Поширення та акумуляція важких металів у ґрунтах призалізничних територій
Spreading and accumulation of heavy metals in soils of railway-side areas

Summary/Abstract: Following the landscape-environmental survey of the lands adjoining the single-track railway No. 193 Chop – Uzhhorod – Sianky –Lviv within Zakarpatska oblast (Transcarpathia), we have identified certain regularities in the spreading, accumulation and dispersion of some heavy metals (Cu, Pb, Zn, Ni) in soils. For the purpose of study, the soils were taken at different distances from the railway (0, 25, 50 and 100 m) within the following key points of the railway under study: Chop, Uzhhorod, Perechyn, Velyky Berezny, and Volosianka. The soil samples taken at the distance of 250 m from the railway were assumed the control group. Mass concentration of acid-soluble forms of heavy metals, considered as the main anthropogenic constituent of heavy metal stock in soils, was determined by means of atomic absorption analysis. Content of heavy metals in soils under study was compared with background data available in scientific literature. The results were evaluated by calculation of concentration factor commonly considered as a reliable and self-descriptive ecological constituent. In general,increased content of heavy metals was shown to be peculiar for soils that directly adjoin the railways (to 25 m); their content in remoter soils decreases considerably. In the control soils (250 m from the railway), the content of heavy metals reportedly significantly decreases as compared with other soils; however partial accumulation of lead, zinc and nickel compounds does take place there too. Dependence between the accumulations of heavy metals and the distance from the railway was described by polynomial equations. Such deviation from the linear distribution can be explained by the height of the railway embankments, absorbing properties of the railway-side plants, migration processes in soils, and direction of prevailing winds. Zinc was established to have the highest value of concentration factor (Кс = 1.04–10.54). Pollutant accumulation was most frequently registered for zinc (76%), nickel (76%) and lead (60%); less frequently for copper (32%). Thus, heavy metals may be ranked by their contents in excess to background values in soils of railway-side areas as follows: Zn = Ni > Pb > Cu. Due to the contents of mobile forms of heavy metals that exceed background values, these metals may be referred to as pollutants. Results obtained for heavy metal distribution in soils of railway-side areas are of importance for the identification of reaction of biotic component of the ecosystems exposed to rail transport, and identification of pollutant-reactive and pollutant-sensitive indicators of the environmental health.

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