Citation:

Avant, B., Chris Knightes, D. Bouchard, X. Chang, Matt Henderson, AND R. Zepp. Modeling Engineered Nanomaterials (ENMs) Fate and Transport in Aquatic Ecosystems. Georgia Water Resources Conference, Athens, GA, April 19 - 20, 2017.

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Presented at the Georgia Water Resources Conference.

Description:

Under the Toxic Substances Control Act (TSCA), the Environmental Protection Agency (EPA) is required to perform new chemical reviews of engineered nanomaterials (ENMs) identified in pre-manufacture notices. However, environmental fate models developed for traditional contaminants are limited in their ability to simulate the environmental behavior of nanomaterials due to 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. We have updated the Water Quality Analysis Simulation Program (WASP), version S, to incorporate nanomaterials as an explicitly simulated state variable. WASPS now has the capability to simulate nanomaterial fate and transport in surface waters and sediments using heteroaggregation, the kinetic process governing the attachment of nanomaterials to particles and subsequently ENM distribution in the aqueous and sediment phases. Unlike dissolved chemicals which use equilibrium partition coefficients, heteroaggregation consists of a particle collision rate and an attachment efficiency ( lXhet) that generally acts as a one direction process. To demonstrate, we used a derived a het value from sediment attachment studies to parameterize WASP for simulation of multi walled carbon nanotube (MWCNT) transport in Brier Creek, a coastal plain river located in central eastern Georgia, USA and a tributary to the Savannah River. Simulations using a constant MWCNT loadof 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 MWCNTs accumulated in sediments attached to different naturally occurring particulates. Distribution ofMWCNTs in the sediment layer followed the distribution of sediment particles. Downstream MWCNT surface sediment concentrations exhibited a general increase with time and distance from source. With the increasing production of nanomaterials, the development of WASPS for nanomaterials provides a powerful tool for investigating ecological exposure to these potential contaminants.

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