Review Day 2

Human Diet

Math Problem• If an average refrigerator uses 500 watts of energy per hour on a daily

basis, and your energy cost is $0.11 per kwh, approximately how much does the energy used by the refrigerator cost per month? • a. $1.30 • b. $13 • c. $40 • d. $55 • e. $132

Long Division... Last time.• 10/5• 176/160• 1305/30

Water ReviewWater Pollution

WATER POLLUTION: SOURCES, TYPES, AND EFFECTS•Water pollution is any chemical, biological, or

physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses.• Point source: specific location (drain pipes,

ditches, sewer lines).• Nonpoint source: cannot be traced to a single

site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)

Major Water Pollutants and Their Effects

Major Water Pollutants and Their Effects

• Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C.• Only a few fish species can survive in water less than 4ppm at

20°C.

POLLUTION OF FRESHWATER STREAMS• Most developed countries have sharply reduced point-

source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.• Stream pollution from discharges of untreated sewage

and industrial wastes is a major problem in developing countries.

Cultural Eutrophication• Eutrophication: the natural nutrient enrichment of a shallow lake,

estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land.• Cultural eutrophication: human activities accelerate the input of

plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake.• 85% of large lakes near major population centers in the U.S. have some

degree of cultural eutrophication.

Coal strip mine runoff

Polluted air

Deicing road salt

Pesticidesand fertilizers

Hazardous waste

injection well

Pumping well

Gasoline station

Water pumping well

LandfillSewer

Buried gasoline and solvent tanks

Cesspool, septic tank

Groundwater flow

Confined aquifer

Confined freshwater aquifer

Unconfined freshwater aquifer

Accidentalspills

Waste lagoonLeakage from faulty casing

Discharge

POLLUTION OF GROUNDWATER• It can take hundreds to thousand of years for contaminated

groundwater to cleanse itself of degradable wastes.• Nondegradable wastes (toxic lead, arsenic, flouride) are

there permanently.• Slowly degradable wastes (such as DDT) are there for

decades.

Aquifer

Water well

Migrating vapor phase

Contaminant plume moveswith the groundwater

Free gasolinedissolves ingroundwater(dissolved phase)

Groundwaterflow

Watertable

Gasolineleakage plume(liquid phase)

Leakingtank

Bedrock

Solutions

Groundwater Pollution

CleanupPrevention

Find substitutes for toxic chemicals

Install monitoring wells near landfills and underground tanks

Require leak detectors on underground tanks

Ban hazardous waste disposal in landfills and injection wells

Store harmful liquids in aboveground tanks with leak detection and collection systems

Pump to surface, clean, and return to aquifer (very expensive)

Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed)

Keep toxic chemicals out of the environment

Inject microorganisms to clean up contamination (less expensive but still costly)

Fig. 21-10, p. 505

Healthy zoneClear, oxygen-richwaters promote growthof plankton and sea grasses,and support fish.

Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses, useup oxygen, and degrade habitat.

Red tidesExcess nitrogen causesexplosive growth of toxicmicroscopic algae,poisoning fish andmarine mammals.

FarmsRunoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Toxic sedimentsChemicals and toxic metals contaminate shellfish beds, kill spawning fish, andaccumulate in the tissues of bottom feeders.

Construction sitesSediments are washed intowaterways, choking fish and plants, clouding waters, and blocking sunlight.

Urban sprawlBacteria and viruses fromsewers and septic tanks contaminate shellfish beds

Oxygen-depletedzone

Closedbeach

CitiesToxic metals and oil from streets and parking lots pollute waters;

IndustryNitrogen oxidesfrom autos andsmokestacks,toxic chemicals,and heavy metals in effluents flow into bays and estuaries.

Closedshellfish beds

OCEAN POLLUTION

• Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff.

Reduce input of toxic pollutants

SolutionsCoastal Water Pollution

Prevention Cleanup

Use wetlands, solar-aquatic, or other methods to treat sewage

Require at least secondary treatment of coastal sewage

Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful by-products(still under development)

Improve oil-spill cleanup capabilities

Recycle used oil

Regulate coastal development

Protect sensitive areas from development, oil drilling, and oil shipping

Ban ocean dumping of sludge and hazardous dredged material

Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters

Separate sewage and storm lines

Require double hulls for oil tankers

Reducing Water Pollution through Sewage Treatment• Raw sewage reaching a municipal sewage treatment

plant typically undergoes:• Primary sewage treatment: a physical process that uses

screens and a grit tank to remove large floating objects and allows settling.• Secondary sewage treatment: a biological process in which

aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes.

Reducing Water Pollution through Sewage Treatment

• Primary and Secondary sewage treatment.

• Prevent groundwater contamination

Solutions

Water Pollution

• Reduce birth rates

• Reduce poverty

• Reduce air pollution

• Practice four R's of resource use (refuse, reduce, recycle, reuse)

• Work with nature to treat sewage

• Find substitutes for toxic pollutants

• Reuse treated wastewater for irrigation

• Reduce nonpoint runoff

Environmental Organizations and Industries• http://webecoist.momtastic.com/2008/09/24/25-environmental-

agencies-and-organizations/