【摘要】 为探究滇池主要入湖河道的氮素来源及输移特征,研究于雨季对宝象河水系径流氮营养盐进行了系统监测,分析了宝象河径流过程中氮的浓度、赋存形态特征及其变化规律等环境过程,并对不同区位的氮来源进行了示踪.结果表明,干流总氮浓度从上至下呈现增长趋势,河源至中游地区以硝酸盐氮（NO₃^--N）为主,而下游则以氨氮（NH₄⁺-N）为主.流域主要氮源总氮浓度从低到高依次为:雨水、村镇排污口、农田沟渠径流、城市排污口,其中农田沟渠径流以NO₃^--N为主,而其他三类则以NH₄⁺-N为主.雨季宝象河流域各主要氮源的汇入是导致宝象河径流氮浓度及其赋存形态的变化的重要原因,不同氮源的氮赋存形态在一定程度上决定了对应受纳区河道径流氮赋存形态.干流水体δ¹⁵N-NO₃^--N从河源至入湖口呈现先增后减的趋势,其变化范围是6.576‰—9.708‰.流域雨水、农田沟渠径流、村镇排污口和城市排污口等氮源δ¹⁵N-NO₃^--N分别为3.389‰—5.619‰、6.681‰—19.623‰、5.031‰—9.278‰和5.497‰—7.02‰.降雨和土壤径流是河源氮素主要贡献源;农业源和村镇源是上游、中游地区氮素主要贡献源;宝象河下游除了农业源、村镇源外,城市源也是其主要贡献源.研究结果能为滇池流域氮素面源污染精确治理和调控提供依据.更多还原

【Abstract】 To explore the sources and transport characteristics of nitrogen in the main inflow rivers of Dianchi Lake, the concentration of nutritious nitrogen contained in the surface runoff was systematically monitored within the Baoxiang River watershed during the rainy season. The environmental processes, such as nitrogen concentration, occurrence characteristics and associated varying pattern during the runoff flow process were explored. In addition, the nitrogen sources in different reaches were traced as well. The results showed: The total nitrogen（TN） concentration in the main stream of Baoxiang River increased from upstream to downstream. Nitrate nitrogen（NO₃^--N） dominates as the primary occurrence form of nitrogen from the source of river to the middle reaches, while ammonia nitrogen（NH₄⁺-N） is the main form of occurrence from lower reaches to the estuary. TN concentrations from the main nitrogen sources in the basin can be ranked from high to low as: rainwater, rural sewage outlets, farmland ditch runoff, urban sewage outlets, among which, NO₃^--N is the main form of nitrogen in farmland ditch runoff, while the remaining three are dominated by NH₄⁺-N. In the rainy season, the import from the main nitrogen sources within the basin is the leading factor to the variance of nitrogen concentration and its occurrence forms, the forms of nitrogen from different nitrogen sources determines the nitrogen forms within runoff in the receiving areas to a certain extent. In main stream, δ¹⁵N-NO₃^--N content ranges through 6.576‰ to 9.708‰, and it shows a decreasing trend after an increase at first from upstream to downstream. The δ¹⁵N-NO₃^--N concentrations of nitrogen sources, i.e., rainwater, rural sewage outlets, farmland ditch runoff, urban sewage outlets, are 3.389‰—5.619‰, 6.681‰—19.623‰, 5.031‰—9.278‰ and 5.497‰—7.02‰, respectively. Rainfall and soil runoff are the main contributors of nitrogen to the area of the river source, and agricultural sources and village sources are the main contributors of nitrogen in the up and middle reaches. In addition on the sources of agriculture and village, urban source is the main contributor of the downstream as well. In conclusion, the results can be a basis for precise control and regulation of non-point nitrogen source pollution in the Dianchi River Basin.更多还原