Critical Resource Required for Life Air Minerals Energy
Water H 2 O Molecule Covalent Bonds Hydrogen Bonds
Physical Properties Unusually high boiling point Expands when frozen High specific heat
Biological Properties Great solvent Transport media Support media
Critical Resource Quantity: for a growing population All Earth’s water in a gallon jar Available fresh water = one tablespoon Other fresh water = two tablespoons Quality: given use and misuse
Water for People Lakes (Florence…Clear Lake) Rivers (Grants Pass…Rogue River) Groundwater (Rural Oregon…Wells)
Large Urban Areas San Francisco Yosemite…Hetch Hechy Reservoir Portland… Bullrun Watershed Wells along the Willamette Medford Little Butte Creek Rogue River
Agriculture 40% US water to agriculture 5% of US farmland is irrigated These produce 20% of farm products 1 Gallon milk = 4 Gallons water 1 Tomato = 8 Gallons water
Electric Power More water used here than any other use 4,000 Gallons = 1 kilowatt 10 - 100 W light for 1 hour 90% = Thermoelectric = 131 X 10 9 Gal/day 10% = Hydroelectric
Industry 36 X 10 9 Gal/day Paper, petroleum, chemicals, metals Commercial (military, college, office, restaurant)
Domestic Use Toilets, showers, lawns, washing clothes Toilet – 3.5 to 7 Gal/flush (low-flow = 1.6 gal)
Environmental Use Stream flow minima Wildlife habitat Recreation
Conservation One penny = 160 eight-ounce glasses Why conserve?
Source(s) of Water – Only one source….Earth….Ocean – Fresh water….Sun – Land – watersheds – streams – Rivers – lakes – reservoirs – ocean
A particular area of concern for many people is groundwater contamination. Groundwater is usually defined as water that lies below the surface of the land. For practical purposes, though, groundwater is usually thought of as water underground that can be removed by wells. Those sources of ground water are referred to as aquifers. When an aquifer becomes contaminated, that contamination can affect a wide area – and take years to clean up. Some common sources of groundwater contamination include improper disposal of wastes, faulty septic tanks, landfills, pesticides and fertilizers.
Types of Groundwater Contamination Groundwater pollution caused by human activities usually falls into one of two categories: point-source pollution and nonpoint-source pollution. Point-source pollution refers to contamination originating from a single tank, disposal site, or facility. Industrial waste disposal sites, accidental spills, leaking gasoline storage tanks, and dumps or landfills are examples of point sources.
Chemicals used in agriculture, such as fertilizers, pesticides, and herbicides are examples of nonpoint- source pollution because they are spread out across wide areas. Similarly, runoff from urban areas is a nonpoint source of pollution.
Natural Substances Some groundwater pollution occurs naturally. The toxic metal arsenic, for instance, is commonly found in the sediments or rock of the western United States, and can be present in groundwater at concentrations that exceed safe levels for drinking water. Radon gas is a radioactive product of the decay of naturally occurring uranium in the Earth's crust. Groundwater entering a house through a home water- supply system might release radon indoors where it could be breathed.
Petroleum-based Fuels One of the best known classes of groundwater contaminants includes petroleum-based fuels such as gasoline and diesel. Nationally, the U.S. Environmental Protection Agency (EPA) has recorded that there have been over 400,000 confirmed releases of petroleum- based fuels from leaking underground storage tanks.
Gasoline consists of a mixture of various hydrocarbons (chemicals made up of carbon and hydrogen atoms) that evaporate easily, dissolve to some extent in water, and often are toxic. Benzene, a common component of gasoline, is considered to cause cancer in humans, whereas other gasoline components, such as toluene, ethylbenzene, and xylene, are not believed to cause cancer in humans but may be toxic in other ways.
Chlorinated Solvents Another common class of groundwater contaminants includes chemicals known as chlorinated solvents. One example of a chlorinated solvent is dry-cleaning fluid, also known as perchloroethylene. These chemicals are similar to petroleum hydrocarbons in that they are made up of carbon and hydrogen atoms, but the molecules also have chlorine atoms in their structure.
The International Agency for Research on Cancer has classified tetrachloroethene as a Group 2A carcinogen, which means that it is probably carcinogenic to humans. Like many chlorinated hydrocarbons, tetrachloroethene is a central nervous system depressant and can enter the body through respiratory or dermal exposure. Tetrachloroethene dissolve fats from the skin, potentially resulting in skin irritation.
Tetrachloroethene is a common soil contaminant. Because of the mobility of PCE in groundwater, its toxicity at low levels, and its density (which causes it to sink below the water table), cleanup activities are more difficult than for oil spills. Recent research has focused on the in place remediation of soil and ground water pollution by tetrachloroethylene. Instead of excavation or extraction for above-ground treatment or disposal, tetrachloroethylene contamination has been successfully remediated by chemical treatment or bioremediation. Bioremediation has been successful under anaerobic conditions by reductive dechlorination by Dehalococcoides sp. and under aerobic conditions by cometabolism by Pseudomonas sp.
MTBE: GASOLINE ADDITIVE Methyl tert -butyl ether (MTBE) is used almost exclusively as a gasoline additive to help reduce harmful tailpipe emissions from motor vehicles. MTBE has been credited with improving air quality by significantly reducing carbon monoxide and ozone levels in areas where the additive has been used. But…
There is widespread concern about MTBE in drinking- water sources because of potential human-health effects and its offensive taste and odor. The U.S. Environmental Protection Agency has tentatively classified MTBE as a possible human carcinogen, but has not yet established a drinking- water regulation. The agency, however, has issued a drinking-water advisory of 20 to 40 micrograms per liter (20 to 40 parts per billion) on the basis of taste and odor thresholds.
1 Maximum Contaminant Level Goal (MCLG) - The maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health effect of persons would occur, and which allows for an adequate margin of safety. MCLGs are non- enforceable public health goals. 2 Maximum Contaminant Level (MCL) - The maximum permissible level of a contaminant in water which is delivered to any user of a public water system. MCLs are enforceable standards. The margins of safety in MCLGs ensure that exceeding the MCL slightly does not pose significant risk to public health.
Contaminates A milligram per liter of water is equivalent to 1 ppm (part-per-million) because a liter of water weighs 1000 grams and a milligram is 1 one thousandth of a gram. The various forms of nitrogen and phosphorus most available to plants (nitrate-N, ammonium-N and phosphate-P) are typically present at concentrations or levels of only 0.001 to 0.500 mg/L. These are typically expressed as micrograms-per-liter or ug/L. A microgram /L is 1 one thousandth of a milligram/L. It is also equivalent to 1 ppb (part-per-billion).
Toxic pollutants such as heavy metals like cadmium and mercury usually exist at sub - ppb levels and can be considered to be a problem at ppb levels. Some organic contaminants, a diverse group of chemicals that includes pesticides, PCBs and dioxins, may be measured at sub- ppb levels and may be expressed as ng/L (nanograms-per-liter = parts-per- trillion) or even 1 pg/L (picograms- per-liter = parts-per-quadrillion).
These are all very dilute concentrations and below are listed some comparisons to provide some intuitive feel for how low these levels are. By the way, seawater has a salt content of about 32 g/L (32 parts-per-thousand which is the same as 3.2 % since 1 percent = 1 part-per-hundred). This is also equivalent to 32,000 ppm (part-per-million).
Concentrations One-Part-Per-Million one automobile in bumper-to-bumper traffic from Cleveland to San Francisco one inch in 16 miles one minute in two years one ounce in 32 tons one cent in $10,000
One-Part-Per-Billion one 4-inch hamburger in a chain of hamburgers circling the earth at the equator 2.5 times one silver dollar in a roll of silver dollars stretching from Detroit to Salt Lake City one kernel of corn in a 45-foot high, 16-foot diameter silo one sheet in a roll of toilet paper stretching from New York to London one second of time in 32 years
One-Part-Per-Trillion one square foot of floor tile on a kitchen floor the size of Indiana one drop of detergent in enough dishwater to fill a string of railroad tank cars ten miles long one square inch in 250 square miles one mile on a 2-month journey at the speed of light
One Part Per Quadrillion one postage stamp on a letter the size of California and Oregon one human hair out of all the hair on all the heads of all the people in the world one mile on a journey of 170 light years
See the handout for values of many contaminates…