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Human Impact on water
Water Cycle Review
- Also called the hyrological cycle
- The journey water takes as it circulates from the land to the air and back again.
- Involves evaporation, condensation, and precipitation.
- Repeats as a never ending cycle.
Natural Resource
- Naturally occurring substances such a mineral, forest, water, and land that are used by humans.
- A resource that can be used repeatedly because it is replaced naturally (cycle).
- Water fits both these criteria
Watershed
- Basin-like land formation defined by high points and divides that descends into lower elevations.
- Carries water from the land after rainfall or snow melts.
- Drains all the water into a common outlet such as a stream channel, a reservoir, or bay
Freshwater
- Very low amounts of dissolved salt – less than 1%
- Examples:
- Ponds and Lakes
- Streams and Rivers
- Wetlands
- Ponds and Lakes
- Makes up 3% of Earth’s water resources, including ice caps and glaciers
Saltwater
- High concentrations of salt
- 3.5% of the weight of seawater comes from dissolved salt (salinity)
- Examples:
- Oceans
- Seas
- Makes up 97% of Earth’s water resources
Surface Water
- Water on the surface of the planet
- Examples:
- Ponds and Lakes
- Streams and Rivers
- Wetlands
- Oceans
- Ponds and Lakes
- Replenished by precipitation and groundwater
- More prone to pollution than groundwater
Groundwater
- Water found underground in cracks and spaces in soil, sand, and rock.
- Stored in and moves slowly through aquifers
- More than 50% of the people in the U.S. get their drinking water from groundwater.
- Largest use is irrigating crops
- Less prone to pollution
Groundwater Vocabulary
Aquifers
- Found underground
- Made of gravel, sand, sandstone, or limestone
- Water can move through these materials because they have large connected spaces (pores) that make them permeable.
- The flow of water depends on the size of the spaces and how well they are connected.
Well
Water Pollution
- Contamination of bodies of water, often by human activity, which affects watersheds
- Occurs when pollutants are discharged directly or indirectly into the water.
- Along with air pollution, water pollution is the second biggest environmental concern.
Point Source Pollution
- When the pollutants come from a single location such as dumping chemicals into a river.
Non Point Source Pollution
- When pollutants are introduced into the environment over a large, widespread area such as agricultural runoff.
Surface Water Pollution
- Hazardous substances coming into contact with surface water
- Dissolves or mixes physically with the water
- Examples: Humans dumping trash into the waterways, especially objects that are swept down storm drains.
- Also, sewage
Oil Pollution
- Release of liquid petroleum hydrocarbons (oil) into the water
- Especially harmful to marine and other wildlife
- Usually localized, but can spread
- Examples: oil spills
Chemical Water Pollution
- Chemicals from industries and farmers that run off into the waterways.
- Examples: metals and solvents from industries
- Also, chemicals that control weeds, insects, and pests
Groundwater Pollution
- Pesticides and chemicals wash deep into the ground by rain water
- Can get into the aquifers, thus polluting the groundwater
- Anything on the surface can eventually work its way down to the groundwater.
- Plume – the area of groundwater affected by the contamination
- Look at the diagram and observe the amount of contamination in relationship to the point pollution.
Thermal Water Pollution
- The rise or fall in the temperature of a natural body of water.
- Changes the physical properties of water, particularly the amount of dissolved oxygen in the water.
- Decreases fish population and increases death to wildlife
Agricultural Pollution
- Sediments washing off fields are the largest source of agricultural pollution in the U.S.
- Sediments increase the cost of treating drinking water and can also clog fish gills, reducing their resistance to disease.