Microplastic Prevalence in 4 Oregon Rivers Along a Rural to Urban Gradient Applying a Cost-Effective Validation Technique

Abstract

Microplastics are ubiquitous in our environment and are found in rivers, streams, oceans, and even tap water. Riverine microplastics are relatively understudied compared with those in marine ecosystems. In Oregon (USA), we sampled 8 sites along 4 freshwater rivers spanning rural to urban areas to quantify microplastics. Plankton tow samples from sites along the Columbia, Willamette, Deschutes, and Rogue Rivers were analyzed using traditional light microscopy for initial microplastic counts. Application of Nile Red dye to validate microplastics improved microplastic identification, particularly for particles (Wilcox test; p = 0.001). Nile Red–corrected microfiber abundance was correlated with human population within 5 km of the sample site (R² = 0.554), although no such relationship was observed between microparticles and population (R² = 0.183). We found that plastics were present in all samples from all sites, despite the range from undeveloped, remote stretches of river in rural areas to metropolitan sites within Portland (OR, USA), demonstrating the pervasive presence of plastic pollution in freshwater ecosystems. Environ Toxicol Chem 2020;39:1590–1598. © 2020 SETAC

Observing Microplastics in the Environment through Citizen-Science-Inspired Laboratory Investigations

“…Fragmentation or degradation of larger plastic pieces by UV radiation, hydrolysis, and microorganisms can form smaller particles called secondary microplastics. − These particles are categorized as uneven fragments, pellets, rounded granules, or filaments, called microfibers . They are found on shorelines, lakes, and rivers. , Microfibers typically arise from fibers fragmented from washing synthetic clothing items. ,, A load of laundry (especially polyester and acrylic fabrics) can send several hundred to thousands of microplastics to wastewater treatment plants and eventually enter aquatic ecosystems. − Biodegradation of common textile materials is higher in lake water and activated sludge than in seawater, posing additional concerns for marine environments . Polyester fabrics pose a substantial threat to marine inhabitants as they are released at higher rates during laundering and fail to degrade in aquatic environments …”

What have we known so far for fluorescence staining and quantification of microplastics: A tutorial review

“…In field studies, different methods and equipment are applied to collect samples in specific environmental matrixes, including water, sand, sediment, the atmosphere, and biota (Table 1) (Dowarah et al, 2020;Scircle et al, 2020;Valine et al, 2020). For water samples, manta nets or trawls are commonly used to collect large-sized MPs (>100 μm) in surface waters, whereas pumping with filters (100 or 300 μm) is used as a complemental sampling method for smaller sized MPs ( < 100 μm).…”

Development and application of tests for microplastic detection in soil

“…Second, evidence suggests that microbeads from cosmetics and detergents are not to blame for the largest amount of microplastics emitted to seas (Duis and Coors, 2016). Instead, evidence suggests that plastic microfibres of diverse compositions and sources (Table 1.1 and 1.2) rank first in frequency among microplastics in the environment (air (Dris et al, 2016), soil (Wang et al, 2020a), sea (Reineccius et al, 2020), freshwater (Valine et al, 2020), fauna (Carlin et al, 2020), and overall (Xu et al, 2020)). Although not unique, the largest source of plastic microfibers in the environment is wastewater treatment and sludge disposal (see section 1.3, and Chapter 4).…”