Data from: Microplastic prevalence in 4 Oregon rivers along a rural to urban gradient applying a cost‐effective validation technique

Microplastics are ubiquitous in our environment and are found in rivers,
streams, oceans, and even tap water. Riverine microplastics are relatively
understudied compared to those in marine ecosystems. In Oregon, we sampled
eight sites along four 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-value=0.001).  Nile Red-corrected microfiber abundance was
correlated with human population within five kilometers of the sample site
(R²=0.554), though no such relationship was observed between
microparticles and population (R²=0.183). This study finds plastics
present in all samples from all sites, despite the range from undeveloped,
remote stretches of river in rural areas to metropolitan sites within
Portland, demonstrating the pervasive presence of plastic pollution in
freshwater environments.