Biogeochemical assessment of coastal urban soils and ecological safety

Abstract

As a result of field and laboratory studies, ecological diagnostics of coastal soils was carried out in 11 points of the city of Irkutsk along the coastline of the Angara River in the recreation zone for 5 km. Revealed alkaline soil with pH up to 9.0. An increased sulfate content was found in the aqueous extract of soil substrates. This leads to soil toxicity, especially as a result of the subsequent transformations of sulfates into more toxic compounds -hydrogen sulfide, sulfuric acid and insoluble metal sulfates. Indicators of the biological activity of soils revealed a decrease in the activity of soil enzymes. More than 70% of soil samples were found to be toxic. The parameters of the biogeochemical state of soils indicate the inhibition of the enzymatic process. The inverse dependence of the biological activity of the soil on its pH has been established. The distribution of total forms of heavy metals Pb, Cu, Zn, Ni, Cd, Hg and As at observation points is obtained. The excess of the normative contents of elements was revealed. The studies carried out have shown an increased environmental hazard of the recreation area in the city center and the need for environmental protection measures.