摘要
利用多同位素(C、N和O)和水化学方法解析贵州八步地下河流域水体中硝酸盐(NO_(3)^(-))来源与转化过程,利用SIAR模型定量计算NO_(3)^(-)不同输入端的贡献比例.结果表明,研究区地下水NO_(3)^(-)污染严重,近38%的地下水样品NO_(3)^(-)超过饮用水限值.地下水的δ^(15)N-NO_(3)值介于2.3‰~30.33‰,均值9.68‰,δ^(18)O-NO_(3)值介于2.65‰~13.73‰,均值6.64‰,δ^(18)O-H_(2)O值介于-8.83‰~-7.37‰,均值-8.18‰.同位素组成(δ^(15)N-NO_(3)、δ^(18)O-NO_(3)和δ^(18)O-H_(2)O)指示硝化作用主导着流域内氮素循环.硝化作用产生的硝酸加速了碳酸盐岩溶解,导致地下水中δ^(13)CDIC与δ^(15)N-NO_(3)存在显著负相关性(P<0.001),说明δ^(13)CDIC与δ^(15)N-NO_(3)相结合是判断岩溶水中NO_(3)^(-)转化的有效手段.地下水和地表水中NO_(3)^(-)主要来源于土壤氮、粪肥污水和铵态氮肥料,其对地下水中NO_(3)^(-)贡献率分别为36.19%、33.71%和30.1%,对地表水贡献率分别为39.15%、36.08%和24.77%.岩溶流域内污水处理应同时去除污水中的NO_(3)^(-)和NH_(4)^(+),农业区应科学施肥,以有效降低地下水中NO_(3)^(-)的补给通量.
Multiple isotopes (C,N,and O) and hydrochemical data were used to trace the sources and fate of nitrate in ground and surface waters of the Babu subterranean stream watershed in Guizhou Province.The origin of nitrate in the water samples was also quantitatively analyzed by the SIAR model.Approximately 38%of the groundwater samples were not drinkable because the nitrate exceeded the drinking water standard,thereby indicating that the groundwater was seriously polluted by nitrate.The ranges ofδ^(15)N-NO_(3),δ^(18)O-NO_(3),andδ^(18)O-H_(2)O in groundwater were 2.30‰-30.33‰(mean of 9.68‰),2.65‰-13.73‰(mean of 6.64‰),and-8.83‰--7.37‰(mean of-8.18‰),respectively.Based on the stable isotopic compositions (δ^(15)N-NO_(3),δ^(18)O-NO_(3),andδ^(18)O-H_(2)O),nitrification was the dominant process in the basin.The nitric acid produced by nitrification promoted the dissolution of carbonate rocks,thereby leading to a significantly negative correlation (P<0.001) between the carbon isotope of dissolved inorganic carbon (δ^(13)CDIC) andδ^(15)N-NO_(3)and indicating thatδ^(13)CDIC,combined withδ^(15)N-NO_(3),is effective in exploring the fate of nitrate in karst groundwater.The nitrate in the ground and surface waters mainly originated from soil N,manure and sewage,and ammonium nitrogen fertilizer.The results of the SIAR model showed that the contributions of soil N,manure and sewage,and ammonium nitrogen fertilizer were 36.19%,33.71%,and 30.10%in groundwater,respectively,and 39.15%,36.08%,and 24.77%in surface water,respectively.Therefore,it would be more effective to reduce the nitrate recharge flux in groundwater by simultaneously removing nitrate and ammonium nitrogen during wastewater treatment and by adopting scientific fertilization technology in agricultural areas.
作者
任坤
潘晓东
梁嘉鹏
彭聪
曾洁
REN Kun;PAN Xiao-dong;LIANG Jia-peng;PENG Cong;ZENG Jie(Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,China;Key Laboratory of Karst Dynamics,Ministry of Natural Resources&Guangxi,Guilin 541004,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2021年第5期2268-2275,共8页
Environmental Science
基金
国家自然科学基金项目(41702278)
中国地质调查局地质调查项目(DD20190326)
广西岩溶动力学重点实验室项目(2018-242-Z01)
中国地质科学院基本科研业务费项目(2020018)。
关键词
硝酸盐
氮氧同位素
碳同位素
SIAR模型
来源解析
岩溶水
nitrate
nitrogen and oxygen isotopes
carbon isotope
SIAR model
sources identification
karst groundwater
