Determination of Atmospheric Mercury and its Deposition in Remote Areas of the Northern and Southern Hemisphere

Mercury (Hg) is a pollutant of global concern. Due to its high vapor pressure Hg is a very mobile element and therefore is evident in all environmental compartments and can be both, intra-hemispherically and interhemispherically dispersed.
In order to understand the global mercury cycle and the anthropogenic impact on it, a large number of research activities have been carried out in recent years. On the one hand mercury species in ambient air have been scope of various studies with the objective to characterize the contemporary mercury fate and behavior in the global atmosphere. On the other hand, historical records of mercury in a variety of archives have been used to estimate human impacts on the biogeochemical cycling of mercury.
The first objective of this study was to contribute information on the worldwide distribution and trend of atmospheric mercury. For this the atmospheric species Total Gaseous Mercury (TGM), Reactive Gaseous Mercury (RGM), Total Particulate Mercury (TPM) and mercury in precipitation have been analyzed in remote areas in both, the Northern and the Southern Hemisphere. In order to ensure the determination of reliable data, the establishment of compliant and reliable sampling and analytical set-ups capable for remote sampling areas was the first milestone for this part of the study.
One other intent of the study was to answer the question under which constraints mercury records in peat bogs and lacustrine sediments reflect atmospheric deposition rates and thus can be used to estimate human impacts on the biogeochemical cycling of mercury. With the atmospheric mercury data obtained, contemporary deposition rates were calculated and compared to existing historical mercury records in ombrothrophic peat bogs and lacustrine sediments to test the reliability of these geochemical archives.
The atmospheric data show that there is a significant diurnal and spatial variability of the different species, mainly controlled by meteorological conditions and biogeochemical processes in soils.
The new data contribute to the the existing small data set from remote areas, especially from the Southern Hemisphere, and are a helpful complementary approach to the few stationary sites established for long period observations. Particularly for the region of South America no baseline measurements in remote areas have been performed before. The results provide basic information about the worldwide distribution and trend in atmospheric mercury dynamics.
The calculated mercury wet deposition of 1.3 – 3.5 μg m−2 a−1 found for the different sampling sites in Patagonia show a much better correlation to the Hg accumulation rate found in the lacustrine sediment and evidence that the uncorrected accumulation rates in the upper part of peat bogs and thus the assumed contemporary atmospheric flux might be overestimated.