Ontario and the Great Lakes.docx

15 Pages
Unlock Document

Geography 2011A/B
Wendy Dickinson

Lake Levels The International Joint Commission:  The binational agency established under the Boundary Waters Treaty of 1909 between Canada and the U.S  Responsible for regulation of flows on the St. Mary’s and the St. Lawrence Rivers  Lake Michigan flows to Lake Huron through the Straits of Mackinac.  Michigan and Huron standing at the same elevation.  No artificial controls on the St. Clair and Detroit Rivers that could change the flow from the Michigan-Huron Lakes system into Lake Erie.  Outflow of Lake Erie via the Niagara River is uncontrolled  except for some diversion through the Welland Canal  Further regulation by engineering systems could not be justified in light of the cost and other impacts *** one inch (two and a half centimeters) of water on the surface of Lakes Michigan and Huron amounts to more than 36 billion cubic meters of water (about 1,260 billion cubic feet).*** Lake Processes  Stratification: layering of water in the lakes due to density changes caused by changes in temperature.  The density of water increases as temperature decreases until it reaches its maximum density at about 4° Celsius (39° Fahrenheit)  Thermal stratification, or the tendency of deep lakes to form distinct layers in the summer months.  Deep water is insulated from the sun and stays cool and more dense, forming a lower layer called the 'hypolimnion' - High productivity just above the hypolimnion - Hypolimnion has less sunlight and is therefore less productive - Hypolimnion lacks oxygen in central basin of lake erie b/c of decomposition o organic matter  Surface layer called the 'epilimnion'. - Supports most life in lake - Rich in oxygen  Thermocline (middle layer) develops as summer progresses and temperature differences increase between the layers in which a rapid transition in temperature occurs.  Fall  surface waters cool, become denser and descend, displacing deep waters and causing a mixing or turnover of the entire lake  Winter  the temperature of the lower parts of the lake approaches 4° Celsius (39° Fahrenheit), while surface waters are cooled to the freezing point and ice can form.  Temperatures and densities change in spring, another turnover may occur. However, in most cases the lakes remain mixed throughout the winter  Turnover is the main way in which oxygen-poor water in the deeper areas of the lakes can be mixed with surface water  prevents anoxia  Thermal bar holds pollutants near shore, they are not dispersed to the open waters and can become more concentrated within the near shore areas. Living resources  Plant material is consumed in the water by zooplankton, which grazes the waters for algae, and on land by plant-eating animals (herbivores)  ~ 180 species of fish indigenous to the Great Lakes.  Near shore fish: smallmouth and largemouth bass, muskellunge, northern pike and channel catfish.  Open water fish: lake herring, blue pike, lake whitefish, walleye, sauger, freshwater drum, lake trout and white bass.  Erie was the most productive – warm and shallow  Superior was the least productive- deep  Overfishing, habitat destruction or the arrival of exotic or non-indigenous species, such as the lamprey and the alewife, has lost many native fish species Chapter 4: Concerns Today  Since about 1960, we realized the harsh implications of some human activities. The largest categories of impact are pollution, habitat loss and exotic species  Agricultural development, forestry and urbanization caused streams and shoreline marshes to silt up and harbor areas to become septic.  Domestic and industrial waste discharges, oil and chemical spills and the effects of mining left some parts of the waterways unfit for water supply and recreation. Pathogens  Historically, the primary reason for water pollution control was prevention of waterborne disease.  Treating drinking water by adding chlorine, as a disinfectant  Humans can acquire bacterial, viral and parasitic diseases through direct body contact with contaminated water as well as by drinking the water.  Closing affected beaches during the summer when the water is warm and when bacteria from human and animal feces reach higher concentrations.  Combined sewers contribute to contamination problems during periods of high rainfall and urban runoff  Sewage collection and treatment systems cannot handle volumes of storm and sanitary flow  untreated sewage, diluted by urban runoff, is discharged directly into waterways.  Expensive to replace combined sewers with separate sewers  Alternative s  combined sewer overflow retention for later treatment (lower costs than sewer separation)  Beach closures have become more infrequent with improved treatment of sewage effluent Eutrophication and Oxygen Depletion  Lakes characterized by biological productivity (amount of living material they support)- mostly algae  Oligotrophic- lease productive  Mesotrophic- middle  Eutrophic – most productive  Variables that determine productivity are temp. Light, depth, volume and nutrients  Temps of tributes have increased b/c of removal of shade and some thermal pollution  Nutrients/ organic material entered lake has increased with urbanization and agriculture  nutrient loading with phosphate detergents and inorganic fertilizers  Phosphates in detergents are a problem when not regulated b/c increased nutrients stimulates growth of green plants (algae) which eventually die and decompose  Organisms that decompose the plants use up the oxygen dissolved in water near bottom  Without nutrient loading oxygen levels are maintained  Biochemical oxygen demand (BOD): depletion of oxygen through decomposition of organic material - generated from discharges from treatment plants and decaying algae - big problem in central basin of Erie - As BOD increases and O2 drops certain species of fish can be killed and sludge, worms and carp replace them  Foggy water and increase in chlorophyll accompany accelerated algal growth and indicate eutrophication  Erie was firs to develop eutrophication  O2 depletion in Erie 1920s  Controlling input of phosphorus could control eutrophication  Lower layer of central Erie (hypolimnion) can become anoxic and chemical processes change “dead zone” - Western less susceptible to anoxia b/c of wind and too shallow and eastern is deeper with thicker hypolimnion  Belief that Erie was “dying” cladophors near beaches and turbid water Toxic Contaminants  The dangers of toxic substances in the natural environment were first shown through the study of pesticide DDT.  Toxic pollutants include human-made organic chemicals and heavy metals that are dangerous if chronically exposed to small amounts  risk of cancer, birth defects and genetic mutations through long-term, low-level exposure  Toxic substances tend to bio accumulate as they pass up the food chain in the aquatic ecosystem  Concentrations of chemicals such as PCBs may be so low that they are almost undetectable, in the water  Biomagnification through the food chain can increase levels in predator fish such as large trout and salmon by a million times  Health and environmental agencies in the Great Lakes states and the Province of Ontario warn against human consumption of certain fish.  Some fish cannot be sold commercially because of high levels of PCBs, mercury or other substances.  Fish consumption provides the greatest potential for exposure of humans to toxic substances found in the Great Lakes when compared with other activities such as drinking tap water or swimming  Trout from Lake Michigan will be exposed to more PCBs in one meal than in a lifetime of drinking water from the lake.  At-risk groups of concern: people who rely on fish and wildlife for a large part of their diet  Concerns that exposure to low levels of some contaminants may cause subtle effects on reproduction, development and other physiological parameters  Effects of persistent contaminants on the immune system, the nervous system, pre-natal and post-natal development, fertility and the development of cancers.  Disease rates within the Great Lakes basin are not significantly different from those in other parts of the U.S. or Canada.  Developing fetus and child, the elderly and people whose immune systems are already suppressed are more susceptible  Some of the chemicals found in the lakes have been shown to be cancer-causing agents (carcinogens) in high-dose animal studies.  DDT, one of several chlorinated organic compounds that can weakly mimic estrogen, is under investigation for potential linkages to one type of breast cancer.  TCDD, a form of dioxin, to mimic estrogen, with the potential results of feminization of sex organs in males and disruption in the development of other sexual characteristics. There are also questions about the effects of estrogen-like compounds on sperm quality. Pathways of pollution  Many pollutants are deposited from the atmosphere.  Nutrients and toxic contaminants carried and deposited in the lakes in wet and dry forms.  Atmospheric deposition of a pollutant in the Great Lakes basin was first recognized with phosphorus  PCBs volatilize out of the lakes, as well as being deposited into them from the reservoir of chemicals in air masses  Release of pollutants from sediments occurring in Niagara, St. Clair and St. Mary’s Rivers, in harbors such as Hamilton, Toronto and the Grand Calumet, and in tributaries such as the Buffalo, Ashtabula and Black Rivers.  Groundwater water slowly passes through the ground it can pick up dissolved materials that have been buried or soaked into the ground. Loadings to a closed system  All pathways end in the lakes.  Understand the total loading of pollutants to each lake from all pathways. (first recognized for phosphorus, as reflected in the Great Lakes Water Quality Agreement.)  Lakewide Management Plans called for in the Agreement can provide the 'schedule of load reductions of Critical Pollutants that would result in meeting Agreement Objectives. Control of Pollutants  High degree of control for point sources (direct discharges)  nonpoint sources hard to control because of diffuse nature, episodic release and lack of institutional arrangements to support their control.  Nonpoint sources less suited to regulatory control.  public education, pollution prevention and voluntary actions are very important for non point sources  Pollution prevention focuses on eliminating pollutants before they are produced (changing production processes, feedstock’s, environmentally friendly products)  Preventive  ban the production/extraction and use of certain chemicals and metals; also prevent the direct discharge of chemicals into waterways. Bioaccumulation and Biomagnification  Phytoplankton must collect nutrients necessary for plant growth from a relatively large volume of water. Also collect certain human-made chemicals, such as some persistent pesticides  Biologically accumulate (bioaccumulate) become concentrated at levels that are much higher in the living cells than in the open water.  especially true for persistent chemicals - substances that do not break down readily in the environment - like DDT and PCBs  Small fish and zooplankton eat phytoplankton toxic chemicals accumulated by phytoplankton are concentrated in animals that eat them  Increasing concentration through the food chain is known as biomagnification.  Top predators (lake trout, salmon, gulls) may accumulate concentrations high enough to cause serious deformities or death  Concentration in the fatty tissues of top predators can be millions of times higher than concentration in water  Eggs of aquatic birds often have some of the highest concentrations of toxic chemicals Habitat and biodiversity  Nearly all of the existing forests have been cut at least once and the forest and prairie soils suited to agriculture have been plowed or intensively grazed  Construction of dams and urbanization  Streams have been changed by physical disturbance, sedimentation, changes in runoff rates due to changing land use, and increases in temperature caused by removal of vegetation.  70 - 80 % of the original wetlands of Southern Ontario have been lost since European settlement  U.S. loss of wetlands  42% in Minnesota – 92% in Ohio  Loss of these lands  problems for hydrological processes and water quality because of the natural storage and cleansing functions of wetlands  Biodiversity  # of species and the genetic diversity within species  Some species have become extinct as a result of changes in basin and many threatened with extinction or loss of important genetic diversity  Lack of diversity within a species can also increase the vulnerability of the population to catastrophic loss caused by disease or a major change in environmental conditions. Exotic Species  Introduction of exotic, i.e., non-native, species of plants and animals.  Sea lamprey, carp, smelt, alewife, Pacific salmon and zebra mussels  impacts.  Invading plants such as purple loosestrife and European buckthorn displace native species  Changes in terrestrial plant communities have been caused by suppression of fire  Invasion by exotic species has resulted in loss of biodiversity Fish Consumption Advisories  1971  the first sport fish advisory was issued in the Great Lakes for people consuming fish caught from the lakes  Issued on a regular basis to limit exposure and protect health  Strictest for women of childbearing age, pregnant women and pre-teen children  Trimming visible fat and broiling rather than frying so that fat drips away will reduce a large proportion of these contaminants in fish Sustainable Development  Pollution prevention, protecting and restoring habitat, protecting biodiversity, understanding the ecosystem and cleaning up old pollution problems  The process of change in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are made consistent with future as well as present needs  World Commission on Environment and Development (Bruntland Commission)  Test of whether sustainable development has been achieved will be whether this integrity has been restored or maintained  Integrity of an ecosystem  ecosystems contain mechanisms that create both stability and resiliency within them  capacity of the system to remain intact, to self-regulate and evolve Geographic Areas of Concern  Areas of Concern  are those geographic areas where beneficial use of water or biota is adversely affected or where environmental criteria are exceeded to the extent that use impairment exists or is likely to exist  Most IJC Areas of Concern are near the mouths of tributaries where cities and industries are located.  Several of the areas are along the connecting channels between the lakes.  Long-term accumulation of contaminants deposited from local point and nonpoint sources and from upstream sources  Nearly all the Areas of Concern have contaminated sediments.  Continued remedial and preventive action is necessary.  Remedial Action Plans (RAPs) to guide specific rehabilitation activities in all 42 areas (one Area of Concern - Collingwood Harbour - has been cleaned up) Major Diversion Proposals  Large-scale diversion of water from water-rich regions of North America to water-poor areas experiencing growth in population and industry  Interbasin transfer of Great Lakes water or Canada's Arctic fresh waters southward to the western U.S.  1960s, a California engineering firm proposed a 'North American Water and Power Alliance' (NAWAPA). The plan included diversion of water from Alaska and northwestern Canada through a major valley in the Canadian Rockies (Rocky Mountain Trench) for distribution as far as Mexico  Colorado proposal called for a canal or a pipeline to carry water from the Great Lakes to rapidly growing economies in the Southwest. Both ideas were opposed by all Great Lakes states and the Province of Ontario.  Great Recycling and Northern Development (GRAND) Canal concept was revived in l985 after being proposed in the l950s. The plan calls for turning James Bay into a freshwater lake using a dam to prevent mixing with saltwater from Hudson Bay. Fresh water would then be pumped over the Arctic divide and transferred into the Great Lakes. Great Lakes water would in turn be diverted for sale to western states. Development would require an estimated $l00 billion
More Less

Related notes for Geography 2011A/B

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.