YONG Liang1,2, FENG Minquan1,2, FAN Ruiqian3

（1. State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an 710048;
2. Department of municipal and environmental engineering, Xi'an University of Technology, Xi'an 710048;
3. Shanxi Fenhe River Basin Management Co., Ltd, Taiyuan 030002）

Abstract： In this study, by identifying the distribution characteristics of dissolved inorganic nitrogen (DIN) in surface water and shallow groundwater in the study area during the dry season, the dual isotope technique was combined with hydrochemical methods, and the Bayesian stable isotope mixing model (SIAR) was used. Quantitative analysis of the sources of nitrate pollution in the Changhe River Basin provides theoretical support for the restoration and management of the Changhe River Basin's water ecological environment. The results showed that the dissolved inorganic nitrogen (DIN) in the water body in the dry season in the study area was dominated by NO3--N, and the average proportion of NO3--N was 91.56%; The biogeochemical process of the water body was dominated by nitrification; the nitrate mainly comes from feces and sewage; The calculation results of SIAR model show that the contribution ratios of manure and sewage, soil nitrogen, fertilizer and atmospheric deposition to the surface water nitrate in the study area are 40.65%, 30.96%, 25.40% and 2.99%, respectively; The contribution ratios of groundwater nitrate are 41.58%, 30.46%, 25.25% and 2.71%, respectively. Studies have shown that human activities have a strong impact on the water bodies in the study area.Strengthening the infrastructure.

Key words：Dissolved inorganic nitrogen; isotope; SIAR; Changhe River Basin

EARTH AND ENVIRONMENT Vol.51, No.3, Tot No.353, 2023, Page 274