Kitz Florian, Gerdel Katharina, Hammerle Albin, Laterza Tamara, Spielmann Felix M, Wohlfahrt Georg
Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
Oecologia. 2017 Mar;183(3):851-860. doi: 10.1007/s00442-016-3805-0. Epub 2017 Jan 9.
During recent years, carbonyl sulfide (COS), a trace gas with a similar diffusion pathway into leaves as carbon dioxide (CO), but with no known "respiration-like" leaf source, has been discussed as a promising new approach for partitioning net ecosystem-scale CO fluxes into photosynthesis and respiration. The utility of COS for flux partitioning at the ecosystem scale critically depends on the understanding of non-leaf sources and sinks of COS. This study assessed the contribution of the soil to ecosystem-scale COS fluxes under simulated drought conditions at temperate grassland in the Central Alps. We used transparent steady-state flow-through chambers connected to a quantum cascade laser spectrometer to measure the COS and CO gas exchange between the soil surface and the atmosphere. Soils were a source of COS during the day, emissions being mainly driven by incoming solar radiation and to a lesser degree soil temperature. Soil water content had a negligible influence on soil COS exchange and thus the drought and control treatment were statistically not significantly different. Overall, daytime fluxes were large (12.5 ± 13.8 pmol m s) in their magnitude and consistently positive compared to the previous studies, which predominantly used dark chambers. Nighttime measurements revealed soil COS fluxes around zero, as did measurements with darkened soil chambers during daytime reinforcing the importance of incoming solar radiation. Our results suggest that abiotic drivers play a key role in controlling in situ soil COS fluxes of the investigated grassland.
近年来，羰基硫（COS）作为一种痕量气体，其进入叶片的扩散途径与二氧化碳（CO₂）相似，但尚无已知的类似“呼吸”的叶片来源，已被视为一种将生态系统尺度的净CO通量划分为光合作用和呼吸作用的有前景的新方法。COS在生态系统尺度上用于通量划分的效用关键取决于对COS非叶片源和汇的理解。本研究评估了在中阿尔卑斯山温带草原模拟干旱条件下土壤对生态系统尺度COS通量的贡献。我们使用连接到量子级联激光光谱仪的透明稳态流通室来测量土壤表面与大气之间的COS和CO₂气体交换。白天土壤是COS的一个来源，排放主要由入射太阳辐射驱动，土壤温度的影响较小。土壤含水量对土壤COS交换的影响可忽略不计，因此干旱处理和对照处理在统计学上无显著差异。总体而言，与之前主要使用暗室的研究相比，白天通量的幅度较大（12.5±13.8 pmol m⁻² s⁻¹）且始终为正。夜间测量显示土壤COS通量接近零，白天用 darkened soil chambers进行的测量也是如此，这强化了入射太阳辐射的重要性。我们的结果表明，非生物驱动因素在控制所研究草原的原位土壤COS通量方面起着关键作用。
