Global uptake of carbonyl sulfide (COS) by terrestrial vegetation: Estimates corrected by deposition velocities normalized to the uptake of carbon dioxide (COsub2/sub)

摘要

COS uptake by trees, as observed under dark/light changes and underapplication of the plant hormone abscisic acid, exhibited a strongcorrelation with the CO₂ assimilation rate and the stomatalconductance. As the uptake of COS occurred exclusively through the stomatawe compared experimentally derived and re-evaluated deposition velocities(V_d; related to stomatal conductance) for COS and CO₂. We show that V_d of COS is generallysignificantly larger than that of CO₂. We therefore introduced thisattribute into a new global estimate of COS fluxes into vegetation. The newglobal estimate of the COS uptake based on available net primary productivitydata (NPP) ranges between 0.69-1.40 Tga-1. However, as a COS moleculeis irreversibly split in contrast to CO₂ which is released again byrespiration processes, we took into account the Gross Primary Productivity(GPP) representing the true CO₂ leaf flux the COS uptake has to berelated to. Such a GPP based deposition estimate ranged between 1.4-–2.8 Tga-1 (0.73-1.50 TgSa-1).We believe that in order to obtain accurate global COS sink estimates such a GPP-based estimate corrected bythe different deposition velocities of COS and CO₂ must be taken into account.