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

研究动机：胶体迁移在水环境中的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、微米和纳米塑料（MNP）以及天然胶体（如病毒、病原菌或重金属）的局部和远距离运输对人类和环境健康构成持续威胁。加拿大人每年扔掉世界上近1%的塑料，废物管理不善导致MNP在环境中无处不在。我们目前对这些胶体在环境中的运输和相互作用缺乏了解，这凸显了人们对MNP污染在淡水中的释放和影响的担忧。一旦微粒进入环境沃茨，就会发生风化变化，改变其物理和化学特性，包括微粒大小、形状和吸附能力，这使了解MNP的归宿和影响变得复杂。 科学方法：大多数与环境相关的塑料都不是原始球体，尽管目前的信息有限，不规则形状的风化MNP（wMNP）与其原始对应物有何不同。这项研究将产生和研究wMNP的聚集，沉积和生态毒性。塑料风化过程的详细分析将使用单独的和组合的氧化，热和机械条件，以了解它们的相对贡献MNP风化在自然沃茨。本研究的结果将用于调查wMNP在地表沃茨和地下沃茨中的归宿和迁移情况。此外，虽然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。这项工作将专门调查亚致命的影响wMNPs在大型蚤，一个重要的哨兵物种。 预期成果和益处：该提案涉及加拿大环境和气候变化部编写的加拿大塑料科学议程中强调的关于转化、运输和毒性的关键知识差距。鉴于wMNP已经存在于环境中，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。第一步是开发生产一致风化颗粒的能力，这将为整个研究计划和其他实验室的研究提供基准。然后，了解基本的胶体和表面相互作用如何影响wMNP的运输和影响，将导致改善水生野生动物和水资源的保护。导致聚集，沉积和絮凝的条件将在水处理研究中得到利用，以限制人类暴露于wMNP并改善公众健康。最后，在模式生物中观察MNP的亚致死影响将支持政策制定者制定适当的，明智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.