Potential negative consequences of adding phosphorus-based fertilizers to immobilize lead in soil.
A study of the potential negative consequences of adding phosphate (P)-based fertilizers as amendments to immobilize lead (Pb) in contaminated soils was conducted. Lead-contaminated firing range soils also contained elevated concentrations of antimony (Sb), a common Pb hardening agent, and some arsenic (As) of unknown (possibly background) origin. After amending the soils with triple superphosphate, a relatively soluble P source, column leaching experiments revealed elevated concentrations of Sb, As, and Pb in the leachate, reflecting an initial spike in soluble Pb and a particularly dramatic increase in Sb and As mobility. Minimal As, Sb, and Pb leaching was observed during column tests performed on non-amended control soils. In vitro extractions tests were performed to assess changes in Pb, As, and Sb bioaccessibility on P amendment. Lead bioaccessibility was systematically lowered with increasing P dosage, but there was much less of an effect on As and Sb bioaccessibility than on mobility. Our results indicate that although P amendments may aid in lowering the bioaccessibility of soil-bound Pb, it may also produce an initial increase in Pb mobility and a significant release of Sb and As from the soil, dramatically increasing their mobility and to a lesser extent their bioavailability.
Kilgour
Douglas W
DW
Dep. of Civil Engineering, 208 Harbert Engineering Center, Auburn Univ., Auburn, AL 36849, USA.
Moseley
Rebecca B
RB
Barnett
Mark O
MO
Savage
Kaye S
KS
Jardine
Philip M
PM
D000965:Antimony / Q000737:chemistry; D001151:Arsenic / Q000737:chemistry; D005308:Fertilizers / Q000032:analysis*; D007854:Lead / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000737:chemistry*
D005308:Fertilizers; D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus; D007854:Lead; D000965:Antimony; D001151:Arsenic