Water quality variation and its conditioning factors in the Three Gorges Reservoir, China

The variation of water quality has been an issue of concern since the impoundment of the Three Gorges Reservoir (TGR). In this study, water samples from the TGR were collected in July and November 2015 and in May and July 2016 to reveal the variations of water quality and its key conditioning factors. The results showed that the concentrations of major ions, nutrients and heavy metals in the TGR's water body exhibited heterogeneous variations. Especially, the hotspot for major ions and heavy metals emerged at Chongqing downtown, and a decreasing trend from Chongqing toward the TGR dam was spatially observed. The heterogeneous variation of hydrochemistry in the TGR revealed the integrated influences of natural processes and human activities. Especially, the intense rainfall in the spring and early summer of 2016 promoted the transport of pollutants to the TGR, and further magnified the influence of large cities on the spatial variations of the hydrochemistry in the TGR. This study will give more insights into the change of water quality in large reservoirs in the context of the intense rainfall and the human activities.

Automated summary

The study revealed heterogeneous variations in major ions, nutrients, and heavy metals concentrations in the Three Gorges Reservoir, with Chongqing downtown identified as a hotspot for pollutants. The findings also showed a decreasing trend in pollution levels from Chongqing towards the reservoir dam. The study highlighted the combined influences of natural processes, intense rainfall, and human activities on water quality variations in large reservoirs like the Three Gorges Reservoir.