Resources, Use, and Pollution Essential Question: What is the current and future status of our clean water supply? Day 1 1

Water Resources Humans use water for: 1 Water Resources Humans use water for: Drinking Agriculture Sanitation Travel Entertainment Essential for life – can go 3 weeks without food, but only 3 days without water Need freshwater! (not salt water) Day 1 2

Water Resources: Distribution 2 Water covers 2/3 of earth 97% of water on Earth is salt water in ocean & seas 2.5% is Frozen freshwater in glaciers 77% of all freshwater is frozen 0.5% is available freshwater on surface or in ground Day 1 3

Surface Water Surface H2O = lakes, rivers, streams, wetlands 3 Surface H2O = lakes, rivers, streams, wetlands Rivers especially important for human civilizations River system: flowing network of water that forms from streams Amazon*, Mississippi, Nile Watershed: area of land drained by a river Ex: Amazon River Basin Day 1 4

Water Cycle 4 Water is a Renewable Resource - circulated in the water (hydrologic) cycle: Evaporation (liquid → vapor in clouds) Condensation (vapor → liquid; in atmosphere) Precipitation (rain, sleet, snow) Surface Runoff (back to oceans) Note: can still deplete or ruin it Day 1 6

Groundwater Most available freshwater exists underground 5 Most available freshwater exists underground Groundwater: water beneath Earth’s surface in soil & rock Day 1 7

Groundwater 6 Aquifer: underground formation that contains lots of groundwater H2O is between rock, sand, & gravel Upper boundary of aquifer = water table Getting H2O depends on: Porosity: amount of space b/w rock & soil (H2O is stored in pores) Permeability: ability of rock or soil to allow H2O to flow Day 1 8

Groundwater How does water get to aquifer?: 7 How does water get to aquifer?: Recharge zone: area where H2O percolates down H2O must travel through permeable layers of soil Where aquifers are sensitive to pollution! Well: hole that is dug or drilled to reach groundwater in aquifer Must be below water table, or can dry up Day 1 9

Groundwater Groundwater Problems: Overdrawing – wells runs dry 7 Groundwater Problems: Overdrawing – wells runs dry Pollution: oil, chemicals, salt water Pavement prevents recharge Video: http://www.youtube.com/watch?v= uQRvN6MUajE Day 1 10

Different Types of Wells: Unconfined vs Different Types of Wells: Unconfined vs. Confined (artesian) Assignment: Draw On Paper & Color– Include All Words! 11

Water Use & Management Three major uses of H2O: Agriculture: irrigation Industries Residential – drinking & washing Day 2 Average person in US uses 300 L (80 gallons) / day 12

Water Use: Industrial Accounts for 19% of water used in world Used to manufacture goods dispose of waste Generate power Cool power plants Use & return water from lake or river → Thermal pollution?? Day 2 13

Water Use: Residential Use Water from toilet, dishwasher, bath, etc. enters sewers & must be treated Why Treat Water? Sewage: human wastes, paper, soap, detergent, food, bacteria, etc. Three-step process 2. 3. Day 2 5. 14

Water Treatment: 2. Secondary Treatment: 3. Tertiary Treatment: 1. Primary Treatment: Removes large solid objects (trash, diapers) & sand/grit 2. Secondary Treatment: Removes organic matter & kills microorganisms Oxygen is added for decomposition Is disinfected with chlorine to kill bacteria & viruses 3. Tertiary Treatment: = chemical or physical reactions to remove pollutants (phosphates, nitrates, salts, pesticides) Fluoride is added to drinking water 2. 3. Day 2 5. 15

Water Management Dam = structure built to control river flow; creates a reservoir = artificial lake Provides: Drinking water Irrigation water Recreation Hydroelectric dam: uses power of flowing water to turn turbine to generate electricity Problems with dams: flooding; prevents animal migration; pollution Day 2 16

Ways to Conserve Water: In Agriculture: Drip irrigation = water crops directly & little at a time In Industry: Recycle & reuse wastewater In Residential: Shorter & cooler showers Low-flow toilets Aerators in faucets Wash only full loads Day 2 17

Ways to Conserve Water: Future Solutions to Water Availability Issues: Desalination = process of removing salt from ocean water Expensive b/c of power requirements Towing Icebergs? - research says too costly Cloud Seeding - silver iodide crystals makes water droplets form if cloud is present Used in China Day 2 18

Water Pollution Water Pollution = when chemical, physical, or biological agents get into water and lowers quality & negatively affects organisms Two Types: Point-source Pollution = single source of pollution is known (one factory, one sewage treatment plant) Nonpoint-source Pollution = many different sources over a wide area -road chemicals -agricultural chemicals Day 3 19

Water Pollution Pollutants Include: Pathogens (bacteria, viruses, worms) Organic matter (feces, food waste, bodies) Chemicals (pesticides, oil, plastics, etc.) Heavy metals (lead, mercury, arsenic) Thermal pollution: Lowered water quality due to change in water temperature (influx of hot water) lowers levels of dissolved oxygen & can cause large fish kills Occurs next to power plants & factories Day 3 20

Water Pollution cont. Eutrophication: accumulation of nutrients in a lake or pond – natural process happens over time Artificial Eutrophication: increased amounts of nitrogen & phosphorus due to fertilizers speeds up plant growth and eventually choke the water of all of its animal life Day 3 21

Ground Water & Ocean Pollution Ground Water Pollutants: Surface water pollution Leaky storage tanks (gas, septic, chemicals) Landfills Difficult/ impossible to clean up Ocean Pollutants: Land runoff Oil spills Beach trash Day 3 22

Water Pollution & Ecosystems Biomagnification = build up of pollutants at higher levels of the food chain Examples: DDT enters body of zooplankton, a hundred of these organisms are eaten by a small fish, a hundred of these fish are eaten by a bigger fish, an eagle eats ten of these big fish, the concentration of DDT is magnified in the eagle Enters food chain → humans Day 3 23

Water Regulation Clean Water Act (1972) Other laws: Set goals for clean water; required metals to be removed from wastewater Other laws: Marine Protection, Research, & Sanctuaries Act (1972; 1988) – controlled dumping of sewage & toxic waste into water Safe Drinking Water Act (1975, 1996) – protects groundwater; standards for water quality Oil Pollution Act (1990) – all oil tankers must be double-hulled by 2015 24