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Investigation:

TG-07 (Keller / Oliveira)

LBA Dataset ID:

LBA_TG07_TGF

Originator(s):

1. KELLER, M.M.
2. VARNER, R.K.
3. DIAS, J.D.
4. SILVA, H.S.
      5. CRILL, P.M.
6. DE OLIVEIRA, R.C. JR.
7. ASNER, G.P.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

Trace gas fluxes of carbon dioxide, methane, nitrous oxide, and nitric oxide were measured manually at undisturbed and logged forest sites in the Tapajos National Forest, near Santarem, Para, Brazil. Manual measurements were made approximately weekly at both the undisturbed and logged sites. Fluxes from clay and sand soils were completed at the undisturbed sites. Fluxes were measured at the deck (patio), skid trail, clearing and forest at the logged sites. Soil moisture is reported as daily average water-filled pore space (WFPS) for the undisturbed forest clay and sand soils. Data are reported in three ASCII comma separated files.

Beginning Date:

2000-01-19

Ending Date:

2002-02-26

Metadata Last Updated on:

2009-04-30

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=926

Documentation/Other Supporting Documents:

LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002:  http://daac.ornl.gov/LBA/guides/TG07_Soil-Atmosphere_Flux_km83.html

Citation Information - Other Details:

Keller, M.M., R.K. Varner, J.D. Dias, H.S. Silva, P.M. Crill, R.C. de Oliveira, Jr., and G.P. Asner. 2009. LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/926

Keywords - Theme:

Parameter Topic Term Source Sensor
AIR TEMPERATURE ATMOSPHERE ATMOSPHERIC TEMPERATURE FIELD INVESTIGATION THERMOMETER
CARBON DIOXIDE LAND SURFACE SOILS FIELD INVESTIGATION IRGA (INFRARED GAS ANALYZER)
METHANE LAND SURFACE SOILS LABORATORY GC-FID (GAS CHROMATOGRAPH/FLAME IONIZATION DETECTOR)
NITRIC OXIDE LAND SURFACE SOILS FIELD INVESTIGATION CHEMILUMINESCENCE
NITROUS OXIDE LAND SURFACE SOILS LABORATORY GC-ECD (GAS CHROMATOGRAPH/ELECTRON CAPTURE DETECTOR)
SOIL MOISTURE/WATER CONTENT LAND SURFACE SOILS LABORATORY WEIGHING BALANCE
SOIL MOISTURE/WATER CONTENT LAND SURFACE SOILS FIELD INVESTIGATION WEIGHING BALANCE
SOIL TEMPERATURE LAND SURFACE SOILS FIELD INVESTIGATION TEMPERATURE PROBE

Uncontrolled Theme Keyword(s):  CARBON DIOXIDE, METHANE, NITRIC OXIDE, NITROUS OXIDE, SOIL, SOIL MOISTURE, TRACE GAS EXCHANGE

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
Pará Western (Santarém) km 83 Logged Forest Tower Site -3.01700 -3.01700 -54.97070 -54.97070

Related Publication(s):

Keller, M., R. Varner, J.D. Dias, H. Silva, P. Crill, R.C. de Oliveira, Jr., and G.P. Asner. 2005. Soil-Atmosphere Exchange of Nitrous Oxide, Nitric Oxide, Methane, and Carbon Dioxide in Logged and Undisturbed Forest in the Tapajos National Forest, Brazil. Earth Interactions 9(23):1-28.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Manual trace gas exchange measurements of soil-atmosphere fluxes of nitrous oxide (N2O), nitric oxide (NO), methane (CH4), and carbon dioxide (CO2) are reported for both undisturbed forest sites and logged sites. Soil moisture, as daily average water-filled pore space (WFPS),are reported for the undisturbed forest sites only. The files are in ASCII text comma separated format and missing values are represented as -9999.

File name: N2O_and_CH4_flux_Km83.csv

Columns Description

1 Date MM/DD/YYYY

2 Air_T Air temperature in degrees Celsius

3 Soil_T Soil temperature in degrees Celsius

4 Deck deck number at logging site

5 Type site type: for logging sites: deck, clearing, trail and forest; for undisturbed: clay and sand soils

6 Chamber generally 8 chamber measurements per site and treatment

7 N2O_Flux ng-N cm-2 hr-1

8 CH4_Flux mg CH4 m-2 d-1



Example Data Records:



Header records omitted

...



Date,Air_T,Soil_T,Deck,Type,Chamber,N2O_Flux,CH4_Flux

2000/01/19,21.8,23.4,-9999,Deck,1,2.46,-4.469

2000/01/19,21.7,23.5,-9999,Deck,2,1.28,-1.907

2000/01/19,21.7,23.2,-9999,Deck,3,2.222,-2.246



File name: NO_flux and_CO2_flux_Km83.csv

Columns Description

Date YYYY/MM/DD

Type for logging sites: deck, clearing, trail and forest; for undisturbed: clay and sand soils

Deck deck number at logging site

Chamber generally 8 chamber measurements per site and treatment

Air_T degrees Celsius

Soil_T degrees Celsius

NO_Flux ng-N cm-2 hr-1

CO2_Flux umoles CO2 m-2 s-1



Example Data Records:



Header records omitted

...



Date,type,Deck#,Chamber,Air_T,Soil_T,NO_Flux,CO2_flux

2000/09/19,deck,D7,1,30.5,30.8,5.74,1.88

2000/09/19,deck,D7,2,28.9,31.3,7.64,6.99

2000/09/19,deck,D7,3,28.2,30.1,2.38,8.5



File name: Soil_moisture_Km83.csv

Columns Description

Date YYYY/MM/DD

Type for undisturbed: clay and sand soils

WFPS percent water filled pore space

WFPS_STD_err standard error of eight measurements of water-filled pore space

Example Data Records:



Header records omitted

..



Date,Type,WFPS,WFPS_STD_err

2000/02/04,Clay,50.5,1.4

2000/02/18,Clay,51.3,1.3

2000/02/25,Clay,51.5,1.3

...

2001/11/20,Sand,22.5,1.7

2001/12/19,Sand,9.7,0.9

2002/02/06,Sand,38.8,1.7

Data Application and Derivation:

In order to quantify the effect of logging on trace gas fluxes, an excess flux was calculated by subtracting a forest background flux value from the flux for a logged site. Data from the forest matrix within the logging sites or the undisturbed forest were used for background fluxes. The forest matrix values generally were statistically indistinguishable from the nearby undisturbed forest sites.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

The quality of trace gas flux measurements has been discussed. Recently, the question of pressure differentials in chambers has been discussed. We did not directly measure pressure differentials that could exist in our chamber system although according to the source of our dynamic chamber design, the pressure differential between the chamber and the outside air was less than 0.004 Pa in laboratory tests.



For NO measurements, frequent standardization in the field was necessary. The NO2 chemiluminescent analyzer (Scintrex LMA-3) is relatively unstable under the changing temperature, humidity, and background contaminant levels found in the field. Intra-day variation in standards could be as great as 60% even after accounting for linear drift between the beginning and the end of a measurement day. We also compared the concentration of the field NO standard periodically with laboratory standards to assure that they did not drift.

Process Description:

Data Acquisition Materials and Methods:

Field sampling of soil gas flux





Undisturbed forest sites were sampled on 31 dates from 4 February 2000 through 26 February 2002. Measurements of soil-atmosphere flux for N2O and CH4 as well as soil water-filled pore space (WFPS) covered this full period, while measurements of fluxes of NO and CO2 commenced on 10 October 2000 and continued through the end of the study period. The Oxisol and Ultisol sites were sampled on the same day, generally between 0800 and 1800 local time. When all systems were operational, fluxes for all four gases were measured from eight chambers at randomly selected points along 30-m transects. After gas flux sampling was completed, soil samples were removed from each gas sampling location for determination of soil moisture content.





For the logging sites, in 2000, we randomly selected a focal site that we sampled approximately monthly. At that site, we measured fluxes in four sampling strata: the focal deck, adjacent skid trails, gaps, and background forest matrix areas. We defined the forest matrix as those areas more than 10 m distant from decks, skid trails, and gaps. Skid trail measurements were alternated between primary and secondary skid trails. On other dates, we made measurements at other randomly selected sites. In the first half (wet season) of 2000, these additional measurements were purposely biased toward decks and skid trails. On each sampling date, flux chamber locations within each stratum were randomly selected along 30-m transects in a manner similar to their selection within the undisturbed forest. For skid trails, transects were aligned diagonally across the trails in order to cross the tire ruts and the raised area between the ruts. We sampled gas fluxes using enclosures consisting of a section of polyvinylchloride pipe (0.25-m diameter) that served as a base and an acrylonitrile-butadiene-styrene cap that fit snugly on the base. The combination of base plus cap was nearly cylindrical with a height of about 20 cm when inserted into the soil. Bases were inserted at most 30 min prior to flux measurements and they were removed immediately after completion of flux measurements in order to avoid artifacts related to root mortality from chamber insertion. Dynamic open chambers were used for measurement of NO and CO2, and static vented chambers were used for measurements of N2O and CH4. The measurement of these two pairs of gases was sequential, in a haphazard order, after lifting the chamber top to equilibrate the head space with ambient air.





Field analytical system for NO and CO2





We used an integrated flow system to measure NO and CO2. The chamber flow rate was regulated to about 300 cm3 min-1. Air entered the chamber through a chimney-like air gap that was specifically designed to minimize exchange with the outside air and to avoid pressure fluctuations within the chamber. Using this design, the pressure differential between the chamber and the outside air was less than 0.004 Pa in laboratory tests. The chamber base was capped for 3 to 10 min. Air flowed from the soil enclosure through a Teflon-lined polyethylene sample line 30 m in length and then it entered an infrared gas analyzer (Li-Cor 6262) for CO2 measurement. From the Li-6262, the sampled air then passed through a flow control manifold where it was mixed with a makeup airflow of about 1200 cm3 min-1 and a flow of NO (1 ppm) in oxygen-free nitrogen standard gas that varied from 3 to 10 cm3 min-1 as measured on an electronic mass flowmeter (Sierra Top-Trak). The flowmeter was checked occasionally against a NIST-traceable electronic bubble flowmeter (Gilibrator). The makeup air and standard additions maintained optimum and linear performance of the NO2 chemiluminescent analyzer (Scintrex LMA-3) according to the manufacturer\'s recommendations. The mixed sample stream passed through a Cr2O3 catalyst for conversion of NO to NO2. The NO2 chemiluminescent analyzer was standardized by a two-point calibration approximately hourly. Frequent standardization in the field was necessary because the LMA-3 was relatively unstable under the changing temperature, humidity, and background contaminant levels found in the field. Intraday variation in standards could be as great as 60% even after accounting for linear drift between the beginning and the end of a measurement day. We also compared the concentration of the field NO standard periodically with laboratory standards to assure that they did not drift. Signals from the CO2 and NO2 analyzers and the mass flowmeter for the NO standard gas were recorded on a datalogger (Campbell CR10). Fluxes were calculated from the linear increase of concentration versus time adjusted for the ratio of chamber volume to area and the air density within the chamber.





Analysis of CH4 and N2O





We made static enclosure measurements for CH4 and N2O fluxes using the same bases and vented caps. Four enclosure headspace samples were taken over a 30-min sampling period with 20-mL nylon syringes. Analysis of grab samples for CH4 and N2O were completed within 36 h by FID and ECD gas chromatography. Gas concentrations were calculated by comparing peak areas for samples to those for commercially prepared standards (Scott-Marin) that had been calibrated against the LBA-ECO (a component of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia) standards prepared by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostic Laboratory (NOAA/CMDL). Fluxes were calculated similarly to those for CO2 and NO.





Determination of soil WFPS





Soil samples were taken to 10-cm depth in each chamber location on each date for determination of soil moisture (oven dried at 105C). Soil moisture was expressed as WFPS using soil bulk densities of 1.25 and 1.02 for Ultisol and Oxisol soils, respectively, at the undisturbed forest sites. Bulk densities for the logged sites were measured as described below. We recorded air and soil (2-cm depth) temperature using thermistor probes to accompany each soil enclosure measurement. Precipitation was measured daily using a manual rain gauge in an open field approximately 3-7 km from the various study areas.

References:

Keller, M., and W. A. Reiners (1994), Soil-atmosphere exchange of nitrous oxide, nitric oxide, and methane under secondary succession of pasture to forest in the Atlantic lowlands of Costa Rica. Global Biogeochem. Cycles, 8, 399-410. doi:10.1029/94GB01660



Keller, M., A. M. Weitz, B. Bryan, M. M. Rivera, and W. L. Silver (2000), Soil-atmosphere nitrogen oxide fluxes: Effects of root disturbance. J. Geophys. Res., 105, 17 693-698.



Keller, M., R. K. Varner, J. D. Dias, H. Silva, P. Crill, R. C. de Oliveira, Jr. and G. P. Asner (2005), Soil-Atmosphere Exchange of Nitrous Oxide, Nitric Oxide, Methane, and Carbon Dioxide in Logged and Undisturbed Forest in the Tapajos National Forest, Brazil. Earth Interactions 9(23):1-28. doi:10.1175/EI125.1



Levaggi, D., E. L. Kothny, T. Belsky, E. de Vera, and P. K. Mueller (1974), Quantitative analysis of nitric oxide in the presence of nitrogen dioxide at atmospheric concentrations. Environ. Sci. Technol., 8, 348-350. doi:10.1021/es60089a003





Rayment, M. B., and P. G. Jarvis (1997), An improved open chamber system for measuring soil CO2 effluxes in the field. J. Geophys. Res., 102, 28 779-784.



Silver, W. L., J. Neff, M. McGroddy, E. Veldkamp, M. Keller, and R. Cosme, (2000), Effects of soil texture on belowground carbon and nutrient storage in a lowland Amazonian forest ecosystem. Ecosystems, 3, 193-209. doi:10.1007/s100210000019



Varner, R. K., M. Keller, J. R. Robertson, J. D. Dias, H. Silva, P. M. Crill, M. McGroddy, and W. L. Silver (2003), Experimentally induced root mortality increased nitrous oxide emissions from tropical forest soils. Geophys. Res. Lett., 30, 1144, doi:10.1029/2002GL016164.



Veldkamp E. and M. Keller (2007), Nitrogen oxide emissions from a banana plantation in the humid tropics. Journal of Geophysical Research-Atmospheres 102 (D13): 15889-15898 JUL 20 1997.



Xu, L., M. D. Furtaw, R. A. Madsen, R. L. Garcia, D. L. Anderson and D. K. McDermitt (2006), On maintaining pressure equilibrium between a soil CO2 flux chamber and the ambient air, J. Geophy. Res., 111, D08S10; doi:10.1029/2005JD006435.

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