6.12 – NOTES Water

2 water related challenges faced every day- Can we get enough water? Is the water pure enough?

Purity is a relative term 100% pure water is impossible in a municipal system Cost – very expensive to remove everything Dissolved Gases – gases dissolve very easily and are hard to get out What are some other impurities that may be found in water? Disinfecting agents, mud, trash, skin, algae, fish, sticks

It takes approximately 120 L of water to produce one 1 It takes approximately 120 L of water to produce one 1.3 L can of fruit juice. It takes about 450 L of water to place one fried egg on your breakfast plate. Think of possible explanations for these two facts. Direct vs Indirect uses of water Direct – measureable Indirect – Can’t Measure

How do we purify water? Filtration Process of separating solid particles from a liquid by using a membrane Filtrate Liquid left after filtration; residue = solid particles Adsorption Attraction of impurities to the surface of something ; charcoal absorbs odor and color Percent recovery % of purified water recovered at the end of the purifying process % recovery = final volume initial volume x 100  

Pure and Impure Water Why is it useless to get water that is 100% pure? Very expensive It’s hard to remove trace amounts of metals and other ions from water

Water Supply and Demand 15 trillion L (4 trillion gallons) of precipitation falls in the US each day 10 % of this is used by humans  

Average family of 4 uses 1200 L of water/day Direct use only Use that can be directly measured Indirect use - can’t be directly measured   We are generally unaware of how much water we actually use each day Anecdote about my water situation

Where is the World's Water? Water is unusual due to the fact that it exists as all 3 states (solid, liquid, gas) at normal conditions   Most of the US has abundant supplies of water Surface water- water that is exposed to the atmosphere, rivers, lakes, streams, oceans, etc

Groundwater- must be pumped to the surface to be used; in wells  1/5 of all water is groundwater Aquifer- water holding layer of rock, sand, or gravel that is a holding are for groundwater  

The majority of water must be purified before being used Picks up dissolved gas, rocks, soil as it travels through the ground/pipes   Where is it? 97.2%- oceans 2.8%- freshwater 2.11%- glaciers/ice caps 0.62%- groundwater 0.009%- lakes 0.001%- atmospheric moisture 0.0001%- rivers