Microplastics and plastic additives in the St. Lawrence River and Estuary: occurrence, fate and impacts

微塑料（MPs）被定义为直径小于5毫米的塑料碎片，已知被野生动物和人类摄入。摄入和接触微塑料可能导致不利影响，包括与塑料相关的化学品（如塑料添加剂）有关的物理损伤和毒性。然而，我们对MPs和塑料添加剂在环境中的分布、移动、反应和行为的了解非常有限。因此，加拿大政府的塑料污染科学评估草案将MPs污染确定为研究重点。在加拿大，现有的对MPs和塑料添加剂的监测活动主要集中在劳伦森大湖和北极，而这些污染物在其他生态系统中的状况在很大程度上仍然未知。圣劳伦斯河和河口（SLRE）拥有一套独特的生态系统，但也构成了大西洋污染物的载体。鉴于SLRE是加拿大的优先生态系统之一，位于劳伦森五大湖下游，是500多万加拿大人的家园，缺乏该地区塑料污染的数据阻碍了对这一重要系统的影响和管理策略的优先级。为了解决这些知识空白，该项目将调查(1)来自SLRE的大气沉积物、空气颗粒、地表水和生物群（鱼类和鸟类）中MPs和塑料添加剂的发生和特征；(2)水中MPs光降解过程中温室气体的排放和塑料添加剂的浸出；(3) MPs的固有光学特性及其遥感应用；(4) MPs相关化学物质的野生动物生态毒理学研究。由于各种塑料在工业和商业产品中有不同的应用，了解MPs的组成可以帮助确定主要来源并制定合理的管理方法。因此，本研究获得的结果将对加拿大范围内的零塑料废物战略具有很高的价值，可以识别风险并提供有效的对策。

Microplastics (MPs) are defined as plastic fragments with a diameter less than 5 mm, which are known to be ingested by wildlife and humans. Ingestion of and exposure to microplastics may lead to adverse effects, including physical damage and toxicity related to plastics-associated chemicals (e.g., plastic additives). However, our knowledge about how MPs and plastic additives distribute, move, react and behave in the environment is very limited. Therefore, MPs pollution has been identified as a research priority by the Canadian government's Draft Science Assessment of Plastic Pollution. In Canada, the existing monitoring activities for MPs and plastic additives have centred on the Laurentian Great Lakes and the Arctic, and the status of these contaminants in other ecosystems remains largely unknown. The St. Lawrence River and Estuary (SLRE) host a suite of unique ecosystems but also constitute a vector of contaminants to the Atlantic Ocean. Given that the SLRE is one of Canada's priority ecosystems, is downstream from the Laurentian Great Lakes, and is home to more than 5 million Canadians, the lack of data on plastic pollution in the region impedes understanding effects on this important system and prioritization of management strategies. To address these knowledge gaps, this project will investigate (1) the occurrence and characteristics of MPs and plastic additives in atmospheric depositions, air particles, surface water, and biota (fish and bird) from the SLRE; (2) emissions of greenhouse gases and leaching of plastic additives during the photodegradation of MPs in water; (3) the inherent optical properties of MPs and their remote sensing applications; and (4) wildlife ecotoxicology of chemicals associated with MPs. Since the various plastics have different applications in industrial and commercial products, understanding the composition of MPs could help identify major sources and develop rational approaches for their management. Thus, the results obtained in this research will be highly valuable for the Canada-wide strategy on zero plastic waste to identify risks and provide effective countermeasures.