Zhao Ran, Han Zhi-Wei, Shen Chun-Hua, Zhang Shui, Tu Han, Guo Yong-Li
College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, China.
Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guiyang 550025, China.
Huan Jing Ke Xue. 2020 Jun 8;41(6):2664-2670. doi: 10.13227/j.hjkx.201911046.
Underground rivers are an important source of groundwater in karst area. Recently, nitrate pollution of underground rivers has become a serious issue. To identify the sources of nitrate in Guancun typical karst underground river basin, stable isotope techniques (N-NO, O-NO, and O-HO) were applied in this study. The contribution rates of different nitrate sources in groundwater were quantitatively identified based on the stable isotope analysis in R (SIAR) model, and the influence of land use type on nitrate distribution and source in watershed water was clarified. The results showed that ① nitrate mainly came from fertilizers, soil organic nitrogen, and manure/sewage based to the isotopic composition of nitrate nitrogen and oxygen isotopes. It was revealed that non-point sources significantly contributed to nitrate in waters of the Guancun underground river basin. ② Nitrification dominated the formation process of nitrate in groundwater, and the initial values of nitrogen and oxygen isotopes were not affected by fractionation. ③ Based on SIAR, the contribution of different sources to nitrate in water in the basin varied seasonally, and the contributions of fertilizer, soil organic nitrogen, and manure/sewage to nitrate were 57.07%, 34.06%, and 8.87% in the wet season and 34.14%, 33.02%, and 32.84% in the dry season, respectively. Overall, the present study quantitatively evaluated the temporal variations of nitrate sources in a typical karst groundwater river basin and provided a theoretical foundation for prevention and control management of non-point source pollution and watershed management in karst areas.
地下河是岩溶地区地下水的重要来源。近年来，地下河的硝酸盐污染已成为一个严重问题。为了识别官村典型岩溶地下河流域硝酸盐的来源，本研究应用了稳定同位素技术（N-NO、O-NO和O-HO）。基于R语言中的稳定同位素分析（SIAR）模型，定量识别了地下水中不同硝酸盐来源的贡献率，并阐明了土地利用类型对流域水体中硝酸盐分布和来源的影响。结果表明：① 根据硝酸盐氮和氧同位素的组成，硝酸盐主要来自化肥、土壤有机氮和粪便/污水。研究发现，非点源对官村地下河流域水体中的硝酸盐贡献显著。② 硝化作用主导了地下水中硝酸盐的形成过程，氮和氧同位素的初始值不受分馏作用的影响。③ 基于SIAR模型，流域内不同来源对水体中硝酸盐的贡献随季节变化，雨季化肥、土壤有机氮和粪便/污水对硝酸盐的贡献率分别为57.07%、34.06%和8.87%，旱季分别为34.14%、33.02%和32.84%。总体而言，本研究定量评估了典型岩溶地下水流域硝酸盐来源的时间变化，为岩溶地区非点源污染防治管理和流域管理提供了理论基础。
