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Atmospheric and catchment mercury concentrations and fluxes in Fennoscandia

image of Atmospheric and catchment mercury concentrations and fluxes in Fennoscandia

Measurements in Southern Fennoscandia show a weak declining trend in mercury deposition which can be attributed to reduction controls in EU countries. Deposition of mercury in Arctic areas is likely to be governed by the amount of mercury in background air and therefore largely dependent on mercury emissions from mercury sources in the entire northern hemisphere. Hence, further reduction in anthropogenic emissions of mercury will require control measures in the entire northern hemisphere. The so called atmospheric mercury depletion events (AMDEs) are occurring during polar spring. How much of the deposited mercury that remains contra is re-emitted to the atmosphere is, however, crucial for assessing the importance of AMDE in the Arctic environment. Forest soils are an important sink for mercury deposited from the atmosphere. However, this sink can be affected by perturbations in conjunction to common forestry practices and lead to mobilization of the stored mercury and enhanced methyl mercury formation. Similar effects can be expected in areas where climate change results in large increases in precipitation amounts. The processes governing these changes in mercury mobilization are to some extent unknown and general predictions of the magnitude of the changes are thus associated with a large degree of uncertainty

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Air mercury measurements and measurement sites

Sites at which airborne mercury is measured are shown in Figure 1. At most of the sites mercury is measured on a permanent basis within the EMEP and AMAP monitoring network. Whereas at Andøya, Kise and Amderma mercury data from measurement campaigns of 1 to 3 years duration are available, see Table 1. TGM is measured using an automatic method (Tekran 2 537 instruments) with high time resolution at most of the sites except at in Sweden sites, where a manual method is used. Earlier this also was the case in Pallas but since end of 2007, both the manual method and a Tekran instrument is used.

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