Seawater isoprene loss and production rates across contrasting oceanic regions

Measured biological variables and isoprene process rate constants across contrasting regions of the global ocean. SST: sea surface temperature; SSS: sea surface salinity; ZML: mixed layer depth; U10 24h: wind speed at 10 m above sea surface, averaged over 24 hours; chla: chlorophyll-a concentration; BA: bacterial abundance; kloss: rate constant of isoprene loss in incubations (microbial degradation + chemical oxidation); kvent: rate constant of isoprene ventilation to the atmosphere; kmix: rate constant of isoprene vertical mixing by turbulent diffusion at the bottom of the mixed layer (negative means import into the surface mixed layer); total τ: turnover time due to all sinks; kprod: rate constant of isoprene production, assuming 24-h steady state for the isoprene concentration; sp. prod. rate: chla-normalized daily rate of isoprene production.

Results of the coastal seawater dark incubations for isoprene loss kinetics. SST: lab-incubation temperature (within ±0.5ºC of the in-situ temperature); chla: chlorophyll-a concentration; isoprene concentration; std err: standard error of duplicate isoprene concentration measurements. The experiments were conducted with water from the Blanes Bay Microbial Observatory (coastal NW Mediterranean) and the coral reef lagoon of Moorea (French Polynesia).

Results of the coastal seawater dark incubations for isoprene oxidation assays. SST: in-situ and incubation temperature; chla] chlorophyll-a concentration; isoprene concentration.