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Insights into the fate of antimony (Sb) in contaminated soils: Ageing influence on Sb mobility, bioavailability, bioaccessibility and speciation
Citation:
Diquattro, S., P. Castaldi, S. Ritch, A. Juhasz, G. Brunetti, Kirk G. Scheckel, G. Garau, AND E. Lombi. Insights into the fate of antimony (Sb) in contaminated soils: Ageing influence on Sb mobility, bioavailability, bioaccessibility and speciation. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 770:145354, (2021). https://doi.org/10.1016/j.scitotenv.2021.145354
Impact/Purpose:
Antimony (Sb) is a potentially toxic element (PTE), considered as a priority pollutant by the United States Environmental Protection Agency and the European Union. Antimony concentration in the environment is related to both natural phenomena such as weathering, biological activity, or volcanic activity and anthropogenic inputs. Given that the stability of interactions between Sb and soil colloids, and therefore contaminant mobility, bioavailability and bioaccessibility, can change over time, this should be considered in order to gain a greater understanding of ecotoxicological effects of antimony in soil systems and (more in general) in the environment. In this study we therefore sought to clarify the influence of ageing on the fate and behaviour of Sb in soil by using a combination of well-established and innovative approaches. More specifically, the objective of this work was to investigate the effect of ageing (from 1 day up to 700 days) on the mobility, potential bioavailability, bioaccessibility and speciation of Sb added [as Sb(V)] at two different concentrations (100 and 1000 mg·kg-1) on two distinct soils. In particular, the fate of Sb in soil was studied by sequential extraction to identify labile and relatively immobile Sb pools. Antimony potential bioavailability was addressed with diffusive gradients in thin-films (DGT) probes, while Sb bioaccessibility was studied by using simulated gastric and intestinal solutions in in-vitro tests. Finally, synchrotron based X-ray absorption near-edge structure (XANES) spectroscopy was used to define Sb speciation in soil and its interactions with soil components. The experimental design and the combined use of the above-mentioned techniques were expected to provide a deeper understanding of environmental risk posed by Sb and of possible attenuation mechanisms governed by time.
Description:
The effect of long-term ageing (up to 700 days) on the mobility, potential bioavailability and bioaccessibility of antimony (Sb) was investigated in two soils (S1: pH 8.2; S2: pH 4.9) spiked with two Sb concentrations (100 and 1000 mg·kg−1). The Sb mobility decreased with ageing as highlighted by sequential extraction, while its residual fraction significantly increased. The concentration of Sb (CDGT), as determined by diffusive gradients in thin films (DGT), showed a reduction in potential contaminant bioavailability during ageing. The DGT analysis also showed that Sb-CDGT after 700 days ageing was significantly higher in S1–1000 compared to S2–1000, suggesting soil pH plays a key role in Sb potential bioavailability. In-vitro tests also revealed that Sb bioaccessibility (and Hazard Quotient) decreased over time. Linear combination fitting of Sb K-edge XANES derivative spectra showed, as a general trend, an increase in Sb(V) sorption to inorganic oxides with ageing as well as Sb(V) bound to organic matter (e.g. up to 27 and 37% respectively for S2–100). The results indicated that ageing can alleviate Sb ecotoxicity in soil and that the effectiveness of such processes can be increased at acidic pH. However, substantial risks due to Sb mobility, potential bioavailability and bioaccessibility remained in contaminated soils even after 700 days ageing.
URLs/Downloads:
DOI: Insights into the fate of antimony (Sb) in contaminated soils: Ageing influence on Sb mobility, bioavailability, bioaccessibility and speciation
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