02340nas a2200241   4500008004100000245013800041210006900179260001200248300001100260490000600271520148800277100002301765700002401788700002301812700001901835700002001854700002201874700001901896700001701915700001801932700002701950856012101977       2013                        eng d00aCharacterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica0 aCharacterization of fulvic acid fractions of dissolved organic m  c12/2013  a0450150 v83 aDissolved humic material (HDOM) is ubiquitous to all natural waters and its source material influences its chemical structure, reactivity, and bioavailability. While terrestrially derived HDOM reference materials distributed by the International Humic Substances Society (IHSS) have been readily available to engineering and scientific communities, a microbially derived reference HDOM was not, despite the well-characterized differences in the chemistry and reactivity of HDOM derived from terrestrial versus microbial sources. To address this gap, we collected a microbial reference fulvic acid from Pony Lake (PLFA) for distribution through the IHSS. Pony Lake is a saline coastal pond on Ross Island, Antarctica, where the landscape is devoid of terrestrial plants. Sample collection occurred over a 17-day period in the summer season at Pony Lake. During this time, the dissolved organic carbon (DOC) concentrations increased nearly two-fold, and the fulvic acid fraction (collected using the XAD-8 method) accounted for 14.6% of the DOC. During the re-concentration and desalting procedures we isolated two other chemically distinct fulvic acid fractions: (1) PLFA-2, which was high in carbohydrates and (2) PLFA-CER, which was high in nitrogen. The chemical characteristics (elemental analysis, optical characterization with UV–vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.1 aCawley, Kaelin, M.1 aMcKnight, Diane, M.1 aMiller, Penney, L.1 aCory, Rose, M.1 aFimmen, Ryan, L1 aGuerard, Jennifer1 aDieser, Markus1 aJaros, Chris1 aChin, Yu-Ping1 aForeman, Christine, M.  uhttps://mcm.lternet.edu/content/characterization-fulvic-acid-fractions-dissolved-organic-matter-during-ice-out-hyper