Wang Xihua, Liu Zejun, Xu Y Jun, Mao Boyang, Jia Shunqing, Wang Cong, Ji Xuming, Lv Qinya
College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Department of Earth and Environmental Sciences, University of Waterloo, ON N2L 3G1, Canada.
College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
Sci Total Environ. 2025 Jan 1;958:178134. doi: 10.1016/j.scitotenv.2024.178134. Epub 2024 Dec 17.
Tracing the source of nitrate is the key path to solve the problem of nitrogen pollution. However, the seasonal difference of nitrate sources in groundwater and surface water and its dynamic evolution process and mechanism in large fresh water lake area are still not clear. In this study, 126 water samples were collected from groundwater and surface water in China's largest fresh water lake (Poyang Lake) region from 2022 to 2023. Bayesian stable isotope mixing model, absolute principal component score-multiple linear regression, ion ratio coefficients and uncertainty index (UI) were used to investigate the nitrate sources variation in groundwater and surface water as well as its uncertainty in Poyang Lake area. Results showed that anthropogenic influence had significant influence on nitrate sources, which was mainly affected by chemical fertilizer (CF), soil nitrogen (SN) and manure and sewage input (M&S). Specifically, from 2022 to 2023, CF contributed 16.6 % to 32.4 %, SN contributed 26.0 % to 38.1 %, M&S contributed 26.5 % to 48.2 % to groundwater. CF contributed 38.8 % to 43.9 %, SN contributed 37.6 % to 40.6 %, M&S contributed 12.3 % to 18.6 % to surface water. The sources and proportion of nitrate in groundwater and surface water exhibited obvious difference. Temporal heterogeneity, land use type, population density and vegetation cover type had influence on nitrate sources. UI results showed that there was uncertainty in nitrate sources tracing process, with SN (mean 0.78), CF (mean 0.64), M&S (mean 0.35) and AD (mean 0.09), respectively. These results will provide vital references for understanding nitrate sources variation, controlling and removing nitrate surplus in groundwater-surface water system in the similar large fresh water lake areas.
追踪硝酸盐来源是解决氮污染问题的关键途径。然而，大型淡水湖区域地下水和地表水硝酸盐来源的季节差异及其动态演变过程和机制仍不明确。本研究于2022年至2023年在中国最大的淡水湖（鄱阳湖）区域采集了126份地下水和地表水水样。采用贝叶斯稳定同位素混合模型、绝对主成分得分-多元线性回归、离子比系数和不确定性指数（UI）来研究鄱阳湖地区地下水和地表水硝酸盐来源的变化及其不确定性。结果表明，人为影响对硝酸盐来源有显著影响，主要受化肥（CF）、土壤氮（SN）以及粪便和污水输入（M&S）的影响。具体而言，2022年至2023年，CF对地下水的贡献率为16.6%至32.4%，SN为26.0%至38.1%，M&S为26.5%至48.2%。CF对地表水的贡献率为38.8%至43.9%，SN为37.6%至40.6%，M&S为12.3%至18.6%。地下水和地表水硝酸盐的来源及比例存在明显差异。时间异质性、土地利用类型、人口密度和植被覆盖类型对硝酸盐来源有影响。UI结果表明，硝酸盐来源追踪过程存在不确定性，SN（均值0.78）、CF（均值0.64）、M&S（均值0.35）和AD（均值0.09）的不确定性分别如此。这些结果将为理解类似大型淡水湖区域地下水-地表水系统中硝酸盐来源变化、控制和去除硝酸盐过剩提供重要参考。
