Potential Negative Consequences of Adding Phosphorus‐Based Fertilizers to Immobilize Lead in Soil

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Abstract
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.
Funding Information
  • Strategic Environmental Research and Development Program

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