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LBA-ECO TG-04 Radon Activity at Forested and Pasture Sites, Para, Brazil: 2000-2004

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Revision date: July 22, 2015

Summary:

This data set provides measurements of Radon-222 activity in air within and above the vegetation canopy at three flux tower sites in Para, Brazil: the km 67 forested site located in undisturbed old-growth (primary) forest and the km 83 logged forest site, both in Tapajos National Forest, and the km 77 pasture tower site on BR-163 just south of the city of Santarem. Measurements were made over various intervals from 2000 to 2004.

Continuous Rn-222 activity profiles within and above the forest canopy were measured with detector array systems of eight or more flow-through detectors based on a pulse-ionization Rn counting air chamber controlled by custom software.

There are 16 data files in comma-delimited (.csv) format with this data set.

Data Citation:

Cite this data set as follows:

Martens, C.S., O.L.L. de Moraes, P.M. Crill, H.P. Mendlovitz, and J.M. Moura. 2015. LBA-ECO TG-04 Radon Activity at Forested and Pasture Sites, Para, Brazil: 2000-2004. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/1276

Implementation of the LBA Data and Publication Policy by Data Users:

The LBA Data and Publication Policy [http://daac.ornl.gov/LBA/lba_data_policy.html] is in effect for a period of five (5) years from the date of archiving and should be followed by data users who have obtained LBA data sets from the ORNL DAAC. Users who download LBA data in the five years after data have been archived must contact the investigators who collected the data, per provisions 6 and 7 in the Policy.

This data set was archived in March 2015. Users who download the data between March 2015 and February 2020 must comply with the LBA Data and Publication Policy.

Data users should use the investigator contact information in this document to communicate with the data provider. Alternatively, the LBA Web Site [http://lba.inpa.gov.br/lba/] in Brazil will have current contact information.

Data users should use the Data Set Citation and other applicable references provided in this document to acknowledge use of the data.

Table of Contents:

Project: LBA (Large-Scale Biosphere-Atmosphere Experiment in the Amazon)

Activity: LBA-ECO

LBA Science Component: Trace Gas and Aerosol Fluxes

Team ID: TG-04 (Martens / Moraes)

The investigators were Martens, Christopher S.; Moraes, Osvaldo Luiz Leal de; Crill, Patrick Michael; Mendlovitz, Howard P.; Moura, Jose Mauro; Shay, Tom; Saleska, Scott R. and Wofsy, Steven C. You may contact Martens, Christopher S. (cmartens@email.unc.edu) and Mendlovitz, Howard P. (mendlovitz@unc.edu).

LBA Data Set Inventory ID: TG04_Radon_Flux

This data set provides measurements of Radon-222 activity in air within and above the vegetation canopy at three flux tower sites in Para, BRazil: the km 67 forested site located in undisturbed old-growth (primary) forest and the km 83 logged forest site, both in Tapajos National Forest, and the km 77 pasture tower site on BR-163 just south of the city of Santarem. Measurements were made over various intervals from 2000 to 2004.

Continuous Rn-222 activity profiles within and above the forest canopy were measured with detector array systems of eight or more flow-through detectors based on a pulse-ionization Rn counting air chamber controlled by custom software.

 

Related Data Sets:

2. Data Characteristics:

Data are provided in 16 comma-delimited (.csv) files organized by study site. Data provide the activity of radon recorded at various heights above the ground, reported in milliBecquerels per meter cubed (mBq per m3).

The measurement year is provided in the file names. For the years where detectors were added and redistributed (km 67 and km 83 sites) two files are available.

Table 1. Data File Names

File Name Dates (YYYYMMDD) Heights (sampling heights above ground  provided in centimeters (cm)
TG04_Radon_67km_2000.csv 20000423-20001231 30,100, 300, 1070, 3200, 3700, 4720, and 6100
TG04_Radon_67km_2001.csv 20010105-20011231 30,100, 300, 1070, 3200, 3700, 4720, and 6100
TG04_Radon_67km_2002.csv 20020101-20021227 30,100, 300, 1070, 3200, 3700, 4720, and 6100
TG04_Radon_67km_20030101_20031022.csv20030101-20031022 30,100, 300, 1070, 3200, 3700, 4720, and 6100
TG04_Radon_67km_20031029_20031231.csv 20031029-20031231 10, 35, 91, 150, 305, 600, 1042, 1957, 2871, 3941, 5005, 6224
TG04_Radon_67km_2004.csv20040101-20041206 10, 35, 91, 150, 305, 600, 1042, 1957, 2871, 3941, 5005, and 6224
TG04_Radon_77km_2001.csv 20010101-20011231 30, 100, 300, 1000, 1150
TG04_Radon_77km_2002.csv 20020103-20021231 30, 100, 300, 1150
TG04_Radon_77km_2003.csv 20030101-20031231 30, 100, 300, 1150
TG04_Radon_77km_2004.csv 20040101-20041231 30, 100, 300, 1150
TG04_Radon_83km_2000.csv 20000501-20001231 30, 100, 300, 1070, 3500, 4000, 4500, and 6400
TG04_Radon_83km_20010101_20010604.csv 20010101-20010604 30,100, 300, 1070, 3500, 4000, 4500, and 6400
TG04_Radon_83km_20010604_20011231.csv 20010604-20011231 10, 35, 70, 150, 300, 600, 1080, 2000, 3500, 3975, 5000, and 6440
TG04_Radon_83km_2002.csv 20020101-20021231 10, 35, 70, 150, 300, 600, 1080, 2000, 3500, 3975, 5000, and 6440
TG04_Radon_83km_2003.csv 20030101-20031231 10, 35, 70, 150, 300, 600, 1080, 2000, 3500, 3975, 5000, and 6440
TG04_Radon_83km_2004.csv20040101-20041231 10, 35, 70, 150, 300, 600, 1080, 2000, 3500, 3975, 5000, and 6440

Table 2. Example Data File Structure (Radon_67km_2000.csv)

Missing data are indicated by -9999.

COLUMN COLUMN HEADING Units/format Description
1 Year YYYY Year in which samples were collected
2DateYYYYMMDD Sampling date in local time
3TimeHH:MM:SS Start of the 15 minute sampling period in local time (local time= GMT-4)
4Rn_30mBq per m3 Activity of radon at 0.3 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
5Rn_100mBq per m3 Activity of radon at 1.0 meter above the ground reported in milliBecquerels per meter cubed (mBq per m3)
6Rn_300mBq per m3 Activity of radon at 3.0 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
7Rn_1070mBq per m3 Activity of radon at 10.7 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
8Rn_3200mBq per m3 Activity of radon at 32.0 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
9Rn_3700mBq per m3 Activity of radon at 37.0 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
10Rn_4720mBq per m3 Activity of radon at 47.2 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
11Rn_6100mBq per m3 Activity of radon at 61.0 meters above the ground reported in milliBecquerels per meter cubed (mBq per m3)
 

Example Data Records (Radon_67km_2000.csv)

Year,Date,Time,Rn_30,Rn_100,Rn_300,Rn_1070,Rn_3200,Rn_3700,Rn_4720,Rn_6100
2000,20000423,13:45:00,13,-9999,-9999,-9999,-9999,-9999,-9999,-9999
2000,20000423,14:00:00,-9999,-9999,-9999,-9999,-9999,-9999,-9999,-9999
2000,20000423,14:15:00,-9999,-9999,-9999,-9999,-9999,-9999,-9999,-9999
...
2000,20001231,22:30:00,12.139,12.608,9.06,7.998,7.246,2.773,2.887,2.731
2000,20001231,22:45:00,11.928,10.662,7.534,8.457,7.407,4.438,2.17,2.464
2000,20001231,23:00:00,13.687,11.69,8.39,7.538,7.567,3.583,2.306,3.188

Site boundaries: (All latitude and longitude given in decimal degrees)

Site (Region) Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost LatitudeDatum
Para Western (Santarem) - km 67 Primary Forest Tower Site -54.959 -54.959 -2.857 -2.857WGS-84
Para Western (Santarem) - km 77 Pasture Tower Site -54.88850 -54.88850 -3.02020 -3.02020WGS-84
Para Western (Santarem) - km 83 Logged Forest Tower Site -54.97070 -54.97070 -3.01700 -3.01700WGS-84

Time period: The data set covers the period 2000/01/01 to 2004/12/31.

Temporal Resolution: Continuous.

Platform/Sensor/Parameters measured include:

3. Data Application and Derivation:

Radon-222 is used as a transport tracer to quantify mass transport processes between forest canopies and the atmosphere. Gas exchange rates yield mean canopy air residence times ranging from minutes during turbulent daytime hours to greater than 12 hours during calm nights. Radon is an effective tracer for net ecosystem exchange of CO2 (CO2 NEE) during calm, nighttime hours when eddy covariance-based NEE measurements are less certain because of low atmospheric turbulence (Martens et al., 2004). Flux of Rn-222 from the soil is needed for these calculations but  is not provided with this data set.

Initial results, from month-long periods at the end of the wet season (June-July) and the end of the dry season (Nov-Dec) in 2001, demonstrate the potential of new radon measurement instruments and methods to quantify mass transport processes between forest canopies and the atmosphere.

4. Quality Assessment:

The detectors for the continuous-sampling flowthrough system were calibrated regularly using a Ra-226 RNC Rn source, serial number 106. This source was commercially produced by Pylon Electronic Inc. (Ottawa, Ontario, Canada). The calibration was a two-step procedure. First, a Rn-free gas was introduced to the detector at 1 L per min using a mass flow controller to ensure accurate and precise delivery. This allowed us to correct for background noise within each detector. Then the known Rn source was added in series to calculate the sensitivity calibration coefficient. Both steps were run for a minimum of 24 h to obtain adequate counting statistics. In addition, the system is checked monthly with a field calibration. During this 2-day period, all detectors were valved to the same atmospheric gas. This procedure allowed the investigators to check for detector stability and make necessary corrections.

The flow-through detectors proved to have a precision of better than plus or minus 0.74 Bq per m3 [95% confidence limits,based on a bootstrap analysis (Efron and Gong, 1983)] of Rn activity based on binning 15 min of counts.

5. Data Acquisition Materials and Methods:

Site Descriptions

Measurements were made from the three eddy flux towers located in and near the Tapajos National Forest, Para, Brazil. The towers are identified by the nearest kilometer marker on the BR 163 highway which runs south from the city of Santarem to the city of Cuiba. Annual mean temperature in the area is 25 degrees C (Silver et al. 2000). The rainy season extends from late December or early January through June. The duration of the rainy period varies from year to year. Vegetation at the forested sites is evergreen, mature tropical forest with a total biomass of about 372 Mg per ha (Keller et al. 2002). The sites are located on an old, nearly flat, erosional remnant plateau with well-drained soils.

km 83 tower

This tower is located within the Tapajos National Forest. The site was selectively logged starting in September 2001. Forest extended 5 km to the east, 8 km to the south, and 40 km to the north of the tower before reaching pasture. The site is on a flat plateau (the planalto) that extended many kilometers to the north, south, and east. Forest continued 8 km west to the edge of the planalto before dropping to the Tapajos River 14 km from the tower. The total relief within 1 to 2 km of the tower was approximately 10 m, with occasional 10 to 30-m deep stream gullies farther from the tower.

km 77 tower

The agricultural site flux tower stands in an approximately 500-ha field surrounded by primary and secondary forest with a 40-m tall average canopy height. The tower is 25 km from the 15-km wide Tapajos River on terrain that slopes at about 4.81 from west to east. To the east, a small spring-fed lake 460 m from the tower, surrounded by small trees and shrubs, lies at the bottom of the slope (about 39m below the tower level). The soil type is yellow latosol (Raimundo Cosme, EMBRAPA, personal communication). When the field was used for grazing, the field was planted in a commonly used grass species, Brachiara brizantha. When in pasture, the cattle density was approximately one animal per hectare. In the process of introducing upland rice, the pasture was burned on November 14, 2001, and over the next few days the field was plowed.

km 67 Tower

The site is located in the Tapajos National Forest accessed by an entrance road at kilometer 67 along the Santarem-Cuiaba Highway (BR-163). The eddy-flux tower was installed 1 km east of the access road. Forest is undisturbed old-growth (primary) forest.

Rn-222 Activity Profile Measurements

Continuous Rn-222 activity profiles within and above the forest canopy were measured with detector array systems of four to eight or more flow-through detectors controlled by custom software on portable computers. The same computers were also used for data storage. The flow-through detectors had a precision of better than plus or minus 0.74 Bq per m3 [95% confidence limits, based on a bootstrap analysis (Efron and Gong, 1983)] of Rn activity based on binning 15 minutes of counts. The detector arrays included a nafion tubing water removal system that utilized recirculated pump air to exhaust water vapor removed from ambient air arriving from the sampling ports on the tower (Martens et al., 2004).

The flow-through detector is based on a pulse-ionization Rn counting air chamber.  The counting chamber consists of a large sealed aluminum vessel (approximately 20 L active sample volume) with coaxially mounted ion collection electrode. The air sample to be analyzed is introduced into the chamber at flow rates (approximately 1 L per min) consistent with an adequate sample exchange rate. Up to eight counting chambers may be connected in a single detector system.

Eight detectors were installed at the km 67 tower in April 2000 at heights between 0.3 and 61 meters above the ground. In October 2003 four additional detectors were added and the original detectors redistributed to cover the profile between 0.1 m and 62.24 meters above the ground. Similarly, at the km 83 tower, eight detectors were installed in May 2000 and four additional detectors were added on June 4, 2001 with the original detectors redistributed on the same date. At the km 77 tower there were four detectors installed on January 1, 2001. The detector originally placed at 10-m above the ground was relocated to 11.5-m above ground on December 12, 2001, but no additional detectors were added.

6. Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Data Archive Center:

Contact for Data Center Access Information:

E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952

7. References:

Efron B, Gong G (1983) A leisurely look at the bootstrap, the jackknife, and cross-validation. American Statistician, 37, 36-48.

Keller M, Silva H, Crill PM et al. (2002) Automated chamber measurements of soil–atmosphere carbon dioxide flux in undisturbed forest at the Tapajos National Forest, Brazil. Eos Transactions of the American Geophysical Union, 83, Fall Meet. Suppl., Abstract B22A-0734.

Martens, C. S., Shay, T., Mendlovitz, H. P., Matross, D. M., Saleska, S. R.,Wofsy, S. C.,Woodward,W. S., Menton, M. C., de Moura, J. M. S., Crill, P. M., de Moraes, O. L. L., and Lima, R. L. (2004) Radon fluxes in tropical forest ecosystems of Brazilian Amazonia: night-time CO2 net ecosystem exchange derived from radon and eddy covariance methods, Global Change Biol., 10, 618– 629, doi: 10.1111/j.1529-8817.2003.00764.

Silver WL, Neff J, McGroddy M et al. (2000) Effects of soil texture on belowground carbon and nutrient storage in a lowland Amazonian forest ecosystem. Ecosystems, 3, 193–209.