emerging perspectives on continental-scale riverine carbon fluxes david butman, yale university

EMERGING PERSPECTIVES ON

CONTINENTAL-SCALE

RIVERINE CARBON FLUXES

David Butman, Yale UniversityEdward G. Stets, U.S. Geological SurveyPeter Raymond, Yale UniversityRobert G. Striegl, U.S. Geological Survey

Acknowledgements -

NASA Earth and Space Science Fellowship

NSF-Ecosystems CAREER

Yale Center for Earth Observation

Christopher Zappa, Tom Bott, Jody Potter, Patrick Mulholland and William McDowell (Gas Transfer Meta-Analysis), Charlie Crawford, Kathleen Johnson, Cory McDonald.

AQUATIC CARBON CYCLINGAQUATIC CARBON CYCLING

CO2 IC OC

Stream flow

CO2 IC OC

UpstreamTerrestrialHyporheic

DownstreamorCoastal

IC – Inorganic carbonOC – Organic carbon


CO2 CO2

CO2 IC OC

Stream flow

CO2 IC OC

IC OCCO2CO2


DownstreamorCoastal


Sedimentation


CO2 IC OC

Stream flow

CO2 IC OC


DownstreamorCoastal


CO2

“CO2 Flux”“Lateral Flux”

Sedimentation

Water quality and streamflow data–• USGS National Water Information System (NWIS).

• National Stream Quality Accounting Network (NASQAN).

DATA SOURCES & TERMINOLOGYDATA SOURCES & TERMINOLOGY

Carbon fractions –

• Inorganic carbon (IC) and CO2

• Calculated from Alkalinity, temperature, pH

• Assume alkalinity arises from ΣCO2

• Assume particulate fraction of alkalinity is negligible

• Organic carbon (OC).

• Total organic carbon (TOC) – unfiltered

• Dissolved organic carbon (DOC) - filtered

Inorganic carb(g C m-2 yr-1)

>

4

<

No LATERAL CARBON FLUXESLATERAL CARBON FLUXES

COCO2 2 FLUX FROM STREAMS FLUX FROM STREAMS

otal lux: .7 Tg C yr-1

Tota (Tg

ICTOCCO2

RIVERINE C FLUX IN PERSPECTIVERIVERINE C FLUX IN PERSPECTIVE

USGS Load Estimator (LOADEST)-

1. Calibration data.

2. Multiple regression.

3. Calculate daily loads.

4. Aggregate into annual fluxes.

DateStream Flow (cfs)

TOC (mg L-1)

04/24/2008 17,100 5.04

05/20/2008 12,500 4.45

06/11/2008 5,390 4.69

07/10/2008 6,520 6.23

08/05/2008 6,520 4.69

08/20/2008 8,290 6.87

09/17/2008 10,600 7.31

10/14/2008 8,270 6.2

12/23/2008 37,300 7.7

01/15/2009 25,600 5.44

02/05/2009 13,300 3.92

02/17/2009 13,500 16.99

FLUX CALCULATIONSFLUX CALCULATIONS




)cos()sin(lnlnln 432

210 timeatimeaQaQaaLOAD



Relationship between load and stream flow

Seasonal variability







Daily TOC loads (x106 g d-1)

Jan-08 Jul-08 Jan-09 Jul-09 0

2000

4000

6000







2008 20090.0

0.1

0.2

Annual TOC loads (Tg C yr-1)


1950 1970 1990 20100

200

400

600

800

1000 TOC (n = 5,126; 151 sites)

IC (n = 4,552; 161 sites)

DOC (n = 3,121; 144 sites)

DATABASE FEATURESDATABASE FEATURES

Observationsper year


TOC

IC

DOC

Weighted bydrainage area


Drainage Area Discharge0

20

40

60

80

100

IC TOC DOC

Percent includedin lateral flux database

0

10

20

30

40

50

IC TOC

SUMMARY OF FINDINGSSUMMARY OF FINDINGS

Observed Corrected fordrainage area

Corrected fordischarge

Lateral fluxTg C yr-1

28 32 34

11

910

Total =37

Total =42

Total =45

COMPARISON WITH OTHER STUDIESCOMPARISON WITH OTHER STUDIES

0 5 10 15 20 25 30

This study

Mulholland 1982

Boyer et al. (In prep.)

Meybeck 1981

Schlesinger and Melack 1982

TOC Flux from Conterminous U.S. (Tg C yr-1)

† - Disaggregated by watershed area.

†

§ - Disaggregated by biome type.

§

§

Inorganic carbon yield(g C m-2 yr-1)

Dissolved organic carbon yield(g C m-2 yr-1)

> 7

4 – 72 - 4

< 2

No data

> 4

2 – 40.8 – 2

< 0.8

No data

REGIONAL PATTERNSREGIONAL PATTERNS

Carbon yieldg C m-2 yr-1

St Law

renc

e

Miss

issipp

i

South

west

North

east

North

west

Easte

rn G

ulf

Wes

tern

Gulf

South

east

Red

Colora

do0

2

4

6

8

Entire

U.S

.

IC

TOC

Calculating COCalculating CO22 flux flux

• Stream surface area• CO2 concentrations• Transfer velocity

Flux = stream surface area * ([CO2]water - [CO2]air)* k

High Resolution NHDPlus data•Inventory of streams•Stream order•Modeled discharge•Modeled slope•Modeled velocity

Stream areaStream area

Use modeled discharge to calculate stream width.

Sum all stream segments to obtain total stream area.


ln discharge

n = 1,026

Verification data from USGS streamgaging stations

Raymond et al. In Prep.

Use modeled discharge to calculate stream width.

Sum all stream segments to obtain total stream area.


ln discharge

n = 1,026

Verification data from USGS streamgaging stations

Raymond et al. In Prep.

Surface Area of Streams: 40,560 km2

~1/2 of Lake Superior (US)~Costa Rica

•Calculated from alkalinity, temperature, and pH

•4,200 sites

•440,000 observations

COCO22 concentrations concentrations

COCO22 concentrations concentrations

Northern

K600 (m d-1) = 2841(SV) + 2.025

S= Slope ; V = Velocity

Gas transfer velocityGas transfer velocity

Raymond et al. in prep

Gas transfer velocityGas transfer velocity

Very high k in low-order Western streams.

Total Flux: 96.7 ± 32 Tg C yr-1

Total COTotal CO22 flux from streams flux from streams

Flux = stream surface area * ([CO2]water - [CO2]air)* k

Regional CORegional CO22 yield yield

CO2 yieldg C m-2 yr-1

Centra

lGulf

North

ern

Midw

est

Wes

t

South

west

0

10

20

Entire

US

LATERAL VERSUS COLATERAL VERSUS CO22 FLUXES FLUXES

Lateral flux

CO2

CO2

CO2

CO2

CO2

CO2

CO2 flux• Diffuse• Dominated by low-order streams.

Lateral flux• Focused• Top 10 streams carry

• 75% of IC flux.• 60% of TOC flux.


CO2 and lateral fluxes• Correlated with precipitation and

runoff.• Water discharge.

• Carbon delivery from terrestrial environment.

• In-stream carbon transformations.

CO2

r2 = 0.86

TOCr = 0.72

g C

m-2 y

r-1

Runoff (mm yr-1)

Total carbon flux in riversTotal carbon flux in rivers

Total flux (Tg C yr-1)

IC 34TOC 11CO2 97

Total 142

142 Tg C yr-1


Yield (g C m-2 yr-1)

IC 4.0TOC 1.9CO2 14.9

Total 20.8

20.8 g C m-2 yr-1

Carbon fluxes in contextCarbon fluxes in context

>142 Tg C yr-1

Stream flow

45 Tg C yr-1

97 Tg C yr-1

“CO2 Flux”“Lateral Flux”

Sedimentation

?

Terrestrial and aquatic carbon fluxTerrestrial and aquatic carbon flux

NEP (g C m-2 yr-1)

Grasslands 24 ± 14 Zhang et al. 2011

Total flux Rivers & Streams

20.8 This study

Predictor of Basin Flux Slope r2

Stream Surface Area %1 0.72 0.78

Average Annual Precipitation2

23.1 0.86

% Forested Land3 0.56 0.64

• Precipitation controls the regional differences in CO2 flux

• Short-term: flushing of soil CO2

• Long-term: geomorphology of the density of stream networks (stream surface area).



Lateral flux

CO2

CO2

CO2

CO2

CO2

CO2

CO2 flux• Dominated by fluxes in small-order

streams.• Strong correlation with precipitation.

Carbonate Weathering

Soil Respiration

Acidity:Precipitation /

Mining

Allochthonous DOM Respiration

Wetlands / Riparian

Vegetation

• The dominant source of pCO2 will depend on scale

• Headwater systems will show terrestrial respiration• Large river systems will incorporate internal and external

sources.

Contribution of Soil CO2 to River Efflux

• Soil Water pCO2 20,000 – 30,000 ppm• Derived land surface run-off from USGS – Waterwatch –

Wolcock et al. – in prep.• Total US discharge 1722 km3

– Amazon discharge ~ 5000 km3

Region Basin Area thousand km2

Predicted q (m)

Predicted Max Total Flux Tg C

Predicted CO2

Evasion Flux Tg C

Max % of CO2 efflux

exported laterally (Soil)

Central 1020 0.36 6.6 23.3 28.1%

Northern 909 0.39 6.3 15.5 40.8%

Midwest 1965 0.06 2.2 15.3 14.4%

Gulf 1425 0.32 1.72 26.8 30.5%

West 1788 0.22 8.1 12.6 56.2%

Southwest 722 0.02 7.1 3.3 7.0%

Total US 7828 0.22 31.0 96.7 32.1%

Contribution of Soil CO2 to River Efflux


Yield (g C m-2 yr-1)IC 3.9TOC 2.8CO2 25.5

Total 32.2

Stream w = e(0.42(lnQ)+2.55) Raymond et al. in prep

Stream Surface Area:

F(g C yr-1) = ([CO2]water - [CO2]air)* k * Surface Area

1026 sites


North

east

South

east

Easte

rn G

ulf

Wes

tern

Gulf

Miss

issipp

i

St Law

renc

eRed

Colora

do

South

west

North

west

0

2

4

6

8

All

Carbon yieldg C m-2 yr-1


0

10

20

30

40

50

IC POC DOC

Observed Corrected fordrainage area

Corrected fordischarge

Lateral fluxTg C yr-1

28 32

7

34

38

36 3

Gulf

Wes

t

Centra

l

North

Midw

est

South

west

0

10

20

Entire

US


CO2 yieldg C m-2 yr-1


Observationsper year

Willamette River(at Salem, OR)

Illinois River(at Peoria, IL)(at Valley City, IL)

Schuylkill River(at Philadelphia, PA)

Acknowledgements –

Whitney Broussard (U of Louisiana, Lafayette)

Thor Smith (USGS Vermont / New Hampshire)

Valerie Kelly (USGS Oregon)

Evan Hornig (USGS Austin, TX)

Kate Halm (USGS Colorado)

Sources of data and methods of analysis –

SourcesWater quality -• Clarke (1924) compilation of Dole & Stabler survey (USGS).

• U.S. Geological Survey (National Water Information System).

• Illinois State Water Survey.• Illinois Environmental Protection Agency.• Philadelphia Water Department.

Stream discharge –• U.S. Geological Survey.

Methodological considerations –

Nitrate analysis

Pre-1970 Colorimetric phenoldisulphonic acid method.After 1970 Colorimetric cadmium reduction.

Organic nitrogen

• “Albuminoid ammonia” method used on most samples before 1940.Total N = Alb. NH3 + NO3 + NO2 + NH3

• Kjeldahl nitrogen used on all samples since 1975.Total N = TKN + NO3 + NO2

Sample handling• “Composite samples” – time-averaged.

• Discrete samples – single time point.

• Holding time in older samples.

Willamette River at Salem, ORDrainage area 19,000 km2

Human impacts in the watershed• Slaughterhouse and animal processing

facilities.• Urban wastewater and runoff.• Pulp and paper mill waste.• Logging / forestry.• Some agriculture in lower basin.

Noted historical water quality problems• Low oxygen concentration around

Salem (largely solved by 1972 through discharge permit system).

• Untreated urban wastewater (successive rounds of treatment plant updates 1930s through 1960s).

• Depleted salmon population (ongoing, improvements after 1970).

Illinois RiverDrainage area 41,000 km2 (upper)

69,000 km2 (lower)

Human impacts in the watershed• Diversion of Chicago River (1890).• Urban runoff and wastewater.• Intense row crop agriculture.• Bottom land farms maintained through

levee & drainage districts.• Industrial effluent.

Noted historical water quality problems• Water-borne disease outbreaks in late

1800s.• Fisheries virtually destroyed by 1920s.• Low oxygen associated with

slaughterhouse wastes in Pekin/Peoria area.

Schuylkill RiverDrainage area 4,902 km2

Human impacts in the watershed• First municipal water works in the nation

(1802).• Mine waste in upper watershed (1860s).• Heavy industry (1880s).• Moderate agriculture in lower watershed

outside of Philadelphia.• Intense urban development in lower

watershed.

Noted historical water quality problems• Numerous government reports between

1866 and 1946 recommended abandoning the Schuylkill as a drinking water source.

• Coal mine silt pollution in upper basin.• Dramatic water quality improvements

resulted in the Schuylkill River being designated as a Federal Scenic River by 1978.

emerging perspectives on continental-scale riverine carbon fluxes david butman, yale university

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