Atmospheric Mercury Accumulation Rates Between 5900 and 800 Calibrated Years BP in the High Arctic of Canada Recorded by Peat Hummocks

Abstract

In this paper, we present the first comprehensive long-term record of preanthropogenic rates of atmospheric mercury accumulation in dated peat deposits for the High Arctic of Canada. Geochemical studies of two peat hummocks from Bathurst Island, Nunavut reveal substantial inputs from soil dust (titanium), marine aerosols (bromine), and mineral-water interactions (uranium). Mercury, however, was supplied to these peat mounds exclusively by atmospheric deposition. Mercury concentration measurements and age dating of the peat profiles indicate rather constant natural "background" mercury flux of ca. 1 microgram per square meter per year from 5900 to 800 calibrated years BP. These values are well within the range of the mercury fluxes reported from other Arctic locations, but also by peat cores from southern Canada that provide a record of atmospheric Hg accumulation extending back 8000 years. Thus, preanthropogenic Hg fluxes in the Arctic were not significantly different from atmospheric Hg fluxes in the temperate zone. In preindustrial times, therefore, the High Arctic was no more important as a sink for global atmospheric mercury than was the temperate zone.

(Pre-) historic changes in natural and anthropogenic heavy metals deposition inferred from two contrasting Swiss Alpine lakes

“…These values are consistent with pre-anthropogenic atmospheric Hg fluxes in the Arctic and temperate zone, which were also 10e20 times lower than recent deposition rates Givelet et al, 2004).…”

Mercury exports from a High-Arctic river basin in Northeast Greenland (74°N) largely controlled by glacial lake outburst floods

“…The 16 toppermafrost samples as well as permafrost cores represent contrasting soil types within the area downstream from the ice-dammed lake where the flooding and the associated erosion is considered most important for sediment transport in the Zackenberg River. Few studies have previously measured Hg concentrations in permafrost (Givelet et al, 2004;Outridge and Sanei, 2010). Those studies reported Hg concentrations in permafrost of peat sites ranging from~0.010 to 0.050 mg kg −1 , which is within the Hg concentration range measured in this study.…”

A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

“…Several historic sediment and peat bog records from remote sites in both the northern and the southern hemispheres indicate a 2-4 fold increase in Hg deposition since pre-industrial times (Engstrom and Swain, 1997;Bindler et al, 2001;Lamborg et al, 2002;Shotyk et al, 2003;Givelet et al, 2004;Fitzgerald et al, 2005;Shotyk et al, 2005). North American and European Hg emissions are decreasing while those in Asia and Africa are increasing but the latter changes are less well documented and thus carry a larger uncertainty (see Table 1).…”