Thesis Format

Monograph

Controls on Plastic Debris Capture in Urban Stormwater Drains of London, Canada: A Study Within the Great Lakes Watershed

Author

Nina KozikowskiFollow

Degree

Master of Science

Program

Geology

Supervisor

Patricia, Corcoran

Abstract

Land-based sources are the greatest contributors of plastic pollution in aquatic environments. Prior to this investigation, there were no available studies concerning the number and types of plastic debris items between 1 mm and 5 mm captured in urban stormwater drains. The present study examined macroplastic (>5 mm) and large microplastic (1-5 mm) debris that accumulated in LittaTrap^TM devices at six drain sites over four seasonal periods in London, Ontario, Canada. Macroplastics (MaPs) and microplastics (MPs) were found in all 36 samples, and the totals ranged from 5-158 MaPs and 18-359 MPs per trap. Out of the 118 different MaPs found, the most common were cigarette butts, wrappers, and expanded polystyrene. The predominant MPs were fragments, foams, and fibres. Summer samples contained the highest average amounts of plastic. The main controls on plastic debris accumulation in stormwater drains of the London core are increased pedestrian traffic, driving, and seasonal variability.

Summary for Lay Audience

The global input of plastic debris into the natural environment is mainly sourced from land-based activities. Within urban areas, plastics generated through littering, accidental spillage, and degraded infrastructure, accumulates on city streets and other impervious surfaces. During rain events, these plastic items run off into stormwater drains and eventually become deposited in natural tributaries. This study examines the possible controls on plastic debris deposition into stormwater drains of London, Ontario, Canada. Six LittaTrap^TM devices were installed in city core stormwater drains to capture macroplastic (> 5mm) and large microplastic (1-5 mm) debris during different seasons before entering the watershed. Macroplastics (MaPs) and microplastics (MPs) were found in all 36 samples, and were characterized according to abundance, size, item type, and composition. The results indicate a seasonal influence on number of items, as the winter samples on average contained the fewest plastics overall. Total precipitation and average wind speed, however, did not correlate with the amounts of plastic debris at each location. Instead, increased plastic pollution appears to be linked to increased outdoor activities during the warmer months. Plastic debris abundances also showed a positive correlation with stormwater drain location, as the highest counts were in high pedestrian areas. The three most common identifiable MaPs were cigarette butts (31.4%), wrappers (18.3%), and expanded polystyrene (3.5%). In terms of applications, “smoking”, “packaging”, and “narcotics” were most prevalent, with the latter category most common at the site where individuals were witnessed using and distributing narcotics. Fragments were the most common type of MPs, accounting for 45.0% of the total. Polymer compositions, as determined by Fourier transform infrared spectroscopy (FTIR) and a visual identification method, were mainly polyethylene and polypropylene, which are common to a large variety of products. Other polymer types, such as polybutadiene, alkyds, and polyethylene terephthalate are consistent with rubber, paints, and textiles, respectively. This study reveals that location within the downtown core is a key driver of plastic debris amounts and types, which emphasizes the urgent need for public awareness campaigns regarding land-based plastic use, fate, and reduction.

Recommended Citation

Kozikowski, Nina, "Controls on Plastic Debris Capture in Urban Stormwater Drains of London, Canada: A Study Within the Great Lakes Watershed" (2024). Electronic Thesis and Dissertation Repository. 9928.
https://ir.lib.uwo.ca/etd/9928

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.