Bottom boundary layer mediation of chemical fluxes from ocean margins

Marine sediments are an important source of essential micronutrients to the ocean, but measuring these inputs is problematic. I aim to observe and understand the behavior of micronutrient inputs, in particular iron, close to the seafloor, where exchanges between sediments and seawater are thought to mediate the uptake of carbon via photosynthesis in the surface ocean. Refining this critical source to the ocean is needed to improved ocean-coupled models of the Earth's climate. A key aspect of this work will be to collect samples of dissolved and suspended particulate material in vertical transects close to the seabed, where the physical mixing and chemical exchanges in the ocean are completely different from the ocean interior.
Chemical processes in this 'bottom boundary layer' are largely unknown, because sampling it from the ocean surface is difficult; large distances from a research vessel propagates inaccuracy close to the seafloor and risks damage or loss of costly equipment. A novelty of this project will be to develop and optimize a free-falling instrument that can rest remotely on the seabed and collect bottom water and particulate samples across a 10 to 100 meter thick layer of the ocean using remote and autonomous controls. The instrument will be developed with support from the Ocean Technology and Engineering Group at the National Oceanography Centre, with additional funds from the Royal Society provided by Prof. Gideon Henderson at the University of Oxford.
The new instrument will be first used in conjunction with the NERC Shelf Sea Biogeochemistry Programme in the UK North Atlantic planned for late 2014. Observed conditions will be simulated in laboratory experiments to identify chemical exchange mechanisms between sediments and seawater. The fellowship will benefit from analytical expertise at the Marine Trace Element Laboratory of University of South Carolina, USA, through which newly developed metal isotope observations in seawater will be made.
Future deployments of the new instrument are planned within the lifetime of this fellowship through interaction with the international GEOTRACES program. A legacy of this work will be to refine estimates of micronutrient supply from ocean margins to improve ocean climate models, and to establish an operational platform for a broad range of chemical observations across an under-explored part of the Earth system. Potential research avenues for the future include refining chemical tracers of ocean processes; monitoring marine habitats and contaminant transport processes; and observing chemical processes at the seafloor in dynamic ice-covered or volcanic regions of the ocean over time.

Marine sediments are an important source of essential micronutrients to the ocean, but measuring these inputs is problematic. I aim to observe and understand the behavior of micronutrient inputs, in particular iron, close to the seafloor, where exchanges between sediments and seawater are thought to mediate the uptake of carbon via photosynthesis in the surface ocean.

Refining this critical source to the ocean is now a priority in government-funded research in nations around the world (e.g. GEOTRACES and the World Climate Research Program's Climate Variability and Predictability Project); Results will improve the accuracy of ocean-coupled general circulation models (GCMs) of the Earth's climate, which are the fundamental basis of weather and climate prediction tools - on all resolution and time scales - used both operationally for day-to-day forecasting, and for the longer term seasonal, decadal and centennial modeling that underpins the work on the IPCC assessment reports. It's clear, therefore, that climate and meteorological agencies, such as the UK Met Office Hadley Centre, charged with the projection of future climate as well as the development of the next generation of coupled climate models, should be interested in the results. There is enormous public interest in climate change and the ocean is a key component in the earth's climate system. Whether through the frequency and magnitude of extreme weather events such as flooding, hot summers or the impact of the NAO on the likelihood of snowy UK winters, there is much in my Fellowship which could have an impact on UK public policy (e.g. the Met Office's current 'get ready for winter' programme), the insurance industry (extreme climate event attribution), or the quality of life of the UK public ('hot' summers, or 'snowy' winters). There is additional impact on sustainability of UK fishing and agriculture; Human activity has enhanced the discharge of harmful elements into the oceans and knowledge of the processes regulating trace elements will improve prediction of contaminant transport and fate of contaminants in the ocean; thereby helping to protect the marine environment.


Impact related milestones and measures of success I intend to deliver during the tenure of this Fellowship include:

1) Publication of results in international peer-reviewed journals (as open access).
2) Presentation of results at international and national conferences.
3) Launching of a Fellowship and personal research website.
4) Incorporation of science outputs from my Fellowship research into outreach, education, and learning activities via the the University of Oxford and elsewhere.
5) Regular participation in local science blogs and news features on international websites.
6) Successfully attracting young Earth Science undergraduates into PhDs in NERC science areas related to the topic of my Fellowship.

No specific additional costs are requested or required. The routine impacts described will be delivered within the main fieldwork and analytical budget outlined in the justification for resources. Non-academic impacts will be provided at no additional cost to NERC.