Abstract
Trace elements mobility in uncontaminated soils even present at typical soil concentrations remains a problem once their availability to plants is assessed. The objective of this study was to develop a relationship between total Cu, Pb and Zn concentrations and their availability to plants. For that purpose, three soil profiles (Entisols, Inceptisols and Alfisols) were selected from model agricultural fields within Peshawar-Pakistan. Soil samples were collected from each horizon of a soil profile and were sequentially extracted for Cu, Pb and Zn into six operationally defined forms: water soluble (F1= deionized water soluble), exchangeable (F2 = MgCl2), carbonate (F3 = Sodium acetate), Fe+Mn oxide (F4= NH2OH), organic (F5 = Ammonium accetate), residual (F6 = HCl/HF/HNO3). The result shows that the total content of Cu, Pb and Zn in Entisols, Inceptisols and Alfisols ranged from 6.33-22.17, 4.20-12.6, 27.51-52.23; 1.65-21.57, 3-13.5, 36.93-54.12 and 11.28-16.59, 3.09-16.8, 52.71- 73.38 mg kg-1 with average value of 11.48, 7.72, 43.2; 14.6, 8.85, 47.5; 13.87, 9.46, 59.65 mg kg-1. Copper, Pb and Zn were found to be at typical soil concentrations. The sequential extraction of Cu, Pb and Zn showed that Cu was strongly associated as carbonate, Pb was as residual and Zn was as oxide fractions. All metals were weakly associated with exchangeable and organic fractions in all soils. Copper was found to be more mobile and available to plants in all soils than Zn and Pb.
S. Siddiqui, R.A. Khattak2. (2010) Trace elements fractionation in calcareous soils of Peshawar-Pakistan , The Journal Soil & Environment , Volume 29, Issue 2.
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