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Unformatted text preview: The Hydrological Cycle is what keeps water moving and us alive! The global water cycle •  Water reaches the surface as rainfall or snow. It leaves the surface by infi[email protected] or [email protected] and some of it runs off to the oceans. •  The amount of water going into the ocean by way of runoff from the land surface (with sand/gravel and chemicals) equals that transported by the atmosphere in the opposite [email protected] •  The table shows that the amount of water that actually serves humanity is less than 1% of the total available water Surface Runoff and Sediment •  Water that runs off the land surface carries with it sediment that is dislodged from the surface. •  Watershed or drainage basin is an area which drains water to the outlet. The drainage divide is a line where a drop of water falling on either side could end up very far apart. •  Large drainage basins are always broken up into smaller sub ­basins, e.g. the Mississippi River basin consists of the Missouri and Ohio basins Factors aff[email protected] sediment yield •  Geology: Clay over shale allows lesser amount of water to infiltrate as compared to sandy soils on sandstone. •  Topography: The larger the difference between the highest and lowest point in the basin, the greater is the velocity of the river •  Climate: Type, intensity and [email protected] of [email protected] •  [email protected]: This intercepts rainfall, uses soil water for [email protected] and its roots hold the soil and prevent erosion •  Land use: Agriculture adds lots of runoff and sediment whereas urbanized areas add lot of runoff to the system Aquifers •  Earth material capable of storing and moving water are called aquifers. Examples are gravels, sandstone, fractured rocks, granites etc. •  A confining layer does not allow for easy movement of water (clay) •  An unconfined aquifer has a water table surface •  A confined aquifer is layered by confining layers on both sides •  A perched aquifers in a pool of water atop a confining layer Aquifers (contd.) •  The recharge of the groundwater occurs in recharge areas. The confined aquifers are under pressure and water can rise in them to the recharge zone (artesian wells). •  Recharge is adding and discharge is removing water from an aquifer. •  A spring forms when water flowing in an aquifer intersects the ground surface •  When water is pumped out from an aquifer the water table drops in the vicinity of the well resulBng in a cone of depression. In addiBon, withdrawal of water from deeper locaBons consumes more energy and possibly had more dissolved minerals Groundwater movement •  The water moves in the aquifer along the hydraulic gradient (almost equivalent to the slope of the water table). This movement is governed by Darcy’s law whose two factors are hydraulic gradient and hydraulic [email protected] •  Hydraulic [email protected] for most material are listed in the table and can vary anywhere between cm to meters per day. Gravel is the best “[email protected]” material even though clay has a high porosity, it holds the water @ghter due to its numerous small pores as opposed to gravel’s large pore spaces Groundwater supply •  Within 800m of the land surface, the total flow in the Mississippi over the last 200 years is the amount of water stored •  Groundwater “mining” or serious over ­ withdrawals is a problem in many regions, in some areas discharge is 20 @mes recharge which will most definitely result in deficit Wetlands •  Swamps and marshes– frequently or [email protected] inundated by water •  Bogs – wetlands that accumulate peat deposits •  Important environmental [email protected] –  In coastal [email protected] act as a buffer for storms and high waves –  Natural filters – trap sediment nutrients and pollutants –  Dampen impacts of floods –  [email protected] land with nutrients –  Recharge [email protected] to aquifers Visit the Congaree!! Summary •  •  •  •  •  Global water cycle Drainage basin and divide Defi[email protected] of groundwater aquifers Mining of groundwater and shortages Wetlands and their impact Water [email protected] •  It is defined as the [email protected] of the quality of water by biological, physical or chemical criteria •  A pollutant is a substance whose excess causes harmful effects to living organisms Selected pollutants •  Oxygen demanding bacteria: Bacteria that feed on organic macer and require oxygen for survival reduce the amount of oxygen. A high biochemical oxygen demand (BOD) indicates high amount of decaying organic macer •  Pathogenic Organisms: There are numerous pathogenic microbes but the most important is fecal coliform bacteria specifically e ­coli that are harmful. Numerous outbreaks that went undetected (so people could boil water) are lethal •  Nutrients such as nitrogen and phosphorus help “feed” algae [email protected] in algal blooms that cut off sunlight and oxygen to the [email protected] animals. In [email protected] seaweed can accumulate on beaches •  Oil: Example Exxon Valdez Toxic Substances •  Hazardous chemicals: e.g. MTBE an [email protected] to gasoline designed to reduce carbon monoxide emissions finds its way to ground water and may be carcinogenic •  Heavy metals: e.g. lead, cadmium, zinc and mercury. Mercury [email protected] in waters have resulted in magnifi[email protected] in the food chain of fish and side effects •  Sediment: Reduces quality of water resources •  Thermal [email protected]: Hot water holds less oxygen hence discharge from power plants could kill [email protected] animals Groundwater [email protected] is very dangerous as ½ of our [email protected] Depends on this as a water source NAWQA: Assessment of water quality is an important program of USGS Salt water intrusion occurs when excessive pumping occurs near the coast and the cone of ascension of the saline water intersects the well Two contaminants that Are dangerous Coliform bacteria and Nitrates Wastewater treatment •  Primary Includes the removal of larger [email protected] •  Secondary Pumped oxygen helps bacteria in breaking down contaminants •  Advanced Removal of nutrients and heavy minerals •  Sludge Disposal to regions for soil [email protected] or strip mines for [email protected] Summary •  •  •  •  Surface water point and non ­point sources Water quality standards Various forms of [email protected] Case studies WASTE MANAGEMENT: WASTE AS A RESOURCE Concept of waste management •  Landfills are running out of space and the costs are rising rapidly for disposal of waste •  [email protected] problems for a landfill or incenerator include, site suitability factors such as geographic, geologic and hydrologic environment •  Social and economic [email protected] are emerging fields as these sites are near people who are ethnic minority or lower economic status •  Waste disposal is a $20 billion industry [email protected] (contd) •  Earlier philosophy was dilute and disperse, which worked as the [email protected] and hence the waste were both low •  The new philosophy is REDUCE, RECYCLE and REUSE tenets of Integrated Waste Management (IWM) •  Recycling can reduce weight of urban waste by 50% and should be [email protected] The amount of urban waste has reduced from 90% to 65% (1980 ­present) As the [email protected] increases, even recycling will not be able to keep abreast of waste produced. The new concept is materials management Materials management •  With a goal of zero waste [email protected]… –  Eliminate subsidies for @mber, minerals, oil –  Green buildings using recycled materials for [email protected] –  Financial [email protected] for non ­compliance of materials management and vice ­versa –  [email protected] in jobs for materials management Disposal Methods •  On ­Site Disposal –  Flushing of the waste into the sewer system which ends in the sewage treatment plant •  [email protected] –  Biochemical process [email protected] in organic macer called compost used in agriculture [not used in US] •  [email protected] –  Burn waste at high (1000C) temperature. Results in ash which can be disposed in landfill but results in nitrogen and sulfur dioxide emissions/acid rain •  Open Dumps –  Oldest, commonest and most un ­hygenic method Sanitary landfill •  Buried in the ground under a specially designed tarp. •  [email protected] hazards include leachate mineralized liquid with bacteria may enter the groundwater system. •  Escape of methane gas which is a by ­product of the [email protected] Site [email protected] for landfills •  Topographic relief –  Best sites are top of the hills –  Favorable for deep GW table –  Areas of low [email protected] –  Example the two figures on the previous page –  No thru flow of water •  [email protected] of groundwater •  Amount of [email protected] •  Type of soil and rock •  [email protected] to water flow Secure landfill has a leak [email protected] and landfill monitoring system Liners of [email protected] and clay Other methods include land [email protected] of biodegradable material; Surface impoundments including [email protected] pits and deep well disposal [email protected] of waste; the material is burned and the ash is collected In a water chamber. Carbon dioxide, water and air is emiced from The smokestack. There are various parts of this system including a Scrubber which eliminates the [email protected] and acid forming components Suitable [email protected] for Burial 1.  2.  3.  4.  5.  6.  7.  8.  9.  10.  11.  Low rainfall Deep water table Modest soil hydraulic [email protected] Slow moving groundwater High [email protected] and ion exchange rates Homogeneous geology Low erosion in area Absence of exploitable resources Absence of surface water Low probability of volcanic or earthquake [email protected] Adequate buffer zone Disposal in Geologic Environment Geologic disposal development [email protected] •  [email protected] sites with tectonic stability and slow moving groundwater •  Determine current and future geologic and hydrologic [email protected] •  [email protected] of risks associated with geologic change and are they acceptable to [email protected] and societal standards Ocean Dumping Types of waste dumped into the oceans (U.S.) •  Dredge spoils – sand, silt, clay, rock and other industrial sediment •  Industrial wastes – acids, paper mill wastes, [email protected] wastes, sewage waste •  ConstrucBon and demoliBon debris – plaster, cinder blocks, stone, @le… •  Solid waste – refuse, garbage, explosives •  RadioacBve waste Impacts of Ocean Dumping •  Killing or retarding growth and [email protected] of marine organisms •  [email protected] of dissolved oxygen •  Algal blooms from nutrient rich waste [email protected] in oxygen [email protected] •  Change in specific marine habitats or major changes of marine ecosystems Summary •  Integrated Waste Management •  Solid waste disposal •  Sanitary landfills, problems and site [email protected] and monitoring •  Hazardous waste management •  Responsible management and [email protected] to disposal Chapter 13 The Geological Aspects of Environmental Health [email protected] •  Industrial and agricultural processes use many materials that are of benefit to society BUT they may also have adverse environmental consequences to people and ecosystems world wide •  Herbicides and [email protected] have protected our crops but has adverse consequences •  Example: DDT to combat malaria can travel up the food chain •  Disease is the imbalance resul0ng from a poor adjustment between an individual and the environment •  Environmentally Transmiced [email protected] Diseases Food, water, air and soil. Examples are Legionnaires, Salmonella, malaria etc. •  Cultural factors such as local customs and [email protected]; e.g. polished rice eaten by Japanese has trace amounts of asbestos which can cause cancer! •  Climate factors – humid climate can cause malaria Geologic Factors in Human Health •  Elements – Trace elements in a small amount are okay but in larger [email protected]@es may prove unhealthy •  Trace elements may become concentrated in the human body •  Weathering frees trace elements by physical and chemical breakdown of rock material •  Leaching of soils is the natural removal of soluble material from the upper and lower horizons •  [email protected] is the process that causes increase in [email protected] in the soil •  [email protected] Trace elements and health •  Every element has a broad spectrum of possible effects, large [email protected]@es of selenium are toxic •  Does dependency can be represented by the dose ­response curve – below a certain level and above a certain level are harmful •  Toxin TD 50 is the dose at which 50% of the [email protected] experiences the response or maybe even lethal Imbalances •  Fluorine •  Iodine young bones helps prevent tooth decay, [email protected] of lack of iodine causes an enlargement of the thyroid called goiter •  Zinc lack of zinc causes low yields and poor seed development and even crop loss •  Selenium dystrophy lack of selenium may cause muscular Quantities of Radon gas have negative health effects Radon gas enters homes by [1] Gas enters by coming thru basement [2] Groundwater in wells [3] From construction materials Avoid by [1] Ventilation [2] Seal points of entry [3] More venting Summary •  Health issues with excess of certain elements •  [email protected] and Radon gas 14 Mineral Resources Minerals and Human use •  There are many minerals used by humans everyday… we [email protected] take these for granted •  Dishes we eat from..telephone used for [email protected] are just a few examples •  Processed mineral value is about 5% of the US GDP •  Reclaimed minerals account for ¼ of these •  Easy to find minerals have been exploited, so, careful [email protected] and recycling are the best method to preserve these resources Resources and Reserves •  Mineral resources are elements, compounds, minerals or rocks concentrated in a form that can be extracted to obtain a useful commodity [[email protected] extractable at a profit] •  A reserve is that [email protected] of a resource that is [email protected]fied and is currently available to be legally extracted at a profit Availability and Use •  There are some necessary in everyday life [e.g. Salt] and there are some that are for pleasure and beauty [e.g. diamonds] •  The four categories of minerals are –  Metal [email protected] –  Building aggregates –  Chemical industry –  Agriculture Limited Availability •  The possible responses to limited availability are: –  Find more sources –  Find a [email protected] –  Recycle [email protected] minerals –  Be efficient in use –  Acempt to work without them Limited Availability [contd.] •  There are three possible ways for use (and consequent [email protected] of the [email protected] mineral resources). One is to keep on the present path and we run out. Another is to conserve and the third is recycling. Of these recycling will protect our resources the longest •  The US relies on a number of these [table] minerals from foreign sources Mineral Genesis •  Igneous: Diamonds are found in kimberlite. Many ores are associated with hydrothermal deposits, e.g. gold, silver, copper, etc. •  Metamorphic: Contact or regional metamorphism can form metallic or non ­metallic minerals such as asbestos and talc •  Sedimentary: Sand and gravel deposits, evaporite deposits of halite (salt) •  Biological (phosphate), weathering and residual deposits are also sources of mineral [email protected] Environmental Impact •  In US, 0.3% of the total land area is used for mining. •  Approximately 1 ­2 billion tons of waste is produced from mines every year •  Open pit mines like the Bingham Canyon Copper mine in Utah •  Leaching process with use of cyanide results in groundwater [email protected] Other impacts •  Water [email protected]: Drainage from mines containing harmful products such as cadmium, lead etc. can pollute water, making it unfit for use •  Air [email protected]: [email protected] and release of products into the atmosphere results in acid rain •  Biological Impacts: Kills plants and animals and can result in spread of disease •  Social Impacts: Towns, close to mines feel the effect of the [email protected] but are necessary to accommodate workers and families Minimizing environmental impact •  Environmental [email protected]: Clean air and water acts are examples of acempts at [email protected] •  New biotechnology: Use of plants to neutralize acid and treat metals is a new way •  Reduce water; Recycle; Reuse are the three R’s of [email protected] Summary •  •  •  •  •  Use if mineral resources in daily life Defi[email protected], resources, reserves Limited availability Mineral genesis Environmental impacts and mimimizing techniques ...
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