Assessment of carboxyl groups of some Canadian Arctic fossil woods to evaluate their degradation

Five fossil woods from the Canadian Arctic, previously studied with standard methods of chemical analysis, were examined with respect to different forms of carboxyl groups (protonated, carboxylate and esters) and compared with those of the reference woods. The fossil wood from Resolute, Cornwallis Island, anatomically identified as white pine, and the sample GH28, tentatively identified as larch or redwood, exhibited only small differences with respect to the forms and amounts of carboxyls in the reference species. Fossil GH61, identified as Douglas fir, showed all the original forms, although in amounts slightly larger than the reference Douglas fir. The two unidentified fossils had undergone thorough degradation. In these last samples, as in several European fossil woods, the carboxyl groups seem to derive from oxidized structures of degraded lignin.