Spatiotemporal Distribution Characteristics and Influencing Factors of Nitrogen and Phosphorus Concentrations in the Taihu Basin

ABSTRACT

Nitrogen and phosphorus are key drivers of the lake eutrophication, whose spatiotemporal distribution characteristics and influencing factors are critical to the management of the aquatic environment. Taihu Basin constitutes a focal area within the Yangtze River Economic Belt, and its eutrophication control holds significant guiding implications for China. In this study, we accurately identified the distribution patterns of total nitrogen (TN) and total phosphorus (TP) in time scales and spatial differences by analyzing monthly monitoring data from 80 surface water sections in the Taihu Basin from June 2021 to March 2024. Lindeman–Merenda–Gold model and Pearson's correlation analysis revealed the correlation and relative contribution of the environmental factors to TN and TP and the decisive factors of TN and TP, respectively. The results showed that from 2021 to 2023, TN and TP concentrations in the Taihu Basin during summer exhibited an initial decline followed by an upward trend. In winter, TN showed an initial increase followed by a decrease, whereas TP demonstrated a declining trend. Spatially, TN and TP concentrations peaked in Zhejiang and Shanghai, respectively, whereas both were lowest in Jiangsu. Six environmental factors were associated with TN and TP. TN had the highest association with ammonia nitrogen (NH ₃ ‐N) (0.388), and TP had the highest correlation with permanganate index (COD _Mn ) (0.485). Dissolved oxygen (DO), pH, and NH ₃ ‐N were the dominant driving factors for the seasonal variation of TN, whereas COD _Mn , DO, and NH ₃ ‐N significantly affected the seasonal variation of TP. These findings provide a scientific basis and valuable insights for targeted water environment management in the Taihu Basin.