National-scale evaluation of phosphorus emissions and the related water-quality risk hotspots accompanied by increased agricultural production

Abstract

Water quality and food security are two key themes of human existence, and the critical question we are facing is how to achieve safe water quality without decreasing agricultural production. In this study, an assessment framework has been developed by scaling emission factors from 232 monitoring plots to large scales, as well as by introducing two new concepts, agriculture-water body transportation potential (AWP) and crop-environment partition coefficient (C/E) values. Then, a first assessment of national-scale agricultural non-point-source phosphorus (NPS-P) emissions and the related water-quality risk during Chinese agricultural miracle period were provided at high resolution (1 km*1 km). Finally, a joint analysis of the national NPS-P emissions and crop production hotspots was conducted in support of sustainable development on a national scale. The results indicated that NPS-P emissions from agricultural fertilizer application in China have increased by 31% from 2004 to 2013, but high- and extremely-high-risk areas of agricultural pollution have decreased by 38%. The Lianghu Plain, North China Plain, and Yangtze River Delta were identified as hotspots of high crop yields, while an improvement in nutrient utilization in terms of increasing C/E values in these regions could also be observed.