Hydrological and biogeochemical controls on watershed dissolved organic matter transport: pulse‐shunt concept

Hydrological precipitation and snowmelt events trigger large “pulse” releases of terrestrial dissolved organic matter (DOM) into drainage networks due to an increase in DOM concentration with discharge. Thus, low‐frequency large events, which are predicted to increase with climate change, are respon...

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Bibliographic Details
Published in:Ecology (Durham) Vol. 97; no. 1; pp. 5 - 16
Main Authors: Raymond, Peter A, Saiers, James E, Sobczak, William V
Format: Journal Article
Language:English
Published: United States Brooklyn Botanical Garden 2016
ECOLOGICAL SOCIETY OF AMERICA
Ecological Society of America
Subjects:
Aquatic ecosystems
Aquatic plants
Biogeochemistry
Brackish
climate
Climate change
Coastal environments
CONCEPTS & SYNTHESIS: EMPHASIZING NEW IDEAS TO STIMULATE RESEARCH IN ECOLOGY
Creeks & streams
Discharge
Dissolved organic matter
DOM
Drainage
Drainage patterns
Ecology
Ecosystem
Environmental Monitoring - methods
Fluxes
Hydrology
Mathematical models
Metabolism
Models, Theoretical
Networks
New England
nutrients
Organic chemicals
Organic Chemicals - analysis
Precipitation
prediction
Predictions
pulse event
Rivers
Robustness (mathematics)
Scaling
Snowmelt
snowmelt event
statistics
Storms
Streams
Terrestrial environments
USA
Velocity
Water - chemistry
Water Movements
watershed
Watersheds
ISSN:0012-9658, 1939-9170
Online Access:Get full text
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Summary:Hydrological precipitation and snowmelt events trigger large “pulse” releases of terrestrial dissolved organic matter (DOM) into drainage networks due to an increase in DOM concentration with discharge. Thus, low‐frequency large events, which are predicted to increase with climate change, are responsible for a significant percentage of annual terrestrial DOM input to drainage networks. These same events are accompanied by marked and rapid increases in headwater stream velocity; thus they also “shunt” a large proportion of the pulsed DOM to downstream, higher‐order rivers and aquatic ecosystems geographically removed from the DOM source of origin. Here we merge these ideas into the “pulse‐shunt concept” (PSC) to explain and quantify how infrequent, yet major hydrologic events may drive the timing, flux, geographical dispersion, and regional metabolism of terrestrial DOM. The PSC also helps reconcile long‐standing discrepancies in C cycling theory and provides a robust framework for better quantifying its highly dynamic role in the global C cycle. The PSC adds a critical temporal dimension to linear organic matter removal dynamics postulated by the river continuum concept. It also can be represented mathematically through a model that is based on stream scaling approaches suitable for quantifying the important role of streams and rivers in the global C cycle. Initial hypotheses generated by the PSC include: (1) Infrequent large storms and snowmelt events account for a large and underappreciated percentage of the terrestrial DOM flux to drainage networks at annual and decadal time scales and therefore event statistics are equally important to total discharge when determining terrestrial fluxes. (2) Episodic hydrologic events result in DOM bypassing headwater streams and being metabolized in large rivers and exported to coastal systems. We propose that the PSC provides a framework for watershed biogeochemical modeling and predictions and discuss implications to ecological processes.
Bibliography:http://dx.doi.org/10.1890/14-1684.1
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ISSN:0012-9658
1939-9170
DOI:10.1890/14-1684.1