Tracing bioavailability of ZnO nanoparticles using stable isotope labeling.
Zinc oxide nanoparticles (ZnO NPs) are widely used in commercial products and knowledge of their environmental fate is a priority for ecological protection. Here we synthesized model ZnO NPs that were made from and thus labeled with the stable isotope (68)Zn and this enables highly sensitive and selective detection of labeled components against high natural Zn background levels. We combine high precision stable isotope measurements and novel bioimaging techniques to characterize parallel water-borne exposures of the common mudshrimp Corophium volutator to (68)ZnO NPs, bulk (68)ZnO, and soluble (68)ZnCl(2) in the presence of sediment. C. volutator is an important component of coastal ecosystems where river-borne NPs will accumulate and is used on a routine basis for toxicity assessments. Our results demonstrate that ionic Zn from ZnO NPs is bioavailable to C. volutator and that Zn uptake is active. Bioavailability appears to be governed primarily by the dissolved Zn content of the water, whereby Zn uptake occurs via the aqueous phase and/or the ingestion of sediment particles with adsorbed Zn from dissolution of ZnO particles. The high sorption capacity of sediments for Zn thus enhances the potential for trophic transfer of Zn derived from readily soluble ZnO NPs. The uncertainties of our isotopic data are too large, however, to conclusively rule out any additional direct uptake route of ZnO NPs by C. volutator.
Department of Earth Science & Engineering, Imperial College London, SW7 2AZ, UK. fiona.larner04@imperial.ac.uk
Fiona
F
Larner
Yuktee
Y
Dogra
Agnieszka
A
Dybowska
Julia
J
Fabrega
Björn
B
Stolpe
Luke J
LJ
Bridgestock
Rhys
R
Goodhead
Dominik J
DJ
Weiss
Julian
J
Moger
Jamie R
JR
Lead
Eugenia
E
Valsami-Jones
Charles R
CR
Tyler
Tamara S
TS
Galloway
Mark
M
Rehkämper
D033304:Amphipoda / Q000378:metabolism*; D000818:Animals; D001682:Biological Availability; D002712:Chlorides / Q000378:metabolism*; D007553:Isotope Labeling; D053768:Metal Nanoparticles; D017967:Zinc Compounds / Q000378:metabolism*; D015034:Zinc Oxide / Q000378:metabolism*
D002712:Chlorides; D017967:Zinc Compounds; C016837:zinc chloride; D015034:Zinc Oxide