NOTICE -- The LBA-ECO Project website is no longer being supported.  This archive is a snapshot, as it existed in 2013, of the LBA-ECO website, maintained by NASA Goddard Space Flight Center, and now archived at the ORNL DAAC.  Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC.
banner
banner banner banner banner banner banner
banner banner banner banner banner banner banner
home aboutlibrarynews archivecontacts banner

spacer
banner
Investigations
Overview
Abstracts & Profiles
Publications
Research Sites
Meetings
Synthesis Groups
LBA-HYDROMET
LBA-Air-ECO
Logistics
Overview
Field Support
Travel
Visa
Shipping
Data
  Overview
Find LBA Data
Investigator Checklist
Process & Policy
Documentation & Archive
Training & Education
  Overview
Activities Summary
T&E Goals
Student Opportunities
  Folha Amazônica
 
spacer

Investigation:

TG-09 (Trumbore / Perez / Camargo)

LBA Dataset ID:

LBA_TG09_N2O_SOILS

Originator(s):

PEREZ, T.

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 reports the results of carbon, nitrogen, and oxygen isotopic analyses of soil, soil water, and N2O soil gas samples; total soil carbon and nitrogen concentrations; and soil texture and bulk density. Samples were collected from the km 83 Logged Forest Tower Site and the km 67 Seca-Floresta Site in the Tapajos National Forest (TNF) near Santarem, Para, Brazil. Soil samples were collected in July of 2000 and soil gas samples were collected in 2001 and 2002. Soil and gas samples were collected from various soil types at each site and from several depths in specially constructed pits. There is one comma-delimited ASCII data file with this data set.

Beginning Date:

2000-07-08

Ending Date:

2002-03-23

Metadata Last Updated on:

2011-05-19

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-09 Soil Isotopic C, N, H2O, and N2O Data, Tapajos National Forest, Brazil :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1013

Documentation/Other Supporting Documents:

LBA-ECO TG-09 Soil Isotopic C, N, H2O, and N2O Data, Tapajos National Forest, Brazil :  http://daac.ornl.gov/LBA/guides/TG09_N2O_Soils.html

Citation Information - Other Details:

Perez, T. 2011. LBA-ECO TG-09 Soil Isotopic C, N, H2O, and N2O Data, Tapajos National Forest, 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. doi:10.3334/ORNLDAAC/1013

Keywords - Theme:

Parameter Topic Term Source Sensor
CARBON LAND SURFACE SOILS LABORATORY IRMS (Isotope Ratio Mass Spectrometer)
NITROGEN LAND SURFACE SOILS LABORATORY IRMS (Isotope Ratio Mass Spectrometer)
NITROUS OXIDE ATMOSPHERE SOILS LABORATORY IRMS (Isotope Ratio Mass Spectrometer)
RADIOISOTOPES LAND SURFACE SOILS LABORATORY IRMS (Isotope Ratio Mass Spectrometer)
SOIL BULK DENSITY LAND SURFACE SOILS LABORATORY WEIGHING BALANCE
SOIL TEXTURE LAND SURFACE SOILS LABORATORY ANALYSIS

Uncontrolled Theme Keyword(s):  CN RATIO, DELTA 18O, DELTA_13C, DELTA_15N, NITROGEN CYCLING, NITROUS OXIDE, SOIL EMISSIONS, SOIL GAS, STABLE ISOTOPES

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  PARA WESTERN (SANTAREM) -2.75000 -3.01700 -54.97070 -55.00000

Related Publication(s):

Perez, T. 2005. Factors that Control the Isotopic Composition of N20 from Soil Emissions. In Stable Isotopes and Biosphere-Atmosphere Interactions: Processes and Biological Controls. L.B. Flanagan, J.R. Ehleringer, D.E. Pataki, Eds. A Volume in the Physiological Ecology Series, Elsevier Press. 69-84, 2005.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are presented in one comma separated ASCII file: TG09_Isotopes_in_Soil_Pools_Tapajos.csv

Column Heading Units/format Description
1 ID Sample ID, replicate samples are given the same number and are distinguished by A or B
2 Site Sampling location within the Tapajos National Forest, south of Santarem Para
3 Pit_ID At km 83: C = Clay soil, SC = sand/clay transition soil, S = sand soil. A and B are replicate pits. At the Seca Floresta plots, km 67: CF = control plot, A = pit 1, B= pit 2; SF = dry down plot A=pit 4, B=pit 6)
4 Depth (cm) Sample depth (cm)
5 Collection_date_soils yyyy/mm/dd Collection date (yyyy/mm/dd) for soil samples (data in columns 6-14)
6 Bulk_density g cm-3 Dry weight of soil per unit volume reported as grams per cubic centimeter (g cm-3)
7 delta_13C_soils per mil Isotopic ratio of 13C/12C in carbon dioxide referenced to PDB, measured with continuous flow on Finigan Delta Plus at CENA (per mil)
8 C_concentration_soils % Carbon content of soils in percent (%) analyzed by dry combustion at CENA (Centro de Energia Nuclear na Agricultura at the Unversity of Sao Paulo)
9 delta_15N_soils per mil Isotopic ratio of 15N/14N in carbon dioxide referenced to N2, measured with continuous flow on Finigan Delta Plus at CENA (per mil)
10 N_concentration_soils % Nitrogen content of soils in percent (%) analyzed by dry combustion at CENA (Centro de Energia Nuclear na Agricultura at the Unversity of Sao Paulo)
11 CN_ratio_soils Mass based ratio of soil carbon to nitrogen
12 Sand % Percent sand from soil texture analysis
13 Silt % Percent silt from soil texture analysis
14 Clay % Percent clay from soil texture analysis
15 Collection_date_soil_water_1 yyyy/mm/dd First sampling date (yyyy/mm/dd) for measurement of stable oxygen isotopes in soil water
16 delta_18O_soil_water_1 per mil delta 18O of the first set of extracted soil water relative to standard mean ocean water (SMOW) (per mil)
17 Collection_date_soil_water_2 yyyy/mm/dd Second sampling date (yyyy/mm/dd) for measurement of stable oxygen isotopes in soil water. (Provided 01-Sep (yy-mmm) date changed to 2001/09/01)
18 delta_18O_soil_water_2 per mil delta 18O of the second set of extracted soil water relative to SMOW (per mil)
19 Collection_date_soil_gas_1 yyyy/mm/dd First sampling date (yyyy/mm/dd) for measurement of stable oxygen and nitrogen isotopes in soil gases
20 N2O_mixing_ratio_soil_gas_1 ppb N2O mixing ratio (samples collected on date in column 19) for soil gases sampled using tubes installed at the various depths (ppb)
21 delta_15N_N2O per mil delta 15N compared to atmospheric N2 of N2O sampled from pore space (samples collected on date in column 19) (per mil)
22 Error_delta_15N_N2O per mil Precision of N2O delta 15N isotope measurement (per mil)
23 delta_18O_N2O per mil delta 18O compared to atmospheric N2 of N2O sampled from pore space (samples collected on date in column 19)
24 Error_delta_18O_N2O per mil Precision of N2O delta 18O isotope measurement (per mil)
25 Collection_date_soil_gas_2 yyyy/mm/dd Second sampling date (yyyy/mm/dd) for measurement of stable oxygen and nitrogen isotopes in soil gases
26 N2O_mixing_ratio_soil_gas_2 ppb N2O mixing ratio (samples collected on date in column 25) gases sampled using tubes installed at the various depths reported in parts per billion (ppb)
Missing data are represented by -9999

Example Data Records:

ID,Site,Pit_ID,Depth ,Collection_date_soils,Bulk_density,delta_13C_soils,C_concentration_soils,delta_15N_soils,
N_concentration_soils,CN_ratio_soils,Sand,Silt,Clay,Collection_date_soil_water_1, delta_18O_soil_water_1,
Collection_date_soil_water_2,delta_18O_soil_water_2,Collection_date_soil_gas_1,N2O_mixing_ratio_soil_gas_1,
delta_15N_N2O,Error_delta_15N_N2O,delta_18O_N2O,Error_delta_18O_N2O,Collection_date_soil_gas_2,
N2O_mixing_ratio_soil_gas_2

1A,km 83,C A,0-5,2000/07/21,-9999,-28.64,4.33,10.2,
0.34,12.9,-9999,-9999,-9999,2000/07/08,-9999,
2001/09/01,-9999,2001/11/16,-9999,
-9999,-9999,-9999,-9999,2002/03/15,
-9999
1B,km 83,C A,0-5,2000/07/21,0.81,-28.45,4.56,9.92,
0.36,12.59,31,8,61,2000/07/08,-5.13,
2001/09/01,-1.94,2001/11/16,353.1,
4.91,0.06,19.88,0.83,2002/03/15,
-9999
2,km 83,C A,10,2000/07/21,0.9,-27.4,1.79,11.77,
0.16,11.04,18,7,75,2000/07/08,-4.18,
2001/09/01,-2.77,2001/11/16,440.34,
3.92,0.006,19.8,0.24,2002/03/15,
648.39
...
13,km 67 Seca Floresta control,CF A,0,2000/07/21,0.96,-28.89,4.52,8.45,
0.33,13.75,12,10,78,2000/07/08,-4.55,
2001/09/01,-0.61,2001/11/22,392.6,
-0.64,0.24,17.61,0.36,2002/03/19,
-9999
14,km 67 Seca Floresta control,CF A,10,2000/07/21,0.96,-27.5,2.17,9.71,
0.18,11.82,12,14,74,2000/07/08,-3.83,
2001/09/01,-1.54,2001/11/22,425.3,
3.61,0.18,19.92,0.36,2002/03/19,
808.37
...

Data Application and Derivation:

Tropical forest soils are the largest natural source of N2O to the atmosphere (Matson and Vitousek 1990). The use of stable isotope composition of N and O in atmospheric N2O and its sources has been proposed as a way to better constrain the global N2O budget. Variations in the flux and isotopic signatures of N2O from tropical soils reflect the microbiological processes that produce and consume N2O as well as the physical controls of the rate of N2O movement from soil to the atmosphere (Perez et al. 2000, 2001). Understanding the relative contribution of mechanisms responsible for such variability will provide new tools for extrapolating stable isotope results into large scales.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Isotopic composition of nitrous oxide
The uncertainty in N2O isotopic signature, determined by repeated measurements of an N2O isotope standard, was plus/minus 0.2 per mil and plus/minus 0.3 per mil for 15N and 18O, respectively. The delta 15N and delta 18O values are expressed relative to atmospheric N2 and Vienna-standard mean ocean water (V-SMOW), respectively.

Nitrous oxide concentration
N2O mixing ratios were determined by collection of 20 mL nylon syringes in the soil depth probes and measurement by electron capture detector (ECD) gas chromatography. Calibration curves with two N2O standards (400 and 800 ppb) were made each sampling day. The uncertainty of the method based in the calibration curves with n=3 for each standard is plus/minus 5 ppb.

Amount and isotopic composition of soil carbon and nitrogen
The errors of %C, %N, delta 13C and delta 15N are calculated based on repeated analysis of standards of known isotopic composition. Their values are plus/minus 0.05%, plus/minus 0.1%, plus/minus 0.1 per mil and plus/minus 0.2 per mil for %C, %N, delta 13C, and delta 15N, respectively.

18O isotopic composition of soil water
The delta 18O values are expressed relative to the Vienna-standard mean ocean water (V-SMOW). The method uncertainty was plus/minus 0.1 per mil based on repeated analysis of standard materials.

Process Description:

Data Acquisition Materials and Methods:

Soil collection
Soils were collected from the Tapajos National Forest (TNF) near Santarem, Para state, Brazil. Soils from three primary forest sites were collected: a clay-rich (Oxisol), a sandy clay loam (Ultisol) and sandy loam (Ultisol) (described in Silver et al., 2000; Telles et al., 2003), and one set of samples from an Oxisol soil located in a forest dry down experiment (Seca Floresta) located in the km 67 site of the TNF (for this site details see Nepstad et al. 2002). The soil texture was determined at 0-5, 10, 25, 75, 100 and 200 cm of depth at the km 83 site. The texture classification at deeper layers shows that the sandy clay loam soil become a clay textured soil.

Amount and isotopic composition of TN
The fresh soils samples stored at 4 degrees C were taken to the Laboratorio de Ecologia Isotopica at CENA where they were dried at 60 degrees C for 24 hours. Samples were sieved (2 mm) and milled, and total carbon and total nitrogen content and 15N isotopic composition were determined by CF-EA-IRMS. The nitrogen content analyzed this way is the sum of organic and inorganic N and is reported as percentage of total soil mass.

Soil depth N2O mixing ratio sampling collection
For the Brazilian clay, sandy clay loam, and sandy loam, we dug a pit of 2 meters depth where we inserted 2 m of 1/8 inch (outer diameter) stainless steel tube probes at 10, 25, 75, 100, and 200 cm on one wall of the pit. One end of the probe had holes to allow soil air flow in and the other end had a 1/8 inch Swagelok fitting with a septum to collect the air samples with a syringe. We used one of the pit walls to determine physical parameters (bulk density and water content) and soil samples for nutrient soil analysis. We used a 20 ml syringe to collect soil air at each depth to determine N2O concentration. We flushed the first 20 ml of air to avoid possible N2O dilution within the probe (due to the probe length). At this site we sampled soil air for N2O mixing ratios and N2O stable isotope determinations at 0, 10, 25, 75, 100, and 200 cm of depth, as well as for water content, concentrations and isotopic composition of total carbon (TC) and nitrogen (TN), and soil nutrient (NH4+ and NO3-) concentrations. At the Seca Floresta site the same parameters were measured at 10, 25, 50, 100, 200, 300, 700, and 1,100 cm depth in a pit that was already being monitored monthly for trace gases concentrations (Davidson et al., unpublished results).

Stable isotope sampling collection
The samples for stable isotope analysis were collected using a N2O collection system that consisted of an evacuated stainless steel canister attached to a tee with a septum in one end and a drierite/ascarite trap (for removal of CO2 and H2O) at the other end. The other end of the drierite/ascarite trap was connected to either the chamber placed on the soil surface, or the soil probe at each particular depth. The evacuated can was filled with the gas sample following the procedure described elsewhere [Perez et al., 2006]. After a 2-minute equilibration period, the canister valve was closed and the sample stored until it was analyzed at UC Irvine using a Finnigan MAT 252 isotope ratio mass spectrometer operated in continuous flow mode coupled with an online custom-made preconcentrator and gas chromatograph.

Isotopic composition of nitrous oxide
The samples stored in stainless steel canisters were transported to the University of California Irvine. In S. Tyler\'s lab, we used a custom-built gas pre-concentrator for N2O stable isotope analysis attached to a isotope ratio mass spectrometer. The procedure was as follows: We transferred the samples into glass bulbs (either 100 mL or 250 mL in volume) equipped with two valves. The smaller glass bulbs were chosen for the samples with the highest N2O concentration. A sample placed in a bulb was connected to the inlet of the pre-concentrator. High-flow ultra-high purity helium (25 mL/min) carried the sample first to an ascarite and then to a MgClO4 trap (to remove CO2 and H2O), then to a Nafion dryer (to further remove H2O; Perma Pure, Toms River, New Jersey, USA), and finally to the next trap in line where the N2O was condensed cryogenically (195 degrees K) and the other non-condensable gases were removed (N2, O2, CH4, CO). Enough helium was used to flush the sample bulb volume three times and ensure that all the sample was extracted from the bulb. The N2O on the first trap was released by warming it to room temperature and transferring it cryogenically to a Porapak Q trap (Alltech, Deerfield, Illinois, USA) at room temperature to remove the hydrocarbons remaining in the sample. Finally, the sample was transferred into a cryofocusing trap (Poraplot Q, Alltech) before its injection into a gas chromatograph (GC). The sample was transferred to the GC by a stream of low-flow UHP helium (3 mL/min) and the N2O was separated from remaining traces of CO2 by a 25-m Poraplot Q capillary column (Alltech). Finally the bulk delta 18O and delta 15N isotopic compositions were measured by the Finnigan MAT model Delta XL isotope ratio mass spectrometer (ThermoElectron, Waltham, Massachusetts, USA) connected to the GC via an open split.

References:

Matson, P.A. and P.M. Vitousek. 1990. An ecosystem approach to the development of a global nitrous oxide budget. BioScience 40: 672-677. doi:10.2307/1311434

Moreira, M.Z., L.S.L. Sternberg, L.A. Martinelli, R.L. Victoria, E.M. Barbosa, L.C.M. Bonates and D. Nepstad. 1997. Controls of transpiration to forest ambient vapour based on isotopic measurements. Global Change Biology 3:439-450. doi:10.1046/j.1365-2486.1997.00082.x

Mulvaney, R.L. 1996. Nitrogen: inorganic forms Pages 1123-1184 in D.L. Sparks (ed) Methods of Soil Analysis. Part 3. Chemical methods. Soil Science Society of America, Madison WI, USA

Nepstad, D.C., P. Moutinho, M.B. Dias, E. Davidson, G. Cardinot, D. Markewitz, R. Figueiredo, N. Vianna, J. Chambers, D. Ray, J.B. Guerreiros, P. Lefebvre, L. Sternberg, M. Moreira, L. Barros, F.Y. Ishida, I. Tohlver, E. Belk, K. Kalif, and K. Schwalbe. 2002. The effects of partial throughfall exclusion on canopy processes, aboveground production, and biogeochemistry of an Amazon forest. Journal of Geophysical Research- Atmospheres 107: 8085.

Perez, T., S.E. Trumbore, S.C. Tyler, E.A. Davidson, M. Keller, and P.B. de Camargo. 2000. Isotopic variability of N2O emissions from tropical forest soils, Global Biogeochemical Cycles, 14(2):525-535. doi:10.1029/1999GB001181

Perez, T., S.E. Trumbore, S.C. Tyler, P.A. Matson, I. Ortiz-Monasterio, T. Rahn, and D.W.T. Griffith. 2001. Identifying the agricultural imprint on the global N2O budget using stable isotopes, Journal of Geophysical Research-Atmospheres, 106(D9):9869-9878. doi:10.1029/2000JD900809

Perez, T., Garcia-Montiel, D., Trumbore, S.E., Tyler, S. C., de Camargo, P., Moreira, M., Piccolo, M. and Cerri, C. 2006. Nitrous oxide nitrification and denitrification 15N enrichment factors from Amazon forest soils. Ecological Applications. 16(6) 2153-2167.

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

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: art.no. 1040. doi:10.1029/2002GB001953

Skip navigation linksHOME | ABOUT | LIBRARY | NEWS ARCHIVE | CONTACTS | INVESTIGATIONS | LOGISTICS | DATA |TRAINING & EDUCATION

NASA logo
ORNL DAAC
Get Acrobat Reader