Articles | Volume 17, issue 17
Research article
14 Sep 2017
Research article |  | 14 Sep 2017

Oxygenated volatile organic carbon in the western Pacific convective center: ocean cycling, air–sea gas exchange and atmospheric transport

Cathleen Schlundt, Susann Tegtmeier, Sinikka T. Lennartz, Astrid Bracher, Wee Cheah, Kirstin Krüger, Birgit Quack, and Christa A. Marandino

Abstract. A suite of oxygenated volatile organic compounds (OVOCs – acetaldehyde, acetone, propanal, butanal and butanone) were measured concurrently in the surface water and atmosphere of the South China Sea and Sulu Sea in November 2011. A strong correlation was observed between all OVOC concentrations in the surface seawater along the entire cruise track, except for acetaldehyde, suggesting similar sources and sinks in the surface ocean. Additionally, several phytoplankton groups, such as haptophytes or pelagophytes, were also correlated to all OVOCs, indicating that phytoplankton may be an important source of marine OVOCs in the South China and Sulu seas. Humic- and protein-like fluorescent dissolved organic matter (FDOM) components seemed to be additional precursors for butanone and acetaldehyde. The measurement-inferred OVOC fluxes generally showed an uptake of atmospheric OVOCs by the ocean for all gases, except for butanal. A few important exceptions were found along the Borneo coast, where OVOC fluxes from the ocean to the atmosphere were inferred. The atmospheric OVOC mixing ratios over the northern coast of Borneo were relatively high compared with literature values, suggesting that this coastal region is a local hotspot for atmospheric OVOCs. The calculated amount of OVOCs entrained into the ocean seemed to be an important source of OVOCs to the surface ocean. When the fluxes were out of the ocean, marine OVOCs were found to be enough to control the locally measured OVOC distribution in the atmosphere. Based on our model calculations, at least 0.4 ppb of marine-derived acetone and butanone can reach the upper troposphere, where they may have an important influence on hydrogen oxide radical formation over the western Pacific Ocean.

Short summary
For the first time, oxygenated volatile organic carbon (OVOC) in the ocean and overlaying atmosphere in the western Pacific Ocean has been measured. OVOCs are important for atmospheric chemistry. They are involved in ozone production in the upper troposphere (UT), and they have a climate cooling effect. We showed that phytoplankton was an important source for OVOCs in the surface ocean, and when OVOCs are emitted into the atmosphere, they could reach the UT and might influence ozone formation.
Final-revised paper