Temporal/Spatial Trends and Concentrations of Microplastics in Streams Throughout the Central Illinois Watersheds

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Geography, Geology and the Environment


Catherine O'Reilly

Mentor Department

Geography, Geology and the Environment


Daily activities, like washing clothes, using soap, industrial cleaning use, etc., introduce potenially dangerous [OC1] microplastics into our freshwater systems. These plastic particles are defined by their size, which is <5mm in diameter. Throughout cities across the United States, local municipalities have to treat their household and industrial sewage water at WWTP's (Waste Water Treatment Plants) in order for it to be released back into the environment. In many instances, WWTP effluent has been recorded to contain microplastics. WWTP's can be seen as a mechanism where high concentrations of microplastics can be focused into our water sources. There are currently no policies or regulations requiring treatment plants to treat for microplastics. Microplastic particles have been known to carry bacteria assemblages that cause gastrointestinal infections as well as leaching PCB (polychlorinated biphenyl) which has been known to cause health risks like cancer and infertility in humans . Due to the relatively unstudied side effects that these particles can have on humans, it is important to identify the sources of microplastics and to reduce them into our environment. Within the central Illinois watersheds there are a multitude of WWTP's. By studying effluent from WWTP's, we can begin to understand how microplastics are derived in the treatment process. Current microplastic studies have been focused on very large urban populations like Chicago and large bodies of water like the Great Lakes. Little attention has been focused on small scale watersheds and streams within central Illinois as well as watersheds throughout the United States. By examining water samples upstream and downstream from WWTP's, I can determine if microplastics are being produced by WWTP's. This study is not limited to the central Illinois watershed or to WWTP's, the methods used in my study can be applied to any watershed where flowing surface water is present. Do higher populated urban areas within the central Illinois watershed have a larger concentration of microplastics than less populated areas? The cities of Bloomington-Normal, Clinton, Champaign-Urbana have a population of 130,000, 7,200, and 120,000 respectively and all use WWTP's to treat household and industrial sewage. I conclude that Bloomington-Normal will have the highest concentration of microplastics based on its higher population. This is expected since there are more people and more household sewage would have to be treated at WWTP's.



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