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Evaluation of ecological risk of heavy metals in watershed soils in the Daxia River Basin

Watershed ecological risk is affected by the environment, climate, and human activity. In this study, the Daxia River Basin in northwestern China was regarded as the research area. The remote heavy metal ecological risk assessment model of the basin was constructed using remote sensing data, normalized difference vegetation index (NDVI), and environmental factors. The results show that different areas of the basin have different ecological risk levels depending on the geographical location and the level of human activity. A multivariate linear relationship exists between the NDVI and heavy metal content, precipitation, and temperature, and a correlation coefficient (r) of 0.866 was derived at a significance level of P < 0.01. There was a nonlinear relationship between the average heavy metal content and the Health Risk Index. The model correlation coefficient equals 0.893 at P < 0.01. The results of the study further demonstrate that risk assessment of the basin can be carried out using remote sensing information and environmental meteorological factors. It also reveals that establishing vegetation helps inhibit the migration of heavy metals in the soil.