The influence of oceanic ozone uptake on volatile organic compound production and air–sea exchange

Phillips, Daniel (2022) The influence of oceanic ozone uptake on volatile organic compound production and air–sea exchange. Doctoral thesis, University of East Anglia.

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Abstract

This thesis focuses on the influence of oceanic ozone uptake on volatile organic compound (VOC) production, with the intention to reduce uncertainties in the ocean sink of ozone and source/sink of VOCs.

In the first data chapter, eddy covariance measurements of the air–sea fluxes of acetone, acetaldehyde and dimethylsulfide from a coastal observatory in the south-west UK are presented. Acetaldehyde and acetone show clear atmospheric deposition from both an open-water sector and a terrestrially influenced marine sector, while dimethylsulfide shows oceanic emission. Measured bulk fluxes agree reasonably well and are used to derive air–sea transfer velocities. Measured fluxes are compared to global flux estimates.

In the second data chapter, production yield measurements of acetaldehyde, acetone and isoprene from the ozone oxidation of seawater (containing marine dissolved organic matter, DOM) are presented from coastal seawater (south-west UK) over spring, summer and autumn. Experiments with phytoplankton culture and fatty acids provide evidence for a biological DOM precursor. Scaling the laboratory production yield data to the global ocean showed these reactions contribute a significant production of isoprene, which may account for the long-standing discrepancy between the top-down and bottom-up estimates of oceanic isoprene sources. The production of acetaldehyde and acetone were relatively less important from a global budget perspective.

In the third data chapter, measurements of the relative ozone loss to seawater in the Atlantic Ocean are presented. Measurements of iodide concentration and experiments with iodide standards are used to determine the contribution of iodide and DOM to surface ozone loss and results suggest near-equal contributions from these two reactant pools. Depth measurements suggest latitudinal variability due to the Antarctic waters. A coastal time series of ozone loss and VOC production is used to draw further conclusions about the linkage between ocean ozone uptake and the resultant VOC source.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Kitty Laine
Date Deposited:	07 Dec 2022 17:17
Last Modified:	07 Dec 2022 17:40
URI:	https://ueaeprints.uea.ac.uk/id/eprint/89992
DOI:

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