Nitrate is the main contaminant of excessive nitrogen in surface water.Accurate identification and analysis of different source's contribution rates is the key to source control of nitrate pollution.Based on the stable isotopes of nitrogen and oxygen in nitrate and Bayesian mixing model,nitrate transformation processes,proportions of source contributions and the corresponding uncertainty are studied in waters of Xiannyu Lake,Xinyu City.The results show that NO3--N was the primary form of nitrogen in waters of the lake,with its proportion exceeding 60％.Assimilation of phytoplankton existed in the surface waters while nitrification dominated the nitrogen cycling.The main nitrate source was manure/sewage,the proportional contribution of which is 59.4％,and then followed by nitrogen fertilizer(20.7％),soil organic nitrogen(17.3％)and atmospheric deposition(2.6％).The proportional contributions of soil organic nitrogen and fertilizer sources showed the highest uncertainty,and the uncertainty would increase significantly when ignoring the fractionation effect of nitrification.
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万方数据