BOREAS TGB-12 222Rn Activity 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. Sampling strategies for soils were designed to take advantage
of local fire chronosequences, so that the accumulation of C in regrowing mosses
could be determined. All the data are used to (1) calculate the inventory of C
and N in moss and mineral soil layers at NSA sites (2) determine the rates of
input and turnover (using both accumulation since the last stand-killing fire
and radiocarbon data) and (3) link changes in soil respiration rate to shifts in
the 14C content of soil CO2 to determine the average 'age' respired CO2. These
222Rn activity data were collected from 15-NOV-1993 to 16-AUG-1994 over the NSA
sites. The data in this data set 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 222Rn Activity data over the NSA
1.2 Data Set Introduction
This dataset contains seasonal variations in the 222Rn soil gas concentrations.
The data presented represent sampling from the fall of 1993 to the summer of
1994.
1.3 Objective/Purpose
The objective of these data are to estimate rates of carbon input, turnover, and
accumulation in the soils of each of the major vegetation types at the BOREAS
study sites. In addition, the data will be used to relate the estimates of soil
carbon dynamics to ecosystem models of the carbon cycle, other measures of C
cycling dynamics, regional models of soil carbon accumulation, and spatial and
temporal models of soil moisture and drainage.
1.4 Summary of Parameters
222Rn Activity and soil depth were measured over the BOReal Ecosystem Atmosphere
Study (BOREAS) Northern Study Area (NSA).
1.5 Discussion
Carbon inventories together with 14C data determine C storage and 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 may be verified using the isotopic composition of respired CO2 (which will
reflect the 14C content of root respiration and decomposing organic matter), and
by the soil C inputs and losses.
1.6 Related Data Sets
BOREAS TGB-12 CO2 Flux Data over the NSA
BOREAS TGB-12 Soil Carbon Isotope Data over the NSA
BOREAS TGB-05 Fire History Map in Raster Format
BOREAS TE-18 LandSat Level 3 Land Cover Classification of NSA
BOREAS AFM-12 Land Cover Classification from AVHRR
BOREAS Regional Soils Data in Raster Format and AEAC Projection
BOREAS Soils Data over the SSA in Raster Format and AEAC Projection
BOREAS TGB-01 Soil CH4 and CO2 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 BOREAS NSA soils (TGB-12)
2.3 Contact Information
Contact 1
Jennifer Harden
US Geological Survey
Menlo Park, CA
Phone: 415-329-4949
FAX: 415-329-4936
e-mail: harden@usgs.gov
Contact 2
Susan Trumbore
Department of Earth System Science
University of California
Irvine, CA
Phone: 714-824-6142
FAX: 714-824-3256
e-mail: setrumbo@uci.edu
Contact 3
Eric Sundquist
US Geological Survey
Woods Hole, MA
Phone: 508-457-2397
e-mail: sundquist@nobska.wr.usgs.gov
Contact 4
Greg Winston
US Geological Survey
Woods Hole, MA
Contact 5
Sara K. Conrad
Raytheon STX Corporation
NASA/GSFC
Greenbelt, MD
(301)286-2624
(301)286-0239 (fax)
Sara.Golightly@gsfc.nasa.gov
3. Theory of Measurements
Special pits were instrumented with thermistors (for monitoring soil
temperature), 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.
222Rn gas samples were obtained using gas-tight syringes, 60 cc, were dried (by
passing through drierite), then allowed to fill an evacuated counting cell
coated with phosphor scintillant and decay counted. A Description of radon
sampling and analysis procedures is given in Davidson and Trumbore (1995).
4. Equipment:
4.1 Sensor/Instrument Description
As all of the equipment used in this project is common to many other projects
and no special procedures were used, we have minimized description detail in
this section, and refer the reader to appropriate publications.
Field equipment for soil collection was minimal, excepting the pH test kit
(LaMotte). Drying ovens were supplied by the BOREAS project for the NSA labs.
We brought our own scale, which was frequently checked using a calibration
weight.
Radon measurements were made using Pylon alpha scintillation counters.
4.1.1 Collection Environment
Samples were collected under all environmental conditions.
4.1.2 Source/Platform
Soil.
4.1.3 Source/Platform Mission Objectives
The objective was to determine the soil 222Rn Activity.
4.1.4 Key Variables
The key variables measured were 222Rn Activity and soil depth.
4.1.5 Principles of Operation
None given.
4.1.6 Sensor/Instrument Measurement Geometry
Not applicable.
4.1.7 Manufacturer of Sensor/Instrument
None given.
4.2 Calibration
Radon cell efficiencies were determined in the lab using background air and 226Ra
of known activity absorbed to manganese fibers and sealed in a tube. Counting
cell backgrounds were determined using ambient air (see Davidson and Trumbore,
1995, for details of radon measurement methods).
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.
5. Data Acquisition Methods
None Given.
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 North American Datum 1983 (NAD83) coordinates of the sites were:
Site Latitude Longitude
------ --------- ----------
NSA-OBS: 55.88007N 98.48139W
NSA-OJP: 55.92842N 98.62396W
NSA-YJP: 55.89575N 98.28706W
NSA-Gillam Road: 55.9055 N 97.70872W
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 gas flux and concentration measurements were made from Nov 1993 to Aug
1994.
7.2.2 Temporal Coverage Map
Not applicable.
7.2.3 Temporal Resolution
The temporal resolution of the measurements was variable. Some sites were
visited once and other were visited multiple times.
7.3 Data Characteristics
Data characteristics are defined in the companion data definition file
(tgb12rad.def).
7.4 Sample Data Record
Sample data format shown in the companion data definition file (tgb12rad.def).
8. Data Organization
8.1 Data Granularity
All of the BOREAS TGB-12 222Rn Activity 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 (tgb12rad.def).
9. Data Manipulations
9.1 Formulae
9.1.1 Derivation Techniques and Algorithms
Methods for calculating radon and radiocarbon data are given in Davidson and
Trumbore (1995) and Trumbore (1995).
9.2 Data Processing Sequence
None given.
9.2.1 Processing Steps
None given.
9.2.2 Processing Changes
None given.
9.3 Calculations
None given.
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
Sources of error include inaccuracies in soil collection, instrument errors
during running of samples.
10.2 Quality Assessment
10.2.1 Data Validation by Source
Analyzing known-value standards as unknowns assesses errors in laboratory
procedures. The accuracy of measurement is defined as the standard error of the
mean of the analyses.
Errors for bulk soil analyses are harder to estimate. The most uncertain terms
are bulk density (largely due to uncertainties in horizon thickness). The
calculation of grams/cm2 is therefore less prone to error than grams/cm3. We
estimate the uncertainty in bulk density at approximately 10%, but it is
difficult to ascertain as lateral and vertical heterogeneity is large (therefore
a 'replicate' sample cannot truly be taken in the field). The error in bulk
density will propagate through to other values, such as volumetric moisture
content.
There are many sources of error in flux measurements. The ones associated with
our methods are detailed in Stephens et al (submitted). Errors involved in soil
gas sampling include: the volume of soil air space sampled (500 cc to 1 liter)
represents a far larger volume of soil. Thus the depth assigned to a soil gas
sample (i.e. the depth of the probe) may not represent the average for the
interval integrated in the gas sample taken from it (that is, air may be pulled
down from above or up from below). We give only analytical errors in our data
sets
10.2.2 Confidence Level/Accuracy Judgment
For radon measurements, accuracy is 10% of the measured value, with most of the
error due to uncertainty in the efficiency of the counting cell.
10.2.3 Measurement Error for Parameters
For radon measurements, accuracy is 10% of the measured value, with most of the
error due to uncertainty in the efficiency of the counting cell.
10.2.4 Additional Quality Assessments
None.
10.2.5 Data Verification by Data Center
Data was 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.
12. Application of the Data Set
The data can be used for estimation of soil gas exchange rates from 222Rn data
(or testing of soil gas exchange rates derived from models).
13. Future Modifications and Plans
None given.
14. Software
14.1 Software Description
Calculations of fluxes for radon used linear regression from programs like
Microsoft Excel and Kaleidograph.
14.2 Software Access
Software sold by Licor and Campbell was used with the IRGA and data loggers.
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 Radon activity 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
Comma separated ASCII files with text delimited by single quotes (�).
17. References
17.1 Platform/Sensor/Instrument/Data Processing Documentation
Not applicable.
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).
ONeill, K. P., J. W. Harden, S. E. Trumbore, H. Veldhuis, 1995. U S Geological
Survey Open File Report.
Harden, J. W., K. P. O'Neill, S. E. Trumbore, H. Veldhuis, and B. J. Stocks,
submitted. Accumulation and Turnover of carbon in soils of the BOREAS NSA 2.
Carbon balance in soils of a mature black spruce stand (BOREAS NSA OBS).
submitted for JGR Atmospheres special BOREAS issue.
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).
Stuiver, M. and R. Kra, 1993. Radiocarbon v. 35 No 1. Calibration Issue.
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).
Trumbore, S. E. and J. W. Harden, submitted. Accumulation and Turnover of carbon
in soils of the BOREAS NSA 1. Methods for determining soil C balance in surface
and deep soil. submitted for JGR Atmospheres special BOREAS issue.
Trumbore, S. E. Measurement of cosmogenic isotopes by accelerator mass
spectrometry: applications to soil science, p. 311-340 in Mass Spectrometry of
Soils, T. Boutton and S. Yamasaki, eds, Marcel Dekker (New York) (1996).
Verardo, D., Froelich, P.N. and McIntyre, A., 1990. Determination of organic
carbon and nitrogen in marine sediments using the Carlo-Erba-N!-1500 Analyzer.
Deep-Sea Research, Part A - Oceanographic Research Papers 37:157-165.
Davidson, E. A. and S. E. Trumbore. Gas diffusivity and production of CO2 in
deep soils of the eastern Amazon, Tellus. 47B: 550-565 (1995).
Mathieu, G. G. P. E. Biscaye, R. A. Lupton and D. E. Hammond, 1988. System for
measurement of 222Rn at low levels in natural waters. Heath Physics 55:989-992.
Stephens, B. B. and E. T. Sundquist, submitted. Measurements of soil surface gas
fluxes using closed chamber techniques. (contact authors for status - Stephens
is now a student at Scripps Institution of oceanography)
Winston, G. C., E. T. Sundquist, B. B. Stephens and S. E. Trumbore, submitted,
Winter CO2 fluxes in a boreal forest; submitted for JGR Atmospheres special
BOREAS issue.
17.3 Archive/DBMS Usage Documentation
None.
18. Glossary of Terms
None given.
19. List of Acronyms
AMS - Accelerator Mass Spectrometry
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: 14-Nov-1997
Last Updated: 05-Aug-1998
20.2 Document Review Date(s)
BORIS Review: 10-Jul-1998
Science Review:
20.3 Document
20.4 Citation
For soils data, the USGS open file reports (see references, 17.2) should be
cited. For interpretations, cite submitted JGR papers (see references, 17.2).
Other citations should refer to the BORIS data set.
20.5 Document Curator
20.6 Document URL
Keywords
14C, 13C, 222Rn, CO2, CH4, Flux, Soil gas concentration
TGB12_RadonActivity
08/20/98