Multi-Isotope Tracing Reveals Nitrate and Sulfate Sources and Fate Across Contrasting Activity Zones in a Semi-Arid Basin of Northern China

Authors

• Chang Yue, Inner Mongolia Agricultural University
• Ruizhong Gao, Inner Mongolia Agricultural University
• Limin Duan, Inner Mongolia Agricultural University
• Tianke Su, Inner Mongolia Agricultural University
• Xixi Wang, Old Dominion UniversityFollow
• Tingxi Liu, Inner Mongolia Agricultural University
• Guoqiang Wang, Beijing Normal University

Document Type

Article

Publication Date

2026

DOI

10.1016/j.ejrh.2026.103919

Publication Title

Journal of Hydrology: Regional Studies

Volume

67

Pages

103919 (18 pp.)

Abstract

In semi-arid surface water-groundwater systems, nitrate (NO₃^–) and sulfate (SO₄²^–) are jointly influenced by natural processes and anthropogenic activities, yet how their sources, transformations, and export vary across contrasting activity zones remains insufficiently understood. Integrating hydrochemistry, multiple stable isotopes, a Bayesian isotope mixing model, and representative-section flux analysis, this study investigated the source compositions, transformation processes, and export differences of NO₃^– and SO₄²^– in the Dahei River Basin.   New hydrological insights for the region: Results showed greater SO₄²^– enrichment in high-activity zones, whereas NO₃^– exceedance was more prominent in low-activity zones. In low-activity areas, NO₃^– mainly originated from manure and sewage (35.2%) and soil organic nitrogen (27.7%), whereas high-activity areas showed more mixed NO₃^– sources. For SO₄²^–, sulfide oxidation and manure and sewage were major sources in both zones, contributing 29.8–36.6% and 24.0–24.8%, respectively. Nitrification dominated NO₃^– transformation, whereas SO₄²^– transformation reflected overlapping effects of sulfide oxidation and mineralization, together with contributions from evaporite dissolution. At nested sections in the low and high activity zones, downstream annual cumulative NO₃^– and SO₄²^– fluxes were 3.16 and 8.41 times the upstream values, respectively, reflecting flow accumulation and combined natural and anthropogenic influences. These findings support zone-based source control and tailored water environment management in semi-arid basins.

Rights

© 2026 The Authors.

This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License.

Data Availability

Article states: "Data will be made available on request."

ORCID

0000-0003-3455-3124 (Wang)

Original Publication Citation

Yue, C., Gao, R., Duan, L., Su, T. K., Wang, X., Liu, T., & Wang, G. (2026). Multi-isotope tracing reveals nitrate and sulfate sources and fate across contrasting activity zones in a semi-arid basin of northern China. Journal of Hydrology: Regional Studies, 67, Article 103919. https://doi.org/10.1016/j.ejrh.2026.103919

Repository Citation

Yue, Chang; Gao, Ruizhong; Duan, Limin; Su, Tianke; Wang, Xixi; Liu, Tingxi; and Wang, Guoqiang, "Multi-Isotope Tracing Reveals Nitrate and Sulfate Sources and Fate Across Contrasting Activity Zones in a Semi-Arid Basin of Northern China" (2026). Civil & Environmental Engineering Faculty Publications. 167.
https://digitalcommons.odu.edu/cee_fac_pubs/167