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Factors Affecting the Bioaccessibility of Pb in Soils Amended with Phosphate: A Meta-analysis and Bench-scale Study

Mayer, Manfred M
http://rave.ohiolink.edu/etdc/view?acc_num=osu1650482735516211

Abstract Details

2022, Master of Science, Ohio State University, Environment and Natural Resources.
Measuring the reduction of in vitro bioaccessible (IVBA) Pb from the addition of phosphate amendments has been researched for more than two decades. The mean change in IVBA Pb as a fraction of total Pb (AC) and relative to the IVBA Pb of the control soil (RC) was determined with a random effects meta-analysis. The addition of P to contaminated soils consistently reduced IVBA Pb. The mean AC was approximately -12% and mean RC was approximately -25% based on 76 soils that measured IVBA Pb with a method other than EPA Method 1340. This analysis determined that soluble amendments reduce bioaccessible Pb more than insoluble amendments, phosphoric acid is more effective than other phosphate amendments, and urban Pb contamination, associated with legacy Pb-paint and tetraethyl Pb, showed lower reductions than other Pb sources. Meta-regression identified high IVBA Pb in the control, low incubated soil pH, and high total Pb with the greater reductions in AC and RC. In order to facilitate comparisons across future remediation research, a set of minimum reported data should be included in published studies and researchers should use standardized in vitro bioaccessibility methods developed for P-treated soils. Meta-analysis identified lowered incubated soil pH as correlated with greater reductions in IVBA Pb but previous studies have found purposeful acidification to have no significant effect on IVBA Pb. In this study, three soils (IDs: AG, TH, SA), previously incubated with triple superphosphate, were acidified to pH 3 with 6M trace-metal grade HCl, and subsequently neutralized with 6M NaOH, to determine if acidification of soil influences IVBA Pb in soils amended with phosphate. The acidification of soil took varying amounts of HCl and markedly less 6M NaOH to return soils to initial pH. The treatment effect ratios (TER) for acidification and neutralization varied by soil. No significant differences were observed for any treatment in SA soil. The acidified treatments had significantly lower bioaccessible Pb for the other two soils with a TER of 0.52 for TH soil and 0.70 for AG soil. Only TH soil had a neutralized treatment which was significantly lower than the control (TER of 0.76). Importantly, no increase in bioaccessible Pb was observed in any soil implying no increased risk from soil acidification. Further primary research is needed to determine the relationship between different soil properties and reduction in bioaccessible Pb attributable to the addition of P amendments.
Nicholas Basta (Advisor)
Steven Lower (Committee Member)
M. Scott Demyan (Committee Member)
Environmental Science; Soil Sciences
Lead (Pb); Phosphorus (P); Soil Remediation; Bioaccessibility

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Citations

  • Mayer, M. M. (2022). Factors Affecting the Bioaccessibility of Pb in Soils Amended with Phosphate: A Meta-analysis and Bench-scale Study [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1650482735516211

    APA Style (7th edition)

  • Mayer, Manfred. Factors Affecting the Bioaccessibility of Pb in Soils Amended with Phosphate: A Meta-analysis and Bench-scale Study. 2022. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1650482735516211.

    MLA Style (8th edition)

  • Mayer, Manfred. "Factors Affecting the Bioaccessibility of Pb in Soils Amended with Phosphate: A Meta-analysis and Bench-scale Study." Master's thesis, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1650482735516211

    Chicago Manual of Style (17th edition)

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