运用氮、氧同位素技术判别常州地区地下水氮污染源

Analyses of pollution source of nitrogen in groundwater with δ^(15)N-NO_3 and δ^(18)O-NO_3 in Changzhou

本文运用氮、氧同位素技术对常州地区地下水氮的污染来源进行了研究。结果表明:潜水和微承压水中NO3-含量高,平均含量为38.32 mg/L,δ15N为4.818‰~32.834‰,δ18O为12.502‰~20.757‰,反映了多数潜水和微承压水受到了厩肥和污水的污染;中深层承压水(第1承压水、第2承压水、第3承压水)中NO3-含量低,NO3-平均含量为0.52 mg/L,未受到氮污染,δ15N为2.163‰~6.208‰,δ18O为17.051‰~23.201‰,NO3-应主要来源于早期形成时的大气降水。

δ^15N-NO3 and δ^18O - NO3 are direct indicators for nitrogen pollution source. Nitrate and the δ^15 N-NO3 , δ^18O-NO3 in groundwater have been sampled and analyzed in Changzhou. The result shows that in the shallow aquifers （phreatic and semi- confined aquifers） , the mean value of nitrate concentration is 38.32 mg/l, δ^15N-NO3 ranges from 4.818‰ to 32.834‰, and δ^18O ranges from 12.502‰ to 20.757‰, implying that the shallow groundwater suffered pollution from barnyard manure and sewage. While in groundwater in deep aquifers （1,2,3 confined aquifers）, the mean value of nitrate concentration is 0.52 mg/l, much lower than that in the shallow aquifer, and δ^15N and δ^18O with values of 2.163‰- 6.208‰,17.051‰- 23.201‰ , respectively. Groundwater in the area seldom suffered pollution from nitrogen, and nitrogen mainly comes from rainwater in the geological history.