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

动机：胶体运输在水环境中的生物地球化学循环中起着至关重要的作用。与此同时，工程纳米颗粒、微塑料和纳米塑料(MNPs)以及天然胶体(如病毒、病原菌或重金属)的本地和远程运输对人类和环境健康构成持续威胁。加拿大人每年丢弃世界上近1%的塑料，废物管理不善导致环境中随处可见的MNPs。我们目前对这些胶体在环境中的传输和相互作用缺乏了解，这突显了人们对淡水中MNP污染的释放和影响的关注。一旦颗粒进入环境水域，就会发生风化变化，从而改变其物理和化学特性--包括颗粒大小、形状和吸附能力--这使得理解MNP的命运和影响变得复杂。科学方法：大多数与环境相关的塑料都不是原始的球体，尽管目前关于形状不规则、风化的MNPs(WMNPs)与原始对应物的不同之处的信息有限。这项研究将产生和研究wMNPs的聚集、沉积和生态毒性。将使用单独和组合的氧化、热和机械条件对塑料风化过程进行详细分析，以了解它们对自然水域中MNP风化的相对贡献。然后，这项研究的产品将被用于调查wMNP在地表水和地下水中的去向和迁移。此外，尽管大多数研究表明急性毒性很小，但行为或生殖变化等慢性影响几乎完全未知。这项工作将专门研究wMNPs对大型水蚤的亚致死影响，大型水蚤是一个重要的哨兵物种。预期结果和好处：这项建议解决了在转化、运输和毒性方面的关键知识差距，这些知识差距已在加拿大环境和气候变化组织编制的《加拿大塑料科学议程》中得到强调。鉴于环境中已经存在wMNPs，我们需要更好地了解这些新出现的污染物的命运和不利影响。要做到这一点，第一步是发展产生持续风化颗粒的能力，这将为整个研究计划和其他实验室的研究提供基准。然后，了解胶体和表面的基本相互作用如何影响wMNP的运输和影响，将有助于改善对水生野生动物和水资源的保护。将在水处理调查中利用导致聚集、沉积和絮凝的条件，以限制人类接触wMNPs并改善公众健康。最终，研究模式生物体中MNPs的亚致死影响将有助于决策者制定适当的、知情的风险评估和管理战略。

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.