Assessment of In Situ Immobilization of Lead (Pb) and Arsenic (As) in Contaminated Soils with Phosphate and Iron: Solubility and Bioaccessibility

Abstract

The effect of in situ immobilization of lead (Pb) and arsenic (As) in soil with respectively phosphate and iron is well recognized. However, studies on combined Pb and As-contaminated soil are fewer, and assessment of the effectiveness of the immobilization on mobility and bioaccessibility is also necessary. In this study, a Pb and As-contaminated soil was collected from an abandoned lead/zinc mine in Shaoxing, Zhejiang province of China, which has been treated with three phosphates, i.e., calcium magnesium phosphate (CMP), phosphate rock, and single super-phosphate (SSP) for 6 months in a field study. The ferrous sulfate (FeSO 4 ) at 20 g kg −1 was then amended to the soil samples and incubated for 8 weeks in a greenhouse. The solubility and bioaccessibility tests were used to assess the effectiveness of the in situ immobilization. The result showed that phosphates addition decreased the concentrations of CaCl 2 -extractable Pb; however, the concentrations of water-soluble As increased upon CMP and SSP addition. With the iron addition, the water-soluble As concentrations decreased significantly, but CaCl 2 -extractable Pb concentrations increased. The bioaccessibility of As and Pb measured in artificial gastric and small intestinal solutions decreased with phosphate and iron application except for the bioaccessibility of As in the gastric phase with SSP addition. Combined application of phosphates and iron can be an effective approach to lower bioaccessibility of As and Pb, but has opposing effects on mobility of As and Pb in contaminated soils.

Combined Effect of Ferrous Ion and Biochar on Cadmium and Arsenic Accumulation in Rice

“…The pH value was significantly decreased in 1BC-1Fe(II) treatment owing that Fe(II) accounted for a significant portion of amendment. A similar result was reported by Cui [43], who found that addition of Fe(II) could obviously decrease the soil pH value. It is well known that the Fe-hydroxides may result in a lower pH.…”

Experimental investigation of influence of acid rain on leaching and hydraulic characteristics of cement-based solidified/stabilized lead contaminated clay

“…In this study, lead (Pb) was chosen as the target heavy metal contaminant because it is one of the most toxic elements to human health, and a growing number of sites have been contaminated by Pb in China [9]. Within contaminated soils in the field, Pb speciation is controlled by: (1) specific adsorption or ion exchange adsorption to soil mineral matrix; (2) precipitation of sparingly soluble compounds; (3) formation of complexes with organic matter [10].…”

Sorption of selenate on soils and pure phases: kinetic parameters and stabilisation

“…Numerous studies have been carried out on the behaviour of selenite in soils and pure phases (e.g. Chabroullet, 2007;Coppin et al, 2006;Darcheville et al, 2008;Dynes and Huang, 1997;Haudin et al, 2007;Øgaard et al, 2006;Sposito et al, 1988). However, only a few studies have been conducted on selenate, even though it is potentially the most mobile form (Séby et al, 1998), probably because it is not the major form of Se for in situ measurements (Wang and Gao, 2001).…”

“…This information could be of primary importance in chosing which mineral phases should be used to immobilise Se pollution in a contaminated area, as has already been done for other pollutants (e.g. Cui et al, 2010).…”