11/1/10Freshwater- less than 1% salt- By 2050, 1/3 of all people on earth will lack access to freshwater- 70% of earth’s surface is water, but only 2.5% of that whole is freshwaterWhere?- 60% in glaciers and ice caps- 10% is found in surface waters, including lakes and rivers- 30% is found in groundwater, but some of it is deep and out of reachWater Use- 70% used for agricultureo Irrigation - 22% used for industrial processeso Cooling water plantso Newspaper processing- 8% is pumped into cities and homes for drinking, washing, and wateringFreshwater Issues- Quantityo Per capita basis is importanto Strains on Quantity: Population growth Climate change- increased evaporation and instances of droughto Quantity Solution: Dams Stores runoff Can produce hydropower Economic growth- jobs Help with flood control Improves navigationo Dam problems Disturbs natural water flows Disrupt fish spawning Prevents sedimentation- Mississippi River Delta GHG emissions from reservoirs- Methane, CO₂ because they flood out regions to form dams Displaces people Water-borne disease risko Other solutions Recycling- collecting rain in barrels Conservation Desalination- Qualityo Point-source solution- pollution identified as coming from a specific locationo Nonpoint-source solution- broad, more dissipated, not as easy to pinpoint one source ofpollution Car emissions contributing to water pollution Power plants Pesticides Runoff Agriculture Waste waterQuality Issues:- Nutrientso Nitrogen and phosphorus contribute to eutrophicationo Gulf of Mexico Dead Zoneo Combined sewage overflow Under wet conditions, contaminated waste water flows out into the river (Potomac)- Inorganic Pollutantso Metals- bioaccumulation (buildup of material in fatty tissue), biomagnification (as you move up food chain, material accumulates and magnifies as you go up the chain)o Salts- accumulation at toxic levelso Acids and bases- ecosystem damages- Organic Pollutantso DDT cuts back on malaria, but has impacts on the environmento Water → zooplankton → small fish → large fish → fish-eating birds (biomagnifications- 10 million time increase!)- Infectious agentso Direct from water: typhoid, cholera, dysentery, polioo Water-borne vectors: malaria, yellow fevero Less-developed countries: 2.5 billion people lack adequate sanitation; about half of these are without clean drinking watero Cholera in Haiti- Sedimento Good in small amounts, but excess is bado Declines in oxygen level- makes water less clear, so less light gets through to oxygen-producing specieso Obstructs shipping and hydroelectric turbineso Makes drinking water purification toughControlling Water Quality Issueso Land management for NPS (nonpoint-source solution)o Urban runoffo Agricultureo Examples:o Riparian buffers (trees and grass “filters” to catch sediment)o Permeable surfaces Pavement doesn’t absorb water- more runoff, less deep infiltration for ground watero Limiting:o Airborne pollutants- coal power plants emit large amounts of mercuryo Chemical use reaching waterways- DDTs, pesticides, etc.o Modification of