Abstract
Silver nanoparticles (AgNPs) are efficiently converted during the wastewater treatment process into sparingly soluble silver sulfides (Ag2S). In several countries, sewage sludge is used as a fertilizer in agriculture. The bioavailability of sulfidized silver to the terrestrial isopod Porcellio scaber was investigated. Sewage sludge containing transformed AgNP was obtained from a lab-scale sewage treatment plant operated according to guideline OECD 303a. The results of transmission electron microscopy with energy dispersive x-ray of sludge samples suggest that AgNP were completely transformed to Ag2S. Adult isopods were exposed to OECD 207 soil substrate amended with the AgNP spiked sludge for 14 d (uptake phase) followed by an elimination phase in unspiked soil of equal duration. Most of the silver measured in P. scaber at the end of the uptake phase was found in the hindgut (71%) indicating that only a minor part of the estimated silver content was actually assimilated by the isopods with 16.3% and 12.7% found in the carcass and hepatopancreas, respectively. As a result of this, silver content of the animals dropped following transition to unspiked sludge within two days to a third of the previously measured silver concentration and remained stable at this level until the end of the elimination period. This study has shown that Ag2S in sewage sludge is bioavailable to the terrestrial isopod P. scaber. This article is protected by copyright. All rights reserved
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