关键词: 硝酸盐, 空间变异, 因子分析, 地统计分析, 地下水, 川中红层区

Abstract: In order to verify the pollution distribution and influencing factors of nitrate in groundwater in agricultural irrigation areas in central Sichuan red layer basin, a typical agricultural area in Jianyang city is selected as the study area. Spatial variability of nitrate pollution in groundwater are analyzed by the model of variogram and the geostatistics of ArcGIS. The influential factors of nitrate pollution are analyzed by factor analysis method. The results show that spherical model is the optimal model for interpolation analysis. The main parameters (the nugget, sill and nugget effect are 0.067, 0.736 and 0.091 respectively) show a strong spatial self-correlation of nitrate distribution. Most of the area suffers seriously nitrate pollution, and the polluted area accounts for about 91.8% of the total area. Agricultural activities and lithology characteristic of vadose zone promote the increase of nitrate in groundwater. The larger groundwater hydraulic gradient and strong runoff in the aquifers on the both sides of the Jinji River in the central study area, are unfavorable for the accumulation of pollutants, resulting in significantly lower nitrate content. Factor analysis shows that the nitrate content in groundwater is mainly controlled by stratigraphic lithology, topography, pH value and human activities, etc.

Key words: nitrate, spatial variation, factor analysis, geostatistical analysis, groundwater, red layer of central Sichuan basin