Observations of the uptake of carbonyl sulfide (COS) by trees under elevated atmospheric carbon dioxide concentrations

Abstract

Abstract. Global change forces ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO 2 ). We understand that carbonyl sulfide (COS), a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzymes which are metabolizing CO 2 , i.e. ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEP-Co) and carbonic anhydrase (CA). Therefore, we discuss a physiological/biochemical acclimation of these enzymes affecting the sink strength of vegetation for COS. We investigated the acclimation of two European tree species, Fagus sylvatica and Quercus ilex, grown inside chambers under elevated CO 2 , and determined the exchange characteristics and the content of CA after a 1-2 yr period of acclimation from 350 ppm to 800 ppm CO 2 . We demonstrate that a compensation point, by definition, does not exist. Instead, we propose to discuss a point of uptake affinity (PUA). The results indicate that such a PUA, the CA activity and the deposition velocities may change and may cause a decrease of the COS uptake by plant ecosystems, at least as long as the enzyme acclimation to CO 2 is not surpassed by an increase of atmospheric COS. As a consequence, the atmospheric COS level may rise causing an increase of the radiative forcing in the troposphere. However, this increase is counterbalanced by the stronger input of this trace gas into the stratosphere causing a stronger energy reflection by the stratospheric sulfur aerosol into space (Brühl et al., 2012). These data are very preliminary but may trigger a discussion on COS uptake acclimation to foster measurements with modern analytical instruments.

Dimethyl sulfide in the Amazon rain forest

“…For example, in previous studies, maximum DMS emissions from Platanus orientalis were found to be 0.42 pmol m À2 s À1 [Geng and Mu, 2006], whereas Hibiscus sp. was reported to emit DMS at a maximum rate of 26 pmol m À2 s À1 [Yonemura et al, 2005].…”

“…DMS emission measurements have been reported from soils and leaf litter [Kesselmeier and Hubert, 2002;Lamb et al, 1987;Staubes et al, 1989;Yang et al, 1996] with possible sources from the microbial metabolism of sulfur-containing amino acids [Banwart and Bremner, 1975;Zhang et al, 2004]. Although DMS emissions have also been reported from vegetation [Fall et al, 1988;Geng and Mu, 2006;Jardine et al, 2010a;Kanda and Tsuruta, 1995;Kesselmeier et al, 1993;Yonemura et al, 2005], ecosystem-scale observations remain extremely rare, leaving large uncertainties with regard to the potential importance of terrestrial DMS sources. While plant surveys revealed that most plants studied emit only small amounts of DMS to the atmosphere [Geng and Mu, 2006;Yonemura et al, 2005], large DMS emission rates that increased with light and temperature have been reported from a rainforest tree species in Cameroon [Kesselmeier et al, 1993], agricultural plants like corn [Fall et al, 1988], rice paddies [Zhigang et al, 2008], and the desert plant creosotebush [Jardine et al, 2010a].…”

“…Although DMS emissions have also been reported from vegetation [Fall et al, 1988;Geng and Mu, 2006;Jardine et al, 2010a;Kanda and Tsuruta, 1995;Kesselmeier et al, 1993;Yonemura et al, 2005], ecosystem-scale observations remain extremely rare, leaving large uncertainties with regard to the potential importance of terrestrial DMS sources. While plant surveys revealed that most plants studied emit only small amounts of DMS to the atmosphere [Geng and Mu, 2006;Yonemura et al, 2005], large DMS emission rates that increased with light and temperature have been reported from a rainforest tree species in Cameroon [Kesselmeier et al, 1993], agricultural plants like corn [Fall et al, 1988], rice paddies [Zhigang et al, 2008], and the desert plant creosotebush [Jardine et al, 2010a]. Nonetheless, model simulations suggest that globally, terrestrial DMS sources are small (7% of total) compared to marine phytoplankton sources (85% of total) [Kettle and Andreae, 2000;Watts, 2000].…”

Bryophyte gas‐exchange dynamics along varying hydration status reveal a significant carbonyl sulphide (COS) sink in the dark and COS source in the light

“…Furthermore, the utility of COS as a tracer of GPP depends heavily on the assumption that the flux of COS between the atmosphere and the leaf is one-way and driven by CA activity alone. This assumption has been validated at the leaf level for certain species and environmental conditions (Stimler et al, 2010;Sandoval-Soto et al, 2012). However, recent field studies have shown that COS emissions from wheat leaves may occur during senescence and from deciduous forests during periods of high temperature and drought (Maseyk et al, 2014;Commane et al, 2015).…”

Carbonyl sulfide (OCS) exchange between soils and the atmosphere affected by soil moisture and compensation points

“…Vegetation was considered as the main sink for OCS, and the close relationship between OCS uptake and photosynthetic CO2 uptake lead to a considerable increase of the sink strength estimates based on GPP (Sandoval-Soto et al, 2005). Furthermore, changes of the sink strength of vegetation as a response to global change is a matter of discussion (White et al, 2010;Sandoval-Soto et al, 2012).…”