Temporal and spatial variation of atmospherically deposited organic contaminants at high elevation in yosemite national park, California, USA

Atmospherically deposited organic contaminants, such as pesticides and polycyclic aromatic hydrocarbons (PAHs), exhibit significant spatial and temporal variation at high elevations in Yosemite National Park. Research indicates that pesticide concentrations are generally lower in Yosemite compared to Sequoia-Kings Canyon National Parks, likely due to shorter air flow paths over agricultural lands and reduced local pesticide use. Conversely, PAH levels in sediment are higher in Yosemite, suggesting varying sources or transport mechanisms. The study sampled shallow-water sediment and tadpoles (Pseudacris sierra) across four high-elevation sites during the summers of 2006–2008, revealing that DDT-related compounds occasionally exceeded safety thresholds in both parks. While total cholinesterase activity in tadpoles did not show a consistent pattern, variability in chemical concentrations among sites and sampling periods contributed significantly to overall variation, with differences observed between sediment and tadpole data.

Bradford, D. F., Stanley, K. A., Tallent, N. G., Sparling, D. W., Nash, M. S., Knapp, R. A., McConnell, L. L., & Massey Simonich, S. L. (2012). Temporal and spatial variation of atmospherically deposited organic contaminants at high elevation in yosemite national park, California, USA. Environmental Toxicology and Chemistry, 32(3), 517–525. https://doi.org/10.1002/etc.2094