| Summary: | Ritgerðin er skrifuð við Háskóla íslands og Landbúnaðarháskóla Íslands Emissions of particulate matter from the natural sources account for a significant part of the total particulate air pollution. Less industrialized and inhibited regions, such as deserts, can contribute remarkably to air pollution. Iceland is a good example of such areas. The trends in long-term dust activity in Iceland and results from the pioneer field experiments on dust atmospheric and snow measurements are presented in this thesis. Long-term dust frequency in Iceland is based on the meteorological data from 30 weather stations in period 1949-2011. Dust day frequency in Iceland is similar to the major desert areas of the world (Mongolia, Iran, USA, China). Frequent volcanic eruptions with the re-suspension of volcanic materials and dust haze increase the number of dust events fourfold, resulting in 135 dust days annually. The Sea Level Pressure oscillation controlled whether dust events occurred in NE or in southern part of Iceland. The Arctic dust events (NE Iceland) were typically warm and during summer/autumn (May-September) while the Sub-Arctic dust events (S Iceland) were mainly cold and during winter/spring (March-May). A total of 32 severe dust storms (visibility < 500 m) was observed. Dust deposition of 31 – 40 million tons influences areas of > 500,000 km2, while some dust plumes are spanning > 1000 km at times. These results confirm that Icelandic dust sources are the most active in the Arctic/sub-Arctic region. Dust is also distributed over glaciers (about 4.5 million t annually) and oceans (6 – 14 million t annually). Our measurements show that Icelandic dust deposited on snow lowers the snow albedo and reduces the snow density as much as Black Carbon, the most powerful absorbing aerosol. The dust has a marked influence on Icelandic ecosystems. The oceanic deposition of the iron-rich dust can potentially affect the primary productivity in oceans around Iceland, especially in spring and late summer. The ...
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