Methanol exchange between grassland and the atmosphere

Abstract

Abstract. Concentrations and fluxes of methanol were measured above two differently managed grassland fields (intensive and extensive) in central Switzerland during summer 2004. The measurements were performed with a proton-transfer-reaction mass-spectrometer and fluxes were determined by the eddy covariance method. The observed methanol emission showed a distinct diurnal cycle and was strongly correlated with global radiation and water vapour flux. Mean and maximum daily emissions were found to depend on grassland species composition and, for the intensive field, also on the growing state. The extensive field with a more complex species composition had higher emissions than the graminoid-dominated intensive field, both on an area and on a biomass basis. A simple parameterisation depending on the water vapour flux and the leaf area index allowed a satisfying simulation of the temporal variation of methanol emissions over the growing phase. Accumulated carbon losses due to methanol emissions accounted for 0.024 and 0.048% of net primary productivity for the intensive and extensive field, respectively. The integral methanol emissions over the growing periods were more than one order of magnitude higher than the emissions related to cut and drying events.

Methanol emissions from maize: Ontogenetic dependence to varying light conditions and guttation as an additional factor constraining the flux

“…Several studies already reported that methanol emission from young leaves of various plant species is several times higher than that from mature leaves (MacDonald and Fall, 1993;NemecekMarshall et al, 1995;Karl et al, 2003;Custer and Schade, 2007;Harley et al, 2007;Hüve et al, 2007;Bracho-Nunez et al, 2011;Hu et al, 2011;Wells et al, 2012). Furthermore, methanol emission was found to be correlated to stomatal conductance (MacDonald and Fall, 1993;Nemecek-Marshall et al, 1995;Niinemets and Reichstein, 2003a), temperature (Schade and Goldstein, 2001;Karl et al, 2003Karl et al, , 2004Karl et al, , 2005Brunner et al, 2007;Custer and Schade, 2007;Hüve et al, 2007;Folkers et al, 2008) and light conditions (Harley et al, 2007;Hüve et al, 2007;Folkers et al, 2008).…”

Deposition fluxes of terpenes over grassland

“…[3] Historically, studies have sought to quantify the dominant compounds emitted from different ecosystems, e.g., terpenes from forested sites [Rinne et al, 2007;Spirig et al, 2005] and methanol from grassland [Bamberger et al, 2010;Brunner et al, 2007;Kirstine et al, 1998]. Terpene emissions by trees are known to be controlled by light (formation by enzymatic reactions), and/or temperature (release from storage pools) depending on the tree species [Niinemets et al, 2004].…”

Abiotic and biotic control of methanol exchanges in a temperate mixed forest

“…Methanol fluxes were computed using block average over 30 min periods, and 2-D rotation was applied. Stationarity test (Foken and Wichura, 1996) was not applied in this study as in Brunner et al (2007), because fluxes would hardly pass the test (more than 40 % of data would have been rejected) and because this filtering did not increase the quality of our methanol data. A filter linked to anthropogenic influence (Sect.…”

“…Among these techniques, disjunct eddy-covariance is the most suitable for long-term monitoring of the ecosystem exchange in real-undisturbed conditions (Rinne et al, 2001). It has been used in several methanol studies (Bamberger et al, 2010;Brunner et al, 2007;Custer and Schade, 2007;Holst et al, 2010;Karl et al, 2001Karl et al, , 2002Karl et al, , 2003Karl et al, , 2004Karl et al, , 2005Langford et al, 2010;Spirig et al, 2005), but none of them (at the exception of Hörtnagl et al, 2011 above a temperate mountain grassland) proposed a year-round follow-up of the exchange. In addition, although methanol dry deposition has been observed occasionally or more regularly in some studies (Custer and Schade, 2007;Holst et al, 2010;Karl et al, 2004Karl et al, , 2005Langford et al, 2010;Schade et al, 2010;Spirig et al, 2005), very few of these studies paid detailed attention to the underlying mechanisms.…”