Socioeconomic drivers and future projections of anthropogenic nitrogen and phosphorus inputs in the Pearl River Basin of China

Excessive net anthropogenic nitrogen and phosphorus inputs (NANI and NAPI) are key drivers of aquatic ecosystem degradation, leading to eutrophication and water quality deterioration. In this study, we aim to improve our understanding spatiotemporal distribution patterns, the associated driving factors and potential mitigation strategies of NANI and NAPI. To this end, we developed an integrated modeling system by coupling the NANI/NAPI framework with a system dynamics model. We applied this linked model system to the Pearl River as an illustrative example. The NANI and NAPI in the Pearl River basin showed large spatial variability. Our results indicated that the NANI and NAPI increased by 25.7 % and 67.6 % and peaked in 2015 and 2017, respectively. Under future climate change scenarios, NANI in the Pearl River Basin is projected to decrease by 2.9 % (SSP1) or increase by 24.7 % (SSP3) by 2050, while NAPI will rise by 6.9 % (SSP1) or 66.5 % (SSP3), respectively. Our findings highlight the urgency of region-specific interventions—promoting dietary shifts and sustainable agriculture in urbanized areas, versus optimizing fertilizer use in rural regions. This framework offers actionable insights for nutrient management in rapidly developing watersheds worldwide.