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Questions and Answers
Which of these zones includes the presence of fish and normal levels?
Which of these zones includes the presence of fish and normal levels?
What occurs in the Decomposition Zone?
What occurs in the Decomposition Zone?
Dissolved oxygen levels go down as aerobic bacteria consume sewage matter.
What happens to fish in the Septic Zone?
What happens to fish in the Septic Zone?
Fish are absent due to the presence of hydrogen sulfide and lack of oxygen.
What characterizes the Recovery Zone?
What characterizes the Recovery Zone?
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The ______ is the final stage where chemical levels return to normal if no sewage is input.
The ______ is the final stage where chemical levels return to normal if no sewage is input.
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Anaerobic bacteria are usually more abundant than aerobic bacteria in clean, highly oxygenated water.
Anaerobic bacteria are usually more abundant than aerobic bacteria in clean, highly oxygenated water.
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What is the main role of dissolved oxygen in water?
What is the main role of dissolved oxygen in water?
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Study Notes
Oxygen Sag Curve Zones
- Order of Zones: Clean Zone, Decomposition Zone, Septic Zone, Recovery Zone, Clean Zone (end).
Clean Zone
- Characterized by the presence of fish and normal levels of oxygen and chemicals.
Decomposition Zone
- Decreasing dissolved oxygen (DO) levels due to an increased biochemical oxygen demand (BOD) as aerobic bacteria consume sewage.
- Aerobic bacteria significantly lower DO through respiration; below 2 ppm DO, bacteria begin to suffocate.
Septic Zone
- Anaerobic bacteria proliferate, consuming the remaining sewage.
- Hydrogen sulfide produced as a byproduct of anaerobic respiration; this compound is highly toxic.
- Fish are absent, with only macroinvertebrates like sludge worms surviving due to oxygen depletion.
Recovery Zone
- Once sewage is decomposed, anaerobic bacteria die off from food scarcity.
- Aerobic bacteria start to recover, leading to the replenishment of DO and a decrease in BOD.
Clean Zone (end)
- Resumption of normal chemical and organism levels occurs, provided there is no new sewage input.
Anaerobic vs. Aerobic Bacteria
- Anaerobic bacteria population is typically much smaller compared to aerobic bacteria in clean, well-oxygenated waters.
Dissolved Oxygen
- DO is continuously replenished through diffusion and wave action across all zones, although bacteria rapidly consume it.
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Description
Explore the key concepts and terminology of the Oxygen Sag Curve with these flashcards. Each card offers a detailed definition and explanation of important zones related to dissolved oxygen levels in water bodies. Test your understanding and reinforce your knowledge in environmental science.