--------------------------------------------- # Data for "Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection" Preferred citation (DataCite format): Gil Loaiza, Juliana; Roscioli, Joseph R.; Shorter, Joanne H.; Volkmann, Till H.M.; Ng, Wei-Ren; Meredith, Laura K.; et al. (2021). Data for "Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection". University of Arizona Research Data Repository. Dataset. https://doi.org/10.25422/azu.data.13383014. Corresponding Author: Laura Meredith, University of Arizona, laurameredith@arizona.edu License: CC BY-NC 4.0 DOI: https://doi.org/10.25422/azu.data.13383014 --------------------------------------------- ## Summary Between 2018 and 2019, we evaluated the integration of a new diffusion-based probe with high-resolution gas trace analyzers using custom soil columns. We measured changes in soil gases, carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitrous oxide (N2O) and its isotopes, and volatile organic compounds (VOCs), through different experiments conducted to challenge the sampling system. Similar sampling systems were built at The University of Arizona (System 1) and Aerodyne Research Inc. (System 2). In System 1, we used Dual-laser TILDAS (Aerodyne Research, Inc. (ARI), Billerica, MA, USA) to measure CO2 isotopes and Mini TILDAS (ARI, Billerica, MA, USA) for CO, and CO2. In System 2, we used a novel dual TILDAS analyzer for isotopomers of methane (CH4) and nitrous oxide (NO2), and Proton Transfer Reaction Time Of Flight Mass Spectrometers (PTR-TOF-MS) vocus (ARI, Billerica, MA, USA) for VOCs (more details: Summary systems experiment and figures.pdf). This data set contains the processed data from the results obtained during the different experiments conducted using controlled columns filled with a simple silica matrix to optimize system parameters and obtain representative soil gas samples. It also contains processed data from experiments using real soil; we challenged the capability of the probe to measure changes in soil conditions by mimicking rainfall to rewet soil and by shifting soil redox from anaerobic to aerobic condition. RStudio and R version 3.3.2 (R Studio Team, 2017) was used to combine raw data and metadata analysis from System 1. Igor Pro (version 7, WaveMetrics, Lake Oswego, OR) was used to analyze instrument diagnostic, concentrations and times series and graphics for both systems. Igor Pro software was used under license. Igor Pro scripts were used for data processing and analysis including Aerodyne Research Inc. proprietary scripts for parsing and averaging data and cannot be in a public repository. Vocus data was processed using the Tofware (Aerodyne/TOFWERK A.G.) software package in Igor Pro. Other portions of Igor code used for plotting are available upon request. Raw measurements files (e.g., TILDAS and vocus spectra which are a large set of data) will be available upon request. We are providing data in ASCII (tab delimited) organized in folders structured as PRO for processed data for specific experiments using System 1 and REA for data data is ready to use for graphic analysis (figures). To guide and increase the understanding about how the data was used, a PDF file with a summary of the experiments and the corresponding REA file was included. --------------------------------------------- ## Files and Folders - Summary systems experiment and figures.pdf/docx: Contains 2 tables that summarize the information and details about System 1 and 2 (Table 1) and the specific experiments conducted to collect the data indicating the corresponding figures (Table 2). #### "Data.zip": Contains data from tests conducted to evaluate the integration of novel porous soil probes and soil trace gas analyzers using customized columns. #### "Data.zip" / "System1_PRO": Data processed from System 1 after using IGOR Pro. General conventions in these files are: Average (Avg), Standard deviation (Sdev), parts per million (ppm), standard cubic centimeters per minute (sccm), Difference between observed and true (diff), Observed data (obs), Calibrated (cal), dilution (dil), col (column-headspace), delta 13CO2 (d13CO2), corrected concentrations for dilution (dil_corr), interpolated (interp). - CO2 Calibration_PRO: Data from measuring known CO2 concentrations to calculate absolute concentration between observed and controlled dilutions. - Calibration co2_dco2_fit_PRO: Used data from "CO2 Calibration_PRO" and applied fitting models for calibration. Results of calibration of absolute concentration of CO2 between observed and controlled dilution mixtures using linear regression (coefficients column P). Results of Gaussian fit of d13C observed - true vs CO2 to calibrate 13CO2 data (Coefficients on Columns R to U). - Experiment 1_PRO: Effect of probe sampling on column test in CO2 and d13CO2. - Experiment 2_increase_PRO: Probe flow dilution test increasing probe flow measuring probe and headspace. - Experiment 2_decrease_PRO: Probe flow dilution test increasing probe flow measuring probe and headspace. - Experiment 3_PRO: Impact of probe pore size on the relationship between probe sampling flow rate and fractional recovery of true soil gas concentrations. Each Column headspace-probe-headspace were measured sequentially in where 62 = column before probe and 64=column after. #### "Data.zip" / "System1_REA": Contains data that has been processed and ready for figures shown in the paper's results section and supplemental information from System 1. General conventions in these files: carbon dioxide (CO2), carbon monoxide (CO), Average (Avg), Standard deviation (Sdev), Difference between observed and true (diff), Observed data (obs), Calibrated (cal), dilution (dil), col (column), delta 13CO2 (d13CO2), corrected concentrations for dilution (dil_corr), interpolated (interp). - Figure 4_data_Experiment 1: Effect of probe flow rate on column gas concentration - Figure 6_data_Experiment 2: Probe and headspace CO2 over a range of probe flow rates and dilution ratios - Figure 7_data_Experiment 2: Impact of probe sampling flow rate on the fractional recovery of true gas concentrations by probe gas sampling for CO and CO2. - Figure 8_data_Experiment 2: Impact of probe sampling flow rate on the fractional recovery of true CO2 concentrations and the offset in ẟ13C. - Figure 10_data_Experiment 3: Impact of probe pore size on the relationship between probe sampling flow rate and fractional recovery of true soil gas concentrations. - Figure S1_data_Calibration CO2 - Figure S2_data_Concentration dependent deltaCO2 Cal #### "Data.zip" / "System2_REA": Contains processed data from System 2 shown in figures in the paper's results section. General conventions: nitrous oxide (N2O), methane (CH4), methane isotope: (13C-CH4), nitrous oxide isotopes: 14N14N16O (“δ446”), 14N15N16O (“δ456”), 15N14N16O (“δ546”), and 14N14N18O (“δ448”), site-preference of N2O (SP) - Figure 5_data_Experiment 2: Evaluating the impact of Headspace and probe measurements in N2O concentrations using silica in System 2 - Figure 9_data_Experiment 3: Evaluating the capability of using multiprobe setting to sequentially measured headspace-probe-headspace for N2O including isotopic ratios for three N2O isotopomers 𝛿456, 𝛿546, 𝛿448, and CH4 and 13C-CH4 - Figure 11_data_Experiment 4: Evaluating the impact of probe sampling flow rate, pore size, trace gas species, and soil matrix on the fractional recovery of true soil gas concentrations. - Figure 12_data_Experiment 5: Quantifying changes on N2O, its isotopic signatures, and site preference as a response to soil rewet. - Figure 13_data_Experiment 6: Evaluating the capability of the probe and the sampling system to capture changes in N2O, CO2, and VOC in real-time as a response to changes in soil redox conditions (from anaerobic to aerobic). For these experiments, PTR-TOF-MS was not quantitatively calibrated for the signals reported below, as we were only interested in relative concentration responses to wetting. Thus, signals are reported in non-normalized counts/s (Hz).