FATE OF MERCURY IN THE ARCTIC Michael Evan ... - COGCI

Fate of Mercury in the Arctic 81
approximately 80 cm. This then would be an indication of an upper limit for natural flux values.
Since this is a minerogenic peat, with geogenic input, this rate is expected to be higher than
deposition due to atmospheric supply alone.
From Figure 18a. page 84, it is seen that the accumulation rate in south Greenland reached its
maximum in 1953 at 164 µg m -2 yr -1 , where it thereafter falls and begins to rise again in the 70’s
with a fall in the late 80’s.
The value in 1995: 14.1 µg m -2 yr -1 is in excellent agreement with the deposition predicted by
the Danish Eulerian Hemispheric Model, DEHM: 12.0 µg m -2 yr -1 for South Greenland (Christensen
et al., 2002, Skov et al., 2003 submitted).
Present day values appear to be declining and are presently an order of magnitude higher than
pre industrial values at the conservative limit, and a factor 3 to 4 at the positive limit.
Atmospheric Hg accumulation rates in southern Denmark
By using dates determined by the high resolution dating method (Goodsite et al., 2002,
Appendix C) an average peat accumulation rate from AD 1950 to AD 1980 was 0.47 cm/y, and
since AD 1980 was 0.21 cm/yr (Shotyk et al., 2003, accepted, Appendix C).
Using these peat accumulation rates, the net atmospheric Hg accumulation rate was calculated
in the same way as for south Greenland, by multiplying the volumetric concentration by the peat
accumulation.
In Figure 18b. page 84, it is seen that in Denmark the maximum Hg accumulation rate was also
found in 1953, at 184 µg m -2 yr -1 . The overall trend in Denmark is the same as that seen in
Greenland. For 1994 the deposition of 14 µg m -2 yr -1 is very comparable to the Danish Eulerian
Hemisphere Model prediction of 18 µg m -2 yr -1 in 1995 (Christensen et al., 2002, Skov et al., 2003
submitted, Appendix C).