PANGAEA_995280 Year-round CO2, CH4, and N2O fluxes and quality criteria measured with automated chambers along a moisture gradient at Siikaneva bog, Finland (2022) van Delden, Lona; Höse, Anna; Jentzsch, Katharina; Treat, Claire C Year-round CO2, CH4, and N2O fluxes and quality criteria measured with automated chambers along a moisture gradient at Siikaneva bog, Finland (2022) 2026-07-06 PANGAEA Dataset https://doi.pangaea.de/10.1594/PANGAEA.995280 Investigator Lona van Delden lona.van.delden@awi.de Earth Science DATE/TIME Site Carbon dioxide Carbon dioxide, flux Coefficient of determination Root mean square error Data points Carbon dioxide, ambient, average Carbon dioxide, ambient, standard deviation Carbon dioxide, flux, at zero flux condition Methane Methane, flux Methane, ambient, average Methane, ambient, standard deviation Methane, flux, at zero flux condition Nitrous oxide Nitrous oxide, flux Nitrous oxide, ambient, average Nitrous oxide, ambient, standard deviation Nitrous oxide, flux, at zero flux condition Code geoscientificInformation bog Boreal FN-Land_2022_SiikanevaPeatland FN-Land_2022_SiikanevaPeatland_continuous greenhouse gas fluxes Methane moisture gradient Multiple investigations Nitrogen Peatland quality control Gas analyzer, Picarro, G2508 AWI Arctic Land Expedition 2022-01-01 2022-12-31 Complete 61.8372 61.8372 24.1967 24.1967 FluxWIN The role of non-growing season processes in the methane and nitrous oxide budgets in pristine northern ecosystems unrestricted CC-BY-4.0: Creative Commons Attribution 4.0 International English PANGAEA Data Publisher for Earth & Environmental Science https://www.pangaea.de/ Data Center Contact Michael Diepenbroek info@pangaea.de

Leobener Str.

Bremen Bremen 28359 Germany online 344758 data points text/tab-separated-values G2508 Analyzer Datasheet (2024). Picarro, Inc., https://www.picarro.com/g2508_analyzer_datasheet (Accessed 2024) Koskinen, Markku; Minkkinen, Kari; Ojanen, Paavo; Kämäräinen, Matti; Laurila, Tuomas; Lohila, Annalea (2014): Measurements of CO2 exchange with an automated chamber system throughout the year: challenges in measuring night-time respiration on porous peat soil. Biogeosciences, 11(2), 347-363, https://doi.org/10.5194/bg-11-347-2014 Pedersen, A R; Petersen, S O; Schelde, K (2010): A comprehensive approach to soil‐atmosphere trace‐gas flux estimation with static chambers. European Journal of Soil Science, 61(6), 888-902, https://doi.org/10.1111/j.1365-2389.2010.01291.x

This dataset contains year-round measurements of CO2, CH4, and N2O fluxes collected in 2022 using automated chambers along a moisture gradient at Siikaneva bog in southern Finland. Measurements were conducted at three ecosystem types representing different positions along the gradient from upland to wetland: a well-drained upland boreal forest, an intermediate site, and an open bog hollow. Each site was equipped with four automated chambers to provide spatial replication, including three transparent chambers and one opaque chamber. The opaque chamber measures the soil respiration compared to the Net Ecosystem Exchange (NEE) of the transparent chambers. The chambers close one after another fol-lowing a set schedule, alternating the chambers from each microsite for the best spread over the course of the day. A multiplexer switches the sample loop between chambers with several minutes of flush time with ambient air before and after each measurement. The measurement setup allows for 48 separate measure-ments per day for 12 chambers overall, equalling to four fluxes per chamber and day. The chamber system (SUVILUMI OY, Finland) was built and implemented based on the design of Koskinen et al. (2014), who describe the system operations and performance in detail. Briefly, the basic system structure includes a stainless-steel frame with the chamber as moveable lid, a stainless-steel collar inserted 10 cm into the ground, a waterproof actuator (Linak Techline LA-35, Linak, 2009) to move the lid and threaded steel rod legs and bolts, on which the weight of the construction rests. U profiles under the edges of the chamber lids, insulated with foam tape, ensure air-tight sealing. During winter, the frame was lifted to add snow extensions according to the developing snow height. The chambers dimensions are 60 cm x 60 cm x 40 cm (l x w x h; ⁓144 L) to include shrubs. According to the extensions and individual grow-ing vegetation for each replicate, the additional headspace of the collar was added to the chamber head-space by measuring the vegetation or snow height inside the collar on four sides and taking the average. A fan ensures constant mixing of the chamber headspace atmosphere. A pressure vent ensures equalization during changing environmental conditions and sampling. To avoid heat stress on the plants during the day but include traceable changes of lower concentrated gas-es such as CH4 and N2O, we compromised the chamber closure to 10 minutes during summer but extended to 20 minutes during autumn and winter (since 23.09.2022) to increase the detection limit of small fluxes, N2O in particular. During chamber closure time, a headspace gas sample is being transported into a near-by shed through polyurethane tubes by a Picarro internal vacuum pump (flow rate up to 230 sccm) and analyzed immediately by an in-situ Picarro G2508 (Picarro, USA), which measures CO2, CH4, N2O and H2O continuously once per second with cavity ring-down spectroscopy (CRDS). According to the analyzer data sheet by Picarro (2024), the measurement precision at 1 minute and 5 minutes is <10 and <5 ppb for N2O, <7 and <5 ppb for CH4, <300 and <200 ppb for CO2. Afterwards the gas sample is being discarded through a vent (open-loop). This open-loop setup allows for the maximum chamber-to-analyzer distance of 60 m at the upland forest microsite. The lag times resulting from the various sample line lengths was accounted for during the data processing and flux calculation. The flux calculations were done in the R environment (R version 4.1.2). All fluxes are calculated based on their scheduled chamber closure time and converted according to the chamber specific volume and tem-perature during the measurement. Temperature measurements (every 3 seconds) were interpolated to cor-rect the concentration measurements (per second, Hz) before calculating the fluxes by linear regression. Non-linear flux calculation approaches were tested for the data set, such as the HMR package in R (Pedersen, 2010), but due to extreme over- or underestimated fluxes on some occasions, it was decided that the linear fit was overall the better alternative. A flagging procedure provides the data set with informative quality control (QC), which includes three main components. First, system functioning parameters such as line pressure and actuator voltage sig-naled for system failure and flagged the fluxes that were measured at that time. For the second flagging component, the regression coefficient (R2) and the root mean square error (RMSE) were determined for linear fitted fluxes to filter for factors such as dilution, saturation effects or interference. Fluxes of all three gases were flagged when the CO2 concentration R2 over the measurement time frame was below 0.85. Fluxes were also flagged when three times the flux specific RMSE exceeded the RMSE of the no-flux zone per measurement. The no-flux zone was determined by sampling ambient air before and after the meas-urement per chamber per measurement time. Flux measurements close to zero, which fall within the no-flux zone were kept as is and not discarded based on their R2 or RMSE since that would have eliminated all near-zero measurements. The third QC component was based on the field log and visual observations through the Phenocams to exclude times of maintenance or disturbances. ** For all details see the full metadata description at "https://doi.pangaea.de/10.1594/PANGAEA.995280"! ** Alarm code: 1st digit: Picarro warning (True = "2", False= "1") 2nd digit: Actuator fault (<2.5 = "2", otherwise "1") 3rd digit: P_line (<0.5 = "2", otherwise "1") 4th digit: Alarm warning (True = "2", False= "1") 5th digit: Alarm out (True = "2", False= "1") 6th digit: CO2 regression R² (<0.85 = "2", otherwise "1") 7th digit: CO2 RMSE (>3x ambient SD = "2", otherwise "1") 8th digit: CO2 concentration (outside 300-600 µmol/m² = "2", otherwise "1") 9th digit: CH4 concentration (outside 1-3 µmol/m² = "2", otherwise "1") 10th digit: N2O concentration (outside 0.2-0.4 µmol/m² = "2", otherwise "1")

http://en.wikipedia.org/wiki/Coefficient_of_determination Coefficient of determination http://en.wikipedia.org/wiki/ISO_8601 DATE/TIME https://doi.org/10.1111/j.1365-2389.2010.01291.x A comprehensive approach to soil‐atmosphere trace‐gas flux estimation with static chambers https://doi.org/10.5194/bg-11-347-2014 Measurements of CO2 exchange with an automated chamber system throughout the year: challenges in measuring night-time respiration on porous peat soil https://www.awi.de/en/science/junior-groups/fluxwin.html FluxWIN https://www.picarro.com/g2508_analyzer_datasheet G2508 Analyzer Datasheet PANGAEA_993356 DIF 9.4 2026-07-06 2026-07-06