PROVIDENCE, R.I. [Brown University] Rhode Island's geography is famously small, but new measurements of the nitrogen cycle in its waterways suggest that even over a small distance, differences can be huge. Scientists report that the nitrogen-converting process anammox is almost completely absent in Narragansett Bay, even though it is going strong in Rhode Island Sound only 15 miles off the coast.
The novel and somewhat surprising finding, documented in the journal Limnology and Oceanography, raises intriguing questions about why the bay seems inhospitable to an important environmental process, said corresponding author Jeremy Rich, assistant professor of ecology and evolutionary biology at Brown University.
"Past research suggested anammox might be increasing in importance in the bay, but there was not any data to back it up. What we're showing is it's barely even there," Rich said. "What's wrong with the nitrogen cycle in lower Naragansett Bay? Why don't we have anammox? Have we disturbed it to the point where we are missing this process?"
Anammox anaerobic ammonium oxidation was only recently discovered and remains incompletely understood. It is one of two ways that nitrogen in various forms in seafloor sediments is converted back into its inert form (N2) that composes 80 percent of the atmosphere. The other process is denitrification. This conversion is not only a key step in the Earth's vital nitrogen cycle, but also it contributes to the health of waterways by removing excess nitrogen that can fertilize harmful algae blooms.
For their study, researchers including lead author Lindsay Brin sailed to the sites on the fishing vessel Virginia Marise every season over two years. They took measurements and collected sediment cores from the Providence River Estuary, Naragansett Bay (into which the estuary feeds), Rhode Island Sound (into which the bay opens), and the neighboring Block Island Sound.
|Contact: David Orenstein|