Studied by 12 people
air pollution
The introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems. The air pollution system has many inputs and outputs.
sulfur dioxide pollutant (SO2)
A corrosive gas that comes primarily from combustion of fuels such as coal and oil.
A respiratory irritant, can adversely affect plant tissue.
Also released in large quantities during volcanic eruptions and in much smaller quantities, during forest fires.
nitrogen oxides pollutants (NOx)
Motor vehicles and stationary fossil fuel combustion are the primary anthropogenic sources of nitrogen oxides.
Respiratory irritant, increases susceptibility to respiratory infection.
An ozone precursor, leads to formation of photochemical smog.
Converts to nitric acid in atmosphere, which is harmful to aquatic life and some vegetation.
Contributes to over-fertilizing terrestrial and aquatic systems.
carbon oxide pollutants (COx)
Carbon monoxide (CO) is a common emission in vehicle exhaust and most other combustion processes.
CO can be a significant component of air pollution in urban areas.
Carbon dioxide (CO2) released by burning fossil fuels has led to its becoming a major pollutant.
CO2 recently exceeded a concentration of 400 parts per million in the atmosphere and appears to be steadily increasing each year.
particulate matter (PM)
Solid or liquid particles suspended in air. Also known as Particulates; Particles.
Particulate matter can be natural or anthropogenic (human made).
Particulate matter in the atmosphere ranges considerably in size and can absorb or scatter light, which creates a haze and reduces the light that reaches the surface of the Earth.
haze
reduced visibility
photochemical oxidant
a class of air pollutants formed as a result of sunlight acting on compounds such as nitrogen oxides
ozone (O3)
a secondary pollutant made up of three oxygen atoms bound together
smog
a type of air pollution that is a mixture of oxidants and particulate matter
photochemical smog
smog that is dominated by oxidants such as ozone. also known as Los Angeles-type smog; brown smog.
lead
A gasoline additive, also found in oil, coal, and old paint.
Impairs central nervous system.
At low concentrations, can have measurable effects on learning and the ability to concentrate.
volatile organic compound (VOC)
An organic compound that evaporates at typical atmospheric temperatures.
Formed by evaporation of fuels, solvents, paints, and improper combustion of fuels such as gasoline.
A precursor to ozone formation.
primary pollutant
A polluting compound that comes directly out of a smokestack, exhaust pipe, or natural emission source.
Examples include CO, CO2, SO2, NOx, and most suspended particulate matter.
secondary pollutant
A primary pollutant that has undergone transformation in the presence of sunlight, water, oxygen, or other compounds.
Examples include O3, sulfate, and nitrate.
primary and secondary air pollutants
The transformation from primary to secondary pollutant requires a number of factors including sunlight, water (clouds), and the appropriate temperature.
air pollution comes from both natural and human resources
Natural emissions of pollution including volcanoes, lightning, forest fires, and plants (both living and dead), all release compounds that can be classified as pollutants.
Anthropogenic (human made) sources include on-road vehicles, power plants, industrial processes, waste disposal (incinerator).
anthropogenic emission
In the United States, emissions from human activity are monitored, regulated, and in many cases controlled.
The clean air act and its various amendments require that EPA establish standards to control pollutants that are harmful to human health and welfare.
Through the national ambient air quality standards (NAAQS) the EPA periodically specifies concentration limits for each air pollutant.
On-road vehicles are the largest source of carbon monoxide and nitrogen oxides.
The major source of anthropogenic sulfur dioxide is the generation of electricity primarily through coal.
Among the sources of particulate matter are road dust, industrial processes, electricity generation, and natural and human-made fires.
photochemical smog remains an environmental problem in the US
The formation of this photochemical smog is complex and still not well understood.
A number of pollutants are involved and they undergo a series of complex transformations in the atmosphere.
chemistry of ozone & photochemical smog formation
In the absence of volatile organic compound (VOC), ozone will form during the daylight hours.
After sunset, the ozone will break down.
In the presence of VOCs ozone will form during the daylight hours.
The VOCs combine with nitrogen oxides to form photochemical oxidants, which reduce the amount of ozone that will break down later and contribute to prolonged periods of photochemical smog.
thermal inversion
A situation in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below.
Thermal inversions that create pollution events are particularly common in some cities, where high concentration of vehicles exhaust and industrial emissions are easily trapped by the inversion layer.
inversion layer
The layer of warm air that traps emissions in a thermal inversion.
The warm inversion layer traps emissions that then accumulate beneath it.
acid deposition
Lowers the pH of lake water, decreases species diversity of aquatic organisms, mobilized metals that are found in soils and releases them into surface waters, and damages statues, monuments, and buildings.
Occurs when nitrogen oxides and sulfur oxides are released into the atmosphere and combine with atmospheric oxygen and water. These form the secondary pollutants nitric acid and sulfuric acid.
The secondary pollutants further break down into nitrate and sulfate, and hydrogen ions (H+) which cause the acid in acid deposition.
Acid deposition has been reduced in the US as a result of lower sulfur dioxide and nitrogen oxide emissions.
how acid deposition forms and travels
The primary pollutants sulfur dioxide and nitrogen oxides are precursors to acid deposition.
After transformation to the secondary pollutants, dissociation occurs in the presence of water.
The resulting ions (hydrogen, sulfate, and nitrate) cause the adverse ecosystem effects of acid deposition.
ways to avoid pollution
Prevention technology and innovation.
Avoid emissions in the first place.
Use cleaner fuel.
Increase efficiency.
Control pollutants after combustion.
the scrubber
In this air pollution control device, particles are “scrubbed” from the exhaust stream by water droplets.
A water-particle “sludge” is collected and processed for disposal.
stratospheric ozone is beneficial to life on earth
The stratospheric ozone layer exists roughly 45-60 kilometers above earth.
Ozone has the ability to absorb ultraviolet radiation and protect life on earth.
The UV spectrum is made up of three increasingly energetic ranges: UV-A, UV-A, and UV-C.
formation of stratospheric ozone
UV-C radiation breaks the molecular bond holding an oxygen molecule together: O2 + UV-C → O + O
A free oxygen atom produced in the first reaction encounters an oxygen molecule, and they form ozone: O + O2 → O3
Both UV-B and UV-C radiation can break a bond in this new ozone molecule: O3 + UV-B or UV-C → O2 + O
breakdown of stratospheric ozone
When chlorine is present (from CFCs; aerosol and such), it can attach to an oxygen atom in an ozone molecule to form chlorine monoxide (ClO) and O2: O3 + Cl → ClO + O2
The chlorine monoxide molecule reacts with a free oxygen atom, which pulls the oxygen from the ClO to produce free chlorine again: ClO + O → Cl + O2
A single chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules until finally one chlorine atom finds another and the process is stopped.
In the process, the ozone molecules are no longer available to absorb incoming UV-B radiation.
As a result, the UV-B radiation can reach Earth’s surface and cause harm to biological organisms.
indoor air pollution
A significant hazard in developing and developing countries.
Worldwide, approximately 4 million deaths each year are attributable to indoor air pollution.
90% of these deaths are in developing countries, and more than 50% are children.
indoor air pollution in developed countries
A typical home in the US may contain a variety of chemical compounds that could, under certain circumstances, be considered indoor air pollutants.
Household products, pesticides, paint, furniture, carpets, foam insulation, pressed wood, tobacco smoke, oil paint, floor and ceiling tiles, pipe insulation, fireplaces, wood stoves.
most indoor air pollutants differ from outdoor air pollutants
Indoor air pollutants include:
Carbon monoxide from malfunctioning heating equipment.
Asbestos - a long thin fibrous silicate mineral with insulating properties, which can cause cancer when inhaled; formerly used as insulation in buildings.
Radon that seeps into homes through cracks in the foundation, groundwater, or rocks.
VOCs used in furniture, paint, and building materials.
VOCs in home products
Reasons for sick building syndrome:
Inadequate or faulty ventilation.
Chemical contamination from indoor or outdoor sources.
Biological contamination from outside or inside.
water pollution
Contamination of streams, rivers, lakes, oceans or groundwater with substances produced through human activities.
Point source = Comes from distinct places (ex. sewage treatment plant).
Non-point source = More diffused, large areas (ex. farming region).
human wastewater
Produced by human activities including sewage from toilets and gray water from washing clothes and dishes.
Oxygen demanding waste = Organic matter that feeds the growth of microbes that are decomposers.
biochemical oxygen demand (BOD)
The amount of oxygen a quantity of water uses over a specific time at a specific temperature.
Low BOD is less polluted (5-20 mg of O2).
High BOD such as wastewater (200+ mg of O2)
Dead zones = very little amount of oxygen therefore organisms die.
Nutrient release.
Nitrogen and phosphorous can be released into bodies of water from agriculture run-off.
eutrophication
An overabundance of growth due to excess nitrogen and phosphorous.
Causes algal blooms.
When the algae dies the zooplankton feed off the dead algae.
Mississippi river receives water from 41% of the land in the US.
disease causing organisms
Pathogens: parasites, bacteria, viruses that cause illness (ex. cholera, hepatitis, and typhoid fever).
1.1 billion people do not have access to clean drinking water.
42% of the world’s population lacks proper sanitation and over half live in China and India.
testing water
Use indicator species to determine if there are pathogens in the drinking water.
Indication species indicate whether or not disease-causing pathogens are likely to be present.
Fecal Coliform Bacteria = live in the intestines of humans, generally harmless.
E. Coli is an indicator species.
treating wastewater
Bacteria break down the organic matter into carbon dioxide and inorganic compounds such as nitrate and phosphate.
septic tanks
Large container that receives wastewater from the house.
Heavy material sinks, light material floats, and the fairly clear layer is septage.
Septage goes to a leach field where it slowly seeps out across the field and is purified by the soil.
Uses no electricity but has to be pumped.
sewage treatment plants
Good for large areas.
Series of underground pipes.
Primary treatment:
Solid wastes settles out, is dried and classified as sludge. Sludge is exposed to bacteria to digest it. Final form is placed in a landfill or burned. Can be converted into fertilizer pellets.
Secondary treatment:
Bacteria breaks down 85-90% of all the organic matter into carbon dioxide, nitrogen and phosphorous. Aeratoin to promote aerobic bacteria growth. Remaining water is disinfected using chlorine, ozone, or UV light. Placed into nearby river, lake, or ocean back to the water cycle.
Tertiary Treatment:
Takes out the nitrogen and phosphorous to prevent algal blooms.
legal sewage dumping
Older treatment plants receive water from storm-water drainage systems.
Heavy rains overwhelm the capacity of the plants.
Treatment plants are allowed to bypass the normal treatment protocol and pump sewer water directly into the adjacent body of water.
This happens 40,000x per year in the US.
500,000 illnesses per year are due to drinking sewage-contaminated water.
animal feed lots and manure lagoons
Manure lagoons are large, human-made ponds lined with rubber to prevent the manure from leaking into groundwater.
Manure contains bacteria, hormones, and antibiotics.
After broken down by bacteria can be spread over fields as fertilizer.
Can leak or overflow, fertilizer can run off. All present health issues and concerns.
arsenic
Occurs naturally in the earth’s crust.
Can dissolve into the groundwater.
Mining can release arsenic.
Used in industry as a wood preserver.
Can be removed from water through filtration.
Associated with cancer to skin, lungs, kidneys, and bladder.
Upper limit recently set to 10 ug/L
Big issue in India.
mercury
Found in water due to increased human activities.
Released when burning coal.
Incinerating garbage, hazardous waste, medical supplies and dental supplies also contributes.
Raw materials from making cement also contains mercury.
Petroleum exploration leads to mercury and lead pollution.
Mercury (Hg) is converted into methylmercury by bacteria.
Methylmercury is very harmful, bad for children and developing fetuses.
acid deposition & acid mine drainage
Burning fossil fuels releases sulfur dioxide and nitrogen dioxide into the air.
These are released into the atmosphere and converted into sulfuric acid and nitric acid.
They are transported to other areas (precipitation or dry parcels) and released back into the environment.
Lowers the pH of water bodies from 5.5 or 6 to below 5!
Coal scrubbers pass the hot gases through limestone to remove the acidic gases.
Abandoned underground mines flood with ground water producing acidic water.
Low pH harms organisms.
synthetic organic compounds
Pesticides and inert ingredients.
Pesticides control pest organisms.
Includes herbicides, fungicides, and insecticides.
Kill more than the intended organisms.
Pose side effects.
pharmaceutical and hormones
US geological survey tested 139 streams across the US for various chemicals.
50% contained antibiotics and reproductive hormones, 80% contain nonprescription drugs. and 90% contained steroids.
Low amounts were detected.
military compounds
Perchlorates used for rocket fuel contaminate the soil and water.
Can effect thyroid gland and the amount of hormones.
industrial compounds
Compounds used in manufacturing are dumped into rivers.
Cuyahoga river in Ohio caught on fire in 1969.
PCBs = polychlorinated biphenyls. Used in manufacturing plastics and insulating electrical transformers until 1979.
Ingested PCBs are lethal and carcinogenic.
General Electric dumped 1.3 million pounds of PCBs into the Hudson River from 1947-1977.
EPA ruled that the company had to dredge and remove 2.65 million cubic yards of PCB sediment. Removal began in 2009.
polybrominated diphenyl ethers (PBDEs)
Flame retardants added to a variety of items.
Since the 1990s scientists have been detecting PBDEs in unexpected places such as fish, aquatic birds, and human breast milk.
Exposure to some types can cause brain damage.
Banned in the European Union and several states including Washington and California.
oil pollution
Oil is toxic to many marine organisms including fish, birds, mammals, in addition to algae and microorganisms at the bottom of the food chain.
Oil is viscous and can spread below and across surfaces.
Source: off-shore oil drilling (drilling under the sea).
About 5,000 off shore oil drilling platforms in the US.
3,000 in the rest of the world.
Can experience leaks.
Estimate 146,000 Kg of oil leaking just in the US.
Foreign: 0.6 million to 1.4 million Kg per year.
BP oil spill 2010
Deepwater Horizon platform caused a pipe to break about 1 mile down.
Pipe was open from April to August.
Estimated 206 million gallons of oil leaked; disrupting beaches, wildlife and estuaries.
Exxon Valdez 1989
Ran aground off of the coast of Alaska.
Spilled 11 million gallons of oil.
Killed 250,000 seabirds, 2,800 sea otters, 300 harbor seals, and 22 killer seals.
20 years later, research has indicated that some species such as bald eagles and salmon have rebounded. Killer whales and sea otters have not. :(
Could take 100 years for the oil to break down.
oil remediation
Oil on feathers must be cleaned by hand.
Feathers covered with oil become heavy and do not insulate.
Plastic barriers can be used to contain oil in one area and then can be sucked off.
Chemicals can be used to break up the oil, but can be harmful to the environment.
Genetically engineered bacterias = bioremediation.
No clear way of how to remove oil from the coastline.
High pressure hot water removes the oil but also the organisms that reside on the rocks and the sediments that contain valuable sediments.
Leaving it there results removal due to the action of the waves, but a lot remains within tiny crevices harming wildlife.
non-chemical pollutants
Garbage!
Great pacific garbage patch = ocean gyre that collects garbage.
Due to rotating currents collects garbage in one concentrated area.
About the size of Texas.
Coal and ash slag that remains when coal is burned (mercury, arsenic, and lead).
sediment pollution
House building, agriculture, and industrial building all increase sediment pollution.
Increases turbidity (clarity) of water which decreases sunlight infiltration.
Can clog fish gills and inhibit the ability to obtain oxygen and catch prey.
Estimate $16 billion per year in the US due to sediment pollution.
thermal pollution
Substantial change in the temperature of the water due to human activities.
Heating up fresh water to facilitate and industrial process then returning this warm water back to the original source.
Cooling machines.
Organisms can suffer from thermal shock.
High temps cause organisms to increase their respiration and warmer water does not contain as much dissolved oxygen as cold water.
EPA regulates how much heated water can be returned to natural sources.
Challenging in the summer when temps are high, AC demands are high, and water levels are low.
Some industries use cooling towers (rely on evaporation) or recycles the water they utilize.
noise pollution
Sounds from ships and submarines disrupt sea life communication.
Sonar is especially bad.
Several beached whales have been connected to the use of military sonar and loud, underwater air guns.
clean water act
The federal water pollution control act of 1948 was the first major piece of legislation affecting water quality.
Expanded in 1972 to the clean water act.
Supports the “protection and propagation of fish, shellfish, and wildlife and recreation in and on the water” by maintaining and when necessary, restoring the chemical, physical, and biological properties of natural waters.
Does not include groundwater.
More recently includes the diversity of living organisms.
Issues water quality standards that define acceptable limits of various pollutants in US waterways.
EPA and state governments can issue permits to control how much pollution industries can discharge into the waters.
safe drinking water act
Sets the national standards for safe drinking water.
EPA is responsible for establishing maximum contamination levels (MCL) for 77 different elements or substances in both surface water and groundwater.
Subject to political pressures.
Expensive for communities to afford.
Successful program but could use some improvements.
legislation in the developing world
Clear difference between developing world and developed nations.
In developed worlds industrialization occurred 100s of years ago with high amounts of pollutions, focus now is for regulation and cleanup.
Developing countries are still within industrialization so suffer higher amounts of pollution.
India, China and Africa are undergoing rapid industrialization.
types of solid waste
Municipal
Non-Municipal
Hazardous
sources of solid waste in the US
Mining 75%
Agriculture 13%
Industry 9.5%
Municipal 1.5%
Sewage sludge 1%
hazardous waste
From both municipal and non-municipal.
Such as carcinogens, mutagenic, tetragenic.
options for disposal
Landfills, exporting, incinerating.
how municipal solid waste was disposed of in 1996
Sanitary landfills 55.7%
Incineration 16.7%
Recycling 23.8%
Composting 3.8%
open dump
Big pile where you drop off trash.
Common in developing countries, illegal in developed countries.
Disease, rodent problems, groundwater pollution, organisms eat trash and spread illness.
Sanitary landfills
Dig giant hole
Line hole with plastic liner
Place solid waste in hole
Cover each day with 6” soil
Only newer ones have lining (15%).
Possible leakage to groundwater if liner rips.
incineration
Trash is burned and heat is used to generate electricity.
CO, particulate matter, and heavy metals are released.
Control devices must be installed such as scrubbers and precipitators ().
Ash produced goes to landfills.
integrated waste management
Goal is to minimize waste.
Reuse reduce recycle.
hierarchy of waste disposal
(from most preferred to least preferred)
Source reduction
Reuse
Recycling
Resource recovery
Incineration
Landfilling
reducing waste
Reduce consumption, reduce packaging, trash taxes, photo/biodegradable plastics.
recycling
Turning discarded materials into new materials.
Pros: reduces virgin resource use, frees up landfill space, less deforestation, less habitat loss.
Cons: expensive for cities to start, trucks create CO2, more expensive products, recycling plants create CO2 → global warming.
resource conservation and recovery act
Federal law in US governing the disposal of solid and hazardous wastes.
“Cradle to grave” tracking on hazardous materials.
climate change
Climate change refers to any significant change in the measures of climate lasting for an extended period of time. In other words, climate change includes major changes in temperature, precipitation, or wind patterns, among other effects, that occur over several decades or longer.
global warming
Global warming refers to the rise in global average temperature near earth’s surface. It is caused mostly by increasing concentrations of greenhouse gases in the atmosphere. Global warming is causing climate patterns to change. However, global warming itself represents only one aspect of climate change.
mechanisms of long term climate change
Albedo effects (ability of surfaces to reflect sunlight).
Solar forcing (Variations in the shape of the earth’s orbit can affect the distribution of incoming radiation - and various feedbacks might amplify these changes, causing global climatic change).
Volcanism or extra-terrestrial impacts.
Changes in atmospheric or oceanic composition of circulation.
how is climate change measured and predicted
Past - how has the climate changed throughout Earth’s history?
Present - assessing the current state of global climate.
Future - projecting trends into the future.
radiocarbon dating (past)
A method for determining the age of an object containing organic material by using the properties of radiocarbon.
14C is formed in the upper atmosphere at a constant rate and is mixed with 12C such that the atmospheric 14C12C ration is constant.
Atmospheric CO2 is absorbed by plants in photosynthesis, and hence radiocarbon is present in the biosphere in the same proportion as in the atmosphere.
After death, no more 14C is incorporated into subfossil material.
14C decays radioactively at a constant rate
dendroclimatology (past)
Using tree rings to assess past climatic conditions.
Properties such as width and maximum latewood density show what years were more favorable for growth.
Radiocarbon dating can be used to cross-reference ages.
varve deposits (past)
Annual deposition from sediments under glacial lakes.
Can be used to assess past climatic conditions.
Thicker bands = more melting = hotter and wetter,
ocean sediment layers (past)
Contain evidence of past climate change and ice volume.
Nearly continuous records untouched by humans and other erosive processes.
Forams are preserved in marine sediments for millions of years.
A sediment core represents a record of ocean conditions through time.
sediment analysis using foraminifers (foram) (past)
Forams accumulate oxygen isotopes in proportion to the isotopic composition of seawater, and so contain a high proportion of heavy 18O during glacials, when sea level is low.
The ratio of 18O:16O is expressed as ∂18O.
Laboratory analyses of fossil forams yield ∂ 18O measurements for the whole period covered by the core.
ice core stable isotopes (past)
Temperature at the time of snow formation determines the isotopic composition of ice.
H2O is made up of two atoms of 1H or 2H and one atom of 16O, 17O, or 18O.
Isotopic fractionation (modification of the ratio of different isotopes) occurs during the transformation from atmospheric water vapor to the ice in snowflakes.
In Antarctica, the ratio of 2H to 1H (or deuterium to hydrogen, or D/H, or ∂D where ∂ stands for difference) is considered a good indicator of temperature at the time of snow formation.
Hence changing hydrogen D/H ratios in the ice core chart changing temperature.
ice core layers and bubbles (past)
Ice accumulates in a sequence of annual increments.
Visible stratigraphy and chronology by counting the layers.
Air bubbles trapped in ice allow for direct measurement of past CO2 levels.
beryllium-10 (past)
Proxy for solar radiation.
More solar radiation creates more Be-10.
Similar process to that of C-14.
land-based weather stations (present)
Show surface of atmospheric data over land.
Data since mid 1800s.
Good coverage of land.
Reliable but subject to local effects.
Does not consider oceans or upper atmosphere.
buoys and floats (present)
Measure surface and/or deep water temperature and salinity.
Still somewhat less deep-water data.
satellites (present)
Solar output.
Ocean salt concentration.
Cloud thickness.
Sea surface temperature.
Ice sheet thickness.
Height of water in oceans.
climate models (future)
Global climate models divide the world into a grid, assign traits and properties to that grid, and run multiple simulations of the system.
Assumptions and limitations; dependent upon future human activity, some interactions are still not fully understood, and includes many random or semi-random processes.
Model validation; simulate models into the past, check for concordance between different designs, wait and see how short term predictions match actual data.
habitat fragmentation
Many times, natural habitats show a “patchy” distribution.
This affects the organisms that live there.
In todays world the effect of anthropogenic habitat fragmentation is probably much more significant.
Equally significant is the fact that many of the organisms in these habitats are not “adapted” for such fragmentation.
Activities such as “clearcutting” have created a mosaic of forested and un-forested areas in many regions that were once completely covered with forests.
effects of habitat fragmentation
With the growth of the human population and the increasing removal of natural habitat, the remaining wild areas begin to take form of “habitat islands” surrounded by relatively uninhabitable areas.
Habitat fragmentation is an increasingly serious problem in biological conversation.
The increasing significance of edge effects.
The remaining habitat begins to resemble an island, so the ideas of island biogeography theory are applied to them.
island biogography
On small islands, the number of species results primarily from the interaction of two processes; extinction and colonization.
The point at which these two rates are in equilibrium will determine the number of species found on the island.
In theory, the colonization rate will start high and decline, since there the initial number of species is low or none.
The extinction rate will start low (for the same reason) and rise until they reach equilibrium.
island theory applied to habitat fragmentation
If island formed from an area that was once part of a larger habitat, it will initially contain more species than the equilibrium of colonization can support.
Biotic relaxation = a decline in the number of species when a formerly “connected” region becomes isolated.
Can expect to lose species.
national parks
Habitat islands that show biotic relaxation.
Most pronounced in smaller parks.
Mount rainier national park in WA has seen reduction in number of mammals found there from 68 to 37 species.
metapopulation
Habitat fragmentation may create a meta-population, a group of subpopulations varying in size.
The smaller of these will tend to go extinct often (sink populations), and are only repopulated by individuals dispersing from larger subpopulations (source populations)
In such a situation the survival of the species in a region depends on the dynamics of the subpopulations.
If too many populations are small, and become sinks, then the whole population will move towards extinction.
conservation biology
Spatially explicity models combine population models with landscape maps to make mathematical predictions.
The creation of habitat patches from formerly continuous woodlands modifies the microclimate of the forest, resulting in increased edge effects.
Environmental conditions around edges are different from those in the interior.
This results in differences in the types of trees, the understory, and even the animals.
Ability of predators from open habitats to penetrate forest edges and prey on the animals there.
brown-headed cowbird
A nest parasite that frequents edge habitats.
A study in California looked at the number of chaparral bird species in isolated canyons in an urban setting. The number of bird species declined as the size of the canyon decreased.
Canyons visited by coyotes had more bird species than those that were not.
The coyotes apparently helped control the abundance of bird predators, like skunks and domestic cats.
fears for the future
Estimates are that the Mkomazi Game Reserve in Tanzania would lose 17 of its 39 species of large mammals in the next 300 years if it is separated from surrounding reserves.
Species-area curves can be used to predict how large a reserve must be to preserve its biological diversity.
For the Australian wheatbelt region, estimates are that a reserve of 43,000 hectares would be necessary to preserve all 25 species, and a reserve ¾ that large to preserve 90% of them.
The largest current preserve is 5119 hectares.
Based on work initiated by Terborgh, 5,000 square kilometers has been adopted as a rough minimum size for major tropical forest preserve in the Amazon Basin.
Based on very speculative reasoning, it is thought that this might reduce extinction rates to less than 1%
Near Manaus, Brazil, forest patches have been established: 1, 10, 100, 1,000, and 10,000 hectares.
Censused prior to isolation, and will be studied for at least 20 years.
Note 
Flashcard (175)