AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
On-line Measurements of Particle Bound Reactive Oxygen Species in Ambient and Combustion Aerosols
STEPHEN FULLER, Jenny Nutter, Stephen Platt, Lisa Pfaffenberger, Peter Barmet, Josef Dommen, Urs Baltensperger, Andre Prévôt, Markus Kalberer, University of Cambridge
Abstract Number: 36 Working Group: Health Related Aerosols
Abstract Adverse health effects associated with aerosol particles in ambient air are well documented by epidemiological studies. However, due to the large variability in ambient particulate matter it is unknown what physical or chemical properties are responsible for these negative health effects. Previous studies have highlighted reactive oxygen species (ROS) in components of organic particulate matter, as being potentially a major cause.
An online measurement system was developed in the study presented here that collects water-soluble aerosol components and determines the ROS concentration by reaction with the fluorescent probe 2-7 dichlorofluorescein (DCFH). Particles were collected and continuously extracted on a wetted hydrophilic filter. The particles are collected and extracted in a solution of horseradish peroxidase (HRP) that allows immediate reaction of ROS on collection. The concentration of ROS is determined following subsequent reaction of the oxidised HRP with DCFH yielding a fluorescent reaction product, which is quantified in the continuous flow set-up using fluorescence spectroscopy. The detection limit of the system is approximately 10 nMoles of hydrogen peroxides per cubic meter of air.
This system was used to measure particle bound ROS concentrations during the ageing of primary moped combustion emissions in the presence of UV light and NOx in smog chamber experiments. The reactivity seen during the ageing experiments was found to be purely due to secondary organic aerosol with ROS concentrations of about 1nMole per microgram of SOA. The ROS concentration in these primary emissions are comparable with pure SOA systems from biogenic and anthropogenic precursors.