Relative importance of soil properties and heavy metals/metalloids to modulate microbial community and activity at a smelting site

Abstract

Heavy metals/metalloids have adverse effects on soil microorganisms, but the underlying environmental controls remain unclear. This study aims to investigate the influences of multiple heavy metal/metalloid contaminations on soil microbial communities, as well as the effects of soil properties. Soil samples were collected from a typical Pb/Zn smelter in China. Ecological drivers including soil properties and heavy metal/metalloid contents were determined to evaluate their effects on soil microbial biomass, activity, and community. heavy metals/metalloids had adverse effects on soil microorganisms, as reflected by significant decreases of soil microbial biomass, activity, and bacterial α-diversity with increased contamination levels. The Mantel test and variation partition analysis (VPA) revealed that heavy metals/metalloids strongly affected the bacterial community structure, while soil properties contribute mostly to the variation of microbial activity. Additionally, the influences of soil properties (e.g., total nitrogen, available phosphorus, pH) on microbial biomass, activity, and α-diversity were significant, and stronger than the effects of heavy metals/metalloids. Notably, the interactions between heavy metals/metalloids and soil properties were significant and could explain 61.08% and 33.05% variation of the bacterial community structure and microbial activity, respectively. These findings demonstrate that the overall effects across soil properties and heavy metals/metalloids are interactive, suggesting that evaluation of the effects of heavy metals/metalloids should also take into account the soil properties.