title: Soil solution interactions may limit Pb remediation using P amendments in an urban soil.
abstract: Lead (Pb) contaminated soils are a potential exposure hazard to the public. Amending soils with phosphorus (P) may reduce Pb soil hazards. Soil from Cleveland, OH containing 726 ± 14 mg Pb kg-1was amended in a laboratory study with bone meal and triple super phosphate (TSP) at 5:1 P:Pb molar ratios. Soil was acidified, neturalized and re-acidified to encourage Pb phosphate formation. PRSTM-probes were used to evaluate changes in soil solution chemistry. Soil acidification did not decrease in vitro bioaccessible (IVBA) Pb using either a pH 1.5, 0.4 M glycine solution or a pH 2.5 solution with organic acids. PRSTM-probe data found soluble Pb increased 10-fold in acidic conditions compared to circumnetural pH conditions. In acidic conditions (p = 3-4), TSP treated soils increased detected P 10-fold over untreated soils. Bone meal application did not increase PRSTM-probe detected P, indicating there may have been insufficient P to react with Pb. X-ray absorption spectroscopy suggested a 10% increase in pyromorphite formation for the TSP treated soil only. Treatments increased soil electrical conductivity above 16 mS cm-1, potentially causing a new salinity hazard. This study used a novel approach by combining the human ingestion endpoint, PRSTM-probes, and X-ray absorption spectroscopy to evaluate treatment efficacy. PRSTM-probe data indicated potentially excess Ca relative to P across incubation steps that could have competed with Pb for soluble P. More research is needed to characterize soil solutions in Pb contaminated urban soils to identify where P treatments might be effective and when competing cations, such as Ca, Fe, and Zn may limit low rate P applications for treating Pb soils.
authors.affiliation: School of Environment and Natural Resources, 210 Kottman Hall, 2021 Coffey Road, The Ohio State University, Columbus, OH 43210, United States.
authors.forename: John F
authors.initials: JF
authors.lastname: Obrycki
authors.affiliation: U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Cincinnati, OH 45224-1701, United States.
authors.forename: Kirk G
authors.initials: KG
authors.lastname: Scheckel
authors.affiliation: School of Environment and Natural Resources, 210 Kottman Hall, 2021 Coffey Road, The Ohio State University, Columbus, OH 43210, United States. Electronic address: basta.4@osu.edu.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: Basta
mesh_terms: D000143:Acids; D001688:Biological Products / Q000737:chemistry; D002947:Cities; D004787:Environmental Pollution; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis*; D008903:Minerals / Q000737:chemistry*; D009820:Ohio; D009930:Organic Chemicals; D010710:Phosphates / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D012996:Solutions; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000143:Acids; D001688:Biological Products; D008903:Minerals; D009930:Organic Chemicals; D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D012996:Solutions; C471364:pyromorphite; D010758:Phosphorus; D007854:Lead; C027762:bone meal
keywords: Bioaccessibility; In vitro; Lead (Pb); Phosphorus (P); Remediation