基于δ15N、 δ18O及质量平衡混合模型对浑河沈抚段氮素溯源研究

摘要

This paper studies the current situation of nitrogen pollution in Shenfu section of Hunhe River basin,analyzes the source of nitrogen pollution in the area and estimates its contribution rate,and realizes the purpose of tracking and quantifying the external nitrogen accurately,so as to better control the nitrogen load into the Hunhe River basin.The method uses nitrogen and oxygen isotope techniques combined with the mass balance model,the surface water of Shenfu section in Hunhe River Basin was used as the object of study.The water samples and the main pollution sources samples in the study area were collected and tested in three water periods.And the contribution rate of several important end elements in the region was quantitatively estimated by the mass balance hybrid model.The distribution range of δ15N in the water samples was 0.231％ ～ 1.511％,0.102％ ～ 1.364％,0.309％ ～ 1.788％,and the distributions of δ18 O were-0.343％ ～ 0.766％,-0.526％ ～ 0.404％、-0.461％ ～ 0.838％,respectively,in the dry season,normal season,and wet season.The distribution rate of integrated wastewater,agricultural fertilizers and atmospheric precipitation to nitrogen pollution is 12％ ～ 83％,4％ ～ 76％ and 2％ ～ 22％ respectively,and the distribution rate of nitrogen pollution is about12％ ～83％ 、4％ ～ 76％ 和 2％ ～22％.The ammonia-nitrogen and total-nitrogen pollution in the water of the Shenfu section of the Hunhe River basin are much higher than that of the surface water V,and the nitrogen pollution is mainly from the surrounding integrated wastewater discharge,followed by the leaching and precipitation of chemical fertilizers.%目的 研究浑河流域沈抚段氮污染现状,分析区域内氮污染来源,并估算其贡献率,实现准确追踪和定量外来性氮的目的,从而更好控制进入浑河流域的氮负荷.方法 应用氮、氧同位素技术结合质量平衡混合模型,以浑河流域沈抚段地表水作为研究对象,分三个水期对研究区域内的水体样品和周边主要污染源样品进行采集及检测分析,并通过质量平衡混合模型对区域内几个重要端元的贡献率进行定量化估算.结果 在枯水期、平水期、丰水期,水体样品中δ15N值分布范围分别为0.231％～1.511％、0.102％～1.364％、0.309％ ～ 1.788％,δ18 O值分布范围分别为-0.343％～0.766％、-0.526％ ～0.404％、-0.461％ ～0.838％;综合污水、农业化肥和大气降水对氮污染的贡献率分布范围分别为12％ ～ 83％、4％ ～ 76％和2％ ～22％.结论 浑河流域沈抚段大部分水域氨氮和总氮超出地表水Ⅳ类标准的限值,氮污染严重.干流水体氮污染源主要来自周边综合污水的排放,其次来自化学肥料的淋洗和大气降水.