ENVI-1020 Chapter 11 Water Resources & Pollution
ENVI-1020 Chapter 11 Water Resources & Pollution ENVI 1020 - 001
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This 7 page Class Notes was uploaded by Cory Garfunkel on Sunday April 3, 2016. The Class Notes belongs to ENVI 1020 - 001 at Auburn University taught by Robert F. Holm in Spring 2016. Since its upload, it has received 32 views. For similar materials see Fundamentals of Environmental Science in Science at Auburn University.
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Date Created: 04/03/16
Chapter 11 Water Resources & Pollution Water Resources Water Resources-Sources of water useful or potentially useful to humans (and aquatic organisms) o Human Uses—agriculture, industry, household, recreation, environmental activities Hydrologic Cycle—Precipitation, evaporation/transpiration, condensation, precipitation… o Runoff and Ground Infiltration are also key parts in the “loss” and “gain” of usable water respectively Water Distribution o Ocean—97.5% o Freshwater—2.5% Glaciers/Ice-Caps—68.7% Ground 30.1% Permafrost—0.8% Surface & Atmosphere—0.4% Lakes—67.5% Soil Moisture—12% Atmosphere—9.5% Wetlands—8.5% Rivers—1.5% Vegetation—1% World's supply of clean, fresh water is steadily decreasing; Demand exceeds supply in much of the world. As world pop. continues to rise, water demand does too. Global awareness of preserving water has started happening only recently: during the 1900’s, more than half of the world’s wetlands were lost. o Biodiversity-rich freshwater ecosystems are currently declining faster than marine or land ecosystems. Hydrologic Terms o Surface water–precipitation that remains on the surface of land and does not seep into soil Ex. Vineyard in France o Runoff (overland flow)–movement of freshwater from precipitation & snowmelt to rivers, lakes, wetlands and ultimately the ocean o Watershed–Area of land drained by a single river or stream Ex. Red River Mine runoff into Watershed o Groundwater–Supply of freshwater stored in underground aquifers o Water table—Boundary between water-saturated ground and unsaturated (Vadose) ground o Aquifer–Underground geological formation able to store and yield water Use of Freshwater in U.S. o Irrigation—82% o Domestic –7% o Livestock & Industry—3% EACH o Thermoelectric Power—3% o Commercial & Mining—1% EACH 800 gallons/lb. beef 100,000 gal/car produced 1,000 gal/lb. aluminum produced (RECYCLE!) Quantity Used o Worldwide water use has been increasing 2x population growth rate over past century Agriculture claims about 70% of total water withdrawal Many developing countries, agricultural water use is extremely inefficient & highly consumptive Industry accounts for about 25% of all water use Cooling water for power plants is single largest industrial use Water Use o Average North American uses 400 Liters/day; European uses 200 L o Average person in developing world uses 10 L/day for drinking, washing, and cooking o On current trends, over the next 20 years, humans will use 40% more water than now o Agriculture accounts for over 80% of world’s water consumption Education and Economy o 443 million school days are lost each year due to water-related diseases o 11% more girls attend school when sanitation is available o 40 billion working hours are spent carrying water per year in Africa o Rural African households (usually women) spend ~26% of their time fetching water Freshwater Shortages o Estimated 1.1 billion people lack access to adequate supply of drinking water o 2.4 billion lack acceptable sanitation o In a country where consumption exceeds more than 20% of available water, renewable supply is considered vulnerable to water stress o Global water supplies are abundant but is unevenly distributed Depleting groundwater o Groundwater—source of nearly 40% of freshwater in the U.S. o On a local level, withdrawing water faster than it can be replenished leads to a cone of depression in the water table o On a broader scale, heavy pumping can deplete an aquifer Ogallala aquifer o Like mining a non-renewable resource o Withdrawing large amounts of groundwater in a small area causes porous formations to collapsesubsidence Sinkholes form when an underground channel or cavern collapses o Saltwater intrusion can occur along coastlines where overuse of freshwater reservoirs draws water table low enough to allow saltwater to intrude Means for Supplying more Water o Dams, Reservoirs, & Canals—Trap excess water in areas of excess & transfer it to areas of deficit Environmental Costs—Upsets natural balance of water systems Ecosystem Losses—Loss of Wildlife habitat depending on reservoir size & water quality Problems Displacement of people o 3 gorges dams in China will/has force(d) relocation of over 1 million people Evaporation, leakage, siltation o Evaporative losses from Lake Mead and Lake Powell (2 of 6 major ones) on Colorado River is about 1 km³/year (264 billion gallons) o Dams slow water flow, allowing silt (nutrients) to drop out Loss of free-flowing rivers o Water Transfer o Groundwater o More Efficient Use Increased future wastewater use and desalination are likely mechanisms for increasing water supply in semi-arid and arid regions; desalination has its own environmental impacts Desalination—process that removes dissolved minerals (including but not limited to salt) from seawater, brackish water, or treated wastewater. o Techniques—reverse osmosis (RO), distillation, electrodialysis, vacuum freezing By 2007, Tampa bay, FL had a 25 million gallon/day desalination project Watershed Management Watershed—all the land drained by a stream or river Retaining vegetation and ground cover helps retard rainwater and lessens downstream flooding Retaining crop residue on fields reduces flooding Minimizing plowing and forest cutting on steep slopes protects watersheds Domestic Conservation Estimates suggest many societies could cut water usage in half without great sacrifice or serious change in lifestyle o Largest domestic use is toilet flushing Small volume of waste in large volume of water Significant amounts of water can be reclaimed and recycled Purified sewage effluent If it’s yellow, let it mellow. If it’s brown flush it down. You save 1.6-7.0 gallons!!! every flush. Install water saving flushers or waterless urinals Water Pollution **Any physical, biological, or chemical change in water quality that adversely affects living organisms can be considered pollution Flying Toilets o Kibera slum of Nairobi, Kenya has an average of one toilet (pit latrine) for over 500 people. o Residents use polyethylene bags to relieve themselves and then dispose of them in the streets near creeks that may flow through town Amref has built safe water points throughout the slum Sources of Pollution o Point sources—Discharge pollution from specific locations (i.e. factories, sewage treatment plants, mines, oil wells, oil tankers) o Non-point sources –Scattered or diffuse, having no specific location of discharge (i.e. acid deposition, runoff, seepage into groundwater) o Agriculture is largest source of water pollution (non-point) in the U.S. (64% of pollutants into streams & 57% of pollutants entering lakes) Can create offshore sediment plumes (i.e. Dominican Republic, Lake Tahoe) Water pollutants o Disease-Causing Agents o Oxygen Demanding Wastes o Water-Soluble Inorganic Nutrients o Inorganic Pollutants o Organic Chemicals o Sediment o Thermal and/or biological pollution Infectious Agents o Main source of waterborne pathogens is untreated and improperly treated human waste Animal wastes from feedlots and fields can also be a source of pathogens Examples Amoebic Dysentery Dracunculiasis (Guinea Worm) Dysentery Giardia Hepatitis A Trachoma—6 million people blind (Chlamydia trachomatis) Traveler’s diarrhea Typhoid fever Schistosomiasis—200 million people infected (prevalent in 52 countries) Ascaris Cholera (Cholerabacterium, Vibrio)—worldwide problem (i.e. Oregon Trail) Most frequent diseases related to poor water quality: Diarrhea—Approx. 4 billion cases/year o 2.2 million deaths, mostly in young children Intestinal Worms—Infect 10% of population of developing world Oxygen-Demanding Organic Wastes o Organic matter accumulates in an aquatic environment and oxygen-requiring bacteria deplete the oxygen in the water in the process of degrading this matter o Biological Oxygen Demand (BOD)—measure of concentration of organic matter in water In spill areas, there’s clean zones, decomposition zone, septic zone, & recovery zone Organic Chemicals o 1000’s of natural & synthetic organic chemicals are used to make pesticides, plastics, pharmaceuticals, pigments, etc. o 2 most important sources of toxic organic chemicals in water: Improper disposal of industrial and household wastes Runoff of pesticides from high-use areas like fields, roadsides, golf courses o Examples of effects on wildlife Mammals: reproductive and immune effects in Baltic seals (PCBs, DDE) Birds: eggshell thinning, altered gonadal development, (DDT) and embryonic abnormalities (PCB) Cormorant with cross bill syndrome Reptiles: decline in alligators in Florida, USA (organochlorine spill) Fish: reproductive alterations (from paper mills and sewage) Invertebrates: masculinization & decreased pop. (TBT, a boat antifouling agent) Inorganic Nutrients and Eutrophication o Natural eutrophication (enrichment of ecosystem with chemical nutrients, typically compounds containing nitrogen, phosphorus, or both) and lake aging takes centuries o Cultural or Anthropogenic eutrophication and lake aging takes decades o Lake Erie aged from 1950-1975 as much as it had in last 15,000 years; vastly improved since Heavy Metals o Mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), and lead (Pb) have no known vital or beneficial effect on organisms; their accumulation over time in bodies of mammals can cause serious illness. Some of them such as Hg and PCB’s (polychlorinated biphenyls) biomagnify as they move up the food chain, resulting in tumors & death for predatory animals, such as lake trout, herring gulls, & humans Minamata Disease o First discovered in Minamata, Japan in 1956; caused by release of methylmercury in industrial wastewater from a chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which when eaten by the local populace resulted in mercury poisoning. Human consumption of fishes, shellfish and crustaceans high on the food chain resulted in mercury poisoning of as many as 12,000 victims. While cat, dog, pig, and human deaths continued over more than 30 years, the government and company did little to prevent the pollution. Sediment o Human activities have accelerated erosion rates in many areas Cropland erosion -25 billion metric tons/yr Forestry, road, building, construction – 50 billion metric tons/yr o Sediment can either be beneficial (nourish floodplains) or harmful (smother aquatic life) o Low sediment bedload environments have hiding places for small fish; bacteria, protozoan, & insect larva attached to rocks; good light penetrationphotosynthesisgood food chains o High Sediment Bedload environments totally opposite. Thermal Pollution o Nuclear Reactors use rivers/lakes as heat sinks to cool reactor watertemperature rises in river/lakedramatic changes in living conditionsdie-offs and changes in food chain Exotic Species of Animals & Plants o Deliberately or Accidently imported—i.e. Goldfish, zebra mussels (Monroe, MI) Managing Surface Water Pollution in USA o Clean Water Act (1972, 1977), Water Quality Act (1983) Ideas: to make U.S. surface waters safe for fishing & swimming by 1983 & to restore chemical, physical, & biological “integrity” of waters Progress made, but goals not met CWA established National Pollution Discharge System—requires permit to dump wastes in surface waters In 1999, EPA reported 91.4% of all monitored river miles & 87.5% of all accessed lake acres are suitable for their designated uses o Most progress due to municipal sewage treatment facilities o Remaining Problems Greatest impediments to achieving national goals in water quality are sediment, nutrients, and pathogens, especially from non-point discharges About 3/4 of US water pollution from soil erosion, air pollution, fallout, & agricultural & urban runoff Single cow produces 30 kg manure/day Some feedlots have 100,000 animals! Problems & Progress in Other Countries o Sewage treatment in wealthier countries of Europe generally equal or surpass the US o Russia: only about 1/2 of tap water supply is safe to drink o In urban areas of South America, Africa, & Asia, 95% of all sewage is discharged untreated into rivers o 2/3 of India’s surface waters are contaminated sufficiently to be considered dangerous to human health Plastic Ocean—Great Pacific Garbage Patch and other associated o Estimated 6 million metric tons of plastic bottles, packaging material, & other litter tossed from ships into ocean annually o Few coastlines in the world remain uncontaminated by oil or oil products Statistics o Only 63% of world pop. has access to improved sanitation (2.5 billion people) o Nearly 1 Billion people lack access to safe water o Major Sources of U.S. Stream Pollution Non-point—65% Background—6% Municipal—17% Industrial—9% Other—3% } Point Sources