UV-induced emissions of C2–C5 hydrocarbons from leaf litter

Leaf litter is available at many locations at the Earth’s surface. It has the potential to emit many different types of volatile organic compounds (VOCs) into the atmosphere, which may influence local atmospheric chemistry and air quality. In this study, emissions of several C2–C5 hydrocarbons from leaf litter were measured for different plant species and the influence of ultraviolet (UV) radiation on the emissions was determined. Within the ambient range of UV intensities, the emission rates increased linearly with the intensity of the UV radiation. UVB radiation (280–320 nm) was more efficient in the generation of hydrocarbons from leaf litter than UVA (320–400 nm). In the absence of oxygen, no emissions of C2–C5 hydrocarbons were observed. When leaf litter was placed in humid air, emission rates approximately tripled compared with emissions from leaf litter in dry air. Decay of the emission rates was visible on a timescale of months. A simple upscaling showed that UV-induced hydrocarbon emissions from leaf litter might have a small influence on atmospheric chemistry on the local scale, but do not contribute significantly to their global budgets.