Chapter 11 Environmental Science Water Chapter 11 Environmental Science

Water Resources Section 11.1

The Water Cycle Water Cycle: water molecules circulating between the Earth’s surface and the atmosphere. It involves condensation, evaporation, transpiration, and precipitation.

Global Water Distribution 71% of the Earth’s surface is covered in water 97% of that water is salt water in ocean and seas 77% of the fresh water on Earth is frozen in icecaps and glaciers Fresh water is a limited resource because there is only about 3% usable freshwater.

Surface Water Surface Water: Is fresh water on Earth’s land surface. Lakes, streams, rivers, and wetlands. Water is used for drinking, agriculture, power, and transportation.

River Systems vs. Watersheds River are formed by: Rain and snow draining down from mountains and hills. Small streams come together to form rivers A 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.

Groundwater Ground water: water beneath the Earth’s 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.

Aquifers Aquifer: 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.

Porosity vs. 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 hold The ability of rock or soil to allow water to flow through it. Example: granite, sandstone, and limestone are permeable but clay is impermeable.

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

Wells Well: 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.

That is all of 11.1 Time for a reading quiz.

Water Use and Management Section 11.2

Global Water Use Residential (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)

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

Water Management Projects Aqueducts or huge canals are used to bring water from mountains to dry areas. Reservoirs or artificial lakes are used for recreation or drinking water Dams are structures built across a river to control the river’s flow.

Benefits and Consequences of Dams Flood control Drinking water Irrigation Recreation Industry Electrical energy People can be displaced Entire ecosystems can be destroyed Farmland below dam becomes less productive Dam failure can lead to death.

Water Conservation Agriculture: drip irrigation systems Industry: recycling of cooling water and wastewater Residential: shorter showers, low-flow toilets/showers, turn water off when brushing teeth, wash full loads, and water lawns sparingly.

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

That is all for 11.2 Time for a reading quiz.

Water Pollution Section 11.3

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

Two Sources of Water Pollution Point-Source Pollution Nonpoint-Source Pollution Comes from many different sources Difficult to identify and trace. Examples: road or agricultural runoff, polluted precipitation, water runoff. Pollution discharged from a single source. Easier to identify and trace. Examples: leaking tank or unlined landfill.

Physical Water Pollutants Pathogens: disease causing organisms Organic matter: feces, food wastes Organic chemicals: pesticides, fertilizers, plastics Inorganic chemicals: acids, bases, salts Heavy metals: lead, mercury, cadmium, arsenic Physical agents: heat and suspended solids

Wastewater Wastewater: 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 treatment Hard to dispose of so sludge can be used for fertilizer and to make bricks.

Artificial Eutrophication Eutrophication 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.

Thermal Pollution Thermal 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.

Groundwater Pollution Groundwater 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

Cleaning Up Groundwater Pollution Why it’s a challenging problem: Aquifers recharge very slowly Pollution can cling to the materials that make up an aquifer

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

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

Cleaning up Water Pollution Clean 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 chemicals Safe Drinking Water Act (1975):to protect groundwater/surface water from pollution Comprehensive 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.

That is all for 11.3 Time for a reading quiz