ETM Final Notes

7/29/2019 ETM Final Notes

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Soil: The Foundation for Land Ecosystems28/04/2012 20:40:00

Five golden rules of the tropics Keep soil covered Use minimal or no tillage

Use mulch to provide nutrients to the soil Maximize biomass production Maximize biodiversity

Most soils are hundreds of years old They change very slowly

Soil science is at the heart of agriculture and forestry Soil is classified by profile, structure, and type

Soil texture : relative proportions of each soil type Parent material : mineral material of the soil Soil has its origin in the geological history of an area

Weathering : gradual physical and chemical breakdown of parentmaterial

It may be impossible to tell what the parent material was

Soil separates : small fragments smaller than stones

Sand : particles from 2.0 to 0.063 mm


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Silt : particles range from 0.063 to 0.004 mm Clay : anything finer than 0.004 mm

Gravel, cobbles, boulders: particles larger than sand You can see the individual rock particles in sand

Clay particles become suspended in water Clay is gooey because particles slide around each other on a film

of water

Soil properties are influenced by its texture Larger particles have larger spaces separating them Small particles have more surface area relative to their volume Nutrient ions and water molecules cling to surfaces

These properties profoundly affect soil properties


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Infiltration, nutrient- and water-holding capacity, aeration Workability : the ease with which soil can be cultivated

Clay soils are hard to work with: too sticky or too hard Sandy soils are easy to work with

Horizons : horizontal layers of soil from soil formation

Can be quite distinct Soil profile : a vertical slice through the soil horizons

Reveals the interacting factors in soil formation O horizon : topmost layer of soil

Dead organic matter (detritus) deposited by plants High in organic content Primary source of energy for the soil community

Humus : decomposed dark material at the bottom of the O horizon

A horizon (topsoil) : below the O horizon A mixture of mineral soil and humus Permeated by fine roots Usually dark May be shallow or thick Vital to plant growth Grows an inch or two every hundred years

E horizon : pale-colored layer below the A horizon Eluviation : process of leaching (dissolving) minerals due to

downward movement of water B horizon (subsoil) : below the E horizon

Contains minerals leached from the A and E horizons High in iron, aluminum, calcium, other minerals, clay Reddish or yellow colored from oxidized metals

C horizon : parent mineral material Weathered rock, glacial deposits, volcanic ash


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Reveals geologic process that created the landscape Not affected by biological or chemical processes

Gelisols Soils with permafrost within 2 m of the surface

Histosols Organic soils

Spodosols Acid forest soils with a subsurface accumulation of metal-humus

complexes Andisols


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Soils formed in volcanic ash Oxisols

Intensely weathered soils of tropical and subtropical environments Vertisols

Clayey soils with high shrink/swell capacity Aridisols

CaCO3 containing soils of arid environments with subsurfacehorizon development

Ultisols Strongly leached soils with a subsurface zone of clay accumulation

and 35% base saturation

Inceptisols Soils with weakly developed subsurface horizons

Entisols Soils with little or no morphological development

Fertilizer : nutrients added to replace those that are lost Organic fertilizer : plant or animal wastes or both

Manure, compost (rotted organic material) Leguminous fallow crops (alfalfa, clover) Food crops (lentils, peas)

Inorganic fertilizer : chemical formulations of nutrients Lacks organic matter Much more prone to leaching

Transpiration : water is absorbed by roots and exits as water vaporthrough pores ( stomata ; singular = stoma ) in the leaves

Oxygen enters, and carbon dioxide exits, through stomata Loss of water through stomata can be dramatic

Wilting : a plants response to lack of water


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Conserves water Shuts off photosynthesis by closing stomata Severe or prolonged wilting can kill plants

Infiltration : water soaks into the soil Water runoff is useless to plants and may cause erosion

Water-holding capacity : soils ability to hold water after it infiltrates Poor holding capacity: water percolates below root level Plants must depend on rains or irrigation Sandy soils Evaporative water loss depletes soil of water The O horizon reduces water loss by covering the soil

Aeration Novice gardeners kill plants by overwatering (drowning) Roots must breathe to obtain oxygen for energy Land plants depend on loose, porous soil

Soil aeration : allows diffusion of oxygen into, and carbon dioxide outof, the soil

Overwatering fills air spaces Compaction : packing of the soil

Due to excessive foot or vehicular traffic


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Reduces infiltration and runoff Strongly influenced by soil texture

Relative acidity (pH)

The pH scale runs from 1 to 14 7 is neutral (neither acidic or alkaline)

Different plants are adapted to different pH ranges Most do best with a pH near neutral Many plants do better with acidic or alkaline soils Blueberries do best in acidic soils

Dead leaves, roots, other detritus on and in the soil Support a complex food web Bacteria, fungi, mites, insects, millipedes, spiders, earthworms,

snails, slugs, moles, etc. Millions of bacteria are in a gram of soil

Humus : residue of partly decomposed organic matter In high concentrations at the bottom of the O layer Extraordinary capacity for holding water and nutrients

Composting : fosters decay of organic wastes Is essentially humus


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Animals feeding on detritus also ingest mineral soil particles Castings : earthworm excrement of stable clumps of glued

inorganic particles plus humus Burrowing of animals keeps clumps loose

Soil structure : refers to the arrangement of soil particles Soil texture: refers to the size of soil particles A loose soil structure: best for infiltration, aeration, and workability

Topsoil: clumpy, loose, humus-rich soil Loss of topsoil reduces crop yield by 8590%

Mycorrhizae : a symbiotic relationship between the roots of someplants and certain fungi

Fungi draw nourishment from the roots Fungi penetrate the detritus, absorb nutrients, and pass them to

the plant Nutrients are not lost to leaching

Bacteria add nitrogen to the soil Nematodes : small worms that feed on roots

Detrimental to plants May be controlled by other soil organisms (e.g., fungi)

Mineralization : loss of humus and collapse of topsoil All that remains are the minerals (sand, silt, clay)


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Erosion : the process of soil and humus particles being picked up andcarried away by water and wind

Occurs any time soil is bared and exposed Soil removal may be slow and gradual (e.g., by wind) or dramatic

(e.g., gullies formed by a single storm) Vegetative cover prevents erosion from water

Reducing the energy of raindrops Allowing slow infiltration

Grass is excellent for erosion control Vegetation also slows wind velocity

Splash erosion : begins the process of erosion Raindrops break up the clumpy structure of topsoil Dislodged particles wash between other aggregates Decreases infiltration and aeration

Sheet erosion : the result of decreased infiltration More water runs off, carrying away fine particles

Gully erosion : water converges into rivulets and streams Waters greater volume, velocity, energy remove soil

Once started, erosion can turn into a vicious cycle Less vegetation exposes soil to more erosion

Desertification : a permanent reduction in the productivity of arid,semiarid, and seasonally dry areas (drylands)


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No-till agriculture : a technique allowing continuous cropping whileminimizing erosion

Routinely practiced in the U.S.

After spraying a field with herbicide to kill weeds A planting apparatus cuts a furrow through the mulch Drops seeds and fertilizer Closes the furrow

The waste from the previous crop becomes detritus So the soil is never exposed

Low-till farming uses one pass (not 612) over a field

Contour strip cropping : plowing and cultivating at right angles tocontour slopes

Shelterbelts : protective belts of trees and shrubs planted alongplowed fields

The U.S. Natural Resource Conservation Service (NRCS) Established in response to the Dust Bowl Regional offices provide information to farmers and others

regarding soil and water conservation practices U.S. soil erosion has decreased through conservation

Windbreaks, grassed waterways, vegetation to filter runoff

Irrigation : supplying water to croplands artificially Dramatically increases production


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Is a major contributor to land degradation Flood irrigation : river water flows into canals to flood fields Center-pivot irrigation : water is pumped from a well into a giantpivoting sprinkler

The U.S. Bureau of Reclamation is involved with supplying irrigationwater to the western states

Irrigating 4 million hectares (10 million acres) Worldwide irrigation is huge and is still rising

Salinization : the accumulation of salts in and on the soil Suppresses plant growth

Even the freshest irrigation water has some salt Watering dryland soils dissolves minerals in the soil Evaporation or transpiration leaves salts behind

Salinization is considered a form of desertification

Federal Agricultural Improvement and Reform Act (FAIR)(1996) reduced subsidies and controls

Farmers had greater flexibility over what to plant Declining prices prompted farm aid packages, which maintainedsubsidies and controls 2002 Farm Security and Rural Investment Act subsidized farmproducts and kept price supports and farm income The Food, Conservation and Energy Act of 2008 kept highsubsidies and encouraged farmers to plow grasslands

But it does have programs to conserve soil and wetlands


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The Conservation Reserve Program (CRP; 1985) Farmers are paid $125/hectare ($50/acre) per year Highly erodible land is put into forest or grass In 2008, 14 million hectares (34.7 million acres) were enrolled,

saving 454 million tons of topsoil from erosion/year The 2009 acreage was reduced to 32 million acres

Conservation activities now receive $5 billion/year Wildlife Habitat Incentives Program (WHIP) Environmental Quality Incentives Program (EQIP)

The 2002 Conservation Security Program (CSP) Encourages stewardship of farms, forests, watersheds Renamed the Conservation Stewardship Program in the 2008

farm bill $1 billion to enroll 12 million acres of farmland


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Nuclear Power 28/04/2012 20:40:00

Countries reconsidered nuclear power after the 1986 catastrophicaccident at Chernobyl, in the Soviet Union Other sources of electricity have their own problems

Coal: generates the most greenhouse gases and pollution Oil and natural gas: are limited Oil: vital for transportation Hydroelectric: already heavily developed Wind and solar: provide only a small amount of electricity

The objective of nuclear power: to control the nuclear reaction Energy is released as heat Heat is used to boil water to steam

The steam turns a conventional turbo generator Nuclear plants are base load plants They always operate (except during refueling) They are large (up to 1,400 MW)

Nuclear energy involves changes at the atomic level Fission: a large atom of one element is split into two atoms of

different elements Fusion: two small atoms join to form a larger atom of a different

element The products of both have less mass than the starting material

The small mass is multiplied by the speed of light squared, resultingin a tremendous release of energy


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Fission occurs when a neutron hits the nucleus of 235 U at just the rightspeed

Some atoms of 235 U undergo radioactive decay and release neutrons These neutrons can hit other 235 U atoms, producing highly unstable

236 U 236 U undergoes fission into lighter atoms (fission products)

More neutrons are given off, releasing lots of energy This domino effect causes a chain reaction

A nuclear reactor has a continuous chain reaction But does not amplify it into an explosion Control is through enriching uranium to 35% 235 U

Faster neutrons absorbed by 238 U convert it to 239 Pu Plutonium also undergoes fission and releases energy

Moderators surround the enriched uranium A moderator slows down neutrons to the right speed to trigger

another fission Light-water reactors (LWRs): moderator is near-pure water

Loss of cooling accident (LOCA): occurs when a cracked reactor loses

water The missing moderator would stop fission

The fuel core could still overheat Meltdown: enough energy is released to melt the core


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Molten material falling into remaining water could cause a steamexplosion

Backup cooling systems keep the reactor in water The entire assembly is encased in a concrete containment building

Indirect products of fission: materials in and around the reactor canbecome radioactive by absorbing neutrons Radioactive wastes: direct + indirect products of fission High-level wastes: direct products of fission

Are highly radioactive Low-level wastes: indirect products of fission

For example, reactor materials Are much less radioactive Include material from hospitals and industry

High doses: radiation can prevent cell division Radiation sickness: exposure (> 1 Sv) prevents replacement or

repair of blood, skin, other tissues Can lead to death in days or months

Low doses: can damage DNA Cells can form tumors or leukemia Damaged eggs or sperm can cause birth defects Effects of exposure may go unseen for 1040 years Other effects: weakened immune system, mental retardation,

cataracts


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Environmental Hazards and Human Health28/04/2012 20:40:00

Pollution: the presence of a substance in the environment that becauseof its composition or quantity prevents functioning of natural processes andproduces undesirable environmental or health effects


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Pollutant: any material that causes pollution Usually by-products of some desirable action Agriculture, comfortable homes, transportation, etc.

Pollution has increased due to population and consumption Along with accumulation of non-biodegradable products (e.g.,

plastic, synthetic organic chemicals)

Environment: the whole context of human life The physical, chemical, and biological setting of where and how

people live Home, air, water, food, workplace, climate, etc.

Hazard: anything that can cause: Injury, disease, death to humans Damage to personal or public property Deterioration or destruction of environmental parts

Health: a state of complete physical, social, and mental well-being Not just the absence of disease or infirmity

Environmental health focuses on disease Health: the absence of disease

Two measures are used to study disease Morbidity: the incidence of disease in a population


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Mortality: the incidence of death in a population Epidemiology: the study of the presence, distribution, and preventionof disease in populations

Centers for Disease Control and Prevention (CDC) Part of the Department of Health and Human Services Provides tools and information to protect health Involved in health risk management and prevention

Each state has its own public-health agency Can require shots, quarantines, monitoring diseases, etc.

The U.S. has a huge health care industry Medicare, Medicaid, hospitals, physicians, etc.

Health policies are limited by information and funding Limited funds should go to strategies that achieve the greatest risk

prevention Countries have access to the WHO

Established by the UN in 1948 Everyone should get the highest possible level of health Staffed by professionals and governed by the World Health

Assembly A universal indicator of health

In 1955, it was 48 years


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It is now 68 years and will rise to 73 by 2025 Longer lives: due to social, medical, economic advances Epidemiologic transition: decreasing death rates accompanydevelopment

Infectious diseases are replaced by diseases of aging But 92 million children still die each year Common diseases kill 47% of people in poor countries

Industry and intensive agriculture have their own hazards

Four classes of environmental hazards: Cultural, biological, physical, chemical

There are two ways to consider hazards to health Lack of access to resources (clean water, food) Exposure to hazards in the environment that brings risk of injury,

disease, or death Cultural hazards: many factors that cause death or disability are amatter of choice

People engage in risky behavior (smoking, drinking, drugs, dontexercise, risky sexual practices, etc.)

Through history, humans have battled bacteria and viruses The black plague and typhus

The 19th century brought vaccinations and bacteriology Bacteriologists discovered most bacterial diseases

The 20th century brought virology, antibiotics, immunizations


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Global eradication of smallpox; victory over polio The battle will never be won

Diseases are inevitable

25% of deaths are due to infectious or parasitic diseases Respiratory infections (diphtheria, influenza, etc.) are the leadingcauses of death in this category

Pneumonia is the most deadly of these diseases Respiratory diseases lead to death in developing nations

Mostly in children already weakened Most children are infected by rotavirus

They die from untreated diarrhea in developing nations Food or water contaminated with bacteria also cause diarrhea

Mycobacterium tuberculosis infects one-third of all people Tuberculosis has resurged due to complacency, HIV-weakened

immune systems, and drug-resistant strains Malaria kills 881,000 people each year

A mosquito infects a person with a protozoan parasite Red blood cells are destroyed, leading to anemia, fever, chills, and

malaise 3.5 billion people suffer from parasitic worms

Hookworms and schistosomes


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Natural disasters include hurricanes, tornadoes, floods, fires,earthquakes, landslides, and volcanic eruptions

The result of hydrological, meteorological, or geological forces Unimaginably dreadful events occurred in 2004-2005

The Indian Ocean tsunami, Hurricane Katrina, Pakistansearthquake

Some hazards cant be anticipated (tornadoes, earthquakes) Others occur because of where people decide to live

Many chemicals are hazardous even at very low levels Heavy metals, organic solvents, pesticides

Acute poisoning episodes are understandable and preventable But it is hard to determine effects of long-term exposure to low

levels of substances Carcinogens: cancer-causing agents

Cancer develops over decades, so it is hard to connect cause withthe effect

There are 51 known and 188 suspected carcinogens Developing nations have rising exposure to chemicals

Carcinogenesis: the development of a cancer It is a process with many steps spread over a long time Five or more mutations must occur to initiate a cancer

Environmental carcinogens bind to, or disrupt, DNA This prevents DNA from functioning


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With a mutation, it may take 40 years to lead to a malignancy Cells grow out of control and form tumors

Which may metastasize (spread) The best strategy is prevention

The tropics have ideal climates for insect-borne diseases Mosquitoes are vectors for yellow fever, dengue fever, elephantiasis,Japanese encephalitis, West Nile, malaria

Malaria is the most serious Control of malaria focuses on vector control: using pesticides on the

Anopheles mosquito Or treatment strategies: curing infected people Malaria has been eradicated in the U.S.

DDT is a successful, yet controversial, control for mosquitoes indeveloping countries

Giving children insecticide-treated nets over their beds reducesmortality from all causes Bed nets, indoor DDT spraying, and effective drugs reduce malariadeaths

A cost-effective, large-scale intervention in Africa The Plasmodium protozoan is becoming resistant to drugs

Chloroquine is now ineffective against malaria ACT (artemisinin combination therapy) is effective

But resistance is appearing


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Airborne pollutants are hard-to-control hazards Hard to measure and avoid

Three categories of impacts Chronic: pollutants cause gradual deterioration of physiological

functioning over years Acute: pollutants cause life-threatening reactions within hours or

days Carcinogenic: pollutants cause cellular changes leading to

uncontrolled growth and division (cancer)

Indoor air pollution can pose an even greater health risk than outdoorair pollution

Inside air can contain much higher levels of pollutants Indoor air pollution in developed countries is problematic

More numbers and types of pollutants are being used Insulated buildings trap pollutants inside People spend more time indoors than out (e.g., children, pregnant

women, the elderly or sick) There are many sources of indoor air pollution

The least excusable is from smoking

Toxicology: the science that studies the impacts of toxic substances onhuman health

It investigates the relationships between substances andenvironmental or health problems


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Water Pollution and Its Prevention 28/04/201220:40:00

Abundant nitrogen promotes growth of phytoplankton (photosyntheticmicroorganisms)


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Zooplankton (microscopic animals) eat phytoplankton These dead organisms are eaten by bacteria, which also consume

oxygen Dead zones last from May to September

Until cold weather mixes the water The gulfs $2.8 billion fishery was affected

Congress passed the 1998 Harmful Algal Bloom and HypoxiaResearch and Control Act

Early in the Industrial Revolution chemicals and sewage were dumpeddirectly into U.S. waterways

Contaminating drinking water and causing disease In the late 1800s, Pasteur and others showed that sewage-bornebacteria caused infectious diseases

Cities implemented sewers and toilets Receiving waters became cesspools

Water became unfit for any recreational use Health problems were not seen as being caused by pollution but as theprice of progress

The Federal Water Pollution Control Act of 1948 The first federal action regarding water pollution Provided technical assistance but nothing else

Waterways became open chemical and waste sewers In 1969, Ohios Cuyahoga River actually caught fire


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The Clean Water Act of 1972 (CWA) Passed by Congress in response to public outrage about polluted

water Charged the EPA with restoring and maintaining the chemical,

physical, and biological integrity of waters One of the most effective environmental laws enacted

Point-source pollution: easy to identify, monitor, and regulate Factories, sewage systems, power plants, underground coal mines,

oil wells Nonpoint-source pollution: poorly defined and scattered

Agricultural runoff, storm-water runoff (streets, parking lots,lawns), atmospheric deposition

Strategies to control water pollution Reduce/remove the source: best for nonpoint sources Treat the water before release: best for point sources

Pathogens: disease-carrying bacteria, viruses, parasites Found in human and animal excrement

Even after symptoms disappear the organism can still carry thedisease Public-health measures prevent diseases

Purification and disinfection of public water supplies Sanitary collection and treatment of wastes Sanitary standards where food is prepared for the public Personal and domestic hygiene practices


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Public-health departments set and enforce standards

Sanitation = good medicine

Organic matter: human and animal wastes Leaves, grass, trash, etc. Most (except plastic and some synthetic chemicals) is

biodegradable Bacteria and detritus feeders consume organic matter and oxygen

Water holds much less dissolved oxygen (DO) than air Cold water holds more DO (10 ppm)

Even a little organic matter can deplete waters DO Bacteria consuming organic matter keep the DO low

(Biochemical oxygen demand ) BOD: a measure of the amount of organic material in water

How much oxygen is needed to break matter down The higher the BOD, the greater the likelihood DO will be depleted

A high BOD limits or precludes animal life A DO < 2 or 3 ppm kills fish and shellfish

Only bacteria can live in anaerobic (no oxygen) conditions A BOD value for raw sewage = 220 ppm

Even 10 ppm can deplete water of DO


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Inorganic chemicals: heavy metals (lead, mercury, arsenic, nickel),acids from mine drainage or precipitation

Road salts used to melt ice and snow

Organic chemicals: petroleum, pesticides Industrial chemicals: polychlorinated biphenyls (PCBs), cleaning

solvents, detergents Many chemicals are toxic at very low levels

Biomagnification: chemicals become concentrated when going upthe food chain

Higher concentrations change water chemistry

Land weathering and storms wash sediments into water Erosion from farms, deforestation, overgrazing, construction,

mining, roads increases sedimentation Clear water supports complex food webs

Organisms attach to rocks or hide behind them to prevent washingdownstream

Clay and humus make water muddy Reducing light penetration and photosynthesis

Settled material coats everything, reducing photosynthesis Smothering gills, feeding structures, and eggs

Bed load: destructive sand and silt that is not suspended, but iswashed along the bottom Rolling particles scour organisms from rocks

Smothering bottom life


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Filling in hiding places Plants cant become established on the shifting sand

Storm-water management reduces bed load with drains Some housing developments have ponds to trap runoff

Water infiltrates the soil, creating wetlands

Nutrients: inorganic materials that are essential for plants Phosphorus and nitrogen: the two most important nutrients

Limiting factors if they are in short supply Nutrients become pollutants when they stimulate undesirable plantgrowth in water Point sources: untreated or poorly treated sewage outfalls

Particularly in developing countries Nonpoint sources: agriculture (fertilizers, manure, crops, irrigationwater), lawns/gardens, golf courses, drains

Many pollutants are in water only because of humans Pesticides, solvents, detergents

Others occur naturally and become a problem under certain conditions Nutrients, sediments

Pollution: any quantity that is harmful to human health or the

environment It prevents full use of the environment

The concentration, not presence, of a substance is the concern


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National Recommended Water Quality Criteria Provides standards for assessing pollution

Criteria pollutants: the EPAs list of 167 substances Toxins, nutrients, hardness, pH Identifies and recommends concentrations for all water

Criteria maximum concentration (CMC): the highest singleconcentration beyond which impacts occur Criterion continuous concentration (CCC): highest sustainedconcentration beyond which impacts occur States used these criteria to uphold pollution laws

Drinking Water Standards and Health Advisories: the EPAs table of standards for 94 contaminants

Enforceable under the Safe Drinking Act (SDWA) Presented as maximum contaminant levels (MCLs)

Arsenic: a known human carcinogen occurring naturally ingroundwater

Drinking waters MCL was 50 g/L (1 g/L = 1 ppb) Scientists warned this was much too high After political delays, the EPA lowered it to 10 g/L

National Pollution Discharge Elimination System (NPDES): addressespoint-source pollution

Permits for regulating wastewater and industrial discharges Total Maximum Daily Load (TMDL) program: evaluates all sources

(mainly nonpoint) of water pollutants


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Accounts for the waters ability to assimilate the pollutant 92% of U.S. peoples drinking water meets drinking water standards

42,000 rivers, lakes do not meet water quality standards Over 60% of U.S. waters have not been assessed at all

Primary treatment: removes debris and grit

Bar screen: mechanically rakes debris for removal and incineration Grit chamber: grit is allowed to settle and is removed Primary clarifiers: tanks where particulate matter settles to the

bottom and fatty/oily materials float Raw sludge: particulates and oily materials that must be treatedseparately

Organisms feed on colloidal and dissolved organic matter Decomposers and detritus feeders Oxygen is added to enhance respiration and growth

Trickling filter system: primary treated water is sprinkled onto a bed of rocks 68 feet deep

Bacteria, protozoans, rotifers, worms, etc. Activated sludge system: the most common treatment

Primary treated water enters a tank with an air bubbling system or

paddles

Activated sludge: a mixture of detritus-feeding organisms Added to water as it enters the tank


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Organisms reduce the biomass (including pathogens) Floc: clumps of organisms that settle in still water

Secondary clarifier tank: organisms settle out 90% of organic material has been removed

Settled organisms (activated sludge) are pumped back into theaeration tank

Excess activated sludge is added to the raw sludge Organisms oxidize material to CO 2, H 2O, nutrients

BNR ( Biological nutrient removal ): a secondary activated-sludgesystem

Removes nutrients and oxidizes detritus Nitrogen removal: bacteria convert ammonia and nitrate to non-nutritive nitrogen gas (denitrification)

The activated sludge system is partitioned into zones that promotethe denitrifying process

Phosphorus: is taken up and stored by bacteria Bacteria are then added to the raw sludge

Alternatives to BNR: chemical treatments use lime, ferric chloride, or apolymer to remove phosphorus

Wastewater is disinfected by: Chlorine gas: effective, cheap, but dangerous to work with and

harms aquatic life Sodium hypochloride (Chlorox): a safer way to add Cl Ozone gas: kills microorganisms but must be generated (costly and

energetically expensive) Ultraviolet light: kills microorganisms but little else


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Discharged wastewater has low BOD and may improve water quality Many areas still use only primary, or no, treatments

Raw sludge: particulate matter that settles out or floats to the surface

during primary treatment Includes excesses from activated-sludge and BNR A gray, foul-smelling, syrupy liquid, 97% water May contain pathogens

Sludge may be used as organic material If it contains no pathogens and no toxic contaminants

Sludge is converted to organic fertilizer through anaerobic digestion,composting, and pasteurization

It does not remove heavy metals or toxins

Composting: mixing raw sludge with water-absorbing material toreduce the water content

Windrows: long, narrow piles of compost that allow air to circulate Bacteria and other decomposers break down material into rich

humuslike material for treating poor soil Pasteurization: dewatered raw sludge is dried in ovens

Kills pathogens The dry, odorless pellets are sold as organic fertilizer

The septic tank and leaching field: the most common and traditionalsystem

Wastewater flows into tanks where particulates settle and aredigested by bacteria


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Accumulations are periodically pumped out Water, organic material, and dissolved nutrients flow into a leachingfield and percolate into the soil

Soil bacteria decompose the matter Gardens can be planted over leaching fields

Nutrient-rich water from secondary treatment is beneficial for growingplants

Keep it out of waterways, but use it on fields Effluents must not contain toxic materials

Cities irrigate open space, lawns, golf courses with effluent Money from selling the water offsets operating costs

Developing countries use untreated sewage to irrigate crops Growing crops but spreading disease Only treated effluents should be used

In lakes and ponds less than 68 feet deep, SAV can reach thesurface, totally covering the water body with a thick mat of vegetation

Boating, fishing, swimming are impossible Dead mats sink and create a BOD that depletes the dissolved oxygen

Killing all organisms, except for bacteria Natural eutrophication: part of the process of natural succession Cultural eutrophication: accelerated eutrophication caused by humans


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Poor farming, urban runoff, sewage

All of these methods are temporary They have to be repeated often and at significant cost

Applying herbicides: to control phytoplankton and SAV Herbicides also kill fish and aquatic animals Rotting vegetation depletes oxygen, killing more fish Vegetation rapidly regrows

Aerating: plastic tubes with tiny holes dissolve bubbles in the water A costly way to break down detritus

Harvesting: bottom-rooted plants in shallow lakes or ponds reach andsprawl over the surface

Plants are removed mechanically or by hand The plants make good fertilizer and mulch Since roots are left, vegetation soon grows back

Drawing water down: kills most rooted plants But they grow back

Long-term strategies to reduce nutrients and sediments Identify the source Develop and implement strategies for correction


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Each watershed must be separately analyzed The concept of limiting factors: the lack of one nutrient can suppressgrowth

Phosphorus (phosphate): in freshwaters Nitrogen (nitrate, ammonium ion): in marine systems

The EPA has the responsibility of overseeing U.S. waters But it can develop regulations only if Congress gives it the authority

The Clean Water Act of 1972 (CWA): gives the EPA jurisdiction over(and requires permits for) all point sources of pollution

$78 billion helps cities and towns build treatment plants The Clean Water State Revolving Fund (SRF): provides direct grants tobuild treatment facilities

Money paid back goes as loans to others

Congress is debating: Whether the act should be strengthened or weakened If regulations intrude on private property rights How regulatory relief should be given to industries, cities, and

people How to deal with the TMDL program

For the past 20 years, Congress has reauthorized the CWAs provisionsand kept the status quo


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Hazardous Chemicals: Pollution and Prevention28/04/2012 20:40:00

Toxicology: the study of the harmful effects of chemicals on humanand environmental health Toxicologists study acute toxicity effects, chronic effects, and

carcinogenic potential Data on toxic chemicals comes from

The National Toxicology Program (NTC) The Chemical Repository The National Institute of Environmental Health Sciences (NIEHS) The EPAs Integrated Risk Information System (IRIS)

The dose (level of exposure multiplied by the length of time of exposure) is linked with the response (effects)

If a chemical has a low toxicity, concern centers on chronic orcarcinogenic effects

Human exposure to a hazard is a vital part of risk characterization Exposure comes from the workplace, food, water, and environment It is hard to get an accurate determination of exposure

There is usually a threshold level in the dose-response relationship Organisms can usually deal with some level of a substance without

suffering ill effects Threshold level: the level below which there are no ill effects

Effects above this level depend on concentration and duration of exposure

It is high for short exposures, and lower as time increases


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The EPA takes a zero-dose, zero-response approach for carcinogens There is no evidence of a threshold level for them But lower doses are less likely to produce cancers

The field of toxicology is well established It is the most important source of sound science for supporting

regulations from the EPA and FDA The NTP was established in 1978

The worlds leader in assessing chemical toxicity and carcinogenicity

Hazardous material (HAZMAT): a chemical that presents a certainhazard or risk (excluding radioactive materials) Ignitability: substances that catch fire readily (gasoline) Corrosivity: substances that corrode tanks and equipment (acids)


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Reactivity: chemically unstable substances May explode or create toxic fumes if mixed with water (explosives,

sulfuric acid) Toxicity: substances that are injurious when eaten or inhaled (chlorine,

pesticides, etc.)

Total product life cycle: encompasses all steps in a materials life fromraw materials to disposal Chemical wastes and by-products are inevitable Over 80,000 chemicals are registered in the U.S.

They enter the environment at every stage Chemicals enter the environment directly (e.g., fertilizers)

Parts are left behind (e.g., evaporation of solvents) Through use (e.g., lubricants, solvents) Through energy use (gasoline, coal, etc.) Through accidents or spills

Industry, small shops, and homes release chemicals Toxic Release Inventory (TRI): provides an annual record of releasesof 650 chemicals by 22,000 facilities

Total releases have declined by 61% since 1990 The Emergency Planning and Community Right to Know Act (EPCRA1986)

Industries must report releases of toxic chemicals to theenvironment

The Pollution Prevention Act (1990): mandates collection of data of chemicals treated on-site

Halogenated hydrocarbons: synthetic organics that contain halogens:chlorine, bromine, fluorine, iodine Chlorinated hydrocarbons (organic chlorides): the most commonhalogenated hydrocarbons

Plastics, pesticides (DDT), solvents (carbon tetrachloride),insulation (polychlorinated biphenyls)

Most dirty dozen POPs are halogenated hydrocarbons All are toxic and cause cancer in animals


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Many are endocrine disrupters at low levels Banned or restricted by the 2004 Stockholm Convention

The Clean Air and Clean Water Acts ended disposal of hazardous

wastes into the air and water So companies turned to unregulated land disposal

Three land disposal methods were used in the 1970s Without regulations or enforcement, groundwater contamination

was inevitable Deep-well injection: boreholes are drilled thousands of feet belowgroundwater into porous formations

A well contains pipes and casings that isolate wastes The well is sealed at the bottom to prevent backup

The Resource Conservation and Recovery Act (1996) prompted theEPA to study surface impoundments The 2007 TRI reported 781 million lbs of toxics released to on-site(disposal by producers on their own facilities) surface impoundments

18,000 surface impoundments exist at 7,500 facilities Two-thirds of impoundments contain materials with carcinogenic

and other human health concerns Most impoundments are only a few meters above groundwater, and

more than half lack liners ` RCRA sets standards for disposal of wastes in landfills

Concentrated liquids or solids are put into drums Best-demonstrated available technologies (BDATs)

Treatment standards for wastes are set by the EPA Reduce chemical toxicity and mobility Technologies include stabilization and incineration, chemical

oxidation, and other specific techniques Only 23 landfills in North America receive off-site hazardous wastes

Received 403 million lbs in 2007


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Orphan sites: some companies or individuals stored wastes on theirown property, then went out of business, abandoning the property andwastes

Leaking drums could cause explosions and fires Valley of the Drums (VOD): in Kentucky

One of the most famous abandoned sites Love Canal, New York: brought the problem of unregulated dumping tothe publics attention

The absence of public policy made the situation worse

Contaminated drinking water: a major public health threat The first priority: ensure that people have safe water Second: clean up or isolate the pollutions source to prevent further

contamination The Safe Drinking Water Act (1974): the EPA set national standards toprotect public health

Including allowable levels of specific contaminants Maximum contaminant levels (MCLs): if contaminants exceed thislevel, the water source is closed

The EPA has jurisdiction over groundwater, too Groundwater remediation: a developing technology used if toxicmaterials have contaminated groundwater

Techniques involve drilling wells, pumping out contaminated water,purifying it, and reinjecting it

Cleaning up the source of the water is mandatory If contamination is severe, remediation may not be possible

Groundwater is considered unfit for drinking


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The trust pays for identification of sites, protection and remediation of groundwater, and cleanup of sites Superfund Amendments and Reauthorization Act (SARA; 1986):

greatly expands the Superfund program All sites cannot be cleaned up, so priorities must be set All sites are identified, and threats to groundwater are determined

If no immediate threat exists, nothing else is done If a threat exists, measures are taken to protect the public by

isolating the wastes

National Priorities List (NPL): contains the worst sites These sites are scheduled for total cleanup The site is evaluated to determine the most cost-effective way to

clean it up Efforts are made to identify potential responsible parties (PRPs) Industries are invited to help pay or participate in cleanup

activities

Soil contaminated with toxic organic compounds does not degrade The soil lacks organisms and/or oxygen

Bioremediation: another cleanup technology Oxygen and organisms are injected into the site The organisms feed on and eliminate the pollutants Then they die


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Phytoremediation: using plants to decontaminate heavy metal-contaminated soil

Plants stabilize the soil and reduce movement of contaminants byerosion

They also extract the contaminants by direct uptake The plants are removed and treated as toxic waste The process can be slow and is only used where contamination is nottoxic to plants

Sunflowers capture uranium, poplar trees soak up dry-cleaningsolvents, ferns thrive on arsenic

Brownfields: a highly successful Superfund development Abandoned, idled, or underused industrial or commercial facilities Expansion or development is hampered by real or perceived

environmental contamination Hazards not serious enough to be on Superfund NPL still impair $2trillion worth of real estate The Brownfield Act (2002) gives grants for site assessment andremediation work

Limits liability for owners of contaminated land

The Resource Conservation and Recovery Act (1976) Cornerstone legislation designed to prevent unsafe or illegal

disposal of all solid wastes on land All disposal facilities (e.g., landfills) must have permits

Facilities must have safety features Old facilities are shut down and become Superfund sites

Toxic wastes destined for landfills must be converted to forms that willnot leach Requires cradle-to-grave tracking of hazardous wastes


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Industries used to force workers to do jobs that exposed them tohazardous materials without informing them of the dangers involved Occupational Safety and Health Act of 1970

Its amendments make up the hazard communication standard(workers right to know)

Workers right to know: businesses, industries, and labs must makeinformation on hazardous materials available

Along with providing suitable protective equipment

Material safety data sheets (MSDSs): give information on over 600chemicals when they are shipped, stored, and handled

Contain information on reactivity and toxicity Tell what precautions to follow when using the chemical

It is the workers responsibility to read the information and exerciseprecautions

In the past, substances were introduced without testing for side effects The Toxic Substances Control Act (TSCA; 1976): before a chemical canbe bulk produced, manufacturers must submit a pre-manufacturing notice to the EPA

It details potential environmental and health risks The EPA may restrict or prohibit the product

The EPA must use the least burdensome approach Compare the costs and benefits of regulation

It is the fair treatment and involvement of all people Equal enforcement of environmental laws, regulations, and policies

regardless of race, color, etc.


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No group of people should bear a disproportionate share of negativeenvironmental consequences Hazardous facilities are more likely to be located in areas where mostresidents are non-Caucasian and poor

The rich generate wastes but dont want them close

President Clinton issued an executive order in 1994 focusing agencyattention on environmental justice (EJ) The EPAs EJ program has awarded millions to organizations and localgovernments addressing EJ issues International EJ: some developing countries import hazardous wastesfrom developed countries for money The Basel Convention: an international agreement banning mostinternational toxic-waste trade The Basel Action Network publicizes and coordinates legal challengesto waste shipments

ETM Final Notes

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