李学先,吴攀,查学芳,何守阳,吴琳娜,韩志伟.基于水化学及稳定同位素的岩溶山区城镇水体硝酸盐来源示踪[J].环境科学学报,2021,41(4):1428-1439
基于水化学及稳定同位素的岩溶山区城镇水体硝酸盐来源示踪
- Tracing nitrate sources in urban waters of Karst mountainous area using hydrochemistry and stable isotope
- 基金项目：国家自然科学基金项目（No.41501018，41763019）；贵州省地质勘查基金项目（黔国土资地环函[2014]23）；贵州省人才基地项目（No.RCJD2018-21）
- 吴攀
- 2. 贵州大学资源与环境工程学院, 贵阳 550025;3. 喀斯特地质资源与环境教育部重点实验室, 贵阳 550025
- 查学芳
- 喀斯特地质资源与环境教育部重点实验室, 贵阳 550025
- 何守阳
- 喀斯特地质资源与环境教育部重点实验室, 贵阳 550025
- 吴琳娜
- 贵州大学资源与环境工程学院, 贵阳 550025
- 韩志伟
- 2. 贵州大学资源与环境工程学院, 贵阳 550025;3. 喀斯特地质资源与环境教育部重点实验室, 贵阳 550025
- 摘要：由于岩溶水文系统的地球化学敏感性和脆弱性，岩溶地下水NO3-污染已成为世界范围普遍存在的环境问题，而岩溶山区地下水硝酸盐来源解析对于保障区域供水安全和人体健康具有重要意义.因此，本文选取贵州中部典型岩溶山区城镇主要供水流域地表水和地下水为研究对象，基于土地利用类型，联合水化学分析及δ15N-NO3- 、δ18O-NO3-示踪技术对水体硝酸盐分布特征、来源贡献及迁移转化过程进行研究.结果表明，研究区水体溶解性无机氮以硝态氮为主，水体NO3-含量及分布与区域土地利用方式密切相关，硝酸盐污染主要集中于住宅用地和耕地 &林地区岩溶地下水中.水体NO3-主要来源于与农业活动和城镇化建设有关的土壤有机氮、化肥及粪便污水，水体氮循环主导过程为硝化作用，反硝化作用基本不存在.稳定同位素模型（SIAR）分析结果显示，区域水体硝酸盐主要受当地农业活动及城镇化过程影响，其中，土壤有机氮、化肥及粪便污水对地表水硝酸盐的贡献率分别为50.24%、27.97%和24.58%，对地下水硝酸盐的贡献率分别为54.58%、24.58%和20.15%，大气降水来源贡献率较低.
- Abstract：Nitrate (NO3-) contamination in Karst aquifer system has become a worldwide environmental problem.Identification sources of nitrate in Karst groundwater is of great significance for ensuring regional water security and human health.Both surface water and groundwater samples in typical Karst mountainous areas in Central Guizhou were collected.These samples were analyzed by hydrochemistry,environmental isotope tracer technique(δ15N-NO3- and δ18O-NO3-),combing with land-use type analysis to identify distribution,potential sources,contributions,transportation and transformation of nitrate.The results showed that dissolved inorganic nitrogen in surface water and groundwater were dominated as nitrate nitrogen.The concentration and distribution of NO3- in surface water and groundwater were significantly correlated to regional land-use types.Nitrate pollution is mainly occurred in Karst groundwater in residential land and cultivated land & forest areas.NO3- in surface water and groundwater was mainly derived from soil organic nitrogen,chemical fertilizers and manure/sewage related to agricultural activities and urbanization.The nitrogen cycle in surface water and groundwater was nitrification,while denitrification was not significant.The results from stable isotope model (SIAR) analysis showed that nitrate in surface water and groundwater mainly came from agricultural activities related to soil organic nitrogen and fertilizer,followed by manure and sewage related to urban activities.The contributions from soil organic nitrogen,fertilizer and manure and sewage to nitrate were 50.24%,27.97% and 24.58% in surface water and 54.58%,24.58% and 20.15% in groundwater,respectively.The rate of contribution from atmospheric precipitation to nitrate was relatively low.
