The flux of carbonyl sulfide and carbon disulfide between the atmosphere and a spruce forest

[摘要] Turbulent fluxes of carbonyl sulfide(COS) and carbon disulfide (CS₂) were measured over a spruce forest inCentral Germany using the relaxed eddy accumulation (REA) technique. A REA sampler was developed and validated usingsimultaneous measurements of CO₂ fluxes by REA and by eddy correlation. REA measurements were conducted during six campaignscovering spring, summer, and fall between 1997 and 1999. Both uptake and emission ofCOS and CS₂ by the forest were observed, with deposition occurring mainly during the sunlitperiod and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The averagefluxes for COS and CS₂ are-93 ± 11.7 pmol m^-2s^-1 and-18 ± 7.6 pmol m^-2 s^-1, respectively. The fluxes ofboth gases appear to be correlated to photosynthetically active radiation and to theCO₂ and \chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gasesis controlled by stomata. An uptake ratio COS/CO₂ of 10 ± 1.7pmol mmol^-1 has been derived from the regression line for the correlation between theCOS and CO₂ fluxes. This uptake ratio, if representative for theglobal terrestrial net primary production, would correspond to a sink of2.3 ± 0.5 Tg COS yr^-1.

[学科分类] 大气科学