Basin-wide Analysis of Microplastics in Nearshore and Offshore Benthic Sediments of Lake Huron

Session: Microplastics in Freshwater Systems: Advances in Chemistry, Biology and Physics (2)

Sara Belontz, University of Western Ontario, [email protected]
Patricia Corcoran, University of Western Ontario, [email protected]
Paul Helm, Ontario Ministry of the Environment, Conservation and Parks, [email protected]

Abstract

Microplastics have been identified in river bottom, nearshore benthic, and shoreline sediment of the Laurentian Great Lakes, demonstrating that sand and silt are significant sinks for deposition of synthetic particles. In order to better understand the factors controlling abundance, transport, and deposition of microplastics within Lake Huron, physiological features including water circulation, depth, and complex bathymetry will be investigated and compared to microplastic morphology and composition. This study will provide the first comprehensive analysis of benthic microplastics across the entirety of one of the Great Lakes. To date, microplastics have been extracted from 92 nearshore and offshore benthic sediment samples using a 1.5 g/cm³ density separation solution of Sodium Polytungstate (SPT). Microplastic particles from 14 Georgian Bay samples have been visually identified and counted using a stereomicroscope. Preliminary results reveal offshore depositional sites contain greater average abundances of microplastics with 159 g^-1 (number of particles per g of dry weight sediment), compared to 34 g^-1in nearshore sites. Representative particles will be chemically analyzed by Fourier Transform Infrared Spectroscopy. Results will enable assessment of current and future trends in microplastic abundance in the Lake Huron basin.