A Hydropedological Perspective of Mercury Distribution in Soils of the Black Moshannon Lake Drainage Basin.

Pennsylvania freshwater resources have varying degrees of  mercury (Hg) contamination from anthropogenic atmospheric deposition and mining.  The transport of terrestrial Hg across the landscape is understood to be enhanced by complexation with soil organic carbon (SOC).  Some freshwater reservoirs located in environments that accumulate Hg and SOC, such as those in forested areas with abundant wetlands and minimally productive surface waters, may be especially prone to substantial Hg accumulation in SOC.  We present results that examine hydropedological controls on Total Hg hillslope transport and accumulation in subaqueous soils (in this case legacy sediments) from Black Moshannon Lake, PA.  Results suggest that Total Hg follows a known, and thus predictable, pathway controlled by the presence of SOC and soil horizon features that drive interflow to subaqueous soils (in our case a fragipan subsoil horizon).  Soil Total Hg is concentrated in redoximoprhic features, which presents a problem for future subaqueous soil Hg accumulation as water tables in the presence of redoximorphic features may periodically release Hg for downslope transport to the subaqueous soil.  Lastly, in comparison to their unflooded upland state, legacy sediments (present subaqueous soils) have accumulated twice as much SOC in under 100 years.