Relationships Between Physico-Chemical Properties of The Soil and Selenium Speciations From Amik Plain, Turkey

Abstract

The occurrence of selenium (Se) in natural soils is a double-edged sword due to the slight differences between essential, beneficial, and toxic levels of selenium. Therefore, it is crucial to have knowledge about selenium's geochemical speciation. This study was undertaken to determine the relationships between the concentrations of Se species and some key physicochemical characteristics of soils from Amik Plain in Turkey. The species of Se were examined in 179 agricultural surface soil samples by hydride generation atomic absorption spectrometry (HG-AAS) after sequentially extracting different geochemical fractions. The total Se concentration range in the soils was 148.5-3800 mu g kg(-1) and there was a tendency to higher concentrations in the former lake lands and the sand/silt/limestone lithology. The Pearson's correlation and principal component analysis showed that Se concentrations correlated significantly with soil texture, electrical conductivity, clay content, organic matter, ammonium acetate extractable cations, and calcium carbonate equivalent. Keeping in mind that the partition of Se is highly site dependent, the order of average Se fractions were: exchangeable and carbonatebound Se (14.75 3800 mu g kg(-1); 3.65%) < soluble Se (29.503800 mu g kg(-1); 6.67%) < iron /manganese oxide-bound Se (47.89 3800 mu g kg(-1); 9.82%) < residual Se (181.7 3800 mu g kg(-1); 34.23%) < organic matterbound and elemental Se (238.3 3800 mu g kg(-1); 45.64%). The overall data indicated that solute and/or solid transport phenomena were most likely the primary driving mechanism for Se concentrations in soils. This study provides useful data for the distribution of Se and the geochemical distribution of Se species in Amik Plain soils.