Biochemical Assessment of Heavy-Metal Contamination of the Soil and Vegetation Cover of Kanonersky Island

The authors have assessed heavy-metal pollution (Cd, Cu, Ni, Pb, and Zn) in the soil and vegetation cover of Kanonersky Island, St. Petersburg. The reconnaissance identified the Western High-Speed Diameter (WHSD) as a significant source of pollution and the territory of the island was divided into four zones due to their functional purpose and wind regime: recreational, transitional, windward, and leeward relative to the WHSD. Pb and Zn were established to be the primary contaminants with concentrations varying within 5–376 and 16–1131 mg/kg for mobile forms and 46–1179 and 64–2903 mg/kg for gross content, respectively. The highest MAC exceedance factor is observed for mobile forms of metals, that is, for Pb (63 in the transition zone) and Zn (50 on the windward side of the WHSD). The total soil-contamination index with heavy metals ranged from 2 to 104 for mobile forms and from 5 to 55 for gross content. Maximum values were recorded in transition and windward zones, due to which soils of these territories fall under the category of moderately polluted. The highest mobility among the considered heavy metals on the island belongs to Pb (with a 29% average share of its mobile forms), while the lowest belongs to Ni (4%). At the same time, their accumulation by plants increases in the series Pb < Cd < Ni < Cu < Zn. The highest values were recorded for Zn and Cu in the leaves of woody plants on the leeward side of the WHSD. The general assessment of the condition of the soil and vegetation cover of Kanonersky Island revealed a moderate degree of soil contamination with localization on the windward side of the WHSD and partially in the transition zone.