Distribution of Microplastics in Benthic Sediment of the Thames River, Ontario

Session: 46. - Plastics in the Great Lakes: Characterizing the Problem and Finding Solutions

Patricia Corcoran, University of Western Ontario, [email protected]
Sara Belontz, Western University , [email protected]
Paul Helm, Ontario Ministry of the Environment and Climate Change, [email protected]
Kelly Ryan, University of Western Ontario, [email protected]

Abstract

Microplastics have been documented in surface waters, but relatively little information is available concerning microplastics in benthic zones. The 400 km long Thames River system in Ontario, Canada offers an opportunity to investigate the influence of grain size as well as agricultural and urban influences on microplastics deposition. The Thames River system, divided into the upper, middle and lower Thames and the Thames River proper,empties into Lake St. Clair in the Laurentian Great Lakes system. Thirty-four samples were collected from river bottom sediment using a petite ponar grab in November and December, 2016. Sample splits were processed for grain size analysis and density separation. A total of 1841 microplastic particles were identified with a range of 16 to 7075 pieces per kilogram of dry weight sediment. Microplastic types were fibers (69%), fragments (28%), and beads (3%). The initial bead count was significantly higher, but Scanning electron microscopy-Energy dispersive X-ray spectroscopy (SEM-EDX) indicated that only 17% of the beads analyzed contained carbon. The most abundant fragments were blue and red, whereas fibers were mainly blue and black. Microplastics were most abundant in fine sediment (<0.125 mm) and the greatest particle counts were recorded in samples near or in urban areas. 

1. Keyword
microplastics

2. Keyword
bottom sampling

3. Keyword
Great Lakes basin

4. Additional Keyword
Thames River