Enowmbi R. Ashu-Ayem, Udo Nitschke, Ciaran Monahan, Jun Chen, Steven B. Darby, Paul D. Smith, Colin D. O’Dowd, Dagmar B. Stengel, and Dean S. Venables

2012

Environmental Science and Technology

Coastal Iodine Emissions. 1. Release of I2 by Laminaria digitata in Chamber Experiments

Published

WOS: 15 ()

46

10413

10421

Tidally exposed macroalgae emit large amounts of I2
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, I2 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 O3
and to varying irradiances. Emission of I2 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 I2 release; and (4) later pulses of I2 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 pmol min−1 gFW−1 for 20 samples.

http://hdl.handle.net/10468/787

10.1021/es204534v