XVI International Botanical Congess

Organic acids, mainly formic and acetic acid, are of relevance for atmospheric chemistry, as they have a dominant impact on the acidity within precipitation in remote as well as industrial regions. Sources for organic acids are still under investigation. Biogenic emissions from vegetation, directly and indirectly, have a dominant role within the budget of tropospheric organic acids. For the indirect emission from vegetation, volatile hydrocarbons are discussed as most important compounds which can be oxidized to deliver organic acids. Recently published extensive studies show that vegetation can also be regarded as a direct emitter of both formic and acetic acids. Estimates of global annual emissions range between 1 to 6 Tg formic acid and 0.6 to 2 Tg acetic acid. Such release rates reflect a 15-30% contribution by direct forest emissions to the European continental organic acid budget.