The deposition of mercury in throughfall and litterfall in the lake champlain watershed: A short-term study

Abstract

As part of an ongoing study of the atmospheric deposition of Hg in the Lake Champlain watershed, event throughfall, event precipitation, ambient, green foliage, and litterfall samples were collected and analyzed for Hg from a mixed hardwood forest in Underhill Center, VT, for six weeks during the months of August and September 1994. During this time period, the volume-weighted mean Hg concentration in throughfall (12.0 ± 8.5 ng ℓ −1) was higher than in precipitation (6.5 ± 2.8 ng ℓ −1). In August and September 1994, the total deposition of Hg in throughfall was estimated to be 3.1 μgm −2 (1.9 μg m −2 in precipitation) to the deciduous hardwood forests in the Lake Champlain basin. The mean Hg concentration in litterfall (53.2± 11.4 ng g −1) was significantly greater than the mean concentration in green foliage (34.2 +7.2 ng g −1), suggesting uptake of Hg from the atmosphere by foliage. Estimated annual litterfall deposition to the Lake Champlain basin was 13 μg m −2. This study suggests that throughfall and litterfall play a significant role in the cycling and deposition of Hg in the Lake Champlain watershed.