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

Asian Chemistry Letters vol. XX, No 1 (2003) XX-XX
7. Conclusion and future work
The analysis of the concentrations of GEM obtained on the Faroe Islands shows that the average
levels are slightly lower than those observed at Harwell and at Mace Head and the concentrations vary
much more abruptly. In short episodes, high concentrations were observed but neither local sources
nor long range transport can explain the observations. Model calculations based on DEHM gave a
constant level of approximately 1.5 ng/m 3 with slightly lower levels in April and May and could not
support the appearance of high observed levels. Measurement artefacts might again be part of the
explanation.
Furthermore, there is also doubt about the low concentrations. If the low atmospheric concentrations
observed on the Faroe Islands reflect realistic levels, then they indicate that GEM has a shorter
lifetime within the marine boundary layer than is generally believed. This implies that the air sea
exchange of mercury outside the Arctic may be much faster than previously believed, substantially
reducing the estimated lifetime of atmospheric mercury from about 1 year to a much shorter period.
Based on our results, it is strongly recommended that future measurements must be performed by
sampling air through a soda lime trap at all sites. The power supply has to be stable e.g. with use of an
Uninterrupted Power Supply (UPS). From the above discussion it is evident that more atmospheric
studies on the Faroe Islands are needed in order to definitively answer the question of the atmospheric
lifetime of GEM and the connection between atmospheric GEM concentrations and the high Hg levels
measured in peat and in marine mammals on/near the Faroe Islands. Measurements of GEM even
with sophisticated monitors such as a TEKRAN, are not trivial. Each measurement site has
characteristics, which will need to be taken into consideration to ensure a campaign that produces
accurate results and minimise artefacts.
Acknowledgements
We wish to thank Bjarne Jensen and Hanne Langberg, NERI, for technical support, and the National
Historic Museum of the Faroe Islands for lending us their laboratory. Per Løfstrøm is acknowledged
for his advice concerning meteorology and Niels Zeuthen Heidam for administration of the Danish
contribution to the Arctic Monitoring and Assessment programme. The Danish Environmental
Protection Agency financially supported this work with means from the MIKA/DANCEA funds for
Environmental Support to the Arctic Region. The results and conclusions presented are those of the
authors alone and do not necessarily reflect the opinions of our employers or funding agencies.
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