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Title: Bioaccumulation of CeO2 nanoparticles by earthworms in biochar-amended soil: A synchrotron microspectroscopy study

Author
item SERVIN, ALIA - Connecticut Agricultural Experiment Station
item CASTILLO, HIRAM - European Synchrotron Radiation Facility
item HERNANDEZ-VIEZCAS, JOSE - University Of Texas - El Paso
item DE NOLF, WOUT - European Synchrotron Radiation Facility
item DE LA TORRE ROCHE, ROBERTO - Connecticut Agricultural Experiment Station
item PAGANO, LUCA - University Of Massachusetts
item PIGNATELLO, JOSEPH - Connecticut Agricultural Experiment Station
item Uchimiya, Sophie
item JORGE, GARDEA - University Of Texas - El Paso
item WHITE, JASON - Connecticut Agricultural Experiment Station

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2017
Publication Date: 12/28/2017
Citation: Servin, A.D., Castillo-Michel, H., Hernandez-Viezcas, J.A., De Nolf, W., De La Torre-Roche, R., Pagano, L., Pignatello, J., Uchimiya, M., Jorge, G.T., White, J. 2018. Bioaccumulation of CeO2 nanoparticles by earthworms in biochar-amended soil: A synchrotron microspectroscopy study. Journal of Agricultural and Food Chemistry. 66:6609-6618.

Interpretive Summary: Man-made nanomaterials like nano-ceria enter farms as a part of sludge and manure applied to the soil. Influence of such nanomaterials on soil ecosystems, especially on earthworm, is unknown. This study showed that soil organic carbon controlled the motility, water retention, and physiology of earthworm when nano-ceria is present in farm soils. Depending on the type of soil organic carbon, earthworm can ingest nano-ceria attached to the soil. This will result in the accumulation of man-made nanomaterials within the food chain including the edible food crops.

Technical Abstract: The interactions of nanoparticles (NPs) with biochar and soil components may substantially influence NP availability and toxicity to biota. In the present study, earthworms (Eisenia fetida) were exposed for 28 d to a residential or agricultural soil amended with 0-2000 mg CeO2/kg and with biochar (350°C and 600 °C) at various application rates (0-5% [w/w]). After 28 d, earthworms were depurated and analyzed for Ce content, moisture content and lipid peroxidation. Principal component analysis (PCA) was used to analyze variances among treatments. The results showed minimal toxicity to the worms; however, biochar variety (350°C or 600 °C) was the dominant factor, accounting for 94% and 84% of the variance for moisture content and lipid peroxidation, respectively, in the exposed earthworms. For both soils with 1000 mg CeO2/kg, biochar 600 °C significantly decreased the accumulation of Ce in the worm tissues. However, amendment with biochar 350 °C had mixed responses on Ce uptake by the earthworms. Analysis by µ-XRF and µ-XANES was used to evaluate Ce localization, speciation and persistence in CeO2- and biochar (BC)-exposed earthworms after depuration for 12, 48 and 72 hr. Earthworms from the 500 mg CeO2/kg and 0% BC treatments eliminated most Ce after a 48 h depuration period. However, in the same treatment and with 5% BC-600, ingested biochar fragments with Ce adsorbed to the surfaces were retained in the gut after 48 h. Analysis by µ-XANES results showed that within the earthworm tissues, most Ce remained CeO2 NPs. The present findings highlight that soil and biochar properties have a significant influence in the accumulation and internalization of CeO2 NPs in earthworms; such interactions need to be considered when estimating NP fate and effects in the environment.