2007 Progress Report: Carbon Nanotubes: Environmental Dispersion States, Transport, Fate, and Bioavailability

EPA Grant Number: R833321
Title: Carbon Nanotubes: Environmental Dispersion States, Transport, Fate, and Bioavailability
Investigators: Weber, Walter J. , Huang, Qingguo
Institution: University of Michigan
EPA Project Officer: Hahn, Intaek
Project Period: March 1, 2007 through March 1, 2010
Project Period Covered by this Report: September 1, 2006 through August 31,2007
Project Amount: $371,886
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: a Joint Research Solicitation-EPA, NSF, NIOSH, NIEHS (2006) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Health Effects , Nanotechnology , Health , Safer Chemicals

Objective:

Our overarching goal is to evaluate factors that control the environmental dispersion states, transport, fate, and bioavailability of carbon nanotubes, thereby providing a foundation for human and ecological risk assessment. Specifically, single-walled and multi-walled 14C-labeled carbon nanotubes will be synthesized, purified, and characterized using techniques previously established in our lab. These radio-labeled materials will then be used to systematically investigate i) the dispersion states of these nanomaterials under typical environmental conditions, ii) their transport behaviors within and through a series of different types of soil and sediment media, and iii) their bioavailability to selected critical aquatic and terrestrial food-chain organisms.

Approach:

We have developed and refined a means for producing single-walled and multi-walled 14C-labeled carbon nanotubes by using radioactively labeled methane as a feedstock for the synthesis of carbon nanotubes via chemical vapor deposition methods. Carbon nanotubes will be mixed with natural organic matter and subjected to a wide range of aquatic conditions (i.e., pH, ionic strength, etc.) to elucidate their dispersion state in natural environments. Carbon nanotube transport through a series of soil and sediment sorbent materials having different geochemical properties will be tested in dynamic column studies, and relationships among the breakthrough behaviors and the properties of both the nanotubes and the geosorbent materials will be analyzed. Carbon nanotube bioavailability to a fish, an aquatic worm, and an earthworm will be tested in lab-scale systems to examine the potentials of these nanomaterials to enter food chains in different environments, and factors controlling ecological bioavailability will be determined.

Progress Summary:

We have developed methods to synthesize and purify carbon-14 labeled single- and multi-walled carbon nanotubes and have characterized their properties using a suite of analytical methods. These nanotubes were used to test the mobility of multi-walled carbon nanotubes (MWCNT) in porous media through one dimensional flow-through column experiments under conditions representative of subsurface and drinking water treatment systems. The goal of this work was to determine dominant MWCNT removal mechanisms and factors that control MWCNT transport. Results demonstrate that pore water velocity strongly influenced MWCNT transport, a result that stands in contrast to traditional colloid filtration theory, which suggests a relatively minor effect of flow velocity in comparison to Brownian diffusion. Experiments conducted at different ionic strengths indicate that both particle deposition and straining are important MWCNT removal mechanisms from the aqueous phase. Given these findings, traditional colloid filtration theory may not be appropriate for the prediction of MWCNT mobility in porous media. This may be due to the large aspect ratio of the MWCNTs and the importance of straining in MWCNT removal. Additionally, we have fully characterized the uptake and depuration behaviors of single- and multi-walled carbon nanotubes with aquatic worms (Lumbriculus variegatus) and earthworms (Eisenia foetida). For both organisms, we found that the nanotubes measured in the organisms appeared not to be absorbed into the organisms’ tissues and were instead present as soil or sediment in the guts of the organisms that had not yet been purged. We also modified multi-walled carbon nanotubes with an aggressive acid mixture that was shown to dramatically increase the presence of functional groups on the nanotubes. Surprisingly, this modification did not influence their uptake and depurations behaviors by either the earthworms or aquatic worms. This modification did, however, change the nanotubes octanol-water distribution behaviors, a parameter that is commonly used with related descriptive models to predict the bioaccumulation capacity of hydrophobic organic chemicals. These results thus suggests that such an approach is not appropriate for predicting the bioaccumulation capacities of carbon nanomaterials with varying physicochemical properties, a finding with significant implications for environmental engineers and scientists involved with risk assessment. Given the minimal uptake of carbon nanotubes by earthworms and aquatic worms, we have begun to explore the mechanism behind this phenomenon. One approach has been to test the cellular assimilation rates of carbon nanotubes by HeLa cells, a widely used epithelial cell from a carcinoma cell line. Results obtained using these cells are expected to indicate the expected cellular interactions of carbon nanotubes with other environmentally critical cells such as the epithelial cells in organism’s digestive tracts. Another possible cause of minimal absorption by the organisms is strong attachment of the nanotubes to organic matter in the soil or sediment. As such, we are also testing the uptake and depuration behaviors of nanotubes by the water flea Daphnia magna in the absence of sediment. To date, we have found some very different behaviors which we are currently trying to elucidate through additional experiments.

Expected Results:

The proposed study will provide: a) fundamental information regarding carbon nanotube dispersion states, transport, fate, and bioavailability in different environmental systems; b) identify factors controlling these environmental behaviors; and c) establish deterministic models capable of predicting behaviors under different environmental conditions. This information is critically needed by EPA and the research community for rigorous assessments of the environmental fate, transport, and ecological risks of carbon nanotubes in various soil/water/sediment systems.


Journal Articles on this Report : 10 Displayed | Download in RIS Format

Other project views: All 14 publications 10 publications in selected types All 10 journal articles
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Journal Article Liu X, O'Carroll DM, Petersen EJ, Huang Q, Anderson CL. Mobility of multiwalled carbon nanotubes in porous media. Environmental Science & Technology 2009;43(21):8153-8158. R833321 (2007)
R834094 (Final)
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  • Journal Article Petersen EJ, Huang Q, Weber Jr WJ. Bioaccumulation of radio-labeled carbon nanotubes by Eisenia foetida. Environmental Science & Technology 2008;42(8):3090-3095. R833321 (2007)
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  • Journal Article Petersen EJ, Huang Q, Weber WJ Jr. Ecological uptake and depuration of carbon nanotubes by Lumbriculus variegatus. Environmental Health Perspectives 2008;116(4):496-500. R833321 (2007)
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  • Journal Article Petersen EJ, Akkanen J, Kukkonen JVK, Weber Jr WJ. Biological uptake and depuration of carbon nanotubes by Daphnia magna. Environmental Science & Technology 2009;43(8):2969-2975. R833321 (2007)
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  • Journal Article Petersen EJ, Pinto RA, Landrum PF, Weber Jr WJ. Influence of carbon nanotubes on pyrene bioaccumulation from contaminated soils by earthworms. Environmental Science & Technology 2009;43(11):4181-4187. R833321 (2007)
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  • Journal Article Petersen EJ, Huang Q, Weber Jr. WJ. Relevance of octanol-water distribution measurements to the potential ecological uptake of multi-walled carbon nanotubes. Environmental Toxicology and Chemistry 2010;29(5):1106-1112. R833321 (2007)
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  • Journal Article Petersen EJ, Pinto RA, Zhang L, Huang Q, Landrum PF, Weber Jr. WJ. Effects of polyethyleneimine-mediated functionalization of multi-walled carbon nanotubes on earthworm bioaccumulation and sorption by soils. Environmental Science & Technology 2011;45(8):3718-3724. R833321 (2007)
    R834094 (Final)
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  • Journal Article Petersen EJ, Pinto RA, Mai DJ, Landrum PF, Weber Jr WJ. Influence of polyethyleneimine graftings of multi-walled carbon nanotubes on their accumulation and elimination by and toxicity to Daphnia magna. Environmental Science & Technology 2011;45(3):1133-1138. R833321 (2007)
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  • Journal Article Shi X, Wang SH, Shen M, Antwerp ME, Chen X, Li C, Petersen EJ, Huang Q, Weber Jr WJ, Baker Jr JR. Multifunctional dendrimer-modified multiwalled carbon nanotubes: synthesis, characterization, and in vitro cancer cell targeting and imaging. Biomacromolecules 2009;10(7):1744-1750. R833321 (2007)
    R834094 (Final)
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  • Journal Article Tervonen K, Waissi G, Petersen EJ, Akkanen J, Kukkonen JVK. Analysis of fullerene-C60 and kinetic measurements for its accumulation and depuration in Daphnia magna. Environmental Toxicology and Chemistry 2010;29(5):1072-1078. R833321 (2007)
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  • Supplemental Keywords:

     , Health, Scientific Discipline, PHYSICAL ASPECTS, Health Risk Assessment, Risk Assessments, Biochemistry, Physical Processes, biological pathways, bioavailability, exposure, nanotechnology, carbon fullerene, human exposure, nanomaterials, toxicologic assessment, nanoparticle toxicity, human health risk

    Progress and Final Reports:

    Original Abstract
  • 2008
  • Final