The distribution and elevated solubility of lead, arsenic and cesium in contaminated paddy soil enhanced with the electrokinetic field

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.

Electrokinetic-enhanced phytoremediation of uranium-contaminated soil using sunflower and Indian mustard

“…The lower applied voltages significantly increased U in both shoots and roots compared to no-EKF treatment for both UO 2 and UO 3 treatments (p < 0.05). There were possible mechanisms responsible for electrokinetic enhancement of DU on plant uptake: (1) Acidification in the anode section; (2) potential enhanced mobilization processes from electro migration of uranium ions across the soil profile and electro-osmosis of soil solution/water moving toward the cathode section (Mao et al 2016c).…”

Microbially Induced Carbonate Precipitation Techniques for the Remediation of Heavy Metal and Trace Element–Polluted Soils and Water

“…In recent years, with the rapid development of urbanization and the continuous increase of population, our environment has become polluted and degraded with heavy metals and radionuclides (Han et al, 2002(Han et al, , 2003. A number of techniques for remediation of metal-contaminated sites and waters include soil washing (Mao et al, 2016a), physical separation, stabilization, bioremediation/phytoremediation (Han & Singer, 2007;Han et al, 2004;Su et al, 2005Su et al, , 2007Su et al, , 2008Sridhar et al, 2005Sridhar et al, , 2007Shiyab et al, 2009), electric coupled phytoremediation (Mao et al, 2015(Mao et al, , 2016b(Mao et al, , 2018, etc. Natural materials such as humic substance and new nanomaterials were developed to remove heavy metals and radionuclides from water (Guo et al, 2015(Guo et al, , 2016(Guo et al, , 2018.…”

Pilot-scale electro-kinetic remediation of lead polluted field sediments: model designation, numerical simulation, and feasibility evaluation

“…Many studies proved that the EPI-enhanced EKR (EPI-EKR) is able to deal with a wide range of toxic metals (e.g., Pb, Cd, Cu, Cr, Zn, and Ni) [11][12][13][14][15][16]. However, most of these studies focused on the metal-spiked samples at a laboratory scale, the full-scale remediation of fieldcontaminated sediments was rarely reported.…”