Prochlorococcus marinus as a source of marine methyl iodide (CH sub(3)I)
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The ocean is the dominant source of atmospheric methyl iodide (CH sub(3)I) which, through photolytic release of iodine, plays a significant role in stratospheric ozone destruction. The mechanisms of CH sub(3)I production in the marine environment are poorly understood. A previous laboratory and field study suggested Prochlorococcus marinus, a ubiquitous marine cyanobacterium, is a globally significant biological producer of CH sub(3)I (Smythe-Wright et al, 2006, Global Biogeochem. Cycles, 20). In this study, CH sub(3)I concentrations were measured in cultures of P. marinus (MED4) and Synechococcus. Cell-normalized production rates in P. marinus cultures ranged from 2 to 5 molecules of CH sub(3)I cell super(-1) d super(-1); these rates were 1000 fold lower than production rates reported for the previous study. Extrapolating CH sub(3)I production rates from the current study yields a global production rate of 0.7 Gg yr super(-1) which accounts for 0.6% of the estimated global CH sub(3)I production, suggesting P. marinus is not a globally significant source of CH sub(3)I.
Brownell, D., R. Moore, and J. Cullen. "Prochlorococcus marinus as a source of marine methyl iodide (CH sub(3)I)." CMOS Congress 2009 - Sea and Sky Come to Life, Halifax, Nova Scotia (Canada), 31 May - 4 June 2009.