Using Lichen Biomarkers And Microparticles To Investigate Nonpoint Source Pollution in Two Seattle, Washington Neighborhoods

Lichen monitoring studies use physiological markers and metal accumulation to identify the degree of environmental contamination at a location. These are useful approaches for evaluating impact of a known stressor, but require a thorough understanding of the surveyed location to identify an unknown source. Comparing morphology and composition of airborne particles using a scanning electron microscope is a robust method for determining sources of contamination, but sampling equipment can be cost-prohibitive. This study will use lichen for collecting airborne particles to combine the strength of both methods and create a profile of metal accumulation, physiological endpoints, and particles associated with three point-sources of airborne metals in Seattle. These profiles will be compared to additional lichen from two nearby neighborhoods to estimate the contribution of each source to current air pollution. The profile will be composed of particle type and frequency, accumulation of about 30 metals, malondialdehyde production, chlorophyll degradation, and usnic acid content. In addition, an R script for automating the identification of particles on scanning electron microscope images of the lichen surface will be developed for this and future monitoring studies