dissolved organic carbon dissolved inorganic carbon bix ... · graduate summer research fellowship;...
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DIC/
DOC
conc
entr
atio
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
Dissolved Organic M
atter Quality
RecalcitrantLabile
Streamflow
Labile organic matter from sewage leaks and storm drains can contribute to DOM pool.
Leaf-free seasonPeak growing season: increased ET
Resp
iratio
n
Prim
ary
Prod
uctio
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 implications Rose M. Smith1, Sujay S. Kaushal1
1University 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.
- 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 d
ay
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
pC
O2
atm 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