基于输出系数法及土地利用方式识别的营养盐空间负荷解析—以十堰市为例

在过去的几十年里，我国氮肥和磷肥的施用量增长显著。然而，过量的营养物质也导致内陆和沿海水域水体富营养化问题。氮、磷营养盐的控制通常被认为是减少湖泊富营养化和蓝藻水华的重要组成部分。目前，准确识别营养物质的来源和定量分析过量营养物质浓度在空间上的表现仍需要特别关注。根据十堰市污染物统计及生态环境部门相关监测数据，通过输出系数法及土地利用方式识别，分析了氮、磷营养盐来源及其空间负荷分布。结果表明：十堰市总氮、总磷均主要来源于面源，占比分别为81.84%和80.08%，点源占比较小。其中总氮污染负荷主要来源于农田径流污染源，占45.72%，其次是干湿沉降污染源，占11.43%；总磷污染负荷也主要来源于农田径流污染源，占30.51%，其次是水土流失污染源，占22.28%。总氮入河负荷强度最高为22.71 t/km²，总磷入河负荷强度最高为5.22 t/km²。

Spatial nutrient load analysis based on output coefficient method and land use pattern identification:a case study of Shiyan City

The application rate of nitrogen and phosphate fertilizers has increased significantly in China over the past few decades. However, the over-dozed nutrients also lead to the serious problem of eutrophication in inland and coastal waters. The control of nitrogen and phosphorus nutrients is generally considered to be an important part of reducing lake eutrophication and cyanobacteria blooms. Currently, the accurate identification of nutrient sources and the quantitative deconstruction of the spatial representation of excess nutrient concentration still require special attention. Based on the statistical data of pollutants in Shiyan City and the relevant monitoring reports of eco-environmental protection departments, the source composition and spatial load distribution of nitrogen and phosphorus nutrients were analyzed by the output coefficient method and land use pattern identification. The results showed that total nitrogen and total phosphorus of Shiyan City were mainly from non-point sources, accounting for 81.84% and 80.08%, respectively, and point sources accounted for less. The total nitrogen pollution load mainly came from farmland runoff, accounting for 45.72% of the total, followed by dry and wet deposition pollution sources, accounting for 11.43% of the total. The total phosphorus pollution load also mainly came from farmland runoff, accounting for 30.51% of the total, followed by soil erosion, accounting for 22.28% of the total. The highest load intensity of total nitrogen into the river was 22.71 t/km2, and the highest load intensity of total phosphorus into the river was 5.22 t/km2.