Investigating colloidal interactions to improve knowledge of transformations, transport, and impacts of micro- and nanoplastics in environmental freshwaters

点击翻译按钮获取中文摘要

Motivation: Colloidal transport plays a vital role in biogeochemical cycling in the aquatic environment. Meanwhile, local and long- range transport of engineered nanoparticles, micro- and nanoplastics (MNPs), and natural colloids such as viruses, pathogenic bacteria, or heavy metals present ongoing threats to human and environmental health. Canadians throw away nearly 1% of the world's plastic annually, and waste mismanagement contributes to the ubiquity of MNPs in the environment. The concern surrounding the release and impacts of MNP pollution in freshwaters is underscored by our current lack of knowledge of the transport and interactions of these colloids in the environment. Understanding MNP fate and impact is complicated by the weathering transformations that take place once particles enter environmental waters which will change their physical and chemical characteristics - including particle size, shape, and sorption capacity. Scientific Approach: Most environmentally relevant plastics are not pristine spheres, although information is currently limited in how irregularly shaped, weathered MNPs (wMNPs) differ from their pristine counterparts. This research will produce and study the aggregation, deposition, and ecotoxicity of wMNPs. A detailed analysis of the plastic weathering process will be performed using separate and combined oxidative, thermal, and mechanical conditions to understand their relative contribution to MNP weathering in natural waters. The products of this study will then be used to investigate wMNP fate and transport in surface waters and groundwaters. Furthermore, while most studies suggest acute toxicity is minimal, chronic effects such as changes in behavior or reproduction are almost completely unknown. This work will specifically investigate sublethal impacts of wMNPs in Daphnia magna, an important sentinel species. Anticipated Outcomes and Benefits: This proposal addresses critical knowledge gaps on transformations, transport, and toxicity that have been highlighted in Canada's Plastic Science Agenda, prepared by Environment and Climate Change Canada. Given that wMNPs already exist in the environment, we need to better understand the fate and adverse impacts of these emerging pollutants. The first step to this is developing the ability to produce consistently weathered particles that will provide a benchmark for studies both across this research program and in other labs. Then, understanding how fundamental colloidal and surface interactions influence wMNP transport and impact will lead to improved protection of aquatic wildlife and water resources. The conditions that lead to aggregation, deposition, and flocculation will be leveraged in water treatment investigations in order to limit human exposure to wMNPs and improve public health. Ultimately, looking at the sublethal impacts of MNPs in model organisms will support policy makers in developing appropriate, informed strategies for risk assessment and management.