BOREAS TGB-01 Soil CH4 and CO2 Profile Data from NSA Tower Sites Summary: The BOREAS TGB-01 team made numerous measurements of trace gas concentrations and fluxes at various NSA sites. This data set contains methane (CH4) and carbon dioxide (CO2) concentrations in soil profiles from the NSA-OJP, NSA-OBS, NSA-YJP, and NSA-BP sites during the period of 23-May to 20-Sep-1994. The soil gas sampling profiles of CH4 and CO2 were completed to quantify controls on CO2 and CH4 fluxes in the boreal forest. The data are provided in tabular ASCII files. Table of Contents * 1. Data Set Overview * 2. Investigator(s) * 3. Theory of Measurements * 4. Equipment * 5. Data Acquisition Methods * 6. Observations * 7. Data Description * 8. Data Organization * 9. Data Manipulations * 10. Errors * 11. Notes * 12. Application of the Data Set * 13. Future Modifications and Plans * 14. Software * 15. Data Access * 16. Output Products and Availability * 17. References * 18. Glossary of Terms * 19. List of Acronyms * 20. Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS TGB-01 Soil CH4 and CO2 profiles from NSA OJP, YJP, and OBS 1.2 Data Set Introduction The Trace Gas Biogeochemistry (TGB)-01 team took soil gas profiles at the BOReal Ecosystem Atmosphere Study (BOREAS) Northern Study Area (NSA) Old Jack Pine (OJP), Young Jack Pine (YJP), Old Black Spruce (OBS), and Beaver Pond (BP) sites during the growing season of 1994. Some of the soil samplers were placed in the ground during the summer of 1993 to ensure equilibration. Portable samplers were used at sites where no permanent soil gas samplers were installed. The soil gas samples were analyzed for CO2 and CH4. At some of the OBS and BP sites, the soil/peat was saturated. At these sites, water samples were taken and analyzed for CH4 and CO2. 1.3 Objective/Purpose Soil gas sampling profiles of CH4 and CO2 were completed to quantify controls on CO2 and CH4 fluxes in the boreal forest. 1.4 Summary of Parameters The data contain measurements of the soil pore concentrations of CH4 and CO2. The data were measured at the soil surface and at different depths (5-93 cm below the surface) at the various locations. Most of the profiles correspond with collar flux measurements. 1.5 Discussion The soil gas profiles were taken at varying depths from 0 to 93 cm below the surface, where the surface (0 cm) is designated as the top of the vegetated ground cover. At some sites, groups of samplers were permanently embedded in the ground to ensure consistency of sampling location. The OBS site was divided into two different sets of data; one with aluminum chambers, and one with plastic chambers. The OBS site where Patrick Crill (TGB-01) measured fluxes with aluminum chambers and collars had permanent samplers associated with each aluminum collar flux measurement. The OBS site where Dean Moosavi (TGB-01) measured fluxes with plastic chambers and collars had soil gas profiles taken with a portable sipper associated with each of the plastic collar flux measurements. Moosavi also measured the BP site fluxes, and the associated profiles were measured with a portable sipper. The OJP site had a nest of permanent sippers associated with each aluminum flux collar. The YJP site had only one nest of permanent sippers; therefore, it was to be associated with all aluminum collar flux measurements at that site. 1.6 Related Data Sets BOREAS TGB-01 CO2 and CH4 Chamber Flux Data over the NSA BOREAS TGB-03 CO2 and CH4 Chamber Flux Data over the NSA BOREAS TGB-03 Soil CO2 and CH4 Profile Data over the NSA BOREAS TGB-05 CO2 and CH4 Chamber Flux Data over the NSA 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Patrick M. Crill Research Associate Professor University of New Hampshire 2.2 Title of Investigation Magnitude and Control of Trace Gas Exchange in Boreal Ecosystems 2.3 Contact Information Contact 1 Dr. Patrick M. Crill Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-3519 (603) 862-0188 (fax) Contact 2 Sadredin (Dean) C. Moosavi Graduate Student Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-2927 (603) 862-0188 (fax) Contact 3 Ruth K. Varner Research Scientist Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-2939 (603) 862-0188 (fax) Contact 4 Sara K, Golightley Raytheon STX Corporation NASA/GSFC Greenbelt, MD (301) 286-2624 sgolight@pop900.gsfc.nasa.gov 3. Theory of Measurements CH4 and CO2 measurements of soil pore gas and/or water can provide constraints and implications for flux controls at the surface (Crill, 1991). The profile measurements will enable the scientist to determine if the uptake/flux is occurring in a particular soil depth range. 4. Equipment 4.1 Sensor/Instrument Description Shimadzu GC-14A, FID and TCD CO2 was quantified with a Shimadzu GC-14A Gas Chromatograph (GC) with a thermal conductivity detector (TCD) operated at 70 degrees C after separation on a HayeSepQ column at 40 degrees C using ultrapure (99.999%) He as a carrier gas flowing at 30 mL/min. CH4 was quantified with a Shimadzu GC-14A or a Shimadzu GC-MINI2 with a flame ionization detector (FID) operated at 125 degrees C after separation on a HayeSepQ column at 40 degrees C using ultrapure (99.999%) N2 as a carrier gas flowing at 30 mL/min. Analog signals (0-1 V) from the detectors were digitized at 10 Hertz (Hz) with a Hewlett Packard (HP) 35000D A/D board and quantified and logged using HP ChemStation software. 4.1.1 Collection Environment Samples were collected under ambient conditions. 4.1.2 Source/Platform Soil and water. 4.1.3 Source/Platform Mission Objectives The mission objective was to quantify the CO2 and CH4 soil profile concentrations present in the boreal forest NSA. 4.1.4 Key Variables CH4 and CO2 concentrations were the key variables measured at different depths in the soil or peat profile. 4.1.5 Principles of Operation The Shimadzu GC-14A is equipped with a hydrogen FID and a TCD. The FID is used to measure CH4, while the TCD is used to quantify CO2. The FID uses a hydrogen flame in an air atmosphere to burn components as they exit the column. In the flame, carbon-carbon bonds are fragmented so that various organic ions and free electrons exist. Application of a voltage across a collector electrode over the flame causes an ion current to flow, which is amplified and then measured as the output signal. The TCD elutes CO2 by flowing a sample in a helium carrier gas past metallic filaments with current flowing through them. The sample components with lower thermal conductivity than the helium carrier gas raise the filament temperature when they pass through. The signal output from the TCD is a measurement of the change in filament resistance caused by the temperature rise. The signal output from both the FID and TCD is for a data processor, integrator, recorder, or computer (Instruction Manual: GC-14A; Shimadzu Corporation, Kyoto, Japan). The GC-MINI2 was equipped with a FID and operated in the same manner as the GC-14A FID. 4.1.6 Sensor/Instrument Measurement Geometry Not applicable. 4.1.7 Manufacturer of Sensor/Instrument Manufacturer of GC-14A FID/TCD and GC-MINI2 Shimadzu Scientific Instruments, Inc. 7102 Riverwood Drive Columbia, MD 21046 (410) 381-1227 The investigator manufactured the samplers. 4.2 Calibration Signal peaks from the detectors were quantified with working standards calibrated against Canadian AES (Canadian Atmospheric Environment Services) certified primary standards acquired by the BOREAS project and a CO2/ CH4 standard of Niwot Ridge air prepared by National Oceans and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Laboratory (CMDL). 4.2.1 Specifications None given. 4.2.1.1 Tolerance The sensitivity of the TCD is approximately 6,000 mV mL/mg. The FID's maximum sensitivity is 3*10-12 grams/second for diphenyl. 4.2.2 Frequency of Calibration The instrument was calibrated on a daily basis. Standards were run generally before and after samples on a given day of analysis. 4.2.3 Other Calibration Information Signal peaks from the detectors were quantified with working standard calibrated against Canadian Atmospheric Environment Services (AES) certified primary standards acquired by the BOREAS project and a CO2/CH4 standard of Niwot Ridge air prepared by the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Laboratory (CMDL). 5. Data Acquisition Methods Soil profile samples were taken from different depths at the YJP, OJP lichen and moss, and OBS (Patrick Crill) sites with soil gas samplers (sippers) installed in August 1993. The sippers are fabricated from 50 cm of high-efficiency stainless steel 1/8-inch tubing with small holes drilled along the last 10 cm. A hole was dug in the ground, and the stainless steel tubing was placed horizontally in the soil profile. Polypropylene tubing attached the steel tubing to the surface, and allowed for sampling. The polypropylene tubing was fitted with a polycarbonate/nylon stopcock at the surface. Soil air was sampled using the polycarbonate/nylon stopcock and 60-mL polypropylene syringes. A portable soil gas sipper was used at the OBS (Dean Moosavi), BP, and the OJP sites. It was constructed with the same materials as the installed sippers. Prior to sampling, 10 mL of soil air was discarded to avoid contamination from ambient air. After discarding the initial 10 mL of soil air, a 30-mL soil air sample was taken. The syringes were fitted with rubber bands to prevent any leaking in of ambient air and were transported to the lab for analysis on the GC-14A FID/TCD and/or the MINI-2 FID. In some cases when the soil/peat was saturated, the samples were taken as water samples. Prior to sampling, 10 mL of soil pore water was discarded to avoid contamination from ambient air. After the initial 10 mL of soil pore water was discarded, a 30-mL soil pore water sample was taken. In the lab, the syringes were filled to 60 mL with ultra high-purity nitrogen. The syringes were shaken for 2 minutes to allow the dissolved CH4 and CO2 to enter the air space. This method is described by McAuliffe, 1971. The air in the syringe was then removed from the 60-mL syringe with a 10-mL glass syringe and run on the GC-14A FID/TCD and/or the MINI-2 FID. 6. Observations 6.1 Data Notes No major problems with GC. 6.2 Field Notes For the soil profiles completed with the aluminum chamber fluxes (Patrick Crill): 20Jun94 - OBS, soil profile at collars OBS 5 and OBS 6; couldn't draw the 30-cm sample. 27Jun94 - OBS, soil profile at collars OBS 5 and OBS 6; couldn't draw the 30-cm or 25-cm samples. 04Jul94 - Figured out that there is permafrost at collars OBS 5 and OBS 6 at 25- 30 cm. 04Jul94 - No 30-cm sample at collars OBS 7 and OBS 8. 04Jul94 - No 30-cm sample at collars OBS 9 and OBS 10. 10Jul94 - No 30-cm sample at YJP; too rocky. 16Jul94 - No 25- or 30-cm samples at YJP; too rocky. 20Jul94 - Permafrost at OBS collar 5 at 25 and 30 cm; permafrost at OBS collar 9 at 20, 25, and 30 cm. 23Jul94 - No profile samples for YJP 3. 26Jul94 - OBS 5 has permafrost below 15-cm; no 20-, 25-, or 30-cm samples. 30Jul94 - No profile samples at YJP 1 or YJP 3. 01Aug94 - OBS 5 still has permafrost below 20 cm. 07Aug94 - No profile samples after 15 cm at YJP 1; no profile samples for YJP 3. 08Aug94 - OBS 5 has permafrost below 25 cm. 14Aug94 - All profiles complete from OBS; no permafrost at 5 anymore! 30Aug94 - OBS 5 and OBS 6 show water at 20 cm in soil profile. 30Aug94 - OBS 9 and OBS 10 show water at 30 cm in soil profile. For the soil profiles completed with the plastic chamber fluxes (Dean Moosavi): 16May94 - OJP moss site profile frozen at 13- and 24-cm depths. 19May94 - BP profiles: collar 19 frozen below 25 cm; collar 21 frozen below 10 cm; collar 27 frozen below 20 cm. 20May94 - OBS collar 6 frozen below 10 cm; OBS collar 8 frozen below 20 cm. 22May94 - OJP moss profile frozen at 13 and 24 cm. 25May94 - OBS collar 9 frozen below 15 cm; OBS collar 8 frozen below 25 cm; OBS collar 6 frozen below 15 cm; OBS collar 1 profile frozen below 20 cm. 26May94 - BP collar 22 frozen below 10 cm; BP collar 19 frozen below 10 cm; the pond and mire sites had water at the surface, so the entire profiles were water samples. 27May94 - OBS lichen site profile frozen below 15 cm; OBS water site profile frozen below 15 cm; OBS coast profile frozen below 15 cm; OBS collars 13-16 were water profiles. 31May94 - BP lichen profile frozen below 15 cm; the pond and mire sites had water at the surface, so the entire profiles were water samples. 01Jun94 - OBS lichen profile frozen below 20 cm; OBS lichen profile frozen below 20 cm; OBS collars 13-16 profiles were water samples below 5 cm. 04Jun94 - OBS coast profile frozen below 20 cm; OBS water profile frozen below 25 cm. 08Jun94 - OBS coast profile frozen below 20 cm; OBS moss profile frozen below 25 cm; OBS lichen profile frozen below 25 cm; OBS 13-16 profiles were water samples below 5 cm. 10Jun94 - BP lichen profile frozen below 33 cm; BP moss profile frozen below 25 cm. 16Jun94 - BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 20Jun94 - OBS moss profile frozen below 25 cm; OBS coast profile frozen below 25 cm; OBS collars 1-4 had water below 25 cm; OBS collars 5-8 had water below 25 cm; OBS collars 9-12 had water below 30 cm; OBS collars 13-16 had water throughout the profile. 21Jun94 - BP lichen profile frozen below 30 cm; BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 28Jun94 - OBS collars 9-12 had water below 20 cm; OBS collars 13-16 had water throughout the profile. 30Jun94 - BP collars 25-28 had water below 10 cm; BP collars 29-32 had water below 10 cm. 04Jul94 - OBS collars 9-12 had water below 20 cm; OBS collars 13-16 had water throughout the profile. 08Jul94 - BP collars 21-24 had water below 15 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 13Jul94 - OBS collars 9-12 had water below 25 cm; OBS collars 13-16 had water throughout the profile. 14Jul94 - BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 18Jul94 - BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 20Jul94 - OBS collars 9-12 had water below 25 cm; OBS collars 13-16 had water throughout the profile. 25Jul94 - BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 27Jul94 - OBS collars 9-12 had water below 30 cm; OBS collars 13-16 had water throughout the profile. 01Aug94 - OBS collars 9-12 had water below 30 cm; OBS collars 13-16 had water throughout the profile. 02Aug94 - BP collars 21-24 had water below 10 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 23Aug94 - BP collars 21-24 had water below 20 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 30Aug94 - OBS collars 9-12 had water below 25 cm; OBS collars 13-16 had water below 10 cm. 31Aug94 - BP collars 21-24 had water below 20 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 05Sep94 - BP collars 21-24 had water below 15 cm; BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 06Sep94 - OBS collars 9-12 had water below 25 cm; OBS collars 13-16 had water below 10 cm. 12Sep94 - OBS collars 13-16 had water below 10 cm. 13Sep94 - BP collars 25-28 had water throughout the profile; BP collars 29-32 had water throughout the profile. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage For the data collected with the aluminum chamber fluxes (Patrick Crill): The OJP collars and profile sampling sites were located as follows: Moss collars were approximately northwest of the tower; the profile corral was located a few meters south of the collars (55.9287o N, 98.6248o W). The OJP lichen collars were due west of the tower; the profile trench was located about 1 m southeast of the collars (55.9280o N, 98.62481o W). The YJP collars were located southeast of the tower; the gas profile corral was located approximately 1 m west of the collars (55.9286o N, 98.62019o W). The OBS collars were located along a low to high moisture gradient from the lichen to the feather moss, the fen rim, and ending at the fen site. The lichen and feather moss collars were located along the boardwalk approximately 200 m northeast of the tower. The fen rim and fen site collars were located due east of the lichen and feather moss sites about 150 m and 200 m, respectively. For the soil profile data completed with the plastic chamber fluxes (Dean Moosavi): The OBS collars and profile sampling sites were located as follows: The OBS sampling collars were located along a moisture gradient from feather moss and lichen sites to the fen rim site and ending with the fen sites. The transect ran approximately east to west and was located about 200 m northeast of the tower at the OBS site (55.88007o N, 55.88007o W). The BP collars and profile sampling sites were located as follows: The BP sampling sites were located along a low to high moisture gradient that began with the upland lichen site, then the sphagnum moss site, the mire site and ending at the pond site. The transect runs approximately north to south and is about 60 m from the BP tower (55.8422o N, 98.02747o W). Global Positioning System (GPS) measurements were taken at the sampling sites but the data were not retrievable. 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution Four collars were placed in the ground for each biome type. They were approximately 1 to 2 m apart depending on the site specifics. The collar_type in Section 7.3.3 refers to the dominant vegetation in the collars. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Data were collected from 16-May to 20-Sep-1994. 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution The soil profiles were taken approximately every 7 days beginning 16-May-1994 and ending 13-Sep-1994. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tgb1ccsd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (tgb1ccsd.def). 8. Data Organization 8.1 Data Granularity All of the Soil CH4 and CO2 Profile Data from NSA Tower Sites are contained in one dataset. 8.2 Data Format(s) The data files contain numerical and character fields of varying length separated by commas. The character fields are enclosed with a single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition files (tgb1ccsd.def). 9. Data Manipulations 9.1 Formulae Rf = Cstd / Astd Cs = Rf * As Rf = Response factor Astd = Average of 10 standard peak areas Cstd = Concentration of the standard Cs = Concentration of the sample As = Peak area of sample CH4 and CO2 concentrations were calculated from the average of 10 peak areas of known CH4 and CO2 standards. The response factor was calculated as the concentration of the known standard divided by the average of 10 standard peak areas. The peak area of the unknown sample was multiplied by the response factor. 9.1.1 Derivation Techniques and Algorithms Not applicable. 9.2 Data Processing Sequence 9.2.1 Processing Steps The peak areas were taken directly from the HP ChemStation reports from the GC. They were entered into spreadsheets, and the concentrations were calculated using the formulas in Section 9.1.1. 9.2.2 Processing Changes Not applicable. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None given. 9.3.2 Calculated Variables Not applicable. 9.4 Graphs and Plots None given. 10. Errors 10.1 Sources of Error Sampling error when pulling the syringe samples could include: 1. Sampling too rapidly, causing the air/water sample to be taken from the vertical direction rather than from the depth at which the sampler was located. 2. Not flushing the line before sampling , which could cause dilution of the sample with air/water from the last sampling time. 3. Not completely closing the syringes or allowing them to come open during transport, causing dilution from ambient air. (Errors such as this would have been written down in the lab/field books, and those data therefore would have been edited out.) The analytical precision of the GC's is: 0.2% for CH4 and 1% for CO2. 10.2 Quality Assessment 10.2.1 Data Validation by Source None given. 10.2.2 Confidence Level/Accuracy Judgment None given. 10.2.3 Measurement Error for Parameters The analytical precision of the GC's is: 0.2% for CH4 and 1% for CO2. 10.2.4 Additional Quality Assessments None given. 10.2.5 Data Verification by Data Center Data were examined for general consistency and clarity. 11. Notes 11.1 Limitations of the Data The analytical precision of the GC's is: 0.2% for CH4 and 1% for CO2. 11.2 Known Problems with the Data None overall; see notes under Section 6 and Section 10. 11.3 Usage Guidance None given. 11.4 Other Relevant Information None given. 12. Application of the Data Set This data set may be used in comparison with the chamber flux data to determine the controls on fluxes from these various environments. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description HP ChemStation. 14.2 Software Access Contact Hewlett Packard. 15. Data Access 15.1 Contact Information Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) beth@ltpmail.gsfc.nasa.gov 15.2 Data Center Identification See Section 15.1. 15.3 Procedures for Obtaining Data Users may place requests by telephone, electronic mail, or fax. 15.4 Data Center Status/Plans These data are available from the Earth Observing System Data and Information System (EOSDIS), Oak Ridge National Laboratory (ORNL), Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products None . 16.2 Film Products None. 16.3 Other Products Tabular American Standard Code for Information Interchange (ASCII) file. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Instruction Manual: GC-14A. Shimadzu Corporation, Kyoto, Japan. 17.2 Journal Articles and Study Reports Crill, P.M. 1991. Seasonal patterns of methane uptake and carbon dioxide release by a temperate woodland, Global Biogeochemical Cycles, 5 (4), 319-334. McAuliffe, C.C. 1971. Gas chromatographic determination of solutes by multiple phase equilibration, Chem. Technol., 1, 46-51. Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P. and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue (1997). Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. 17.3 Archive/DBMS Usage Documentation None given. 18. Glossary of Terms None given. 19. List of Acronyms AES - Atmospheric Environment Services ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BP - Beaver Pond CMDL - Climate Monitoring and Diagnostics Laboratory CGR - Certified by Group CPI - Checked by PI CPI-??? - CPI but questionable DAAC - Distributed Active Archive Center ECD - Electron Capture Detector EOS - Earth Observing System EOSDIS - EOS Data and Information System FID - Flame Ionization Detector GC - Gas Chromatograph GSFC - Goddard Space Flight Center GPS - Global Positioning System HP - Hewlett Packard NASA - National Aeronautics and Space Administration NOAA - National Oceanic and Atmospheric Administration NSA - Northern Study Area OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PRE - Preliminary SSA - Southern Study Area TCD - Thermal Conductivity Detector TGB - Trace Gas Biogeochemistry URL - Uniform Resource Locator YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: Last Updated: 20-Jul-1998. 20.2 Document Review Date(s) BORIS Review: 6-Oct-1997 Science Review: 20.3 Document ID 20.4 Citation 20.5 Document Curator 20.6 Document URL Keywords CH4 Concentration CO2 Concentration Soil Profile TGB01_CO2_CH4_Soilprof.doc Page 4 of 14 05/26/98