Chemistry Weekly Seminar - Dr. Cora Young
Professor Cora Young, York University, Dept. of Chemistry, will present a seminar in THORV 124 at 1:30PM
Title:
Sources and implications of the atmospheric formation of strong acids: Perfluoroalkyl acids and hydrochloric acid
Abstract:
The atmospheric chemistry of many strong atmospheric acids (pKa < 1) remains an open question. The high surface activity of strong acids leads to short atmospheric lifetimes, measurement challenges, and implications for heterogeneous chemistry. In this presentation, I will focus on the atmospheric chemistry of persistent, toxic perfluoroalkyl acids (PFAAs) and the dominant component of reactive chlorine, hydrogen chloride (HCl).
Despite their strong acidity and short atmospheric lifetimes, PFAAs have been shown to undergo long-range transport. To explore the mechanisms driving this transport, my group collects and analyzes atmospheric deposition. Using deposition dating back to the 1960s from two Arctic ice cores, we observed that atmospheric formation from volatile precursors was the dominant source for most PFAAs. I will describe the mechanisms and sources for different PFAA compounds, including the influence of policy such as the Montreal Protocol.
Over the past ten years, the impacts of reactive chlorine (Cly = HCl + ClNO2 + HOCl + 2Cl2) on air quality have become apparent. The dominant component of Cly is HCl, which is extremely challenging to measure with high time resolution. My group used a compact cavity ring-down spectrophotometer to measure ambient HCl in the indoor and outdoor atmosphere at 0.5 Hz. Using these measurements, we can effectively determine sources of HCl to the atmosphere. Observations from marine and continental urban areas will be presented.