基于水化学和稳定同位素的白洋淀流域地表水和地下水硝酸盐来源

Source of Nitrate in Surface Water and Shallow Groundwater Around Baiyangdian Lake Area Based on Hydrochemical and Stable Isotopes

为探究白洋淀流域生活污水河附近地表水和地下水硝酸盐来源,于2014年7月沿着生活污水纳污河——府河采集地表水和地下水.通过分析水化学和氢氧同位素(δ~2H、δ^(18)O)明确地表水和地下水转化关系,并通过硝酸盐氮(δ^(15)N)同位素确定硝酸盐来源.结果表明,河水来源于城市和农村生活污水,同时受蒸发作用影响.浅层地下水受府河、白洋淀和太行山山区地下水侧向补给.浅层地下水硝酸盐超标(世界卫生组织)率为16.7%.受水体自净能力的影响,府河上游硝酸盐浓度大于下游.受区域水流方向的影响,南岸浅层地下水硝酸盐浓度大于北岸.近河和近淀区域浅层地下水硝酸盐主要来自于地表水.此外,土壤、化肥及其点源污染也是地下水硝酸盐的主要来源.城市和乡村居民生活及农业生产活动影响区域地表水和地下水硝酸盐.

In order to study the source of nitrate in surface water and groundwater near a domestic sewage discharge river in the Baiyangdian watershed,including the Fuhe River and Baiyangdian Lake,shallow groundwater and deep groundwater samples were collected in July 2014.Water chemistry and stable isotopes（δ2H and δ（18）O） were used to study the relationship between the surface water and groundwater.δ（15）N was used to explore the source of nitrate.The results show that urban and rural domestic sewage discharge to Fuhe River and then experience evaporation.Shallow groundwater is affected by the Fuhe River,Baiyangdian Lake,and lateral recharge from groundwater in the Taihang Mountain area.There are 16.7% of shallow groundwater samples exceeds the NO3- threshold for drinking water according to the World Health Organization standard.Due to the effect of self-purification capacity,the NO3- mass concentration in the Fuhe River is higher in the upstream area than in the downstream area.Due the regional water flow from northwest to southeast,the NO3- mass concentration in the shallow groundwater is higher in the south bank area than in north bank area.The shallow groundwater near the Fuhe River and Baiyangdian Lake is recharged by surface water.In addition,soil,fertilizer,and point sources are also major sources for groundwater nitrate.Urban and rural residential living and agricultural production activities are the main reasons for surface water and groundwater nitrate.