Source and behavior of isoprenoid compounds at a southern France remote site

To better assess Biogenic Volatile Organic Compounds (BVOC) ambient levels and understand the processes undergone during their transport, a 1-month intensive measurement campaign, involving the monitoring of more than 80 species including isoprenoids (isoprene and 6 monoterpenes), took place in summer 2009 at the remote site of Peyrusse-Vieille, France. multaneous study of monoterpenes and isoprene temporal evolution and meteorological parameters underline two different behaviors, which can be associated to different kind of emissions sources. Thus, isoprene displays characteristics usually associated to local emissions sources; whereas monoterpenes temporal trends would more likely be related to distant ones. Subsequent dispersion models and reactivity studies demonstrated that monoterpenes principally result from the influence of an important regional BVOC emitter: the Landesʹ forest (70 km North-west to the measurement site). ons from Landes forest strongly impact the atmospheric reactivity at the measurement site. Thus, when the measurement site is under the forestʹs plume (Western wind episodes), HO-initiated processes are predominant; whereas O3-induced oxidation processes are observed in other circumstances (north-eastern winds episodes). This dichotomy can be explained by higher in-situ reactivity induced by the upcoming of BVOC from distant sources.