桂林峰林平原区岩溶含水层氮污染空间分布特征

为确定桂林东区岩溶含水层氮污染特征,依据地层结构及土地利用状况,选择桂林东区27个地表水与地下水采样点进行取样分析. 结果显示:桂林东区地下水NO₃--N污染较为严重,ρ(NO₃--N)平均值(以N计,下同)为9.15mg/L,濒临世界卫生组织的地下水饮用标准界限(10mg/L)；ρ(NH₄+-N)基本未检出,ρ(NO₂--N)较低且NO₂--N主要存在于地表水中,NH₄+-N和NO₂--N都不是该区地下水中氮的主要存在形式. 不同土地利用类型的区域ρ(NO₃--N)水平(0.088~46.700mg/L)不同. 居民区生活污水和牲畜粪肥是浅层地下水的主要NO₃--N污染源,种植蔬菜施用的有机肥则是农业区的NO₃--N污染源. 此外,受水文地质条件的影响,在研究区地下水流场内沿地下水流方向ρ(NO₃--N)呈逐渐升高的趋势. 

Spatial Distribution of Nitrogen Contamination in Karst Aquifer in Guilin Peak Forest Plain

To determine the characteristics of nitrogen contamination in karst aquifer in the east Guilin, samples of the surface and groundwater were sampled according to the stratigraphic structure and patterns of the land use. The results showed that the groundwater in the eastern Guilin was contaminated by nitrate. The average concentration of NO₃--N was 9.15mg/L, which was on the edge of unsuitable for drinking water according to the National Quality Standard of Groundwater (10mg/L). NH₄+-N was basically not detected, and the concentration of NO₂--N was also very low, which mainly existed in the surface water. These two forms of nitrogen were not the main types of the underground water in this area. Different patterns of the land use had different NO₃--N levels ranging from 0.088to 46.700mg/L. The main source of NO₃--N pollution in the shallow groundwater was sewage and cattle manure in the residential area. Organic fertilizer used for vegetable planting was the source of NO₃--N pollution in the agricultural area. In addition, influenced by the hydrogeology condition, the concentration of NO₃--N had a rising trend with the flow direction of the groundwater in this area.