Environmental Science CHAPTER 20

 “Water, water, everywhere, nor any drop to drink” – The Rime of the Ancient Mariner

Water  300 Liters – average US person daily usage  Personal hygiene and home cleaning  Small amount of 300 Liters – cooking and cleaning  40 Liters – lawn sprinkler use every minute

 15,000L of water to get the steel used to make one washing machine  Availability of water WON’T effect where companies locations are?  True or False?  Irrigation - Process of bringing water to an area for use in growing crops  Irrigation increases crop yield

 9% of water is used by?  Residential  44% of water is used by?  Industrial  47% of water is used by?  Agriculture

Define  Flood Irrigation:  Flooding of an area land that is flat. It is wasteful because most of the water drains into soil  Furrow Irrigation:  Releases water into furrows, or ditches, dug between rows of crops. It’s used in flat areas evaporation rate is high and mineral salts accumulate quickly

Define  Overhead Irrigation:  Sprinkler systems. Drip, or trickle irrigation. Less efficient as winds increase  Subirrigation:  Water is introduced naturally or artificially beneath the soil

Effects of Water Use on Ecosystems  Mono lake to other areas  Mono Lake is a saltwater lake fed by streams that carry meltwater rich in dissolved minerals from surrounding mountains  No outlet – salts are left behind from evaporation  Humans began reverting meltwater for use; no water added to Mono Lake  A major rise in salt

Water Resources 20.2

Surface Water and Aquifers  Runoff - is the water that does not seep into the ground, but instead flows down a slope over land.  Rills - are shallow grooves that are carved from runoff  Soil water - is water that fills the spaces between soil particles  Joints - layers of bedrock beneath the soil that is full of cracks

 Ground water – is the water within porous or jointed bedrock  A water table is the top of the saturated layer of rocks  Zone of Saturation - The saturated rock layer beneath the water table. Also know as an aquifer  Zone of Aeration - The area where groundwater enters an aquifer  Zone of Discharge – The area where groundwater leaves the aquifer and becomes surface water

Water Resource Problems  Overdraft – when a body of water is drained faster than it is filled  Two main problems with overdraft:  Saltwater intrusion – when saltwater intrudes into inland freshwater bodies, soil, and bedrock  Subsidence – when bedrock is weakened by the removal of freshwater from underground aquifers  Fig – Ogallala Aquifer

Water Treatment 20.3

Water  Tap water is not considered safe to drink in much of South America, Mexico, China, and parts of Africa.  A large supply of fresh water is essential to a nation’s development. Fresh water areas may not be able to support their human populations or the populations of other organisms.

Water  Penguins can tolerate the high concentration of salt in ocean water because they have special glands that remove the salts. Most organisms do no have such adaptations.

Desalination  The process by which salts are removed from water is called DESALINATION.  Desalination can be used to obtain fresh water for drinking, cooking, and irrigation. It also can be used to remove salt from agricultural waste water. For example, high concentrations of salt in the water of Colorado were killing the crops in Mexico.

Distillation  Salt water is heated to boiling  Water is evaporated and salt remains  Water vapor is cooled and fresh water collected

Reverse Osmosis  Salt water is forced through a strainer that traps the salt and lets the fresh water pass. The strainer is a thin membrane with tiny pores. The pores are large enough for water to pass through but too small for the salt.

Freezing  Salt water is frozen  As it freezes, salt and water separate  Fresh water is frozen and brine slush is secreted  Almost 1 million L of fresh water each day – Wrightsville Beach, North Carolina

Water Purification  The treatment of fresh water for the removal of minerals along with water treatment  Purification removes harmful chemicals and microorganisms which would usually make water unpotable  Several Processes:  Sedimentation  Filtration  Aeration  Sterilization

Sedimentation and Filtration  These processes use a series of screens to trap debris and other particles  Water is allowed to stand and over time, sediments settle to the bottom of the tank and purer water is left on top  COAGULANTS – chemicals added to the water to aid in the settling process (causes finer particle to clump together)  Water is then filtered through a 1M layer of sand for final purifying

Aeration and Sterilization  Water that has undergone Sedimentation and Filtration it can still have undesirable traits such as bad odor or taste due to dissolved gases  Aeration – the exposure of water to air  Any bacteria or microorganisms introduced during this process are killed using sterilizing chemicals such as chlorine and ozone which are very effective

 True  Water purification removes harmful chemicals from the water.  Aeration is the exposure of water to air and sunlight.  True.

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