BOREAS TGB-12 Soil Carbon Data over the NSA

Summary:

The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon 
concentration in soil gases, and rates of soil respiration at several sites to 
estimate the rates of carbon accumulation and turnover in each of the major 
vegetation types.  TGB-12 data sets include soil properties at tower and selected 
auxiliary sites in the BOREAS NSA and data on the seasonal variations in the 
radiocarbon content of CO2 in the soil atmosphere at NSA tower sites.  The 
sampling strategies for soils were designed to take advantage of local fire 
chronosequences, so that the accumulation of C in areas of moss regrowth could be 
determined.  These data are used to calculate the inventory of C and N in moss 
and mineral soil layers at NSA sites and to determine the rates of input and 
turnover (using both accumulation since the last stand-killing fire and 
radiocarbon data).  This data set includes physical parameters needed to 
determine carbon and nitrogen inventory in soils.  The data were collected 
discontinuously from August 1993 to July 1996.  The data are stored 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-12 Soil Carbon Data over the NSA

1.2 Data Set Introduction

The data presented here include physical parameters needed to determine carbon 
and nitrogen inventory in soils (bulk density, %C (both as organic C and CaCO3), 
%N, C/N ratio in organic matter) as well as 14C measurements of organic matter.  
Soil moisture data (good only for the day of collection) and brief descriptions 
of soil horizons are also included.

1.3 Objective/Purpose

The objectives of the research were:
1) To estimate rates of carbon input, turnover, and accumulation in the soils of 
each of the major vegetation types at the BOREAS study sites.  The primary tool 
will be measures of 14C content in soils, litter, soil atmospheres, measurements 
of CO2 emissions from the soil.  
2) To relate our estimates of dynamics of soil carbon to ecosystem models of the 
carbon cycle, to other measures of C cycling dynamics, to regional models of soil 
carbon accumulation, and to spatial and temporal models of soil moisture and 
drainage. 

1.4 Summary of Parameters

The key parameters include brief description of the sample/horizon (e.g. brown 
decomposed moss, clay), soil pH, soil moisture, bulk density, organic carbon and 
nitrogen content, inorganic carbon content, and radiocarbon (14C) content.

1.5 Discussion

Carbon inventories and 14C give information are needed to determine C storage, as 
well as to determine the accumulation rate of C (in non-steady state systems) or 
the turnover rate of C (in systems where C turnover rate is less than soil or 
disturbance age).  These data are checked using the isotopic composition of 
respired CO2 (which will reflect the 14C content of root respiration and 
decomposing organic matter), and by a knowledge of soil C inputs and losses.  See 
section 3 (below) for details.

1.6 Related Data Sets

BOREAS TGB-12 Radon222 Soil Data over the NSA
BOREAS TGB-12 Soil Carbon Isotope Data over the NSA
BOREAS TGB-01 Soil CH4 and CO2 Profile Data over the NSA
BOREAS TGB-03 Soil CO2 and CH4 Profile Data over the NSA

2. Investigator(s)

2.1 Investigator(s) Name and Title

Susan Trumbore
Department of Earth System Science
UC Irvine 

Jennifer Harden
US Geological Survey
Menlo Park, CA 

Eric Sundquist
US Geological Survey
Woods Hole, MA 

2.2 Title of Investigation

Input, Accumulation and Turnover of Carbon in Boreal Forest Soils

2.3 Contact Information

Contact 1
Susan Trumbore
Earth System Science
University of California Irvine
Irvine, CA 

Contact 2
Jennifer Harden
US Geological Survey
Menlo Park, CA 
415-329-4949(Harden)
415-329-4940 (O'Neill)
415-329-4936 (Fax)
harden@usgs.gov

Contact 3
Eric Sundquist
US Geological Survey
Woods Hole, MA 
(508)457-2397
sundquist@nobska.wr.usgs.gov

Contact 4
Greg Winston
US Geological Survey
Woods Hole, MA 
(508)457-2397

Contact 5
Sara Conrad
Raytheon STX Corporation
NASA Goddard
Greenbelt, MD 
(301) 286-2624
(301) 286-0239 (FAX)
Sara.Golightly@gsfc.nasa.gov

3. Theory of Measurements

Soil moisture and soil C and N inventory are relatively common and 
straightforward measurements to make and will not be discussed in detail here.

14C is produced in the stratosphere by the 14N (n,p) 14C reaction.  The 14C atom is 
oxidized rapidly to 14CO, which has a lifetime of months before it is oxidized to 
14CO2.  Most 14C production occurs in the stratosphere, but the long lifetime of 
CO2 enables 14CO2 to become well mixed throughout the troposphere.   The steady 
state 14C content of the atmosphere is determined by the exchange of carbon in CO2 
with that in ocean and biospheric reservoirs.  Because of the relatively rapid 
cycling of carbon between the atmosphere and living biomass, most plants maintain 
a 14C specific activity (or 14C/12C ratio corrected for mass-dependent isotope 
fractionation effects) that equals that of atmospheric CO2.  Similarly, animals 
reflect the 14C/12C of the plants (or animals) they consume.  Upon the death of an 
organism, the 14C in its tissues is no longer replenished, and decays with a half 
life of 5730 years. If the tissue remains intact and isolated from exchange, the 
14C/12C ratio may be used to indicate the time since the death of the organism.  
This is the basis for radiocarbon dating.  

Calculation of a radiocarbon age requires the assumption that the 14C content of 
the carbon originally fixed in plant tissues equaled that of the atmospheric CO2 
in 1950 (0.95 times the activity of oxalic acid, or Modern).  In fact, the 14C 
content of the atmosphere has varied with time because of changes in the 
production rate of 14C (cosmic ray flux and magnetic field variations) and 
because of changes in the distribution of carbon among ocean, biosphere and 
atmospheric reservoirs.  These variations, deduced from the 14C content of 
cellulose of known age taken from the annual growth rings of trees, are generally 
less than 10% over the past 7,000 years.  More recent changes in the 14C content 
of atmospheric CO2 have resulted from dilution by 14C-free fossil-fuel-derived 
carbon and by the production of 14C during atmospheric testing of thermonuclear 
weapons (bomb 14C).  The latter effect dominates other natural and fossil fuel 
effects, as the atmospheric burden of 14C was approximately doubled in the few 
years preceding the implementation of the Nuclear Test Ban Treaty in 1964. This 
isotopic spike in the global carbon system provides a means for radiocarbon to be 
a useful tracer of carbon cycle processes on time scales of decades.  

We express 14C data in the geochemical D notation, the deviation in parts per 
thousand (per mil) from an absolute standard (95 times the activity of NBS oxalic 
acid measured in 1950).  In this notation, zero equals the 14C content of 1895 
wood, positive values indicate the presence of 'bomb' radiocarbon, and negative 
values indicate the predominance of C fixed from the atmosphere more than several 
hundred years ago.  

One important correction made in calculating the D14C value is the 13C 
concentration is needed to account for isotopic fractionation effects.  For 
example, consider that the d13C difference between atmospheric CO2 and carbon 
fixed during photosynthesis by C3 plants is approximately 20.  Since the mass 
difference between 12 and 14 is twice that between 12 and 13, the fractionation 
of 14C will be roughly twice that of 13C.  The 14C contents of a tree and the CO2 
that it is fixing through photosynthesis will differ by approximately 40%.  To 
account for fractionation effects, the sample (with d13C of d) and standard are 
corrected to a constant 13C content.  The standard oxalic acid is corrected in 
the same way, to -19 per mil (see references in section 19 for more detail).

For seeds and deciduous leaves that represent a single year's growth, the 14C 
content of recent samples may be used to determine the age of a sample to within 
a year or two.  The 14C content of the sample is compared to the 14C record of 
atmospheric C in the Northern Hemisphere (see Burcholadze reference, in section 
19 for an example).  Evergreen needles, that may average several years' growth, 
will be less easily interpreted. 

For samples prior to 1960, radiocarbon ages in years may be calculated from the 
given Delta values as -8033*(ln(Delta*.995/1000 +1)).  The conventional 
radiocarbon age must be converted to a calibrated age using the tree-ring based 
calibration curves that correct for known variations in atmospheric 14C over 
time.  Both ages are usually rounded to the nearest decade or pentad.  

One application of radiocarbon to soil science lies is the 14C dating of charcoal 
and plant macrofossils to determine the accumulation rate of C in vertically 
aggrading soils (peat or moss). 

Unlike the closed systems represented by intact macrofossils, such as seeds or 
pollen, bulk Soil Organic Matter (SOM) is a heterogeneous reservoir with a 
variety of turnover times, to which carbon is continuously added (as new plant 
matter) and lost (as leached organic carbon or CO2).  The radiocarbon content of 
SOM can not be interpreted as a 'date', but represents the average age of a 
carbon atom in this reservoir.

The breakdown of C into faster and slower cycling pools may be determined by 
combining several approaches (see the articles in the reference list for more 
information).

For soils that are accumulating organic matter, the Harden et al (1992) approach 
is used.  The upward accumulation of carbon in feathermoss is modeled as a time 
sequence described by inputs and decomposition according to the following 
equation:

dC/dt = I - kC                      (1)
and  Ct = I/k*(1- exp-k*t)          (2)

where C is carbon mass in units of mass per area, t is time, I is input rate in 
mass per area per year, and k is a decomposition coefficient in units of time-1.  
This approach assumes that decomposition is proportional to total mass.  

Two approaches were used:
(1) measuring the dC/dt for mosses in stands of different ages of recovery since 
fire and fitting a curve of C and time with equation (2). At each identified 
post-burn site, transects were conducted across a variety of soil drainage 
classes to collect samples for inventories of biomass (trees and understory), 
accumulating slash, moss, and soil . 

(2)  Using 14C to determine time to construct a curve of cumulative C inventory 
versus time at a single site (to which equation (2) is fit and I and k 
determined).  In moss layers, we use the bomb-14C signal recorded in growing 
mosses (particularly Sphagnum); in humic and mineral soil layers, we use standard 
radiocarbon 'age' calculations.  This approach assumes that time information, 
derived from macrofossils picked from the soil or moss sample, is representative 
of C dynamics for the bulk sample (not particularly true for feather mosses).

4. Equipment:

4.1 Sensor/Instrument Description

Shovel, eyes, and sample bags
Lab Equipment - Carlo Erba NA1500 carbon and nitrogen combustion analyzer; vacuum 
lines for purification of CO2 from combusted samples and graphite target 
preparation.  Accelerator mass spectrometer used for 14C measurement is described 
in Southon et al., and Trumbore (in press)

4.1.1 Collection Environment

Samples were collected under all environmental conditions.

4.1.2 Source/Platform

Ground.

4.1.3 Source/Platform Mission Objectives

None given.

4.1.4 Key Variables

Soil temperature, sample depth, air temperature, site descriptions, del13C, 
del14C, CO2 Concentration, pH of the soil, volumetric and gravimetric soil, bulk 
density, and organic C and N.

4.1.5 Principles of Operation

None given.

4.1.6 Sensor/Instrument Measurement Geometry

None given.

4.1.7 Manufacturer of Sensor/Instrument

None given.

4.2 Calibration

4.2.1 Specifications

None given.

4.2.1.1 Tolerance

None given.

4.2.2 Frequency of Calibration

None given.

4.2.3 Other Calibration Information

None given.

5. Data Acquisition Methods

Special pits were equipped with thermistors (for monitoring soil temperature), 
Time Domain Reflectometry (TDR) probes (for monitoring soil water content), and 
soil gas probes (1/8" stainless steel tubing, perforated at one end and inserted 
50 to 100 cm laterally into the soil pit wall, capped with 1/8" swagelock union 
fittings sealed with a septum).  Further details are given in Winston et al. 
(submitted), and in section 4, below.

Gas samples were obtained using gas-tight syringes, <10cc for soil CO2 (made 
using a Licor and the method of Davidson and Trumbore (1995) and CH4 measurements 
(made by FID gas chromatography).  Soil samples are sieved (to <2mm) to remove 
rocks and large roots.  We have quantified how much of this material was removed, 
and estimated the amount of C and N contained in the larger fractions.  We report 
bulk density or carbon inventory data of the <2mm fraction, then add the >2mm 
portion back in to determine total bulk density and C inventory. In clay soils, 
this is a less important correction than in the sandy, gravelly soils (an example 
of where these data are needed is in the very gravelly soils found at the NSA YJP 
site).  The samples are then homogenized, split, and in some cases ground to <100 
mesh for chemical analyses.  

Laboratory measurements are described below:

Bulk density.  Bulk density is measured by determining the oven dry weight of a 
specific volume of soil.  Field sampling utilized a 'box' of known area for 
collection of organic samples in upper soil horizons (such as mosses and litter 
layers). The area sampled was generally 12 cm x 12 cm.  Samples of generally less 
than 7cm depth were taken.  Note that the depths are not as well determined as 
the area, therefore areally expressed data (gC/cm2) should be used in these 
layers with more confidence than the bulk density data.  

In deeper soil layers, the bulk density data were measured using several small 
cores (roughly 3.5 cm diameter by 5 cm in length) that were pushed into the pit 
wall.  

%N, %C and %CaCO3.  These measurements were performed with a commercial 
combustion analyzer (Carlo Erba NA1500).  This instrument flash-combusts organic 
matter, oxides all C to CO2, and reduces all N to N2, then separates these gases 
chromatographically, and detects them with a thermal conductivity detector.  The 
detector response for C and N is determined by combusting known quantities of C 
and N-containing pure compounds.  Combusting empty capsules determine blanks, due 
to the presence of small amounts of C in the tin boats used to hold the sample 
(for C) or to small amounts of residual air (for N2).  The combustion analyzer 
will oxidize both organic carbon and inorganic carbonates to CO2.  The Lake 
Agassiz clays underlying many of the soils in the NSA contain significant amounts 
of inorganic CaCO3. To determine both CaCO3 and organic C content, each sample is 
analyzed twice: once for total carbon and once after it has been acidified to 
remove calcium carbonate.  The %CaCO3 is then the Total %C minus the %C due to 
organics. Uncertainties are still being investigated for this equipment in the 
Irvine laboratory, but in general %C values are reproducible to +/- 0.05%C 
(organic) and %N.

14C.  Carbon-14 is measured by Accelerator mass spectrometry of graphite targets 
prepared from CO2 (see one of several references, including Trumbore, 1995). 
Samples (of 1-2 mg carbon equivalent) are combusted in vacuum in quartz tubes 
with cupric oxide wire at 900 Celsius.  The resulting CO2 is purified 
cryogenically, then reduced to graphite coating cobalt powder in a sealed Pyrex 
tube at 500-550 Celsius with zinc and titanium hydride powder. Accelerator mass 
spectrometry measurements were made at the Lawrence Livermore National Laboratory 
Center for Accelerator Mass Spectrometry. One sigma precision is usually +/- 8-10 
per mil (.8-1.0 % Modern) and overall accuracy (based on repeated measurements of 
substandards prepared in the same way as samples) is 1.0 - 1.5% of Modern (10 - 
15 per mil).  We have noted what was measured for 14C, as specific fractions of 
the organic C are measured; these fractions include macrofossils (sphagnum 
leaves, fine root hairs, deciduous leaves, or charcoal), and chemically treated 
samples (residue after treatment with 0.5N HCl).

6. Observations

6.1 Data Notes

None given.

6.2 Field Notes

None given.

7. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

The coordinate information for the various sampled sites is incomplete in the 
following lists.  Where latitude and longitude coordinates exist, they are 
expressed in degrees and in reference to the North American Datum 1983 (NAD83).

     Sites with Coordinate Information
-------------------------------------------------
Site Name/Label        Latitude        Longitude
---------------        --------       ----------
GR1, Gillam Road       55.9055 N     97.7087 W
GR2, Gillam Road       55.9082 N     97.7003 W
GR3, Gillam Road:      55.906 N      97.7098 W
GR4, Gillam Road:      55.9041 N     97.7063 W
GR5, Gillam Road:      55.9055 N     97.7087 W
Gillam Road Transect   55.9055 N     97.7087 W
       (The transect starts 100m SW of so82715C, where GR5 was sampled in 
        detail and continues SW parallel to road with sampling approximately 
        every 100m.)
NSA-FEN:               55.91481 N    98.42072 W
NSA-OBS:               55.88007 N    98.48139 W
NSA-OBS:               55.88007 N    98.48139 W
OJP1:                  55.9287 N     98.6248 W
OJP2:                  55.9287 N     98.6248 W
NSA-OJP:               55.92842 N    98.62396 W
YJP1:                  55.8952 N     98.28686 W
NSA-YJP:               55.89575 N    98.28706 W
FF1:                   55.906 N      98.949 W
SLJ1:                  55.0667 N     98.5083 W

Sites with No Coordinate Information Available
-----------------------------------------------
Site Name/Label       Location Description
---------------       ------------------------
SLJ2                  Transect, approximately 500m NNW of SLJ1
SLJ3                  Transect, approximately 500m NNW of SLJ2
SLJ4                  Transect, approximately 500m NNW of SLJ3
SLJ5                  Transect, approximately 500m NNW of SLJ4
SLJ6                  Transect, approximately 500m NNW of SLJ5
SLJ7                  Transect, approximately 500m NNW of SLJ6
SLJ8                  Transect, approximately 500m NNW of SLJ7
FFJ11                 Footprint River, Footprint fire 1989 burn site,
                      west side of Footprint River Bridge.
FFJ12                 Footprint River, Footprint River, 1989 burn,
                      west side of Footprint River bridge, poorly drained site.
SOAB1                 No location information is available.
SOBA0                 Soab River 1956 burn, Site 0 on the transect; on the 
                      ridge of the SOAB 1956 burn.
SOBA1                 Soab River,1956 burn, South of Thompson on Hwy 391/6
                      just north of the Soab River on the west side of road.
SOBA2                 Soab River,1956 burn, 500m North of SOBA1
SOBA3                 Soab River,1956 burn, 500m North of SOBA2
SOBA4                 Soab River,1956 burn, 500m North of SOBA3
SOBA5                 Soab River,1956 burn, 500m North of SOBA4
SOBA6                 Soab River,1956 burn, 500m North of SOBA5
SOBA7                 Soab River,1956 burn, 500m North of SOBA6
SOBA8                 Soab River,1956 burn, 500m North of SOBA8
SOBA9                 Soab River,1956 burn, 500m North of SOBA9
SOBA10                Soab River,1956 burn, 500m North of SOBA9
SOBA11                Soab River,1956 burn, 500m North of SOBA10
SOBA12                Soab River,1956 burn, South of Thompson just north of 
                      the Soab River.
SOBA13                Soab River,1956 burn, South of Thompson just north of 
                      the Soab River on Hwy 391.
SOBA14                Soab River,1956 burn, South of Thompson just north of 
                      the Soab River on Hwy 391.
SOBH1                 Soab River
T3H                   No location information is available.
FFJ1                  Footprint fire 1989 burn site, far into Footprint burn, 
                      approximately 1Km north of FF1.
FFJ2                  near the Footprint RiverAlong the FFJ transect between 
                      FFJ1 and 3.
YJPK1                 Young Jack Pine, 1964 burn, Veldhuis Map name:  
                      Partridge soil; code pcp
YJPK2                 Young Jack Pine, 1964 burn, Veldhuis Map name:  
                      Partridge soil; code pcp
BOG                   No location information available.
OBS11                 Old Black Spruce, Veldhuis Mapped name: Sipewisk.
OBSF3                 Old Black Spruce, End of TGB spur, 2.5 m east of small 
                      corral.
OBSF4                 Old Black Spruce, NW corner of boardwalk-TGB spur, 3m N 
                      and 3m W of intersection of spur and boardwalk.
OBSP9                 Old Black Spruce, Veldhuis mapped name: Nicohols Lake (NIC)
OBS1                  Old Black Spruce, Site is very wet, seasonally if not 
                      perennially somewhat frozen.  Bear east on catwalk, 
                      south on first spur, east about 5m
OBS2                  near Old Black Spruce
FW10                  Gillam Road: 1992 burn, near 89/90 km marker on Gillam Road
GRS1                  Gillam Road: 1994 burn.
GRC12                 Gillam Road: unburned control for 1992 burn, near 89/90 
                      km marker on Gillam Road, North side of road, across 
                      from 1992 burn.
GRC13                 Gillam Road: unburned control for 1992 burn, near 89/90 
                      km marker on Gillam Road, North side of road, across 
                      from 1992 burn.
GRJ11                 Gillam Road: Cabin site, 1964 burn.
Gillam Road:          Near 89/90 marker on Gillam Road.
FW3                   Gillam Road: Near 89/90 marker on Gillam Road.
FW9                   Gillam Road: 1992 burn, near 89/90 km marker on Gillam Road

7.1.2 Spatial Coverage Map

Not available.

7.1.3 Spatial Resolution

None given.

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

Soil Carbon measurements were made from Aug 1993 to Jul 1996.

7.2.2 Temporal Coverage Map

Not applicable.

7.2.3 Temporal Resolution

The temporal resolution of the measurements was variable.

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file 
(tgb12scd.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file (tgb12scd.def).

8. Data Organization

8.1 Data Granularity

All of the BOREAS TGB-12 Soil Carbon Data over the NSA data are contained in one 
dataset.

8.2 Data Format(s)

The files contain numerical and character fields of varying length separated by 
commas. The character fields are enclosed with single apostrophe marks. There are 
no spaces between the fields.  Sample data records are shown in the companion 
data definition file (tgb12scd.def).

9. Data Manipulations

9.1 Formulae

9.1.1 Derivation Techniques and Algorithms

None.

9.2 Data Processing Sequence

9.2.1 Processing Steps

None given.

9.2.2 Processing Changes

None given.

9.3 Calculations

9.3.1 Special Corrections/Adjustments

None given.

9.3.2 Calculated Variables

None given.

9.4 Graphs and Plots

None given.

10. Errors

10.1 Sources of Error

None given.

10.2 Quality Assessment

10.2.1 Data Validation by Source

None given.

10.2.2 Confidence Level/Accuracy Judgement

None given.

10.2.3 Measurement Error for Parameters

None given.

10.2.4 Additional Quality Assessments

None given.

10.2.5 Data Verification by Data Center

The data were examined for general consistency and clarity.

11. Notes

11.1 Limitations of the Data

None given.

11.2 Known Problems with the Data

None given.

11.3 Usage Guidance

None given.

11.4 Other Relevant Information

None given.

12. Application of the Data Set

None given.

13. Future Modifications and Plans

None given.

14. Software

14.1 Software Description

None given.

14.2 Software Access

None given.

15. Data Access

15.1 Contact Information

Ms. Beth Nelson
BOREAS Data Manager
NASA GSFC
Greenbelt, MD 
(301) 286-4005
(301) 286-0239 (fax)
Elizabeth.Nelson@gsfc.nasa.gov

15.2 Data Center Identification

See 15.1.

15.3 Procedures for Obtaining Data

Users may place requests by telephone, electronic mail, or FAX.

15.4 Data Center Status/Plans

The TGB-12 soil carbon data are available from the EOSDIS ORNL DAAC (Earth 
Observing System Data and Information System) (Oak Ridge National Laboratory) 
(Distributed Active Archive Center). 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 ASCII files.

17. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

17.2 Journal Articles and Study Reports

Donahue, D. J., T. W. Linick and A. J. T. Jull, Isotope-ratio and background 
corrections for accelerator mass spectrometry radiocarbon measurements, 
Radiocarbon 32: 135-142 (1990).

Goh, K. M., Carbon dating, chapter 8 (pp. 125 - 145), in, D. C. Coleman and B. 
Fry, Carbon isotope techniques, Academic Press, San Diego (1991)
Sellers, P., F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. 
Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). 

Sellers, P., F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. 
Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). 

Sellers, P., F. Hall, K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 
1994 Operations. NASA BOREAS Report (OPS DOC 94). 

Sellers, P., F. Hall, 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 
earlyresults from the 1994 field year. Bulletin of the American Meteorological 
Society. 76(9):1549-1577. 

Sellers, P., F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue (in press).

Southon, J., R., J. S. Vogel, S. E. Trumbore and others, Progress in AMS 
measurements at the LLNL spectrometer, Radiocarbon 34: 473 - 477 (1992).

Stuiver, M. and H.  Polach., Reporting of 14C data. Radiocarbon 19: 355-363 
(1977).

Taylor, R. E., A. Long, and R. Kra, eds., Radiocarbon after Four Decades: An 
interdisciplinary perspective, Springer-Verlag, NY,596 pp. (1992).

Trumbore,S. E.,  Comparison of carbon dynamics in two soils using measurements of 
radiocarbon in pre-and post-bomb soils. Global Biogeochemical Cycles 7:275-290 
(1993).

17.3 Archive/DBMS Usage Documentation

18. Glossary of Terms

None given.

19. List of Acronyms

    AMS     - Accelerator Mass Spectrometery
    BOREAS  - BOReal Ecosystem-Atmosphere Study
    BORIS   - BOREAS Information System
    DAAC    - Distributed Active Archive Center
    EOS     - Earth Observing System
    EOSDIS  - EOS Data and Information System
    GSFC    - Goddard Space Flight Center
    NASA    - National Aeronautics and Space Administration
    NSA     - Northern Study Area
    ORNL    - Oak Ridge National Laboratory
    PANP    - Prince Albert National Park
    SSA     - Southern Study Area
    URL     - Uniform Resource Locator

20. Document Information

20.1 Document Revision Date

    Written:   24-Jul-1994
    Last Updated: 04-Aug-1998

20.2 Document Review Date(s)

     BORIS Review:    25-Jul-1998
     Science Review: 

20.3 Document ID

20.4 Citation

The TGB-12 team plans to publish the data in a USGS open file report.  Please 
look for and reference the report or contact Susan Trumbore.

20.5 Document Curator

20.6 Document URL

Keywords
CO2, 14C, 13C, Soil Carbon, Organic Carbon, Inorganic Carbon

TGB12_Soil_Carbon
08/20/98