The content and distribution of various forms of carbon in urban soils of southern Russia on the example of Rostov agglomeration

Abstract

The content and distribution of organic and inorganic carbon in soils of Rostov agglomeration were studied. The results obtained by the direct method of combustion catalytic oxidation on a TOC-L CPN Shimadzu carbon analyzer and by the indirect method of wet combustion of organic compounds were compared. The difference in the carbon contents obtained by these methods was the greatest in the root-saturated sod horizons, where it varied from 0.02 to 0.67%; in the humus-accumulative horizons, it did not exceed 0.12%. Generally higher values were obtained by the method of catalytic combustion.In the light-humus A b horizon of the soils buried under the urbic stratum, a statistically reliable decrease in the organic carbon content in comparison with that in the A horizon of the natural surface soils was observed. Middle-profile carbonate-accumulative horizons of the buried and surface soils (B b and B) were characterized by approximately similar contents of both organic and inorganic carbon attesting to the low anthropogenic influence on these horizons. The lower (C) horizons of the buried and surface soils reliably differed in the contents of inorganic carbon, which was higher in the natural surface soils.Data on the diagnostic urbic horizons were conditionally divided into two clusters of sandy and clay horizons. However, this attempt to arrange the results of the organic carbon measurements did not show any definite regularity in the distribution of organic carbon in the urbic horizons because of the high variability of this indicator.