中文摘要：

工农业生产的迅速发展使地下水硝酸盐氮（NO3^-—N）污染成为世界性的环境问题。地下水中硝酸盐的来源研究在水文地质结构特殊的西南岩溶地区就显得尤为重要。稳定氮同位素和氧同位素在地下水硝酸盐的来源示踪研究中有着广泛的应用。本研究选取岩溶地区典型地下河——广西桂林寨底地下河为研究对象,通过氮氧同位素数据,判断寨底地下河硝酸盐来源是以动物粪便为主的农家肥,为该区地下水的保护和利用提供科学依据。

英文摘要：

Nitrate（NO3^-） contamination of groundwater is a crucial environmental problem in many regions of the world,which results from intensive agricultural activities,industrialization and urbanization.Knowledge of the sources of NO3^- contamination in groundwater is important for drinking water protection,especially for sensitive karst aquifers in southwest China.δ^15N and δ^18O data of NO3^- have been frequently used to identify NO3^- sources in groundwater.In this paper a typical subterranean river in karst regions,Zhaidi subterranean stream and other fives were investigated in Zhaidi basin.Based on water hydrochemical data,δ^15N and δ^18O data of NO3^- provide evidence for the source of dominant NO3^- in Zhaidi subterranean river,which is mainly from farmyard manure.