Freshwater Crayfish: A Potential Benthic-Zone Indicator of Nanosilver and Ionic Silver Pollution

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Abstract
Nowadays, silver nanoparticles (AgNPs) are utilized in numerous applications, raising justified concerns about their release into the environment. This study demonstrates the potential to use freshwater crayfish as a benthic-zone indicator of nanosilver and ionic silver pollution. Crayfish were acclimated to 20-L aquaria filled with Hudson River water (HRW) and exposed for 14 days to widely-used Creighton AgNPs and Ag+ at doses of up to 360 µg L-1 to surpass regulated water concentrations. The uptake and distribution of Ag in over 650 exoskeletons, gills, hepatopancreas and muscles samples were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) in conjunction with two complementary U.S. EPA-endorsed methods: the external calibration and the standard additions. Reflecting the environmental plasticity of the two investigated species, Orconectes virilis accumulated in a dose-dependent manner more Ag than Procambarus clarkii (on average 31% more Ag). Both species showed DNA damage and severe histological changes in the presence of Ag. However, Ag+ generally led to higher Ag accumulations (28%) and was more toxic. By the harvest day, about 14 ± 9 % of the 360 µg L-1 of AgNP exposure in the HRW oxidized to Ag+ and may have contributed to the observed toxicities and bioaccumulations. The hepatopancreas (1.5-17.4 µg of Ag g-1 of tissue) was identified as the best tissue-indicator of AgNP pollution while the gills (4.5-22.0 µg g-1) and hepatopancreas (2.5-16.7 µg g-1) complementarily monitored the presence of Ag+.
Funding Information
  • National Science Foundation (14383405)

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