THE INFLUENCE OF HYDROLOGY ON DISSOLVED ORGANIC MATTER COMPOSITION AND DEGRADATION IN THE ALTAMAHA RIVER AND ESTUARY (E)
Estuaries are hot spots of dissolved organic matter (DOM) cycling, where DOM composition is controlled by the relative contribution of different sources and by complex interactions of physical, chemical, and biological processes. Even though the transfer of organic matter from land to sea is one of the most important pathways for preservation of terrigenous production, the amount and composition of the DOM linking terrestrial to ocean carbon cycles through rivers and estuaries is uncertain. Changes in river discharge and freshwater input may impact DOM distribution, composition, and cycling in estuaries. The Altamaha River in Georgia, USA, is the third largest freshwater input to the Atlantic Ocean in North America. The hydrology of this river is known to vary seasonally, with the highest discharge levels historically occurring in late March to early April. Surface riverine and estuarine samples were collected monthly for one year, beginning in October 2015. Samples were dark incubated over short- and long-term intervals. Ongoing analyses include: chromophoric dissolved organic matter (CDOM), dissolved organic carbon (DOC), and ultrahigh resolution mass spectrometry (FT-ICRMS). Preliminary results show that an increase in river discharge resulted in higher DOC concentration, increased DOM aromaticity and average molecular size, and unexpected higher biodegradation rates. As discharge increases, the residence time of terrestrial DOM in the estuary decreases, resulting in implications for the export of this material to the Atlantic Ocean.
Letourneau, M. L., University of Georgia, USA, firstname.lastname@example.org
Medeiros, P. M., University of Georgia, USA, email@example.com
Time: 11:00 - 12:00
Location: Poster/Exhibit Hall
Presentation is given by student: Yes