Seasonal Water Quality Changes and the Eutrophication of Lake Yilong in Southwest China

Abstract

To better understand the seasonal variation characteristics and trend of water quality in Lake Yilong, we monitored water quality parameters and measured nutrients, including the water temperature (WT), Chlorophyll-a (Chl-a), dissolved oxygen (DO) and pH from September 2016 to May 2020, total nitrogen (TN) and total phosphorus (TP) from October 2016 to August 2018. The results showed that the lake water was well mixed, resulting in no significant thermal stratification. The DO content was decreased in the northwest part of the lake during September and October, resulting in a hypoxic condition. It also varied at different locations of the lake and showed a high heterogeneity and seasonal variability. The Chl-a concentration in Lake Yilong demonstrated seasonal and spatial changes. It was maximum at the center and southwest area of the lake in January. However, in the northwest part of the lake, the maximum value appeared in September and October. The content of TN in the rainy season increased by 75% compared with that in dry season and TP content show a downward trend (from 0.11 mg/L to 0.05 mg/L). The comprehensive nutrition index evaluation shows that the water quality of Lake Yilong in 2016 was middle eutrophic (TLI = 60.56), and that in 2017 (TLI = 56.05) and 2018 (TLI = 56.38) was weak eutrophic, showing that the nutritional status has improved. TN remained at a high level (2.15 ± 0.48 mg/L), water quality needs further improvement. Based on our monitoring and analysis, it is recommended that human activities in the watershed of the lake should be constrained and managed carefully to maintain the water quality of the lake and adopt effective water quality protection and ecological restoration strategies and measures to promote continuous improvement of water quality, for a sustainable social development.

Analysis of water quality and trophic status of reservoirs in Chuzhou City, China

“…The mechanism of its occurrence is mainly when the water body is enriched with excessive N and P nutrient salts, algae will rapidly multiply and form water bloom, which hinders the penetration of light, thus leading to the eutrophication of the water body. Meanwhile, TN and TP have historically been recognized as the main drivers of eutrophication (Havens & Walker, 2002; Sui et al, 2022); this is also consistent with the findings of this study. In summary, water quality in the three reservoirs is generally poor, and the TLI (Σ) does not show a sustained downward trend (Figures S4 and S5).…”

“…as the main drivers of eutrophication (Havens & Walker, 2002;Sui et al, 2022); this is also consistent with the findings of this study. In summary, water quality in the three reservoirs is generally poor, and the TLI (Σ) does not show a sustained downward trend (Figures S4 and S5).…”

“…It is well known that Chl‐a is an essential indicator for characterizing algae biovolume and measuring the degree of eutrophication. (Li, Wang, et al, 2021; Saluja & Garg, 2017; Sui et al, 2022). The TLI (Chl‐a) from May to September was higher than that of other months (Figures S7–S9), mainly because the summer temperature is suitable for phytoplankton growth and reproduction, which promotes the metabolic rate and cell division of phytoplankton, increases the productivity of phytoplankton and aggravates the eutrophication of the water body.…”

Ecological Risk Assessment of Heavy Metal (Pb, Cu) Contamination in Water, Sediment, and Polychaeta (<i>Neoleanira Tetragona</i>) from Coastal Areas Affected by Aquaculture, Urban Rivers, and Ports in South Sumatra

“…Water temperature values tend to be high in aquaculture areas. This is related to the infiltration of sunlight into the surface and deeper layers and the movement of water masses(Sui et al, 2022;Li et al, 2022). The distribution of polychaeta can be affected by changes in salinity in the estuary area, which will result in a decrease in the number of macrobenthos(Liu et al, 2023).…”

Semiarid Lakes of Southwestern Siberia as Sentinels of On-Going Climate Change: Hydrochemistry, the Carbon Cycle, and Modern Carbonate Mineral Formation

“…The lakes of group II and V are characterized by stronger fluctuations in pH, probably related to macrophytes that overgrow the water reservoir as known in other settings [53]. Nevertheless, overall variability of pH values, both within each group and in the entire sample set, was low (CV < 33%), which implies a homogeneity of acid-base conditions (Table A5).…”