Properties of Water: Universal solvent- dissolves more substances than any other liquid Water is polar: allows water molecule to be attracted to many different molecules Allows water to dissolve other substance Water 2 Types Fresh Water- you can drink; contains little salt Salt Water-oceans; high concentration of salt Exists in all forms: Solid, liquid, gas Renewable resource- circulates in water cycle Can become Nonrenewable-pollution destroys faster than it can be replenished Water Cycle Water by Numbers 71% of Earth is covered in Water 97% of Water on Earth is salt water 3 % Fresh water 77% Frozen 22% Groundwater 1% Other Surface Water Surface water- water on Earths land surface Lakes, rivers, streams, wetlands 2 categories: river systems & watersheds Uses: Drinking water Grow crops Power for industry Boat transportation Food-fish Surface Water- River Systems Where does water in a river or stream come from? Falling rain and melting snow-flows downhill Forms streams Stream combine with other streams-form rivers Forms river systems Examples: Mississippi River, Amazon, and Nile River Amazon river- Largest river system in world Surface Water-Watersheds Watersheds-area of land that is drained by a river Amount of water that enters watershed varies Melting snow and rain-increase watershed Other times of year may have decrease in water in watershed Communities dependent on rivers can be affected by these changes Groundwater water stored beneath the Earths surface in sediment & rock formations Water table Water travels beneath surface and reaches a level where the rocks and soil are saturated Aquifers Water table forms the upper boundary of an aquifer- an underground formation that contains groundwater Aquifers contain rock, sand, and gravel- water can accumulate in the spaces Holds about 4 quadrillion liters of water Formed from glaciers that melted thousands of years ago. What is the aquifers primary water source today? How can a rock formation hold millions of gallons of water? Rock contain pores-small holes Porosity- amount of space between particles in a rock The more porous, the more water it holds Permeability the ability of water to flow through rock or soil Permeable and impermeable Reaching Aquifers Water must reach aquifers by percolating through permeable substances- this area is called the recharge zone To reach water in an aquifer, you must drill a well Global Water Use 3 Major uses: Residential use Agricultural use Industrial use What factors effect how water is used? Availability of fresh water Population size Economic conditions Residential Water Use Water that is used for: Drinking Cooking Washing Toilet flushing Watering lawns Washing cars Averages: US: 300 L/day for average person India: 41 L/day for the average person Water Treatment Water must be treated to make it potable: safe to drink Industrial Water Use 19% of water used in the world Used to: Manufacture goods Dispose of waste Generate power Cool power plants Agricultural Water Use 67% of water used in the world Plants require A LOT of water to grow 300 L to grow one ear of corn Irrigation-used for regions with little rain provides plants with water from other sources than precipitation (rain) Water conservation As water sources become depleted, water becomes more expensive Wells have to be dug deeper, piped greater distances, and polluted water must be cleaned Conserving water= more water for reasonable price Ways to conserve Drip irrigation systems- in agriculture-delivers water directly to plant roots Recycle cooling water and waste water in industry Conserving water in the home: Take shorter showers Low flow showerheads Dont let water run while brushing teeth Desalination- removing salt from salt water Transporting water from different regions of the world Towing icebergs- not an efficient way yet What is water pollution? Water pollution cant always been seen or smelt There are many different forms of water pollution The introduction of chemical, physical, or biological agents into water that degrade water quality and adversely affect the organisms that depend on the water Types of pollution To prevent pollution, people must understand where pollutants come from: Point-source pollution Comes from a single source Nonpoint-source pollution Comes from many different sources Point-source Pollution Leaking septic tank Unlined landfills Leaking underground storage tanks that contain chemicals or fuels such as gasoline Water discharged by industries Public and industrial waste-water treatment plants Nonpoint-Source Pollution Chemicals added to road surfaces (salt and other de- icing agents) Water runoff from city and suburban streets that contain oil, gas, animal feces, and litter Pesticides, herbicides, and fertilizer from lawns, golf courses, and farmland Types of Water Pollution Waste water Water that contains waste from homes or industry Artificial Eutrophication Eutrophication-adding nutrients to water; natural process Accelerated by inorganic nutrients such as phosphorus and nitrogen from fertilizer or sewage runoff This is called artificial eutrophication; can cause alga blooms Thermal pollution Body of water increases in temperature Caused by power plants discharging warm water into lakes/rivers Can kill organisms Groundwater pollution Pesticides Herbicides fertilizers Ocean pollution Oil spills Water pollution & Ecosystems Pollution can accumulate in the environment because they do not decompose quickly Accumulation of pollution at successive levels of the food chain-biomagnification Your Pee is Pollution Cleaning up Water Pollution 1972: Clean Water Act Opened the door for water quality legislation Banned pollutant discharge into surface water Required that metals be removed from wastewater