Transcript Richard Sandford, Plymouth University

Eutrophication
Eutrophication in the Sea of Azov. Source: SeaWiFS Project,
NASA/Goddard Space Flight Center and ORBIMAG
Developed by Richard Sandford with
contributions from Martin Bloxham and Paul Worsfold,
The lecture will:
1. DEFINE eutrophication
2. Explain the CAUSES and SOURCES of eutrophication
3. Discuss the ENVIRONMENTAL IMPACTS of eutrophication
4. Look at the SOCIO-ECONOMIC consequences of eutrophication
5. Look at POLICY/REMEDIATION
6. Explain how to MONITOR Eutrophication
7. Examine BLACK SEA CASE STUDY
8. Present REFERENCES and LINKS to information sources
1. Defining Eutrophication
Most limnologists consider eutrophication as an increase in the rate of supply of
organic matter to an ecosystem.
For marine scientists, eutrophication (GESAMP, 1990) is “used simply to mean
‘enhanced nourishment’ and refers to the stimulation of aquatic plant growth by
mineral nutrients, particularly the combined forms of phosphorus or nitrogen”.
For more information on defining eutrophication, click Here
2. Causes of Eutrophication
The immediate causes of eutrophication are listed below. For more detailed
information on the underlying causes of eutrophication, click on the
immediate cause of interest:
2.1 Enhanced nutrient inputs
2.2 Increased recycling/ mobilisation of nutrients
2.3 Trapping of nutrients (e.g. in river impoundments)
3. Environmental Impacts of Eutrophication
Here are some of the impacts of eutrophication. The consequences
of each of these impacts will be explained in the lecture. For more information
click on the impact of interest:
3.1 Decrease in the transparency of water
3.2 Development of anoxic conditions (low oxygen levels)
3.3 Increased algal blooms
3.4 Loss of habitat (e.g. Sea grass beds)
3.5 Change in dominant biota (e.g. Changes in plankton and macrophyte
community structure or changes in fish composition)
3.6 Decrease in species diversity
3.7 Change in the aesthetic value of the water body
4. Socio-economic Consequences
of Eutrophication
Here are some of the main socio-economic consequences of eutrophication:
4.1 Increased vegetation may impede water flow and the movement of boats
4.2 The water may become unsuitable for drinking even after treatment
4.3 Decrease in the amenity value of the water (e.g. it may become unsuitable
for water sports such as sailing)
4.4 Disappearance of commercially important species (such as trout)
4.5 Loss of tourism/recreation (swimming, boating)
4.6 Loss of aesthetic value: visual disamenity of algal blooms in lakes
5. Remediation Measures
A reduction in the extent of artificial eutrophication can (in principle) be
achieved by:
5.1 Reduction in the use of phosphates as builders in detergents
5.2 Reduction in the use of nitrate containing fertilisers
5.3 Implementation of tertiary sewage treatment methods which remove
phosphate and nitrate
5.4 Improvements in agricultural practices (economising on fertiliser use and
improving land use)
5.5 Aeration of lakes and reservoirs to prevent oxygen depletion particularly
during algal blooms
5.6 Restoration of natural wetlands, efficient in nutrient removal
5.7 Removing phosphate-rich plant material from affected lakes
5.8 Removing phosphate-rich sediments by dredging
6. Monitoring of Nutrients
This section looks at:
•
The biogeochemistry of nutrients (nitrogen, phosphorus and silicon)
•
Methods of nutrient sampling and storage handling
•
Techniques for the determination of nutrients in aquatic environments
•
Validation of nutrient data
For more information on nutrient monitoring, click Here
7. References
Mee, LD, Bloxham, M, Glegg, GA, Hart, V, Beaumont, N and Payne, S (2000) Global
International Waters Assessment; draft methodology, University of Plymouth.
GESAMP (1990) (IMO/FAO/UNESCO-IOC/WMO/WHO/IAEA/UN/UNEP Joint Group of
Experts on the Scientific Aspects of Marine Pollution) The State of the Marine Environment.
GESAMP No. 39, 111pp, London.
Anderson, N.J. , Historical changes in epilimnetic phosphorus concentrations in six rural lakes
in Northern Ireland, Freshwater Biology, 1997, 38, 427-440.
Bloxham, M., Nixon, E., McGovern, E., Rowe, A., Smyth, M. and Duffy, C., Winter Nutrient
Monitoring of the Western Irish Sea- 1990-2000, Irish Marine Environment and Health Series,
2001.
Useful Web links are on the next page.....
8. Useful Links
Environment Agency (EA) Home
EA Water Framework Directive
EA Nutrients in rivers, lakes and coastal waters
EA Excess nutrients in rivers, lakes and coastal waters - an overview
EA Nitrate in rivers and groundwater
Defra Nitrates from Agriculture
Defra Water Framework Directive
Water UK Home
United Nations Environment Programme (UNEP) Eutrophication information
Institute of Grassland and Environmental Research (IGER) Home
More useful links are on the next page.....
8. Useful Links
Global International Waters Assessment (GIWA) Web site Home
Oslo and Paris Commission (OSPAR) Quality Status Reports (QSR2000) Home
Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP) Home
European Statistics (EuroStat) Home
Irish Marine Institute Home
Department of Agriculture and Rural Development Northern Ireland (DARDNI) Home
Irish Environmental Protection Agency (EPA) Home
Helsinki Commission (HELCOM) Home