Dynamics of Chemical Composition of Valley Soils and Bottom Sediments of the «Vtoraya Rechka» River (Vladivostok City)

Abstract

The purpose of the study is to assess the current ecological state of soils in the valley of the Vtoraya Rechka River and bottom sediments and to identify the features of the seasonal distribution of chemical elements. Materials and methods. The total content of elements in soils and bottom sediments was determined by X-ray fl uorescence analysis on an EDX-800HS spectrometer (Shimadzu). The content of organic matter and acidity - according to standard methods. Result sand discussion. A decrease in acidity (from slightly acidic to alkaline environment) and an increase in phosphorus content (to extremely high levels) in soils and bottom sediments with increasing anthropogenic load were revealed. In the process of urbanisation, Pb, Zn, Mn, Cu, Ni, Cr accumulate to the greatest extent in the upper horizons of soils and Zn, Sr, Cu, Mn, Pb, V in the bottom sediments. An increase in the content of heavy metals in bottom sediments was revealed in autumn period. The values of geoecological indicators PI and NPI of the state of the urban environment indicate the degradation of the surface layer of soils and a strong degree of pollution with heavy metals; pollution of bottom sediments varies from medium to strong. The index of chemical pollution Zc indicates the permissible level of pollution. The potential ecological risk in the study area is insignifi cant, the level of ecological risk for benthic organisms is medium-low. Conclusion. The use of diff erent pollution indicators revealed a mixed picture in assessing the ecological status of soils.