EN
This article focusses on the bio-monitoring of
total Hg (THg), sulfur (TS) and carbon (TC) concentrations
and pool sizes in forest vegetation and soil layers within
the context of a maritime-to-inland transect study in
southwestern New Brunswick. This transect stretches
from the Grand Manan Island in the Bay of Fundy to the
mainland coast (Little Lepreau to New River Beach) and
100 km northward to Fredericton. Along the Bay, frequent
summer fogs are thought to have led to increased THg
concentrations in forest vegetation and soils such that
island THg > coast THg > inland THg concentrations.
Transect sampling was done in two phases: (i) a general
vegetation and soil survey, and (ii) focusing on specific
soil layers (forest floor, top portion of the mineral soils),
and select moss and mushrooms species. By way of
multiple regression, it was found that soil, moss and
mushroom THg and TS were strongly related to one
another, with THg decreasing from the island to the inland
locations. The accumulated Hg pool within the mineral
soil, however, far exceeded (i) the estimated THg pools of
the forest biomass (trees, moss and mushrooms) and the
forest floor, and (ii) the literature-reported and case-study
inferred net input/output rates for annual atmospheric
Hg deposition and sequestration, Hg volatilization,
and Hg leaching. Partitioning the total soil Hg pool into
geogenically and atmospherically derived portions
suggested that mineral soils in temperate to boreal forest
regions have accumulated and retained atmospherically
derived Hg over thousand years and more. These results
are summarized in terms of further guiding forest THg
monitoring and modelling efforts in terms of specific
vegetation and soil sampling targets.