Net anthropogenic nitrogen and phosphorus inputs in the Yangtze River economic belt: spatiotemporal dynamics, attribution analysis, and diversity management

摘要

Excess production of nitrogen (N) and phosphorus (P) by human activities poses a severe threat to water quality. Therefore, quantitative evaluations of regional nutrient inputs and contributions from the main driving factors are necessary. This study aims to identify the spatiotemporal heterogeneity of the net anthropogenic N and P inputs (NANI and NAPI) in China's Yangtze River economic belt and explore the environmental effects, influencing factors, and diversity management through the NANI and NAPI model and statistical models. The results reveal that (1) NANI and NAPI first increase and then decrease during 2000-2017, with average values of 7,292 kg N km(-2) yr(-1) and 2,306 kg P km(-2) yr(-1), respectively; (2) the spatial variation of NANI and NAPI exhibits a decreasing trend from east to west and north to south, which is strongly related to the distribution of urban agglomerations and land-use patterns; (3) the higher net anthropogenic inputs of N and P are associated with the higher N and P concentrations in rivers and lakes, which show the spatial pattern of a banded distribution and local concentration; and (4) changes in economic factors contribute the most to the changes in NANI and NAPI, with average contributions of 74.1% and 74.3%, respectively, followed by land-use factors, with average values of 19.5% and 19.3%, respectively; social factors are less impactful to changes in NANI and NAPI (6.4% for each). Based on results, a nutrient diversity management mechanism was constructed, which provides a scientific reference for regional environmental protection and policy formulation.