Env Ch15b

• •Once the fourth-largest lake on Earth
• -It has lost more than 80% of its volume in just 45 years
• The two rivers leading into the Aral Sea were diverted to irrigate cotton fields
• •Consequences of a shrinking sea
• 60,000 fishing jobs are gone
• Pesticide-laden dust from the lake bed is blown into the air
• The cotton cannot bring back the region’s economy
• 

the removal of salt from seawater or other water of marginal quality

hastens evaporation and condenses the vapor

forces water through membranes to filter out salts

landscaping using plants adapted to arid conditions

• Water for human consumption and other organisms needs to be…
• Disease-free
• Nontoxic

the release of matter or energy into the environment that causes undesirable impacts on the health and well-being of humans or other organisms

• Phosphate-free detergents
• Planting vegetation to increase nutrient uptake
• Treat wastewater
• Reduce fertilizer application

• Enters water supply via inadequately treatedhuman waste and animal waste via feedlot
• Causes more human health problems than any other type of water pollution
• Fecal coliform bacteria indicate fecal contamination of water
• -The water can hold other pathogens, such as giardiais, typhoid, hepatitis A

• Currently, 1.1 billion people are without safe drinking water
• 2.4 billion have no sewer or sanitary facilities
• Mostly rural Asians and Africans
• An estimated 5 million people die per year

• -Clear-cutting, mining, poor cultivation practices
• -Dramatically changes aquatic habitats, and fish may not survive
• -Solutions: better management of farms and forests; avoid large-scale disturbance of vegetation

• •Warmer water holds less oxygen
• -Dissolved oxygen decreases as temperature increases
• -Industrial cooling heats water
• -Removing streamside cover also raises water temperature
• •Water that is too cold causes problems
• -Water at the bottom of reservoirs is colder
• -When water is released, downstream water temperatures drop suddenly and may kill aquatic organisms

• •discrete locations of pollution
• -Factory or sewer pipes

• •pollution from multiple cumulative inputs over a large area
• -Farms, cities, streets, neighborhoods
• •The U.S. Clean Water Act
• -Addressed point sources
• -Targeted industrial discharge
• In the U.S., nonpoint sources have a greater impact on quality
• -Limit development on watershed land surrounding reservoirs

the physical removal of contaminants in settling tanks (clarifiers)

water is stirred and aerated so aerobic bacteria degrade organic pollutants