Water Flashcards
1
Q
Nile
A
-shared by 10 countries
-most water used by Egypt, Sudan,
and Ethiopia
-Egypt gets more than 97% of
water from Nile and last in line
-must import 40% of grain to feed
growing population
-Ethiopia and Sudan plan to divert
more water from the Nile ->
decreased water availability in
Egypt
- Egypt’s options:
> go to war w/ Sudan & Ethiopia
> cut population growth
> increase irrigation efficiency
> work out water sharing agreements
2
Q
Tigris-Euphrates
A
-shared by turkey, Syria, and Iraq
- turkey:
> at headwaters -> controls flow
downstream
> building 24 dams to generate
electricity for irrigation
> will reduce flow by 35% or more
- Syria plans to build dams -> less
water for Iraq -> may lead to war
between Syria and Iraq
3
Q
Jordan
A
- most water - short region
- share by Jordan, Syria, and Israel
- population in area expected to
double by 2050 - 1994: Israel and turkey signed a
treaty which turkey will supply
Israel with water in exchange for
weapons - Syria plans to build dams -> Israel
threatened to destroy dams
4
Q
Waters Importance
A
- oceans help regulate climate
- oceans dilute and degrade wastes
- oceans provide habits for many
species - organisms are made up mostly of
water - water used in:
> agriculture
> manufacturing
> transportation
5
Q
Surface water
A
- surface runoff - rivers, lakes, reservoirs - watershed (drainage) basin - reliable runoff - 1/3 of total (2/3 lost by seasonal floods)
6
Q
Groundwater
A
- zone of saturation
- water table
- aquifers - porous, water -
saturated layer of groundwater
that can be economically used - natural recharge - replenished
from the side by nearby streams
7
Q
Aquifers
A
- if rate of withdrawal > rate of
renewal…
> salt-water intrusion may occur
in coastal areas
> depletion of aquifer may result
in decreased flow of rivers and
streams fed by aquifer - fossil aquifer
> gets very little recharge on a
human scale
> considered a non-renewable
resource
> “water mining” - withdrawal of
large amounts is water from
ancient water deposits
8
Q
Case study: freshwater resource in the USA
A
- Western USA - water poor
> too little precipitation
> groundwater
> large use: irrigation (85%)
> water problems
-> shortage of runoff
-> prolonged drought
-> decreased water table
(sinkholes)
- Eastern USA - water rich
- ample precipitation
- surface water
- largest use:
-> energy productivity
-> cooling
-> manufacturing
- water problems
-> flooding
-> occasional shortage
-> pollution
( ex. 3 million Long Island NY
residents rely on and
increasingly contaminated
aquifer)
9
Q
World Statistics
A
- 2002 UN report: > 500 million people live in water stressed/ water scarce areas -> projected to increase to 2.4 - 3.4 billion people by 2025 - china: water supply can only support 50% of it's current population - water shortages will cause: > decreased food production > decreased economic growth and development - 1 out of 6 people - no regular access to clean water and live in hydrological poverty > cannot afford safe, clean water > do not have municipal water supply and most use unsafe water or buy water
10
Q
Human activities worsen flooding
A
- urbanization > paving and building -> increase runoff - draining wetlands (that absorb floodwaters) - removal of water - absorbing vegetation on hill slopes - increased population living on floodplains
11
Q
Channelization: reducing flooding risks
A
- the straightening, widening, and
deepening of a stream
> advantages:
-> decreased upstream flooding
> disadvantages:
-> can increase bank erosion
(due to increased velocity)
-> can increase downstream
flooding
-> can increase sedimentation
downstream
-> \$\$$
12
Q
Levees
A
- increase streams capacity to hold
water
> advantages:
-> decreased flooding
> disadvantages:
-> false sense if security ->
people build too close
-> if water breeches levee ->
cannot recede -> areas stay
underwater longer
13
Q
Identify and manage flood-prone areas
A
- zoning laws:
> examine historical records and
create flood frequency/flood
hazard maps
> ban buildings in high risk zones
> elevated buildings
> construct a flood way that
allows water to flow through a
community with minimal
damage
14
Q
Stream Pollution
A
- natural recovery processes
> can recover rapidly from
degradable, oxygen- demanding
wastes or excess heat by a
combination of dilution and
bacterial decay
15
Q
Resolving water distribution problems requires:
A
- regional cooperation
- decreased population growth
- increased efficiency in water use
- higher water prices
- increased grain imports
- improvements in irrigation
16
Q
Water’s Unique Properties
A
- liquid water exists over a wide
temperature range
- water filters out UV -> protects
aquatic organisms
- water's high specific heat ->
change temperature slowly
> helps protect organisms from
abrupt temperature changes
> moderates climate
> excellent coolant
- superior solvent - can dissolve
many compounds
> carry dissolved nutrients into
tissues in organisms
> flush wastes out if tissues
> all-purpose cleanser
> note: this property of water
causes it to become easily
polluted
- E-X-P-A-N-D-S as it freezes -> ice
floats and life can continue in
ponds and lakes during cold
winter months
17
Q
Flowing Artesian Wells
A
- ordinary well:
> needs energy to extract
> unconfined aquifer - more likely
to be polluted
- wells A & B
> flowing artesian wells: flow
under their own natural pressure
> confined aquifer - less likely to
be polluted because of small
recharge area
18
Q
World Average Water Use
A
70% - water withdrawn is used for
agricultural reasons (typically
irrigation)
20% - water withdrawn is for
industrial use
10% - water withdrawn is used for
residential use
19
Q
Case Study: Freshwater Resources in USA
A
- USA has enough water for
everyone, but much is in the
wrong place at the wrong time
20
Q
Water Hot Spots in Western States
A
- water hot spots in 17 USA western states that, by 2050, could ave intense conflicts over scarce water needed for urban growth, recreation, and wild life
21
Q
Freshwater Shortages
A
- dry climate/aridity
- drought
> a period of 21 days (or longer) in
which precipitation is at least
70% lower than normal - desiccation
> drying of exposed soil due to
deforestation, overgrazing - water stress
> low per capita availability (due
to increased population relying
on fixed supply)
22
Q
Hydrological Poverty
A
- developed countries have the
ability to bring water into needed
areas
- developing countries, the people
are forced to live where the water
is
> water quality may decline from
animals
> improper disposal of waste
> water for bathing may also be
water for drinking
23
Q
Solutions: Increasing Freshwater Supplies
A
- dams
- watershed transfer
- tapping groundwater
- desalination
- water conservation/curbing waste
24
Q
Trade-offs of Large Dams and Reserviors
A
- provides irrigation water above and below
dam - provides water for drinking
- reservoir useful for recreation and fishing
- can produce cheap electricity (hydro-
power) - reduces downstream flooding
- flooded land destroys forests or cropland
and displaces people - $$$ to build
- large losses of water through evaporation
- deprives downstream cropland and
estuaries of nutrient rich soil - risk of failure and devastating downstream
flooding - disrupts migration and spawning of some fish
25
Q
Case Study: China’s Three Gorges Dam
A
- “Great Wall across the Yangtze”
- will be the world’s largest hydroelectric
dam and reservoir
> dam - 1.2 miles long
> reservoir - 370 miles long - will be completed in 2013
- cost $25 billion
- will displace 1.9 million people
- will generate the electrical equivalent of 20
coal pr nuclear power plants - will decrease downstream flooding (which
has killed 500,000 people during past 100
years)
26
Q
TRADE OFFS
China’s Three Gorges Dam
A
-advantages
> will generate about 10% of china's
electricity
> reduces dependence on coal
> reduces air pollution
> reduces CO2 emissions
> reduces chances of downstream flooding
for 16 million people
> reduces river sitting below dam by
eroded soil
> increases irrigation water for cropland
below dam
- disadvantages
> floods large areas of cropland and
forests
> displaces 1.9 million people
> increases water pollution because of
reduced water flow
> reduces deposits of nutrient-rich
sediments below dam
> increases saltwater introduced into
drinking water near mouth of river
because of decreased water flow
> disrupts spawning and migration of
some fish below dam
> high cost
27
Q
Case Study: Aral Sea Disaster
A
- large-scale water transfers in dry central
Asia (Uzbekistan and Kazakhstan - former
Soviet Union) - since 1960, water was diverted from Aral
sea and 2 feeder rivers for irrigation canal -
8– miles long - world’s longest irrigation canal - 800 miles
- salinity - increase 3x
-surface area - decreased 54% - volume - decreased by 15%
- 14.000 square miles of human-made salt
desert - flash extinctions and loss of fishing
industry
> 60,000 people unemployed - wetland destruction and wildlife - loss of
50% of all bird and animal species - “salt rain”
> wind blown salt -> kills crops
> salt settling on glaciers in the
Himalayas -> accelerating melting - climate changes
> decreased moderating effect of sea ->
hotter summers, colder winters
> less rain
> shorter growing season - increased use of pesticides and fertilizers
by farmers -> groundwater contamination
-> increased infant mortality and cancers - 20-50% decreased crop yeild
28
Q
TRADE OFFS
Withdrawing groundwater
A
- advantages
> useful for drinking and irrigation
> available year-round
> exists almost everywhere
> renewable if not over-pumped or
contaminated
> no evaporation losses
> cheaper to extract than most surface
waters
- disadvantages
> aquifer depletion from over-pumping
> sinking of land (subsidence) for
over-pumping
> aquifers polluted for decades or
centuries
> saltwater intrusion into drinking water
supplies near coastal areas
> reduced water flows into surface waters
> increased cost and contamination from
deeper wells
29
Q
Case Study: Ogallala Aquifer
A
- world’s largest known aquifer
- mid-western U.S. - 8 states (South
Dakota, Nebraska, Kansas, Colorado,
Wyoming Oklahoma, New Mexico, Texas) - fossil aquifer - filled during last ice age
- being pumped 8-10x faster than natural
recharge rate - transformed prairie land (with little rain) ->
productive farmland that produces 20% of
agricultural output ($32 billion/year) - depletion is encouraged by government
subsidies to farmers to grow “thirsty”
crops, and not to improve efficiency of
irrigation
NOTE: of all the water from the Ogallala aquifer was on the surface, it would cover all 50 stats with 1.5 feet of water
30
Q
Case Study: James Bay Watershed Transfer
A
- involved creating 600 dams to alter, and
even reverse, the flow of 19 giant rivers - would flood areas utilized by Cree and
Inuit tribes - phase 2 was postponed due to opposition
and the fact that phase 1 created more
electricity than could be sold
31
Q
Benefits of Reducing Water Waste
A
- reducing waste to 15% will allow us to meet most of the world's water demands for the foreseeable future - decrease burden on waste water plants - decreased need for dams and water transfer projects (will disrupt fewer habitats and displace less people) - slow groundwater depletion - save $ - save energy
32
Q
Reducing Irrigation Water Waste
Solutions
A
- line canals bringing water to irrigation
ditches - irrigate at night to reduce evaporation
- monitor soil moisture to add water only
when necessary - grow several crops on each plot of land
(poly-culture) - encourage organic farming
- avoid growing water-thirsty crops in dry
places - irrigate with treated urban waste water
- import water-intensive crops and meat
33
Q
Reducing Water Waste
Solutions
A
- redesign manufacturing processes to use less water - recycle water in industry - landscape yards with plants that require little water - use drip irrigation - fix water leaks - use water meters - raise water prices - use water-less composting toilets - require water conservation in water-short cities - use water-saving toilets, shower-heads, and front-loading clothes washers - collect and reuse household water to irrigate lawns and non-edible plants - purify and reuse water for houses, apartments, and office buildings
34
Q
WHAT CAN YOU DO?
Water Use and Waste
A
- use water-saving toilets and faucet
aerators - shower instead of taking baths, and take
short showers - repair water leaks
- turn off sink faucets while brushing teeth,
shaving, or washing - wash only full loads of clothes or use the
lowest possible water- level setting for
smaller loads - use recycled (gray) water for watering
lawns and household plants and for
washing cars - wash a car from a bucket of soapy water,
and use the hose for rinsing only - if you use a commercial car wash, try to
find one that recycles water - replace your lawn with native plants that
need little if any watering - water lawns and yards in the early
morning or evening - use drip irrigation and mulch for gardens
and flowerbeds
35
Q
Benefits of Flooplains
A
- fertile soil -> productive farmland
- nearby rivers for transportation and
recreation - flatland’s for urbanization and farming
- recharge groundwater
- ample water for irrigation
- highly productive wetlands
36
Q
Dangers of Floodplains and Floods
A
- deadly and destructive
- failing dams and water diversion
- Hurricane Katrina and the Gulf Coast
> removal of coastal wetlands - in MDCs, people deliberately settle on
floodplains and then expect dams, and
levees to protect them
NOTE: in U.S. 10 million homes and businesses (valued at $1 trillion) are located on floodplains
37
Q
Case Study: Floodplains of Bangladesh
A
- dense population
> one of the world’s poorest and most
densely populated countries (147 million
people in area the size of Wisconsin) - located on coastal floodplain
- moderate annual floods maintain fertile
soil - “great” floods used to occur every 50
years - increase frequency of large floods since
the 1970s - changes in the Himalayan watershed ->
increased flooding:
> population growth
> deforestation (uphill)
> overgrazing
> unstable farming on hilly slopes
> destruction of coastal wetlands
-> Bangladesh’s poor have cleared
mangrove forests (for fuel wood) ->
increased flooding because swamps
absorb water
-1998 flood:
> covered 2/3 of Bangladesh’s land area
for 9 months
> leveled 2 million homes
> drowned approximately 2,000 people
> left 30 million people homeless
> destroyed 25% crops -> led to
thousands of deaths by starvation - 2002 flood:
> left 5 million homeless - dangers from cyclones and storm surges
> since 1971, 17 cyclones have hit area
> 1970 storm: 1 million people drowned
> 1991 storm surge: killed 139, 000 people
38
Q
Reducing Flood Damage
Solutions
A
- prevention
> preserve forests on watershed
> preserve and restore wetlands in
floodplains
> tax development on floodplains
> use floodplains primarily for recharge
aquifers, sustainable agriculture and
forestry
- control
> strengthen and deepen streams
(channelization)
> build levees or flood walls along streams
> build dams
39
Q
1973: U.S. Federal Flood Disaster Protection Act
A
- requires all local governments to adopt
floodplain development regulations in order
to be eligible for federal flood insurance - denies federal funding to proposed
construction projects in designated flood
hazard areas - federal flood insurance program
underwrites $185 billion in policies
because private insurance companies are
not willing to insure people who live in
flood plains
NOTE: many environmentalists feel that it would make more sense for the government to buy back the land that floods regularly rather than making disaster payments
OR: should we adopt a “LIVE AT YOUR OWN RISK” policy with no federal flood insurance
40
Q
Solutions: Increasing Freshwater Supplies
A
- dams
- watershed transfer
- tapping groundwater
- desalination
- water conservation/curbing waste
41
Q
Trade-offs of Large Dams and Reserviors
A
- provides irrigation water above and below
dam - provides water for drinking
- reservoir useful for recreation and fishing
- can produce cheap electricity (hydro-
power) - reduces downstream flooding
- flooded land destroys forests or cropland
and displaces people - $$$ to build
- large losses of water through evaporation
- deprives downstream cropland and
estuaries of nutrient rich soil - risk of failure and devastating downstream
flooding - disrupts migration and spawning of some fish
42
Q
Case Study: China’s Three Gorges Dam
A
- “Great Wall across the Yangtze”
- will be the world’s largest hydroelectric
dam and reservoir
> dam - 1.2 miles long
> reservoir - 370 miles long - will be completed in 2013
- cost $25 billion
- will displace 1.9 million people
- will generate the electrical equivalent of 20
coal pr nuclear power plants - will decrease downstream flooding (which
has killed 500,000 people during past 100
years)
43
Q
TRADE OFFS
China’s Three Gorges Dam
A
-advantages
> will generate about 10% of china's
electricity
> reduces dependence on coal
> reduces air pollution
> reduces CO2 emissions
> reduces chances of downstream flooding
for 16 million people
> reduces river sitting below dam by
eroded soil
> increases irrigation water for cropland
below dam
- disadvantages
> floods large areas of cropland and
forests
> displaces 1.9 million people
> increases water pollution because of
reduced water flow
> reduces deposits of nutrient-rich
sediments below dam
> increases saltwater introduced into
drinking water near mouth of river
because of decreased water flow
> disrupts spawning and migration of
some fish below dam
> high cost
44
Q
Case Study: Aral Sea Disaster
A
- large-scale water transfers in dry central
Asia (Uzbekistan and Kazakhstan - former
Soviet Union) - since 1960, water was diverted from Aral
sea and 2 feeder rivers for irrigation canal -
8– miles long - world’s longest irrigation canal - 800 miles
- salinity - increase 3x
-surface area - decreased 54% - volume - decreased by 15%
- 14.000 square miles of human-made salt
desert - flash extinctions and loss of fishing
industry
> 60,000 people unemployed - wetland destruction and wildlife - loss of
50% of all bird and animal species - “salt rain”
> wind blown salt -> kills crops
> salt settling on glaciers in the
Himalayas -> accelerating melting - climate changes
> decreased moderating effect of sea ->
hotter summers, colder winters
> less rain
> shorter growing season - increased use of pesticides and fertilizers
by farmers -> groundwater contamination
-> increased infant mortality and cancers - 20-50% decreased crop yeild
45
Q
TRADE OFFS
Withdrawing groundwater
A
- advantages
> useful for drinking and irrigation
> available year-round
> exists almost everywhere
> renewable if not over-pumped or
contaminated
> no evaporation losses
> cheaper to extract than most surface
waters
- disadvantages
> aquifer depletion from over-pumping
> sinking of land (subsidence) for
over-pumping
> aquifers polluted for decades or
centuries
> saltwater intrusion into drinking water
supplies near coastal areas
> reduced water flows into surface waters
> increased cost and contamination from
deeper wells
46
Q
Case Study: Ogallala Aquifer
A
- world’s largest known aquifer
- mid-western U.S. - 8 states (South
Dakota, Nebraska, Kansas, Colorado,
Wyoming Oklahoma, New Mexico, Texas) - fossil aquifer - filled during last ice age
- being pumped 8-10x faster than natural
recharge rate - transformed prairie land (with little rain) ->
productive farmland that produces 20% of
agricultural output ($32 billion/year) - depletion is encouraged by government
subsidies to farmers to grow “thirsty”
crops, and not to improve efficiency of
irrigation
NOTE: of all the water from the Ogallala aquifer was on the surface, it would cover all 50 stats with 1.5 feet of water
47
Q
Case Study: James Bay Watershed Transfer
A
- involved creating 600 dams to alter, and
even reverse, the flow of 19 giant rivers - would flood areas utilized by Cree and
Inuit tribes - phase 2 was postponed due to opposition
and the fact that phase 1 created more
electricity than could be sold
48
Q
Benefits of Reducing Water Waste
A
- reducing waste to 15% will allow us to meet most of the world's water demands for the foreseeable future - decrease burden on waste water plants - decreased need for dams and water transfer projects (will disrupt fewer habitats and displace less people) - slow groundwater depletion - save $ - save energy
49
Q
Reducing Irrigation Water Waste
Solutions
A
- line canals bringing water to irrigation
ditches - irrigate at night to reduce evaporation
- monitor soil moisture to add water only
when necessary - grow several crops on each plot of land
(poly-culture) - encourage organic farming
- avoid growing water-thirsty crops in dry
places - irrigate with treated urban waste water
- import water-intensive crops and meat
50
Q
Reducing Water Waste
Solutions
A
- redesign manufacturing processes to use less water - recycle water in industry - landscape yards with plants that require little water - use drip irrigation - fix water leaks - use water meters - raise water prices - use water-less composting toilets - require water conservation in water-short cities - use water-saving toilets, shower-heads, and front-loading clothes washers - collect and reuse household water to irrigate lawns and non-edible plants - purify and reuse water for houses, apartments, and office buildings
51
Q
WHAT CAN YOU DO?
Water Use and Waste
A
- use water-saving toilets and faucet
aerators - shower instead of taking baths, and take
short showers - repair water leaks
- turn off sink faucets while brushing teeth,
shaving, or washing - wash only full loads of clothes or use the
lowest possible water- level setting for
smaller loads - use recycled (gray) water for watering
lawns and household plants and for
washing cars - wash a car from a bucket of soapy water,
and use the hose for rinsing only - if you use a commercial car wash, try to
find one that recycles water - replace your lawn with native plants that
need little if any watering - water lawns and yards in the early
morning or evening - use drip irrigation and mulch for gardens
and flowerbeds
52
Q
Benefits of Flooplains
A
- fertile soil -> productive farmland
- nearby rivers for transportation and
recreation - flatland’s for urbanization and farming
- recharge groundwater
- ample water for irrigation
- highly productive wetlands
53
Q
Dangers of Floodplains and Floods
A
- deadly and destructive
- failing dams and water diversion
- Hurricane Katrina and the Gulf Coast
> removal of coastal wetlands - in MDCs, people deliberately settle on
floodplains and then expect dams, and
levees to protect them
NOTE: in U.S. 10 million homes and businesses (valued at $1 trillion) are located on floodplains
54
Q
Case Study: Floodplains of Bangladesh
A
- dense population
> one of the world’s poorest and most
densely populated countries (147 million
people in area the size of Wisconsin) - located on coastal floodplain
- moderate annual floods maintain fertile
soil - “great” floods used to occur every 50
years - increase frequency of large floods since
the 1970s - changes in the Himalayan watershed ->
increased flooding:
> population growth
> deforestation (uphill)
> overgrazing
> unstable farming on hilly slopes
> destruction of coastal wetlands
-> Bangladesh’s poor have cleared
mangrove forests (for fuel wood) ->
increased flooding because swamps
absorb water
-1998 flood:
> covered 2/3 of Bangladesh’s land area
for 9 months
> leveled 2 million homes
> drowned approximately 2,000 people
> left 30 million people homeless
> destroyed 25% crops -> led to
thousands of deaths by starvation - 2002 flood:
> left 5 million homeless - dangers from cyclones and storm surges
> since 1971, 17 cyclones have hit area
> 1970 storm: 1 million people drowned
> 1991 storm surge: killed 139, 000 people
55
Q
Reducing Flood Damage
Solutions
A
- prevention
> preserve forests on watershed
> preserve and restore wetlands in
floodplains
> tax development on floodplains
> use floodplains primarily for recharge
aquifers, sustainable agriculture and
forestry
- control
> strengthen and deepen streams
(channelization)
> build levees or flood walls along streams
> build dams
56
Q
1973: U.S. Federal Flood Disaster Protection Act
A
- requires all local governments to adopt
floodplain development regulations in order
to be eligible for federal flood insurance - denies federal funding to proposed
construction projects in designated flood
hazard areas - federal flood insurance program
underwrites $185 billion in policies
because private insurance companies are
not willing to insure people who live in
flood plains
NOTE: many environmentalists feel that it would make more sense for the government to buy back the land that floods regularly rather than making disaster payments
OR: should we adopt a “LIVE AT YOUR OWN RISK” policy with no federal flood insurance
57
Q
Stream Pollution
A
- oxygen sag curve
> curve in the oxygen
concentration line when
degradable wastes or heat are
introduced into a stream/river
> O2 levels decrease at the point
of discharge -> reach their
lowest point in the sceptic zone
-> and then begin to increase in
the recovery zone
> the depth and width of the curve
(and therefore the time and
distance needed for the stream
to recover) depend on:
-> stream volume
-> stream flow rate
-> stream temperature
-> pH
-> volume of incoming
degradable wastes
58
Q
Pollution Prevention in Streams
A
- require cities to withdraw their
water downstream (rather than
upstream) -> force cities to clean
up their own waste
- good news
> water pollution control laws
(1970s)
-> increased the number and
improved the quality if waste
water treatment plants
-> required industries to
decrease/eliminate point
source discharge into surface
waters
--> ex. Ohio's cuyahoga river -
caught fire in 1969
- bad news
> increased pollution in LDCs
> USA has too few monitoring
stations (64% unknown)
59
Q
Lake Pollution
A
- dilution less effective than with
streams
> stratification
-> little mixing and less dilution
> low flow
-> flushing and changing water
in lakes takes a long time (1-
100 years) compared to
streams
- lakes are more vulnerable than
streams
- eutrophication - natural aging
process
> oligotrophic
( Best recovery -> least recovery )
( River -> lake -> groundwater )
60
Q
Lake Pollution - Cultural Eutrophication
A
- causes
> over nourishment of lakes with
plant nutrients as a result of
human activities (agriculture,
urbanization, sewage plants,
etc.)
- prevention
> advanced waste treatment
> ban/limit phosphates
(detergents, cleansers)
> soil conservation - prevents
nutrient-rich soil from entering
lakes
- cleanup
> dredge bottom of lakes (remove
nutrient buildup)
> pump oxygen into lakes (to
increase DO)
> remove weeds and undesirable
plant growth
61
Q
Stream Pollution
A
- oxygen sag curve
> curve in the oxygen
concentration line when
degradable wastes or heat are
introduced into a stream/river
> O2 levels decrease at the point
of discharge -> reach their
lowest point in the sceptic zone
-> and then begin to increase in
the recovery zone
> the depth and width of the curve
(and therefore the time and
distance needed for the stream
to recover) depend on:
-> stream volume
-> stream flow rate
-> stream temperature
-> pH
-> volume of incoming
degradable wastes
62
Q
Pollution Prevention in Streams
A
- require cities to withdraw their
water downstream (rather than
upstream) -> force cities to clean
up their own waste
- good news
> water pollution control laws
(1970s)
-> increased the number and
improved the quality if waste
water treatment plants
-> required industries to
decrease/eliminate point
source discharge into surface
waters
--> ex. Ohio's cuyahoga river -
caught fire in 1969
- bad news
> increased pollution in LDCs
> USA has too few monitoring
stations (64% unknown)
63
Q
Lake Pollution
A
- dilution less effective than with
streams
> stratification
-> little mixing and less dilution
> low flow
-> flushing and changing water
in lakes takes a long time (1-
100 years) compared to
streams
- lakes are more vulnerable than
streams
- eutrophication - natural aging
process
> oligotrophic
( Best recovery -> least recovery )
( River -> lake -> groundwater )
64
Q
Lake Pollution - Cultural Eutrophication
A
- causes
> over nourishment of lakes with
plant nutrients as a result of
human activities (agriculture,
urbanization, sewage plants,
etc.)
- prevention
> advanced waste treatment
> ban/limit phosphates
(detergents, cleansers)
> soil conservation - prevents
nutrient-rich soil from entering
lakes
- cleanup
> dredge bottom of lakes (remove
nutrient buildup)
> pump oxygen into lakes (to
increase DO)
> remove weeds and undesirable
plant growth
65
Q
Groundwater Pollution
A
- most susceptible to pollution -> cannot
cleanse itself
> slow flow, dilution, dispersion
> fewer bacteria
> cooler temperatures (slow down
decomposition rates)
66
Q
Sources of Groundwater Pollution
A
- underground storage tanks
> slow leak - 1 gallon/ day - can
contaminate aquifer
> chevron storage tank in California leaked
18x more oil than the Exxon Valdez
- landfills
- hazardous waste dumps
- deep well injection - disposal of liquid
hazardous waste
- industrial waste storage lagoons
67
Q
Oceans: the “Ultimate Sink”:
A
- have the ability to dilute, disperse and
degrade large quantities of waste - 2 views of ocean dumping:
> safer than incineration or land burial
> too little known about deep ocean,
would delay pollution prevention and
promote degradation
68
Q
Ocean Pollution
A
- coastal areas - highly productive
ecosystems
> bear brunt of our inputs of pollution
> occupied by 40% of population
> twice that population by 2050
> about 80% marine pollution originates
on land
> 80-90% of municipal sewage from
coastal LDCs is dumped into oceans
without treatment
> according to one study in the U.S. 25%
of all people using coastal beaches
develop ear infections, sore throats, eye
irritation, respiratory disease, or
gastrointestinal disease after swimming
(due to vast colonies of viruses found in
U.S. coastal waters) - deep ocean waters
> some capacity to dilute, disperse,
degrade pollutants
69
Q
What Pollutants are Dumped into the Ocean?
A
- dredge spoils
> scraped from bottoms of harbors and
rivers to maintain shipping channels
> filled with toxic metals
- sewage sludge
>gooey mixture of toxic chemicals,
infectious agents, and settled solids
removed fro waste water at sewage
treatment plants
- 1992 - U.S. banned dumping sewage
sludge into the ocean
70
Q
Oil Pollution in Oceans
A
- crude and refined petroleum
- sources of oil pollution:
> tanker accidents (10% - but get much
publicity) (Exxon Valdez)
> urban runoff (45%)
> normal shipping practices (35%)
-> ballast and washing tankers
> atmosphere
> oil slick spreads from sunken rig
71
Q
Effects of Oil Pollution on Ocean Ecosystems
A
- kill aquatic organisms
- volatile organic hydrocarbons
> kill larvae
> destroys natural insulation and
buoyancy - heavy oil
> sinks and kills bottom organisms
> coral reefs die
72
Q
Effects Depend On
A
- type of oil > crude recovery quicker than refined - amount of oil released - distance from shore - time of year and weather conditions - water temperature > cold water is worse - ocean curents
73
Q
Oil Cleanup Methods
A
- current methods recover no more than 15% - prevention is most effective method > control runoff > double hull tanker
74
Q
Case Study: Exxon Valdez Oil Spill
A
- march 24, 1989
- tanker went off course, hit submerged
rocks at Alaska’s Prince William sound - oil slick coated 1,000 miles of shoreline
- killed
> 300,000-645,000 birds
> 5,500 sea otters
> 300 harbor seals etc. - response: “too little too late”
- lesson: don’t drink and drive an oil tanker
75
Q
Preventing Non-point Source Pollution
A
- mostly agricultural waste
- decrease fertilizer runoff by:
> using slow-release fertilizer
> not using fertilizer on steep slopes
> planting buffer zones of vegetation
between fields and nearby waterways - decrease pesticide runoff by
> applying pesticides only when needed
> relying on biological pest controls - decrease runoff by
> planting buffers
> not locating feedlots on steep slopes
76
Q
Discharge Trading Policy
A
- proposed by EPA in 1995
- in experimental stages
- allows for permit holders to buy and sell
pollution “credits” - opponents:
> no better than the ca set for total
pollution levels in any given area
> could allow pollutants to build up to
dangerous levels in areas where credits
are bought
77
Q
Should CWA be Strengthened or Weakened?
A
- strengthening - environmentalists
> increase funding and authority:
-> to control non-point source pollution
-> for watershed planning
>improving programs to prevent and
control toxic discharges
>expanding ability of citizens to bring
lawsuits to ensure water pollution laws
are enforced - weakening - industry, farmers, state and
local officials
> too $$$
> too restrictive
> unnecessary to test for all water pollution
78
Q
Sewage Treatment Systems
A
- rural and suburban areas - septic tank
(25% of all US homes have septic tanks)
- urban areas - waste water treatment
plants
> primary treatment - physical process
> secondary treatment - biological
process
> chlorination - bleaching and disinfection
79
Q
Treating Waste Water in Urban Areas
A
- water -> sewer pipes -> sewage treatment center - best scenario: separate lines for sewage and for runoff (\$\$$) - to save $, many cities have combined systems - problem: heavy rains can cause sewer systems to overflow -> discharge untreated sewage into surface waters
80
Q
Sewage Treatment Plants
A
- 3 levels of purification:
- primary sewage treatment
- secondary sewage treatment
- tertiary/advanced sewage treatment
81
Q
Primary Sewage Treatment
A
- mechanical/physical process
- uses screens to filter out debris (large
particles - stick, rags) - suspended particles settle in settling tank
(sludge) - water is removed from top of settling
tank/lagoon and released - after primary treatment, water
> has no sand, grit
> has organic matter, dissolved salts,
bacteria, and other microorganisms
NOTE: as long as there is high DO,
bacteria will degrade organic matter
82
Q
Secondary Sewage Treatent
A
- biological process
- aerobic bacteria remove up to 90% of
biodegradable, oxygen demanding wastes - most US cities gave secondary treatment
- two types:
> trickling filters - waste water is sprayed
over crushed stones that are covered
with bacteria (spraying aerates the
water and increases the DO)
> activated sludge process - sewage is
pumped into large tank and mixed for
several hours with bacteria rich sludge
and air bubbles to increase degradation
by microorganisms
83
Q
What do they do with the sludge?
A
- incinerate
- dump into ocean
- put in landfill
- used as fertalizer
84
Q
What Wastes Remain After Primary and Secondary Treatments?
A
- 3-5% oxygen demanding wastes
- 3% suspended material
- 50% nitrates
- 70% phosphates
- 30% toxic metal compounds
NOTE: 34 east coast cities screen out
large floating pesticides and discharge
85
Q
Tertiary/Advance Sewage Treatment
A
- specialized chemical and physical
process that removes specific pollutant
that remain after primary and secondary
treatments - vary according to specific contaminant to
be removed - usually remove nitrogen and phosphorus
- very $$$ (cost 2x as much to build, 4x as
much to operate) - can be used by industry to remove
specific pollutants
86
Q
Chlorination
A
- final step in all levels of sewage treatment
- water is bleached to disinfect and remove
coloration - problem: chlorine can react with organic
matter in water to form CHC (chlorinated
hydrocarbons) which are possible
carcinogens and may damage the
nervous, immune and endocrine systems - alternatives: disinfect with UV light or
Ozone ($$$)
87
Q
Drinking Water Quality - MDCs
A
- purification of urban drinking water
- water is stored in reservoir for several days
-> improves clarity and taste, allowing
suspended matter to settle - water is pumped to a purification plant and
treated to meet government drinking water
standards
88
Q
Drinking Water Quality - MDCs
A
- poor quality drinking water -> diseases
- WHO: purify drinking water by exposing
clear plastic bottle filled with contaminated
water to intense sunlight
> heat and UV rays kill infectious
microbes in 3 hours
> paint one side of the bottle black can
improve heat absorption
> has reduced dangerous childhood
diarrhea by 30-40% - 2007 - danish company developed a $3
life-straw that purifies and filters
contaminated water
89
Q
Ecological Waste-water Treatment
A
- working with nature to treat sewage
- living machines
- tanks with increasingly complex
organisms - artificially created wetlands
