Highly polar organic compounds in atmospheric fine particles and cloud water: a study in the northeastern United States

Particulate matter is a ubiquitous component of Earth’s atmosphere, but the degree to which it influences cloud formation and climate is not well understood. Highly polar organic compounds, or HPOC, are thought to be important in cloud formation due to their ability to attract water molecules. This study’s goals included the quantification of HPOC in the atmosphere, study of correlations with sulfate and ozone to determine if the same production mechanisms are relevant, and study of temporal trends. Two sample sets were analyzed: a set of particulate matter filters from in and around the New York City area collected from 2002-2007, and a set of cloud water samples from upstate New York collected in the summer of 2010. A lab method for the use of PFBHA was developed to facilitate analysis of compounds with an oxygen atom double-bonded to a carbon atom. This method was used in conjunction with BSTFA derivatization, which aids analysis of acids and other compounds containing a hydrogen atom bonded to an oxygen atom. Samples were analyzed with gas chromatography/mass spectrometry. The results focus primarily on four HPOC: cis-pinonic acid, glyoxal, glyoxylic acid, and oxalic acid. These and other compounds were quantified in both sample sets. The concentrations of the compounds varied from season to season in the PM samples, but there was no clear seasonal cycle. Concentrations were typically highest at the urban sites. HPOC made up a larger portion of total organic carbon within the cloud water than in the PM, even though the amount of total organic carbon was higher in the PM. The correlation of HPOC with sulfate was considerably more pronounced in the cloud water samples, suggesting that, like sulfate, several of these compounds may be produced primarily within cloud droplets.Ph. D.Includes bibliographical referencesby Jessica Ann Sagon