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Title: Limited transport of functionalized multi-walled carbon nanotubes in two natural soils

Author
item KASEL, DANIELA - Agrosphere Institute
item Bradford, Scott
item SIMUNEK, JIRI - University Of California
item PUTZ, THOMAS - Agrosphere Institute
item VEREECKEN, HARRY - Agrosphere Institute
item KLUMPP, ERWIN - Agrosphere Institute

Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2013
Publication Date: 6/12/2013
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2426.pdf
Citation: Kasel, D., Bradford, S.A., Simunek, J., Putz, T., Vereecken, H., Klumpp, E. 2013. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils. Environmental Pollution. 180:152-158.

Interpretive Summary: Multi-walled carbon nanotubes (MWCNT) are currently used in many industrial applications, but little is known about the fate of MWCNT in the environment. The objective of this study was to investigate the influence of soil structure and water content on the transport and retention of MWCNT in two natural soils. Findings from this study indicated that both soils strongly retained the MWCNT, and that there exists little risk of MWCNT transport through the root zone toward groundwater. This information will be of interest to scientists and engineers concerned with the health risks of MWCNTs to humans and ecosystems.

Technical Abstract: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils.