China University of Geosciences, Beijing, China.
Center for Hydrogeology and Environmental Geology, China Geology Survey, Baoding, China.
Water Environ Res. 2024 Sep;96(9):e11121. doi: 10.1002/wer.11121.
This study investigates the chemical characteristics, formation, and sources of inorganic nitrogen (IN) of shallow groundwater across the Sanjiang Plain, aiming to enhance drinking water safety management and pollution control. A total of 167 groundwater and 27 surface water samples were collected for constituents and isotopes (H and O). The hydrogeochemical characteristics showed that the major type is HCO- Ca·Mg, with low total dissolved solids and a neutral to weak alkaline nature. Rock weathering processes govern the hydrochemical composition of groundwater. Hydrogen and oxygen stable isotopes analyses revealed that precipitation serves as the main water source. In alluvial areas, oxidative conditions lead to the enrichment of NO-N concentrations, with sewage, manure, and fertilizers being the primary IN sources. In lacustrine areas, intensive rice cultivation results in reductive conditions and strong denitrification processes, causing the loss of NO-N and leaving NH-N as the dominant IN form. Organic matter mineralization is likely a more significant contributor to NH-N concentrations than ammonium fertilizers. These findings provide valuable information for further research on natural sources and groundwater pollution in areas with similar hydrogeological conditions. PRACTITIONER POINTS: Rock weathering processes govern the hydrochemical composition of groundwater, and precipitation serves as the main water source. In alluvial areas, oxidative conditions lead to the enrichment of NO-N. In lacustrine areas, intensive rice cultivation results in reductive conditions and strong denitrification processes. Organic matter mineralization is likely a more significant contributor to NH-N concentrations than ammonium fertilizers. These findings provide references for water management and information for further research on natural sources and groundwater pollution in areas with similar hydrogeological conditions.
本研究调查了三江平原浅层地下水无机氮（IN）的化学特征、形成和来源，旨在加强饮用水安全管理和污染控制。共采集了 167 个地下水和 27 个地表水样品，用于分析成分和同位素（H 和 O）。水文地球化学特征表明，主要类型是 HCO3- Ca·Mg，总溶解固体低，呈中性至弱碱性。岩石风化过程控制着地下水的水化学成分。氢和氧稳定同位素分析表明，降水是主要的水源。在冲积地区，氧化条件导致 NO-N 浓度增加，污水、粪便和肥料是 IN 的主要来源。在湖泊地区，集约化水稻种植导致还原条件和强烈的反硝化过程，导致 NO-N 的损失，留下 NH-N 作为主要的 IN 形式。有机物质的矿化可能比铵肥对 NH-N 浓度的贡献更大。这些发现为进一步研究类似水文地质条件地区的天然来源和地下水污染提供了有价值的信息。
