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Ashu-Ayem, ER,Nitschke, U,Monahan, C,Chen, J,Darby, SB,Smith, PD,O'Dowd, CD,Stengel, DB,Venables, DS
2012
October
Environmental Science & Technology
Coastal Iodine Emissions. 1. Release of I-2 by Laminaria digitata in Chamber Experiments
Published
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Optional Fields
MARINE BOUNDARY-LAYER ENHANCED ABSORPTION-SPECTROSCOPY MOLECULAR-IODINE CHLOROPHYLL FLUORESCENCE ATMOSPHERIC CHEMISTRY NEAR-ULTRAVIOLET CROSS-SECTIONS GAS-PHASE IN-SITU SEAWEED
46
10413
10421
Tidally exposed macroalgae emit large amounts of I-2 and iodocarbons that produce hotspots of iodine chemistry and intense particle nucleation events in the coastal marine boundary layer. Current emission rates are poorly characterized, however, with reported emission rates varying by 3 orders of magnitude. In this study, I-2 emissions from 25 Laminaria digitata samples were investigated in a simulation chamber using incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS). The chamber design allowed gradual extraction of seawater to simulate tidal emersion of algae. Samples were exposed to air with or without O-3 and to varying irradiances. Emission of I-2 occurred in four distinct stages: (1) moderate emissions from partially submerged samples; (2) a strong release by fully emerged samples; (3) slowing or stopping of I-2 release; and (4) later pulses of I-2 evident in some samples. Emission rates were highly variable and ranged from 7 to 616 pmol min(-1) gFW(-1) in ozone-free air, with a median value of 55 min(-1) gFW(-1) for 20 samples.
DOI 10.1021/es204534v
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