利用氮氧同位素示踪吉水县地下水中硝酸盐污染源

Tracing nitrate pollution sources in groundwater in Jishui County using nitrogen and oxygen isotopes

地下水的硝酸盐污染问题日益得到重视。本次共采集地下水样品39组,其中水源地水样16组,民井水样23组,利用氮氧同位素示踪吉水县地下水中硝酸盐污染来源。研究得出:水源地的氮氧同位素特征值δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)变化范围分别为6.33‰~26.60‰、-0.68‰~19.90‰,平均值分别为12.38‰、7.52‰;民井水体的氮氧同位素特征值δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)变化范围分别为2.75‰~31.01‰、3.^(18)‰~16.94‰,平均值分别为14.29‰和8.75‰。利用混合水源同位素判识模型对研究区内地下水中的硝酸盐来源贡献率进行计算:水源地主要污染源为粪肥和污水,平均贡献率为47.72%;水源地周边民井主要污染源为粪肥和污水,平均贡献率为58.35%;工业园区周边民井主要污染源为降水和肥料,平均贡献率为39.54%;垃圾填埋场周边民井主要污染源为粪肥和污水,平均贡献率为96.92%。

Nitrate pollution in groundwater has been paid more and more attention.A total of 39 groups of groundwater samples were collected in this project,including 16 groups of water samples from water source and 23 groups of civil well water samples.Nitrogen and oxygen isotopes were used to trace the sources of nitrate pollution in groundwater of Jishui County.The results showed that the characteristic value of nitrogen and oxygen isotope in water sourceδ^(15)N-NO_(3)^(-)was in range of 6.33‰~26.60‰,whileδ^(18)O-NO_(3)^(-)in range of-0.68‰~19.90‰,and the average value is 12.38‰and 7.52‰respectively.The characteristic value of nitrogen and oxygen isotope of civil wellδ^(15)N-NO_(3)^(-)was in range of 2.75‰~31.01‰,whileδ^(18)O-NO_(3)^(-)in range of 3.^(18)‰~16.94‰,and the average value is 14.29‰and 8.75‰respectively.The contribution rate of nitrate sources in the study area was calculated by using the isotope identification model of mixed water sources.The main pollution sources of water sources are manure and sewage,with the average contribution rate of 47.72%.The main pollution sources of the civilian well water near the water source are manure and sewage,with the average contribution rate of 58.35%.The main pollution sources of civilian well water near the industrial park are precipitation and fertilizer,with the average contribution rate of 39.54%.The main pollution sources of civilian well water near the landfill are manure and sewage,with the average contribution rate of 96.92%.