Field Observed Relationship between Soil Metal Speciation and Precipitation Events: What It Implies?

摘要

@@ INTRODUCTION Metals in soil, especially the heavy metals in arable land, has raised wide concerns about its spatial translocation and entrance to crops. Either of the two aspects is intimately connected to the metals' lability, the nature to migrate, which is determined in large part by the chemical status of the metals. Specifically, one metal in soil can have 4 species with residual component disregarded, the exchangeable component, the carbonates bound component, the Fe-Mn oxides bound component, and the organic bound component. From the perspective of lability, the exchangeable species is the most migratory, followed by the carbonates bound species, which is readily transformed to the exchangeable under a weakly acidic environment; in contrast, the Fe-Mn oxides bound component and the organic bound component are generally more reluctant to migrate. Hence, it is critical to discover the law underlying the variation among the metal species in actual cropland soil.