Microplastics and other Anthropogenic Contaminants: from Source to Sink in the Canadian Environment

Anthropogenic particles (AP), including microplastics and microfibers, are a ubiquitous contaminant in the environment. Due to the mounting evidence of their persistence, accumulation and toxicity, the sources, release pathways and fate of AP warrant further investigation in order to identify and develop effective mitigation efforts. This thesis aims to (1) investigate the abundance and composition of AP assemblages in environmental sinks, (2) explore environmental transport pathways for AP in the Canadian environment, (3) assess AP sources and release pathways; and (4) explore opportunities for diverting these releases to the environment. This thesis documents anthropogenic microfibers, including those composed of natural and semi-synthetic materials, as a major component of AP contamination in the Canadian environment. Further, this work shows, for the first time, that fractionation of AP occurs as particles are transported from sources to remote environments. Evidence from sediment samples indicates that fractionation occurs such that microfibers, particularly those composed of anthropogenically-derived natural and semi-synthetic materials, undergo long-range transport to remote areas whereas, non-fibrous particles tend to settle closer to source regions. As a result, microfibers from blue jeans, the world’s most popular garment, have similar abundance in Arctic sediments as in sediments from populated urban source regions. This work provides further evidence supporting the use of washing machine filters for mitigating microfiber emissions from laundering. This thesis also shows that secondary, external dryer filters can be an effective means for diverting releases of microfibers during laundering. By expanding investigation to include semi-synthetic and natural textile fibers and advancing methods for the confident enumeration and identification of microfibers in environmental samples, this thesis has led the shift in our scientific understanding of what constitutes AP contamination, and specifically microfiber pollution.