CUPRIC OXIDE OXIDATION-PRODUCTS OF NORTHERN PEAT AND PEAT-FORMING PLANTS

Alkaline cupric oxide oxidation and proximate analysis were used to in vestigate the sources and diagenetic state of organic matter in six Sp hagmum-dominated peatlands located between Alberta, Canada, and Ohio, U.S.A. Cupric oxide oxidation was also used to characterize vascular a nd nonvascular wetland plant species to provide a specific biological fingerprint of these plant tissues. Oxidation of 15 species of Sphagnu m moss released large quantities of unsubstituted p-hydroxyl phenolic compounds as well as the species specific sphagnum acid (p-hydroxy-bet a-[carboxymethyl]-cinnamic acid). By contrast, vascular plant tissues released large amounts of lignin oxidation products. Cupric oxide oxid ation of Sphagnum peat from more northerly sites produced mainly p-hyd roxyl phenolic monomers with lesser amounts of vascular lignin derived phenols. in contrast, southern sites and those dominated by woody veg etation produced oxidation products characteristic of vascular plant l ignin. A distinct relationship exists between the amount of acid-insol uble Klason lignin and both the diagenetically sensitive phenolic acid to aldehyde ratios as well as the total yield of vanillyl phenolic ox idation products. We found evidence of selective decay of phenolic lig nin precursors. These relationships indicate the lignin component in s urficial layers of Sphagnum-dominated peat is influenced by both Sphag num and vascular plant lignin, and the structure of lignin appears to undergo diagenetic changes in these layers. Application of an end-memb er mixing model revealed that lignin oxidation products poorly predict ed vegetational composition of the lignin in more decomposed peat, pro bably as a result of selective decay of lignin structural phenols.