Emission of climate relevant volatile organochlorines by plants occurring in temperate forests

Chlorine, one of the most abundant elements in nature, undergoes a complex biogeochemical cycle in the environment, involved in the formation of volatile organochlorines (VOCls), which in turn can contribute to environmental problems, contaminate natural ecosystems, and are of public health concern. Several industrial and natural sources of VOCls have already been identified; however, data – particularly on the natural sources – are still scarce. The aim of this study was to investigate the diversity of emission of VOCls from soil and several undergrowth plants collected in temperate spruce forest ecosystem and the effect of salting on the VOCl emission of plants. Undergrowth plants were found to emit chloroform (CHCl3) in the range of 2.2–201 pmol/day/g dry weight (DW), tetrachloromethane (CCl4) 0–23.5 pmol/day/g DW, and tetrachloroethene (C2Cl4) 0–13.5 pmol/day/g DW; the average emission rates were about 10 times higher than that of soil (2.9–47.2; 0–5.8; 0–3.6 pmol/day/g DW of CHCl3; CCl4; C2Cl4 emission, respectively). Addition of sodium chloride solution in most cases caused an increase in the emission of CHCl3 and caused a species specific – effect on the emissions of CCl4 and C2Cl4. The results suggest that the emission of VOCls from spruce forest contribute to the atmospheric input of reactive chlorine; however, on a global scale it is only a minor net source.