临涣矿区地表水中氮的时间变化及同位素组成

Temporal Variation of Nitrogen and Surface Isotope Composition in Surface Water of Linhuan Mining Area

临涣矿区作为我国重要的煤炭基地,长期的煤炭开采及农业生产活动对地表水环境产生严重影响。为探究临涣矿区地表水中氮营养盐的来源及年度变化特征,于不同时间段采集了研究区河水、沉陷积水区样本,测试分析其常规水化学指标、氮营养盐及氮同位素值;运用水化学、同位素及多元统计评价等分析方法探究研究区地表水中氮的时间变化及同位素组成特征。受农业径流和污水的排放及降雨季节变化的影响,2011至2019年间TN和NO 3-N含量均表现出先升高后降低的趋势,而NH 4-N含量变化较小。河水和沉陷区积水δ15 N值范围差异较大,氮来源异同。河水δ15 N值变化范围为0.92%~1.52%,河水中的氮主要来源于粪肥和生活污水。沉陷区积水δ15 N变化范围为-0.2%~0.78%,其来源主要受土壤氮硝化、含氮肥料的径流影响。研究结果为矿区氮污染源判别提供了一种准确的方法,完善了矿区水生生态系统中氮的生物地球化学信息,帮助制定相关措施减少水体氮污染。

As an important coal base in China,Linhuan mining area has long-term coal mining and agricultural production activities that have a serious impact on the surface water environment.In order to explore the source and annual variation characteristics of nitrogen nutrients in the surface water of Linhuan mining area,the conventional water chemical indicators and the values of nitrogen nutrients and isotope were tested and analyzed in the samples of the river and subsidence water in the studied area collected at different time periods,and the temporal changes and isotopic composition characteristics of nitrogen in surface water of the studied area were explored by analytical methods such as water chemistry,isotope and multivariate statistical evaluation.Affected by agricultural runoff,sewage discharges and seasonal changes in rainfall,the TN and NO 3-N contents showed a trend of increasing first and then decreasing from 2011 to 2019,while the NH 4-N contents changed less.The range ofδ15 N value of river water was quite different from that of water in subsidence area,and the sources of nitrogen were similar.Theδ15 N value of river water varied from 0.92%to 1.52%.The nitrogen in river water mainly comes from manure and domestic sewage.The variation range ofδ15 N in subsidence area is-0.2%~0.78%,of which the source was mainly affected by soil nitrogen nitrification and nitrogen-containing fertilizer runoff.The results of this study will provide an accurate method for identifying nitrogen pollution sources in mining areas,improve the biogeochemical information of nitrogen in aquatic ecosystems in mining areas and help formulate relevant measures to reduce nitrogen pollution in water bodies.