Water

WaterChapter 11Environmental Science

1Water ResourcesSection 11.1

2The Water CycleWater Cycle: water molecules circulating between the Earths surface and the atmosphere.It involves condensation, evaporation, transpiration, and precipitation.

3Global Water Distribution71% of the Earths surface is covered in water97% of that water is salt water in ocean and seas77% of the fresh water on Earth is frozen in icecaps and glaciersFresh water is a limited resource because there is only about 3% usable freshwater.

4Surface WaterSurface Water: Is fresh water on Earths land surface.Lakes, streams, rivers, and wetlands.Water is used for drinking, agriculture, power, and transportation.

5River Systems vs. WatershedsRiver SystemsWatershedsRiver are formed by:Rain and snow draining down from mountains and hills.Small streams come together to form riversA river system is a flowing network of surface water.Amazon is largest river system.What is a watershed: The area of land that is drained by a river.Pollution in a watershed can pollute the river.Amount of water varies depending on precipitation and melting snow.

6GroundwaterGround water: water beneath the Earths surface in sediment and rock formations.Water table is where rock and soil are saturated with water.Water table varies in wet regions vs. dry regions.

7AquifersAquifer: an underground formation that contains groundwater.Consist of rock, sand, and gravel where water can accumulate.It is an important water source for many cities and for agriculture.

8Porosity vs. PermeabilityPorosity :Permeability:Is the percentage of the total volume of a rock that has spaces or pores.The more porous a rock, the more water it can holdThe ability of rock or soil to allow water to flow through it.Example: granite, sandstone, and limestone are permeable but clay is impermeable.

9The Recharge ZoneRecharge Zone: An area of the Earths surface from which water percolates down into an aquifer. Water enters an aquifer through the aquifers recharge zone.Environmentally sensitive because of pollutants.Size is affected by permeability of the surface above the aquifer. They can be blocked by structures.

1010WellsWell: a hole that is dug or drilled to reach groundwater.Are drilled to extend below water table.Droughts and removing groundwater faster than it is recharged leads to wells drying up.

11That is all of 11.1Time for a reading quiz.

12Water Use and ManagementSection 11.2

13Global Water UseResidential (drinking, washing, cooking, toilets)Industrial (manufacture goods, dispose of waste, and generate power)Agricultural (most of the fresh water used worldwide is used to irrigate crops)

14Water TreatmentWater is treated physically and chemically to make it potable or safe to drinkMercury, arsenic, and lead are removed by adding chlorine.Pathogens: organisms that cause illness or disease are also removed.

15Water Management ProjectsAqueducts or huge canals are used to bring water from mountains to dry areas.Reservoirs or artificial lakes are used for recreation or drinking waterDams are structures built across a river to control the rivers flow.

16Benefits and Consequences of DamsBenefitsConsequencesFlood controlDrinking waterIrrigationRecreationIndustryElectrical energyPeople can be displacedEntire ecosystems can be destroyedFarmland below dam becomes less productiveDam failure can lead to death.

17Water ConservationAgriculture: drip irrigation systemsIndustry: recycling of cooling water and wastewaterResidential: shorter showers, low-flow toilets/showers, turn water off when brushing teeth, wash full loads, and water lawns sparingly.

18Solutions for the futureDesalinization: removing salt from salt water. (very expensive)Transporting water: ships transfer bags of fresh water or towing icebergs. (hard to find efficient way)

19That is all for 11.2Time for a reading quiz.

20Water PollutionSection 11.3

21Water PollutionWater pollution: the introduction of chemical, physical, or biological agents into water.Two causes are industrialization and rapid human population growth.

22Two Sources of Water PollutionPoint-Source PollutionNonpoint-Source PollutionPollution discharged from a single source.Easier to identify and trace.Examples: leaking tank or unlined landfill.Comes from many different sourcesDifficult to identify and trace.Examples: road or agricultural runoff, polluted precipitation, water runoff.

23Physical Water PollutantsPathogens: disease causing organismsOrganic matter: feces, food wastesOrganic chemicals: pesticides, fertilizers, plasticsInorganic chemicals: acids, bases, saltsHeavy metals: lead, mercury, cadmium, arsenicPhysical agents: heat and suspended solids

24WastewaterWastewater: water that contains waste from homes or industry.Most wastewater can be treated but some toxic substances require further treatment.Sewage sludge is the solid material that remains after treatmentHard to dispose of so sludge can be used for fertilizer and to make bricks.

25Artificial EutrophicationEutrophication is when phosphates and nitrates enter the water from sewage and fertilizer runoff.Can be caused naturally or by humans.Causes algal blooms that eventually die and causes the water to becomes oxygen depleted.

26Thermal PollutionThermal pollution: when the temperature of a body of water increases.When power plants use water in their cooling systems and then discharge warm water back into lake or river.Causes large fish kills and aquatic organisms suffocate.

27Groundwater PollutionGroundwater pollution: when polluted surface water percolates down.Pesticides, fertilizers, and petroleum are groundwater pollutants.Other sources: leaking underground water tanks, septic tanks, and unlined landfills

28Cleaning Up Groundwater PollutionWhy its a challenging problem:Aquifers recharge very slowlyPollution can cling to the materials that make up an aquifer

29Ocean PollutionDumped wastewater and garbage pollute the ocean.Majority of pollution caused by land activitiesOil spills (37 million gals)More oil enters from nonpoint sources in cities and towns (200-300 million gals)

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Water Pollution and EcosystemsWater pollution: can have immediate effects or lead to biomagnification. biomagnification: the buildup of pollutants at higher levels as it travels up the food chain.

31Cleaning up Water PollutionClean Water Act (1972): make all surface water fit for fishing/swimming by 1983.Marine Protection, Research and Sanctuaries Act (1972): to control the dumping of sewage waste/toxic chemicalsSafe Drinking Water Act (1975):to protect groundwater/surface water from pollutionComprehensive Environmental Response and Compensation and Liability Act (1980): makes owners/operators/customers of hazardous waste responsible for the clean up.Water Quality Act (1987): support state and local effort to clean polluted runoff. Oil Pollution Act (1990): protects US waterways from oil pollution.

32That is all for 11.3Time for a reading quiz33