SUSPENDED MICROPLASTICS IN AN IDAHO MOUNTAIN STREAM

Microplastics (i.e. plastic particles < 5mm) are a growing pollutant of concern resulting from the disposal and breakdown of consumer products and industrial waste. Recognized as an emerging environmental contaminant, microplastics are capable of harming aquatic organisms and entering the food web (Kapp, 2018 & Talbot, 2022). While microplastic research has primarily focused on marine environments, the rising concentration of microplastics in freshwater and terrestrial environments is becoming more apparent (Horton et.al, 2017). The objective of our research was to assess the distribution and abundance of microplastics in Idaho’s waterways, focusing on the Dry Creek watershed. A tributary to the Boise River draining a section of the Boise Foothills, Dry Creek is predominantly influenced by snowmelt runoff and has heavy recreational usage. To assess the microplastics in this environment, we employed the grab method to collect multiple ~500mL water samples along the watershed. These samples were vacuum filtered through glass microfiber filters and transferred to glass Petri dishes to dry in a laboratory oven at 60 degrees Celsius. Microplastics were counted using a grid under a 40x dissection microscope and categorized into four groups: fibers, films, fragments, and beads. The results showed the presence of microplastics in all samples from the Dry Creek watershed. On average, we found around 11 individual microplastics per sample. Around 64% of the microplastics were fibers, 10% were films, 22% were fragments, and 3% were beads. These findings confirm that Idaho’s waterways are not immune to the increasing problem of microplastic pollution. Further research is recommended for continued monitoring and in-depth investigation into the sources and potential impacts of microplastics. Understanding the pathways through which microplastics enter the watershed is essential for implementing effective pollution control measures in these types of environments.