UC Santa Cruz

The Lake Tahoe Basin struggles with litter issues including plastic pollution. Microplastics were first documented in the Tahoe Basin in 2019 and since then have been documented in several environmental compartments in the area. One environmental compartment that is not well understood is Lake Tahoe's lakebed sediments. This thesis examines sediment samples collected from 5 transect sites along Lake Tahoe’s east shore to better understand the distribution and chemical composition of microplastic particles in Lake Tahoe's sediments. Using density separation, digestion with hydrogen peroxide and chemical analysis using Raman spectroscopy and microscopy quantification using Nile Red dye, I found that across all sampling sites, the mean blank-corrected abundance was 2.70 ± 1.69 particles g⁻¹ dry sediment (mean ± SD). Particle (63 µm to 5 mm) abundances ranged from 1.01 to 4.96 particles g⁻¹ dry sediment across the five sampling sites. The highest abundance was observed at East Incline (ES6 4.96 particles g⁻¹), followed by Zephyr Cove (3.73 particles g⁻¹) and South Sand Harbor (2.65 particles g⁻¹). Lower abundances were observed at Hidden Beach (1.17 particles g⁻¹) and Nevada Beach (1.01 particles g⁻¹).