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

Asian Chemistry Letters vol. XX, No 1 (2003) XX-XX
Measurements and Modelling of gaseous elemental mercury (GEM) on the
Faroe Islands; a case study of the difficulties of measuring GEM
H.Skov 1,# , M.C.Nielsdóttir 2 , M.E.Goodsite 3 , J.Christensen 1 , C.A.Skjøth 1 , G.Geernaert 4 , O. Hertel 1 ,
J.Olsen 5 .
1 National Environmental Research Institute. Frederiksborgvej 399, DK 4000 Roskilde, Denmark
# Corresponding author, e-mail Address: Henrik.Skov@DMU.DK
2 Present address: University of East Anglia, Norwich England
3 Present address: Department of Chemistry, University of Southern Denmark, Campusvej 55, DK 5230 Odense
M, Denmark
4 Present address: Inst. of Geophysics and Planetary Physics, Los Alamos National Laboratory, MS C-305
Los Alamos, NM 87545, USA
5 Food and Environmental Agency, Faroe Islands
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Gaseous Elemental Mercury (GEM) in the atmosphere was measured on the Faroe Islands from May 2000 to
March 2001. The measured data were analysed together with basic meteorology, trajectories, and modelled GEM
concentrations using the Danish Eulerian Hemispheric Model (DEHM). The measured air concentration time
series shows periods with elevated (>1.5 ng/m 3 of Hg, the generally accepted global background average)
mercury concentrations. We determined that there are two potential natural causes for the higher than expected
levels: local sources and/or long-range transport. After a detailed analysis, it was determined that neither local nor
long range sources were sufficiently responsible for the observed levels and the pattern could not be adequately
reproduced by the DEHM. Measurement artefacts are the most plausible explanation of much of the measurement
pattern. The nature of the artefact is discussed and recommendation for future measurements of GEM is given.
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This paper is dedicated to Professor Thorvald Pedersen who has just retired from his position at the
Institute of Chemistry, University of Copenhagen. Through the years we have benefited from his
genuine interest and knowledge in spectroscopy and atmospheric chemistry.
1.Introduction
Mercury on the Faroe Islands is of both scientific and public concern due to the high concentrations in
e.g. pilot whales and other higher predators of fish, where up to 3 ppm (µg/g) Hg has been measured 1 .
Furthermore, it has been shown that the present levels of mercury in sea animals also have a negative
effect on the health of the local populations, since these animals are an important food supply 2 . High
concentrations of mercury (up to 700 ng/g) have also been observed in peat cores taken on the Faroe
Islands 3 . The profiles suggest that local geological input does not significantly contribute to the
mercury inventory, so the Hg must be primarily supplied by atmospheric deposition, and that the level
of Hg on the Faroe Islands has through time, been higher than levels reported for other European sites.
However the concentrations cannot be directly linked to atmospheric concentrations or deposition, as
the levels are not only a function of deposition, but also bioaccumulation, the runoff area size and the
geochemistry of the profile and it will therefore be important to quantify the rate of atmospheric
accumulation 3 . It has also been discovered that trout from fish farming activities on the Faroe Islands
also contain unacceptably high levels of mercury 4 . In spite of strong indications of high mercury
exposure to marine food chains and the possible high exposure in terrestrial ecosystems (as implied by
the peat core data), there has not been any study reported to date, which explains the sources
responsible for the high mercury levels and/or how to mitigate the problem.
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