Engineered nanomaterials (NMs) are a new class of pollutants, and debate is growing regarding their potential hazard in the environment. This proposal aims to contribute towards gaining improved information on the exposure component of hazard assessment. Even for the high production volume (HPV) NMs used today in society (TiO₂ and SiO₂) there is a paucity of field monitoring data on their concentration or frequency of occurrence in aquatic systems. Environmental monitoring of NMs on the cusp of widespread use (e.g., Ag0, CeO₂, CNT, C60, etc.) or futuristic high value-added NMs will remain unattainable unless frameworks and analytical methods exist to understand where and how to find NMs. We propose developing and applying a framework for monitoring NMs in the environment. Nanoprospecting is the first stage of this investigative framework, involving monitoring for the presence of HPV and emerging NMs at critical inputs to and points along the urban water system. Bulk food ingredients are a major potential source of NMs into the urban water system. To compliment the use of existing analytical approaches available today to detect NMs at environmentally relevant concentrations, we propose improvements to post-processing of data signals from specific instrumentation and discovering the suitability of several NM extraction techniques that leverage a unique property of NMs by exploiting the unique phenomena of NMs that a minimum free energy exists for NMs at the solvent-water or water-solid interface. By monitoring for a few NMs in the environment today, information and data can be collected and used in validating life cycle models. Research is organized around the following four research components: (1) Nanoprospecting across an urban water gradient; (2) Nanoprospecting in the food supply system; (3) Using interfaces for nanomaterial extraction from water; (4) Framework for long-term monitoring of aquatic systems for nanomaterials.

Nanoprospecting builds upon experiences of the environmental community dealing with other emerging contaminants and technologic shifts, and is complimentary to life cycle perspectives. Specifically, this project will provide the scientific community with estimates of realistic human (through food) and ecosystem (through urban water gradients) exposure levels and characteristics of "real" nanomaterials, as opposed to NMs purchased or synthesized solely for research-grade testing. New extraction methodologies and signal processing of analytical response data will be developed. The research is motivated by the following scientific questions: What is the frequency in detection of nanomaterials across the urban water gradient? What are the occurrences and characteristics of nanoscale TiO₂ and SiO₂ in bulk food ingredients and finished food products? How can the unique property that nanoscale objects adsorb at liquid or solid interfaces be harnessed to extract nanomaterials from water and facilitate their characterization? Could a monitoring framework and network of monitoring stations be established to provide baseline and longer-term data on nanomaterials in water?

By focusing on field-scale monitoring we hope to lead the environmental nanotechnology field toward establishing protocols suitable for monitoring NMs at environmentally relevant concentrations. The researchers have a proven commitment to mentoring gender and ethnically iverse undergraduate and graduate students. The graduate student funded by this project will participate in Science Outside the Lab, a two-week immersive seminar in Washington, DC that explore how science becomes policy. The project connects with the NSF Central-Arizona Phoenix Long Term Ecological Research (CAP LTER) program, taking a similar longitudinal approach looking at NMs along the urban water gradient, and field data collected by this project will become part of the CAP LTER data archives. The research team has a record of onducting research of interest and visible to the public, and will continue to strive to share our results with the public, including working with the Center for Nanotechnology in Society at ASU.