The effect of ozone on the emission of carbonyls from leaves of adult <i>Fagus sylvatica</i>

Abstract

ABSTRACT Under the site conditions of a temperate forest, the exchange of short‐chained oxygenated carbonyls (aldehydes, ketones) was assessed from leaves of adult European beech trees. The crowns of the trees were either exposed to an elevated O 3 regime as released by a free‐air fumigation system (2 × O 3 ) or to the unchanged O 3 regime at the site (1 × O 3 , ‘control’). Daily fluctuations of oxygenated carbonyls were quantified in relation to environmental and physiological factors. In particular, the effect of O 3 on carbonyl exchange was studied. Measurements of leaf gas exchange were performed with a dynamic cuvette system, and carbonyl fluxes were determined using 2,4‐dinitrophenylhydrazine (DNPH)‐coated silica gel cartridges. Leaves mainly emitted acetaldehyde, formaldehyde and acetone. Acetaldehyde dominated the emissions, amounting up to 100 nmol m −2 min −1 , followed by formaldehyde (approximately 80 nmol m −2 min −1 ) and acetone (approximately 60 nmol m −2 min −1 ). Carbonyl emissions were highest during midday and significantly lowered at night, irrespective of the O 3 exposure regime. Trees exposed to 2 × O 3 emitted acetaldehyde and acetone at enhanced rates. The findings are of particular significance for future climate change scenarios that assume increased O 3 levels.