Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Field collected DOC from estuarine waters near Sapelo Island, GA in 2012 and 2013 was analyzed for chemical composition. Analysis of the dissolved organic matter pool retrieved by solid phase extraction (PPL resin) was analyzed to determine delta-13C ratios and carbon concentration.

DOM was collected in Doboy Sound off the southeastern U.S. in November 2012, May 2013 and September 2013. At least 3 replicates were collected for each sample. Immediately after collection, samples were filtered (using 0.7 μm Whatman GF/F filters pre-combusted at 450°C for 5 h and pre-washed 0.2 μm 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).

DOC concentrations from water samples and extracts (i.e., dried and resuspended in ultrapure water) were measured with a Shimadzu TOC-VCPH analyzer. SPE efficiency across all samples was 75±7% of the DOC.

Bulk delta-13C ratios of extracted DOC (SPE-DOC) were measured with a Finnigan MAT 251 isotope ratio mass spectrometer after complete drying. Precision and accuracy was better than 1 ppt, and procedural blanks did not yield detectable amounts of carbon isotopes. The molecular composition of the DOM extracts (15 mg C L-1 in 1:1 methanol/water) was analyzed using a 15T Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS; Bruker Daltonics) with electrospray ionization (negative mode) as in Seidel et al. (2014).

References:

Dittmar, T., Boris Koch, Norbert Hertkorn, and Gerhard Kattner. 2008. A simple and efficient method for the solid-phase extraction of dissolved organic matter (SPE-DOM) from seawaterLimnol. Oceanogr.: Methods 6, 2008, 230-235

Medeiros, P. M., M. Seidel, T. Dittmar, W. B. Whitman, and M. A. Moran (2015), Drought-induced variability in dissolved organic matter composition in a marshdominated estuary, Geophys. Res. Lett., 42, 6446–6453, doi:10.1002/ 2015GL064653.

Seidel, M., Melanie Beck, Thomas Riedel, Hannelore Waska, I G.N.A. Suryaputra, d, Bernhard Schnetger, Jutta Niggemann, Meinhard Simonc, Thorsten Dittmar. 2014. Biogeochemistry of dissolved organic matter in an anoxic intertidal creek bank. Geochimica et Cosmochimica Acta 140:418-434. http://dx.doi.org/10.1016/j.gca.2014.05.038

BCO-DMO Processing:
- added conventional header with dataset name, PI name, version date
- column names reformatted to comply with BCO-DMO standards
- replaced spaces with underscores

Description from NSF award abstract:
Long-standing questions regarding the fate of dissolved organic carbon (DOC) in coastal oceans require a better understanding of the network that links bacterioplankton metabolism with carbon transformation. These questions address uncertainties about the composition of the bioreactive DOC components transformed in ocean margins, and the role of bacterial taxonomic and genetic composition in determining the fate of DOC.

This project will infuse a new type of data into coastal carbon cycle research based on high-resolution chemical analysis coupled with bacterial gene expression measures. It will extend DOC process studies down to the single-compound level and bacterial activity studies down to the single-gene level, and integrate this information into existing bioinformatic resources for biogeochemical and modeling applications.

The specific goals of this project are:
1) To reconstruct major components of the network linking DOC composition, DOC turnover, and bacterial heterotrophy in the coastal ocean (the composition of the DOC pool, the major bioreactive components, the bacterioplankton taxa mediating transformations, and the bacterial genes and pathways responsible).

2) To test hypothesized network links for selected DOC compounds using a simplified system that queries individual DOC compounds against a complex natural microbial community.

3) To test hypothesized network links for marine bacteria using a simplified system that queries a single generalist heterotrophic bacteria against a complex natural DOC pool.

4) To verify predicted DOC-gene linkages that are most informative about heterotrophic activities of bacterioplankton.

This research addresses fundamental questions on bacterial mediation of organic carbon fate in the ocean and atmosphere. As such, these investigations linking the chemical changes in dissolved organic carbon with patterns of gene expression in coastal bacterioplankton communities will be of interest to scientists across several disciplines.

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Note: The project acronym, SIMCO, means "Sapelo Island Microbial Carbon Observatory".