Multidimensional Drivers of Mercury Distribution in Global Surface Soils: Insights from a Global Standardized Field Survey

This studyprovides new insights into environmental driversand spatial patterns of Hg distribution in global surface soils througha global standardized field survey and machine learning approach. Soil stores a large amount of mercury (Hg) that has adverseeffectson human health and ecosystem safety. Significant uncertainties stillexist in revealing environmental drivers of soil Hg accumulation andpredicting global Hg distribution owing to the lack of field datafrom global standardized analyses. Here, we conducted a global standardizedfield survey and explored a holistic understanding of the multidimensionalenvironmental drivers of Hg accumulation in global surface soils.Hg content in surface soils from our survey ranges from 3.8 to 618.2 & mu;g kg(-1) with an average of 74.0 & mu;g kg(-1) across the globe. Atmospheric Hg deposition, particularlyvegetation-induced elemental Hg-0 deposition, is the majorsource of surface soil Hg. Soil organic carbon serves as the majorsubstrate for sequestering Hg in surface soils and is significantlyinfluenced by agricultural management, litterfall, and elevation.For human activities, changing land-use could be a more importantcontributor than direct anthropogenic emissions. Our prediction ofa new global Hg distribution highlights the hot spots (high Hg content)in East Asia, the Northern Hemispheric temperate/boreal regions, andtropical areas, while the cold spots (low Hg content) are in aridregions. The holistic understanding of multidimensional environmentaldrivers helps to predict the Hg distribution in global surface soilsunder a changing global environment.