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The distribution and elevated solubility of lead, arsenic and cesium in contaminated paddy soil enhanced with the electrokinetic field
Mao, X.; Han, F. X.; Shao, X.; Guo, K.; McComb, J.; Njemanze, S.; Arslan, Z. & Zhang, Z.
Abstract
The objectives of this study were to investigate
fractionation, solubility and potential bioavailability of Pb,
As and Cs in Mississippi River Delta paddy soil under an
electrokinetic field (EKF). Effects of EKF on soil pH
changes and solid-phase distributions of metal(loid)s were
examined. Results showed that fractionation of Pb, As and
Cs was largely determined by the nature of elements,
loading levels and EKF treatment. Native Pb in the soil was
mostly in the amorphous iron oxide, organic matter and
residual fractions, native As in the amorphous iron oxide,
easily reducible oxide and residue fractions while native Cs
in the residue fraction. Added Pb, As and Cs showed distinguished
solid-phase distributions: Pb dominantly in the
organic matter fraction; As in the amorphous iron oxide
fraction, and Cs in the residue with a significant watersoluble
plus exchangeable fraction. EKF treatment is
effective on lowering soil pH to 1.5 near the anode due to
water electrolysis releasing proton which is beneficial for
dissolution of metal(loid)s, increasing their overall solubility.
The acidification in the anode soil efficiently
increased the water-soluble Pb and the exchangeable Cs,
implying enhanced solubility and elevated their overall
potential bioavailability in the anode region while lower
solubility in the cathode area. The building up of watersoluble
As in the anode region may be from electromigration
of As anion from the cathode. This study shows
significant enhancement of redistribution, elevated solubility
and overall bioavailability of Pb, As and Cs in
Mississippi Delta paddy soil under the EKF.
Keywords
Metal(loid); Distribution; Mobility; Bioavailability; Electrokinetic remediation
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