Distribution and Source of Nitrate in Groundwater in the Hilly-Plain Transition Area of Jianghan Plain Using Dual N and O Isotopes of Nitrate
Kewen Luo , Teng Ma , Shuai Shen
Journal of Earth Science ›› 2026, Vol. 37 ›› Issue (2) : 763 -774.
Nitrogen contamination of groundwater in the Jianghan Plain (JHP) in the middle reaches of the Yangtze River is widespread, but the sources and fate of nitrate (NO3−) in the transitional area between plains and hills are poorly understood. This paper characterized the distribution, sources and transformation processes of NO3− in groundwater in the hilly-plain transition area of JHP through hydrogeochemistry and dual isotopes (δ15N and δ18O-NO3−). The hydrogeochemical results showed that the NO3− in the plain and hilly areas is heterogeneous and controlled by topography. From plain to hilly areas in summer, NO3− in groundwater has a general trend of decreasing with the direction of groundwater flow. The groundwater in the plain area is strongly affected by anthropogenic activities, and the NO3− in the multi-level aquifer gradually decreases with increasing depth. Changes in redox conditions caused by river erosion may be responsible for higher NO3− in groundwater along the eroded banks. The isotopic results showed that NO3− in the hilly area mainly comes from soil organic nitrogen, which is a natural source. While, groundwater NO3− in the plain area is strongly affected by livestock manure and domestic sewage, which may be owing to the high density of residents and the impact of anthropogenic activities.
Jianghan Plain / groundwater / nitrate / isotope / underground water / hydrogeology
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China University of Geosciences (Wuhan) and Springer-Verlag GmbH Germany, Part of Springer Nature
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