Ecology is derived from oikos (Greek) meaning ‘household’, and logos meaning ‘study’. Ernst Haeckel (1866): oecologie—the economy of nature.
What is ecology?– Numerous definitions; difficult to define;– The scientific study of how organisms interact with their environment;– Environment.
Ecology as a science• Started as largely observational and descriptive;• Natural history (study of how organisms are influenced by climate, soils, predators, competitors, and evolutionary history);• Now, ecologists primarily conduct experiments, test hypotheses, and develop models.
Ecology is a diverse science– Plant ecology;– Animal ecology;– Physiological ecology;– Population ecology;– Community ecology;– Ecosystem ecology;– Landscape ecology;– Applied ecology (problem solving);– Conservation ecology;– Restoration ecology.
Different types of ecology Organizme. In this part of ecology we deals with individuals, the lowest unit of ecology. How do they cope with difficult environments. How do they go from birth to death? i.e. their life history. How do they reproduce and how do they interact with their mates and offspring? Populations. Here we deal with groups of individuals of one species. In a certain population we might ask: ‘How many are old and how many are young? i.e. what is the structure of the population?’ Is the population growing, declining or in stasis? Species. On this level we are dealing with how the species interact with other species. So this level of ecology deals with competition and predation. Communities. Here we deal with all the species in a certain area. We might be interested in how many different types of species live in a certain place (diversity). Which species are the predators and which other species do they eat? i.e. food webs. Ecosystems . The concept of an ecosystem is similar to that of a community, in that we look at all the components biotic (living) and abiotic (non living) in a certain area. But what makes this type of ecology different is that all the components are studied using the same ‘currency’, and this is usually energy. So in ecosystem ecology you would try to find out where and how much energy was going from one component to another. An individual ecosystem is then distinguished from another by the fact that there would be little energy flow between them.
The Earth’s beginnings… The Earth is increadibely old. At first there were clouds of gas and dust called nebulae were scattered throughout the universe. Sun was forming as the dust cloud slowly condenses. Ssome sientists feel that meteorites once formed a small planet in our solar system that framented in space , while others view them simply as “leftover” material from theorginal nebula. Whatever the origin, they are materials from the beginnings of our solar system that have changed relatively little since their original formalion as rocks. Geologists use radioactive age dating methods to netermine the age of rocks. Certain atoms in the rocks spontaneously change into different atoms over time through radioactive decay. B taking a rock (meteorite)apart atom by atom and finding out how many atoms have decayed, and knowing the rate of change (or half-life of the atom) scietists can work out how many years have passed since the rock formed. This is a tremendous simplifacation, but basically it is somewhat like counting rings in a tree to see how old it is. Many meteorites age-date at about 4.6 billion years.This is the currently accepted age of the Earth.The early Earth was quite different from today with constant bombardment by meteorites, intense volcanism, and a poisonous atmosphere. However, fossils known as stromatolites in rock 3 to 3.5 billion years old show geologists that life evolved very early in the Earth’s history. During the time known as the Archean( 4 billion to 2.5 billion years ago) stomatolite fossils are very rare.Stomatolites are layered mounds, columns, and sheets found in the rock. They were originally formed by the growth of layer upon layer ofcyanobacteria, a single-celled photosynthesizing mikrobe growing on a sea floor. Cyanobacteria are prokariotic cells which lack a DNA-packaging nucleus. This simple organism would be the only life on Earth for the next 2 billion years.
Althought simple, cyanobacteria was ultimately responsible for one of the most importan “global chantes” that the Earth has undergone. Being photosynthetic, cyanobacteria produce oxygen as by-product. Photosynthesis is the only major source of free oxygen gas in the atmosphere. As stomatolites become more common 2.5 billion years ago, they gradually changed the Earth’satmosphere from a carbon dioxide-rich mixture to the present-day oxygen-rich atmosphere. This major change paved the way for the next evolutionary step, the appearance of life based on the eukaryotic cell.Rising out of the Ocean… They came from the oceans, where just a few billion years earlier the first animal life evolved followed by plants. So, you see, the occurrence of trees was quite full of twists and turns and came about quietly long after land plants had struggled to rise from the oceans. Yet, their existence is the essence of all life on the planet. There was a time about 550 million years ago when life “exploded” on the planet animal life. Nearly all of the animal groups in existence today – as well as many that no longer exist – first appeared on Earth during this time. It was the Cambrian Period, and this time of tumultuous and colossal animal diversity is called the Cambrian Explosion.Land plants evolved a little more quietly about 90 million years later, with trees evolving some 100 million years after the first land plants began to emerge from their oceanic origins. But neither animals nor plants could have evolved were it not for the protection and nurturing of the ocean. According to the fossil record – about 3.5 billion years ago – the first preserved life are found in the form of bacteria. They appeared in the oceans after the surface (crust) began to cool and stabilize, the land masses began to take shape, and clouds formed to produce massive volumes of rainwater that created the seas. The atmosphere was much different than today and the surface was unprotected from the Sun. This period is known as the Pre-Cambrian, the time that immediately followed the formative, molten and gaseous stage of Earth as it and the rest of the solar system started to come together – or coalesce. The first plants on Earth were a form of blue-green algae which appeared and lived in the oceans about 3.4 billion years ago according to the fossil record, protected from the harmful high energy radiation of the Sun. In the oceans, these plants were able to grow and photosynthesize as this high energy radiation was absorbed by the water. Now, to be perfectly clear about it, the first true algae (the kingdom protoctista) most likely made their first appearance about 2.4 billion years ago, but for sure by 1.8 billion years ago as the first acritarchs. Some 470 million years ago, Earth would seem lifeless, inhospitable and very barren. For one thing, no trees – no plants at all -lived on the land! Although animals were the first life forms on Earth, it was plants that paved the way for land animals to evolve. Plants did this by simultaneously increasing the percentage of oxygen in the Earth’s atmosphere and decreasing the percentage of carbon dioxide, a powerful greenhouse gas . Still, if we were to travel back about some 470 million years ago, Earth would seem lifeless, inhospitable and very barren. For one thing, no trees – o plants at all – ived on the land ! The first land plants made their appearance way before trees started driving their roots into the hard crust of Earth’s surface, about 460 million years ago in the Ordovician period. Algae were the first land plants, moving from their aquatic origins to marshy and wet environments on land. It took consistent growth and diversification of land plants — including the eventual evolution of trees – to help break up the mostly iron-clad surface of the Earth.
To move from the water to land, plants had to adapt systems that would support their weight, provide transport of water and nutrients throughout their system, protect them from drying out, and insulate them from the sun and temperature changes. Obviously, if these adaptations were not difficult, plants would have moved on to land much earlier in the geological history of the Earth. Instead, they appear rather late in the history of life on this planet. Trees first appeared and began to cover the land surface of the Earth some 370 million years ago. Today, we are so used to and dependent on trees that it’s hard to believe that animals could have existed without them or that they did not at least simultaneously evolve together in the beginning. Trees, with their large and thick roots, helped break up the rocky crust of Earth’s surface to create the soil that would allow the development of new plant species, including other trees. And it was the greater evolution of plants and trees that enabled the evolution of larger and more diverse land animals, including mammals. (Keep in mind that the first land animals – bugs – were plant eaters, and they required more and diverse vegetation to evolve.)The First Tree…and Forests The earliest known modern tree is the Archaeopteris, a tree that looked similar to a Christmas tree with buds, reinforced branch joints and wood similar to today’s timber. Its branches and leaves resembled a fern.When the archaeopteris tree first appeared 370 million years ago, it quickly covered most parts of the Earth with its first forests and was the dominant tree wherever the planet was habitable. During this time, most of Earth’s land masses were assembled south of the equator as part of the supercontinent Pangaea, which eventually split into the even continents that exist today. Can you imagine Antarctica being covered with forests! Over the past 370 million years, countless new tree species have evolved and eventually became extinct – like the archaeopteris – as the Earth’s land masses moved about, climates changed, animal populations increased, and, of course, new species of plants evolved to take the place of the extinct ones. Today there are approximately 100,000 known species of trees that exist throughout the world.Over 8,000 species are threatened with extinction and 976 of those are in a critical state.
The importan of Trees Trees are vitally important to world health on all levels. Globally, forests are essential to the health of ecosystems and their functions, biodiversity and economics. Some of the many key functions of forests include climate regulation, the cycling and distribution of nutrients, and the provision of raw materials and resources. Trees cleanse the air and provide oxygen, help soil retain water, shield animals and other plants from the sun and other elements, and provide habitat for animals and plants. They help regulate the climate, cycle and distribute nutrients and provide raw materials and other resources. And don’t forget the awesome beauty they give us throughout each year! While trees were once spread virtually across all of Earth’s land masses, today they cover about 3.9 billion hectares or just over 9.6 billion acres. One might think that’s a lot of trees! The fact is, trees now cover only about 29.6 percent of Earth’s total land area. But before we start blaming human greed, there is an important principle about ecology and how all species depend on other flora and fauna in order to evolve, grow and become healthy. For this to happen, some species must pass on in order that new species can live and evolve. Take the dinosaurs for instance. They died out some 65 million years ago – along with 70% of the total species on Earth at that time – which made room for the evolution of new species. Humans came along towards the end of this new evolutionary chain effect. Not to oversimplify the matter, but technically, if the dinosaurs had not died out, humans may not have evolved.
It’s All About Tradeoffs… Likewise, would humans have been able to make progress and perpetuate their species if forests continued to dominate Earth’s land areas? It is the enormous growth of the human species and the increasing needs and demands of the human population that have become critical factors in the forest cover equation and the perpetuation of many tree species today. The whole sustainability world is thinking about tradeoffs. What are we humans prepared to give up in order to have something else and still maintain the environmental goods and services we need? More of the natural environment will inevitably be lost. But, do we have to ruin so much, which is pretty much the way we are headed now? The question is, ‘Can we be smarter about development in the future?'” The process of natural selection for trees continues, but the advent of the Industrial Revolution created the foundation for exorbitant human demands of the land inhabited by trees. With the vast improvements in human health and technology, the human population would grow at a rate unparalleled by any other major land animal species in Earth’s 4.5 billion year history. And this would mean the demands for more resources from the Earth would increase exponentially. And so, humans have cleared forests primarily for their resources, to build cities and housing, and for agriculture. Industrialization has also been a significant contributor to the loss of our forest cover. When you consider that the world population has grown by more five billion people since the beginning of the Industrial Revolution, you can just imagine how much the world’s forests have been counted on to meet human needs! Approximately one billion people lived on the planet by 1800 – the early years of the Industrial Revolution. The population would rise to about 1.7 billion by 1900 and to 2.5 billion by 1950. Then the human population exploded! Over a period of 50 years, the population would increase 2.5 times to roughly 6.3 billion people today. From 1990 – 2000, about two percent of the world’s forest cover – roughly 10 million hectares – was lost and not recovered.That rate continues today. As it is today, the forests were mostly converted for agriculture, housing and city expansion (see urban sprawl) to meet the growing demands of the growing population. And therein lies the key to our dilemma! Certainly, stabilization of human population growth and wise use of resources are key to a majority of today’s ecological, public health and economical challenges. As the human population grows, sustainable development appears not only logical, but essential. According to American Forests, healthy cities should have an average tree canopy coverage of forty percent to ensure their ecological, economic and social sustainability. Rural areas should set a goal of at least fifty percent. But for many nations, the demand for resources from the forests are giving way to expansion and massive deforestation. When the human population growth has helped us realize the importance of trees. We do know that planting trees is one of the most cost-effective ways to capitalize on the natural services provided by healthy ecosystems. If the ‘sustainability world’ is smart about it, our forests will continue to evolve…quietly, and function, quietly, as guardians and vital instruments of Earth’s ecosystems. Yet – and unthinkably, if the last tree on Earth falls, it will fall quietly in much the same way the first tree evolved and once covered the planet.
Importance off water and its pollution Water is a unique substance. Most of our bodies and the bodies of all living things are made of water. All the chemical reactions needed to sustain life occur in water. Without it life here on earth as we know it would not exist, thus I am going to spend some time discussing it.
Structure. The molecular structure of water is 1 Oxygen molecule combined with 2 Hydrogen molecules – H2O. Hydrogen is the first element in the periodic table it has one proton and one electron. What does hydrogen need to be happy? (in terms of electrons) There are two things it needs, one to fill its electron orbital and two to have a neutral overall charge. Oxygen is 8 in the periodic table it has eight electrons. What does it need to be happy? The Hydrogen atoms join with a covalent bond which means that they share electrons not transfer electrons as in a ionic bond. Comprising over 70% of the Earth’s surface, water is undoubtedly the most precious natural resource that exists on our planet. Without the seemingly invaluable compound comprised of hydrogen and oxygen, life on Earth would be non-existent: it is essential for everything on our planet to grow and prosper. Although we as humans recognize this fact, we disregard it by polluting our rivers, lakes, and oceans. Subsequently, we are slowly but surely harming our planet to the point where organisms are dying at a very alarming rate. In addition to innocent organisms dying off, our drinking water has become greatly affected as is our ability to use water for recreational purposes. In order to combat water pollution, we must understand the problems and become part of the solution. Many causes of pollution including sewage and fertilizers contain nutrients such as nitrates and phosphates. In excess levels, nutrients over stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms consequently clogs our waterways, use up dissolved oxygen as they decompose, and block light to deeperwaters.This, in turn, proves very harmful to aquatic organisms as it affects the respiration ability or fish and other invertebrates that reside in water. Pollution is also caused when silt and other suspended solids, such as soil, washoff plowed fields, construction and logging sites, urban areas, and eroded river banks when it rains. Under natural conditions, lakes, rivers, and other water bodies undergo Eutrophication, an aging process that slowly fills in the water body with sediment and organic matter. When these sediments enter various bodies of water, fish respirationbecomes impaired, plant productivity and water depth become reduced, and aquatic organisms and their environments become suffocated. Pollution in the form of organic material enters waterways in many different forms as sewage, as leaves and grass clippings, or as runoff from livestock feedlots and pastures. When natural bacteria and protozoan in the water break down this organic material, they begin to use up the oxygen dissolved in the water. Many types of fish and bottom-dwelling animals cannot survive when levels of dissolved oxygen drop below two to five parts per million. When this occurs, it kills aquatic organisms in large numbers which leads to disruptions in the food chain. Pathogens are another type of pollution that prove very harmful. They can cause many illnesses that range from typhoid and dysentery to minor respiratory and skin diseases. Pathogens include such organisms as bacteria, viruses, and protozoan. These pollutants enter waterways through untreated sewage, storm drains, septic tanks, runoff from farms, and particularly boats that dump sewage. Though microscopic, these pollutants have a tremendous effect evidenced by their ability to cause sickness. Three last forms of water pollution exist in the forms of petroleum, radioactive substances, and heat. Petroleum often pollutes waterbodies in the form of oil, resulting from oil spills water . These large-scale accidental discharges of petroleum are an important cause of pollution along shore lines. Besides the supertankers, off-shore drilling operations contribute a large share of pollution. One estimate is that one ton of oil is spilled for every million tons of oil transported. This is equal to about 0.0001 percent. Radioactive substances are produced in the form of waste from nuclear power plants, and from the industrial, medical, and scientific use of radioactive materials. Specific forms of waste are uranium and thorium mining and refining. The last form of water pollution is heat. Heat is a pollutant because increased temperatures result in the deaths of many aquatic organisms. These decreases in temperatures are caused when a discharge of cooling water by factories and power plants occurs.Classifying water pollution The major sources of water pollution can be classified as municipal, industrial, and agricultural. Municipal water pollution consists of waste water from homes and commercial establishments. For many years, the main goal of treating municipal wastewater was simply to reduce its content of suspended solids, oxygen-demanding materials, dissolved inorganic compounds, and harmful bacteria. In recent years, however, more stress has been placed on improving means of disposal of the solid residues from the municipal treatment processes. The basic methods of treating municipal wastewater fall into three stages: primary treatment, including grit removal, screening, grinding, and sedimentation; secondary treatment, which entails oxidation of dissolved organic matter by means of using biologically active sludge, which is then filtered off; and tertiary treatment, in which advanced biological methods of nitrogen removal and chemical and physical methods such as granular filtration and activated carbon absorption are employed. The handling and disposal of solid residues can account for 25 to 50 percent of the capital and operational costs of a treatment plant. The characteristics of industrial waste waters can differ considerably both within and among industries. The impact of industrial discharges depends not only on their collective characteristics, such as biochemical oxygen demand and the amount of suspended solids, but also on their content of specific inorganic and organic substances. Three options are available in controlling industrial wastewater. Control can take place at the point of generation in the plant; wastewater can be pretreated for discharge to municipal treatment sources; or wastewater can be treated completely at the plant and either reused or discharged directly into receiving waters. Agriculture, including commercial livestock and poultry farming, is the source of many organic and inorganic pollutants in surface waters and groundwater. These contaminants include both sediment from erosion cropland and compounds of phosphorus and nitrogen that partly originate in animal wastes and commercial fertilizers. Animal wastes are high in oxygen demanding material, nitrogen and phosphorus, and they often harbor pathogenic organisms. Wastes from commercial feeders are contained and disposed of on land; their main threat to natural waters, therefore, is from runoff and leaching. Control may involve settling basins for liquids, limited biological treatment in aerobic or anaerobic lagoons, and a variety of other methods.
Importan of air and its pollution How many of us realize that this has become irrelevant in today’s world, because the quality of air in our cities is anything but fresh. Air pollution is aggravated because of four developments: increasing traffic, growing cities, rapid economic development, and industrialization. The Industrial Revolution in Europe in the 19th century saw the beginning of air pollution as we know it today, which has gradually become a global problem. One of the formal definitions of air pollution is as follows – ‘The presence in the atmosphere of one or more contaminants in such quality and for such duration as is injurious, or tends to be injurious, to human health or welfare, animal or plant life.’ It is the contamination of air by the discharge of harmful substances. Air pollution can cause health problems and it can also damage the environment and property. It has caused thinning of the protective ozone layer of the atmosphere, which is leading to climate change.
Modernisation and progress have led to air getting more and more polluted over the years. Industries, vehicles, increase in the population, and urbanization are some of the major factors responsible for air pollution. The following industries are among those that emit a great deal of pollutants into the air: thermal power plants, cement, steel, refineries, petro chemicals, and mines. Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest fires and grass fires contribute to chemical and particulate pollution of the air. The source of pollution may be in one country but the impact of pollution may be felt elsewhere. The discovery of pesticides in Antarctica, where they have never been used, suggests the extent to which aerial transport can carry pollutants from one place to another. Probably the most important natural source of air pollution is volcanic activity, which at times pours great amounts of ash and toxic fumes into the atmosphere. The eruptions of such volcanoes as Krakatoa in Indonesia, Mt. St. Helens in Washington, USA and Katmai in Alaska, USA, have been related to measurable climatic changes.
Listed below are the major air pollutants and their sources Carbon monoxide (CO) is a colourless, odourless gas that is produced by the incomplete burning of carbon-based fuels including petrol, diesel, and wood. It is also produced from the combustion of natural and synthetic products such as cigarettes. It lowers the amount of oxygen that enters our blood . It can slow our reflexes and make us confused and sleepy. Carbon dioxide (CO2)is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases. Chloroflorocarbons (CFC) are gases that are released mainly from air-conditioning systems and refrigeration. When released into the air, CFCs rise to the stratosphere, where they come in contact with few other gases, which leads to a reduction of the ozone layer that protects the earth from the harmful ultraviolet rays of the sun. Lead is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer. Ozone occur naturally in the upper layers of the atmosphere. This important gas shields the earth from the harmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, burn, and water. It lowers our resistance to colds and pneumonia. Nitrogen oxide (Nox) causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxides can make children susceptible to respiratory diseases in winters. Suspended particulate matter (SPM) consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems. Sulphur dioxide (SO2) is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. It is a major contributor to smog and acid rain. Sulfur dioxide can lead to lung diseases.
Health impact of specific air pollutants Some of these gases can seriously and adversely affect the health of the population and should be given due attention by the concerned authority. The gases mentioned below are mainly outdoor air pollutants but some of them can and do occur indoor depending on the source and the circumstances. Tobacco smoke. Tobacco smoke generates a wide range of harmful chemicals and is a major cause of ill health, as it is known to cause cancer, not only to the smoker but affecting passive smokers too. It is well-known that smoking affects the passive smoker (the person who is in the vicinity of a smoker and is not himself/herself a smoker) ranging from burning sensation in the eyes or nose, and throat irritation, to cancer, bronchitis, severe asthma, and a decrease in lung function. Biological pollutants. These are mostly allergens that can cause asthma, hay fever, and other allergic diseases. Volatile organic compounds. Volatile compounds can cause irritation of the eye, nose and throat. In severe cases there may be headaches, nausea, and loss of coordination. In the longer run, some of them are suspected to cause damage to the liver and other parts of the body. Formaldehyde. Exposure causes irritation to the eyes, nose and may cause allergies in some people. Lead. Prolonged exposure can cause damage to the nervous system, digestive problems, and in some cases cause cancer. It is especially hazardous to small children.
Radon. A radioactive gas that can accumulate inside the house, it originates from the rocks and soil under the house and its level is dominated by the outdoor air and also to some extent the other gases being emitted indoors. Exposure to this gas increases the risk of lung cancer. Ozone. Exposure to this gas makes our eyes itch, burn, and water and it has also been associated with increase in respiratory disorders such as asthma. It lowers our resistance to colds and pneumonia. Oxides of nitrogen. This gas can make children susceptible to respiratory diseases in the winters. Carbon monoxide. CO (carbon monoxide) combines with haemoglobin to lessen the amount of oxygen that enters our blood through our lungs. The binding with other haeme proteins causes changes in the function of the affected organs such as the brain and the cardiovascular system, and also the developing foetus. It can impair our concentration, slow our reflexes, and make us confused and sleepy. Sulphur dioxide. SO2 (sulphur dioxide) in the air is caused due to the rise in combustion of fossil fuels. It can oxidize and form sulphuric acid mist. SO2 in the air leads to diseases of the lung and other lung disorders such as wheezing and shortness of breath. Long-term effects are more difficult to ascertain as SO2 exposure is often combined with that of SPM. SPM (suspended particulate matter). Suspended matter consists of dust, fumes, mist and smoke. The main chemical component of SPM that is of major concern is lead, others being nickel, arsenic, and those present in diesel exhaust. These particles when breathed in, lodge in our lung tissues and cause lung damage and respiratory problems. The importance of SPM as a major pollutant needs special emphasis as a) it affects more people globally than any other pollutant on a continuing basis; b) there is more monitoring data available on this than any other pollutant; and c) more epidemiological evidence has been collected on the exposure to this than to any other pollutant.Important of soil and its pollution Soil is the thin layer of organic and inorganic materials that covers the Earth’s rocky surface. The organic portion, which is derived from the decayed remains of plants and animals, is concentrated in the dark uppermost “topsoil.” The inorganic portion, which is made up of rock fragments, was formed over thousands of years by physical and chemical weathering of bedrock. 1) Soil Erosion occurs when the weathered soil particles are dislodged and carried away by wind or water. Temperature extremes, precipitation including acid rain, and human activities contribute to this erosion. Soil scientists have estimated that already about one third of the original topsoil has been blown away or washed into rivers or lakes. Humans speed up this process by construction, mining, clear cutting of timber, agricultural development and overgrazing. 2) Soil nutrients are important for plant growth and development. Plants obtain carbon, hydrogen, and oxygen from air and water but other necessary nutrients like nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and more must be obtained from the soil. Farmers generaly use fertilizers to correct soil deficiencies. Mixed fertilizers often contain ammonium nitrate (NH4NO3), phosphorus as P2O5, and potassium as K2O. Fertilizer runoff leads to the eutrophication of waterways, as mentioned in the Water Pollution part. 3) Pesticides, insecticides and herbicides are used by farmers to kill unwanted populations living in or on their crops. Plants on which we depend for food are under attack from insects, fungi, bacteria viruses, rodents and other animals, and must compete with weeds for nutrients. The first widespread insecticide use began at the end of World War II and included DDT (dichlorodiphenyltrichoroethane). It seemed ideal, but insects soon became resistant to it and the chemical did not decompose readily, but persisted in the environment. Since it was soluble in fat rather than water, it biomagnified up the food chain and disrupted calcium metabolism in birds causing eggshells to be thin and fragile. As a result, large birds of prey such as ospreys, falcons and eagles became endangered. DDT was banned in 1972. An infamous herbicide also eventually banned in 1985 was Agent Orange (dioxin), used as a defoliant in the Vietnam War. Soldiers’ cancer rates, skin conditions and infertility have been linked to exposure to Agent Orange. Pesticide problems such as resistance, resurgence, and heath effects have caused scientists to seek alternatives. Can you think of other ways to control insects? Pheromones and hormones to attract or repel insects and using natural enemies or sterilization by radiation have been suggested.
4) Solid waste disposal was brought to the forefront of public attention long time ago. Toxic chemicals leached from oozing storage drums into the soil underneath homes causing an unusually large number of birth defects, cancers and respiratory, nervous and kidney diseases. In general, solid waste includes garbage, refuse and sludge from homes and industries. Most agricultural waste is recycled and mining waste is left on site. Municipal waste from homes, institutions and commercial establishments is either incinerated (see Air Pollution) or placed in a sanitary landfill. Since urban solid waste tends to be 41% paper and 21% food waste, the majority is recyclable or biodegradable. It is the portion that is hazardous such as oils, battery metals and organic solvents that we have to pay particular attention to since these can contaminate or sole source drinking water. More than 90% of hazardous waste is produced by chemical, petroleum and metal-related industries and small businesses such as dry cleaners and gas stations contribute as well. To help prevent soil erosion, we can limit construction in sensitive area. In general we would need less fertilizer and fewer pesticides if we could all adopt the three R’s: Reduce, Reuse, and Recycle. This would give us less solid waste. Industrial wastes can be treated physically, chemically and biologically until they are less hazardous. As a last resort, new areas for storage are being investigated such as deep well injection and more secure landfills.Conclusion: All these problems have huge influance to all organisms living on the Earch so there are pollution prevention programs in all countrys what to stop such air , water and soil pollution ,and to save disappering spieces of wild world. For ecology it is the most importan things.Finally enviroment plays a large role in every human’s life.Frequently we just don’t pay attention to all bad things we do to nature and for salves.Unfortunately,pollution levels are increasing at an alarming rate and we should do everything as well as we can to reduce it.There is in Lithuania the Ecology Building Sociaty and it is a unique lending institution established to provide mortgage for properties which give an ecological payback. We must look at enviroment protection laws and norm system creating.It is importan to fight with results of pollution and other bad things but with reasons which let to progress reasons why everything is happning.And it is not even ecologists deal but all people deal.It is very important and economical help,which intetion – promote polluters minify number of pollutants , instil pollution prevention implements, treasure our natural resources. Economical help – it is pay of pollution, users pay, reduction of pay, subsidy or credits, pay of getting order. It is very importan role of society education and conveyance. Today there is deficit of education material what to organize ecological education and sodiety is not very interested what is happning around them,even where pollution have proximate and huge influance to people health.In future it wouldn’t be.Today in Lithuania everything turn to economical problems, and lows default. But there are clubs of group people who care ecccology and people and all living organisms life. And we must by thankful for them.