- 1School of Physics & Environmental Research Institute, University College Cork, Cork, Ireland
- 2Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
The release of molecular iodine (I2) from the oceans into the atmosphere has been recognized to correlate strongly with ozone depletion events and aerosol formation in the marine boundary layer [1,2]. The detailed mechanisms and dominant sources leading to the observed concentrations of I2 and IO in the marine troposphere are still under investigation. One prime source of I2 are brown macro-algae (kelp) such as Laminaria digitata, which release molecular iodine when under oxidative stress [3].
In order to further advance the understanding of I2 exchange processes between the sea and atmosphere near the coast, it is essential to map the spatial and temporal distribution of I2 over the shoreline. For that purpose we developed a low power (~20 W), compact, and light weight (~4 kg) instrument for the deployment in field trials on mobile platforms, including unmanned aerial vehicles. The instrument uses incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) [4] for I2 detection, with a molecule-specific 3𝜎 detection limits of 48 pptv in 1 s, as demonstrated under laboratory conditions.
In this presentation, we outline the mechanical, optical, and electronic design of the instrument and discuss its general engineering features. Laboratory measurements of I2 emitted by Laminaria digitata will be presented together with future applications and envisaged field deployments of the instrument.
Acknowledgement: This work is supported by Research Ireland (21/FFP-A-8973, AtmoTrace)
[1] A. Saiz-Lopez, J.M.C. Plane, Novel iodine chemistry in the marine boundary layer, Geophys. Res. Lett. 31, L04112 (2004).
[2] G. McFiggans et al., Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine, Atmos. Chem. Phys. 4, 701–713 (2004).
[3] S. Dixneuf et al., The time dependence of molecular iodine emission from Laminaria digitata, Atm. Chem. Phys. 9, 823–829 (2009).
[4] S.E. Fiedler et al. Incoherent broad-band cavity-enhanced absorption spectroscopy, Chem. Phys. Lett. 371, 284–294 (2003).
Key words: Marine boundary layer, iodine I2, iodine oxide IO, macro-algae, cavity enhanced absorption spectroscopy.
How to cite: Saito, S., Womack, C., Brown, S., and Ruth, A.: A compact light weight instrument for in situ detection of I2 in the marine boundary layer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13660, https://doi.org/10.5194/egusphere-egu25-13660, 2025.
