Date/Time
Date(s) - 03/02/2022
1:30 pm - 2:30 pm

FromParticulate Matter to Precipitation: Reaction and Transport of Chemicals in theAtmosphere

Date: Thursday, February 3, 2022 

Time: 1:30-2:30 

Zoom – contact chemgrad@mcmaster.ca for details 

Host: Kay McCallum 

Abstract: Herewe will explore two stories of how chemicals move through the atmosphere. Thefirst concerns brown carbon, a collective term for light-absorbing organiccompounds that impact Earth’s climate by absorbing solar radiation. Onemechanism for brown carbon formation in the atmosphere occurs throughparticle-phase reactions of carbonyl compounds and amines. Our work seeks tocharacterize rates and products of multiphase reactions of hydratedmethylglyoxal films with gas-phase methylamine by using infrared spectroscopyand liquid chromatography-mass spectrometry. Understanding the formation andevolution of brown carbon aerosols can help us better model changes in globalradiative forcing. In the second story of chemicals moving through theatmosphere, we monitor the deposition of per- and polyfluoroalkyl substances(PFAS), which are long-lived contaminants of concern for human health. We havequantified the concentrations of 15 PFAS in rainwater from the central UnitedStates. Concentrations of perfluorooctanoic acid (PFOA) and perfluorosulfonicacid (PFOS) were comparable to levels observed over the past two decades, inspite of regulatory restrictions. We also detected HFPO-DA (Gen X), areplacement for legacy PFAS, at all measurement sites. Statistical analysishighlighted the importance of local point sources for PFAS deposition.