Eutrophication A Review of Its Process and Ecological Impacts

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EutrophicationA Review of Its Process and
Ecological Impacts

• Yang Zhang

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Introduction

• Previously,

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• In the past few decades,

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• Definition
• The enrichment of water by nutrients,
  stimulating and array of symptomatic changes
  including increased production of algae and/or
  high plants, which can adversely affect the
  diversity of the biological system, the quality
  of the water, and the uses to which the water may
  be put.

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Topics of Discussion

• CAUSES
• Nutrient limitation
• Nutrient input sources
• Nutrient loading
• PROCESS
• ASSOCIATED PHYTOPLANKTONS
• CONSEQUENCES

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Causes of Eutrophication

• Anthropogenic inputs

N, P nutrient enrichment
Algae bloom
Allochthonous C
Autochthonous C
Organic matter loading
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Nutrient Limitation

• Basic elements
• C, H, O
• Macronutrients
• Ca, Mg, K, P, N, S, Fe, Si
• Trace elements
• B, Cl, Co, Cu, Mn, Mu, Zn, vitamin

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Nitrogen
and
Phosphorus
Are the key nutrients causing eutrophication
problems
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Note the bright green color caused by algae
stimulated by the experimental addition of
phosphorus for the 26th consecutive year. Lake
305 in the background is unfertilized
Blue green "algae" (Cyanobacteria) were able to
"fix" nitrogen that had diffused naturally into
the lake from the air, thereby making the
nitrogen available for supporting algal growth.
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Nitrogen enrichment not only causes algae blooms,
but also
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Nitrogen formulation can regulate the cell size
distribution of phytoplankton communities

• Smaller species have a higher preference for
  ammonia uptake over nitrate than larger species
• Larger species have the capacity for more
  internal storage of nutrients and become dominant
  in fluctuating nutrient regimes

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Nutrient Input Sources
Nonpoint sources
Run off from farmlands Run off from lawns and
paved areas
Industry Waste water treatment plants
Point sources
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Nutrient Loading

• P
• Naturally,
• Exists as phosphate
• Sorbed to soil particles
• Liberated by weathering
• Not easily leached out

--Anthropogenically, Human-caused changes in the
global P budget have caused P to accumulate in
upland soils, and increasing soil P levels
elevate the potential P runoff to aquatic
ecosystems.
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• N
• Naturally,
• Anthropogenically,
• Many forms of nitrogen, especially fertilizers,
  are released to the environment
• Easily leached out of the upper soil layers by
  rainfall

Nitrogen fixation
Nitrification
Denitrification
N2
NH4
NO3-
N2
oxic
anoxic
Cell mass
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Process of Eutrophication
High nutrient release

• 
  

Anaerobic benthic
High algal photosynthesis
High organic matter
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Algae Associated with Eutrophication

• Red tides
• Red algae
• Furcellaria
• Phycodrys

• Green tides
• --Green algae
• Chlorophytes
• Cryptophytes
• Cyanobacteria
• Diatoms
• Dinoflagellates

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Consequences of Eutrophication

• Destroy food chain
• Algae bloom algae
  species change
• block sunlight
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  loss of available food
• Underwater grasses die
• Herbivorous die
  displacement of fish
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  and crabs

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• Anoxic water kills fish and crabs

High nutrient release


Anaerobic benthic
High algal photosynthesis
High organic matter
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• Produce toxic chemicals
• Toxins produced by cyanobacteria can not be
  removed by conventional water treatment processes
• Causing many chronic health problems in humans.

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Thank you!