The Confounding Effect of River Discharge on Estuarine Response to Nutrient Loading
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The Confounding Effect of River Discharge on Estuarine Response to Nutrient Loading. Craig A. Stow NOAA Great Lakes Environmental Research Laboratory Ann Arbor, MI.

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The Confounding Effect of River Discharge on Estuarine Response to Nutrient Loading

Craig A. Stow

NOAA Great Lakes Environmental Research Laboratory

Ann Arbor, MI

Borsuk, M. E., C. A. Stow, and K. H. Reckhow. 2004. Confounding effect of flow on estuarine response to nitrogen loading. Journal of Environmental Engineering, 130: 605-614.

Additional Insights and Inputs provided by Conrad Lamon and Song Qian


The neuse river basin
The Neuse River Basin Response to Nutrient Loading

Courtesy USGS


Vollenweider Cross-Sectional Lake Nutrient Loading Model Response to Nutrient Loading

  • Single Lake Relationship:

  • Positive

  • Negative

  • Nonlinear

Brazenly stolen from:

Vollenweider, R.A. 1976. Advances in defining critical loading levels for phosphorus in lake eutrophication. Mem. Ist. Ital. Idrobiol., 33:53-83.


Residence Time Response to Nutrient Loading

Turbidity

Salinity

Temperature

River Flow

Nutrient

Concentration

Eutrophication

Nutrient Loading

Estimated

Nutrient Loading

Estimated

Concentration=

f(Flow)


River discharge highly variable – even on relatively long time-scales

Drives Nutrient Load Variability at this scale


Concentration:Flow relationships idiosyncratic: positive, negative, or non-monotonic

In the Neuse the relationship was negative

Log concentration

Log flow

  • High load = low concentrations

Data Provided by:

NC DENR DWQ – nutrient concentrations

USGS – daily flow


0 negative, or non-monotonic

10

20

Upper

30

New

Bern

40

50

Middle

180

60

170

l

70

Bend

80

160

l

90

150

100

140

l

110

Water Quality Station

Hydrographic Station

l

130

120

l

l

l

l

N

10 miles

10 kilometers

Model Sections

River

Upper

Middle

Lower

Bend


Chlorophyll a Model negative, or non-monotonic

(Bayesian multilevel piecewise lognormal model)


Estuarine N Concentrations vs. Annual N Load negative, or non-monotonic

Ft. Barnwell

Swift Creek

New Bern

Broad Creek

Oriental

Pamlico


Estuarine P Concentrations vs. Annual P Load negative, or non-monotonic

Ft. Barnwell

Swift Creek

New Bern

Broad Creek

Oriental

Pamlico


Summary negative, or non-monotonic

Nonlinear chlorophyll, flow (~ load) relationship on short time-scales

Relationship differs systematically along spatial gradient

Maximum differs systematically along spatial gradient

No relationship between nutrient load, concentration on medium time-scales

This may differ among systems


TMDLs negative, or non-monotonic

Nutrient Loading

Nutrient Loading

Eutrophication

Eutrophication

Hypoxia

Hypoxia




April 2006 - U.S. Court of Appeals District of Columbia Circuit ruled that EPA-approved plan to limit pollution into Anacostia River contrary to Clean Water Act requirements to set "total maximum daily loads" of pollutants.

January 2007 -- United States Supreme Court let stand lower court ruling requiring limits on pollution allowed in Anacostia River each day. 


River Flow Circuit ruled that EPA-approved plan to limit pollution into Anacostia River contrary to Clean Water Act requirements to set "total maximum

Nutrient

Concentration

Eutrophication

Nutrient Loading

?

Hypoxia

Upper Trophic Level

Effects


The End Circuit ruled that EPA-approved plan to limit pollution into Anacostia River contrary to Clean Water Act requirements to set "total maximum


River Flow Circuit ruled that EPA-approved plan to limit pollution into Anacostia River contrary to Clean Water Act requirements to set "total maximum

Hypoxia

Nutrient Loading

Estimated

Nutrient Loading


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