A Survey of California Plant Species With a Portable VOC Analyzer for Biogenic Emission Inventory Development

An accurate estimate of the magnitude of biogenic volatile organic compound (BVOC) emissions relative to anthropogenic VOC emissions in California's airsheds is critical for formulating effective strategies to reduce concentrations of fine particles, ozone, and other secondary air pollutants which affect human health and reduce yields of agricultural crops. However, California's natural landscapes contain more than 5800 listed species, and urban landscapes contain hundreds more. A taxonomic method has been proposed to assign BVOC emission rate measurements to unmeasured species, but data were needed for additional plant families and genera to further develop the taxonomic approach. Replicate samples of live foliage of more than 250 plant species were placed in plastic bags, in both light and darkened conditions, and the BVOC emissions measured with a calibrated portable analyzer unit (PAU), and categorized as low, medium or high. To validate the PAU approach we compared our PAU-measured BVOC emissions for approximately 60 plant species with published values based on gas chromatography (GC) and GC-mass spectrometry and found them to be well correlated. For approximately 200 plant species not previously measured, the PAU data indicated that plant taxonomy served as a useful method for characterizing the magnitude and nature of emissions (either light or dark, or both). The method employed was more suited for detecting isoprene emissions, due to their relatively higher magnitudes, than emissions of monoterpenes or oxygenated compounds. The results provide further evidence that plant taxonomy can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera.