantly different from those in other locations.