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Newsletter and Technical Publications
Lakes and Reservoirs vol. 3
Water Quality: The Impact of Eutrophication
Glossary
| Anoxia, anoxic conditions |
no oxygen present. |
| Biomanipulation |
Change in biological structure by removing and/or stocking
living organisms. |
| Chlorophyll a |
the green pigment in plants that promotes photosynthesis. |
| Epilimnion |
see Thermocline below. |
| Eutrophication |
nutrient rich. |
| External loading |
nutrients from outside the lake, for instance nutrients in
wastewater discharge to the lake, or nutrients from agricultural drainage water.
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| Hypolimnion |
See Thermocline below. |
| Internal loading |
nutrients from the lake itself, for instance release of
nutrients or toxic substances from the sediment (the muddy bottom layer) of the
lake. |
| Mechanical-biological treatment |
treatment of wastewater by settling of suspended matter together
with the use of microorganisms to decompose organic matter. Only minor amounts
of nutrients (nitrogen and phosphorus) are removed by this treatment. |
| Non-point pollution |
diffuse pollution mainly from agriculture or dumping grounds. It
is difficult to collect for treatment. |
| Photosynthesis |
formation of plant biomass from nutrients with solar radiation
as the energy source. |
| Phytoplankton |
free-floating microscopic plants. |
| Point pollution |
polluted water from a defined point. It can be collected as
industrial or municipal wastewater and treated by what is often called
end-of-pipe technology (environmental technology). |
| Sediment |
the bottom and often muddy layer of a lake. |
| Thermocline |
the level dividing a lake into two layers, an upper warmer one
(epilimnion) and a lower colder one (hypolimnion). The temperature usually drops
several degrees centigrade over just a few meters at this level. |
| Zooplankton |
microscopic to very small free-floating animals. |
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