Chloroform emissions from arctic and subarctic ecosystems in Greenland and Northern Scandinavia
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The aim of our study was to estimate emissions of natural chloroform from soil in arctic and subarctic ecosystems. We therefore determined the seasonal and spatial variation in soil-to-air fluxes of chloroform at 11 sites representing typical vegetation types in Greenland (Narsarsuaq, Kangerlussuaq and Disko Island) and northern Scandinavia (Abisko). Fluxes of chloroform showed a large variation, ranging from 4 to 2850 ng m−2 h−1. The local variation within a 12-m transect at each site was frequently five to tenfold, which emphasizes the need for multiple measurements even within field plots that seem homogenous. At one site, the transect was extended to 58 m and 40 measurements and a large number of environmental parameters were recorded as well. In this transect, collars separated by 60 cm distances were in most cases similar but at 3 m distance variation was as big as between collars with greater separation. CO2 flux was the parameter that showed the most correlation to the chloroform flux in the extended transect. Chloroform fluxes also varied over the year, but this variation was smaller than the variation between the five collars of each site and much smaller than the variation between sites. All arctic sites except a non-tussock sedge wetland showed low fluxes. A subarctic pine forest had by far the highest fluxes. Subarctic and boreal coniferous forests generally seem to be important global sources of biogenic chloroform to the troposphere. The future spatial extent of coniferous forest in the subarctic to arctic region, in response to climate change, may be the key driver of future chloroform emissions from these areas.
KeywordsChloroform Flux Spatial variation Soil Transect Arctic
This study was funded by the Villum Foundation through the project Natural emissions of volatile organohalogens in arctic and subarctic terrestrial systems—a study of the Arctic’s role in the atmospheric organohalogen budget (ArctiVOX, Grant No. 9934). Co-funding and logistic support was provided by Center for Permafrost (CENPERM, Copenhagen University, Danish National Research Foundation Grant No. CENPERMDNRF100). We also greatly acknowledge the logistic support from the staffs at Abisko Scientific Research Station (Royal Swedish Academy of Sciences), the Ice Patrol (Narsarsuaq, Danish Meteorological Institute) and Kangerlussuaq International Science Support.
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