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

微塑料(MPS)是指直径小于5毫米的塑料碎片，已知可供野生动物和人类摄取。摄入和接触微塑料可能会导致不良影响，包括与塑料有关的化学品(例如塑料添加剂)造成的身体损害和毒性。然而，我们对MPS和塑料添加剂在环境中如何分布、移动、反应和行为的了解非常有限。因此，MPS污染已被加拿大政府的塑料污染科学评估草案确定为研究重点。在加拿大，对多氯联苯和塑料添加剂的现有监测活动集中在劳伦斯五大湖和北极，这些污染物在其他生态系统中的状况在很大程度上仍不清楚。圣劳伦斯河和河口(SLRE)拥有一套独特的生态系统，但也构成了污染物进入大西洋的媒介。鉴于SLRE是加拿大的优先生态系统之一，位于劳伦斯五大湖的下游，是500多万加拿大人的家园，该地区缺乏关于塑料污染的数据，阻碍了对这一重要系统的影响的了解和管理战略的优先次序。为弥补这些知识空白，本项目将调查(1)可持续发展区域大气沉积物、空气颗粒、地表水和生物群(鱼和鸟)中MPS和塑料添加剂的存在和特征；(2)MPS在水中的光降解过程中温室气体的排放和塑料添加剂的淋溶；(3)MPS的固有光学性质及其遥感应用；以及(4)与MPS相关的化学品的野生动物生态毒理。由于各种塑料在工业和商业产品中的应用不同，了解MPS的组成有助于确定主要来源并制定合理的管理方法。因此，这项研究的结果将对加拿大范围内的零塑料垃圾战略识别风险并提供有效的对策具有很高的价值。

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.