Metal and metalloids speciation, fractionation, bioavailability, and transfer toward plants

Heavy metals and metalloids pollution in in agricultural lands and arable lands has produced widespread environmental problems around the world. HMMs are mobilized in soils, increasing their bioavailability to plants which then enters the food chain. The speciation and bioavailability of HMMs in plants are determined by HMMs species and soil environmental variables. Thus, once HMMs are released into the soil, they contaminate the soil and food crops, posing a health danger to humans. Therefore, HMMs speciation and fractionation mechanisms as well as soil to plant transfer indices must be investigated. The biogeochemistry of HMMs in soils differed depending on the metal and species, as well as whether they were in ionic, neutral, or complex form or occluded in soil solid phase. These forms have determined whether they are available to plants or not. Furthermore, the total amount of HMMs in soil, pH and organic matter, and plant exudation all contribute to their bioavailability or sequestration in soil solids as well inside root cell walls. The bioconcentration factor (BCF), bioaccumulation factor (BAF) and translocation factor (TF), and geo-accumulation factor (Igeo), which represent the amount of HMMs enriched in soil and accumulation in plants are among the soil to plant translocation indexes. Finally, it may be stated that HMMS enter the environment by both natural and rapid anthropogenic sources, necessitating the immediate management of human exposure to these harmful elements. Thus, understanding the fate of HMMs in the environment is required to overcome the problem.