Chemical evaluation methods for the phytoavailability of heavy metals in soils
With the accelerated development of urbanization and industrialization,heavy metal pollution in soils has become an environmental issue of widespread concern,globally.Soil heavy metals could be taken up by plants,posing a serious health risk to humans through food chains.Currently,determining the heavy metal concentrations in soils and assessing the pollution levels are mainly based on the total concentrations of heavy metals in soils.However,the total concentrations can neither reflect the geochemical processes of the heavy metals nor accurately assess the levels of heavy metal pollution in soils,making it difficult to precisely evaluate the threat caused by heavy metals in soils to the biota and environment.By contrast,phytoavailability can be used to characterize the occurrence status and plant absorption process of heavy metals in soils,more accurately evaluating the degree of harm they cause to the biota and environment.Herein,the development process of the concept of bioavailability or phytoavailability was introduced and commonly-used chemical evaluation methods were systematically summarized,including chemical extraction methods(single and sequential extraction methods),free ion activity method,isotope dilution method,and diffusive gradients in thin-films(DGT)technique.Finally,the differences among their theories and applications in phytoavailability determination were also compared.Therefore,this review provides a basis for further research on the phytoavailability of heavy metals in soils,as well as on the prevention and control of heavy metal pollution in soils.
heavy metals in soilsphytoavailabilitychemical evaluation methodchemical extraction methodfree ion activity methodstable isotope dilutiondiffusive gradients in thin-films(DGT)technique
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