基于输出系数模型的清水河上游农业非点源污染负荷估算

结合调查资料和GIS技术，采用Johnes经典输出系数模型估算2000、2005、2010、2015年清水河上游流域总氮（TN）、总磷（TP）农业非点源污染负荷，并分析其时空变化特征和污染来源。结果表明，四个时期TN、TP的污染输出负荷均呈明显的下降趋势，且前者是后者的9.2~9.8倍；不同污染源类型对TN、TP负荷贡献率的影响规律相似，且土地利用是最关键的影响因素，表现为耕地>草地>林地。从空间变化趋势上，TN、TP的污染负荷强度分布特征相似：整体分布不均，高负荷区集中分布在清水河支流水系两岸坡度较小的平原和丘陵区，低负荷区主要分布在耕地较少的水源涵养区，且TN的负荷强度是TP的10倍左右。分别从土地利用、禽畜养殖和农村生活等角度分析其污染来源，结果表明耕地，尤其是蔬菜等经济作物种植是农业非点源污染的主要来源，禽畜养殖及居民生活是非点源污染的重要组成部分。

Estimation of Pollution Loads from Agricultural Non-point Sources in the Upstream of Qingshui River Based on Export Coefficient Models

Combined with survey data and GIS technology, Johnes classic export coefficient models were used to estimate the agricultural non-point source pollution loads of TN and TP in the upstream of Qingshui river in 2000, 2005, 2010 and 2015, and its temporal and spatial variation characteristics and pollution sources were analyzed.The results showed that the export loads of TN and TP in the four periods decreased significantly, and the former was 9.2~9.8 times higher than the latter.The influence of different pollution source types on the contribution rates of TN and TP loads was similar, and land use was the most critical factor, which was shown as cultivated land > grass land > forest land.From the spatial change trend, the distribution characteristics of TN and TP pollution loads intensity were similar, and the overall distribution was uneven. The high loads areas were concentrated in the plain and hilly areas with small slope on both sides of the Qingshui River tributary system, while the low loads areas were mainly distributed in the water conservation areas with less cultivated land, and the TN loads intensity is about 10 times of TP.Analyzed the pollution sources from the perspectives of land use,livestock breeding and rural life,the results showed that cultivated land, especially economic crops such as vegetables, was the main source of agricultural non-point source pollution, and livestock breeding and residents'' life were the important components of non-point source pollution.