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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 infiltra@on or evapora@on 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 direc@on. •  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 affec@ng 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 dura@on of precipita@on •  Vegeta@on: This intercepts rainfall, uses soil water for transpira@on 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 conduc@vity •  Hydraulic conduc@vity for most material are listed in the table and can vary anywhere between cm to meters per day. Gravel is the best “conduc@ng” 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 con@nuously inundated by water •  Bogs – wetlands that accumulate peat deposits •  Important environmental func@ons –  In coastal loca@ons act as a buffer for storms and high waves –  Natural filters – trap sediment nutrients and pollutants –  Dampen impacts of floods –  Produc@ve land with nutrients –  Recharge loca@ons to aquifers Visit the Congaree!! Summary •  •  •  •  •  Global water cycle Drainage basin and divide Defini@ons of groundwater aquifers Mining of groundwater and shortages Wetlands and their impact Water pollu@on •  It is defined as the degrada@on 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 resul@ng in algal blooms that cut off sunlight and oxygen to the aqua@c animals. In addi@on seaweed can accumulate on beaches •  Oil: Example Exxon Valdez Toxic Substances •  Hazardous chemicals: e.g. MTBE an addi@ve 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 deposi@on in waters have resulted in magnifica@on in the food chain of fish and side effects •  Sediment: Reduces quality of water resources •  Thermal pollu@on: Hot water holds less oxygen hence discharge from power plants could kill aqua@c animals Groundwater pollu@on is very dangerous as ½ of our popula@on 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 par@cles •  Secondary Pumped oxygen helps bacteria in breaking down contaminants •  Advanced Removal of nutrients and heavy minerals •  Sludge Disposal to regions for soil conserva@on or strip mines for reclama@on Summary •  •  •  •  Surface water point and non ­point sources Water quality standards Various forms of pollu@on 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 •  Si@ng problems for a landfill or incenerator include, site suitability factors such as geographic, geologic and hydrologic environment •  Social and economic jus@ce are emerging fields as these sites are near people who are ethnic minority or lower economic status •  Waste disposal is a $20 billion industry Introduc@on (contd) •  Earlier philosophy was dilute and disperse, which worked as the popula@on 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 prac@ced The amount of urban waste has reduced from 90% to 65% (1980 ­present) As the popula@on 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 produc@on… –  Eliminate subsidies for @mber, minerals, oil –  Green buildings using recycled materials for construc@on –  Financial penal@es for non ­compliance of materials management and vice ­versa –  Incen@ves 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 •  Compos@ng –  Biochemical process resul@ng in organic macer called compost used in agriculture [not used in US] •  Incinera@on –  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. •  Poten@al hazards include leachate mineralized liquid with bacteria may enter the groundwater system. •  Escape of methane gas which is a by ­product of the decomposi@on Site selec@on for landfills •  Topographic relief –  Best sites are top of the hills –  Favorable for deep GW table –  Areas of low precipita@on –  Example the two figures on the previous page –  No thru flow of water •  Loca@on of groundwater •  Amount of precipita@on •  Type of soil and rock •  Rela@onship to water flow Secure landfill has a leak detec@on and landfill monitoring system Liners of plas@cs and clay Other methods include land applica@ons of biodegradable material; Surface impoundments including aera@on pits and deep well disposal Incinera@on 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 par@culates and acid forming components Suitable Condi@ons for Burial 1.  2.  3.  4.  5.  6.  7.  8.  9.  10.  11.  Low rainfall Deep water table Modest soil hydraulic conduc@vity Slow moving groundwater High adsorp@on and ion exchange rates Homogeneous geology Low erosion in area Absence of exploitable resources Absence of surface water Low probability of volcanic or earthquake ac@vity Adequate buffer zone Disposal in Geologic Environment Geologic disposal development objec@ves •  Iden@fy sites with tectonic stability and slow moving groundwater •  Determine current and future geologic and hydrologic characteris@cs •  Evalua@on of risks associated with geologic change and are they acceptable to poli@cal 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, pes@cide 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 reproduc@vity of marine organisms •  Reduc@on of dissolved oxygen •  Algal blooms from nutrient rich waste resul@ng in oxygen deple@on •  Change in specific marine habitats or major changes of marine ecosystems Summary •  Integrated Waste Management •  Solid waste disposal •  Sanitary landfills, problems and site selec@on and monitoring •  Hazardous waste management •  Responsible management and alterna@ves to disposal Chapter 13 The Geological Aspects of Environmental Health Introduc@on •  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 pes@cides 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 Infec@ous Diseases Food, water, air and soil. Examples are Legionnaires, Salmonella, malaria etc. •  Cultural factors such as local customs and industrializa@on; 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 quan@@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 •  Accumula@on is the process that causes increase in reten@on in the soil •  Deposi@on Trace elements and health •  Every element has a broad spectrum of possible effects, large quan@@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 popula@on experiences the response or maybe even lethal Imbalances •  Fluorine •  Iodine young bones helps prevent tooth decay, forma@on 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 •  Radioac@vity and Radon gas 14 Mineral Resources Minerals and Human use •  There are many minerals used by humans everyday… we some@mes take these for granted •  Dishes we eat from..telephone used for conversa@on 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 conserva@on 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 [poten@ally extractable at a profit] •  A reserve is that por@on of a resource that is iden@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 produc@on –  Building aggregates –  Chemical industry –  Agriculture Limited Availability •  The possible responses to limited availability are: –  Find more sources –  Find a subs@tute –  Recycle exis@ng minerals –  Be efficient in use –  Acempt to work without them Limited Availability [contd.] •  There are three possible ways for use (and consequent deple@on of the exis@ng 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 forma@on 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 contamina@on Other impacts •  Water pollu@on: Drainage from mines containing harmful products such as cadmium, lead etc. can pollute water, making it unfit for use •  Air pollu@on: Smel@ng 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 pollu@on but are necessary to accommodate workers and families Minimizing environmental impact •  Environmental regula@on: Clean air and water acts are examples of acempts at regula@on •  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 conserva@on Summary •  •  •  •  •  Use if mineral resources in daily life Defini@ons, resources, reserves Limited availability Mineral genesis Environmental impacts and mimimizing techniques ...
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This note was uploaded on 02/10/2011 for the course GEOL 103 taught by Professor Lakshmi during the Spring '10 term at South Carolina.

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