Increases in Ca/Mg ratios caused the increases in the mobile fractions of Cr and Ni in serpentinite-derived soils in humid Asia

Abstract

Serpentinite-derived soils are characterized by low Ca/Mg ratio and abnormally high Cr and Ni concentrations due to the geogenic sources. The breakdown of parent materials during pedogenesis may lead to the changes in both Ca/Mg ratios and fractions of Cr and Ni. This study hypothesized that total Ca/Mg (Cat/Mgt) and exchangeable Ca/Mg (Cae/Mge) ratios increase with soil development, associated with the increases in potentially mobile fractions (PMFs) of Cr and Ni. Thirty-five soil horizon samples of eight pedons from Japan, Taiwan, Philippines, and Vietnam were collected, and the exchangeable concentrations of Ca and Mg were measured.