Toluene early morning peaks as potential biogenic stress signals of Mediterranean forests
Yáñez Serrano, Ana María (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Lampadariou, Mirto (University of Crete)
Filella, Iolanda (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Llusia, Joan (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Seco, Roger (Institut de Diagnosi Ambiental i Estudis de l'Aigua)
Fernández-Martínez, Marcos (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Portillo-Estrada, Miguel (University of Antwerp)
Mihalopoulos, Nikolaos (University of Crete)
Massagué, Jordi (Institut de Diagnosi Ambiental i Estudis de l'Aigua)
Perez, Noemi (Institut de Diagnosi Ambiental i Estudis de l'Aigua)
Savadkoohi, Marjan (Tecnalia Research & Technology Alliance)
Pandolfi, Marco (Institut de Diagnosi Ambiental i Estudis de l'Aigua)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Querol Carceller, Xavier (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Alastuey, Andrés (Institut de Diagnosi Ambiental i Estudis de l'Aigua)

Date:	2026
Abstract:	Mediterranean forests emit biogenic volatile organic compounds (BVOCs) that significantly influence atmospheric chemistry and ecosystem functioning. Due to high solar radiation and the important anthropogenic emission of atmospheric pollutants in the Western Mediterranean Basin, photochemical activity is enhanced, favouring the formation of ozone and secondary organic aerosols. We measured ambient mixing ratios of volatile organic compounds (VOCs) using Proton Transfer Reaction Mass Spectrometry (PTR-MS) at Montseny Natural Park, a Mediterranean forest 60 km from Barcelona, during summers 2021–2023. Surprisingly, during heat wave conditions, a toluene early morning peak of 0. 23 (interquartile range 0. 18) ppbv was observed. These early morning peaks were associated with prolonged high temperatures (approximately 5 °C higher as compared to non-peak days) and persistently higher vapour pressure deficit (approximately 877 Pa higher as compared to non-peak days), suggesting a potential link to vegetation drought stress. Cross-validation of measurements with Gas Chromatography-Mass Spectrometry (GC-MS) enhanced data reliability. Analysis of the meteorology and the variability of other atmospheric pollutants at the site, allowed to attribute these peaks to a local biogenic origin. These findings suggest that early morning toluene peaks could serve as an indicator of Mediterranean forest vulnerability to climate-induced stressors, with potentially more frequent and intense peaks occurring in the future.
Grants:	European Commission 101076740 Agencia Estatal de Investigación PID2019-108990RB-I00 Generalitat de Catalunya 2021/SGR-00447 Agencia Estatal de Investigación CEX2018-000794-S Agencia Estatal de Investigación CNS2022-135757 Agencia Estatal de Investigación RYC2021-032519-I Agencia Estatal de Investigación PID2022-142160OB-I00 Agencia Estatal de Investigación PID2022-140808NB-I00 "la Caixa" Foundation 100010434 Agencia Estatal de Investigación RYC2021-031511-I Agencia Estatal de Investigación RYC2020-029216-I Agencia Estatal de Investigación PID2021-122892NA-I00
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Published in:	Environmental Science: Atmospheres, April 2026, ISSN 2634-3606

DOI: 10.1039/d5ea00168d

36 p, 2.0 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Research articles
Articles > Published articles