Transatlantic Initiative for Nanotechnology and the Environment

We have developed a life cycle perspective inspired conceptual model (CM) that suggests the importance of terrestrial ecosystems as a major repository of ZnO, TiO2, and Ag (Tier 1) manufactured nanomaterials (MNMs) introduced via the land application of MNM-containing biosolids. We propose to investigate the transport, fate, behavior, bioavailability, and effects of MNMs in(to) agroecosystems under environmentally realistic scenarios organized around three key hypotheses: Hypothesis (H1) Surface chemistry is the primary factor influencing the fate and transport of MNMs in the terrestrial environment as well as the bioavailability and effects to biological receptors; Hypothesis (H2) Once released to the environment, pristine MNM surfaces will be modified by interactions with organic and inorganic ligands (macromolecules) or via other biogeochemical transformations (aging effects forming a-MNMs); Hypothesis (H3) Ecoreceptors will respond to interactions with pristine metal and metal oxide MNMs, a-MNMs, and/or dissolved constituent metal ions and bulk oxides by specific ecological and toxicogenomic responses that will reflect their combined effects. Experimental Approach: Detailed physicochemical characterization will be conducted on Tier 1 and Tier 2 (CeO2, carbon nanotubes) MNMs and a-MNMs produced by simulating aging and these materials will be utilized in column transport (Tier 1 and 2), bioavailability, and effects (Tier 1) studies to key ecoreceptors (bacteria, soil invertebrates, and plants). Data needed to calibrate and validate the pBRM will be collected for Tier 1 MNMs using a subset of ecoreceptor species. The CM and model results from the simulated aging of MNMs will then be validated by repeating studies of Tier 1 MNMs subjected to actual WWTP using a pilot scale WWT facility. To facilitate these and future investigations of MNMs under environmentally relevant scenarios, novel in situ tools will be developed. Expected Results: The proposed research will generate among the first data on the transformations of important classes of MNMs subjected to WWTP as well as those added to and aged in soil. These data will be critical for evaluating potential direct and indirect ecological and human health risks of MNMs introduced to agroecosystems. Data generated on the simulated aged materials and on the MNM containing biosolids and soils to test H1 & H2, may indicate that the permutations of MNM properties required to be experimentally considered under realistic environmental scenarios can be significantly reduced. Furthermore, the results of this work will provide the first validation of using gene and protein expression profiles generated in laboratory controlled experiments as an indicator of exposure or effects under environmentally realistic conditions. An important output from the proposed research and modeling efforts will be the development of first generation validated predictive models of the environmental fate, behavior, bioavailability, and effects of several important classes of MNMs in agroecosystems.