What Rains Down on Us? Atmospheric Chemistry
A complex mixture of chemical compounds, rainwater includes organic acids, sugars and metal ions in trace amounts evasive to detection with older technology. However, even trace amounts of harmful chemicals can build up over time. Now, with the ultra-sensitivity and high resolution of the 600 MHz NMR spectrometer, members of UNCW’s Marine Atmospheric Chemistry Research Laboratory (MACRL) can pinpoint these materials and potentially determine their source.
“The technology will allow us to perform more sophisticated NMR experiments which give two- and three-dimensional images of the mixture of compounds in rains, enabling us to identify individual chemicals,” says professor of chemistry and biochemistry Pamela Seaton. For example, in the case of sugar molecules in rainwater, scientists will be able to determine whether the molecule is table sugar, a plant sugar, bacterial sugar or some other type.
Chemical changes are evident in NMR spectra. Scientists analyze the spectra of rainwater for patterns that might lead to a better understanding of atmospheric processes. They do experiments with rainwater that mimic atmospheric processes to understand chemical reactions; for example, how sunlight changes the components of rain. With the 600 MHz NMR these studies can be done more quickly — accomplishing in 16 hours what the older, lower-powered 400 MHz NMR took 60 hours to do.
In a broad sense, the unknown compounds identified by the new 600MHz NMR will help in understanding processes involved in the burning of fossil fuels. “The more we know about what’s in the atmosphere, the better equipped we will be to understand environmental problems, like what might be impacting global warming,” Seaton says.
MACRL researchers are experts in analytical chemistry, NMR spectrometry, sediment chemistry, marine organic chemistry, potential impacts of global warming and sea level rise, trace metal speciation in estuarine and atmospheric waters, photochemically mediated processes that impact environmental systems as well as the fate of pharmaceutical and personal care products in the marine environment. The team includes 11 graduate students and six-to-12 undergraduate research students per year. In addition to Seaton, core members are professors Joan Willey, Robert Kieber, Brooks Avery, Ralph Mead and Steve Skrabal.