IMPACT OF NATURAL FACTORS ON MERCURY IN LAKES OF THE NORTH OF WESTERN SIBERIA

Abstract

The relevance of the study is caused by the fact that mercury is involved in the global planetary biogeochemical cycle and is included in the food chain with the accumulation in organisms of predatory species of animals and in the indigenous population. With respect to Western Siberia, studies are fragmentary, and generalizations are made on small samples, which makes background studies of mercury content in the bottom sediments of lakes relevant in a representative sample. The aim of the study is to analyze and generalize the background space-time observations of the gross mercury content in the bottom sediments, as well as dissolved, depending on natural factors in the middle taiga within the Khanty-Mansiysk Autonomous Okrug. The object of study is the background concentration of dissolved Hg and mercury in the bottom sediments of lakes. 95 lakes, 322 samples of bottom sediments taken at different times were studied. Methods: atomic absorption spectrometry («cold steam» method) determination of mercury in accredited laboratories in accordance with the guidelines. Background environmental monitoring data from 2007 to 2011 were used. Result. The average background concentration of mercury in bottom sediments is 0,046±0,012 mg/kg, dissolved mercury – 0,025±0,014 mg/kg. The highest concentration of Hg was found in the eluvial and transeluvial positions, the lowest – in superaqueous landscapes. The concentration of Hg is maximum in lake-ridge-hollow complex of peat bogs and lowest – in the bottom sediments of lakes in mineral soils. There is a tendency to increase the concentration of mercury in the bottom sediments of lakes from the tundra zone, the Northern taiga to the subzone of the middle taiga. However, bogging increases from south to north, which contributes to increase in mercury content in lake bottom sediments (R=0,4). There is an increase in dissolved mercury in lakes from West to East (longitude) (R=0,6). The assessment of changes in mercury content in bottom sediments suggests that mercury content is higher in winter than in summer. The concentration of dissolved mercury increases from west to east, but mercury from bottom sediments is not consistent with this.

Keywords

• mercury
• sediments
• lakes
• landscape-geographical factors
• dynamics
• subarctic