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Lecture 11

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University of Toronto Scarborough
Environmental Science

 Geoscience is all about protecting human society from natural hazards. For mega cities you need to look at energy requirements and waste management. An urban shadow is the economic impact a city has. Toronto needs concrete, so we look for good quality rocks.  We don’t use surface water because there polluted and very sensitive to contamination. Groundwater that moves down through rocks and sediments (between the fractures which becomes passageways) use geological techniques to see the 3-d shape of the groundwater movement (drilling etc.)  Urban development causes rivers to harden, meandering river with big bends at first, but with urbanization water just flushes from hard surfaces and less going into the ground. Discharge of water becomes flashier, erosion problems and flooding. River wants to straighten itself.  Waste, lots of different sources of waste are put in landfills, classically out of sind out of mind, gravel pit for municipal waste, these landfills are like teabags, cuz when it rains it becomes a leechate, which then turns into plumes at the bottom. Modern landfills need to have thick plastic clay layers and pipes to collect the lechate. But many old land fills, about 1200 of them, we need to remediate them.  Cities like to develop greenfields but its not good cause you contaminate the ground underneath and cause problems for the future. What it becomes is brownfield. Biological agents are used to clean these up.  Horse manure was the magical material that cleaned up gases from soil. Radon gas is the product of the breakout of uranium. Breaks down into things like polonium solids. Its an emergin problem because people inhale it and get lung cancer. Geology is bad in terms of radon hazards from granite and shale breakdown.  1998 was the warmest year, and its been fairly stable since. Maybe cooling in the future.  Biggest mining quarry in Canada is Alberta for oil sands.  Scope of environmental Geoscience- see slide.  We do not know a lot about our own environment.  U.S experiences greatest costs from natural disasters, bigger area, more cities. Underscores how urban areas are more susceptible to disasters. So as urban areas get bigger, danger goes up. We are less protected and more susceptible to natural hazards. More people live in cities then rural areas. 80% of canadians live in urban areas.  Anthropocene, the epoch of man began with the invention of the steam engine, the industrial revolution, big demand for resources, factories, movement of people from poor paying jobs. URBANIZATION is the number one environmental issue because a lot of things stem from it.  A built landscape is whats on top of the original landscape. There is a rapid hardening of water sheds. Replacing what was permeable surfaces like soil and grass to impermeable surfaces like concrete and asphalt.  Blue arrows is surface run off, red arrows are base flow, basic ground water. Ground water later emerges as springs. Tiny springs keep rivers flowing in summer when there is no rainfall. Surface flow increases, base flow is small and much reduced.  A hydrograph shows the amount of water coming down a river through time. Once you start urbanizing the water sheds, ur writing off the creeks.  A microburst happened in Steeles avenue, august 2005. Trees intercept a lot of rainfall. Urbanizing compounds this problem.  The red area called the Mackenzie valley (the interior of the country), which is warmest, water bodies like oceans moderate temperature, they reduce extremes in climate, middle of Canada gets coldest winter and hottest summers. Huge north areas are covered in permafrost which is ground that remains frozen throughout the whole year. This thaws down in the summer (the active layer), you can go down several hundred metres and the rock and the soil would still be frozen. When you thaw frozen ground, you get subsidence, land surface actually goes down. Stable when built on frozen ground, then settling when thawed.  The beafort sea is where a lot of canada’s oil and gas is found. You need to transport it through pipes but you have to find a way to keep these pipes warm which is a problem. As you go south you can discontinous permafrost.  What caused the hypsithermal warming event? Astronomical variables (the greatest warmth in the last 10k years)  Toktoyatok, sea is invading, land is subsiding.  Southern Alberta has the heaviest use of surface water, need water to get oil out of tarsands (6 barrels of water for 1 barrel of oil), 2. Southern Alberta is really dry and has very little waterfall, so you need it for crops/irrigation.  Walkerton, Ontario is the southwest part of the province, had a municipal well, pulled groundwater out to feed the whole community. You get a cone of depression that pulls things down into the well. Manure got into the well and killed people.  Bathtub effect, you fill up the landfills with groundwater and make lechate, chloride isopleths are contours of chloride content in groundwater. It reaches at least 700m from the land fill. You need to put a liner to stop this these days. Millions of dollars to investigate just one landfill. Pipes are put in to collect leechate and methane gas which can be used later.  Areas of concern, places that are so contaminated you need immediate action, ABOUT 40 places, harbors are sites of contamination because thers lots of industrial activity. They are enclosed water bodies, limited flushing, they concentrate contaminants. This triggers a r.a.p (remedial action plan) which are really expensive, getting community and scientist together to see what to do about the problem. If the contaminants are dealt with there taken off the list. Collingwood harbour is the only site that was cleaned up. Hamilton harbour was the scene of a major rap.  Only one site has been delisted and its colingburg harbour  Hamilton harbour-scene of major rap  100 km away-harbour-port hope o Uranium refinery..low level waste been dumped there o Waste putin Proper line landfill  Malvern famous because when subdivision were put in there 25 yrs ago, builton top of radium dump,houses had rto be closed down, soils treated..  Historicwaste ...comes back to bite us when we waste revines and stuff  Historic waste used to reclaim land..huge areas of torontos waterfront..historic fill/waste dumpedin lake to make new land  Everything south of front street is reclaimed land made of fill o Used to be where beach was  Harbour land filling -brown all fill.. o Red area, used to be major bay at mouth of don river(ash bridges bay)..sewage was th dumped in there..19 century..brewing industry, grain used to feed pigs...waste
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