ABSTRACT
Selenium (Se) is an essential element for humans and animals. Overall, Se content and Se accumulation with respect to parent rock were higher in wetter and sub-humid sites compared to driest sites. Regarding Se speciation, Se(VI) was found in water and phosphate extracts at the dry sites, which is in agreement with the general predominance of this Se species in oxic soils. The study demonstrated that at large spatial scale, soil Se concentrations were dominated by climate–soil interactions, including pH, clay content, precipitation, aridity and soil organic matter content. Total extracted Se was quantified by ICP-MS/MS, and the Se species were analyzed by high performance liquid chromatography. Regarding Se speciation, Se(VI) was found in water and phosphate extracts at the dry sites, which is in agreement with the general predominance of this Se species in oxic soils. The reasons why aridity, clay content and pH relate to soil Se content and influence its bioavailability for plants are relatively well understood.
