Assessment of the impact of natural processes on the content of heavy metals Lake Onego water

Abstract

The article presents the results of studies conducted in 2014–2015 and 2018 in the water area and shores of Lake Onego, devoted to the study of natural and anthropogenic factors that affect the water quality of different areas of the lake. Among natural factors, river flow provides 50–70 % of chemical substances into the lake. However, in areas of the lake where there are no large tributaries, abrasion or erosion processes on shores play a special role. As a result of work in 2014–2015, morphogenetic classification of shores was done and seven types were highlighted: slightly modified, abrasion, abrasion-accumulative, accumulative, deltaic, lagoon and anthropogenic. The first attempts to carry out a correlation analysis of coastal processes’ impact on water quality of the lake (heavy metals intake) were made. Geoecological research including water (24 samples), bottom (17 samples) and coastal (12 samples) sediments sampling with subsequent determination of Fe, Mn, Al, Zn, Cu, Ni, Cr, Pb, Co and Cd content was conducted in the area of abrasion (Andoma Mountain) and abrasion-accumulative (Pukhta Bay) shores of Lake Onego in October 2018. The dissolved form of metals was determined in water and the mobile form of metals was determined in sediments. Concentrations of metals reflect the chemical composition of lake water in the autumn and exceed maximum permissible concentrations by 10 times for Mn, Fe, Cu, Zn, Pb and Al. According to the results of chemical analysis, correlation analysis was conducted on abrasion and erosion of lake shores and the impact on the quality of Lake Onego coastal waters. There is no influence of bottom sediments in the coastal zone on the content of heavy metals except Al. Statistically significant correlation (correlation coefficient 0.7) has been noted for Al.