Evidence for marine production of monoterpenes

Abstract

Environmental context. Laboratory incubation experiments and shipboard measurements in the SouthernAtlantic Ocean have provided the first evidence for marine production of monoterpenes. Nine marine phytoplankton monocultures were investigated using a GC-MS equipped with an enantiomerically-selective column and found to emit monoterpenes including (−)-/(+)-pinene, limonene and p-ocimene, all of which were previously thought to be exclusively of terrestrial origin. Maximum levels of 100-200 pptv total monoterpenes were encountered when the ship crossed an active phytoplankton bloom. Abstract.Laboratory incubation experiments and shipboard measurements on the SouthernAtlantic Ocean have provided the first evidence for marine production of monoterpenes. Nine marine phytoplankton monocultures were investigated using a GC-MS equipped with an enantiomerically-selective column and found to emit at rates, expressed as nmol Monoterpenes were detected in marine air sufficiently far from land as to exclude influence from terrestrial sources. Maximum levels of 100-200 pptv total monoterpenes were encountered when the ship crossed an active phytoplankton bloom, whereas in low chlorophyll regions monoterpenes were mostly below detection limit.

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

“…As already discussed, mixing ratios of isoprene (Sinha et al, 2007;Yassaa et al, 2008) and monoterpenes (Yassaa et al, 2008) have been reported to reach in the region of hundreds of pptv over active phytoplankton blooms in the marine boundary layer. Additionally, the emission of small alkenes from coastal waters has been observed (Lewis et al, 1999).…”

“…While the vast majority of these emissions are from terrestrial sources, there are also biogenic emissions in coastal and remote marine environments, associated with seaweed and phytoplankton blooms (Moore et al, 1994). Isoprene mixing ratios (as well as those of some monoterpenes) have been reported to reach hundreds of pptv (parts per trillion by volume) over active phytoplankton blooms in the marine boundary layer (Sinha et al, 2007;Yassaa et al, 2008), with the potential to impact local air quality (Williams et al, 2010). Removal of isoprene from the troposphere is dominated by reaction with the OH radical during the day and reaction with the nitrate radical during the night (Calvert et al, 2000).…”

Evaluation of the global oceanic isoprene source and its impacts on marine organic carbon aerosol

“…Such a large source would produce atmospheric isoprene concentrations over the remote oceans orders of magnitude larger than observed. These findings suggest a nondominant role for isoprene in driving OC abundances in the remote Southern Ocean, implying an alternative source from primary OC aerosol emission or oxidation of other ocean-emitted volatile organics such as monoterpenes (Yassaa et al, 2008).…”

Ship-based detection of glyoxal over the remote tropical Pacific Ocean

“…Assuming an OH concentration of 3 × 10 6 molec/cm 3 and an atmospheric life time of CHO-CHO of 2 h (conservative upper limit), the VOC concentration needed to explain 100 ppt of CHOCHO is either 600 ppt of isoprene, 2.8 ppb toluene, or 8.9 ppb acetylene, or lower concentrations if multiple compounds were present. There are few observations of VOCs over the remote open ocean, and most of them focus on isoprene (Bonsang et al, 1992;Broadgate et al, 1997Broadgate et al, , 2004Baker et al, 2000;Matsunaga et al, 2002;Meskhidze and Nenes, 2006;Yassaa et al, 2008). The currently measured isoprene concentrations do not exceed 40 ppt and mostly are on the order of 10 ppt.…”