Enhanced Dissolved Organic Matter Recovery from Saltwater Samples with Electrodialysis

Complexities associated with dissolved organic matter (DOM) isolation from seawater have hampered compositional characterization of this key component of global carbon and nutrient cycles. DOM isolation efficiency by electrodialysis (ED) from saltcontaining waters was optimized and evaluated on samples including coastal ocean seawater, open ocean seawater, artificial seawater from axenic cultures of marine phytoplankton, and artificial seawater samples containing standard compounds of different molecular sizes and charge. ED was performed with a system optimized for processing 2–10 L sample volumes. Additionally, the combination of ED and solid-phase extraction, using Bond Elut PPL exchange resin, was evaluated. Using only ED, the following DOC recoveries were achieved: coastal seawater, 71.3 ± 6.5 %; open ocean, 50.5 ± 3.1 %; phytoplankton cultures, 70.3 ± 12.5 %; glucose, 90.2 ± 2.1 %; EDTA, 67.5 ± 9.9 %; and vitamin B12, 98.3 ± 1.6 %. With the combination of PPL and ED techniques, an average DOC recovery of 76.7 ± 2.6 % was obtained for coastal seawater, but this recovery was not statistically different from seawater recoveries using only ED. Comparison of C/N ratios and fluorescence excitation emission matrices taken at the beginning and end of the recovery process for coastal samples processed using only ED indicated that the final recovered material was representative of the DOM present in the original samples. Electronic supplementary material The online version of this article (doi:10.1007/s10498-016-9306-2) contains supplementary material, which is available to authorized users. & Ellery D. Ingall [email protected] 1 Department of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA 2 Marine Science Program and Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC, USA 3 Department of Earth and Environmental Sciences and the Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA 4 Skidaway Institute of Oceanography, University of Georgia, 10 Ocean Science Circle, Savannah, GA 31411, USA 123 Aquat Geochem DOI 10.1007/s10498-016-9306-2