Temporal–Spatial Variations in Physicochemical Factors and Assessing Water Quality Condition in River–Lake System of Chaohu Lake Basin, China
Wu Li, Kai Liu, Ziqi Wang, Yujie Yang, Rui Sang, Haoyue Zhu, X. Wang, Yuqing Pang, Jiangshan Tong, X. Liu, Mingyue Ma, Qianqian Wang, Kaijun Ma, Liu Fan
Abstract
Eutrophication and algal blooms have frequently occurred in Chaohu Lake. Water parameters interact with eutrophication and algal blooms. However, there are few studies on the spatial–temporal characteristics of water parameters in the Chaohu Lake Basin. To assess the water quality of Chaohu Lake and its seven surrounding rivers, 132 samples from 33 sites were collected seasonally from September 2019 to July 2020, and 14 physicochemical parameters were detected. Our results showed that urban rivers had the highest nutrients, chemical oxygen demand (CODMn, 6.30 ± 0.80 mg/L), five-day biological oxygen demand (BOD5, 4.51 ± 0.42 mg/L), and chlorophyll a concentration (Chl a, 54.88 ± 39.81 μg/L); forested rivers had higher water transparency (137.83 ± 18.52 cm), lowest nutrients, CODMn (4.02 ± 0.20 mg/L), BOD5 (1.42 ± 0.14 mg/L), and Chl a (7.18 ± 1.41 μg/L); and agricultural and mixed rivers intermediate. Generally, the water quality was “good” and “light-eutrophic” according to the water quality index and trophic level index. The water quality order from good to worst in the season was spring > autumn and summer > winter. These results implied that urban rivers are still the main source of eutrophic nutrients in Chaohu Lake, and the control of urban pollutants is still the core of water quality management in Chaohu Lake.