Review of nitrogen migration mechanism in Karst water systems of Southern China

Abstract

[Objective] The mechanism of nitrogen transport in karst water system is a critical issue in the study of karst groundwater pollution and plays a key controlling role in the migration process of contaminants within karst watershed. Due to the unique geological structure and hydrological conditions in the karst regions of Southern China, the nitrogen transport process is extremely complex, posing significant challenges in characterizing and simulating its physical processes. [Methods] Relevant domestic and international studies are systematically reviewed. It summarizes and analyzes nitrogen source identification, transformation processes, influencing factors, and simulation approaches. Key gaps and weaknesses in current research are identified. [Results] The primary limitations of current research lie in the predominant focus on the recharge and discharge zones of karst catchments, while studies on the internal processes of underground rivers remain relatively limited. Furthermore, the understanding of chemical processes such as mineralization and dissimilatory reactions and microbial mechanisms driving nitrogen transformation requires further deepening. Additionally, modeling approaches for nitrogen transport and research on emerging contaminants in karst regions are still in their nascent stages. [Conclusion] Future research should commence with enhanced monitoring of karst water system to obtain more comprehensive data for further study; delve into the relationship between microbial and nitrogen transformation to reveal the biogeochemical mechanisms of nitrogen transport in karst water system; develop nitrogen transport models tailored to karst regions to strengthen the study of solute migration mechanisms; and expand the research scope to emerging pollutants such as suspended particulate matter, investigating their impact mechanisms on nitrogen transport.

Keywords

groundwater / karst / underground river / nitrogen / influence factor / migration and transformation / review / biogeochemistry