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Paper No. 69-35
Presentation Time: 9:00 AM-5:30 PM
BIOMONITORING IN SEATTLE: SPATIAL VARIATION OF AIRBORNE PM CONCENTRATIONS IN INDUSTRIAL AND HIGH-TRAFFIC AREAS
Although transportation is a large source of air particulate pollution in the U.S., air quality is currently not routinely monitored on the street level or using methods that could determine particulate composition. Biomonitoring- using biological organisms (in this case tree leaves) as sample collectors- provides a simple and inexpensive alternative air quality monitoring apparatus that is at the human spatial level, can collect micron-sized particles, and can be found in closely-spaced locations, so that there is a dense area collection network. Magnetic methods such as SIRM and magnetic susceptibility have been used to gauge PM concentrations on the street level (Hoffman et al 2014, Kardel et al 2011, Lehndorff & Schwark 2004, Maher et al 2008) using biomonitors such as tree leaves. Total PM concentrations correlate well with measured magnetic values on leaf surfaces because PM contains magnetic particles from iron impurities released from fossil fuel vehicle exhaust, and other vehicle sources such as brakes (Sagnotti et al 2009). According to a study that compared the biomagnetic and air quality monitor PM10 concentrations in urban, sub-urban, and industrial areas, the biomagnetic PM10 results indicate that the concentrations were lowest in sub-urban emissions, while the air quality monitors detected the lowest concentrations of PM10 in industrial areas (Hofman et al 2014). The geographic focus of this study is the Seattle area because it has the most traffic in the Pacific Northwest (Seattle Department of Transportation) and because a mix of residential and community activities are located near sites of industry include manufacturing, warehousing, commercial, container shipping and support activities, concentrated in the south Seattle Duwamish Valley (Abel et al 2015). This study uses rock-magnetic methods (SIRM, magnetic hysteresis) to characterize types of particulates, and map the spatial variation of Seattle’s air pollution. Susceptibility readings on ninety leaves collected from the Duwamish area have found pollution hotspots along MLK Jr. Way S (up to 148.7 X 10-8 SI).