Chapter 11 Water Resources & Water Pollution. Water Hydrogen bonding – strong attractive forces Water expands when it freezes Liquid phase is 0ºC (32ºF)

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