Spatial distribution, influence factors, and ecological health impacts of soil fluorine in the Hulan River Basin, Heilongjiang Province

Objective This study examines the spatial distribution of soil fluorine in the Hulan River Basin, Heilongjiang Province. It analyzes the influential mechanisms of natural and anthropogenic factors on its enrichment and migration and evaluates its associated potential hazards to the regional ecosystem and human health.

Methods This study selects the Hulan River Basin as the research area, utilizing geochemical survey data of land quality at a scale of 1∶250 000 to create geochemical maps of elements and understand the spatial distribution characteristics of fluorine content in surface soil and parent material within the basin. By combining the distribution patterns of fluorine in soil vertical profiles, the study further explores the influencing factors of soil fluorine content.

Results The results indicate that the average fluorine content in the surface soil of the Hulan River Basin is 471.7 mg/kg, slightly higher than the average for the A horizon of Heilongjiang Province, while the average fluorine content in parent material is 529.84 mg/kg, slightly lower than the average for the C horizon of Heilongjiang Province. The spatial distribution of fluorine in the surface soil and parent material of the Hulan River Basin is generally consistent, reflecting a clear inheritance.

Conclusions The fluorine content in the study area is mainly concentrated at the margins, with high−value and excessive areas indicating potential environmental ecological risks, which only account for 9.57% of the study area. High−value areas with fluorine content greater than 700 mg/kg are primarily distributed in Zhaodong City, Qinggang County, and the jurisdiction of Harbin City. The fluorine content in the soil shows a significant positive correlation with TFe₂O₃ and Al₂O₃ and is evidently influenced by pH, lithology, and topography. The results of this study provide fundamental data for the monitoring of soil ecological environment quality and the assessment of ecological health in the Hulan River basin, and they hold significant reference value for regional ecological conservation.