典型干湿交替型湖泊湖水 地下水系统氮素迁移转化影响因素及健康风险

To explore the influencing factors of nitrogen migration and transformation in lake-groundwater system of dry-wet alternating lakes and its potential ecological health risks, taking the Poyang Lake, the largest freshwater lake in China, as the research object, this study collected samples of Poyang Lake water and surrounding groundwater from 2022 to 2023 to explore the influencing degree of environmental factors on nitrogen concentrations and the health risks of three nitrogen species. The research methods employed included Pearson correlation analysis, structural equation modeling (SEM), Monte Carlo random simulation, parameter sensitivity analysis, and isotope tracing method. The results showed that: nitrate nitrogen was the dominant component of the three nitrogen species in both lake water and groundwater in the study area; environmental factors such as pH value, temperature, electrical conductivity (EC), oxidation-reduction potential (ORP), dissolved oxygen (DO), total organic carbon (TOC), and water level difference had significant impacts on the concentrations of the three nitrogen species, with respective impact effects on total nitrogen (TN) of - 0. 28, - 0. 08, 0. 246, 0. 111, 0. 039, -0. 118, and -0. 07; in the lake water-groundwater system of the study area, the proportions of adults and children whose the health risks of the three nitrogen species reached an unaceptable level were 0. 04% ~ 5. 23% and 0. 42% ~ 16. 79%, respectively; the concentrations of the three nitrogen species and exposure frequency exhibited high parameter sensitivity to the results of health risk assessment.