DOM was collected in Doboy Sound off the southeastern U.S. in July and October 2014. Six 20 L carboys were filled with water and wrapped in black plastic. Three were processed immediately, while the remaining three were returned to Doboy Sound for a 24 h dark incubation before processing by an identical protocol. This experimental scheme was carried out twice during each sampling event, once at high tide (HT) and once at low tide (LT). Immediately after collection, samples were filtered (using 0.7 \u03bcm Whatman GF/F filters pre-combusted at 450\u00b0C for 5 h and pre-washed 0.2 \u03bcm Pall Supor membrane filters), and aliquots were stored frozen for DOC analysis. Filtrates were acidified to pH 2, and DOM was isolated using solid phase extraction (SPE) cartridges (Agilent Bond Elut PPL) as in Dittmar et al. (2008).
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The molecular composition of the DOM extracts (200 mg C L-1 in methanol) was analyzed using a 9.4T Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) with electrospray ionization (ESI; negative mode) at the National ICR Users\u2019 Facility at the National High Magnetic Field Laboratory (NHMFL, Florida State University, Tallahassee, FL).
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Assignment of molecular formulae was performed by Kendrick mass defect analysis (Wu et al., 2004) with PetroOrg software (Corilo, 2015) considering a maximum mass error of 0.5 ppm and using the criteria described by Rossel et al. (Rossel et al., 2013).
Dissolved organic matter (DOM) from field and incubation collections of Doboy Sounds estuarine waters near Sapelo Island, GA in July and October 2014 was analyzed for chemical composition. Analysis of the dissolved organic matter pool retrieved by solid-phase extraction (PPL resin) was analyzed to determine chemical formulas (by Fourier transform ion cyclotron resonance mass spectrometry, FT-ICR MS).
BCO-DMO Processing:
\n- added conventional header with dataset name, PI name, version date
\n- column names reformatted to comply with BCO-DMO standards