unit 8 Flashcards
the final show, cream cheese
What is BOD?
Biochemical Oxygen Demand — it measures how much oxygen bacteria use to break down waste in water.
What does high BOD mean?
It means the water is polluted. More waste = more bacteria = more oxygen used = less oxygen for fish.
How do streams handle pollution?
Streams can recover because the water flows and mixes, but if there’s too much pollution, oxygen levels drop and fish can die.
What is eutrophication?
Too many nutrients (like nitrogen and phosphorus) cause algae to grow a lot, which uses up oxygen when the algae dies, killing fish.
What causes cultural eutrophication?
Human actions — like fertilizer runoff, sewage, or farm waste — add nutrients to water and speed up algae growth.
What is a Dead Zone?
An area in water with almost no oxygen, usually caused by algae blooms and decomposition. Fish and other life can’t survive there.
How can arsenic be removed from water?
By using special filters, reverse osmosis, or chemicals (like iron) that bind to arsenic and remove it.
Why is the Chesapeake Bay in trouble?
Nutrient pollution from farms and cities caused algae blooms, which led to low oxygen and fish kills. Efforts are underway to clean it up.
How do septic systems work?
Wastewater flows into a tank where solids settle. The liquid goes into the ground and gets naturally filtered through the soil.
Why is thermal pollution bad?
Warm water holds less oxygen and can stress or kill fish. It also messes with their metabolism and breeding.
Clean Water Act vs Safe Drinking Water Act?
Clean Water Act protects lakes, rivers, and other surface water. Safe Drinking Water Act makes sure your tap water is safe to drink.
What are POPs (Persistent Organic Pollutants)?
Toxic chemicals (like DDT) that last a long time, build up in organisms, and move up the food chain, causing health problems.
What is the hydrologic cycle?
The movement of water through evaporation, condensation, precipitation, infiltration, and runoff — nature’s water recycling system.
What is an aquifer?
Underground rock or sediment that holds water — like a sponge under your feet.
What’s the difference between confined and unconfined aquifers?
Confined aquifers are trapped between layers and under pressure. Unconfined aquifers are closer to the surface and easier to pollute.
What is the water table?
The top of the groundwater layer — below this line, the soil is fully soaked with water.
What is the Ogallala Aquifer and why is it important?
It’s the largest aquifer in the U.S. Used mostly for farming, but it recharges super slowly and is being drained too fast.
What is subsidence?
When land sinks because too much groundwater is removed, leaving empty space underground.
What is saltwater intrusion?
When ocean water seeps into freshwater aquifers, usually near coasts, making the water salty and unusable.
What is greywater recycling?
Reusing water from sinks, showers, or laundry for things like watering plants or flushing toilets — saves clean water.
