National Exposure Research Laboratory, Exposure Methods & Measurement Division (GA)
This research focuses on environmental transformations of nanomaterials and inactivation of pathogen indicators. To develop predictive assessments of the impacts of human activities on water quality and ecosystem health, our goal is to understand mechanisms for these transformations and to develop procedures for predicting their rates under differing environmental conditions. Current areas of emphasis include photochemical and microbial dynamics of organic and metallic engineered nanomaterials (ENMs), such as carbon nanomaterials, including graphene-based materials, release of engineered nanomaterials from polymer nanocomposites and other matrices that are commonly used in ENM formulations, and providing parameters and process relationships for modeling exposure to ENMs. The research includes elucidation of reactive oxygen species that mediate photochemical cycling and adverse effects of nanomaterials, UV effects on virulent organisms (bacteria, protozoa, viruses) and bacterial or bacteriophage indicators, and effects of natural organic matter, sediments, and soils on nanomaterial and pathogen transformations in the environment. Equipment, including solar simulators and weathering simulators, irradiance sensors, chromatographs, carbon analyzers, FTIR and UV-visible spectrometers, are available for these studies. Laboratory facilities include the equipment required for these studies with instrumentation to measure nanomaterial and sediment concentrations and size distributions, bacterial and bacteriophage concentrations (including qPCR), spectral properties of nanomaterials (FTIR, UV-visible, excitation-emission matrix fluorometry, and chromatographs), spectrometers for elucidating carbon transformation products. Access to ICP-MS, TEM, and SEM is also available for characterizing ENMs, their composites, and transformation products. Facilities for solar simulation and measurements of quantum yields and action spectra are available for photochemical and photobiological studies.
Transformations; Nanomaterials fate; Photoreactions; Photoinactivation; Pathogen decay; Natural organic matter;