Radiocarbon Geochemistry of Modern and Ancient Arctic Lake Systems, Baffin Island, Canada

Abstract

Abstract The accuracy of Arctic lake chronologies has been assessed by measuring the 14 C activities of modern carbon sources and applying these isotopic mass balances to dating fossil lake materials. Small (<1 km 2 ) shallow (<25 m) Arctic lakes with watersheds <12 km 2 have soil and peat stratigraphic sections with 14 C activities ranging from 98 to 51% Modern. The 14 C activity of particulate organic carbon, dissolved organic carbon, and dissolved inorganic carbon from lake and stream waters ranges from 121 to 95% Modern. The sediment–water interface of the studied lakes shows consistent 14 C ages of ∼1000 14 C yr, although the 14 C activity of living aquatic vegetation is 115% Modern. Radiocarbon measurements of components of the lacustrine carbon pool imply that the ∼1000 14 C yr age of the sediment–water interface results from deposition of 14 C-depleted organic matter derived from the watershed.