L7 Flashcards
What does Dissolved Oxygen (DO) refer to?
The level of free, noncompound oxygen present in water
It is crucial for assessing water quality and the organisms within.
Why is dissolved oxygen important in aquatic ecosystems?
It influences the organisms living within a body of water
It is second only to water itself in importance.
What are the two common structures used by aquatic animals to acquire DO?
Gills and skin
What can cause a reduction in DO levels in water?
Addition of oxygen-consuming organic wastes
How does decomposition affect dissolved oxygen?
It can consume oxygen faster than plants can produce it, especially in hot conditions
How does oxygen enter a river?
By diffusion from the air and through photosynthesis
What factors affect the concentration of dissolved oxygen in water?
- Temperature
- Pressure
- Water clarity (turbidity)
- Current velocity (flow)
- Wind
- Cloud cover
How does temperature affect dissolved oxygen levels?
Warmer water holds less DO
An example is opening a soda bottle left in a hot car.
What is the Winkler method?
A titration method for measuring dissolved oxygen
What are the common nutrients required by aquatic species?
- Carbon (C)
- Nitrogen (N)
- Phosphorus (P)
Why is nitrogen essential for living organisms?
It is a component of proteins
What condition can excessive nitrate or nitrite concentrations in drinking water cause?
Methemoglobinemia (blue baby syndrome)
What is eutrophication?
The process where nitrogen and phosphorus lead to excessive algae growth, depleting dissolved oxygen
How does eutrophication reduce DO levels?
- Nitrogen feeds algae
- Algae grow and block sunlight
- Underwater plants die
- Decomposing algae consume oxygen
What are the adverse effects of eutrophication?
- Increased biomass of phytoplankton
- Toxic or inedible phytoplankton species
- Dissolved oxygen depletion
- Loss of desirable fish species
- Water treatment problems
