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Final

ENV1101 Final Review.doc


Department
Environmental Studies
Course Code
ENV 1101
Professor
Sonia Wesche
Study Guide
Final

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Large lakes sometimes known as inland seas (Great Lakes)
Fish species of Great Lakes adapted to open water (sturgeon, whitefish, northern
pike, alewife, bass, walleye, perch)
GROUNDWATER PLAYS KEY ROLES IN THE HYDROLOGIC CYCLE
Precipitation that does not evaporate, flow into water ways, or get taken up by
organisms infiltrates the surface
Groundwater: water that percolates downward through the soil (1/5th) of earth’s
freshwater supply
Aquifers: porous formations of rock, sand or gravel that hold water
Zone of aeration = aquifer’s upper layer, contains pore spaces partly filled with
water
Zone of saturation = lower layer, spaces completely filled with water
Water Table: boundary between the 2 zones
Below the water table all pore spaces, & fractures are completely filled; above
some water is present but not completely saturated
Recharge Zone: area where water infiltrates Earth’s surface & reaches an aquifer
Confined Aquifer (Artesian Aquifer): exists when a water-bearing porous layer of
rock, sand, or gravel is trapped between upper& lower layers of less permeable
substrate (clay); water is under pressure
Unconfined Aquifer: no impermeable upper layer to confine it, water under less
pressure, readily recharged by surface water
Groundwater becomes surface water through springs & human made wells
Groundwater flows downhill from areas of pressure to pressure
Discharge Zones: where groundwater emerges to join surface water bodies
Typical rate of groundwater flow may only be 1m per day
Ogallala Aquifer in Great Plains of the US = world’s largest known aquifer
This aquifer enabled American farmers to create a bountiful grain-producing
region
Natural Resources Canada Groundwater Mapping Program
Paskapoo Formation covers more than 10 000 km2 of southwestern Alberta
Oak Ridges Moraine (glacial deposits) cover 1900km2 provides GTA with water
Annapolis Cornwallis Valley Aquifers in Nova Scotia covers 2400 km2
WATER IS UNEQUALLY DISTRIBUTED ACCORSS EARTH’S SURFACE
Water concentration varies between and within countries
People are not distributed in accordance to water
Water is distributed unevenly in time as well (monsoons bringing ½ of India’s
annual rainfall in a few hours)
People have erected dams to store water so that it can be distributed
CLIMATE CHANGE WILL CAUSE WATER PROBLEMS AND SHORTAGES
Climate change is expected to affect fresh water & hydrologic cycle in 4 main
ways:
1. Present midlatitude rain belt will shift northward
2. Snowmelt & spring runoff will occur earlier than at present
3. There will be more evapotranspiration (earlier & longer)
4. Interior continental region will experience drier summers
Droughts will become more common, severe, extended due to temp and
precipitation in interior continental regions
Warmer river temp damage aquatic ecosystems & freshwater fish
Secondary problems: if water levels dredge channels necessary to accommodate
shipping
Dredge channels stir up & re-suspend sediments turbidity potentially
reactivating toxic chemicals
Due to sea levels saltwater intrusion into coastal groundwater aquifers &
saltwater disturbance of coastal estuaries
HOW WE USE WATER
60% of the world’s largest 227 rivers have been strongly/moderately affected by
artificial dams, canal’s & diversions
Diversion: rerouting of water from its natural river channel by means of a built
structure
Channelization: Artificial channel modifications including straightening &
concrete lining of channels
1/3 of world’s people are already affected by water scarcity (less than 1000 m2 per
person per year)
WATER SUPPLIES OUR HOUSEHOLDS, AGRICULTURE, & INDUSTRY
3 types of water use; residential/municipal, agricultural, & industrial vary
dramatically among nations
Arid climates tend to use more freshwater for agriculture
Heavily industrialized nations use a great deal for industry
Globally 70% annual fresh water allotment used on agriculture, 20% industry, 10%
residential/municipal
CHAPTER 12: FRESHWATER SYSTEMS AND WATER RESOURCES
FRESHWATER SYSTEMS
Oceans = 97.5% of Earth’s water
Fresh Water: water that is relatively pure, few dissolved salts (2.5%)
Most fresh water found in glaciers, icecaps, underground aquifers
Constantly moving through reservoirs via the hydrologic cycle
As water moves it redistributes heat, erodes mountain ranges, builds river deltas,
maintains organisms & ecosystems, shapes civilizations, gives rise to personal
conflicts
RIVERS, STREAMS AND WIND THROUGH LANDSCAPES
Rain, snowmelt, springs runs downhill & streams, rivers, or brooks
Streams, rivers, brooks rivers oceans
Tributary: smaller river flowing into a larger one
Drainage Basin or Watershed: area of land drained by a river & its tributaries
Rivers shape the landscape through which they run, eats away at shores, eroding
soil from the bank
Sediment deposited along the inside of the bend where water currents are weaker
river bends become exaggerated in shape
Extreme bends oxbow water erodes a shortcut from one end of the loop to the
other (isolated U shape)
Floodplain: area of land nearest a river’s course that is flooded periodically
Floodplain soils are especially fertile due to frequent deposition of silt
Agriculture thrives in floodplains & riparian (riverside) forests are
productive/species rich
Algae & detritus support many types of invertebrates (crayfish, water beetles)
Dragonflies, mayflies, mosquitoes develop as larvae in streams & rivers
Fish eat aquatic insects & birds eat fish
WETLANDS INCLUDE MARSHES, SWAMPS, & BOGS
Wetlands: combine elements of freshwater & dry land (rich & productive)
Marshes: shallow water allows plants to above the water’s surface (cattails &
bulrushes)
Swamps: shallow water rich in vegetation, in forested areas (also created when
beavers build dams across streams)
Bogs: ponds thoroughly covered with thick floating mats of vegetation (Stage in
aquatic succession)
Wetlands are extremely valuable as habitat for wildlife
Ecosystem services: slow runoff, flooding, recharging aquifers, filtering
pollutants
Wetlands drained for agriculture
Over ½ of all wetlands lost since European colonization
Potholes region of Canadian Prairies = most highly productive agricultural region
of the country
LAKES AND PONDS ARE ECOLOGICALLY DIVERSE SYSTMES
Lakes/ponds = bodies of open standing water
Types of life vary with depth & distance from shore
Littoral Zone: region ringing on the edge of a water body
Water is shallow enough that aquatic plants grow from mud & reach above water’s
surface
Nutrients & productive plant growth of littoral zone makes it rich in invertebrates
(insect larvae, snails, crayfish)
Fish, turtles, amphibians feed on invertebrates
Benthic Zone: extends along bottom of the entire water body from shore to the
deepest point
Many invertebrates live in the mud on the bottom, feeding on detritus or prettying
on one another
Limnetic Zone: open portion of lake/pond away from shore where sunlight
penetrates
Light in photic zone enables photosynthesis & plant growth
Limnetic zone supports phytoplankton, which supports zooplankton, which are
eaten by fish
Sunlight intensity with depth
Turbidity affects depth of zone; clear water allows sunlight penetrate deeply
Profundal Zone: below limnetic zone, the volume of water that is in the aphotic
zone, depth below which sunlight does not reach
Lacks plant life in dissolved oxygen, supports fewer animals
Benthic zone may be photic or aphotic but profundal is strictly aphotic
Ponds/lakes change over time b/c streams and runoff bring in sediment and
nutrients
Ogliotrophic: lakes/ponds which have nutrient & oxygen conditions, may
slowly give way to eutrophic conditions
Eutrophic: nutrient, oxygen conditions
Eventually water bodies may fill in completely through process of aquatic
succession
As lakes/ponds change, species of fish, plants, & invertebrates change as well
Led to tense international incident btw US & Mexico in 1970 agreements on
water reallocation
Aral Sea: 4th largest lake on earth, lost more than 4/5 volume in 45 yrs
Border of Uzbekistan & Kazakhstan
INEFFICIENT IRRIGATION WASTES WATER
Green revolution irrigation (70%> 1960)
Expansion of irrigated agriculture kept pace with population growth
Irrigated area per capita stable for 4 decades around 460m2
Irrigation can more than double crop yields
World = 274 million hectares of irrigated cropland = 18% world farmland but
yield 40% agricultural produce (60% of global grain)
Only 45% irrigation water taken up by crops
Fields are liberally flooded may evaporate
Over irrigation waterlogging & salinization
Inefficient irrigation methods in arid regions use up large amounts of water for
little gain
15-35% water withdrawals for irrigation considered unsustainable
WETLANDS HAVE BEEN DRAINED FOR A VARIETY OF REASONS
Governments have encouraged efforts to drain wetlands for farmland
In 1930s government wanted to drain entire Everglades
Attitude changed with rise of environmental movement 1970s
1971 international agreement reached in Ramsar Iran concerning documentation &
protection of wetlands (Ramsar Convention, Convention on Wetlands of
International Importance)
Mission of the treaty = conservation & wide use of all wetlands through local,
regional, & national actions & international cooperation
90% original wetlands in Canada lost
Canada as a whole still ahs the largest area of wetlands of any country
Wetlands are valuable ecosystems
Loopholes, differing laws, development pressures, debate over legal definition of
wetlands wetlands being lost
WE ARE DEPLETING GROUNDWATER
More easily depleted than surface water because aquifers recharge slowly
160km2 more water extracted annually than being replaced
1/3 human population relies on groundwater for needs (26% CAN)
Mexico, India, China water tables falling 1-3 m/year
Groundwater overpumped in coastal areas saltwater intrudes into aquifers
Aquifers lose water substrate become weaker/less capable of supporting
overlying strata land surface above may subside
Cities (Venice, Bangkok, Shanghai) slowly sinking
Downtown Mexico City sunk over 10m since Spanish arrival
Sinkholes: areas where ground gives way with little warning, occasionally
swallowing people’s homes
Once ground subsides soil can under compaction (being compressed and losing
porosity that enabled it to hold water)
Permanent wetlands where water tables are high enough to reach the surface
Water tables drop = wetland ecosystems dry up
OUR THIRST FOR BOTTLED WATER SEEMS UNQUENCHABLE
3/10 Canadian households use bottled water as main source of domestic drinking
water
Proportion of households dependent on bottled water with household income
University-educated households less likely to consume bottled water
Much bottled water is ordinary tap water
Fewer checks on bottled water & bottling process than on municipal water supplies
Concerns from Health Canada about chemicals that might leach into water from
plastic bottles under some circumstances
WILL WE SEE A FUTURE OF WATER WARS?
Depletion of fresh water shortages resource scarcity conflict
Water’s role in regional conflicts as human population in water-poor areas &
climate alters regional patterns of precipitation
Transboundary waterways cross/flow along national borders; 45%
Key element in hostilities among Israel & Palestine
India resolved water disputes with Pakistan, Bangladesh, Bhutan, Nepal
US & Canadian agreements governing the Great Lakes
SOLUTIONS TO DEPLETION OF FRESH WATER
Human population growth, expansion of irrigated agriculture, industrial
development doubled annual freshwater use (19602000)
SOLUTIONS CAN ADDRESS SUPPLY OR DEMAND
Can either supply or demand
demand include conservation & efficiency measures
demand is difficult politically in the short term but necessary in the long term
International aid agencies fund demand-based solutions>supply based
Consumptive use = when water is removed from an aquifer or surface body of
water and is not returned
Much of agricultural irrigation, industrial & residential uses is consumptive
Non-consumptive use of water does not remove/temporarily removes water
Using water to generate electricity at hydroelectric dams = non-consumptive use
WE HAVE ERECTED THOUSANDS OF DAMS
Dams: any obstruction placed in a river/stream to block the flow of water so that
water can be stored in a reservoir
Built to prevent floods, provide drinking water, facilitate irrigation, generate
electricity
Worldwide >45 00 large dams (>15m high) across rivers in more than 140 nations
Gardiner Dam in Saskatchewan is the largest in Canada in terms of water-holding
capacity
Mica Dam BC = tallest
Hoover & Glen Canyon dams (hoover = most iconic)
CHINA’S THREE GORGES DAM IS THE WORLD’S LARGEST
On the Yangtze River
186m high & 2 km wide
Completed in 2006, completely filled in 2010
Reservoir reached 616 km in length holding more than 38 trillion litres of water
Enable boats & barges to travel farther upstream, flood control, generate
hydroelectric power to replace dozens of large coal/nuclear plants
Cost 25 billion, reservoir flooded 22 cities, displaced 1.24 million
Filling of reservoir submerged 10 000 year old archaeological sites, productive
farmlands, & wildlife habitat
Slows river flow suspended sediment settling behind the dam
River downstream is deprived of sediment tidal marshes at the mouth is eroding
away, leaving Shanghai with a degraded coastal environment & less coastal land to
develop
Pollutants will be trapped making water undrinkable
High levels of bacteria found in the water as soon as building began
Chinese government plan to sink 5 billion in sewage treatment & waste disposal
facilities
St. Lawrence Seaway = 50 yrs of discussion but 5 yrs to complete
SLS = series of canals that connect the Great Lakes to the Atlantic Ocean (follows
route of St Lawrence river)
Construction of SLS displaced 6500 people, villages were flooded, historically
important battlefields from War of 1812 flooded
SOME DAMS ARE NOW BEING REMOVED
Feeling that cost<benefit of dams pushing for removal
By removing dams we can restore riparian ecosystems, re-establish valuable
fisheries & revive river recreation (fly-fishing, rafting)
Decommissioning dams because of costly repairs
500 removed in US in recent years
Dam removal provides opportunities for scientific study of the response of the
river & aquatic communities
DIKES AND LEVEES ARE MEANT TO CONTROL FLOODS
Flood prevention why we control movement of freshwater
Flooding is a natural, normal process caused by snowmelt/heavy rain
Floodwaters spread nutrient-rich sediments over large areas benefiting natural
systems & human agriculture
Short term = damage to farms, homes & property of people living on floodplains
Dikes: built along banks of rivers; holds rising water in main channels, many are
small & locally built, some are massive
Levees = long raised mounds of earth along banks of rivers
Flood diversion wall that protects Winnipeg from Red River
Structures can worsen floods force water to stay in channels &
accumulatebuilding up energy occasional catastrophic overflow
WE DIVERT – AND DEPLETE – SURFACE WATER TO SUIT OUR NEEDS
Diversion = process of moving water from its channel/modifying its flow for the
purpose of using it elsewhere
Colorado River; water piped through a mountain tunnel, down the Rockies’ eastern
slope to supply Denver
More removed for Vegas & farmland, water proceeds downriver
Water reaches Parker Dam on the California-Arizona state line
Large amounts of water diverted into the Colorado River Aqueduct, brings water
to millions of people in LA & San Diego
Arizona draws water transporting it in the canals of the Central Arizona Project
Imperial Dam water diverted into Coachella & Canals
Water left in the Colorado River goes to the Gulf of California & Mexico; some
days there is not water left
Reduction in flow altered ecology of lower river

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NUTRIENT POLLUTION
Nutrient pollution from fertilizers/other sources eutrophication & hypoxia in
coastal marine-areas
Phosphorous spurs growth in freshwater systems
Excess phosphorous algae & aquatic plant growth rates/population
Growth provides oxygen & good but deprives deeper-water plants of sunlight
Dead algae = food for decomposing bacteria
Decomposing requires oxygen dissolved oxygen
O2 can too low to support fish/shellfish
Eutrophication = natural system but runoff can dramatically rates it occurs
nutrient pollution by treating waste water, fertilizer application, planting
vegetation to nutrient uptake & purchase phosphate-free detergent
PATHOGENS AND WATERBORNE DISEASE
Disease causing organisms can enter drinking water supplies when contaminated
with human/animal waste
Fecal coliform bacteria indicates water contaminated by waste
Coliform not pathogenic themselves but indicates that water might hold other
pathogens (giardiasis, typhoid, hepatitis A)
Biological pollution by pathogens = more human health problems than any other
type of water pollution
87% world population have access to safe water
4/5th people without sewer/sanitation facilities = rural areas
Conditions 5 million deaths per year
Treating sewage = approach to waterborne pathogen risk
Public education, personal hygiene, government enforcement of regulations to
ensure cleanliness of food production, processing, distribution
TOXIC CHEMICALS
Waterways polluted w toxic organic substances (pesticides, petroleum, synthetic
chemicals)
Can poison animals, plants, alter aquatic ecosystems
Human health problems = cancer
Toxic metals (arsenic, lead, mercury) & acids (acid rain/drainage from mine sites)
= adverse impacts on health & environment
More stringent regulations can help toxic inorganic chemicals
SUSPENDED MATTER
Floods build fertile farmland but sediment & suspended matter can impair aquatic
ecosystems
Mining, clear cutting, land clearing for development, careless cultivation expose
soil to wind & water erosion
Some water bodies (China’s yellow river) are naturally sediment-rich
Clear-water river + heavy eroded sediment = change in aquatic habitat
THERMAL POLLUTION
Water’s ability to hold dissolved O2 as temp
Withdrawal of water from river to cool industrial facility = transfer of heat energy
from facility back to river
Surface water temp by removing streamside vegetation that shades water
Too little heat may favour cold-loving invasive species over endangered native
species
Water at bottoms of reservoirs colder than at surface, water released from dam =
temp
WATER POLLUTION COMES FROM POINT AND NON-POINT SOURCES
Point Sources: water pollution emitted from discrete locations (factory, sewer pipe)
Non-Point Sources: pollution emitted from multiple cumulative inputs over larger
areas (farms, city streets, residential neighbourhoods)
Fertilizers, pesticides, salt to roads, changing car oil contribute to non point
sources
non-point source water pollution limit development on watershed land
surrounding reservoirs
SCIENTISTS USE SEVERAL INDICTORS OF WATER QUALITY
Water Quality: physical, chemical, biological properties to water
Biological: presence of fecal coliform bacteria/other pathogens, algae, aquatic
invertebrates
Chemical: pH, taste, odour, hardness, O2
Hard water = naturally high concentrations of calcium & magnesium (prevents
soap from lathering & leaves chalky deposits when boiled
Physical: turbidity (density of suspended particles in water sample), colour,
temperature
Tannins causes streams to run the colour of iced tea (decomposing leaf litter)
GROUNDWATER POLLUTION IS A SERIOUS PROBLEM
Groundwater polluted by from industrial & agricultural practices
Hidden from view, difficult to monitor
More difficult to manage; rivers flush pollutants quickly, groundwater retains
contaminants till they decompose
Demand based solutions better economic returns, cause less ecological/social
damage
To supply people transport water through pipes & aqueducts from areas where it
is more plentiful or accessible
Water-poor regions forcibly appropriated water from communities too weak to
keep it for themselves
LA & California; LA diverted more than 14m over 40 yrs from Mono Lake
Caused salt concentrations to double & aquatic communities to suffer
DESALINATION “MAKES” MORE WATER
Desalination: removal of salt from seawater or other water of marginal quality
One method mimics the hydrologic cycle by hastening evaporation from
allotments of ocean water with heat then condensing the vapour
Another method: forcing water through membranes to filter out salts (reverse
osmosis)
>7500 desalination facilities operating worldwide, most in Middle East
Saudi Arabia = largest plant 485 million litres of fresh water every day
Desalination is expensive & requires large inputs of fossil fuel energy, generates
concentrated salty wastes
AGRICULTURAL DEMAND CAN BE REDUCED
Farmers can efficiency by lining irrigation canals (prevent leaks, levelling fields
to minimize runoff, adopt efficient irrigation methods
Low-pressure spray irrigation directs water downward toward plants
Drip irrigation 90% efficient, cut water use 50% & yields 20-90%
Choosing crops to match land/climate can save water
Cotton, rice, alfalfa planted in arid areas w government subsidized irrigation
As a result of subsidies, true cost of water is not part of the cost of growing crops
Eliminating subsidies could water use
Selective breeding & genetic modification can result in crop varieties that require
less water
WE CAN LESSEN RESIDENTIAL AND INDUSTRIAL WATER USE IN MANY
WAYS
amount of meat we eat because meat requires more water inputs that grain or
vegetables
Install low-flow faucets, showerheads, washing machines, toilets
Automatic dishwashers use less water than washing dishes by hand
Water lawn at night
Xeriscaping: landscaping with plants that are well adapted to a dry environment
Manufactures shifting to processes that use water cost
Some cities recycle municipal waste water for irrigation & industrial uses/
capturing excess runoff & pumping into aquifers
Patching leaks in pipes
ECONOMIC APPROACHES TO WATER CONSERVATION ARE BEING
DEBATED
Market-based strategies to achieve sustainable water end government subsidies
of inefficient practices
Worry that making water fully priced = less available to the poor
Industrial use of water can be 70x as profitable as agricultural use, market forces
may favour uses that would benefit wealthy & industrialized people, companies at
the expense of the poor
Privatization of water supplies
Past 20yrs public water systems partially/wholly privatized (construction,
maintenance, management, ownership transferred to private companies)
Done with the hope of efficiency but many firms are not motivated to allow
equitable access to water
Rural residents without water from private vendors & end up paying 12x more
than those connected to public supplies
Decentralization of control over water may help conserve water
FRESHWATER POLLUTION AND ITS CONTROL
Quantity & distribution of freshwater = environmental & social challenge
Quality of water = environmental & human health dilemma
World Commission on Water > ½ major rivers are seriously depleted &
polluted, threatening health & livelihood of people who depend on them
WATER POLLUTION TAKES MANY FORMS
Pollution: release of matter/energy that causes undesirable impacts on health &
well-being of humans/other organisms
Pollution can be physical, chemical, biological & affect water, air, soil
Can cause diverse impacts on aquatic ecosystems/human health
Several types of pollution

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Restricting pollutants on lands above aquifers shift pollution elsewhere
Consumer choice; phosphorous-free detergents, environmentally friendly products
Become involved in protecting local waterways
Volunteers collect data & help agencies safeguard the health of water bodies
WASTE WATER AND ITS TREATMENT
Waste Water: water used by people in some way (sewage, showers, sinks, washing
machines, dishwashers, manufacturing/cleaning, business/industries, stormwater
runoff)
Natural systems can processes moderate amounts of waste water
MUNICIPAL WASTEWATER TREATMENT INVOLVES SEVERAL STEPS
Septic Systems: waste water from house underground septic tank solids/oils
separate water goes downhill to drain field of perforated pipes in gravel filled
trenches underground microbes decompose waste water
Solid waste needs to be pumped from septic tanks to landfills
Most popular in rural areas
Densely populated areas = municipal sewer systems carry waste water to
centralized treatment locations
Pollutants removed by physical, chemical & biological means
Primary treatment physical removal of contaminants in settling tanks/clarifiers
(60% suspended solids removed)
Secondary treatment water stirred/aerated so aerobic bacteria degrade organic
pollutants (90% removed)
Clarified water treated with chlorine & UV light to kill bacteria
Effluent: treated water
Effluent piped into rivers/oceans
“Reclaimed” water used tor lawns/golf courses, irrigation, industrial purposes
(cooling water in power plants)
Sludge (solid waste) sent to digesting vats microorganisms decompose matter
biosolids (wet solution) dried & decomposed in a landfill, incinerated or used as
fertilizer
Methane-rich gas created by decomposition sometimes burned to generate
electricity
ARTIFICIAL WETLANDS CAN AID TREATMENT
Natural wetlands already perform water purification
Wastewater treatment engineers manipulate wetlands, & construct wetlands de
novo to use them as tools to cleanse water
Constructed (Artificial) Wetlands: treating waste water & polluted runoff
Nova Scotia & Nova Scotia Agricultural College constructing test series of 3
artificial wetlands used to filter agricultural runoff from livestock
Wastewater that has gone through primary treatment @ conventional facility
pumped into wetland microbes in algae & aquatic plants decompose remaining
pollutants
Water cleansed in wetland released into waterways
Constructed wetlands = havens for wildlife & areas for human recreation
CHAPTER 14: ATMOSPHERIC SCIENCE AND AIR POLLUTION
THE ATMOSPHERE AND WEATHER
Atmosphere: thin layer of gases that surrounds Earth
We live at the bottom of this layer, provides O2, absorbs hazardous solar radiation,
burns incoming meteors, transports/recycles water& nutrients, moderates climate
Atmosphere = 78% nitrogen; 21% oxygen, 1% argon & other gases
Permanent gases = stable concentrations (Ne, He, H2, Xe)
Variable gases = variable concentrations (H2O vapour, CO2, CH4(methane), nitrous
oxide N2O, O3, CFCs)
Atmosphere becoming dominated by CO2, N2, CO & H2
Before autotrophic microbes emitted O2 as a by product of photosynthesis, today
human activity is changing quantities of atmospheric gases (CO2, CH4, O3)
THE ATMOSPHERE IS LAYERED
Atmosphere = thin coating 1/100th of earth’s diameter
4 layers measured by differences in temperatures, density & composition
Troposphere: bottom most layer
Provides air needed to live
Movement of air responsible for weather
11km high
Contains ¾ of atmospheric mass due to dense air
Air temperature 6oC/ Km in altitude
Tropopause = cap limiting mixing between troposphere & stratosphere
DDT still found in aquifers in NA even though it was banned 40yrs ago
Chemicals break down more slowly in aquifers than in surface water or soils
Contains less dissolved oxygen, microbes, minerals, & organic matter,
decomposition is slower
Herbicide alachlor by ½ after 20 days in soil but 4yrs in groundwater
THER ARE MANY SOURCES OF GROUNDWATER POLLUTION,
INCLUDING SOME NATURAL SOURCES
Some chemicals toxic in high concentrations (aluminum, fluoride, nitrates,
sulphates) occur naturally in groundwater
Water in aquifers surrounded by rocks
Ca & Mg from rocks
Poisoning of Bangladesh’s wells by arsenic = natural contamination
Industrial, agricultural & urban wastes leach through soil & seep into aquifers
Pathogens/pollutants enter groundwater through improperly designed wells & from
pumping liquid hazardous waste below ground
Leakage from underground tanks (septic, oil/gas, industrial chemicals) pollute
groundwater
Without adequate corrosion protection > ½ underground gasoline storage tanks
pollutes groundwater
Can be expected to start leaking at 15yrs
1L gasoline can contaminate 1 million L groundwater
Once an aquifer is contaminated it is very difficult to clean
Nitrates from fertilizers leach into groundwater in agricultural areas
Nitrate in drinking water: miscarriages, cancers, “blue baby syndrome” ( oxygen
carrying capacity of infant’s blood)
Agriculture contributes to pathogens with animal wastes
Walkerton Ontario; 2000 groundwater contaminated w Escherichia coli (E. coli)
2 thousand ill; 7 dead
LEGISLATIVE AND REGULATORY EFFORTS HAVE HELPED REDUCE
POLLUTION
Citizen activism & government response 1960s-70a fundamental changes in
environmental practices & legislation
Illegal to discharge pollution from a point source w/o permit
Standards set for industrial waste water & contaminated levels in surface water
funded construction of sewage treatment plants
Canadian legislation enacted/enforced @ provincial level, federal government sets
guidelines (Environmental Protection Act)
CEPA regulates interprovincial transfers of hazardous materials
Fisheries Act (federal) illegal to damage any water body that serves as a habitat
for fish (mining companies exempt in some instances)
Point-source pollution
International Joint Commission; The Great Lakes Water Quality Agreement &
International Boundary Waters Treaty Act
1970s Great Lakes badly polluted with waste water, fertilizer, toxic chemicals
Today; toxic chemicals, phosphorous runoff, bird populations
Lake Eerie = world’s largest walleye fishery
Sediment population still heavy, PBCs & Mercury still settle on lakes from air
Fish not always safe to eat
Japan, Singapore, China, South Korea legislation, regulation, enforcement,
investment in wastewater treatment improve water quality
Non-point-source pollution, eutrophication, acid precipitation = major challenges
WE TREAT OUR DRINKING WATER
Treating of drinking & waste water = mainstream practices in developed nations
Health Canada water standards;
Microbiological parameters (viruses, bacteria, protozoa, turbidity)
Chemical & physical (health & esthetic guidelines)
Radilogical parameters
Over 80 characteristics considered
Some have numerical standards associated with them
Guidelines set by Federal-Provincial-Territorial Committee on Drinking Water
(Health Canada, Environment Canada, Council of Environment Ministers,
Canadian Advisory Council on Plumbing)
Water from reservoir/aquifer treated with chemicals to remove particulate
matter passed through sand, gravel, charcoal filters disinfected with small
amounts of chlorine
BETTER TO PREVENT POLLUTION THAN TO MITIGATE THE IMPACTS
AFTER IT OCCURS
End-of-Pipe: treatment/clean up after pollution
Filtering groundwater pre distribution is expensive
Pumping water out of, treating, then back into a aquifer takes a long time
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