Chapter 11 Water Resources & Water Pollution. Water Hydrogen bonding – strong attractive forces...
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Transcript of Chapter 11 Water Resources & Water Pollution. Water Hydrogen bonding – strong attractive forces...
Chapter 11
Water Resources
&
Water Pollution
Water
• Hydrogen bonding – strong attractive forces• Water expands when it freezes• Liquid phase is 0ºC (32ºF) to 100ºC (212ºF)• High heat capacity (4.184 J/g-ºC)• Excellent solvent – dissolves many cmpds• Self ionization of water• Filters UV in aquatic systems• High surface tension• High wetting ability
Water Supports All Life
• Poorly managed resource– We waste it– We pollute it
• Availability– 97.4% is salt water– 2.6% is usable for fresh water
• Usable water
Usable Fresh Water
• The 2.6% is the following:– Polar caps– Deep ground water (gw)– Usable fresh water is:
• Ground water • Water vapor• Streams & lakes
• World supply of water– Equated to 26 gal total:2.5 teaspoons for us
• Hydrologic Cycle
Global Warming
• Global warming can increase the rate of evaporation– Shift precipitation patterns– Disrupt water supplies– Disrupt food supplies– River & stream flow rates may change
Types of Water Resources
• Surface water – does not penetrate the ground – Runs off to bodies of water– Evaporates into the atmosphere
• Ground water – percolates through the soil and rocks– Zones of saturation
Ground Water
• Zones of Saturation– Water table is the top– Aquifers lie along the bedrock
• Naturally recharge
• Fluctuates by elevation & pressure
• Flow depends on the level of the water table, stream elevation, etc
Human Influence
• Data from 2002– During the last century, the population increased 3X
while the water consumption increased 7X
– Use 55% of the available water
– For over 500 million people, water is scarce
• Projected for 2025– Use will increase to 70% of available water
– 2.4-3.4 billion people, water will be scarce
Annual Precipitation
• 41cm or less/year– Western US
• 41-81cm/year– Middle US states
• 81-122cm/year– Northeastern US
• 122cm or more/year– Southeastern states– West costal land
• Much of the US experience water shortages
Fresh Water Supply
• Dams and reservoirs stop runoffs
• Reroute surface water to more needed areas
• Withdraw gw from depths
• Desalinate water to remove salt
• Reduce waste
• Reclaim fresh water
Desalination
• Processes– Distillation – boiling off water & purifying it– Reverse osmosis – forcing it through a
membrane to remove the salt
• Disadvantages– Expensive– Produces large amounts of waste salts
• Example - web
Flooding
• Heavy rain & snow melts
• Floodplains – productive wetlands– Fertile soil– Ample water– Suitable water recreation
• Recharge the ground water
Reduce Flooding
• Channelization– Straighten streams– Deepen stream beds– Increase stream flow, you increase erosion
• Build levees– Contain and speed up flow
• Build dams– Contain water in reserves
• Identify and manage flood prone areas
Sources of Water Pollution
• Change in water quality– Infectious agents
– Oxygen demanding waste
– Inorganic chemicals
– Organic chemicals
– Excess plant nutrients
– Sediments
– Radioactive materials
– Heat (thermal pollution)
Water Quality
• Coli form bacteria– WHO 0/100ml drinking water– EPA 200 colonies/100 ml swimming water
• Dissolved oxygen
• Biological oxygen demand - BOD
• Chemical analysis – chemical pollutants
• Indicator species – reveal certain pollutants
Sources of Water Pollution
• Point Source – can identify the source of the pollution– For example – a water or sewer pipe
• Non-point Source – can not be traced to any one particular site– For example – agricultural runoff (which
farm?)
Safe Drinking Water
• 1970 – 30% of developed countries had safe drinking water
• 2000 – 72% had safe drinking water
• Still 1.4 billion people world wide that do not have safe drinking water
• Cost would be $23 billion/year for 8-10 years to provide safe drinking water for all
Pollution of Fresh Water
• Flowing streams can recover fast– US Stream Data– Large amount of aquatic species die– Hudson River clean-up– Burning of Cuyahoga River (1959 & ‘69)
• Lakes flow less and contain stratified layers– Pollution remains longer– Settles in the benthic layer in a concentration of
pollutants– Eaten by organisms that are part of the food web
Cultural Eutrophication (CE)
• Nutrient rich inputs into a lake• Nutrients added by humans (nitrates &
phosphates)• Hot weather promotes dense growth of
weeds• Decomposition of weed produce excess
nutrients• Anaerobic bacteria take over
Preventing CE
• Waste water treatment
• Ban or limit the use of phosphate soaps
• Soil conservation
• Clean-up– Mechanically remove weeds– Control weeds by herbicides & algaecides– Introduce oxygen into the water
Groundwater Pollution
• Principle water supply• Can not recover• One or more organic chemical pollutants
are found in 45% of municipal water supplies
• Out of 26,000 industrial waste pond & lagoons, 1/3 are not lined to prevent toxic liquid waste from entering the groundwater
Ocean Pollution
• Off shore dumping– Dredge spoils– Sewage sludge – toxic mixture of chemicals and
infectious agents
• Coastal areas input waste directly and many are untreated
• Beach pollution• Shellfish contamination• Human viruses from raw sewage• Crude oil & refined petroleum spills
Oil Spill Clean-up• Mechanical methods
– Vacuum– Floating booms– Absorbent agents
• Chemical methods– Coagulating agents– Dispersing agents– Fire
• Physical methods– Natural wave action
• Biological methods – Bacteria
Clean Water Acts
• 1972 – Federal Water Pollution Act• 1977 – Clean Water Act• 1987 – Water Quality Act• All set standards
– Allowable levels of key pollutants– Requires polluters to have permits– Discharge trade policy (buy credits from permit
holders)
Point Source
• Water Treatment Technologies– Primary – screens debris and allows solids to
settle– Secondary – biological process (aerobic
bacteria degrade 90%– Port Labelle www.southerndatastream.com
Slides for NSF Research Trip
• Miller Brewing Company in Fulton, NY had an underground chemical tank rupture.– The next slide is a picture of the abatement
tower that allowed the water to pass over a column of resin beads to remove the contaminated VOC’s.
– The aquifer under the Miller plant contaminated the water supply for villages surrounding the area
Miller Brewing Company
Oswego City Harbor
• Core samples were taken from the Oswego Harbor looking for lead, zinc and other metals in the sediment. – The next 2 slides show the sampling of the
sediment in the harbor
Core Sample – Lake Ontario
Core Sample – Lake Ontario