A Lagrangian biogeochemical study of an eddy in the Northeast Atlantic

• Published in: Progress in Oceanography
• Main Authors: Jickells, TD, Liss, PS, Broadgate, W, Turner, S, Kettle, AJ, Read, J, Baker, K, Cardenas, LM, Carse, F, Hamren-Larssen, M, Spokes, L, Steinke, M, Thompson, A, Watson, A, Archer, SD, Bellerby, RGJ, Law, CS, Nightingale, PD, Liddicoat, MI, Widdicombe, CE, Bowie, AR, Gilpin, LC, Moncoiffe, G, Savidge, G, Preston, T, Hadziabdic, P, Frost, T, Upstill-Goddard, R, Pedros-Alio, C, Simo, R, Jackson, A, Allen, A, DeGrandpre, MD
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd. 2008
• Subjects: Earth Sciences; Oceanography; Oceanography not elsewhere classified; Northeast Atlantic
• Online Access: http://www.sciencedirect.com; https://doi.org/10.1016/j.pocean.2008.01.006; http://ecite.utas.edu.au/57212

We report the results of an experiment in the Northeast Atlantic in which sulphur hexafluoride (SF6) was releasedwithin an eddy and the behaviour of trace gases, nutrients and productivity followed within a Lagrangian framework overa period of 24 days. Measurements were also made in the air above the eddy in order to estimate airsea exchange rates forsome components. The physical, biological and biogeochemical properties of the eddy resemble those of other eddies studiedin this area, suggesting that the results we report may be applicable beyond the specific eddy studied. During a period oflow wind speed at the start of the experiment, we are able to quantitatively describe and balance the nutrient and carbonbudgets for the eddy. We also report concentrations of various trace gases in the region which are similar to those observedin other studies and we estimate exchange rates for several trace gases. We show that the importance of gas exchange overother loss terms varies with time and also varies for the different gases. We show that the various trace gases considered(CO2, dimethyl sulphide (DMS), N2O, CH4, non-methane-hydrocarbons, methyl bromide, methyl iodide and volatile seleniumspecies) are all influenced by physical and biological processes, but the overall distribution and temporal variabilityof individual gases are different to one another. A storm disrupted the stratification in the eddy during the experiment,resulting in enhanced nutrient supply to surface waters, enhanced gas exchange rates and a change in plankton community,which we quantify, although overall productivity was little changed. Emphasis is placed on the regularity of storms in thetemperate ocean and the importance of these stochastic processes in such systems.