Articles | Volume 17, issue 12
Research article
22 Jun 2017
Research article |  | 22 Jun 2017

Effect of mid-term drought on Quercus pubescens BVOCs' emission seasonality and their dependency on light and/or temperature

Amélie Saunier, Elena Ormeño, Christophe Boissard, Henri Wortham, Brice Temime-Roussel, Caroline Lecareux, Alexandre Armengaud, and Catherine Fernandez

Abstract. Biogenic volatile organic compounds (BVOCs) emitted by plants represent a large source of carbon compounds released into the atmosphere, where they account for precursors of tropospheric ozone and secondary organic aerosols. Being directly involved in air pollution and indirectly in climate change, understanding what factors drive BVOC emissions is a prerequisite for modeling their emissions and predict air pollution. The main algorithms currently used to model BVOC emissions are mainly light and/or temperature dependent. Additional factors such as seasonality and drought also influence isoprene emissions, especially in the Mediterranean region, which is characterized by a rather long drought period in summer. These factors are increasingly included in models but only for the principal studied BVOC, namely isoprene, but there are still some discrepancies in estimations of emissions. In this study, the main BVOCs emitted by Quercus pubescens – isoprene, methanol, acetone, acetaldehyde, formaldehyde, MACR, MVK and ISOPOOH (these three last compounds detected under the same mz) – were monitored with a PTR-ToF-MS over an entire seasonal cycle during both in situ natural and amplified drought, which is expected with climate change. Amplified drought impacted all studied BVOCs by reducing emissions in spring and summer while increasing emissions in autumn. All six BVOCs monitored showed daytime light and temperature dependencies while three BVOCs (methanol, acetone and formaldehyde) also showed emissions during the night despite the absence of light under constant temperature. Moreover, methanol and acetaldehyde burst in the early morning and formaldehyde deposition and uptake were also punctually observed, which were not assessed by the classical temperature and light models.

Short summary
We investigated the BVOC emissions variations of Quercus Pubescens, under natural and amplified drought, in situ, in order to determine the dependency to light and/or temperature of these emissions. Our results showed that all BVOC emissions were reduced with amplified drought. Moreover, we highlighted two dependences: (i) light and temperature and (ii) light and temperature during the day and to temperature during the night. These results can be useful to enhance emission models.
Final-revised paper