The structure of marine fulvic and humic acids

Fulvic and humic acids were isolated from near surface seawater samples obtained at five biologically diverse sites in the Gulf of Mexico in quantities sufficient for detailed NMR and chemical studies. A gas lift pump and a 1500-1 extraction facility provided halfgram quantities of material. The proton NMR spectra of all fulvic and humic acids studied were remarkably similar and differed mainly in the absence of aromaticity in the fulvics. These observations, coupled with published spectra and chemical data, suggest a class structure and general mechanism of formation for marine humic substances. The proposed structures are crosslinked, autoxidized, polyunsaturated fatty acids.