posted on 2021-11-18, 15:04authored bySarah L. Roberts, Jane L. Kirk, Derek C. G. Muir, Johan A. Wiklund, Marlene S. Evans, Amber Gleason, Allison Tam, Paul E. Drevnick, Ashu Dastoor, Andrei Ryjkov, Fan Yang, Xiaowa Wang, Greg Lawson, Martin Pilote, Jonathan Keating, Benjamin D. Barst, Jason M. E. Ahad, Colin A. Cooke
Mercury (Hg) is a pollutant of concern
across Canada and transboundary
anthropogenic Hg sources presently account for over 95% of national
anthropogenic Hg deposition. This study applies novel statistical
analyses of 82 high-resolution dated lake sediment cores collected
from 19 regions across Canada, including nearby point sources and
in remote regions and spanning a full west–east geographical
range of ∼4900 km (south of 60°N and between 132 and 64°W)
to quantify the recent (1990–2018) spatial and temporal trends
in anthropogenic atmospheric Hg deposition. Temporal trend analysis
shows significant synchronous decreasing trends in post-1990 anthropogenic
Hg fluxes in western Canada in contrast to increasing trends in the
east, with spatial patterns largely driven by longitude and proximity
to known point source(s). Recent sediment-derived Hg fluxes agreed
well with the available wet deposition monitoring. Sediment-derived
atmospheric Hg deposition rates also compared well to the modeled
values derived from the Hg model, when lake sites located nearby (<100
km) point sources were omitted due to difficulties in comparison between
the sediment-derived and modeled values at deposition “hot
spots”. This highlights the applicability of multi-core approaches
to quantify spatio-temporal changes in Hg deposition over broad geographic
ranges and assess the effectiveness of regional and global Hg emission
reductions to address global Hg pollution concerns.