Deuterium content of humic acids from marine and non-marine environments

Deuterium values obtained for humic acids isolated from marine sediments from the NE Pacific are in the range of $\text{δ}\text{D}\text{= (?105 ± 5)‰}$, corresponding to values obtained for marine plankton from the same area. Soil humic acids have a much broader range of δD values (?57 to ?97‰), depending on the isotopic values of the precipitation and the isotopic composition of the parent plant precursor.Data obtained on hydrogen isotope distribution confirms previous hypotheses based on chemical analysis and on carbon isotopes, which indicated the authigenic nature of marine humates.