School of Natural and Environmental Sciences

Projects

What is the surfactant control of air-sea gas exchange across contrasting biogeochemical regimes?

Improved parameterisation of air-sea gas exchange is an important goal in the science of ocean-atmosphere interaction.  Air-sea gas exchange rates are the product of an air-sea gas concentration difference and a gas transfer velocity (kw) but there is substantial uncertainty over the environmental variability of kw and what controls it.   Indeed, a recent summary of the oceanic uptake of atmospheric CO2 identified lack of knowledge of kw as the largest uncertainty in quantifying the net global air-sea CO2 flux. 

The implications for global models and climate policy are clear and improved kw parameterisations involving important geophysical controls are a clear research need.  One such control of kw is the effect of sea surface surfactants that are mainly by-products of phytoplankton productivity.  Although progress has been made in the laboratory, few studies have been conducted in situ. 

The aim of this project is to establish the extent to which variability in kw between distinct marine “biogeochemical provinces”, as characterised by differences in phytoplankton productivity, are due to variations in surfactant amount and type.   Measurements of surfactant, productivity and other relevant variables will be examined along biological productivity gradients on the UK coastal shelf (North Sea and Western English Channel) and in the Atlantic Ocean between the UK and the Falkland Islands.  At selected sites surface water will be collected and used in short-duration gas exchange tank experiments to examine the variability in kw relating to surfactant and linked indices of primary productivity.