ANALYSIS OF MERCURY CONCENTRATION IN A NORTHERN MICHIGAN BRYOPHYTE AND EDIBLE SURVEY

Abstract

Mercury (Hg) is a heavy metal and environmental pollutant associated with anthropogenic activity which may cause adverse health effects in top carnivores, including humans (Wolfe et al., 1998). The persistent nature of heavy metal pollutants in ecosystem soils has led researchers to pursue remediation strategies based on the uptake potential of plant and fungi species. Research detailing the efficacy of different plant species as bioremediators is limited, but there is some evidence to suggest that the bryophyte Dicranum scoparium is capable of absorbing and sequestering lead and other heavy metals (Garton & Rausch, 2019; Kondoh et al., 1998). The aim of this survey is to assess the mean Hg concentrations of bryophytes and wild foodstuffs found in dry and dry-mesic northern forests in Northern Michigan. I used linear regression to model the relationship between Hg concentrations in bryophytes and their proximity to anthropogenic activity with the additional context of soil characteristics, such as pH. I found that both soil pH and distance from man-made structures in the A and E Horizons are moderately and negatively correlated. The regression series describing D. scoparium found no strong correlations between Hg concentration and the explanatory variables. Moreover, the regression slopes for Hg concentration and each explanatory variable for G. procumbens and V. angustifolia vary closely around 0, which may be indicative of either no association between variables, or the presence of a constant upper limit of Hg absorption in these speciesAdditionally, ANOVA analysis revealed a statistically significant main effect of species on mean Hg concentration (df=2, 24, F=17.5627, P<0.0001), where D. scoparium had the greatest mean Hg concentration (mean=0.0483, SE=0.0094 μg/kg dry weight) and V. angustifolium had the least (mean=0.0012, SE=0.0004 μg/kg dry weight). These findings affirm that Hg concentrations of Northern Michigan edible foodstuffs G. procumbens and V. angustifolia fall within the safety limit of daily consumption for humans set forth by the EPA, and further support prior claims that D. scoparium is a bioremediator for contaminated soils.