Spatio-temporal heterogeneities in water quality and their potential drivers in Lake Chaohu (China) from 2001 to 2017

Damage to the water ecosystems and the deterioration of lake water resources may negatively affect the surface water resources, particularly, which of the daily drinking water supply of residents. Therefore, it is particularly important to study the spatio-temporal heterogeneity of water quality in large lakes. We analysed the data from six sampling sites in Lake Chaohu from 2001 to 2017 and eight sampling sites of the inflow rivers in 2001, 2009 and 2017. The six sampling sites were divided into SG I and SG II through cluster analysis, and the spatio-temporal changes of the water quality in the Lake Chaohu Basin were studied. The results indicated the following: All nutrient variables had relatively high concentrations in SG II except DO, while SG I had relatively high concentrations of only TN. Besides, the value of Chl a in each group is generally high. On the temporal scale, the changes in the water quality of the lake showed strong seasonality; the nutrient variable (TN, TP, NH4-N and CODMn) except DO in the inflow rivers is generally higher than that of the lake; the water quality of Lake Chaohu has improved during the study period, and it has also improved to a certain extent compared with that of the late 1980s. Fortunately, parts water quality parameters of Lake Chaohu have improved faster than that of the other four largest freshwater lakes in China. This research result has a certain guiding significance for the prevention and control of large lake water pollution.

Automated summary

The study reveals significant spatio-temporal heterogeneity in water quality of Lake Chaohu, with notable variation in nutrient distribution and changes at different sampling points. There is seasonal variability in the lake water quality, with nutrient concentrations generally higher in the inflow rivers compared to the lake water quality. Overall, there has been improvement in the water quality of Lake Chaohu during the study period.