Nitrate Source Apportionment and Nitrogen Export Characteristics of Spring Water in a Dolomite Karst World Heritage Site: A Tracing Study Based on Nitrogen and Oxygen Isotopes

Dissolved nitrogen leaching, not just surface processes, significantly drives the evolution of karst rocky desertification in the Shibing Dolomite Karst World Heritage Site. A year-long study using monthly monitoring, hydrochemistry, and nitrate dual isotopes (¹⁵N and ¹⁸O) revealed stark differences between core and buffer zone springs. The buffer zone exhibits high anthropogenic nitrate dominance (>62%) with seasonal peaks, rapid hydrological response, and limited denitrification, while the core area shows stable natural nitrate levels (5–7.4 mg/L) and potential local denitrification. Nitrogen export in the buffer zone surges 4.5 times during the rainy season, primarily as NO₃⁻ (93% of TN), whereas the core area has a higher total nitrogen export flux per unit area (3.34 vs. 0.4 g/m²/a) with a greater proportion of dissolved organic nitrogen (DON). These findings highlight the critical role of dissolved nitrogen in shaping karst landscapes, offering new insights for conservation and management strategies.

Mo, J., Lyu, X., Jiao, S., Zhu, C., & Wang, D. (2026). Nitrate Source Apportionment and Nitrogen Export Characteristics of Spring Water in a Dolomite Karst World Heritage Site: A Tracing Study Based on Nitrogen and Oxygen Isotopes. Sustainability, 18(10), 4939. https://doi.org/10.3390/su18104939