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Transcript of Water Use, Overuse, and Natural Contamination. China India Iran Israel Jordan Mexico Morocco...
Water Use, Overuse, and Natural Contamination
China
India
Iran
Israel
Jordan
Mexico
Morocco
Pakistan
Saudi Arabia
South Korea
Spain
Syria
Tunisia
United States
Yemen
Withdrawals exceed recharge creating deficits in the aquifer
Over-exploitation of renewableand non-renewable aquifers
Water Mining
Lack of contemporary recharge
GROUNDWATER . (Mm3/yr)
COUNTRY Total use % Non-renewable
Saudi Arabia 21,000 84%
Bahrain 258 35%
Egypt 4,850 18%
Jordan 486 35%
Libya 4,280 70%
Yemen 2,200 32%
Saudi Arabia and Libya, use 77% of the estimated total world extraction of non-renewable groundwater for urban supply and irrigated agriculture.
The Middle East
Falls in the water table between 1982 and 2000 range from 3 to 6 feet per year
Within 15 years Quetta will run out of water if the current consumption rate continues
Pakistan
Water table falling by 8.5 feet per year
Iran: Water Refugees
over pumping by an average of 5 billion tons (3.7 Ma-f)of water per year
Equivalent to 1/3 Iran’s annual grain harvest
Mashad
Villages Abandoned
71 percent drop in wheat harvest from a high of 4.1 million tons in 1992 to 1.2 million tons in 2005,
Saudi farmers are now pumping water from wellsthat are 4,000 feet deep
Paleowater35,000 years old
Qa-Disi Aquifer
water extraction exceeds the annual recharge by a factor of five,
Yemen
pumped dry by 2010
Options:
relocate the capitalpipelines
Water table dropping 6 meters (18 ft) per year
Other Large Deficits
IndiaChinaPakistan
½ the world’stotal use of groundwaterfor agriculture
Pumping: 325 million acre feet
Recharge: 205 million acre feet
Deficit: 120 million acre feet
1 acre-foot = 325,851 gallons
Area = 1 acre1 foot
Deep wells must reach more than half a mile to tap fresh water
Level of the deep aquifer is dropping nearly 3 meters (10 feet) per year
Deficit feeds 100 million people
Shallow , unconfinedaquifer depleted
water table falling by 20 feet per year
Deficit feeds 200 million
21 million wells
Failure of 246 surface irrigation projects
$600 electric pumps (1% of GDP)
Deficit of 80 million acre-feet
India
95 %
5 acres of land
Pumps 3200 gallons/hr
Irrigates alfalfa for 64 hours
24 times per year
Yield: 6.5 gallons milk/day
4.9 million gallons => 2400 gallons milk (2000 gallons water/ gallon milk)
4.9 million gallons water/yr
United States
United States
1/3 of irrigation water comes from groundwater
The 3 largest aquifers are in arid/semi-arid regions
Ogallala Aquifer MidwestCentral Valley Aquifer CaliforniaSouthwest Aquifer System Arizona, Utah, Nevada
Central Valley Aquifer (California)
Pumping 15% more water than is replaced
Southwest Aquifer (Utah, Nevada, Arizona)
Pumping 50% more water than is replaced
Deficit of 30 million acre-feet
Water storage capacity has declined by 50%
High Plains Aquifer (Ogallala)¼ gone in areas of Texas, Oklahoma, Kansas
Water table declines up to 100 feet in some areas
Phoenix Arizona Growing 2 acres/hr
Among the highest water users
tripled in population over the last 40 years
Tucson
Canal 335 miles long
44 billion gallons/yr
7% lost to evaporation
Central Arizona Project
Use, Overuse, Quality
USTsLandfillsSeptic systemsUrban RunoffAgricultureIndustryRainfall
ContaminantSources
Natural Groundwater Contaminants
Tapping water as deep as 1,000 meters
water table falling by 20 feet per year
21 million wells
India
Deeper Wells and Fluoride
Naturally occurring element in Granitewhich dissolves into the groundwater
Water near the surface is generally unaffected
Lowering water tables = deeper wells
Deep groundwater contains high fluoride levels
fluoride in water can be a cumulative poison
Intentional Fluoridation of Water in the U.S.
Fluoridation became an official policy of the U.S. Public Health Service in 1951.
By 1960 water fluoridation had become widely used in the U.S. reaching about 50 million people.
By 2006, 69.2% of the U.S. population on public water systems were receiving fluoridated water.
How does it work?
Tooth enamel is made of a mineral called hydroxyapatite
Ca5(PO4)3OH
Hydroxyapatite is subject to dissolution by acids (H+)
Fluoridation changes the chemical composition ofhydroxyapatite to a crystal less subject to acid dissolution
Bacteria in the mouth create acids (H+)
Ca5(PO4)3
Sodium fluorosilicate (Na2SiF6)
Sodium fluoride (NaF)
NaF Na+ + F-
OH
Ingestion of fluoridated water increases the F- concentration in saliva
F- replaces OH in hydroxyapatite making fluoroapatite
F-
Fluoroapatite is less soluble in acid than hydroxyapatite
Fluoride concentrationsIn U.S. tap water
0.6 – 1.1 mg/L
Lower values in warm climates
1.6 to 6.6 mg/day
Colorado Brown Stain
Dental Fluorosis
Intake:
Permissible fluoride limit in India is 1.2 mg/L
Fluoride levels between 5-25 mg/L have been found
Fluoride levels > 1.5 mg/L
9 mg/day to 12 mg/day
Fluorosis has risen from 1 million to 25 million and now to 60 million people in India.
Skeletal Fluorosis
Intake
Fluoride levels > 10 mg/L
Groundwater and Arsenic
Arsenic is Naturally Occurring
occurs primarily in association with sulfur-containing minerals
mean values of arsenic content in soils, the earth’s crust, and sediments are between 1.5, and 7.7 mg/kg
Mobilization of arsenic in the environment arises from anthropogenic activities related to mining and ore processing,
metallurgy, agriculture, wood preservation, and industry.
Natural waters, in general, contain low levels of total arsenic
Inorganic Forms of Arsenic
AsO4-3AsO3
-3
Arsenite Arsenate
Low Oxygen High Oxygen
Arsenite is more toxic than arsenate, interfering withenzyme activities which catalyze metabolic reactions
Arsenite compounds are also more mobile in the environmentdue to higher solubility compared to arsenate compounds
Both arsenate and arsenite are chronic accumulative toxins
“The World’s Largest Mass Poisoning”
Bangladesh and W. India
ranked among the world's 10 poorest countries
Accumulation ofthick mudsin the floodplainsand deltas
Floodplain and Delta of theGanges and Brahmaputra Rivers.
Floodplain: area paralleling a river that is periodically inundated
Deltas are formed from the deposition of sediment carried by the river as the flow leaves the mouth of the river
Himalayas
Ganges-Brahmaputra Delta
Prior to 1970s
One of the highest infant mortality rates in the worldPrincipally due to waterborne disease.
Ineffective water and sewage systemsPeriodic monsoons and floods
cholera, dysentery
water-borne pathogens
Deaths Due to Surface water contamination: 250,000/yr
Deaths Due to Surface water contamination: 250,000/yr
The Solution: Tap groundwater resources
• easy• inexpensive
First 1 million were sunk with aid fromWorld Governments
UNICEFWorld Bank
12 million hand-operated tube wellsdeliver water to over 80% of the rural village population
Infant mortality and diarrheal illness reduced by 50%
Wells in Floodplain and Delta Sediments
Water Bearing Muds
Natural erosion ofarsenic to water-bearing units.
Well depths between 20m and 100 m
Majority of wells > 50 ppb arsenic Some wells contain 500 - 1000 ppb
WHO/U.S limit: 10 ppbBangladesh limit: 50 ppb
Exposure Estimates
Above 50 ppb: 35 million
Above 10 ppb: 57 million
Early Symptoms:
Skin lesions and thickeningStrong skin pigmentation
2003 Studies
83 million people
Bihar: 40% wells contaminated
Red River Delta
11 million people
First wells sunk7 years ago
End Lecture 17
Next: Florida’s Aquifers
Sea Levels
Temporary reestablishment of carbonate deposition
Vulnerability
One gallon of gasoline cancontaminate 1 million gallonsof drinking water
1 ppm
MetalsNutrientsPesticidesPetroleum Solvents