中文摘要：

以长江中下游地区所处的六省一市为研究对象,通过对80个市级行政区化肥施用情况的调研,估算了农田化肥氮磷地表径流流失量,在耦合农业化肥流失量、降雨和河网密度三种因素的基础上,提出了农田化肥氮磷污染风险分级方法并初步识别了重点区域。结果表明,近20年来,其化肥施用量呈现上升趋势,氮磷地表流失量较高的区域主要集中于湖南省,氮磷流失强度的平均值分别为2.41、0.61 kg·hm-2·a-1。湖南省为六省一市中农田化肥氮磷污染的高风险区,上海市为低风险区,其他五省则以中、低污染风险为主。研究结果有助于实现对农田面源污染的风险防范,推动我国农业面源污染防控的优化升级。

英文摘要：

Nitrogen and phosphorus loss in farmland fertilizer is the main cause of environmental water pollution. Using six provinces and one city in the middle and lower reaches of the Yangtze River as a study area, and by investigating on the data of fertilizer of 80 municipals,we estimated the loss of nitrogen and phosphorus in surface runoff from farmland fertilizer. Based on the combination of three factors, namely fertilizer loss, rainfall, and drainage density, we put forward a scheme to classify the pollution risk from fertilizer nitrogen and phosphorus,and identified the key areas of concern preliminarily. The results show that fertilizer application has increased during the past 20 years, and areas with high nitrogen loss and phosphorus surface runoff are concentrated in Hunan Province. The average nitrogen and phosphorus loss intensities were 2.41 and 0.61 kg·hm-2·a-1, respectively. The zone with a high risk of pollution was Hunan Province, Shanghai City was the low risk zone, and the other five provinces were dominantly middle-and low-risk areas. These results are beneficial to preventing risk from agricultural non-point source pollution and promoting the optimization of control measures in China.