湖北省三峡库区1991—2014年农业非点源氮磷污染负荷分析

为研究湖北省三峡库区农业非点源氮磷污染负荷的时空分布特征，分析主要农业污染源和重点控制区域，运用改进的输出系数模型结合入河系数对研究区1991—2014年的不同农业源（农村生活、畜禽养殖和农田种植）和不同地区（夷陵、秭归、兴山、巴东）总氮总磷负荷量、排放强度进行估算，并对时空分布特征进行了分析。结果表明，1991—2014年湖北省三峡库区农业非点源污染总氮、总磷年均负荷量分别为2 132.10、222.64 t·a^-1，年均排放强度分别为1.85、0.19 kg·hm^-2·a^-1。2006年以前，总氮、总磷负荷较低，而后缓慢增加。相比于1991年，2014年总氮年负荷量降低了4.22%，总磷年负荷量增加了12.30%。从各类污染源贡献来看，旱地和乡村人口是总氮的主要贡献源，旱地和猪的养殖是总磷的主要贡献源。从氮磷负荷空间分布看，巴东县的总氮、总磷负荷最高，夷陵次之。从排放强度的空间分布看，巴东县的排放强度最高，其次是秭归。研究表明，农田种植和畜禽养殖是总氮、总磷负荷的主要贡献源，巴东县是农业非点源防治的重点控制区域，湖北省三峡库区的农业非点源污染防治工作仍需努力。

Analysis of nitrogen and phosphorus pollution loads from agricultural non-point sources in the Three Gorges Reservoir of Hubei Province from 1991 to 2014

To study the temporal and spatial distribution characteristics of nitrogen and phosphorus pollution loads from agricultural non-point sources and analyze the main agricultural pollution sources and key control regions in the Three Gorges Reservoir Area(TGRA) of Hubei Province, the improved export coefficient model combined with the loss coefficient method was applied. This was based on agricultural data from 1991 to 2014 to estimate total nitrogen(TN) and total phosphorus(TP) pollution loads and emission intensities from different sources(rural life, livestock breeding, and planting) and different districts(Yiling, Zigui, Xingshan, and Badong). Spatial and temporal distribution characteristics were analyzed at the same time. The results showed that from 1991 to 2014, the annual average TN pollution load was 2 132.10 t·a^-1, the annual average TP pollution load was 222.64 t·a^-1, and the annual average TN emission intensities was 1.85 kg·hm^-2·a^-1, the annual average TP emission intensities was 0.19 kg·hm^-2·a^-1. Before 2006, TN and TP pollution loads reduced year by year, and then slowly increased. Compared with 1991, the annual TN pollution loads in 2014 decreased by 4.22% and the annual TP pollution loads increased by 12.30%. Dry land and rural population were the main sources of TN pollution loads, while dry land and pig raising were the main sources of TP pollution loads. Badong was the major source of TN and TP pollution loads spatially, followed by Yiling. Based on the spatial distribution of emission intensity, Badong had the highest emission intensity, followed by Zigui. The study found that farmland planting and livestock breeding were the main sources of TN and TP pollution loads, Badong was the key control region of agricultural non-point source pollution, and prevention and control efforts for agricultural non-point source pollution at TGRA of Hubei Province are still required.