Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

[摘要] Measuring in situ soil fluxes of carbon dioxide ( CO₂ ), methane ( CH₄ ), and nitrous oxide ( N₂O ) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO₂ flux chamber system (LI-8100A) with a CH₄ and N₂O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 min was sufficient for a reliable estimation of CO₂ and CH₄ fluxes (100 % and 98.5 % of fluxes were above minimum detectable flux – MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N₂O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 min was more appropriate for reliable estimation of most N₂O fluxes (85.6 % of measured fluxes are above MDF ± 0.002 nmol m ⁻² s ⁻¹ ). Our study highlights the importance of adjusted closure time for each gas.

[学科分类] 地球化学与岩石