Identification of nitrate sources and transformations during precipitation processes in Dagang River basin
To explore the sources and transformation of surface water nitrate in Dagang River Basin,we defined eight sampling points from the upstream to downstream along the Dagang River from which samples of surface water and sediment were collected when precipitation occurred in autumn(November 2020)and spring(March 2021).A total of 20 samples of groundwater,sewage,manure and soils were analyzed with hydrogeochemistry,nitrogen and oxygen isotope tracer technology,and Bayesian mixture model.Results show that:(1)the total nitrogen(TN)concentration of surface water was 3.20mg/L in the autumn and 3.23mg/L in the spring(70.9％in the form of NO3-N),which was higher than the environmental quality of surface water V standard;(2)nitrogen cycling process in the Dagang River Basin was dominated by nitrification,while precipitation led to the seasonal changes in nitrate concentration;(3)domestic wastewater and livestock manure were two main sources of nitrate to the watershed waters,collectively contributing(40.8％±32.8％)in the autumn and(55.8％±27.3％)in the spring,followed by groundwater and soils,while the least by precipitation.
rainfallDagang River Basinnitrogen and oxygen isotopessources of nitrateBayesian mixture modelsource identification
万方数据
维普
