BOREAS TGB-12 ^222^Rn 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 ^222^Rn 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 ^222^Rn Activity data over the NSA

1.2 Data Set Introduction

This dataset contains seasonal variations in the ^222^Rn 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

^222^Rn Activity and soil depth were measured over the BOReal Ecosystem
Atmosphere Study (BOREAS) Northern Study Area (NSA).

1.5 Discussion

Carbon inventories together with ^14^C 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 CO~2~ (which will reflect the ^14^C 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.

^222^Rn 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 ^222^Rn Activity.

4.1.4 Key Variables

The key variables measured were ^222^Rn 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 ^226^Ra 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 ^222^Rn 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
^222^Rn 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 (Î).

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

^14^C, ^13^C, ^222^Rn, CO~2~, CH~4~, Flux, Soil gas concentration