Isotopic composition of CO emitted by plants under the influence of light and temperature

Abstract

In this study, the influence of light and temperature on plant emitted carbon monoxide has been investigated. This was done by using a dynamical sampling method directly connected to a CO isotope measurement system. Plant material was put into a quartz reactor and was either irradiated with light or the reactor was heated in an oven. Emission rates and isotopic composition of C and O isotopes have been determined. Light experiments have been performed with fresh leaves and dried leaves. All plants showed emission of CO when irradiated with solar simulated light. Fresh plants showed an average δ 13 C value of 43.67 ± 3.64 ‰ and an average δ 18 O of 26.14 ± 4.25 ‰. Drying of the plants decreased the δ 18 O value. Additionally the influence of UV was investigated by blocking UVB with a glass plate or blocking UVA and UVB with a transparent plastic plate. These tests showed that blocking UVA and UVB decreases the emission and increases the δ 13 C value. Temperature increase to 30 - 50 °C also induced CO emission from leaves. The results of the temperature experiments showed large variability in terms of emission rate and isotopic composition. It is suggested that temperature but also the storage time of plant material increases the δ 13 C value.