AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
An Analysis of Trace Metals in Car Emissions
JOSEPH SALAZAR, Benton Cartledge, Allen Robinson, Yunliang Zhao, Rawad Saleh, Greg Drozd, Allen H. Goldstein, Brian Majestic, University of Denver
Abstract Number: 413 Working Group: Combustion
Abstract Motor vehicles are a major contributor to the release of combustion particulate matter (PM) in the atmosphere. In 2015, 9.16 million barrels of gas per day were burned by motor vehicles. Soluble and insoluble metals are contained in the PM resulting from breakdown of the vehicle steel, as well as from the combustion, the motor oil, and trace concentrations already present in the fuel. Soluble element fractions from PM contribute to the creation of reactive oxygen species, which create oxidative stress on the respiratory system. To better understand combustion products, PM was collected from vehicle tail pipes. The vehicles were driven on a dynamometer operated by the California Air Resources Board (CARB) primarily on the California Unified (UC) Drive Cycle. This drive cycle lasts for 1435 seconds and runs for approximately 15.7 km and simulates driving conditions in California including driving on and off the highway. The UC drive cycle has a maximum speed of 104.6 km/h and an average speed of 39.6 km/h, including several stops. PM from the exhaust was collected on acid-cleaned Teflon filters. To improve detection limits, we first developed a method to measure both water-soluble and total metals using the same filter. This method included soaking the filters in Milli-Q (>18.0 M ohm) water for two hours then filtered with nitro-cellulose filters. The remaining PM was digested via a strong acid microwave digestion and measured for trace elements using ICP-MS. Total and soluble elements were quantified the most significant being Fe with a range 0.0015-0.098 micro-grams/km and average of 0.013 micro-grams/km, Cu with a range 0.0004-0.047 micro-grams/km and average of 0.0070 micro-grams/km, and Zn with a range 0.0033-0.16 micro-grams/km and average of 0.039 micrograms/km. The results also showed a high fraction of average soluble Fe (28%), Cu (63%), and Zn (64%) from the filters.