Accumulation and migration of heavy metals in soils of the Rostov region, south of Russia

Abstract

Purpose The main aim of the study performed during 6 years was to determine the specific features of heavy metal contamination of soil cover in the city of Rostov-on-Don and its agglomeration. It was supposed to answer the question: Does soil inherit heavy metals mainly from the parent rocks, or they enter the soil mainly as a result of anthropogenes in the city condition. Materials and methods Seventeen soil profiles were established in different parts of the Rostov agglomeration, within the city and in the urbanized agricultural region. The following objects were studied: (1) calcareous ordinary chernozem under steppe vegetation (fallow) and under trees (parks): soils of natural structure insignificantly affected by urbanization processes; (2) urbostratozems: soils of natural structure overlain by loose anthropogenic deposits; (3) screened urbostratozems (or ecranozems): soils of natural structure overlain by asphalt and/or another impermeable surface. The contents of heavy metals were determined by X-ray fluorescence. The degree of soil contamination with heavy metals was assessed by comparing their content with the MPC values (danger coefficient method) or using the total contamination factor Zc. Results and discussion The comparison of chernozems under different plant covers shows that the woody plants capable of retaining moisture in the soil and more deeply wetting the soil layer decrease the accumulation of vanadium, chromium, cobalt, nickel, and copper in the surface layer. The accumulation coefficients of these metals in urbostratozems are still lower for some reason. At the same time, an increase in the accumulation of zinc and lead is observed in the surface layer of soils under the forest canopy, as well as in the urbostratozems. In the Urbostratozems, screened by dense surfaces, a high variation is observed, which is related to the different times of soil sealing with asphalt.Conclusions The results showed that the concentrations of most elements in the parent rock of Rostov-on-Don exceed the background values, and those of some elements exceed the MPC levels. The main source of accumulation of these elements in the soil profile is the parent rock. Additional input from anthropogenic sources is contributed by the accumulation of such elements as chromium, nickel, zinc, and lead.

Influence of the soil sealing on the geoaccumulation index of heavy metals and various pollution factors

“…This could depend mainly on the type of substrate (e.g., debris, garbage, waste) and the origin of the pollutants such as sewage, sludge, and road traffic, which are characteristics for urban soils (Luo et al 2012b ). Similar conclusions were presented by Bezuglova et al ( 2016 ) who studied sealed and non-sealed soil in Rostov-on-Don. Total contamination factor Z c (Revich et al 1985) was used to show that the sealing of urban soils reduces the vertical migration of heavy metals in the soil profile.…”

“…The determination of the level of risk of soil contamination with heavy metals depends on their content in the parent rock and on the technogenic deposition in the surface layers. In soils of Rostov-on-Don developed on loess, the content of heavy metals in parent rock was higher than the geochemical background (Bezuglova et al 2016 ).…”

Effect of Natural and Technogenic Factors on the Mobility and Transformation of Metal Compounds in Soil

“…The HM contents gradually decrease with distance; their contents in remote soils (plots 9, 10) approach the background level (Belousova, 2001;Bezuglova et al, 2016;Minkina et al, 1998;Nikityuk, 1998;.…”

Molecular structure of humus acids in soils

“…The geographic location is affected by the relatively mild dry winters with frequent thaws and moderately hot summers with considerably long no‐frost periods and a high average of positive temperatures (3200–3500°C). Therefore, local soils have certain genetic features and chemical properties that include relatively low humus content ( Bezuglova , ; Bezuglova and Khyrkhyrova , ).…”