Abstract
Isoprene is an important biogenic volatile organic compound (BVOC), with a contribution to annual greenhouse gas emissions similar to that of methane in terms of carbon equivalent. Isoprene is mostly produced by terrestrial vegetation, although marine ecosystems also play an important role in isoprene production. Here, we report isoprene fluxes from warm temperate seagrass communities dominated by specific seagrass species (Posidonia australis, Zostera muelleri and Halophila ovalis) in Wallis Lake, NSW, Australia, and from tropical seagrass communities (H. ovalis/Halodule uninervis mixed patches) on Lizard Island, QLD, Australia. P. australis and Z. muelleri were net isoprene sinks (-0.6 ± 0.1 and -3.4 ± 2.0 nmol m-2 h-1, respectively), whereas H. ovalis (2.4 ± 0.2 nmol m-2 h-1) and mixed patches of H. ovalis/H. uninervis (13.2 ± 3.2 nmol m-2 h-1) were a net source of isoprene, indicating that seagrass communities can be both a source of and a sink for isoprene on a local scale depending on species. Overall, isoprene effluxes were more than 5 times higher on Lizard Island than in Wallis Lake, likely due to higher temperatures and prolonged sunlight on Lizard Island during the time of measurement. Wallis Lake and Lizard Island seagrass communities emit isoprene to the water column at an average rate of -0.3 and 8 mg m-2 yr-1, respectively. Seagrass communities are a benthic source of isoprene in coastal waters, but only make a small contribution (2.3 Gg C yr-1) to the global marine isoprene flux (11.6 Tg C yr-1).
Highlights
Isoprene is one of the most important biogenic volatile organic compounds (BVOCs) on the planet, with emissions similar to those of methane in terms of carbon equivalents (Arneth et al 2007, Menon et al 2007)
With about 50% of secondary organic aerosol (SOA) formation in the atmosphere being due to isoprene photooxidation (Claeys et al 2004, Liao et al 2007)
The hydroxy-driven oxidation of isoprene enhances particle growth and increases the capacity of aerosols to act as cloud condensation nuclei (CCN), causing a negative feedback loop in sea surface warming via the production
Summary
Isoprene is one of the most important biogenic volatile organic compounds (BVOCs) on the planet, with emissions similar to those of methane in terms of carbon equivalents (Arneth et al 2007, Menon et al 2007). While isoprene has traditionally been considered a terrestrial gas, with 90% of the isoprene on Earth being released into the atmosphere by vegetation (Guenther et al 1995), it is well established that marine ecosystems play an important role in isoprene production (Alcuna Alvarez et al 2009, Arnold et al 2009, Exton et al 2013). Algal biomass drives isoprene production (Bonsang et al 1992, Yokouchi et al 1999), whereas in shallow, benthic marine habitats close to the coast, microbial communities are the major drivers of isoprene concentrations (Alcuna Alvarez et al 2009, Shaw et al 2010, Exton et al 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
