PLACERVILLE, Ca. (InEDC) CARI SPENCER, LA Times July 14, 2023
Sparkling Lake Tahoe may appear pristine, but its blue surface waters contain microplastic concentrations higher than those observed in ocean gyres — systems of ocean currents notorious for accumulating plastic waste — according to new research.
The study, published Wednesday in the scientific journal Nature, revealed that of the 38 lakes and reservoirs sampled across 23 countries, Lake Tahoe contained the third-highest concentration of microplastics.
Researchers first reported microplastics in Lake Tahoe in 2019 — a disappointing discovery about the lake, which straddles California and Nevada. Decades of conservation efforts and legal protections have worked to preserve the lake and its 72 miles of shoreline.
The team behind the new study, led by Veronica Nava, a postdoctoral scholar from the University of Milano-Bicocca in Italy, recorded plastics concentrations more than three times higher than those sampled using a similar method in the North Atlantic subtropical gyre.
The study filtered for microplastics larger than 250 microns, or the width of about three strands of hair.
It joins a growing body of research sounding the alarm on the prevalence of microplastics. The tiny plastic particles, less than the size of a sesame seed, have been found all over — in the ocean, in Arctic snow, in the air we breathe, the food we eat and in our blood. There’s seemingly no escape.
Sudeep Chandra, the director of the Global Water Center at the University of Nevada, Reno, and co-author of the study, said the research highlights just how pervasive microplastics have been in freshwater ecosystems. Every lake sampled — even the most remote lakes — contained microplastics. That included Castle Lake near Mt. Shasta in Northern California.
“We often think about plastics being developed in watersheds and then moving into the ocean and collecting in the ocean,” Chandra said. “But what this study shows you is that fresh waters, including lakes and reservoirs, are important conduits of plastic.”
The team behind the study placed surface nets on lakes around the world, a practice commonly used for collecting data on marine microplastics, sampling lakes with a range of depths, population densities and watershed sizes…
