Export and metabolism of carbon in urban watersheds: Climate implications Rose M. Smith 1, Sujay S....
1
DIC/DOC concentration [DOC] [DIC] Low baseflow Deep flow paths Intermediate---- high baseflow Storm flow Shallow flow paths DOC quantity and quality can be influenced by w arm ing/salinity at baseflow. Stream flow Based Conceptual Fram ew ork for Urban Carbon Transport DOM lability R e c a l c i t r a n t L a b i l e Stream flow Labile organic m atterfrom sew age leaksand storm drainscan contribute to DOM pool. Leaf-free season Peakgrow ing season: increased ET Respiration Primary Production shaded headw aters non-shaded river -4 -2 0 2 1 10 100 NEP gC m 2 day PaintBranch -4 -2 0 2 1 10 100 D ischarge ft 3 s 1 NEP gC m 2 day S eason S pring Sum m er Fall Winter Sligo C reek -4 -2 0 2 10 100 1000 NEP gC m 2 day N ortheastBranch Export and metabolism of carbon in urban watersheds: Climate implications Rose M. Smith 1 , Sujay S. Kaushal 1 1 University of Maryland College Park Motivation Urbanization and climate change influence riverine carbon fluxes to estuaries by altering the hydrologic regime, water temperature, and anthropogenic sources of organic matter. Carbon cycling has implications for freshwater food webs, estuarine ecosystems, and greenhouse gas emissions, however little is known about how land use and climatic factors influence carbon processing and transport in rivers. Objectives 1) Quantify rates of carbon transport and metabolism in four urban watersheds which vary in catchment size 2) Develop a conceptual framework for understanding shifts in carbon export, quality, and metabolism across flow conditions in developed watersheds Methods - Dissolved C Export : 3 years of biweekly sampling + USGS LOADEST model - Metabolism: Baysean Metabolic model (BaMM) used to estimate GPP and ER based on diurnal DO and temperature over 2 years - Organic Matter Quality : Lability metrics quantified based on spectrofluorometric excitation-emission measurements. - CO 2 concentrations: Measured DIC and pH biweekly and determined the proportion of dissolved CO 2 using CO2SYS model of the inorganic carbon system. Acknowledgements: National Science Foundation, Maryland Sea Grant Fellowship Program, Maryland Water Resources Research Center, University of Maryland Graduate Summer Research Fellowship; ESSIC/Geology Travel Grant Conclusions - Annual DOC export from highly developed streams was comparable to forested streams in similar regions and DOM quality resembles soil/leave despite reduced forest cover. - Light availability may limit GPP more than nutrients. - CO 2 concentrations are on par with DOC, and streams were net sources of CO 2 throughout the year. - Greenhouse gas implications of C and N loading in urban areas warrant further study DEPARTMENT OF GEOLOGY 1. Dissolved Carbon form and quality varies with flow : DOC was flushed and DIC was diluted with increasing flow. Dissolved organic matter (DOM) character became less labile at high flows. 4. Net Ecosystem Productivity across flow conditions. NEP (net ecosystem productivity, GPP- ER) was greatest at medium flows for all sites. Periods of positive NEP were greater in the open-channel site compared to smaller streams -5.0 -2.5 0.0 2.5 D ec-2011 Apr-2012 Aug-2012 D ec-2012 Apr-2013 Aug-2013 D ec-2013 Apr-2014 Aug-2014 gC m 2 day GPP ER NEP Stream M etabolism :N ortheastBranch Anacostia atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration atm ospheric concentration 1000 2000 3000 4000 5000 6000 NERP PBCP SLIG O Stream pC O 2 atm S ite NERP PBCP SLIGO C arbon D ioxide Sampling sites in the Anacostia Watershed Results 2. Daily stream metabolism and seasonal variations: Streams were generally heterotrophic (ER>GPP) with limited periods of net-production (GPP>ER) during spring. Data shown from one site (Northeast Branch). 3. Carbon Dioxide: concentrations of CO 2 was super-saturated compared to the atmosphere on all dates. Paint Branch Northeast Branch Northwes t Branch Sligo Creek Conceptual Framework 5. Conceptual Framework highlighting the influence of flow on carbon cycle parameters in urban streams. As DOC fluxes increase, DOM quality becomes less labile. Anthropogenic influences such as warming, salinization, sewage, and stormwater may influence DOC fluxes and DOM quality. In-stream GPP and ER rates peaked during moderate flow conditions and reduced during low- flow due to seasonal shading from riparian trees which coincides with high evapotranspiration. 0 4 8 12 16 10 1000 D O C m g/L D issolved O rganic C arbon 5 10 15 20 25 10 1000 D ischarge (cfs) D IC m g/L D issolved Inorganic C arbon 0.6 0.7 0.8 10 1000 BIX S ite NERP NW HV PBCP SLIG O BIX:Freshness Index Shaded headwaters Non-shaded River
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Transcript of Export and metabolism of carbon in urban watersheds: Climate implications Rose M. Smith 1, Sujay S....
DIC
/DO
C c
on
cen
tra
tio
n
[DOC]
[DIC]
Low baseflowDeep flow paths
Intermediate---- high baseflow
Storm flowShallow flow paths
DOC quantity and quality can be influenced by warming/salinity at baseflow.
Streamflow Based Conceptual Framework for Urban Carbon Transport
DOM lability
Disso
lved
Org
an
ic Ma
tte
r Qu
ality
Re
calcitra
nt
Lab
ile
Streamflow
Labile organic matter from sewage leaks and storm drains can contribute to DOM pool.
Leaf-free seasonPeak growing season: increased ET
Re
spir
ati
on
P
rim
ary
Pro
du
ctio
n
shaded headwatersnon-shaded river
-4
-2
0
2
1 10 100
NE
P g
C m
2 d
ay
Paint Branch
-4
-2
0
2
1 10 100
Discharge ft3s 1
NE
P g
C m
2 d
ay
Season
Spring
Summer
Fall
Winter
Sligo Creek
-4
-2
0
2
10 100 1000
NE
P g
C m
2 d
ay
Northeast Branch
Export and metabolism of carbon in urban watersheds: Climate implicationsRose M. Smith1, Sujay S. Kaushal1
1University of Maryland College Park
MotivationUrbanization and climate change influence riverine carbon fluxes to estuaries by altering the hydrologic regime, water temperature, and anthropogenic sources of organic matter. Carbon cycling has implications for freshwater food webs, estuarine ecosystems, and greenhouse gas emissions, however little is known about how land use and climatic factors influence carbon processing and transport in rivers.
Objectives1) Quantify rates of carbon transport and metabolism in four urban watersheds which vary in catchment size
2) Develop a conceptual framework for understanding shifts in carbon export, quality, and metabolism across flow conditions in developed watersheds
Methods- Dissolved C Export: 3 years of biweekly sampling +
USGS LOADEST model- Metabolism: Baysean Metabolic model (BaMM) used
to estimate GPP and ER based on diurnal DO and temperature over 2 years
- Organic Matter Quality: Lability metrics quantified based on spectrofluorometric excitation-emission measurements.
- CO2 concentrations: Measured DIC and pH biweekly and determined the proportion of dissolved CO2 using CO2SYS model of the inorganic carbon system.
Acknowledgements: National Science Foundation, Maryland Sea Grant Fellowship Program, Maryland Water Resources Research Center, University of Maryland Graduate Summer Research Fellowship; ESSIC/Geology Travel Grant
Conclusions- Annual DOC export from highly developed
streams was comparable to forested streams in similar regions and DOM quality resembles soil/leave despite reduced forest cover.
- Light availability may limit GPP more than nutrients.
- CO2 concentrations are on par with DOC, and streams were net sources of CO2 throughout the year.
- Greenhouse gas implications of C and N loading in urban areas warrant further study
DEPARTMENT OF GEOLOGY
1. Dissolved Carbon form and quality varies with flow : DOC was flushed and DIC was diluted with increasing flow. Dissolved organic matter (DOM) character became less labile at high flows.
4. Net Ecosystem Productivity across flow conditions.
NEP (net ecosystem productivity, GPP-ER) was greatest at medium flows for all sites. Periods of positive NEP were greater in the open-channel site compared to smaller streams with seasonal shading from riparian trees.
-5.0
-2.5
0.0
2.5
Dec-2011 Apr-2012 Aug-2012 Dec-2012 Apr-2013 Aug-2013 Dec-2013 Apr-2014 Aug-2014
gC
m2
day
GPP
ER
NEP
Stream Metabolism: Northeast Branch Anacostia
atmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentrationatmospheric concentration
1000
2000
3000
4000
5000
6000
NERP PBCP SLIGOStream
pCO
2 a
tm Site
NERP
PBCP
SLIGO
Carbon Dioxide
Sampling sites in the Anacostia Watershed
Results
2. Daily stream metabolism and seasonal variations: Streams were generally heterotrophic (ER>GPP) with limited periods of net-production (GPP>ER) during spring. Data shown from one site (Northeast Branch).
3. Carbon Dioxide: concentrations of CO2 was super-saturated compared to the atmosphere on all dates.
Paint Branch
Northeast Branch
Northwest
Branch
Sligo Creek
Conceptual Framework
5. Conceptual Framework highlighting the influence of flow on carbon cycle parameters in urban streams. As DOC fluxes increase, DOM quality becomes less labile. Anthropogenic influences such as warming, salinization, sewage, and stormwater may influence DOC fluxes and DOM quality. In-stream GPP and ER rates peaked during moderate flow conditions and reduced during low-flow due to seasonal shading from riparian trees which coincides with high evapotranspiration.
0
4
8
12
16
10 1000
DO
C m
g/L
Dissolved Organic Carbon
5
10
15
20
25
10 1000Discharge (cfs)
DIC
mg/L
Dissolved Inorganic Carbon
0.6
0.7
0.8
10 1000
BIX
Site
NERP
NWHV
PBCP
SLIGO
BIX: Freshness Index
Shaded headwaters Non-shaded River
