Pedosphere 22(3): 304--313, 2012
ISSN 1002-0160/CN 32-1315/P
©2012 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effect of wetting-drying cycles on redistribution of lead in some semi-arid zone soils spiked with a lead salt
H. KHODAVERDILOO1,2, M. RAHMANIAN1, S. REZAPOUR1, S. GHORBANI DASHTAKI2, H. HADI3 and F. X. HAN4
1 Department of Soil Science, Urmia University, Urmia 57135-165 (Iran)
2 Department of Soil Science, Shahrekord University, Shahrekord 88186/34141 (Iran)
3 Department of Agronomy and Plant Breeding, Urmia University, Urmia 57135-165 (Iran)
4 Department of Chemistry and Biochemistry, Jackson, State University, Jackson, MS 39217-0510 (USA)
ABSTRACT
      Mobility and bioavailability of lead (Pb) could be affected considerably by soil physicochemical properties;however, less is known about the effect of Pb levels and aging time. This study was conducted to evaluate the effects of Pb levels and wetting-drying (WD) cycles on distribution and bioavailability of Pb in three semi-arid zone soils treated with different levels of Pb (NO3)2. Wetting-drying cycles simulated the actual field irrigation in the semi-arid soils. A soil with a long history of Pb contamination was also taken as a reference soil. The soils were spiked with various levels of Pb and incubated under WD cycles for 160 d. Sequential extractions and batch sorption experiments were performed to assess the fractionation of Pb in the spiked soils. Redistribution index (Uts) and reduced partitioning parameter (IR) were applied to semi-quantify the distribution of Pb in the spiked soils. A small amount of Pb sorbed was desorbed by the soils, indicating a strong and irreversible binding of Pb in the studied soils. Contribution of carbonate-bound (Car) and residual (Res) Pb fractions to the total Pb of the soils was more than 97%. The Car, soluble plus exchangeable (SE), and organic matter-bound (OMB) fractions of Pb were transferred to the Res fraction under the WD cycles. The IR and Uts values were influenced by Pb loading levels and WD;therefore, the Pb lability and/or redistribution pattern could semi-quantitatively be assessed via these parameters. At the end of the experiment, the IR and Uts values for the Pb salt-spiked soils did not show the quasi-equilibrium state. The lability of Pb in the soils decreased with increasing incubation time and showed a strong dependence on Pb levels and soil chemical composition. WD cycles significantly affected the overall lability of Pb in soils through influencing the redistribution of Pb among solid-phase components.
Key Words:  bioavailability, heavy metals, mobility, redistribution index, reduced partitioning parameter
Citation: Khodaverdiloo, H., Rahmanian, M., Rezapour, S., Ghorbani, D., Hadi, H. and Han, F. X. 2012. Effect of wetting-drying cycles on redistribution of lead in some semi-arid zone soils spiked with a lead salt. Pedosphere. 22(3): 304-313.
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