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STRATIFICATION IN LAKES 
CENTER FOR BIOTECHNOLOGY AND 
MICROBIOLOGY 
PRESENTED BY 
ADAM KHAN C# 3 4 
7 TH SEMESTER 
1
INTRODUCTION OF LAKES 
A lake is an area, filled with fresh or salt water of 
considerable size,localized in a basin, that...
TYPES OF LAKE 
There are two types of lakes 
 Eutrophic lakes 
Those that are shallow, saucer-like ones called eutrophic ...
EFFECTS OF EUTROPHICATION 
Oligotrophic 
Low biomass 
High diversity 
Complex food web 
Oxic waters 
Cold-water fish pres...
DARAL LAKE VALLEY LALKOO 
LAKE 
5
STABILITY OF LAKE STRATIFICATION 
 Stable stratification results when waters of differing densities are 
positioned verti...
THERMAL ZONES IN A STRATIFIED 
LAKE 
6 8 10 12 14 16 18 20 22 24 26 
Temperature oC 
Depth (m) 
0 
1 
2 
3 
4 
5 
6 
7 
8 ...
LAKE COLOR 
Scattering and absorption of light 
give lake part of its characteristic 
color 
Clean water - blue color 
Mor...
STRATIFICATION OF LAKES 
Lake divided vertically into 3 regions 
Epilimnion 
Metalimnion(thermocline) 
Hypolimnion 
9
 Epilimnion –top of the lake 
uniformly warm layer mixed by wind 
 Metalimnion – middle layer 
Intermediate zone where t...
HYPOLIMNION 
THE BOTTOM LAYER. 
 uniformly cool lower layer unaffected by wind 
11
12
CHEMISTRY OF LAKES - OXYGEN 
o Oxygen is the second most abundant element in the 
atmosphere (20%) 
But is only weakly sol...
LAKE CHEMISTRY - OXYGEN 
Sources 
 Atmosphere 
Photosynthesis 
o 6CO2 + 6H20 + light C6H12O6 + O2 
Sinks 
Respiration 
Ch...
NUTRIENT LIMITATION 
The growth of algae and higher aquatic plants in lakes is 
regulated by conditions of light and tempe...
16
LAKE CLASSIFICATION BY 
CIRCULATION 
• Amixis refers to a lake that does not ever turnover; called an 
amictic lake. 
• Ho...
• MONOMICTIC LAKES TURNOVER ONCE. 
Cold monomixis: 
colder lakes that 
inverse stratify 
only under 
winter ice cover 
and...
MICROBIAL FAUNA IN LAKES 
 Microbes include bacteria, bacteria-like organisms called 
archaea, viruses, protozoa, helmint...
THANKS 
20
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Lake

stratification in lakes

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Lake

  1. 1. STRATIFICATION IN LAKES CENTER FOR BIOTECHNOLOGY AND MICROBIOLOGY PRESENTED BY ADAM KHAN C# 3 4 7 TH SEMESTER 1
  2. 2. INTRODUCTION OF LAKES A lake is an area, filled with fresh or salt water of considerable size,localized in a basin, that is surrounded by land. 2
  3. 3. TYPES OF LAKE There are two types of lakes  Eutrophic lakes Those that are shallow, saucer-like ones called eutrophic lakes  Oligotrophic lakes usually, turbid water and deep, steep-sided ones called oligotrophic lakes with clear water. 3
  4. 4. EFFECTS OF EUTROPHICATION Oligotrophic Low biomass High diversity Complex food web Oxic waters Cold-water fish present High aesthetic quality No taste or odor problems Eutrophic High biomass Low diversity Simple food chain Anoxic bottom waters Cold-water fish absent Low aesthetic quality Taste and odor problems Rough fish abundant Toxic algae present 4
  5. 5. DARAL LAKE VALLEY LALKOO LAKE 5
  6. 6. STABILITY OF LAKE STRATIFICATION  Stable stratification results when waters of differing densities are positioned vertically in order of their density  In other words, more density (heavier) water lies below less dense (lighter) water  Energy is required to break down this density gradient  Stability of stratification is the energy required to uniformly mix a stratified lake. 6
  7. 7. THERMAL ZONES IN A STRATIFIED LAKE 6 8 10 12 14 16 18 20 22 24 26 Temperature oC Depth (m) 0 1 2 3 4 5 6 7 8 9 10 11 12 7
  8. 8. LAKE COLOR Scattering and absorption of light give lake part of its characteristic color Clean water - blue color More and bigger particles scatter longer wavelengths and absorb shorter wavelengths Blue-green, green, yellow 8
  9. 9. STRATIFICATION OF LAKES Lake divided vertically into 3 regions Epilimnion Metalimnion(thermocline) Hypolimnion 9
  10. 10.  Epilimnion –top of the lake uniformly warm layer mixed by wind  Metalimnion – middle layer Intermediate zone where temperature drops rapidly with increasing depth  Also referred to as thermocline - plane between two depths between which temperature change is greatest . 10
  11. 11. HYPOLIMNION THE BOTTOM LAYER.  uniformly cool lower layer unaffected by wind 11
  12. 12. 12
  13. 13. CHEMISTRY OF LAKES - OXYGEN o Oxygen is the second most abundant element in the atmosphere (20%) But is only weakly soluble in water (10 ppm) o Most aquatic organisms require 4-5 mg/L for survival So… oxygen can be a limiting factor in aquatic systems The absence of oxygen can allow other chemicals like H2S to build up. 13
  14. 14. LAKE CHEMISTRY - OXYGEN Sources  Atmosphere Photosynthesis o 6CO2 + 6H20 + light C6H12O6 + O2 Sinks Respiration Chemical oxidation Gas bubbles 14
  15. 15. NUTRIENT LIMITATION The growth of algae and higher aquatic plants in lakes is regulated by conditions of light and temperature and the availability of those inorganic nutrients required to support growth. The element most often in limiting supply is phosphorus, P. 15
  16. 16. 16
  17. 17. LAKE CLASSIFICATION BY CIRCULATION • Amixis refers to a lake that does not ever turnover; called an amictic lake. • Holomixis refers to lake turnover. The frequency of mixis over annual to decadal time scales is used in classifying lakes. • Dimictic lakes follow the pattern described for temperate lakes; spring and fall turnovers. • Oligomictic lakes turnover every few years. – . 17
  18. 18. • MONOMICTIC LAKES TURNOVER ONCE. Cold monomixis: colder lakes that inverse stratify only under winter ice cover and mix the remainder of the year. Warm monomixis: warmer lakes that mix during winter (never freeze over) and stratify in summer. 18
  19. 19. MICROBIAL FAUNA IN LAKES  Microbes include bacteria, bacteria-like organisms called archaea, viruses, protozoa, helminths, and protists. Cyanobacteria are an important group of plants often appearing a dominant part of the phytoplankton of lakes and reservoirs. They tend to form a dense surface bloom rising to the surface 19
  20. 20. THANKS 20

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