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The study of the interactions among organisms and their

interrelationships with the physicalenvironment. No organism exists as an entity, separate and distinct

from its environment

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Components of the ecosystem involve interacting abiotic factors and biotic

factors.

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The abiotic environment includes physical and chemical factors which affect the ability of

organisms to live and reproduce.

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- Intensity of light- Range of temperatures - Amount of moisture- Type of substratum- Availability of inorganic substances such as minerals- Supply of gases such as O2, CO2, N2.- pH

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Each of these factors varies in the environment and, as such, may act as a limiting factor,determining the types of organisms

which may exist in that environment.

Examples include:- A low annual temperature common to the northern

latitudes determines determines in part whatspecies of plants can exist in that area.

- The amount of oxygen dissolved in a body of water will help determine which species of fish will exist

there.- The salt-laden air and water of coastal areas limit

what species can exist in those regions.

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Biotic Factors are all the living things that directly, or indirectly affect the environment. Thus, the organisms, their presence, parts,

interaction, and wastes, all act as biotic factors.

Biotic Factors interact in many ways such as in nutritional relationships and symbolic

relationships.

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A population is all the members of a species

inhabiting a givenlocation

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All the interacting populations in a given area represent

a community

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An ecosystem is the living communityand the physical environment functioning

together as an interdependent and relativelystable system.

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The biosphere is the portion of the earth in which life exists. It is composed of

numerous complex ecosystems.

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A major regional or global biotic community, such as a grassland or desert, characterized

chiefly by the dominant forms of plant life and the prevailing climate.

Biomes may be terrestrial or aquatic. The temperate deciduous forest of the northeastern

United States is a terrestrial biome. The ocean is an aquatic biome.

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The major plant and animal associations on land are determined by the major climate zones of the

world, modified by local land and water conditions.

Climates will vary as to temperature, solar radiation, and precipitation. The presence or absence of water is a major limiting factor for

terrestrial biomes.

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Land biomes are characterized and sometimes named by the climax

vegetation in the region. The major land biomes, and their characteristics, flora, and fauna are listed on the next

pages.

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Characteristics: permanently frozen subsoilClimax Flora: Lichens, mosses, grassesClimax Fauns: Caribou, Snowy Owl

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Characteristics: long, severe winters; summers with thawing subsoil.Climax Flora: conifersClimax Fauna: moose & black bear

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Characteristics: moderate precipitation; cold winters, warm summers Climax Flora: trees that shed leaves (deciduous trees)Climax Fauna: gray squirrel, fox & deer

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Characteristics: heavy rainfall; constant warmth

Climax Flora: many species of broad-leafed plantsClimax Fauna: snake, monkey,

leopard

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Characteristics: considerable variability in rainfall and temperature; strong prevailing windsClimax Flora: grassesClimax Fauna: pronghorn antelope, prairie

dog & bison

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Characteristics: sparse rainfall;extreme daily temperature fluctuationsClimax Flora: drought-resistant shrubs and succulent plantsClimax Fauna: kangaroo rat & lizard

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Climatic conditions change with latitude and altitude.

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The largest part of the biosphere (the earth) is made up of aquatic biomes. It was here that life first arose, and here it evolved for almost three billion years, before plants and animals moved onto land. There are two main types of

Aquatic Biomes: Freshwater and Marine. Freshwater biomes usually have a salt concentration of less than 1%, whereas

Marine biomes have a salt concentration that averages 3%.

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Freshwater Aquatic Biomes have close ties to their surrounding terrestrial biomes. Runoff of water from land creates streams and rivers, and where runoff in

trapped, ponds and lakes are formed. Also, the characteristics of a freshwater biome are influenced by

the pattern and speed of water flow, as well as the climate to which the biome is exposed.

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Marine Aquatic Biomes are found in the Earth’s oceans, covering nearly 75% of the Earth’s surface.

Most of the planet’s rainfall is from the evaporation of the Earth’s oceans, and the

temperatures of the oceans strongly effect the world’s climate and wind patterns. Marine Algae are a major source of oxygen for the world, as well

as consuming huge amounts of carbon dioxide from the atmosphere.

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The ecosystem is the structural and functional unit studied in ecology.

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An ecosystem involves interactions between abiotic and biotic factors. An ecosystem is a

self-sustaining unit if the following requirements are met:

- A constant source of energy and a living systemcapable of incorporating this energy into organic

compounds.- A cycling of materials between organisms

and their environment.

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Nutritional Relationships involve the transfer of nutrients from

one organism to another within an ecosystem.

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These organisms can synthesizetheir own food from

inorganic compounds and an unable energy source.

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These organisms cannot synthesize their own food and are dependent upon other organisms for food. On the basis of this

dependency, organisms are classified as either saprophytes, herbivores, carnivores, or omnivores.

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- include those heterotrophic plants, fungi, and

bacteria which live on dead matter.

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- are those animals which consume plants

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- are those animals which consume other animals.

These include:- PREDATORS ---- animals which kill and consume their

prey.

- SCAVENGERS ---- animals which feed on other animals

which they did not kill.

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- are those animals which consume both plants and

animals.

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Different organisms may live together in a closeassociation. This living together in a close

association is known as symbiosis. Symbiosis relationships may or may not be beneficial to the

organisms involved.

Symbiotic Relationships may include: Nutritional. Reproductive, and protective

relationships.

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In this relationship one organism is benefited and the other is not adversely affected. Example: Barnacles & Whales

In this relationship both organisms benefitfrom this association.Example: Nitrogen-fixing bacteria within the nodules of legumes & certain protozoa within termites.

In this relationship, the parasite benefits at the expense of the host.Example: Tapeworm and heart worm in dogs.

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If an ecosystem is to be self-sustaining it must contain a flow of energy

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Those life activities which are characteristics of living organisms require the expenditure of energy

The pathways of energy through living components of an ecosystem are represented by food chains and food webs.

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Green plants convert radiant energy from the sun into chemical energy (food). A food chain involves the

transfer of energy from green plants through a series of organisms with repeated stages of eating and being

eaten.

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In a natural community, the flow of energy and materials is much more complicated than is illustrated by any one food chain. Since practicallyall organisms may be consumed by more than one species, many interactions occur among the food chains of any community. These interactions are described as a food web.

Interactions in a food web involve:

1) Producers

2) Consumers

3) Decomposers

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GrasseGrasses s

shrubs shrubs

rabbitrabbitss

coyotescoyotes

insectinsectss

spiderspiderss

frogfrogss

Seed-Seed-eating eating birdsbirds

hawkhawkss

RatRatss

licelice

snakesnakess

DeerDeer

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The energy from a community is derived from the organic compounds synthesized by

green plants. Autotrophs are therefore considered the

producers.

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Organisms that feed directly upon green plants are primary consumers or herbivores. Secondary consumers, or carnivores, feed upon other consumers.

Omnivores may be either primary or secondary consumers.

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Organic wastes and dead organisms are eventually broken down to simpler substances by decomposers, such as the bacteria of decay. Through this action, chemical

substances are returned to the environment where they can be used by other living organisms.

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Energy flows through ecosystems from producers to various levels of consumers. Each time an organism eats one another, not all of the energy is transferred.

Only about 10% of energy of a producer is transferred to the consumer who eats it. Therefore, there is a

progressive loss of energy at each level of the food chain. We can represent each amount of energy at

each level as a part of a pyramid.

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It is possible to estimate the mass of all the organisms living in a given area or ecosystem. The estimation is known as the bio mass. If the

mass of the producers and each type of consumer is recorded, a pyramid can be constructed showing the bio mass of the

producers is far greater then the bio mass of the consumers.

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In a self-sustaining ecosystem, material must be cycled among the organisms and the abiotic environment. Therefore, the

same materials can be reused.

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The Water Cycle involves the processes of photosynthesis, transpiration, evaporation

and condensation, respiration, and excretion.

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EVAPORATION - The first stage of the water cycle is evaporation. As water is heated by the sun, its surface molecules become energized to break free of the attractive force binding them together. They then rise as an invisible vapor into the atmosphere.

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CONDENSATIONAs water vapor rises, it cools and eventually condenses, usually as tinyparticles of dust in the air. When it condenses, it becomes a liquid again or turn directly into solid ( ice, hail or snow). These water particles thencollect and form clouds.

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When the clouds are too heavy, they fall as rain.

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Is the the continuous flow of nitrogen through the biosphere by the processes of

nitrogen fixation, ammonification (decay) nitrification, and denitrification. Nitrogen is

vital to all living matter, both plant and animal; it is an essential constituent of amino acids, which form proteins of nucleic acids, and of

many other organic materials.

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Ecosystems tend to change over time until a stable system is formed. The type of ecosystem that is formed depends on the climatic limitations of a

particular geographical area.

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Succession may be defined as a continuous unidirectional, sequential change in species

composition of natural communities.

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The sequence from grass to shrub to forest that terminates in a relatively stable community historically has been called a sere and each of the changes a seral stage. Although seral stage is a point on a continuum of vegetation through time, it is recognizable as a distinct community. Each has itscharacteristic structure and species composition. A seral stage may last only one or two years or may last for decades. Eventually, succession slows and the plant community achieves some degree of equilibrium or steady state with the environment. This mature, relatively self-sustaining seral stagetraditionally been called the climax.

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Succession that begins on areas unoccupied or unchanged by organisms is called primary succession. Succession that proceeds on areas where other organisms were present is called secondary succession. Barren areas, whether they are natural primary sites, such as rock outcrops, sand dunes, and alluvial deposits, such as abandoned cultivated fields or road banks, are a natural vacuum eventually filled by living organisms. Organisms that colonize such sites comprise thepioneer species. Succession that is self-driven or autogenic when changes in the environment are brought about by organisms themselves. In other cases changes in the environment are caused by some external factor unaffected by the organisms is termed allegoric.

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Succession may be said to begin with pioneer organisms, since these are the first plants to

populate a given location.

Some examples are: Lichens, they are the pioneer organisms on bare rock.

Pioneer organisms modify their environment. Seasonal die back and erosion, for example, would create pockets of “soil” in the crevices and hollows

on the bare rock.

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Each community modifies the environment, often making it more unfavorable for itself and, apparently, more favorable for the following community which infiltrates the first community over a period of years.

A typical successional sequence in New York State might be: pioneer, grass, shrub, conifer, and deciduous woodland.

Plant species (flora) dominate in the sense that they are most abundant food sources. Plant succession is a major limiting factor for animal (fauna) succession.

Communities are composed of populations able to exist under the prevailing conditions and are identified by their dominant plant species-- the one that exerts the most influence over the other species present.

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A climax community is one that has reached the stable stage. When extensive and well defined, the climax community is

called a biome. Examples are tundra, grassland, desert, and the deciduous, coniferous, and tropical rain forests. Stability is attained through a process known as succession, whereby

relatively simple communities are replaced by thosemore complex. Thus, on a lakefront, grass may invade a build-up of sand. Humus formed by the grass then gives root to oaks and pines and lesser vegetation, which displaces the grass and forms a further altered humus. That soil eventually nourishes maple and beech trees, which gradually crowd out the pines and oaks

and form a climax community. In addition to trees, each successive community harbors many other life forms, with the

greatest diversity populating the climax community.

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Similar ecological zonings occur among marine flora and fauna, dependent on such environmental factors as bottom composition,

availability of light, and degree of salinity. In other respects, the capture by aquatic plants of solar energy and inorganic materials, as well as their transfer through food chains and cycling by means of microorganisms, parallels those processes on land. The early 20th-century belief that the

climax community could endure indefinitely is now rejected because climatic stability cannot be assumed over long periods of time. In

addition nonclimatic factors, such as soil limitation, can influence the rate of development. It is clear that stable climax communities in most

areas can coexist with human pressures on the ecosystem, such as deforestation, grazing, and urbanization. Polyclimax theories stress that

plant development does not follow predictable outlines and that the evolution of ecosystems is subject to many variables.

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Competition occurs when different species or organisms living in the same environment (habitat) utilize the same limited resources, such as food, space, water, light, oxygen, and

minerals.

The more similar the requirements of the organisms involved, the more intense the competition.

If two different species compete for the same food or reproductive sites, one species may be eliminated. This

usually establishes one species per niche in a community. The niche is the organisms role in the community.

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Humans, in exercising a unique and powerful influence on the physical and living world, have

modified their environment.

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Natural systems have been upset because humans have not realized that they not only influence other individuals, other

species, and their nonliving world, but are, in turn, influenced by them.

Although most ecosystems are capable of recovering from impact of minor disruptions, human activities have sometimes

increased the magnitude of such disruptions so as to bring about a more lasting and less desirable change in the

environment upon which all life depends.Such disruptions will directly affect at least one of the

components of an ecosystem and this, in turn, may affect the remaining.

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Many of us have seen linear graphs of human population showing the enormous growth in the last two centuries.

However, significant changes in population dynamics are lost in the exponential growth and long time scales. If the data are

replotted on a log-population by log-time scale, significant population dynamics emerge. First, it is apparent that

population growth has occurred in three surges and second, that the time between surges has dramatically shortened.

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Some human activities have led to led to the extinction or endangerment of numerous species of plants and animals as well as producing less favorable living conditions for many species, including humans. Such activities include: 1) Over hunting

2) Importation of Organisms3) Exploitation4) Poor Land Use Management5) Technological Oversight

a) water pollutionb) Air pollutionc) Biocide Used) Disposal Problems

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Uncontrolled hunting, trapping, and fishing still occur in many parts of the world. The extinction of the Dodo Bird and the Passenger Pigeon resulted from such activities. Endangered

species include the blue whale.

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Humans have accidentally and/or intentionally imported organisms to areas where they have no

natural enemies leading to the disruption of existing ecosystems. Examples include: the Japanese beetle, Gypsy Moth and disease-causing organisms such as

those that cause Dutch Elm Disease.

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The exploitation of wildlife, both flora and fauna, for their products and their pet trade has to led threatened populations

and ecosystem disruptions.

Examples include: the African Elephant and the Pacific Walrus -- ivory; the Colombian parrot -- pet trade; Tropical

Rainforest -- plywood.

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Increased urbanization /sub-urbanization claims increasing amounts of agricultural lands; modifies

watersheds, disrupts natural habitats (including wetlands), and threatens the existence of the wildlife

species.

Poor Land use management practices have led to to over cropping, overgrazing and failure to use cover crops. This has resulted in the loss of valuable soil

nutrients.

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Major water pollutants include:

heat, sewage, and chemicals such

as phosphates, heavy metals,

and PCB’s.

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PCB’s or Polychlorinated Biphenyl’s are a class of chlorinated compounds. They are a group of chlorinate hydrocarbons that are manufactured by the controlled chlorine

substitution of the biphenyl molecule. They mainly exist in two states – the form of asolid and in a liquid. In a solid state at 15 degrees Celsius it is a white powder and in a liquid state it is an oily liquid with a pale yellow coloring. The structure consists of two

atomic rings that are 6 membered and have varying degrees of chlorinating oneach ring.

Generally, PCB’s are non reactive, very stable compounds that exist in our environment. They were first used in industrial applications in 1929 due to their unique chemical stability, thermal stability, high dielectric constant, non flammability and their

low cost. They are used in paints, printing inks, carbonless copy paper, sealants, and adhesives. They are also used to insulate fluids in electrical transformers and capacitors in the power industry, heat transfer substances, cutting oils, hydraulic fluids, lubricating oils and plasticizers for making brittle plastic pliable. PCB’s usually enter our aquatic

ecosystems via precipitation, industrial discharges and agricultural runoff.

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For many years PCB’s have been used for industrial purposes. Concern about the impact on the environment and human health did not arise to a noticeable height until 1966. Due to their unique chemical stability and their resistance to chemical oxidation, photodegradation, thermal changes, most chemical agents, acid-base reactions and hydrolysis they are very poorly metabolized by biological systems. Also they are extremely soluble in oils and fat and yet in water their solubility is

very poor and varies inversely to the degree of chlorinating. More heavily chlorinated congeners have a higher likelihood of undergoing absorption to the surface of a soil particle. This is then followed by a slower diffusion into the soil. The lower the organic content the faster this absorption takes place. With this

activity of absorption into the soil PCB’s are barely detectable in surface waters with low particulate loads. However, they may exist in high concentrations in the bottom sediments. They partition out of the aquatic ecosystem and into biologic

tissue. As a result of their persistence and poor rate of metabolization this substance accumulates in the food chain and increases in concentration at each

level of consumption and can build up from 10 million times. Through inhalation, ingestion and dermal contact PCB’s can be easily absorbed by most animals.

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Affects due to exposure can range from acute to chronic. Slight exposure to the vapor may irritate eyes, nose and throat, high exposure could result in damage to the liver. Chronic (long term heath affects) can occur some time after exposure and may last for months or years. In animals they have been shown to be teratogens. So it is likely that they may be teratogens in humans thus being hazardous to reproduction. They may be passed from

mother to child and can affect adult reproductive systems. Another concern is that PCB’s are probable carcinogens in humans. There is possible evidence that they cause skin cancer in humans and liver cancer in animals. Other possible affects are a severe rash similar to acne that lasts for many years. High exposure may also result in damage to the nervous

system causing "pins and needles" in the arms and legs. PCB’s can however be partially dechlorinated in anaerobic environments. With the

addition of hydrogen peroxide to the aqueous system bioremediation processes can be accelerated and expedite PCB removal. In the 1970’s the production of PCB’s was

stopped, however, many still exist and continue to pose a threat to our environment despite strict regulations and efforts to make the public aware of the hazards of PCB’s. Further

development through research to discover effective techniques to remove these compounds from our environment and remove the hazards to ourselves and our wildlife are vital.

Hopefully, one day we will finally be able to generate lasting solutions and to put an end to the problem of hazardous

waste.

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Major air pollutants include: carbon monoxide, hydrocarbons, and particulates. Nitrogen oxides and sulfur dioxide combine

with water vapor creating acid rain problems. On the next page you will find information on acid rain.

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"Acid rain" is a general name for many phenomena including acid fog, acid sleet, and acid snow. Although we associate the acid threat with rainy days, acid deposition occurs all the time, even on sunny days. Something is acidic if it has a low pH. The pH

of a liquid is measured on a scale which ranges from 0 to 14 with 7.0 being neutral. Anything with a pH value lower than 7.0 is acidic, and

anything higher than 7.0 is basic. (For more information see the chart on pH.) Particles of sulfur and nitrogen emitted by cars, coal-

fired generators, and non-ferrous smelters can be carried great distances and deposited anywhere from a few hundred to a few

thousand kilometers from their source area. Even when sulfur and nitrogen particles fall to the surface as dry deposition they combine with water at the earth's surface or in the ground to produce the

same effects as wet deposition.

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The use of some biocides (such as pesticides and herbicides) without a complete assessment of their environmental impact has contaminated the soil, atmosphere, water supply, and has disrupted food webs. Examples include: DDT effects on the Bald

Eagle and Peregrine Falcon.

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The affluent lifestyle of humans currently requires increasing supplies of products and energy, the

production of which produces considerable wastes: solid, chemical, and nuclear

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Through increased awareness of ecological interactions humans have attempted to prevent continued disruption of the environment and to

counteract the results of many of our past negative practices.

A. POPULATION CONTROL: methods of controlling the human reproductive rate has been, and will continue to be, developed.

B. CONSERVATION OF RESOURCES: Soil cover plantings (reforestation and cover cropping) serve as erosion occurs. Water and

energy conserving measures are currently being implemented. The economic significance of recycling is now being realized.

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C. Pollution Control - Attempts are being made to control air and water pollution by laws and by the development of new techniques of sanitation.

D. Species Preservation - Some efforts to sustain endangered species have included habitat protection (wildlife refuges and natural parks) and wildlife management (game laws and fisheries). Animals which were once endangered but are presently successfully reproducing and increasing their numbers are bison and egrets. Endangered animals which are currently responding to conservation efforts and beginning to make a comeback are the whooping crane, bald eagle, and peregrine falcon. The future of some species are still in doubt.

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E. Biological Control - Biological control of insect pests continues to be encouraged. This method is less likely to:

1. Affect those species which are beneficial to humans

2. Disrupt food webs

3. Contaminate the land

The use of sex hormones and natural parasites are an example.

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There are laws which regulate and guide the use of natural habitats.

SEQR -- A New York State Law designed to provide the opportunity for citizen review and comment of the environment impact of any proposed development that has been determined to have significant effect on the

environment.

FRESHWATER WETLANDS ACT -- A New York State Law designed to regulate the use of large or unique freshwater wetlands both publicly and privately owned so as to prevent their destruction and thus maintain

valuable wetlands for all life forms.

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While human technological advances have led to a higher standard of living for many, the environment has often suffered. Through a greater awareness of

ecological principles, wise use of our energy resources, and concern for future generations not only of humans, but also of all species, each individual can help to

assure that there will be suitable environments for succeeding generation.

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The