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Fate and lability of silver in soils: Effect of ageing
Citation:
Settimio, L., M. McLaughlin, J. Kirby, K. Langdon, E. Lombi, E. Donner, AND K. Scheckel. Fate and lability of silver in soils: Effect of ageing. W. Manning (ed.), ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 191:151-157, (2014).
Impact/Purpose:
The use of silver (Ag) and silver nanoparticles (AgNPs) in applications such as solar energy, water purification, medicine and nanotechnology is rapidly increasing. Commonly exploited for their antibacterial properties, Ag and increasingly AgNPs are being used in a range of consumer products but this may also lead to environmental risks following their potential release into the environment. There is a lack of understanding regarding the solid phase speciation and lability of Ag and its ageing in natural soils. Therefore the aim of this study was to examine the fate and lability of added soluble Ag over time by measuring labile Ag (E-value) concentrations and the solid-phase speciation of Ag (XANES) in soils. This will provide an insight into the long-term fate of Ag+ ion added to soils and the mechanisms or interactions with soil components that can affect its lability and bioavailability to soil organisms.
Description:
The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectroscopy. After two weeks of ageing the E-values for Ag decreased by 20 – 90% with a further decrease of 10 – 40% after six months. The overall decrease in labile Ag for all soils after the 6 month ageing period was 50 – 100 %. The ageing was more rapid and pronounced in the alkaline soils. XANES results for Ag in soils indicated that for the majority of soils the added Ag+ was reduced to metallic Ag over time, and associations with Fe-oxohydroxides and reduced S groups in organic matter also decreased Ag lability. Strong positive correlations were found between metallic Ag and non-labile Ag and between the organic carbon and Ag bonded with S species.
