Geochemical associations in technogenic soils (technosols) of contrasting hydrological characteristics from the region of Maritsa-Iztok Coal Mine in Bulgaria

Agricultural Academy, “N. Poushkarov” Institute of Soil Science, Agrotechnologies and Plant Protection


Atanassova I., M. Benkova, M. Banov, T. Simeonova, L. Nenova and M. Harizanova, 2018. Geochemical associations in technogenic soils (technosols) of contrasting hydrological characteristics from the region of maritsa-iztok coal mine in Bul­garia, Bulg. J. Agric. Sci.,(Suppl. 2):18-26

Studied were metal associations and contamination status of hydrophilic and hydrophobic technogenic soils from the area of Maritsa-Iztok coal mine region in Bulgaria. Four sites with contrasting hydrologic and acidic properties were chosen for investigation. At two of the sites following humus and non-humus reclamation under grass vegetation, soils were hydrophilic. At the other two sites (non-vegetated and pine-vegetated), soils were severely hydrophobic (water drop penetration time WDPT 10802s - 14440s). The Principle Component (PCA) and cluster analyses performed on the hydrophobic technogenic soils revealed that four principle components were distinguished explaining 80.5% of the total variance of the thirteen variables tested. The first component was loaded by Zn, Co, Ni, Mg and clay content, implying affiliation of the aforementioned metals to overburden clays, the second by WDPT, Cu, Cr, Fe, organic carbon (OC) and cation exchange capacity (CEC) implying affiliation of metals to the organic matrix of the coal and ash, the third, by Mn and Fe, and the fourth by Pb related to other anthropogenic sources. For the hydrophilic Technosols only two principle components were distinguished containing 91% of the total variance of the twelve original variables. Most of the heavy metals and Mg loaded the 1st component as well as the cation exchange capacity (CEC), % clay and OC. Manganese and lead loaded the 2nd component and were not related with rest of the metals, which indicates a different source. In some samples of the hydrophobic Technosols the measured contents of Cu and Pb exceeded the national guidelines for agricultural arable lands. The hydrophobicity of the Technosols seems to be related to the contents of Cu and Cr present in the soil organic matrix.

Keywords: heavy metals, technogenic soil, hydrophobicity, Principal Component Analysis, geochemistry
Abbreviations:WDPT – Water Drop Penetration Time, OC – Organic Carbon, CEC – Cation Exchange Capacity, SOM – Soil Organic Matter, PCA – Principle Component Analysis

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