Methyl iodide production in the open ocean.

Stemmler, I., Hense, I., Quack, Birgit and Maier-Reimer, E. (2014) Methyl iodide production in the open ocean. Open Access Biogeosciences (BG), 11 (16). pp. 4459-4476. DOI 10.5194/bg-11-4459-2014.

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Abstract

Production pathways of the prominent volatile organic halogen compound methyl iodide (CH3I) are not fully understood. Based on observations, production of CH3I via photochemical degradation of organic material or via phytoplankton production has been proposed. Additional insights could not be gained from correlations between observed biological and environmental variables or from biogeochemical modeling to identify unambiguously the source of methyl iodide. In this study, we aim to address this question of source mechanisms with a three-dimensional global ocean general circulation model including biogeochemistry (MPIOM-HAMOCC (MPIOM - Max Planck Institute Ocean Model HAMOCC - HAMburg Ocean Carbon Cycle model)) by carrying out a series of sensitivity experiments. The simulated fields are compared with a newly available global data set. Simulated distribution patterns and emissions of CH3I differ largely for the two different production pathways. The evaluation of our model results with observations shows that, on the global scale, observed surface concentrations of CH3I can be best explained by the photochemical production pathway. Our results further emphasize that correlations between CH3I and abiotic or biotic factors do not necessarily provide meaningful insights concerning the source of origin. Overall, we find a net global annual CH3I air-sea flux that ranges between 70 and 260 Gg yr(-1). On the global scale, the ocean acts as a net source of methyl iodide for the atmosphere, though in some regions in boreal winter, fluxes are of the opposite direction (from the atmosphere to the ocean).

Document Type: Article
Additional Information: WOS:000341608900013
Keywords: HALOGENATED ORGANIC-COMPOUNDS; MARINE BOUNDARY-LAYER; TO-AIR FLUX; ATLANTIC-OCEAN; PHOTOCHEMICAL PRODUCTION; TROPICAL ATLANTIC; SEA; SEAWATER; HALOCARBONS; MODEL
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-11-4459-2014
ISSN: 1726-4170
Projects: SOPRAN, CliSAP, Future Ocean
Date Deposited: 25 Mar 2014 14:29
Last Modified: 10 Oct 2014 08:27
URI: http://oceanrep.geomar.de/id/eprint/24023

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