Grant: Discovery Grants Program - Individual

This program does not involve indigenous communities, societies, or individual. The widespread occurrence of micro/nanoplastics (MNP) in the environment is of concern due to their potential for biological uptake and their capacity for contaminant adsorption. Plastic materials can generate MNP by a variety of weathering pathways, including abrasion, photooxidation by ultraviolet (UV) light, or chemical oxidation. However, the relationships between the properties of plastic materials, their potential for MNP generation, as well as the characteristics and implications of the MNP they generate are still unclear. In my Discovery (DG) program, I will use my expertise in the study of the biological and environmental interactions of materials to adress these critical knowledge gaps that limit our ability to predict the sources and impacts of MNP pollution or design safer plastic products. The specific objectives (SO) of my DG program are to (SO-1) Understand how the properties of plastic materials influence the rate of MNP generation and the characteristics of the MNP they release during weathering, (SO-2) distinguish the contributions of MNP surface properties and eco-corona formation on contaminant adsorption by MNP, and (SO-3) identify the factors influencing the toxicity of MNP to a key aquatic toxicology model. To achieve these objectives, high density polyethylene (PE), the most abundant plastic in the environment, will be specifically compounded to generate a suite of materials of known additive profiles. By changing the additive type and concentration, properties such as hardness, surface free energy, the ability to tolerate UV or chemical oxidation, and additive toxicity will be systematically evaluated. The properties of the produced plastics will be thoroughly characterized before exposing them to a range of weathering scenarios, for which the MNP generated will be quantified and characterized to understand their size, morphology, and surface characteristics. We will also use MNP with distinct size and surface chemistry (modulated by weathering or additives) to characterize contaminant adsorption in the presence and absence of the eco-corona, a layer of adsorbed proteins and organic matter that forms on MNP in the environment. These experiments will distinguish the role of the intrinsic surface properties of plastics from the eco-corona influence in the adsorption of contaminants. Finally, the properties important for the toxicity of MNP to Daphnia magna will be studied using select MNP of different weathering states and additive compositions, alone or with co-occuring contaminants and eco-corona. Altogether, my DG program will provide a multidisciplinary training environment, at the interfaces of environmental engineering, environmental chemistry, and material science, to enhance our understanding of the fate and impacts of plastic pollution as well as inform the selection of material properties for the design of safer plastic products.