You are here:
Simulating Multiwalled Carbon Nanotube Transport in Surface Water Systems Using the Water Quality Analysis Simulation Program (WASP)
Citation:
Bouchard, D., Chris Knightes, X. Chang, AND B. Avant. Simulating Multiwalled Carbon Nanotube Transport in Surface Water Systems Using the Water Quality Analysis Simulation Program (WASP). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 51(19):11174–11184, (2017).
Impact/Purpose:
The unique electronic, mechanical, and structural properties1-3 of carbon nanotubes (CNTs), their potential in drug delivery and other biomedical applications,4,5 as well as utilization in polymer composites,6 has led to increasing production of these versatile materials. In a 2014 report, the President’s Council of Advisors on Science and Technology (PCAST) identified engineered nanomaterials as substantial components of future global economic activity.7 There are currently more than 1,600 consumer products reported to contain nanoscale materials; and the use of carbon-based nanomaterials (fullerenes, CNTs, and graphene family materials) in these products trails only nano-scale silver and titanium.8 Carbon-based nanomaterials are also referenced in 40% of the nanotechnology patent applications submitted to the US Patent and Trademark Office from 1/2010–3/2011,9 and upper estimates for US CNTs production are in excess of 1000 tons per year.10 Clearly, as more CNTs are produced and utilized in commerce, the potential for either permitted or accidental releases increases; and, concomitantly, the potential for human and ecological exposures also increases.11,12 These potential exposures underscore the importance of developing models for simulating CNT transport and transformation in the environment.
Description:
Under the Toxic Substances Control Act (TSCA), the Environmental Protection Agency (EPA) is required to perform new chemical reviews of nanomaterials identified in premanufacture notices. However, environmental fate models developed for traditional contaminants are limited in their ability to simulate nanomaterials’ environmental behavior by incomplete understanding and representation of the processes governing nanomaterial distribution in the environment and by scarce empirical data quantifying the interaction of nanomaterials with environmental surfaces. In this study, the well-known Water Quality Analysis Simulation Program (WASP) was updated to incorporate particle collision rate and particle attachment efficiency to simulate multiwalled carbon nanotube (MWCNT) fate and transport in surface waters. Heteroaggregation attachment efficiencies (αhet) values derived from sediment attachment studies are used to parametrize WASP for simulation of MWCNTs transport in Brier Creek, a coastal plain river located in central eastern Georgia, and a tributary to the Savannah River. Simulations using a constant MWCNT load of 0.1 kg d–1 in the uppermost Brier Creek water segment showed that MWCNTs were present predominantly in the Brier Creek water column, while downstream MWCNT surface and deep sediment concentrations exhibited a general increase with time and distance from the source, suggesting that MWCNT releases could have increasing ecological impacts in the benthic region over long time frames.
