Biogenic hydrocarbons in the atmospheric boundary layer: A review

Nonmethane hydrocarbons are ubiquitous trace atmospheric constituents yet t hey control the oxidation capacity of the atmosphere. Both anthropogenic an d biogenic processes contribute to the release of hydrocarbons to the atmos phere. In this manuscript, the state of the science concerning biosynthesis , transport, and chemical transformation of hydrocarbons emitted by the ter restrial biosphere is reviewed. In particular, the focus is on isoprene, mo noterpenes, and oxygenated hydrocarbons. The generated science during the l ast 10 years is reviewed to explain and quantify hydrocarbon emissions from vegetation and to discern impacts of biogenic hydrocarbons on local and re gional atmospheric chemistry. Furthermore, the physiological and environmen tal processes controlling biosynthesis and production of hydrocarbon compou nds are reported on. Many advances have been made on measurement and modeli ng approaches developed to quantify hydrocarbon emissions from leaves and f orest ecosystems. A synthesis of the atmospheric chemistry of biogenic hydr ocarbons and their role in the formation of oxidants and aerosols is presen ted. The integration of biogenic hydrocarbon kinetics and atmospheric physi cs into mathematical modeling systems is examined to assess the contributio n of biogenic hydrocarbons to the formation of oxidants and aerosols, there by allowing us to study their impacts on the earth's climate system and to develop strategies to reduce oxidant precursors in affected regions.