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Investigation:

CD-08 (Trumbore / Camargo)

LBA Dataset ID:

CD08_ISOTOPES_BELOWGROUND

Originator(s):

1. TELLES, E.D.C.
2. DE CAMARGO, P.B.
3. MARTINELLI, L.A.
4. TRUMBORE, S.E.
5. DA COSTA, E.S.
      6. SANTOS, J.
7. HIGUCHI, N.
8. OLIVEIRA, R.C.D.
9. MARKEWITZ, D.

Point(s) of Contact:

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

Dataset Abstract:

This data set contains carbon isotope signatures from soil organic matter collected from the following sites: the forests of the ZF-2 INPA reserve approximately 80 km north of the city of Manaus, Amazon; the Tapajos National Forest approximately 83 km south of the city of Santarem, Para; and the Fazenda Vitoria, a ranch near the city of Paragominas, Para. Samples from the Fazenda Vitoria were from degraded and managed pasture sites as well as mature and secondary forests. In addition,carbon isotope signatures from roots sorted by size class, hand-picked from soil pits in the Flona Tapajos and Fazenda Vitoria, are included, as are carbon isotope signatures from soil gases from samples collected at the Fazenda Vitoria. There are 4 ASCII data files with this data set.

Beginning Date:

1992-05-01

Ending Date:

1999-07-05

Metadata Last Updated on:

2011-08-22

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 CD-08 Carbon Isotopes in Belowground Carbon Pools, Amazonas and Para, Brazil :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1025

Documentation/Other Supporting Documents:

LBA-ECO CD-08 Carbon Isotopes in Belowground Carbon Pools, Amazonas and Para, Brazil :  http://daac.ornl.gov/LBA/guides/CD08_C_Isotopes_Belowground.html

Citation Information - Other Details:

Telles E.D.C., P.B. de Camargo, L.A. Martinelli, S.E. Trumbore, E.S. da Costa, J. Santos, N. Higuchi, R.C. Oliveira and D. Markewitz. 2011. LBA-ECO CD-08 Carbon Isotopes in Belowground Carbon Pools, Amazonas and Para, Brazil. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1025

Keywords - Theme:

Parameter Topic Term Source Sensor
CARBON LAND SURFACE SOILS LABORATORY MASS SPECTROMETER
CARBON LAND SURFACE SOILS LABORATORY CHN ANALYZER
ISOTOPES LAND SURFACE SOILS LABORATORY MASS SPECTROMETER
SOIL GAS/AIR LAND SURFACE SOILS LABORATORY MASS SPECTROMETER

Uncontrolled Theme Keyword(s):  C13, C14, CARBON ISOTOPES, CARBON13, RADIOCARBON, ROOTS, SOIL CARBON, SOIL ORGANIC MATTER

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  PARA EASTERN (BELEM) AMAZONAS (MANAUS) PARA WESTERN (SANTAREM) -2.50000 -3.01700 -47.51600 -60.20910

Related Publication(s):

Brando, P.M., D.C. Nepstad, E.A. Davidson, S.E. Trumbore, D. Ray, and P. Camargo. 2008. Drought effects on litterfall, wood production and belowground carbon cycling in an Amazon forest: results of a throughfall reduction experiment. Philosophical Transactions of the Royal Society B-Biological Sciences 363(1498):1839-1848.

Davidson, E.A. and S.E. Trumbore. 1995. Gas diffusivity and production of CO2 in deep soils of the eastern Amazon, Tellus Series B-Chemical and Physical Meteorology 47B(5): 550-565.

de Camargo, P.B., S.E. Trumbore, L.A. Martinelli, E.A. Davidson, D.C. Nepstad, and R.L. Victoria. (1999) Soil carbon dynamics in regrowing forest of eastern Amazonia. Global Change Biology 5(6):693-702

Telles, E.D.C., P.B. de Camargo, L.A. Martinelli, S.E. Trumbore, E.S. da Costa, J. Santos, N. Higuchi, and R.C. Oliveira. 2003. Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia. Global Biogeochemical Cycles 17(2):1040, 2003 May 2.

Trumbore, S., E.S. da Costa, D.C. Nepstad, P.B. de Camargo, L.I.Z.A. Martinelli, D. Ray, T. Restom, and W. Silver. 2006. Dynamics of fine root carbon in Amazonian tropical ecosystems and the contribution of roots to soil respiration. Global Change Biology 12(2):217-229.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are presented in four ASCII comma-delimited (.csv) files:

File 1: C_isotopes_roots_and_SOM_Tapajos_and_Manaus.csv

File 2: C_isotopes_SOM_Paragominas_1996.csv

File 3: C_isotopes_roots_Paragominas.csv

File 4: C_isotopes_soil_CO2_Paragominas.csv



File #1: C_isotopes_roots_and_SOM_Tapajos_and_Manaus.csv

Column Heading Units/format Description

1 Site Sampling site: Santarem_Flona_Tapajos_km83 or Manaus_ZF2_transect

2 Year_collected yyyy Sampling date: year collected (yyyy)

3 Ecosystem_type Ecosystem type: mature forest

4 Sampling_area Specific sampling location

5 Depth cm Sampling depth in centimeters (cm)

6 UCI_Lab_number Sample ID for analysis

7 C_conc % Carbon concentration in sample reported in percent (%)

8 delta_13C per mil delta (lowercase greek delta) 13C data are reported as [[13C/12C ratio of the sample divided by the 13C/12C of the PeeDee Belemnite standard] -1]*1000, or the deviation in parts per thousand of the 13C/12C ratio of the standard from the 13C/12C of the PDB standard. Measured using the Fisons elemental analyzer as the input to a continuous flow stable isotope ratio mass spectrometer

9 Delta_14C per mil Measured delta 14C. Delta (capital greek Delta) 14C data are reported as [[14C/12C ratio of the sample divided by 0.95 times the 14C/12C of the Oxalic Acid I standard, decay corrected to 1950] -1]*1000. A mass dependent 13C correction has been applied so that the reported 14C value is for a delta 13C of -25 per mil, and the Oxalic Acid I standard has a 13C value of -19 per mil. The decay corrections corrects for changes in the 14C content of the Oxalic Acid I standard between the year of measurement (assumed the same as the year of sampling) and 1950. For more information see Stuiver and Polach (1977)

10 Error_D14C per mil Error associated with the Delta 14C measurement [Delta_14C]



Reference: Stuiver, M., Polach, H.A., 1977. Reporting of C-14 data-Discussion. Radiocarbon 19, 355-363 Missing data are represented by -9999



Example data records



Site,Year_collected,Ecosystem_type,Sampling_area,Depth,Material,UCI_Lab_number,C_conc,delta_13C,Delta_14C,Error_D14C



Santarem_Flona_Tapajos_km83,1999,mature forest,Telles_Site_MB,5,bulk_soil,UCIT6098,0.7,-28.36,114.45,4.52

Santarem_Flona_Tapajos_km83,1999,mature forest,Telles_Site_MB,10,bulk_soil,UCIT6099,1,-27.44,21.55,3.79

Santarem_Flona_Tapajos_km83,1999,mature forest,Telles_Site_MB,20,bulk_soil,UCIT6100,1,-26.97,-17.59,4.51

...

Manaus_ZF2_transect,1999,mature forest,Telles_Site_MB,5,bulk_soil,UCIT6082,2.1,-29.72,131.27,4.99

Manaus_ZF2_transect,1999,mature forest,Telles_Site_MB,10,bulk_soil,UCIT6083,1.2,-29.65,143.43,4.04

Manaus_ZF2_transect,1999,mature forest,Telles_Site_MB,20,bulk_soil,UCIT6084,0.5,-29.63,135.89,5.01

...



File #2: C_isotopes_SOM_Paragominas_1996.csv



Column Heading Units/format Description

1 Year_collected YYYY Sampling date: year collected (yyyy)

2 Site Sampling site identification code: Fazenda_Victoria_Paragominas_PA

3 Ecosystem_type Ecosystem type: mature forest, secondary forest, managed pasture or degraded pasture

4 Depth cm Sampling depth in centimeters (cm)

5 Heavy_fraction percent Percent of total soil C found in the fraction having a density greater than 2.1 g per cc

6 Light_fraction percent Percent of total soil C found in the fraction having a density less than 2.1 g per cc

7 Residue_fraction percent Percent of total soil C found in the material remaining after the extraction of the heavy fraction with acid and base hydrolysis

8 Hydrolyzate_fraction percent Percent of total soil C found in the fraction removed by acid and base hydrolysis calculated by difference not measured directly

9 Bulk_soil_C_fine percent Percent of total soil C pool found in the particles having a diameter less than 2 microns

10 C_conc_heavy percent Carbon concentration in the heavy fraction measured in percent by weight (%)

11 N_conc_heavy percent Mass based C to N ratio in the heavy fraction

12 CN_heavy Mass based C to N ratio in the heavy fraction

13 Delta_14C_heavy per mil Measured delta 14C. Delta (capital greek Delta) 14C data are reported as [[14C/12C ratio of the sample divided by 0.95 times the 14C/12C of the Oxalic Acid I standard, decay corrected to 1950] -1]*1000. A mass dependent 13C correction has been applied so that the reported 14C value is for a delta 13C of -25 per mil, and the Oxalic Acid I standard has a 13C value of -19 per mil. The decay corrections corrects for changes in the 14C content of the Oxalic Acid I standard between the year of measurement (assumed the same as the year of sampling) and 1950). For more information see Stuiver and Polach (1977)

14 delta_13C_heavy per mil delta 13C of the heavy fraction reported in parts per mil. delta (lowercase greek delta) 13C data are reported as [[13C/12C ratio of the sample divided by the 13C/12C of the PeeDee Belemnite standard] -1]*1000, or the deviation in parts per thousand of the 13C/12C ratio of the standard from the 13C/12C of the PDB standard. Measured using the Fisons elemental analyzer as the input to a continuous flow stable isotope ratio mass spectrometer

15 C_conc_hydrolyzate percent Carbon concentration in the hydrolyzate

16 Delta_14C_hydrolyzate per mil Delta (uppercase greek delta) 14C of the C found in the hydrolyzate, reported in parts per mil. For a complete description of Delta 14C measurements see above

17 delta_13C_hydrolyzate per mil delta (lowercase greek delta) 13C of the C found in the hydrolyzate reported in parts per mil. For a complete description of delta 13C measurements see above

18 Residue_C_conc percent Carbon concentration in the residue

19 Residue_N_conc percent Nitrogen concentration in the residue

20 CN_residue Mass based C to N ratio in the residue

21 Delta_14C_residue per mil Delta (uppercase greek delta) 14C of the C found in the residue reported in parts per mil. For a complete description of Delta 14C measurements see above

22 delta_13C_residue per mil delta (lowercase greek delta) 13C of the C found in the residue reported in parts per mil. For a complete description of delta 13C measurements see above

23 Light_fraction_C_conc percent Concentration of carbon in the light fraction of the soil reported in percent (%)

24 Light_fraction_N_conc percent Concentration of nitrogen in the light fraction of the soil reported in percent (%)

25 CN_light Mass based C to N ratio in the light fraction

26 Delta_14C_light per mil Delta (uppercase greek delta) 14C of the C found in the light fraction reported in parts per mil. For a complete description of Delta 14C measurements see above

27 delta_13C_light per mil delta (lowercase greek delta) 13C of the C found in the light fraction reported in parts per mil. For a complete description of delta 13C measurements see above

28 Delta_14C_roots per mil Delta (uppercase greek delta) 14C of the C found in the root biomass from this depth reported in parts per mil. For a complete description of Delta 14C measurements see above

29 delta_13C_roots per mil delta (lowercase greek delta) 13C of the C found in the root biomass at this depth reported in parts per mil. For a complete description of delta 13C measurements see above

30 Delta_14C_charcoal per mil Delta (uppercase greek delta) 14C of the C found in the charcoal fragments picked from this depth interval reported in parts per mil. For a complete description of Delta 14C measurements see above

31 delta_13C_charcoal per mil delta (lowercase greek delta) 13C of the C found in the charcoal fragments picked from this depth interval, reported in parts per mil. For a complete description of Delta 13C measurements see above



Reference: Stuiver, M., Polach, H.A., 1977. Reporting of C-14 data-Discussion. Radiocarbon 19, 355-363

Missing data are represented by -9999





Example data records



Year_collected,Site,Ecosystem_type,Depth_cm,Heavy_fraction,Light_fraction,Residue_fraction,Hydrolyzate_fraction,

Bulk_soil_C_fine, C_conc_heavy,N_conc_heavy,CN_heavy,Delta_14C_heavy,delta_13C_heavy,C_conc_hydrolyzate,

Delta_14C_hydrolyzate,delta_13C_hydrolyzate,Residue_C_conc,Residue_N_conc,CN_residue,Delta_14C_residue,delta_13C_residue,

Light_fraction_C_conc,Light_fraction_N_conc,CN_light,Delta_14C_light,delta_13C_light,Delta_14C_roots,delta_13C_roots,

Delta_14C_charcoal,delta_13C_charcoal



1996,Fazenda_Victoria_Paragominas_PA,mature forest,0,63.3,36.7,20.4,42.9,

2.46,2.11,0.18,11.45,113.23,-26.91,2.7,

159.8,-26, 0.91,0.05,17.11,15.23,

-28.78,29.79,1.5,19.86,160.37,-28.25,143.67,-27.28,

-9999,-9999

1996,Fazenda_Victoria_Paragominas_PA,mature forest,10,60,40,15.4,

44.6,1.46,1.2,0.11,11.06,1,-26.19,

1.5,67.3,-25.6,0.42,0.02,17.5,-190.47,

-27.99,-9999,-9999,-9999,-9999,-9999,-9999,-9999,

-9999,-9999

...

1996,Fazenda_Victoria_Paragominas_PA,degraded pasture,0,44.9,55.1,14.4,

30.5,2.9,1.93,0.17,11.43,153.94,-25.26,

2.4,218.6,-24.1,0.89,0.04,22.25,16.71,

-27.76,26.19,1.44,18.25,147.54,-26.95,128.24,-22.16,

157.71,-28.3

1996,Fazenda_Victoria_Paragominas_PA,degraded pasture,10,55.1,44.9,15.3,

39.7,1.38, 1.08,0.09,11.9,-40.75,-25.49,

1.3,27.9,-24.7,0.43,0.03,13.87,-218.62,

-27.47,-9999,-9999,-9999,-9999,-9999,-9999,-9999,

-9999,-9999

...





File #3: C_isotopes_roots_Paragominas.csv



Column Heading Units/format Description

1 Site Sampling site: Paragominas

2 Year_mm_collected yyyy/mm Sampling date: year and month collected (yyyy/mm)

3 Ecosystem_type Ecosystem type: mature forest, secondary forest, managed pasture, reformed pasture, or degraded pasture

4 Depth cm Sampling depth in centimeters (cm) from the soil surface

5 Live_dead Root status determined by texture and color analysis

6 Root_diameter mm Root classification based on diameter

7 Root_diameter mm Root classification based on diameter

8 UCI_number S ample id number

9 delta_13C_assumed per mil Delta 13C value assigned to the sample based on published data for similar samples; these values were used only for correcting the Delta 14C data and were not measured directly on samples

10 Delta_14C per mil Measured delta 14C of the root tissue. Delta (capital greek Delta) 14C data are reported as [[14C/12C ratio of the sample divided by 0.95 times the 14C/12C of the Oxalic Acid I standard, decay corrected to 1950] -1]*1000. A mass dependent 13C correction has been applied so that the reported 14C value is for a delta 13C of -25 per mil, and the Oxalic Acid I standard has a 13C value of -19 per mil. The decay corrections corrects for changes in the 14C content of the Oxalic Acid I standard between the year of measurement (assumed the same as the year of sampling) and 1950 . For more information see Stuiver and Polach (1977)

11 Delta_14_atmosphere per mil Delta 14C of the atmosphere at the sampling date

12 Delta_Delta_14C per mil Calculated difference between atmospheric and root tissue Delta 14C



Reference: Stuiver, M., Polach, H.A., 1977. Reporting of C-14 data-Discussion. Radiocarbon 19, 355-363

Missing data are represented by -9999



Example data records



Site,Year_mm_collected,Ecosystem_type,Depth,Live_dead,Root_diameter,UCI_number,delta_13C_measured,

delta_13C_assumed,Delta_14C,Delta_14_atmosphere,Delta_Delta_14C



Paragominas,1993/02,mature forest,40-60,dead,less than 1 mm,UCIT1276,-9999,

-28,198.2,131.8,66.4

Paragominas,1993/02,mature forest,135-165 ,dead,less than 1 mm,UCIT1277,-9999,

-28,231.6,131.8,99.8

Paragominas,1993/02,mature forest,285-315,dead,less than 1 mm,UCIT1278,-9999,

-28,177.4,131.8,45.6

...

Paragominas,1993/02,degraded pasture,40-60,dead,less than 1 mm,UCIT1281,-9999,

-18,152.5,131.8,20.7

Paragominas,1993/02,degraded pasture,135-165 ,dead,less than 1 mm,UCIT1282,-9999,

-18,133.2,131.8,1.4

Paragominas,1993/02,degraded pasture,285-315,dead,less than 1 mm,UCIT1283,-9999,

-25,99.9,131.8,-31.9

...

Paragominas,1996/06,managed pasture,50-100,live,less than 0.5 mm,UCIT5760,-12,

-9999,123.7,114.5,9.2

Paragominas,1996/06,managed pasture,50-100,live,0.5-1 mm,UCIT5761,-12,

-9999,123.9,114.5,15.4

Paragominas,1996/06,managed pasture,50-100,live,1-2 mm,UCIT5762,-12,

-9999,173.8,114.5,59.4



File #4: C_isotopes_soil_CO2_Paragominas.csv



Column Heading Units/format Description

1 Year_mm_collected YYYY/MM Sampling date: year and month collected (yyyy/mm)

2 Site Sampling site identification code: P* = Pasture sites; M* = Mature forest sites; Cap* = Secondary forests

3 Ecosystem_type Ecosystem type: mature forest, secondary forest, or pasture

4 Depth cm Sampling depth in centimeters (cm)

5 Delta_14C_CO2 per mil Delta 14C of CO2 collected from the soil depth indicated in per mil. Delta (capital greek Delta) 14C data are reported as [[14C/12C ratio of the sample divided by 0.95 times the 14C/12C of the Oxalic Acid I standard, decay corrected to 1950] -1]*1000. A mass dependent 13C correction has been applied so that the reported 14C value is for a delta 13C of -25 per mil, and the Oxalic Acid I standard has a 13C value of -19 per mil. The decay corrections corrects for changes in the 14C content of the Oxalic Acid I standard between the year of measurement (assumed the same as the year of sampling) and 1950. For more information see Stuiver and Polach (1977)

6 CO2_conc percent CO2 concentration of the sample in percent (%) uncorrected for pit wall diffusion

7 delta_13C_CO2 per mil Measured delta 13C of CO2 collected from the soil depth indicated. delta (lowercase greek delta) 13C data are reported as [[13C/12C ratio of the sample divided by the 13C/12C of the PeeDee Belemnite standard] -1]*1000, or the deviation in parts per thousand of the 13C/12C ratio of the standard from the 13C/12C of the PDB standard

8 delta_13C_SOM per mil delta 13C of soil organic matter collected at the depth indicated. For a complete description of the delta 13 value see above



Reference: Stuiver, M., Polach, H.A., 1977. Reporting of C-14 data-Discussion. Radiocarbon 19, 355-363

Missing data are represented by -9999; missing sites = Not provided





Example data records



Year_mm_collected,Site,Ecosystem_type,Depth ,14C_CO2 ,CO2_conc,13C_CO2,13C_SOM



1992/05,MC,mature forest,0,-9999,-9999,-9999,-27.6

1992/05,MC,mature forest,25,155.1,1.48,-25,-9999

...

1992/11,PE,pasture,25,147.3,0.94,-21.41,-9999

1992/11,PE,pasture,50,-9999,0.87,-9999,-9999

...

1999/05,Cap B,secondary forest,17,121.9,4.9,-25.73,-9999

1999/05,Cap B,secondary forest,25,-9999,-9999,-9999,-9999

...



Data Application and Derivation:

Understanding the dynamics of the soil C pools requires an accurate measurement of the size of the pools and the fluxes in and out of each pool as well as the residence time of C in each. The rate of incorporation of nuclear weapons testing 14C into the soil C reservoir provides a useful tool for deciphering C turnover in soils on timescales of decades to hundreds of years. Using the radiocarbon signature of the current atmosphere and steady state assumptions, the decomposition rate of each C pool can be determined. There are few data on the age of C in the fine root pool in tropical forests. Surface litter inputs into the soil C pools generally reflect the atmospheric radiocarbon signature of the current year, however, for roots the average time elapsed since the material from which it was constructed was fixed from the atmosphere by photosynthesis may vary significantly.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

The data have been reviewed and there are no known problems with them.



Radiocarbon data are reported in delta notation (per mil deviation from 95% of the 14C/12C ratio of oxalic acid I standard, decay corrected to 1950). All samples have been corrected for mass-dependent fractionation of 14C using the 13C data.



The analytical uncertainty associated with these radiocarbon analyses is plus/minus 5 per mil based on repeated determinations of secondary standards. The Delta 14C data were measured in the year of sampling.



The precision of 13C analysis was plus/minus 0.1 per mil.

Process Description:

Data Acquisition Materials and Methods:

Data were collected from the following sites: ZF-2 INPA reserve approximately 80 km north of the city of Manaus, Amazon; the Tapajos National Forest approximately 83 km south of the city of Santarem, Para; and the Fazenda Vitoria, a ranch near the city of Paragominas, Para.



The Manaus site is characterized by kaolinite clay rich Oxisols on the plateaus, and intermittently flooded, sandy textured soils (Spodosols) in the lowland sites along the small streams that dissect the plateau areas. At the Tapajos site there are similar clay rich Oxisol dominated plateaus and sandier (Oxisols) soils in local depressions though these soils are well drained unlike what is found in Manaus.



The Fazenda Vitoria site is a ranch in Paragominas with pasture sites, secondary and mature forests. This site experiences seasonal drought with less than 250 mm of the total annual precipitation of 1,750 mm falling between June and November. Despite the extended dry season, the forests in this region are evergreen. To compare soil carbon cycling in pastures and forests, study plots were set up in 3 mature forest sites, 2 degraded pasture sites and 2 managed pasture sites. The degraded pasture site was originally cleared in 1969, planted with Panicum maximum and later Brachiaria humidicola, and has been heavily grazed to the present. Woody shrubs and treelets now dominate the site and it supports little grazing. The managed pasture shared a similar land use history until 1987 when it was disk-harrowed, fertilized with phosphorus, and reseeded with a more productive C4 grass. It currently has no woody shrubs.



Soil sample collections:

Soil samples were collected from all sites. Sixteen soil profiles in each of the four soil types were sampled to a depth of 50 cm for C stocks. Three pits for each soil were sampled to 2 m depth. Samples from one representative 2 m pit were analyzed for radiocarbon and stable isotopes and these data are presented here. In addition to soil samples, bulk charcoal samples were separated from soil and run for radiocarbon and stable isotopes using the same methodology.



Root sample collections:

Fine root samples were collected in 1999 from deep soil pits in a sandy loam soil at the km 83 site within the Tapajos National Forest (Telles et al., 2003). Roots were not separated into live and dead categories. Soil cores were subsampled for fine roots at 0-10, 40-60, 135-155, 285-305 cm depth intervals, using the same methods by which fine roots were sampled in Paragominas between 1993 and 1996.



Soil sample preparation and analysis:

Soil samples were sieved to less than 2 mm diameter and homogenized. Fine roots and charcoal were removed and the soils were ground for analysis. Gravimetric C content and C stable isotopic composition, expressed as delta 13C, were measured using an elemental analyzer coupled to a continuous flow stable isotope ratio mass spectrometer at the USP CENA campus in Piracicaba, Sao Paulo state. Samples for radiocarbon analysis were sealed in evacuated quartz tubes with cupric oxide wire and combusted at 900 degrees C for 2 hours. Evolved CO2 was purified cryogenically and then reduced to graphite by the zinc reduction method (Vogel 1992) for analysis accelerator mass spectrometry at the Center for AMS at the Lawrence Livermore National Laboratory, Livermore CA or at the WM Keck Carbon Cycle AMS facility at UC Irvine.



Root sample preparation and analysis:

Roots were separated from bulk soil by flotation (Nepstad et al., 1994) and separated into two size fractions (less than 1 mm and between one and 2 mm diameter). For the samples from the clay Oxisol live and dead fine root pools were separated by hand using texture and color criteria to distinguish roots. Separated roots were weighed and then stored in alcohol. Samples for radiocarbon were pretreated following Gaudinski et al. (2001). Fine roots were washed sequentially in 1 N HCl, 1N NaOH and 1N HCl with distilled water rinses after each step. Pretreated samples were then oven dried at 60 degrees C and ground. Ground root tissue was combusted in quartz tubes with cupric oxide wire and combusted at 900 degrees C for 2 hours. Evolved CO2 was purified cryogenically, subsampled for 13C analysis and then reduced to graphite by the zinc reduction method (Vogel 1992) for analysis by accelerated mass spectrometry at the Center for AMS at the Lawrence Livermore National Laboratory, Livermore CA. Stable C isotopes were measured using dual inlet isotope ratio mass spectrometry in the CENA laboratory.



Soil gas sample collection:

Soil gases were collected from stainless steel tubes perforated at one end and installed into the walls of soil pits, as described in Davidson and Trumbore (1995). Tubes were capped with septa and syringes were used to draw ~10 ml samples for concentration measurements. For isotope samples, tubes were either connected to pre-evacuated 500 cc steel canisters (for depths up to 100 cm) or 60 cc syringe samples were used to fill serum vials sealed with butyl rubber septa (for depths >100 cm). Samples were transported to the isotope laboratory at CENA for purification of CO2 and preparation of graphite and AMS measurement as above.

References:

Davidson, E.A. and S.E. Trumbore. 1995. Gas diffusivity and production of CO2 in deep soils of the eastern Amazon, Tellus Series B-Chemical and Physical Meteorology 47B(5): 550-565.



Gaudinski, J.B., S.E. Trumbore, E.A. Davidson, A.C. Cook, S. Markewitz and D.D. Richter. 2001. The age of fine-root carbon in three forest of the eastern United States measured by radiocarbon. Oecologia 129: 420-429



Nepstad, D.C., C.R. Decarvalho, E.A. Davidson et al. 1994. The role of c: 666-669.



Stuiver, M. and Polach, H.A. 1977. Discussion: Reporting of 14C Data. Radiocarbon 19(3), 1977, p. 355â�â�œ363.



Telles, E.D.C., P.B. de Camargo, L.A. Martinelli, S.E. Trumbore, E.S. da Costa, J. Santos, N. Higuchi, and R.C. Oliveira. 2003. Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia. Global Biogeochemical Cycles 17(2):1040, 2003 May 2.



Vogel, J.S. 1992. A rapid method for preparation of biomedical targets for AMS. Radiocarbon 34: 344-350.

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