Biogenic VOCs in continental Northern Europe—Concentrations and photochemistry

Abstract

This work is part of the project Biogenic VOC Emissions and Photochemistry in the Boreal regions of Europe (BIPHOREP). A short overview is first given of the project activities. This paper specifically deals with ambient air VOC and ozone concentrations. Both biogenic emissions and photochemical processes have strong seasonal cycles. The emission of biogenic VOCs (isoprene and terpenes) takes place mainly between May and October. Average ozone concentrations have a spring maximum and, in the northern parts of the boreal region, a minimum in late summer. Photochemical ozone production takes place in March–October. Elevated ozone concentrations are observed in spring and summer in connection with favourable meteorological situations. Analysis of ozone and total nitrate concentrations together with a factor analysis of C2–C6 VOC concentrations show that the concentrations of anthropogenic compounds are elevated when ozone concentrations are above the background level. However, also the compounds with biogenic origin show higher concentrations then, because elevated ozone concentrations are connected with warm continental air masses. Factor analysis suggests that 1-butene, propene and ethene have also biogenic sources.