Redox chemistry of West Antarctic Peninsula margin surface sediments

- Trace metal and productivity proxy concentrations were measured in surface sediments from 35 sites.
- Sediments appear to be suboxic due to seasonally high delivery of organic carbon.
- Cold waters may help to maintain redox conditions and promote trace metal accumulation.

Continental margin sediments are commonly studied using trace metal enrichments as proxies for characterizing their modern redox conditions and tracking past changes in bottom water ventilation and marine primary productivity. Currently little is known about the sedimentary redox history of the continental shelf west of the Antarctic Peninsula. Yet, environmental conditions in the Antarctic Peninsula region have changed rapidly in recent decades in response to global warming. Paleoclimate archives including bulk sediment trace metal enrichments can provide insight into both past and future environmental changes in this climatically sensitive region, and characterization of redox conditions in surface (modern) sediments is essential for establishing a framework for paleoredox interpretations. In this study we measured concentrations of trace metals (Ag, Cd, Re, and Mo) and productivity proxies (total Ba, organic carbon, and biogenic silica) in surface sediments from the Marguerite Bay, Gerlache Strait, and Bransfield Strait areas. Proxy concentrations suggest that sediments are generally suboxic due to seasonally high export of organic carbon from surface waters. Comparison of West Antarctic Peninsula trace metal/Al ratios to trace metal data from continental margins outside the Antarctic region demonstrates that although the West Antarctic Peninsula water column differs from other locations (e.g., it lacks a strong oxygen minimum zone), sedimentary redox chemistry is similarly controlled by organic matter decomposition, through slow recycling of highly seasonal export production falling through a cold water column.