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Investigation:

CD-06 (Richey / Victoria)

LBA Dataset ID:

CD06_C_ISOTOPES

Originator(s):

1. MAYORGA, E.
2. AUFDENKAMPE, A.K.
3. MASIELLO, C.A.
4. KRUSCHE, A.V.
      5. HEDGES, J.I.
6. QUAY, P.D.
7. RICHEY, J.E.
8. BROWN, T.A.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

Amazonian rivers were recently shown to outgas more than ten times the amount of carbon exported to the ocean in the form of total organic carbon or dissolved inorganic carbon1. High carbon dioxide concentrations in rivers originate largely from in situ respiration of organic carbon, but little agreement exists about the sources or turnover times of this carbon. Here we present results of an extensive survey of the carbon isotope composition (13C and 14C) of dissolved inorganic carbon and three size-fractions of organic carbon across the Amazonian river system. We find that respiration of contemporary organic matter (less than five years old) originating on land and near rivers is the dominant source of excess carbon dioxide that drives outgassing in medium to large rivers, although we find that bulk organic carbon fractions transported by these rivers range from tens to thousands of years in age.

Beginning Date:

1991-08-12

Ending Date:

2003-01-26

Metadata Last Updated on:

2012-09-21

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 CD-06 Isotopic Composition of Carbon Fractions, Amazon Basin River Water :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1120

Documentation/Other Supporting Documents:

LBA-ECO CD-06 Isotopic Composition of Carbon Fractions, Amazon Basin River Water :  http://daac.ornl.gov/LBA/guides/CD06_C_Isotopes.html

Citation Information - Other Details:

Mayorga, E., A.K. Aufdenkampe, C.A. Masiello, A.V. Krusche, J.I. Hedges, P.D. Quay, J.E. Richey, and T.A. Brown. 2012. LBA-ECO CD-06 Isotopic Composition of Carbon Fractions, Amazon Basin River Water. Data set. Available on-line [http://daac.ornl.gov ] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1120

Keywords - Theme:

Parameter Topic Term Source Sensor
CARBON BIOSPHERE TERRESTRIAL ECOSYSTEMS LABORATORY MASS SPECTROMETER
CARBON DIOXIDE TERRESTRIAL HYDROSPHERE SURFACE WATER FIELD INVESTIGATION IRGA (INFRARED GAS ANALYZER)
DISSOLVED SOLIDS TERRESTRIAL HYDROSPHERE SURFACE WATER LABORATORY CHN ANALYZER
ORGANIC MATTER BIOSPHERE TERRESTRIAL ECOSYSTEMS LABORATORY WEIGHING BALANCE

Uncontrolled Theme Keyword(s):  AMAZON , CARBON ISOTOPES, CARBON SOURCES, RIVER WATER

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
    -1.81700 -16.47200 -58.79800 -74.57200

Related Publication(s):

Mayorga, E., A.K. Aufdenkampe, Masiello, C.A., Krusche, A.V., Hedges, A.I., Quay P.D., Richey, J.E. and T.A. Brown. 2005. Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers. Nature 436: 538--541. doi:10.1038/nature03880

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are provided in four ASCII comma separated files.

File #1:Sample_site_descriptions.csv

File #2:Geochemical_property_means.csv

File #3:C_fraction_delta_values_ind_samples.csv

File #4:Mean_C_fraction_delta_values.csv



File #1

File name:,Sample_site_descriptions.csv

File date:,31-May_2012

Associated LME: ,CD06_C_Isotopes



Column,Column_heading,Units/format,Explanation

1,Site_category,,Sites are categorized based on proportion of their drainage area at elevations greater than 1000 m

2,River,,Name of the river sampled

3,Site_name,,Name given to the sampling location. A few sites represent aggregated data from distinct sites in relative proximity.

4,Latitude,degrees S,Sampling location: latitude in decimal degrees S

5,Longitude,degrees W,Sampling location: longitude in decimal degrees W

6,Area,km2,Site drainage area in square kilometers

7,Elev_site,m,Elevation at the sampling site in meters

8,Elev_basin_mean,m,Mean elevation of the site drainage area in meters

9,Elev_1000,%,Percent of the site drainage area with elevation greater than 1000 m



Sample data for File #1:

Site_category,River,Site_name,Latitude,Longitude,Area,Elev_site,Elev_basin_mean,Elev_1000

Lowland,Candeias,Candeias,8.766,63.708,13,200,77,179,0.2

Lowland,Azul,Azul,9.627,64.942,4,030,103,184,0

Lowland,Novo,Novo,14.172,59.742,150,295,314,0

Lowland,Guapore,Vila Bela,14.993,59.958,21,660,193,335,0

Lowland,Ji-Parana,JIP-5,8.147,62.787,73,410,69,246,0

Lowland,Ji-Parana,JIP-4,8.947,62.057,67,640,91,257,0

Lowland,Machadinho,MAC,9.507,62.047,2,970,198,198,0

Lowland,Ji-Parana,JIP-3,10.092,61.977,43,580,181,284,0

Lowland,Jaru,JARU,10.102,61.996,7,410,180,254,0

Lowland,Boa Vista,NS1 ,10.757,62.368,< 10,296,297,0

Lowland,Boa Vista,NS2,10.753,62.372,< 10,296,298,0

Lowland,Ji-Parana,JIP-2,10.937,61.957,29,770,192,293,0

Lowland,Urupa,URUPA,10.902,61.962,4,820,191,264,0

Lowland,Rolim de Moura,ROLIM,11.445,61.731,2,060,200,236,0

Lowland,Ji-Parana,JIP-1,11.452,61.463,19,170,200,325,0

Lowland,Comemoracao,COM-2,11.667,61.188,6,740,199,372,0



File #2

File name:,Geochemical_property_means.csv

File date:,31-May-12

Associated LME:,CD06_C_Isotopes



Column,Column_heading,Unit/format,Explanation

1,Site_category,,Sites are categorized based on proportion of the site drainage area at elevations greater than 1000 m

2,River,,River name

3,Site_name,,Sampling site name

4,Site_ID,,Each sampling site was assigned a unique numeric site ID

5,Temperature,degrees C,Mean water temperature reported in degrees Celsius

6,pH,,Mean river water pH

7,Alkalinity,ueq per L,Mean river water alkalinity either measured by Gran titration or estimated from temperature, DIC and pH; reported in microequivalents per liter (ueq per L)

8,FSS,mg per L,Concentration of fine suspended sediments reported in milligrams per liter of water

9,Perc_FPOC,%wt,Percent of fine suspended sediments composed of fine particular organic carbon calculated as column 8 divided by column 13 and reported in percent

10,CO2,ppm,Mean river water CO2 concentrations were either measured directly by headspace equilibration or estimated from temperature, pressure, pH, DIC, and alkalinity and reported in parts per million (ppm)

11,DIC,umol per L,Concentration of dissolved inorganic carbon reported in micromoles per liter (umol per L)

12,DOC,mg per L,Concentration of dissolved organic carbon reported in milligrams per liter (mg per L)

13,FPOC,mg per L,Concentration of dissolved fine particulate organic carbon reported in milligrams per liter (mg per L)

14,CPOC,mg per L,Concentration of dissolved coarse particulate organic carbon reported in milligrams per liter (mg per L)

,missing data is represented by -9999

,Mean geochemical properties were based on samples analyzed for carbon isotopes



Sample data for File #2:

Site_category,River,Site_name,Site_ID,Temperature,pH,Alkalinity,FSS,Perc_FPOC,CO2,DIC,DOC,FPOC,CPOC

Lowland,Candeias,Candeias,6,25.4,5.92,98,19.1,7.13,7,640,362,1.65,1.36,0.13

Lowland,Azul,Azul,7,25.1,5.94,77,14.7,9.91,5,723,275,0.69,1.46,-9999

Lowland,Novo,Novo,9,24.7,6.41,98,15.6,9.42,2,476,184,0.68,1.47,0.93

Lowland,Guapore,Vila Bela,10,20.9,6.53,410,14.4,7.83,7,837,681,3.41,1.13,0.19

Lowland,Ji-Parana,JIP-5,17,31.5,7.07,344,11.6,-9999,2,099,404,2.04,-9999,-9999

Lowland,Ji-Parana,JIP-4,18,30.1,7.13,205,7.6,-9999,1,063,236,2.57,-9999,-9999

Lowland,Machadinho,MAC,19,29.3,6.72,125,13.7,-9999,1,653,175,2.02,-9999,-9999

Lowland,Ji-Parana,JIP-3,20,30.1,7.39,243,17,-9999,692,263,4.38,-9999,-9999

Lowland,Jaru,JARU,21,29.6,7.45,532,14.4,-9999,1,312,570,4.75,-9999,-9999

Lowland,Boa Vista,NS1 ,22,25.9,6.31,594,9.2,-9999,10,300,-9999,5.98,-9999,-9999

Lowland,Boa Vista,NS2,23,25.7,6.6,694,6.7,-9999,7,100,-9999,4.36,-9999,-9999

Lowland,Ji-Parana,JIP-2,24,26.5,6.97,248,21.9,5.71,1,525,300,2.78,0.88,0.1

Lowland,Urupa,URUPA,25,28.3,6.97,703,47.7,-9999,3,193,797,8.43,-9999,-9999

Lowland,Rolim de Moura,ROLIM,26,29.6,7.44,-9999,26,-9999,-9999,-9999,2.68,-9999,-9999

Lowland,Ji-Parana,JIP-1,27,29.3,7.15,131,14.8,-9999,643,150,2.43,-9999,-9999

Lowland,Comemoracao,COM-2,28,25.2,6.25,39,20.7,9.6,1,346,85,2.49,1.12,0.18

Lowland,Comemoracao,COM-1,29,23.6,5.32,3,15,1.96,1,872,70,1.6,0.53,-9999

Lowland,Pimenta Bueno,PB-2,30,28.9,7.12,197,14,-9999,1,031,229,4.02,-9999,-9999







File #3:

File name:,C_fraction_delta_values_ind_samples.csv

File date:,1-Jun-12

Associated LME:,CD06_C_Isotopes



Column,Column_heading,Units/format,Explanation,,

1,Site_category,,Sites are categorized based on proportion of their drainage area at elevations greater than 1000 m

2,Site_ID,,Each sampling site was assigned a unique numeric site ID

3,Date,YYYYMMDD,Sample date

4,C_fraction,,Carbon fraction analyzed: DIC= dissolved inorganic carbon; CO2= carbon dioxide; DOC= dissolved organic carbon; FPOC= fine particulate organic carbon; CPOC= coarse particulate organic carbon. Analyses for CO2 fraction were calculated; all others were measured directly.

5,Delta_14C,per mil,Isotopic ratio of 14C to 12C: Delta (capital greek Delta) 14C data are reported as [[14C/12C ratio of the sample divided by 0.95 times the 14C/12C of the Oxalic Acid I standard, decay corrected to 1950] -1]*1000 (as defined in Stuiver and Pollach, 1977). A mass dependent 13C correction has been applied

6,delta_13C,per mil,Isotopic ratio of 13C to 12C: delta (lowercase greek delta) 13C data are reported as [[13C/12C ratio of the sample divided by the 13C/12C of the PeeDee Belemnite standard] -1]*1000, or the deviation in parts per thousand of the 13C/12C ratio of the standard from the 13C/12C of the PDB standard



,missing data represented by -9999



Sample data for File #3:

Site_category,Site_ID,Date,C_fraction,Delta_14C,delta_13C

Lowland,6,19960702,DIC,-9999,-19.3

Lowland,6,19960702,CO2,100,-20.6

Lowland,6,19960702,FPOC,136,-30.8

Lowland,6,19960702,CPOC,208,-29.3

Lowland,7,19960627,DIC,-9999,-19.4

Lowland,7,19960627,CO2,85,-20.8

Lowland,9,19960705,DIC,-9999,-13.2

Lowland,9,19960705,CO2,109,-16.8

Lowland,10,19960706,DIC,-9999,-21

Lowland,10,19960706,CO2,-145,-25.3

Lowland,10,19960706,DOC,271,-26.6

Lowland,10,19960706,FPOC,-18,-31.6

Lowland,17,20000920,DIC,-9999,-11.8

Lowland,17,20000920,CO2,91,-17.7

Lowland,18,20000913,DIC,-9999,-10.4

Lowland,18,20000913,CO2,106,-16.6

Lowland,19,20000913,DIC,-9999,-14.5





File #4:

File name,Mean_C_fraction_delta_values.csv

File date,31-May-12

Associated LME:,CD06_C_Isotopes



Column,Column_heading,Unit/format,Explanation

1,Site_category,,Sites are categorized based on proportion of their drainage area at elevations greater than 1000 m

2,Carbon_fraction,,Identification of the carbon fraction ( CO2- carbon dioxide;DIC- dissolved inorganic carbon; DOC- dissolved organic carbon; FPOC- fine particulate organic carbon and CPOC- coarse particulate organic carbon)

3,N,,Number of samples included in the calculation of the mean value

4,Delta_14C,per mil,Mean Delta 14C value for this carbon fraction and site category combination reported in parts per mil

5,Std_dev_D14C,per mil,Standard deviation of the mean Delta 14C value

6,delta_13C,per mil,Mean delta 13C value for this carbon fraction and site category combination reported in parts per mil

7,Std_dev_d13C,per mil,Standard deviation of the mean delta 13C value



,missing data are represented by -9999



Sample data for File #4:

Site_category,Carbon_fraction,N,Delta_14C,Std_dev_D14C,delta_13C,Std_dev_d13C

Mountain,CO2,14,-240,233,-9999,-9999

Mixed,CO2,11,-14,99,-9999,-9999

Lowland,CO2,43,89,44,-9999,-9999

Carbonate-free lowland,CO2,38,98,20,-9999,-9999

Mountain,DIC,14,-9999,-9999,-4.9,2.7

Mixed,DIC,11,-9999,-9999,-14.2,2.9

Lowland,DIC,43,-9999,-9999,-17,5.9

Carbonate-free lowland,DIC,38,-9999,-9999,-17.1,6.2

Mountain,DOC,6,94,176,26,3

Mixed,DOC,9,196,59,-29,0.6

Lowland,DOC,15,177,64,-29,0.9

Carbonate-free lowland,DOC,11,175,67,-29.1,0.7

Mountain,FPOC,8,-202,198,-25.7,1.7

Mixed,FPOC,10,-135,141,-28.2,0.9

Lowland,FPOC,10,90,55,-29.9,1.8

Carbonate-free lowland,FPOC,6,129,10,-29.2,2.1

Mountain,CPOC,9,-39,146,-27,1.6

Mixed,CPOC,9,-124,66,-27.7,0.9

Data Application and Derivation:

Isotopic calculation of CO2 gas in equilibrium with DIC. DIC is composed

of dissolved carbonate species (H2CO3(aq), HCO3(aq), and CO3(aq)) in

temperature- and pH-dependent equilibrium with one another. Isotopic

fractionation occurs during conversion from one species to another (Clark and Fritz 1997)and dissolution of CO2 gas; CO2 gas is hereafter referred to as simply CO2. delta 13C of CO2 gas in equilibrium with DIC is calculated from measured d13C-DIC and pH, and from temperature-dependent isotopic equilibrium fractionations between CO2 and DIC species (Clark and Fritz 1997, Zhang et al 1995). pH can vary dramatically in a large basin and is largely a function of weathering lithologies. Delta 14C is defined to be insensitive to mass-dependent fractionation(Stuiver and Pollach, 1977); as a result Delta 14C-CO2 equals Delta 14C-DIC. Although a focus on isotopes of CO2 instead of DIC is unconventional, it yields more straightforward assessments of the impact of respiration and air--water gas exchange on DIC across geochemically diverse rivers.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Absolute Delta 14C and delta 13C analysis errors (1 sigma) are typically less than 6 per mil and less than 0.2 per mil, respectively.



Radiocarbon trends in atmospheric CO2.

Measurements from Schauinsland Station, Germany, were used to characterize atmospheric D14C-CO2 from 1991 to 2003 (Levin and Hesshaimer 2000, Levin and Kromer 2004). The uncharacterized effect of seasonal and short-term

atmospheric variability is minimized by comparing river 14C only against timeweighted annual means (Levin and Kromer 2004). A constant plus 8 per mil offset was added to Schauinsland annual means to account for a 5 per mil depletion from regional fossil-fuel emissions at Schauinsland relative to the well-mixed, mid-latitude European troposphere (Jungfraujoch site, Levin and Kromer 2004), and approximately 3 per mil further depletion at the midlatitude troposphere relative to tropical South America (Levin and Hesshaimer 2000,Randerson et al. 2002). Atmospheric Delta 14C CO2 composition within the Amazon basin is unknown, but seasonal and regional variability may be as large as 10 per mil (Randerston et al. 2002). Riverine Delta 14C values within 5 per mil of our estimated atmospheric annual average for the sampling year probably represent carbon turnover times of one year or less. Mid-1990s tropospheric CO2 can be characterized by a partial pressure (pCO2 ) of 370 p.p.m. and delta 13C composition of 28 per ml (Clark and Fritz 1997, Levin and Hesshaimer 2000, Randerson et al. 2002).

Process Description:

Data Acquisition Materials and Methods:

Sample collection and analysis.



Samples analysed for 14C-DIC were collected between 1991 and 2003, whereas organic-carbon 14C samples are from 1995 through 1996. All samples were preserved with mercuric chloride immediately after collection at mid-depth from the deepest section of the channel. DIC samples were prepared as described in Quay et al. (1992) and stored in tightly capped glass bottles for up to 24 months; in the lab, the top half of the bottle was drawn into a vacuum line (eliminating particles) and stripped of CO2 after acidification (Quay et al 1992).



CPOC (63 to 2,000 um) was isolated either by sieving or with a plankton net,

FPOC (0.1 to 63 um) by tangential flow microfiltration, and DOC (1,000 atomic

mass units to 0.1 um) by tangential flow ultrafiltration(Hedges et al 2000). Final concentration and drying was achieved by centrifugal evaporation or freeze drying, and the dried powder stored in the dark at ambient temperature for up to 6 yr (Hedges et al 2000). Organic samples were combusted as in (Quay et al 1992). Cryogenically purified CO2 from organic carbon and DIC was analysed for stable isotope and radiocarbon by dual-inlet Isotope Ratio Mass Spectrometry and Accelerator Mass Spectrometry (AMS)(Vogel et al. 1987), respectively; more than 90 percent of 14C analyses were carried out at the Lawrence Livermore National Laboratory Center for Accelerator Mass Spectrometry, and the rest at the University of Arizona AMS Laboratory. CO2 extracted from DIC was stored in sealed glass ampoules for up to 8 yr. 13C is reported in delta 13C notation versus the PDB standard (Clark and Fritz 1997). Radiocarbon values are reported as age-corrected Delta 14C adjusted for sample delta 13C (Stuiver and Polach 1977); carbon is defined as modern when it originates after 1890 (Stuiver and Polach 1977).



Isotopes for all carbon fractions were not always analysed at each site. Additional analyses include pH, major ions, alkalinity and total carbon fraction concentrations. Major ions were quantified by ion chromatography. Alkalinity was measured by Gran titration, or estimated from temperature, pH and DIC when not measured. CO2 concentrations were either measured directly by headspace equilibration or estimated from temperature, pressure, pH, DIC, and alkalinity.





Radiocarbon trends in atmospheric CO2.

Measurements from Schauinsland Station, Germany, were used to characterize atmospheric D14C-CO2 from 1991 to 2003 (Levin and Hesshaimer 2000, Levin and Kromer 2004). The uncharacterized effect of seasonal and short-term

atmospheric variability is minimized by comparing river 14C only against timeweighted annual means (Levin and Kromer 2004). A constant plus 8 per mil offset was added to Schauinsland annual means to account for a 5 per mil depletion from regional fossil-fuel emissions at Schauinsland relative to the well-mixed, mid-latitude European troposphere (Jungfraujoch site, Levin and Kromer 2004), and approximately 3 per mil further depletion at the midlatitude troposphere relative to tropical South America (Levin and Hesshaimer 2000,Randerson et al. 2002). Atmospheric Delta 14C CO2 composition within the Amazon basin is unknown, but seasonal and regional variability may be as large as 10 per mil (Randerston et al. 2002). Riverine Delta 14C values within 5 per mil of our estimated atmospheric annual average for the sampling year probably represent carbon turnover times of one year or less. Mid-1990s tropospheric CO2 can be characterized by a partial pressure (pCO2 ) of 370 p.p.m. and delta 13C composition of 28 per ml (Clark and Fritz 1997, Levin and Hesshaimer 2000, Randerson et al. 2002).

References:

Clark, I. & Fritz, P. 1997. Environmental Isotopes in Hydrogeology (Lewis Publishers, Boca Raton.



Hedges, J. I. et al. 2000. Organic matter in Bolivian tributaries of the Amazon River: A comparison to the lower mainstem. Limnol. Oceanogr. 45, 1449--1466.



Levin, I. & Hesshaimer, V. 2000. Radiocarbon--A unique tracer of global carbon cycle dynamics. Radiocarbon 42, 69--80.



Levin, I. & Kromer, B. 2004. The tropospheric 14CO2 level in mid-latitudes of the Northern Hemisphere (1959--2003). Radiocarbon 46, 1261--1272.



Quay, P. D. et al. 1992. Carbon cycling in the Amazon River: Implications from the 13C compositions of particles and solutes. Limnol. Oceanogr. 37, 857--871.



Randerson, J. T., Enting, I. G., Schuur, E. A. G., Caldeira, K. & Fung, I. Y.2002. Seasonal and latitudinal variability of troposphere Delta 14CO2: Post bomb contributions from fossil fuels, oceans, the stratosphere, and the terrestrial biosphere. Glob. Biogeochem. Cycles 16, doi:10.1029/2002GB001876.



Stuiver, M. & Polach, H. A. 1977.Discussion: reporting of 14C data. Radiocarbon 19, 355--363.



Vogel, J. S., Nelson, D. E. & Southon, J. R. 1987. 14C background levels in an accelerator mass spectrometry system. Radiocarbon 29, 323--333.



Zhang, J., Quay, P. D. & Wilbur, D. O. 1995. Carbon isotope fractionation during

gas-water exchange and dissolution of CO2. Geochim. Cosmochim. Acta 59,

107--114.

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