The Characteristics of Net Anthropogenic Nitrogen and Phosphorus Inputs (NANI/NAPI) and TN/TP Export Fluxes in the Guangdong Section of the Pearl River (Zhujiang) Basin

Human activities have greatly influenced the inputs and cycling pathways of nitrogen (N) and phosphorus (P), causing dramatic environmental problems in the Pearl River Basin. In this study, the characteristics of net anthropogenic nitrogen and phosphorus inputs (NANI/NAPI) were analyzed in the Guangdong section of the Pearl River Basin from 2016 to 2020. NANI showed a very slight decrease trend from (1.51 ± 0.09) × 104 to (1.36 ± 0.08) × 104 kg·N·km−2·yr−1, while the average intensity of NAPI was 3.8 × 103 kg·P·km−2·yr−1. Both NANI and NAPI intensities were at high levels, resulting in the serious deterioration of water quality in the Pearl River Basin. Fertilizer input was the most important component for the intensities of NANI and NAPI, accounting for 38–42% and 53–56%. However, in the Pearl River Delta, the major components of NANI and NAPI were the human and animal consumption (food/feed) inputs and non-food net phosphorus input. The input of NANI and NAPI should be controlled for different areas, based on the differing driving forces, to alleviate the deterioration of water quality. This study of NANI and NAPI in the Pearl River Basin is one of the important prerequisites for clarifying the input and water quality, providing support for further effective control of nitrogen and phosphorus pollution in the Pearl River.