Anthropogenic particles in natural sediment sinks: Microplastics accumulation in tributary, beach and lake bottom sediments of Lake Ontario, North America

Surface waters of the Great Lakes are known to be contaminated with microplastics, however, microplastics in the sediments of the region are poorly documented. This study provides a baseline of micro- and macro-plastics contamination in nearshore, tributary and beach sediments of Lake Ontario and the upper St. Lawrence River. Microplastics were quantified and characterized by morphology and composition using visual identification and Raman spectroscopy. Microplastics are most concentrated in nearshore sediments in the vicinity of urban and industrial regions. Concentrations in Humber Bay and Toronto Harbour consistently measured \u3e 500 particles per kg dry sediment, and maximum concentrations of ~28,000 particles per kg dry sediment were quantified at Etobicoke Creek. Sourced from consumer and industrial activity, abundant plastics in Lake Ontario coastal environments are unnatural persistent contaminants warranting urgent action for the protection of benthic fauna and ecosystem health

Sources and Sinks of Microplastics in Canadian Lake Ontario Nearshore, Tributary and Beach Sediments

Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. InHumber Bay and Toronto Harbour microplastic concentrations were consistently greater than 500 particles per kg dry sediment. Maximum concentrations of ~28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments less than 2 mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring and discuss potential sources of microplastics in terms of how and where to implement preventative measures to reduce the contaminant influx. Although the impacts of microplastics contamination on ecosystem health and functioning is uncertain, understanding, monitoring and preventing further microplastics contamination in Lake Ontario and the other Great Lakes is crucial