Paleoclimatic implications of the relationship between oxygen isotope ratios of moss cellulose and source water in wetlands of Lake Superior

Our results show a consistent offset of 27 ± 1‰ between average swale water δ18O and cellulose δ18O values for hollow Sphagnum species, reflecting the fractionation associated with cellulose biosynthesis. When Sphagnum species from hummocks are included, the offset shows a larger variability (27 ± 3‰), pointing to evaporative effects affecting hummock species. This evaporative effect is more pronounced in emerged mosses, which show the largest difference (> 30‰) relative to their source water. The smaller variability associated with hollow species points to the possibility of performing species-specific analyses from peat cellulose for improved paleoclimatic reconstructions.