Seasonal Evolution of Terrigenous Dissolved Organic Matter in the South Atlantic Bight off Georgia in 2014

Six surveys of the central South Atlantic Bight (SAB) off of Georgia were conducted in 2014. The primary objective of the research cruises was to characterize estuary-shelf exchange and the dispersal of freshwater into the coastal ocean around Sapelo Island off the Georgia coast. The surveys, in April, May, July, August, September, and November, were intended to sample shelf conditions under different seasons. Most of the sampling stations were located at the mouth of the estu-aries around Sapelo Island and over the inner and mid-shelf (<60 km offshore). Eighty samples from transects extending across the shelf from the mouths of the Altamaha River and of Sapelo Sound were selected for the analyses of molecular composition using ultrahigh resolution mass spectrometry (Fourier transform ion cyclotron reso-nance mass spectrometry [FT-ICR MS]) and stable carbon iso-topic signatures (delta 13C). This data set includes spectral analysis of the DOM, including spectral slope (275-295nm wavelength), terrigenous peaks from mass spectrometry analysis, and a computed terrigenous index indicating fraction of terrigenous DOM in water samples.