Fractionation and mobility of cadmium and zinc in calcareous soils of Fars Province, Iran
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REVIEW PAPER
Fractionation and mobility of cadmium and zinc in calcareous soils of Fars Province, Iran Farzad Rassaei 1
&
Mehran Hoodaji 1 & Seyed Ali Abtahi 2
Received: 23 October 2019 / Accepted: 6 October 2020 # Saudi Society for Geosciences 2020
Abstract This study describes the mobility and chemical fractionation of zinc (Zn) and cadmium (Cd) in eight calcareous soils of Fars province in Iran. A 15 mg kg-1 Zn of zinc sulfate (ZnSO4∙7H2O) and 15 mg∙kg-1 Cd as cadmium sulphate (CdSO4∙8H2O) were added to soils. There were 3 replicate beakers per treatment. After 2 months incubation time, the sequential extraction technique was used to determine the Cd and Zn concentration in Water soluble (Ws), exchangeable (Ex), iron and manganese oxides (FeMnOx), carbonates (Car), organic matter (OM) and residual (Res) forms. The result showed that Cd was mainly extracted in exchangeable fraction (27–32%), while the main portion of Zn was extracted in residual fraction (30–46%). The mean mobility factor (MF) was 58.4 and 22.7% for Cd and Zn, respectively. The higher mobility of Cd in soils indicated that Cd can be easily absorbed by plants and enter to our food chain. Keywords Cadmium . Calcareous soil . Mobility factor . Sequential extraction . Zinc
Introduction Heavy metal pollution risks in soils is a wide environmental problem (Tóth et al. 2016) and raising our concern about food chain safety and human health (Duan et al. 2016; Li et al. 2016; Wu and Sun 2016). Metals can exist in soil solution phase as free metal ions (Mn+), as soluble complexes with inorganic (OH-, CO32-, HCO3 -, SO42-, NO3-, and Cl-) or organic ligands (McLean and Bledsoe 1992). Among the heavy metals, Cadmium (Cd) is considered a more toxic element (Wu et al. 2016). Cd is a non-essential element which can be taken up by plants and enter the human food chain (Adriano 1986). Zn and Cd have comparable physical-chemical properties, and they are maintained in exchangeable soil sites as a divalent ion (Roberts et al. 2003). Zn and Cd dynamic in the soil depend on pH, clay,
Responsible Editor: Amjad Kallel * Farzad Rassaei [email protected] 1
Department of Soil Science, Isfahan (Khorasgan) branch, Islamic Azad University, Isfahan, Iran
2
Department of Soil Science, Shiraz University, Shiraz, Iran
and organic matter. Total content of trace metals does not give useful information about environmentl effect and their movement in contaminated soils (Rassaei et al. 2020a; Jeng and Singh 1993; Kim and McBride 2006). The chemical fractions of heavy metals provide more information about their action in environment and their mobilization-demobilization (Ma and Rao 1997). Sequential extraction is used effectively to determine the chemical forms of heavy metals. By using extractants enhancing from low acidic to high acidic extration solution, we can obtain some data on the bioavailability of metals and their association with soil components (Rassaei et al. 2019a). Metals in the non-residual fractions are assumed to be more available than metals associa
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