Browsing by Subject "Microplastics"

Now showing 1 - 2 of 2
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    A Comparison of The Microplastic Burden on the Ecosystems of Four Inland Lakes in Minnesota, USA
    (2022) Conowall, Peter
    Microplastic (plastic particles < 5mm) pollution has potentially detrimental impacts on aquatic and marine ecosystems. Here we examine the extent of microplastic pollution in four small inland lakes in Minnesota, USA (Elk, Peltier, Ten Mile, and White Iron Lakes), which represent a range of human impacts, as well as a variety of watershed and lake characteristics. Surface water particulates, benthic sediments, and filter and visual feeding fish were collected in the summers of 2019 and 2020 to examine the loading of microplastics into these lakes and their distribution within these ecosystems. Results show that catchment area and urban development were the most influential factors on microplastic loading. Surface water microplastic concentrations ranged from 16,000 microplastics km-2 in Elk Lake to 150,000 microplastics km-2 in White Iron Lake, comparable to concentrations from very remote lakes (Lake Hovsgol, Mongolia, 20,264 microplastics km-2) to more anthropogenically influenced lakes (Lake Erie, USA, 105,500 microplastics km-2) (Eriksen et al., 2013; Free et al., 2014). The concentrations in benthic sediments ranged from 14 microplastics kg-1sed in Elk Lake to 190 microplastics kg-1sed in Peltier Lake and were not directly correlated to surface water concentrations. Consumption by filter feeding fish was determined to be dependent on surface water concentrations, while consumption by visual feeding fish was not. These results indicate that differences across small aquatic ecosystems will require dynamic management of microplastic pollution.
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    Quantifying the Size Fraction of Microplastic Debris Throughout the Water Column of Western Lake Superior
    (2022-06) Schwoerer, Guenter
    Plastic pollution is a widely acknowledged global problem that has various negative impacts on the environment. As of 2019, 9.2 billion tonnes of plastic have been produced, and roughly 80% of plastic has become waste. Poor waste management, combined with the designed durability of plastics, has allowed plastic pollution to exponentially accumulate in aquatic systems. Once in the environment, plastic debris can weather and break down into smaller particles known as micro- and nano-plastics. This work determines the distribution of microplastics within different size fractions at different depths in the water column at four sites in Western Lake Superior. Samples were collected in May and August of 2021 with both manta net trawls, which collect microplastics >333 µm at the air-water interface, and McLane pumps fitted with three filter sizes to sample the water column. Microplastics were detected with visual microscopy or FTIR microscopy, depending on the size class. Our research shows that the Lake Superior water column contains large amounts of microplastic waste, with an increasing number of microplastic particles per volume as particle size decreases. As well as a decreasing number of microplastics per volume as depth increases. Additionally, the spatial distribution of microplastics in Lake Superior also seems to fluctuate throughout the year as the characteristics of the water column change seasonally. Overall, this is the first study to collect bulk samples from the water column of any Laurentian Great Lakes and the first to report the size fractionation of microplastic debris within the water column; therefore, furthering our understanding of the plastic pollution problem in the Great Lakes.