Donna Glinski

Honors in Chemistry

Major: Chemistry

Supervisor: Joan Willey, Chemistry and Biochemistry

Seasonal and Decadal Variations of Rainwater Formic and Acetic Acid in Wilmington, NC

Rainwater was collected on an event basis on the UNCW campus from January 2008 through March 2009 for analysis of formic and acetic acid. This is important because organic acids contribute to dissolved organic carbon (DOC) and free acidity (H+), and concentrations of both have decreased over the previous two decades at this location. A stability study of untreated, chloroformed, and frozen rain samples showed that preservation of samples needs to be done if analyses cannot be completed within 7 days. Another stability experiment of chloroform versus frozen samples also showed that the addition of chloroform proved superior to freezing samples. The formate to acetate ratio has increased back to where it was previously 20 years ago. The acetate concentration is the lowest it has been in 20 years based on three studies at this location. The growing season had concentrations twice as high as the non-growing seasons for both formic and acetic acid concentrations. The growing terrestrial storms had higher concentrations of formate and acetate than the growing marine storms, where non-growing seemed the same for both. This probably results from increased input from biogenic terrestrial sources during the growing season. This research was done to better understand the impacts of air quality regulation.