Research on the Variation Characteristics and Influencing Factors of COD in Erhai Lake in 2015-2019
The concentration of organic pollutants,represented by COD and permanganate index,has become a major factor affecting the water quality category of Erhai Lake.In this study,the characteristics of COD changes in Erhai Lake and the main rivers and ditches entering the lake were investigated by monitoring the water quality.The Mann-Kendall trend test and Morlet wavelet analysis methods were applied.The results indicated that the historical trend of COD in Erhai Lake had much obvious variation characteristics between years or months within a year,and the COD in Erhai Lake has changed from a decreasing trend to an increasing trend in recent years,with the abrupt change occurring between 2017 and 2018,during which no abrupt changes had occurred in the inflow COD load and meteorological conditions,while the correlation between COD and inflow COD load in Erhai Lake gradually decreased,and correlation with chlorophyll and phytoplankton increased,reflecting that COD in Erhai Lake tended to be impacted by endogenous phytoplankton sources.
chemical oxygen demandchracteristics of changeabrupt detectionchlorophyll-aErhai Lake
NETL
NSTL
万方数据
