ONGOING RESEARCH PROJECTS

Nutrient cycling within high latitude environments during past climate transitions

The Arctic Ocean is currently one of the most rapidly warming regions of the world. Among the most striking effects of this warming is a drastic reduction in sea ice, with some models predicting a seasonally ice free Arctic Ocean by 2050. These changes occurring within the Arctic Ocean will have complex effects on nutrient availability and, subsequently, primary productivity. However, different model scenarios for the biogeochemical response to anthropogenic climate change within the Arctic Ocean predict either elevated or reduced nutrient supplies, illustrating the need for improved constraints on how nutrient delivery and benthic remineralization will evolve under warmer conditions. The sedimentary record provides an opportunity to reconstruct biogeochemical cycles during past intervals of sea ice minima to help predict what may occur in the future. Using sediment cores from north of Svalbard, the group is reconstructing past changes in micro- (Fe) and macro- (phosphorus (P), nitrogen, and silica) nutrient delivery and recycling in response to climatic and oceanographic perturbations. 

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This work is done through international collaborations with the Arctic in Rapid Transition early career network and the Norwegian Nansen Legacy Program.

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Modern benthic biogeochemistry
 

Sediments deposited at the bottom of lakes and oceans can act as sources or sinks of carbon, nutrients, and trace metals. Biogeochemical and early diagenetic processes control the release of these elements from the seafloor. By pairing sediment and porewater geochemistry, we can improve our understanding of nutrient recycling from the sediments to the overlying water column, as well as how environmental signals are preserved within the sedimentary record.

Current projects include work focused on the Barents Sea and on the Eurasian Arctic margin. This work includes collaborations with the UK National Environmental Research Council (NERC)-funded Changing Arctic Ocean Seafloor (ChAOS) project and the Norwegian Nansen Legacy project.

Mechanisms of enhanced organic carbon burial during the Late Cretaceous
The Late Cretaceous was characterized by elevated pCO2 and an equable, warm climate, making it among the best examples of a greenhouse climate within the last 100 Ma of geologic history. During this time, a vast epicontinental seaway flooded the western interior of North America that extended from the Gulf Coast to the Arctic Ocean. The resulting sedimentary record of the Western Interior Seaway (WIS) includes episodic deposition of organic carbon-rich black shales, including during a series of Oceanic Anoxic Events (OAEs). Multiple processes control marine black shale deposition during OAEs, including changes in primary productivity, organic matter preservation, and sedimentary dilution. Much of our recent work has centered on sediments deposited within the WIS during a prolonged organic carbon burial event that has been identified as the Coniacian-Santonian OAE 3 (~88−84 Ma) to evaluate the relative roles of these forcing factors on marine carbon burial. This work will be expanding in the future through the IODP Expedition 392 to the Agulhas Plateau. More details are available here.