Regional geochemical normalization of the content of trace elements in the snowcover in Tobolsk
A.V. Zakharchenko, D.V. Moskovchenko, A.A. Tigeev
Tyumen Research Centre, Siberian branch of the Russian Academy of Sciences, Institute of the problems of Northern development, Tyumen, Russia
Keywords: norm, microelements, solid phase, aerosol, snow cover
Abstract
Snow cover in the temperate and northern latitudes of Eurasia accumulates atmospheric precipitation during winter. The analysis of the trace element composition of snow cover makes it possible to estimate the level of aerosol pollution of the atmosphere. The estimations are usually made relative to the average background concentrations of elements. However, in a poorly studied region, the selection of background points may be incorrect. We suggest using the upper limit of geochemical baseline variation (ULBL) as a norm. It considers the natural and controlled anthropogenic input of an element and is defined as the sum of the 75-quantile of the distribution of element concentration and the difference between the 75- and 25-quantiles multiplied by 1.5. Using the suggested approach we have detected contamination with Ag, Sn, and Hg in places a priori considered background; a zone of heavy metal contamination at a distance of 9-26 km from the industrial zone; and conventionally "clean" points, where the concentrations of trace elements do not exceed the ULBL. The use of ULBL as a norm enables objective estimation of air pollution over a territory from the results of a single snow survey.
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