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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Biogeochemical cycles and their response to global environmental changes


Covering 70% of the planet’s surface, the Ocean plays a key role in all major elemental cycles in the Earth system. It acts as a major sink for atmospheric CO2, and holds the largest actively cycling reservoir of carbon. Many elemental cycles are intimately linked and interact through life processes – hence ‘biogeochemical cycles’ – and are sensitive to ongoing global environmental changes. The Marine Biogeochemistry Group has a track record of leading the pelagic component of the UK Ocean Acidification Research Programme (UKOARP), making major contribution to the NERC Shelf Sea Biogeochemistry Programme, and has shown significant impacts of increasing CO2 and ocean warming on oceanic biogeochemistry. We are further investigating the complex intricacies of interacting oceanic biogeochemical cycles, ranging from trace elements to macronutrients and carbon, and their responses to ongoing multifaceted global environmental changes.

Figure 1. Photo credit: Amber Annett
Figure 1. Photo credit: Amber Annett

Key Questions:

1. How is climate change altering the biogeochemistry of the Polar Oceans? – What is changing in the western Antarctic Peninsula? How is glacially-sourced iron from Greenland delivered to the Labrador Sea?

2. What are the key sources and sinks of trace elements? – What are the spatial and temporal ranges of influence from mid-ocean ridges?

3. How does resource limitation (e.g. availability of light and nutrients) restrict the activity of marine phytoplankton and the biogeochemical processes they influence? – How will they respond to ongoing changes and future scenarios?

4. What are the linkages between ocean biogeochemical processes and climate variability? – What are the biological, physical, and chemical processes that control the ocean's carbon cycle? And the cycling of greenhouse gases?

5. How is ocean biogeochemistry currently changing and has been through Earth history? - How has Earth stayed habitable for 3 billion years? What are the controls on biogenic element distributions in the Ocean?

Figure 2. Photo credit: Amber Annett
Figure 2. Photo credit: Amber Annett

How do we do it?

We use radium and oxygen isotopes to quantify nutrient and essential trace element inputs from melting glaciers; and to understand the magnitude and time scale of iron transport from Greenland fjords across the shelf to the open ocean. We further investigate the release of iron and nutrients from marine sediments in glacial fjords and across the shelf.

Understanding the biogeochemical cycling of trace elements requires knowledge of their diverse sources and sinks, as well as their transport and chemical form in the ocean. Using large ocean basin sections – and linked to the international GEOTRACES study – we determine the sources and sinks of trace elements (concentration, chemical speciation and chemical form) to characterise the physical, chemical and biological processes regulating their distributions

We further use novel trace metal isotopes to identify the sources of trace elements. Combining physical measurements with concentration and isotope data, we identify how mixing impacts upon the cycling of these trace elements.

We combine in situ observations, at sea experimentation, analyses of time-series data and large global datasets, utilisation of our dissolved nutrients and carbonate chemistry facilities, as well as Environmental Sequencing Facility, coupled with numerical models to develop mechanistic understanding of the interactions of microbes with their environment. We further use this mechanistic understanding to predict how system activity and interacting biogeochemical cycles will alter under a range of different scenarios.

Figure 3. Photo credit: Amber Annett
Figure 3. Photo credit: Amber Annett
Figure 4. Photo credit: Amber Annett
Figure 4. Photo credit: Amber Annett









  1. Figure 1. RRS James Clark Ross heading south through sea ice, off the coast of Adelaide Island, Antarctica.
  2. Figure 2. Hosing down sampling equipment and sieving sediment cores aboard the RRS James Clark Ross in Ryder Bay, Antarctica - as part of the projects RaCETraX and ICEBERGS to understand the impacts of rapid glacial retreat on benthic ecosystems and biogeochemistry.
  3. Figure 3. Two Chinstrap penguins observed scientists and crew from the RRS James Clark Ross, as they sampled surface waters in Börgen Bay, Anvers Island, Antarctica. Small boats are used to carefully and safely collect uncontaminated seawater for oxygen isotope and trace metal analyses near the marine-terminating glacier front.
  4. Figure 4. Samples of deep sea water from the Drake Passage await analysis for dissolved oxygen concentrations.

Who in the Marine Biogeochemistry Group is involved?

Dr Amber Annett; Prof Nicholas Bates; Dr Phyllis Lam; Prof Maeve Lohan; Prof Mark Moore; Prof Toby Tyrrell.

Links to other Research Themes

Chemical, biological and physical controls on primary production in the surface ocean

Vertical export of materials into the ocean's interior and processes in the 'twilight zone'

Dynamics of marine planktonic and microbial communities – from single cells to large scale processes and ecosystem functions

Development of photosynthetic microbes for algal biofuel and other biotechnologies

GEOTRACES - An International Study of the Marine Biogeochemical Cycles of Trace Elements and Isotopes

Bermuda Institute of Ocean Sciences

Ocean currents and mixing

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