A FIELD INVESTIGATION OF MERCURY IN SOILS ACROSS THE WHITE MOUNTAIN NATIONAL FOREST, NEW HAMPSHIRE: IMPLICATIONS FOR BOREAL FOREST ECOSYSTEMS

Airborne mercury (Hg) deposition across higher altitudes within New England mountain ranges has been linked to increased Hg levels in the blood of the threatened Bicknell Thrush. We hypothesize that mercury in mountain soils will be maximized within the sub-alpine, boreal forests across the White Mountain National Forest. Precipitation totals generally increase with elevation and one might expect the highest levels of Hg to be found in the soils near the highest peaks across the range. However above tree line, the combination of high run-off and the lack thick organic soil development prohibits Hg accumulation. Boreal forests just below local tree-line (4000-4500 ft) are often wet due to frequent cloud cover and provide an organic rich soil that is ideal for Hg sorption. The presence of abundant organic matter in boreal forests also increases the potential for Hg-methylation. We sampled eight vertical profiles across the White Mountain National Forest to investigate the distribution of Hg in mountain soils. We use a Milestone DMA-80 to quantify the total mercury in each sample and the results in general support our hypothesis. Hg concentrations increase as elevation increase and values plateau just below local tree line between 3500-4500 ft.