A Mesocosm Study of Fate and Effects of CuO Nanoparticles on Endobenthic Species (Scrobicularia plana, Hediste diversicolor)

Abstract

The fate and effects of CuO nanoparticles (CuO NPs) were examined in endobenthic species (Scrobicularia plana , Hediste diversicolor), under environmentally realistic conditions in outdoor mesocosms (exposure to Cu at 10 μg L(-1) in particulate (CuO NPs) or soluble salt (CuNO(3)) forms) for 21 days. Labile Cu was determined in water and sediment by using diffusive gradient in thin films. No labile Cu being detected from CuO NPs; the observed effects in invertebrates exposed to CuO NPs were mainly attributed to the toxicity of nanoparticulate rather than dissolved Cu toxicity. Bioaccumulation of CuO NPs was observed in both species. Biomarkers were examined at different levels of biological organization: biochemical markers of defense and damage, biomarkers of genotoxicity (comet assay), and behavioral biomarkers (feeding and burrowing). Behavioral biomarkers, antioxidant defenses (catalase, glutathion S-transferase, metallothionein), and genotoxicity are the most sensitive tools to highlight the effect of soluble or nanoparticulate metal forms. Concerning other biomarkers of defense (superoxide dismutase, lactate dehydrogenase, laccase) and damage (thiobarbituric acid reactive substances, acetylcholinesterase, acid phosphatase), no significant effects were detected. This experiment shows the suitability of mesocosms for studying the environmental effects of nanoparticles.

Comparative environmental fate and toxicity of copper nanomaterials

“…However, stability of nCuO is strongly influenced by salinity and pH (Conway et al, 2015a;Torres-Duarte et al, 2015;Gomes et al, 2011;Buffet et al, 2013). Rapid aggregation and sedimentation of nCuO occurs at high IS (e.g.…”

“…The overall rates of dissolution depend on aggregation, NOM coating, and other ions present Conway et al, 2015a). The dissolution of nCuO is very slow: on the order of weeks in freshwater, and in seawater dissolution is ≤ 1% after months, over a wide range of initial nanoparticle concentrations (10 μg/L-10 mg/L) Conway et al, 2015a;Gomes et al, 2011;Buffet et al, 2013;Buffet et al, 2011;Hanna et al, 2013;Atha et al, 2012). However, these studies were performed under almost saturated conditions, where the maximum solubility of CuO may be reached.…”

Accumulation and toxicity of metal oxide nanoparticles in a soft-sediment estuarine amphipod

“…Estuarine amphipods accumulated Zn and exhibit toxic responses when exposed to ZnO ENPs, although these impacts did not differ from ionic or bulk forms of Zn (Fabrega et al, 2011). Marine worms and clams exposed to CuO ENPs also accumulated Cu and showed toxic effects and these impacts differed only slightly from ionic or bulk forms of Cu (Buffet et al, 2013). However, ZnO ENPs were found to be 17 times more toxic to algae than CuO ENPs (Aruoja et al, 2009).…”

“…Many ENPs and especially metal oxide ENPs aggregate rapidly to the micron scale in seawater and settle from the water column , where they can accumulate in sediments (Buffet et al, 2013). Once in sediments, they may be bound by particulate organic matter (POM), buried, and broken down or transformed by physical and biogenic processes, including bacterial decomposition, bioturbation, or digestion (Farré et al, 2009).…”

“…We also tested the hypothesis that the toxicity of nano-CuO and nano-NiO was due to exposure and possible ingestion of ENPs because the materials dissolve very slowly in aqueous media (Baek and An, 2011;Buffet et al, 2011). Prior work attributed nano-CuO toxicity in a marine polychaete to ingestion of CuO ENPs, not exposure to Cu 2+ (Buffet et al, 2013). Alternatively, biogeochemical conditions in sediments, including oxidizing conditions caused by bioturbation and sulfide concentration, might enhance dissolution, exposing amphipods to elevated metal ions in pore water (Di Toro et al, 1992;Lee et al, 2000).…”