Ocean micronutrient cycles: UK GEOTRACES

Lead Research Organisation: University of Southampton
Department Name: School of Ocean and Earth Science

Abstract

A paradigm developed during the 20th Century that the amount and type of life in the oceans depended to a large degree on the supply to the surface ocean of three nutrients - phosphate, nitrate, and silica (the macronutrients). International research efforts mapped the distribution of these macronutrients in detail and developed a full understanding of how these macronutrients are chemically cycled into, out-of, and within the oceans. Models of ocean biology and the global carbon cycle now incorporate this understanding. In the early 1990s, however, it became clear that this view of ocean nutrients was incomplete. New ability to sample seawater without contaminating it, and to make sensitive measurements, demonstrated that a range of metals, present at low concentrations in seawater, were required by life. Of these 'micronutrients', the most prominent is iron which is now known to be the major limitation on life in large areas of the ocean. Other micronutrients, such as zinc and cobalt, are also essential for critical biological processes. Despite their importance, our knowledge of the chemical cycle of these micronutrients is rudimentary, particularly compared to that of the macronutrients. We know micronutrients enter the ocean in dust, but the size of other inputs (from rivers, alteration of sediments, or from undersea volcanoes) is not known. Even the distribution of these micronutrients in the ocean is poorly known and measurements are sparse, particularly in the deep ocean. To understand controls on life and the carbon cycle in the ocean, there is an urgent need to dramatically improve knowledge of the distribution and cycling of micronutrients. This is the goal of a major new international research programme - GEOTRACES. The programme seeks to develop an understanding of micronutrient cycles as comprehensive as that of the macronutrients, through a series of sections spanning all the ocean basins. This proposal represent the UK contribution to that programme. We will map the concentration of the seven most important micronutrients through the full water column along an east-west section at 40oS in the Atlantic. This ocean is little studied but is an important region for ocean biogeochemical cycles. In the surface at this latitude the ocean is very productive, requiring addition of micronutrients, but the source of these micronutrients is not known. At depth are found three different water masses. The uppermost flows northwards and upwells to the surface at the equator to provide micronutrients to this very productive region, while the middle layer flows southward before upwelling in the Southern Ocean where low iron supply is known to be the primary limitation on life. Understanding micronutrient inputs to these deep water masses is therefore important for life in a much broader region, and will teach us generally about the processes that control cycling of micronutrients into surface and deep waters around the globe. We will study the inputs of micronutrients from four ocean boundaries - from the atmosphere as dust blown from South America; from rivers (the large Plata River); from sediments; and from the active volcanoes found in the mid Atlantic. We will use a variety of tools - including other chemicals that act as tracers of the micronutrients, and computer models - to assess how micronutrients get from their sources into the open ocean. And we will study the relationship between these micronutrients and the nature of the ecosystems that occur in the productive seas of 40oS. This work will rely on co-operation between 10 leading UK institutes, including universities and research centres, and also involves leading scientists from other countries (partially through the GEOTRACES programme). This national and international effort will lead to a significant improvement in our understanding of the cycles of the metals that control the biology and carbon system in the ocean.

Publications

10 25 50
 
Description Results available so far cover the eastern half of the South Atlantic basin. The results indicate that the South African margin supplies a smaller amount of iron to the ocean continental margins than in other areas studied. This is significant because iron is a biologically essential micronutrient with the potential to enhance (if available) or restrict (if scarce) the amount of phyotosynthetic productivity in the surface ocean, and thus the amount of CO2 drawn down into this region of the ocean.
Exploitation Route Climate prediction helps UK strategy These results will provide essential data inputs to models of carbon cycling between the oceans and atmosphere, and therefore refine climate model predictions.
Sectors Environment

URL http://www.ukgeotraces.com
 
Description See policy impact evidence uploaded
First Year Of Impact 2018
Sector Environment
Impact Types Policy & public services

 
Description Citation in Environment Audit Committee report
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
Impact The EAC Committee report urges Government action to stop using seas as a sewer. Specific impact of my contribution included a statement that Govt should commit not to pursue licences for seafloor massive sulfides within UK jurisdiction. The UK should use its significant influence to impose a moratorium on licences outside UK jurisdiction and work with the International Seabed Authority to ensure robust Environmental Impact Assessments that are based on the precautionary principle and make the best use of available scientific evidence.
URL https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/980/980.pdf
 
Description Free Online Course: Exploring our Oceans 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Exploring our Oceans has reached a global audience (over 35,000 sign ups), and our learners have a wide range of backgrounds and motivations for taking the course.

The course design and FutureLearn platform ensures accessibility for all. Videos introduce key concepts at a basic level, and accompanying text expands on video content. Extended reading opportunities and links to external organisations, provide signposting for broader learning and
engagement. Links to open access papers stretch participants for deeper advanced learning.

Our postgraduate facilitators develop their public engagement skills and confidence via asynchronous discussion of emotive subjects within the community. Delivering such a course has enabled the Faculty to test new technologies and activities at scale before use with on-campus students.
Nelson Mandela University is a contributor to the course as part of a Newton grant (ESRC: ES/N013913/1 Capacity building and PhD student partnership with Nelson Mandela University in the Marine and Maritime sectors, 2015-2018). Part of the legacy of this project includes sharing learning resources and capacity building for developing online learning in South Africa. Summary of Impacts • Maintained a significant 4 year presence on a global online platform
• Boosted applications to undergraduate programmes and engaged with our incoming students during the recruitment cycle
• Promoted our research in deep sea exploration
• Built on a 4*REF2014 Impact Case Study: Exploring the Deep: Public Engagement with Deep Ocean Research and provided clear metrics on reach and impact of learner experience.
• Developed our graduate students' skills in communication, impact and engagement
• Delivered our Newton funded project goals to transform marine postgraduate education in South Africa in partnership with Nelson Mandela University,
• Helped to build our international partnerships worldwide
Year(s) Of Engagement Activity 2014,2015,2016,2017,2018
URL https://www.futurelearn.com/courses/exploring-our-oceans
 
Description Life Scientific BBC Radio 4 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview with Jim Al-Khalili discussing all elements of current and past funding and impact.
Year(s) Of Engagement Activity 2018
URL https://www.bbc.co.uk/programmes/b0b6m5y3