Analysis of Morphological Factors Contributing to Chemical Oxygen Demand in the Water Body of Yilong Lake
Chemical oxygen demand(COD)is a common indicator of eutrophication in lakes.Understanding the composition of COD occurrence matter is crucial for effective COD reduction.Previous studies have primarily focused on the contribution of inorganic ions and dissolved organic matter to COD,while research on the contribution of suspended particles in COD has been limited.In this study,we examined Yilong Lake in Yunnan Province,a lake with persistently high COD levels.We designed four water sample processing methods based on the composition and morphological characteristics of suspended particles in Yilong Lake,including settling,filtration through screens with different pore sizes,centrifugation,and filtration through 0.45 μm glass fiber filter membrane.We compared the effectiveness of these methods in reducing COD and different particles,and explored the contribution of different morphological matter to COD in Yilong Lake.The results showed that Cylindrospermopsis raciborskii and soluble reducible matter were the main contributors to COD in Yilong Lake,and the high-density Cylindrospermopsis raciborskii and their metabolic products were the direct cause of consistently high COD levels in the lake.Therefore,efforts to improve water quality in Yilong Lake should focus on addressing endogenous pollution,particularly the factors leading to the formation of Yilong Lake's unique community of planktonic algae dominated by Cylindrospermopsis raciborskii.This approach may help identify more fundamental measures for reducing COD in Yilong Lake from the source.
chemical oxygen demandoccurrence matterCylindrospermopsis raciborskiireduction of endogenous pollution
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