Mercury in the urban area environment in the cryolithozone

Abstract

The geochemical features of mercury migration in the environment of a city located in the permafrost zone are considered. The average Hg content in suspended matter in the surface atmosphere ranges from 0.11–0.22 in winter to 13–14 mg/t in summer. The total annual intake of Hg from explosives from the atmosphere to the surface is estimated at 11 μg/m2/year, 99% of which occurs in the warm season. Analysis of lithochemical surveys in the city showed that the average Hg content in urban soils varies within the range of 6–22 mg/t. The presence of a seasonally thawed layer, frozen and permafrost rocks determines the binary structure of the cultural layer and the contrasting distribution of Hg in soils. It has been established that the abnormal Hg concentrations in the soils of cultural layer are mainly due to the intake of pollutants in the solid and liquid phases and, to a lesser extent, by the intake from the atmosphere and the chemical composition of the alluvial substrate. The occurrence of Hg anomalies in soils of a cultural layer older than 100 years is determined primarily by the biophilic accumulation of Hg in organic objects of vital activity of domestic animals and humans. Maximum Hg contents of up to 2000–5000 mg/t are observed in seasonally thawed soils in the depth range of 1–4 m, with a technogenic impact lasting more than 150 years. In the urban areas with less lasting technogenic impact, Hg is also fixed in seasonally thawed and frozen soils, with an average concentration of 50–120 mg/t, or forms low-contrast anomalies only in the soil-vegetation layer.