Variations of mercury in soils in the northern segment of Zemuhe fault zone, southwestern China

The characteristics of mercury (Hg) emissions from the fault zone can be used to understand the fault activity and evaluate the impact of emissions on the environment. Here, the distribution of soil Hg was investigated at the Daqingliangzi (DQL) site within the active Zemuhe fault zone in Sichuan, China. Total mercury in soil (THg) and total organic carbon (TOC) concentrations were analyzed at depths of 0–80 cm at 11 sampling sites. The THg concentrations showed large variations, ranging from 18 to 123 ng/g, with the higher values (94–113 ng/g) occurring within the fault plane profile. A positive correlation was observed between the THg and TOC concentrations. These correlations indicated that the enrichment of Hg most likely resulted from adsorption onto organic matter. The Hg migration and accumulation in the fault zone was related to the fault structure, and the Hg enrichment was mainly driven by natural emissions from the fault. This result could be useful in future studies of fault emission processes at the Earth’s surface.