AQUATIC FULVIC-ACIDS IN ALGAL-RICH ANTARCTIC PONDS

We isolated fulvic acids from two antarctic coastal ponds by means of preparative scale column chromatography with XAD-8 resin. Both ponds are on Ross Island. Pony Lake at Cape Royds has abundant phytoplankton populations, and Feather Pond at Cape Bird has a luxuriant benthic algal mat. Neither site has higher plants in the watershed. The dissolved organic carbon (DOC) concentration in Pony Lake was very high, but the percentage of DOC accounted for by fulvic acid was low, as has been observed for other lakes with algal-derived DOC sources. Fulvic acid from Pony Lake was more enriched in nitrogen than fulvic acid from Feather Pond, with a C:N atomic ratio of 13 in Pony Lake and a C:N ratio of 24 in Feather Pond. The [C-13]NMR spectra for the coastal pond samples showed that the content of sp(2)-hybridized carbon atoms (aromatic or olefinic) was only 16.5% of the total spectral area for Pony Lake and only 20.1% for Feather Pond.