Water contamination and corresponding influencing factors: the sub-region of the Taihu lake basin, China

In the context of the extensive concern about the water contamination issue in China, especially in the Taihu lake basin of the Yangtze delta, this study has investigated the water quality status, identified the priority pollutants, analysed the environmental and artificial factors, and proposed targeted measures in the Wujiang district via a self-designed conceptual framework. Four representative rivers were selected as the research objects, namely the Wufanggang Canal (WFG), the Xidagang River (XDG), the Datang River (DDT), and the Zixingtang River (ZXT), which are distributed in diverse locations in the Wujiang district of the Taihu lake basin. A single factor index (SFI) approach was applied to detect the water quality and pollution indices. The relationships between the priority pollution factors, i.e. ammonia nitrogen (AN) and total phosphorus (TP), and their seasonal and temperature variations were examined through the regression analysis using the SPSS software. The overall results demonstrated that AN and TP were the predominant constraints affecting water quality, which aligns with previous studies in this region. WFG was the most polluted river with a significant positive correlation between the concentration of AN and TP (P≤0.01). Seasonally, there were certain degrees of positive correlation between the concentration of AN and TP in spring (P<0.1) and summer (P<0.01). As for temperature, all three water bodies, except WFG, exhibited certain degrees of correlation for both AN and TP. Based on on-site visits to the most polluted WFG, it was found that the major cause of the severe pollution is non-point source pollution (NPS) from upstream and surrounding industrial and agricultural land uses and human activities. The study provides a scientific basis for further understanding the relationship between pollutant concentrations and environmental and artificial factors, and contributes to integrated water environment management strategies of such water bodies, especially in the Wujiang district and the Taihu lake basin. The established research framework could also be applied in other regions and watersheds to assess the contamination status and propose targeted measures.