Exploring the vertical distribution of redox-sensitive elements in a coastal anoxic basin, Whycocomagh Bay, NS

Abstract

Oceanic dissolved oxygen has been decreasing in concentration due to climate change, and this is expressed most strongly coastal waters. Whycocomagh Bay (Bras d’Or Lake, Cape Breton, Nova Scotia) has a deep basin that has been reported to be anoxic below 20m depth (to the seabed at 48m) for at least half a century. It provides an accessible site where anoxic biogeochemical processes can be studied repeatedly. Water sampling was achieved using a prototype syringe sampler, and vertical profiles of several redox-sensitive elements are presented and analyzed, some which have not been measured previously in the Bras d’Or Lake. These profiles are focused in the anoxic basin, but other sites within and outside of Whycocomagh Bay are included for reference. These profiles reveal chemical gradients that inform hypotheses about causal processes and effects of anoxia and hypoxia, which may be tested with the continued use of the techniques developed here.