Post on 05-Jan-2016
description
Nutrients & Dissolved Oxygen
Jonathan PennockUniversity of New Hampshire
Marine Program, NH Sea Grant & Jackson Estuarine Laboratory
EutrophicationPositive Versus Negative Effects
Oligotrophic MesotrophicEutrophic Dystrophic
Phytoplankton
Zooplankton
Pelagic Fish
Bottom Oxygen
Benthos
Benthic Fish
NOAA Estuarine Eutrophication Assessment
Bricker 1999
Environmental Protection Agency
Nitrogen in Great Bay
Have nitrogen concentrations in Great Bay changed significantly over time?
Yes. The total nitrogen load to the Great Bay Estuary increased by 42% in the past 5 years. Dissolved inorganic nitrogen concentrations have increased in Great Bay by 44% in the past 28 years.
•Q
•A
Nitrogen Loads to Great BayTotal N Load
2002-2004
1,097 tons/yr
2006-2008
1,558 tons/yr
Percent Change
42%
•Data Source: PREP
WWTFs
484.64 tons/yr
31%
Groundwater
31.28 tons/yr
2%
Atmospheric
27.92 tons/yr
2%
Tributaries and Runoff
1014.00 tons/yr
65%
Dissolved Nitrogen
Dissolved Inorganic Nitrogen
44% increase over 28 years
Ru Morrison
Chlorophyll-a & Suspended Solids
Suspended Solids
123% increase over 28 years
Chlorophyll-a
28% increase over 28 years
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Chlorophyll-a
0 1 2 3 4 5 Kilometers
N
Chlorophyll-a
0.1 - 2 ug/L%2 - 5 ug/L%5 - 10 ug/L%10 - 20 ug/L%20 - 60 ug/L%
Sample Size
N >=10 Results#SN <10 Results#S
Chlorophyll Concentration
Dissolved Oxygen
How often do dissolved oxygen levels in the estuary fall below state standards?
Rarely in the bays and harbors but often in the tidal rivers.
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•A
Oxygen Depletion at Datasondes
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#S #S MinimumDissolvedOxygen
0 1 2 3 4 5 Kilometers
N
Minimum Dissolved Oxygen
8 - 10 mg/L%6 - 8 mg/L%5 - 6 mg/L%4 - 5 mg/L%3 - 4 mg/L%
Sample Size
N >=10 Results#SN <10 Results#S
Dissolved Oxygen Concentration
Dissolved Oxygen Concentration
Ru Morrison
Squamscott River Sonde (Data from August-October in 2006-2009)
0
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300:0
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Time of Day
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mb
er
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es t
hat
the D
ail
y
Maxim
um
/Min
imu
m D
O (
in m
g/L
) O
ccu
rred
at
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is T
ime
DO maximum DO minimum
Squamscott River Sonde (Data from August-October in 2006-2009)
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er
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es t
hat
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h o
r L
ow
Tid
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rred
at
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is T
ime
High Tide Low Tide
Dissolved Oxygen Diel Variability
Phil Trowbridge
Data Gaps
• Additional Sampling Stations in the Bay are Needed to Provide Better
Insight and Averages for the Bay Proper…
• A Robust Nutrient Loading/Sink Model is Needed to Determine Specific
Nutrient Loading and Ultimate Fate of Nutrients in the System…
• There are No Data on Phytoplankton Production in the Estuary…
• …
Thank You!