On irregular distribution of mercury in the upper soil horizon: A case study of the Altai region

The influence of various factors on mercury distribution in upper soil hori zons is reviewed in this paper on the example of the Altai region. A conclu sion is drawn that the chemical composition of rocks and the soil type are not critical for mercury accumulation in turf and humus-accumulating horizo ns. At the same time, retention of mercury accumulated by soils depends on specific features of the landscape (hydromorphic properties, susceptibility to deflation, etc.). The influence of geochemical features of soil-forming rocks can be revealed generally by the comparison of statistical data on s oils of background areas and natural mercury anomalies. In the background a reas, the irregularity in the mercury distribution over an area and the reg ular decline of its contents down the vertical sections of soils is governe d largely by global (regional) atmospheric precipitations and by variations in organic matter contents. In the areas of natural mercury anomalies, the mercury concentrations and their variations in the soil-forming bedrock pl ay a major role in element distribution. Elevated Hg concentrations in soil s with the vegetation cover supplying large quantities of organic matter in to them can be accompanied by a lower degree of Hg emission into the atmosp here in the local biochemical migration cycles. This phenomenon should be m ost efficient in background areas.