Abstract:

Based on the monthly monitoring of the northern of the Qingmuguan undergroundwater from March,2008 to October,2008,and the monthly monitoring of the southern of the Qingmuguan groundwater from June,2010 to October,2010,using hydrochemical and 15N isotope techniques,variations of nitratenitrogen and its possible sources were investigated.The results showed that the nitrate concentrations were 2035 mg/L and 5077 mg/L at the outlet of the north and south underground river,and were 320 mg/L and 0842 mg/L at the inlet of the river.The outlet of the two parts were all 6 times more than the inlet of them. In addition,through analyzing the spatial distribution of δ15N in the whole underground river basin,it could be concluded that the southern of the underground river had high NO-3δ15N,and changed significantly.The maximum value(37825‰)appeared in the Dingjia cave sampling point on September 21.The nitrate source might be waste and sewage.The northern of the underground river had low NO-3δ15N and a small rangeability.δ^15N data were all bellow 10‰.The source of the nitrate were soil organic nitrogen and nitrogen in agriculture