Eutrophication

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Eutrophication

• Nutrient Enrichment Algal Growth

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Content

• Systems analysis
• Algal Growth
• Species
• Light
• Temperature
• Nitrogen
• Phosphorous
• Limiting Factors
• Other Processes

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Global Primary Production
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Phytoplankton What's the Big Deal?

• Fastest growing plants
• Very small
• Never dry
• Food for a catch of 100 million tons fish/yr.
• Produces much oxygen
• And removes CO2 from the atmosphere

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EutrophicationIs this a Problem?

• Nutrient enrichment is goodPromotes biological
  production
• Too much is bad
• Turbid water
• Oxygen deficit problems
• Toxic algae
• Red Tide, Shellfish Poisoning, Ciguaterra

http//www.redtide.whoi.edu/hab/
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The Transport Equation
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Systems Analysis

• State Variables
• Processes
• Forcing Functions

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Primary Production, Basic Equations
Algal Carbon PRPC-GRPC-DEPC-SEPC Algal Nitrogen
PRPN-GRPN-DEPN-SEPN Algal Phosphorous
PRPP-GRPP-DEPP-SEPP Chlorophyll-a
PRCH-DECH-SECH Zooplankton PRZC-EKZC-DEZC Detritu
s Carbon DEPCSLMCSLACEKZCDEZC-REDC-SEDC Detri
tus Nitrogen DEPNSLMNSLANEKZNDEZN-REDN-SEDN D
etritus Phosphorous DEPPSLMPSLAPEKZPDEZP-REDP
-SEDP Inorganic Nitrogen REDNREZNRESN-UNMNREBN
Inorganic Phosphorous REDPREZPRESP-UNMPREBP D
issolved Oxygen ODPCODMCODAC-ODDC-ODZC-ODSCREA
R Sediment Carbon SEPCSEDC-REDC Macroalgae
PRMC-SLMC-REMC Sea grass PRAC-SLAC-REAC
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Naming Conventions

• Be Consistent Systematic
• State Variables Two letters, PC, DO etc
• Processes 4 letters PRPC, ODDC
• Do not hope for perfection

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Primary production, Basic Equation
PRPCµmax(art)f(T)f(I)f(P)f(N)PC

• Where
• µmax is a specific maximal algal growth rate
• T is temperature
• I is light insulation
• P is phosphorous
• N is nitrogen

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Primary production, Biomass
PRPCµmax(art)f(T)f(I)f(P)f(N)PC
Where µmax is a specific maximal algal growth
rate T is temperature I is light insolation P is
phosphorous N is nitrogen
Chlorophyll in lake Mjøsa
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The C14-method

• The Sea The Danish way to power and glory
• Steemann Nielsen the Galathea expedition
• Addition of C14 in light and darkness

http//www.iopan.gda.pl/kaczmar/bdo/primprod.htm
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Growth Limitation
Exponential Growth
Logistic Growth
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Limiting factor

• The factor in short supply decides the growth
• A chain is not stronger than its weakest link
• If you control one factor, you control all

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Gross- and Net Production
Gross GBPRPCNet GNGB-R Where RkrPC and
krrespiration parameter
http//dixon.gso.uri.edu/images/line-d.jpg
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Species Succession

• Diatoms
• Made of glass
• Sinks quickly
• Dinoflagellates
• Swimming Algae
• Cyanobacteria
• Floats
• Make their own nitrogen

http//www.comet.chv.va.us/GEK/phytob.htm
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Algal Composition

• C106H263O110N16P
• C 36, N 6,3, P0,9
• The ratios are variable
• Equivalent oxygen demand 0.96 mgO2/mg dry weight
• Oxygen/Carbon Ratio 2.6

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Primary production, Temperature
PRPCµmax(art)f(T)f(I)f(P)f(N)PC
Where µmax is a specific maximal algal growth
rate T is temperature I is light insulation P is
phosphorous N is nitrogen
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Temperature Dependence
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Primary production, Light
PRPCµmax(art)f(T)f(I)f(P)f(N)PC
Where µmax is a specific maximal algal growth
rate T is temperature I is light insulation P is
phosphorous N is nitrogen
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Light and Depth
Light
The Photic Zone
Depth
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Algal Growth and Light
Photosynthesis
Saturation
Inhibition
Light
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Algal Production and Depth
R
PB
The total production is integrated over depth
Compensation depth
GBR
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Secchi Depth and Chlorophyll
Danish Coastal Waters
10m
10
100 µg/l
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Primary production, Nutrient
PRPCµmax(art)f(T)f(I)f(P)f(N)PC
Where µmax is a specific maximal algal growth
rate T is temperature I is light insulation P is
phosphorous N is nitrogen
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Primary Production
Algal Carbon PRPC-GRPC-DEPC-SEPC Algal Nitrogen
PRPN-GRPN-DEPN-SEPN Algal Phosphorous
PRPP-GRPP-DEPP-SEPP Chlorophyll-a
PRPH-DEPH-SEPH Zooplankton PR-ZC-DEZC Detritus
Carbon DEPCSLMCSLACEKZCDEZC-REDC-SEDC Detritu
s Nitrogen DEPNSLMNSLANEKZNDEZN-REDN-SEDN Det
ritus Phosphorous DEPPSLMPSLAPEKZPDEZP-REDP-S
EDP Inorganic Nitrogen REDNREZNRESN-UNMNREBN I
norganic Phosphorous REDPREZPRESP-UNMPREBP Dis
solved Oxygen ODPCODMCODAC-ODDC-ODZC-ODSCREAR
Sediment Carbon SEPCSEDC-REDC Macroalgae
PRMC-SLMC-REMC Sea grass PRAC-SLAC-REAC
Algal Carbon PRPC-GRPC-DEPC-SEPC Algal Nitrogen
PRPN-GRPN-DEPN-SEPN Algal Phosphorous
PRPP-GRPP-DEPP-SEPP Chlorophyll-a
PRPH-DEPH-SEPH Zooplankton PR-ZC-DEZC Detritus
Carbon DEPCSLMCSLACEKZCDEZC-REDC-SEDC Detritu
s Nitrogen DEPNSLMNSLANEKZNDEZN-REDN-SEDN Det
ritus Phosphorous DEPPSLMPSLAPEKZPDEZP-REDP-S
EDP Inorganic Nitrogen REDNREZNRESN-UNMNREBN I
norganic Phosphorous REDPREZPRESP-UNMPREBP Dis
solved Oxygen ODPCODMCODAC-ODDC-ODZC-ODSCREAR
Sediment Carbon SEPCSEDC-REDC Macroalgae
PRMC-SLMC-REMC Sea grass PRAC-SLAC-REAC
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Growth Equations, Intracellular
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Growth Equations, structure
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Growth Equations
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Growth Rates
S,C,X
S
S0
X
Ci,max
CiCaCe
Ce
Sc
C
Ca
Time
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Growth Rate and P
µ/µmax
Ci,max
Monod kinetics
Ca
Ci

• Halfsaturation

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Vollenweider updated
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Growth Rate and N
Ci,max
µ/µmax
Ci
Ca
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Chemostate Experiments
QXind
QXud
Algal production
QSind
QSud
Balance for biomass Balance for Nutrient
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Chemostat Experiment, Special Case
Freely available dissolved substrateThe Algae
grow with highest possible rates and are filled
with nutrients

• NB No algae in rivers

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Nitrogen or Phosphorous
Thats the Question

• Denmark has Chosen both
• Agriculture pointed on P!
• The cities on N!

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Liebigs Law of the Minimum
Justus Liebig, a German agricultural chemist,
proposed in 1840 that plants were limited by that
element in the shortest supply relative to their
capabilities. A useful concept, although it does
not account for

• toxicity at high levels of that element
• suggests that only a single element is limiting
• fails to consider interactions

http//www.cals.ncsu.edu/ncsu/cals/course/bo360/ph
yseco1/tsld006.htm
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Determine Limitation?

• Measure inorganic material in water
• Plt2 mg/mg3
• Nlt14mg/m3
• Bioassays
• Models
• Political vote!

http//www.brooks.af.mil/HSC/products/doc95.html
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Turnover Rates of Nutrients

• Difference in rates
• P is recycled faster than N
• Degradable fractions
• Organic N is quite stable

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Transients

• P can be accumulated in and released from
  sediment
• Which delays effect of treatment
• N is gone with the water
• Treatment works immediately

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Natural Background

• Boundary values
• The Oceans are primarily N-limited (Iron)
• Denitrification/N-fixation
• Baltic Sea
• In lakes the boundary for P is zero
• The past
• No changes in the major oceans
• A 2-200 times in lakes and coastal areas

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Discussion N and/or P

• P in lakes and some lagoons
• P-removal will work
• N i in the sea
• N-removal will work
• P-removal is waste of money

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Other Processes

• Use 1.order kinetics as a start
• Examples BOD oxygenation, Bacteria Decay

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The End