Spatial distribution and sources analysis of nitrate in the Beiluo River Watershed based on nitrogen and oxygen stable isotope
The Beiluo River flows through the ecologically fragile Loess Plateau,as an important source of water for the region.With the rapid development of the economy and the increase of industrial and agricultural activities,the nitrogen pollution has intensified in the Beiluo River,resulting in the deterioration of water quality and not up to the standard.Therefore,water chemistry,nitrogen and oxygen stable isotopic technology,combined with SIAR model,were used to analyze the pollution status,nitrate sources and spatial distribution in the Beiluo River Watershed.The results showed that the overall level of nitrogen pollution in Beiluo River was severe,the total nitrogen(TN)range was 1.70-43.40 mg/L,most of the sampling points exceeded the standard limit(2 mg/L)of Class V water in the"Environmental quality standards for surface water"(GB 3838-2002),and nitrate nitrogen was the main pollutant for inorganic nitrogen.The ammonia volatilization,nitrification and denitrification processes were weak during the migration and transformation of nitrate in water.Thus,the source of nitrate in the Beiluo River mainly came from anthropogenic origins,specifically sewage discharged from human activities and soil erosion.The contribution rate of different nitrate sources was sewage and manure(about 61％)＞fertilizer(about 15％)＞soil organic nitrogen(about 14％)＞atmospheric deposition(about 9％).In the upstream,soil organic nitrogen contributed significantly,while with the increasing urbanization rate and emission of active nitrogen from traffic,atmospheric deposition's contribution increased in the downstream compared to the upstream and midstream.The results provided a scientific basis for the control of nitrogen pollution and water environmental treatment in the Beiluo River.
nitrogen and oxygen isotopenitratethe Beiluo River Watershedsourcesspatial distributionSIAR model
NETL
NSTL
万方数据
维普
