Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments

Abstract

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. In Humber Bay and Toronto Harbour microplastic concentrations were consistently >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 < 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 . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Ballent, Anika Manuscript page 1Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments. AbstractMicroplastics 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. In Humber Bay and Toronto Harbour microplastic concentrations were consistently >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 < 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.

Distribution and Modeled Transport of Plastic Pollution in the Great Lakes, the World's Largest Freshwater Resource

“…According to this model, most of the floating plastics sampled in the western and central basin would have been in Lake Erie for <2 years. However, while most virgin plastic used in consumer products-especially one-time use plastic (PlasticsEurope: Association of Plastics Manufacturers, 2015)-is predicted to be positively buoyant, plastic litter is readily found in sediment (Corcoran et al, 2015;Ballent et al, 2016). This can be attributed to denser polymer types sinking, but there are other dynamic changes in the buoyant density that plastics are likely to undergo once in the environment, e.g., oxidation or biofouling.…”

“…Field surveys have confirmed the presence of microplastics in Great Lakes surface water (Eriksen et al, 2013;Mason et al, 2016), sediment (Corcoran et al, 2015;Ballent et al, 2016), and beaches (Zbyszewski and Corcoran, 2011;Hoellein et al, 2014;Zbyszewski et al, 2014;Driedger et al, 2015), as well as the rivers (Baldwin et al, 2016) and wastewater treatment plant (WWTP) effluents (Michielssen et al, 2016) that directly feed into the Great Lakes. Yet, these data are sparse.…”

Micro- and Nanoplastic Pollution of Freshwater and Wastewater Treatment Systems

“…In America, most research has concentrated in Canada and the USA, ( Fig. 2; Online Resource 1), particularly in the Great Lakes area [6,18,26,80,96,97], including the St. Lawrence River watershed [12]. Of these, only two studies collected data from freshwater bottom sediments [12,18], and one considered open-water loading (the Laurentian Great Lakes system) [26].…”

Secondary microplastics were prevalent in sediment in a freshwater UK urban river

“…black or dark blue, light blue, and red). Micro-fibres of similar characteristics 337 were observed in other freshwater ecosystems (Ballent et al, 2016), where fibres <2 mm identified 338 visually with a stereo microscope were found to be the predominant type of MPs, alongside fragments 339 in the same size range. In the River Kelvin sediment, fibres were observed in isolation, in clusters and 340 embedded in sediment grains (Fig.…”

“…5). Similarly, others have reported the predominance of fibres (Ballent et al, 2016;Su et al, 2016), 358 especially in systems associated with wastewater treatment as such fibres typically break off synthetic 359 textiles and are released via household sewage (Browne et al, 2011;Magnusson and Nóren, 2014).treatment facility, it has been suggested that fibres can be transported for greater distances (Ballent et 362 al., 2016), thus their presence may be attributed to distant inputs upstream from the study site. 363…”