SPATIOTEMPORAL VARIATION OF WATER QUALITY AND ALGAL BIOMASS IN ERHAI LAKE AND ITS ENVIRONMENTAL MANAGEMENT IMPLICATIONS

Highlights

● The water environment of Erhai Lake has shown satisfactory, declining and improving.

● Total N and P, and chemical oxygen demand as key water environment indicators.

● Pollution load distribution and control measures are key to Erhai Lake management.

Abstract

Elucidating the spatiotemporal pattern of water quality and algal biomass is crucial for accurately tracing pollution sources and reducing the risk of algal blooms in lake systems. This study analyzed the spatiotemporal variability of water quality and algal biomass in Erhai Lake from 1994 to 2021 using water quality index (WQI), Mann-Kendall test and Sen’s slope combined methods. The potential causes of water quality deterioration and algal biomass dynamics were also elucidated. The results showed that the historical changes in the water environment of Erhai Lake mainly had three stages: satisfactory (1994‒2001), deteriorating (2002‒2010) and improving (2011‒2021). The changes in water quality and algal biomass were primarily affected by total nitrogen, total phosphorus and chemical oxygen demand in different stages. The water environment of Erhai Lake is currently improving significantly, starting in the southern area that is furthest from the sources of agricultural pollution, especially in summer and autumn. This is attributed to the implementation of control measures resulting in lower pollutant loads at particular times and places. Therefore, it is necessary to continue to promote standardized livestock farming, to strengthen rural wastewater collection and to investigate measures such as the interruption of the endogenous cycle.

Graphical abstract

Keywords

Erhai Lake / control measures / water environment / water quality index (WQI)

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Supplementary materials

The online version of this article at https://doi.org/10.15302/J-FASE-2023520 contains supplementary materials (Tables S1–S3).

Acknowledgements

This research was supported by the Major Science and Technology Special Plan of Yunnan Province (202202AE090034), the National Natural Science Foundation of China (U1902207), and the Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed (2023PL00X).

Compliance with ethics guidelines

Xiaofei Liu, Yue Wu, Zhaokui Ni, and Shengrui Wang declare that they have no conflicts of interest or financial conflicts to disclose. This article does not contain any studies with human or animal subjects performed by any of the authors.

RIGHTS & PERMISSIONS

The Author(s) 2023. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)