Oxygenated volatile organic compounds
Oxygenated volatile organic compounds (OVOCs) are gases which
have a short lifetime in the atmosphere and include commonly known
chemicals, such as methanol, ethanol and acetone. OVOCs are of
environmental importance because they significantly influence the
chemistry of the atmosphere, including ozone formation, even when
they are present at very low concentrations.
The surface ocean acts as a reservoir for OVOCs but, due to the
high solubility of these gases in seawater, very few field studies
have been performed. Indeed for some OVOCs it is still not clear
whether the ocean acts as a source to the atmosphere or as a
sink.
As well as general research into OVOCs, PML is investigating
whether these compounds are important as a source of energy and /
or organic carbon for the growth of microbes, particularly in areas
of the ocean where other sources of carbon for growth may be in
short supply.
PML has built two novel systems to measure concentrations of
OVOCs. Experiments on the SOLAS ICON cruise during 2009 have shown
excellent agreement between the various systems for the measurement
of acetone and acetaldehyde. Further to this, PML has also
developed techniques to quantify the amount of energy and carbon
that bacteria obtain from OVOC compounds in the ocean. This has
shown that OVOCs are important sources of organic carbon for
bacteria in nutrient limited areas of the ocean.
Future work will focus on defining the magnitude of the
ocean-atmosphere flux of OVOCs to assess whether the supply of
these compounds, from the atmosphere, may be an important source of
biologically active carbon for the ocean.
Projects
- Atlantic Meridional Transect
(AMT)
The Atlantic Meridional Transect is a
multidisciplinary programme, co-ordinated by PML, which undertakes
biological, chemical and physical oceanographic research during an
annual voyage between the UK and destinations in the South
Atlantic, a distance of up to 13,500km. This transect crosses a
range of ecosystems from sub-polar to tropical and from euphotic
shelf seas and upwelling systems to oligotrophic mid-ocean
gyres.
- Surface Ocean Lower Atmosphere Study (SOLAS) ICON
cruise
The aim of the upwelling cruise, SOLAS-ICON,
was to determine the hydrodynamics of an upwelling plume off the NW
African coast, in order to characterise its impact upon the
physical, photochemical and microbiological processes contributing
to ocean-atmosphere exchange of biogenic gases.
-
Surface Ocean Lower Atmosphere Study (SOLAS) Investigation
of the Near Surface Production of Iodocarbons: Rates and Exchanges
(INSPIRE) cruise
The INSPIRE cruise focused on the tropical
Atlantic (around Cape Verde), studying the production of trace
gases that contain iodine. A combination of water column
sampling and incubation studies were carried out in order to
measure iodocarbon concentrations in the water and
determine the amount being emitted to the
atmosphere.