Biogeochemical research in the Oceans and Cryosphere Centre studies the cycling of crucial elements in the oceans, such as carbon, nitrogen and iron, and their interactions with other substances and organisms as they move through Earth’s system.
Our work covers how chemical substances and biological organisms in the ocean are distributed, and how these are affected by natural processes and human activities. These include vertical mixing, transport, biological activity and exchanges between the atmosphere, geosphere, cryosphere and ocean, as well as the use of chemical tracers to quantify mixing processes.
Our ocean biogeochemical studies help us predict future environmental changes, by unravelling the complexities of marine systems and their significance in climate regulation and ecosystem sustainability. Our Biogeochemical research themes are described below.
The ocean sequesters a staggering amount of carbon dioxide from the atmosphere and is the primary natural control on Earth’s climate, driving us into and out of ice-ages throughout the geological past. The massive oceanic carbon reservoir is enabled by critical biogeochemical carbon sinks. The importance of these carbon sinks is so large, that even small changes in their efficiency could have massive implications for the climate and life on Earth.
Through a combination of state-of-the-art biogeochemical models, prolific autonomous data collection, and targeted laboratory and shipboard experimentation, we are working to understand the marine carbon cycle. Our focus is on how the marine carbon cycle – and its ability to keep carbon out of the atmosphere – will respond to massive inadvertent (human-caused emissions) and potentially intentional (carbon dioxide removal technologies) disturbances across an uncertain future.
The impact of this work will help to quantify the stakes of climate inaction, and determine if emissions reductions can be paired with thoughtful marine carbon dioxide removal technologies to help abate the worst impacts of climate change.
Trace elements and their isotopes play important roles in the ocean as nutrients, as tracers of processes now and in the past, and as contaminants.
Their biogeochemical cycling has direct implications for research in such diverse areas as the carbon cycle, climate change, ocean ecosystems and environmental contamination.
In the Oceans and Cryosphere Centre, our teams investigate the biogeochemistry of trace elements in the Southern Ocean, with projects addressing key research questions related to ocean productivity, carbon sequestration, ocean iron fertilisation, trace element speciation and cycling, and the supply of trace elements to the ocean (including atmospheric deposition).
We do this through a combination of shipboard and land-based sampling field programs, laboratory experiments, autonomous platforms and biogeochemical modelling.
We aim to understand the physical, chemical and biological processes involved in trace element cycles in the ocean sufficiently well that the response of these cycles to global change can be predicted, and their impact on the carbon cycle and climate understood.
The photosynthetic activity of single-celled microbes in the ocean fuels diverse marine food webs and drives the removal of carbon from surface waters and its ultimate transfer to the deep sea. This ocean productivity plays a key role in determining marine biodiversity and carbon cycling, and has a profound impact on the large-scale distribution of elements in the ocean, including nutrients, oxygen and trace metals. Ocean productivity depends on the interplay of the supply of nutrients and light, which in turn depend on ocean physics and geography.
We investigate large-scale patterns of ocean productivity and their drivers across a range of scales, from seasonal and multi-decadal to glacial-interglacial scales, with a strong focus on the Southern Ocean. We use biogeochemical floats, satellite observations, ship-board observations, sediment core reconstructions and biogeochemical models to quantify ocean productivity and predict how it might change in response to climate change and other drivers.
Image: Deployment of a biogeochemical Argo float from RV Investigator in December 2020. The float measures temperature, salinity, depth, oxygen, nutrients, pH, chlorophyll, light and particles from 2000 m to the surface every 10 days. Credit: Jakob Weis