Introduction to Environmental Science (SES-301) Notes PDF

DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-2, 3 An overview of Environmental Science Environmental Science Environmental science...

DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-2, 3 An overview of Environmental Science Environmental Science Environmental science is the field of science that studies the interactions of the physical, chemical, and biological components of the environment and also the relationships and effects of these components with the organisms in the environment. It is the scientific study of the dynamic relationships and processes that occur among the biological and physical components of nature and their impact on economic and social systems at multiple spatial and temporal scales. Environmental science is, by its nature, an interdisciplinary area of study, because it incorporates information and ideas from multiple disciplines. Concepts and principles of subjects such as mathematics, physics, biology, chemistry, geology, social sciences, humanities, geography, economics, political science, philosophy and ethics etc. are extensively used to study environmental science. It is important for students of environmental science to recognize that environmental science is different from environmentalism, which is a social movement that seeks to protect the environment through lobbying, activism, and education. An environmentalist is a person who participates in environmentalism. In contrast, an environmental scientist, like any scientist, follows the process of observation, hypothesis testing, and field and laboratory research. What is Environment? The word environment is derived from French word ―environ‖ which means surrounding or enveloping. Environment can be defined as ―the specific physical, biological, social and cultural conditions in a given space (spatial) and time (temporal) which affect the survival, growth and development of human or other organisms‖. In simple words ―Environment is sum total of water, air and land interrelationships among themselves and also with the human being, other living organisms and property‖. The environment we live in determines how healthy we are, how fast we grow, how easy it is to move around, and even how much food we can obtain. Types of Environment The environment can be categorized on two broad bases; Classification of environment on the basis of nature Keeping in view the nature of environment, it can be broadly classified as; Page 1 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) 1. Biophysical environment 2. Social/Cultural environment Biophysical environment is further divided into biotic environment and abiotic environment. Biotic environment includes all living organisms and biological life such as animals, birds, forests, reptiles, insects, bacteria and micro- organisms like algae, fungus etc. Abiotic environment includes all non-living components such as land, mountains, rivers, air, water, temperature, humidity, water vapour, sand, dust, clouds etc. Social or cultural environment includes an individual’s social, economic and political condition wherein he lives. The moral, cultural and emotional forces influence the life and nature of individual behaviour. Classification of environment on the basis of scale Depending on the scale or magnitude, environment is divided into micro environment and macro or global environment. The immediate surroundings of a cell or an organism are termed as micro environment. On the other hand, environment of a large area (district, country and continent) is called macro or global environment. Importance of environmental science Today, the world is facing numerous environmental problems, ranging from local problems such as ground water depletion to global problems such as climate change. It is environmental science that familiarizes us about the causes, consequences, and remedial measures of different environmental problems. Importance of this subject can be realized from the below mentioned points.  It guides us to know how our developmental and day-to-day activities affect environment and how we are affected by changes in the environmental conditions.  It guides us to create a pollution-free environment (that is, clean air, water, land, and food) by adopting different methods of preventing and controlling pollution.  It guides us to utilize our natural resources such as water, forest, minerals, and fossil fuels in an efficient manner, that is, with maximum utility and minimum wastage, by adopting conservation and recycling strategies.  It guides common public to live an eco-friendly lifestyle by adopting the above three features, that is, knowing environmental implications of one’s activities, preventing and controlling pollution, and utilizing the resources efficiently in day-to-day activities. Page 2 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301)  It guides industries to operate in an eco-friendly mode by adopting clean and efficient technologies and installing pollution control systems.  It guides us to solve complex global environmental problems such as climate change, ozone-layer depletion, desertification, and energy crisis by using different interdisciplinary tools and approaches.  It guides the entire development process to become sustainable by ensuring equal distribution of natural resources between present and future generations, as well as by caring for nature in every walk of life in a holistic manner. Scope of Environmental Science Principles and approaches of environmental sciences are applicable in several areas of development. These areas are studied as scope of the subject. Environmental science has a vast scope since it covers a wide range of subject matters or issues related to our complex life-supporting system. Scope of the subject can be described in terms of major areas of applicability as well as career opportunities related to the subject. Three major areas of applicability of the subject are (i) Management of natural resources (ii) Conservation of ecosystem and biodiversity (iii) Prevention and control of pollution In addition, environmental science plays a key role in solving complex environmental issues of varying scale, including climate change, ozone layer depletion, energy crisis, desertification, urbanization, population explosion, and so on. Carrier opportunities for Environmental Scientists Scope of the subject in terms of career opportunities is fairly vast. For the last two decades, environmental science has been considered to be associated with a number of career opportunities. Major sectors/organizations which can hire environmental graduates are as follows.  Industries  Consultant firms  Research and development (R&D) organization  Environmental protection agencies/departments  Green media  Environmental law firms  University and higher education institutes Page 3 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301)  School education department  Non-profit organizations like The World Wide Fund for Nature (WWF Some important roles/positions for environmental graduates The graduates of environmental sciences are hired against one of the following positions in different government and private organizations.  Environmental assessment officer  Environmental consultant/ lawyer  Environmental policy analyst  Teacher and Researcher  Protected areas planner or manager  Land use planner  Wildlife manager  Natural resource manager  Conservation officer  Pollution prevention officer  Waste Management/Recycling Officer  Eco-tourism specialist  Renewable energy consultant Page 4 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-4 Components of Environment Introduction Scientific studies reveal that the earth’s life-supporting environment consists of four main spherical components that interact with one another—the atmosphere (air), the hydrosphere (water), the lithosphere (rock, soil, sediment), and the biosphere (living things). It is believed that human activities (urbanization, industrialization etc.) have tremendous impact on the environment by creating another component of the environment called anthrosphere. Atmosphere The atmosphere is a thin spherical envelope of gases surrounding the earth’s surface. The study of the atmosphere and its phenomena is called meteorology. Role of atmosphere Our current atmosphere provides us with protection against harmful solar and cosmic radiation, moderates surface temperatures, and is a major component of the hydrologic cycle. The atmosphere also plays an important role in nutrient and contaminant transport processes. Atmospheric Layers and Their Properties The atmosphere can be conveniently divided into five major layers namely troposphere, stratosphere, mesosphere, thermosphere and exosphere (Figure 1) which are separated by transitional zones (i.e., tropopause, stratopause, mesopause and thermopause), each of which has distinct properties. These layers have varying characteristics like pressure and density, temperature and heat, wind circulation and patterns, chemical composition and reactions, moisture and precipitation, and atmospheric pollution etc. Troposphere: The atmospheric layer closest to the Earth’s surface is the troposphere (Figure 1). Weather conditions (i.e., temperature, precipitation, wind, etc.) that influence our daily lives are confined to this layer, which varies in height from about 18 km above sea level at the equator to about 8 km above sea level at higher latitudes closer to the Earth’s poles. It contains the majority of the planet’s air that we breathe, consisting mostly of nitrogen (78% of the total volume) and oxygen (21%). The troposphere also contains most of the atmospheric mass and 99% of atmospheric water vapor. Stratosphere: Above the troposphere and tropopause lies the stratosphere, located approximately 20 to 45 km above sea level (Figure 1). Stratosphere contains the ozone (O3) layer that protects the Earth’s surface from harmful ultraviolet (UV) radiation. Temperature Page 5 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) increases in the stratosphere with increasing altitude due to the absorption of solar UV radiation by ozone (O3). Figure 1: Layers of atmosphere Mesosphere: Above the stratosphere and stratopause is the mesosphere, which extends from approximately 50 to 80 km above sea level (Figure 1). Within this layer, concentrations of both O3 and H2O vapours are minuscule, there is very little air, and atmospheric pressure is low. Temperature again decreases with altitude (0 to –95°C) because of a lack of molecules that significantly absorb solar radiation; about 99.9% of the atmospheric mass is below the mesosphere. Although the percentage of N2 and O2 in this layer is similar to that of air at sea level, the low density of this air would not provide sufficient O2 for humans and suffocation would occur in minutes. Thermosphere: The thermosphere is the ―hot layer‖ above the mesosphere, both of which are separated by the transitional mesopause zone (Figure 1). This layer extends from about 90 to 550 km above sea level. Temperature in this layer (–95 to 1200°C) cannot be determined directly due to the low density of the air. In fact, an air molecule in the lower thermosphere may travel a distance of 1 km before colliding with another molecule; in the upper thermosphere molecules may travel 10 km before a collision occurs. Page 6 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Exosphere: The outermost layer beyond the atmosphere is the exosphere, which extends to approximately 960 to 1000 km above sea level (Figure 1). This layer acts as a transitional zone between the primary layers of the Earth’s atmosphere and interplanetary space and is comprised primarily of hydrogen (H) and helium (He) at extremely low concentrations. This is the region where atoms and molecules are released into outer space. Page 7 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-5 Hydrosphere The hydrosphere refers to earth’s water in any form. The hydrosphere includes water bodies such as rivers, streams, lakes, and oceans as well as soil water, groundwater, glaciers, and polar ice caps. The water on the earth is found as liquid water (on the surface and underground), ice (polar ice, icebergs, and ice in frozen soil layers called permafrost), and water vapor in the atmosphere. The study of the chemical, physical, and biological properties and reactions of water bodies is called hydrology. The other fields related to hydrosphere are limnology (the study of freshwater systems), oceanography (the study of oceans) and geohydrology (the study of water in geological systems such as aquifers and groundwater environments). The transfer or movement of water from one component of the environment to another is called hydrological cycle. Importance of water Water is essential to all forms of life on Earth. It is also the central component to several life- sustaining biochemical processes. Water, as the ―universal solvent,‖ is essential for the transport of nutrients, gases, and organic compounds in the environment. Water is essential for plant growth by maintaining the turgor pressure. Similarly, freezing and thawing of water play an important role in soil formation. Further importance of water can be realized from the following facts.  Plants make their food with the help of water  Water is essential for our bodies to function properly  We need water for cleanliness  We need water while cooking our food  Water is used to produce electricity Distribution of water on the earth Although approximately 70% of the Earth’s surface is covered with water, an enormous amount of water is found belowground. By far the largest source of water is in oceans and seas, followed by ice (polar ice caps and glaciers) and then groundwater (Figure 2). Freshwater and saline lakes and inland seas represent the largest pools of liquid water on land, with rivers and streams comprising only a small fraction of the world’s water. The amount of water retained in soils is approximately 50 times greater than that in rivers and streams. While the atmosphere contains only a small fraction of the total amount of water Page 8 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) held in other pools, the quantity of water that passes through the atmosphere is immense and extremely important. Figure-2: Categorization of hydrosphere pools Page 9 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-6 Lithosphere Lithosphere by definition is the outermost layer which surrounds the earth (Figure 3). The earth is made up of three different layers (crust, mantle and core) of which only two (crust and part of mantle) belong to the lithosphere. The name 'lithosphere' comes from the Greek words lithos, meaning 'rocky,' and sphaeros, meaning 'sphere.' Geologists use the term as the name for the layer of the Earth extending from the surface to a depth of around 80 to 120 miles, depending on location, in which rocks are relatively brittle and rigid. Figure 3: Different layers of earth Importance of lithosphere The lithosphere is one of the most important layers of earth, because it is the place where all geological processes take place. Following points can be helpful to understand the importance of lithosphere.  It provides the solid surface necessary for terrestrial organisms.  It is a reservoir of nutrients that are essential for life  It holds deposits of fresh water and energy resources (coal, oil gas etc.).  Geographic variations of the lithosphere also affect climatic patterns.  The upper loose portion of the lithosphere called soil is essential for plant growth and food and feed production. Page 10 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301)  It also provided us various types of minerals such as iron, silver, manganese, aluminum, magnesium, calcium, and copper. Types and composition of lithosphere There are two types of lithosphere: oceanic lithosphere and continental lithosphere. Oceanic lithosphere is associated with oceanic crust, and is slightly denser than continental lithosphere. It is composed of elements such as oxygen, sulphur, aluminum, iron, calcium, and magnesium. The lithosphere is broken into several large segments called tectonic plates, which are moving relative to one another. Page 11 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-7 Biosphere The biosphere, (from Greek bios = life, sphaira, sphere) is the layer of the planet Earth where life exists. This layer ranges from heights of around 12 kilometres above sea level (used by some birds in flight) to depths of the ocean such as the Puerto Rico trench, at more than 8 kilometres deep. These are the extremes; however, in general the layer of the Earth containing life is thin: the upper atmosphere has little oxygen and very low temperatures, while ocean depths greater than 1.0 km are dark and cold. In fact, it has been said that the biosphere is like the peel in relation to the size of an apple. Simply put, the biosphere is the space on or near the Earth’s surface where land, air, and water interact with each other to support life. The biosphere is home to a splendid variety of plants, animals, birds, insects, reptiles and microorganisms (algae, fungi, bacteria, and virus etc.). Around 100 million species of living organisms are expected to exist on the earth. Significance of biosphere The biosphere plays an integral role to support the life of organisms and their mutual interactions. It is a vital element in climate regulation. Namely, a change in the biosphere triggers a change in climate. The significance of biosphere is summarized below.  Biosphere promotes life on Earth by harvesting energy from sunlight  It is helpful in nutrient cycling  It provides raw material for food, feed and shelter  It can be used as pollution marker  Different organisms of biosphere can be used to control environmental pollution  It also provide pharmaceutical compounds Components of biosphere The biosphere is comprised of three main components namely living (biotic) component, non-living (abiotic) component and energy. Living components The living components of the biosphere consist of three types of organisms called producers, consumers, and decomposers. The producers are generally plants; consumers are animals whereas decomposers are microorganisms. Plants- Plants are the primary producers and hence are very important. They produce their own food through the process of photosynthesis and are called autotrophs. Plants also help in Page 12 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) recycling of organic matter. Hence they also act as a source of energy for all living organisms. Animals- Animals are the primary consumers. As they do not produce their own food and depend on other sources for food, they are called heterotrophs. Animals use the organic matter from the plants as food. They transform the food into energy and utilize it for growth and development. Microorganisms- It includes virus, bacteria, algae, fungi etc. They are the major class of decomposers as they decompose the dead and decaying matter. By this process of decomposing they obtain their food. Non-living components The non-living component of the biosphere consist of the physical environment like soil, water, and air along with the inorganic substances like carbon dioxide, nitrogen, oxygen, water, phosphorus, sulphur, sodium, potassium, calcium, and other elements present in them. The factors like sunlight, temperature, pressure, and humidity are also a sort of non-living component of the biosphere and they constitute the climatic conditions. The climate in an area along with the nature of soil and water in that area determines the types of organisms which will be found in that part of the biosphere. Energy The major source of energy on earth is sun. Energy component is the vital part of the biosphere. Without this energy component, life is difficult on our planet Earth. It is with the help of this energy component that regeneration and reproduction is made possible. Page 13 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-8 Anthrosphere The anthrosphere/anthroposphere (sometimes also referred as technosphere) is that part of the environment that is made or modified by humans for use in human activities and human habitats. The anthroposphere can be viewed as a human-generated equivalent to the biosphere. While the biosphere is the total biomass of the Earth and its interaction with its systems, the anthroposphere is the total mass of human-generated systems and materials, including the human population, and its interaction with the Earth's systems. However, while the biosphere is able to efficiently produce and recycle materials through processes like photosynthesis and decomposition, the anthroposphere is highly inefficient at sustaining itself. Significance of anthrosphere The anthrosphere plays an increasingly prominent role in influencing changes within each of the other spheres. That is to say those human activities are impacting ice sheets, sea level, sea acidity, land cover change, biodiversity and atmospheric carbon dioxide concentrations. While by no means an exhaustive list, this should be enough to illustrate that the anthrosphere has a powerful and far reaching impact on planet Earth. Components of anthrosphere Components of the anthroposphere include: mines; agriculture; oil and gas fields; computer- based systems including the Internet; educational systems; landfills; factories; atmospheric pollution; urban development; transportation systems including roads, highways, and subways; nuclear installations etc. Page 14 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-9-11 Environmental problems and their sources Any human-induced change in the environment of an organism that causes an irreversible, adverse effect on its survival must be recognized as an environmental problem. Although the environmental problems are indeed diverse, but for the sake of simplicity we have summarized the various environmental problems as follows. Population growth The advances in modern science and technology that include breakthroughs in medical science have significantly decreased infant mortality and increased the human life span. The direct result is a burgeoning human population accompanied by a staggering demand for resources. Forecasts show that by 2050 this number will have grown to 8 billion if fertility rates stabilize. If they do not, human population may reach 12.5 billion. Although the general concern among demographers and some environmental scientists has largely centred on human population alone, what is equally important is the population size of domestic animals, such as cattle, sheep, goats, and horses. Collectively, their populations are estimated to number 3 billion, which we believe is an underestimation. Intensive agriculture Advances in agricultural sciences have included mechanized farming in the developed countries, cultivation of high-yield and disease-resistant varieties of crops, enhanced growth of crops from the application of fertilizers and irrigation, and decreasing crop losses to pests by using biocides (pesticides, herbicides, and such). This has greatly enhanced agricultural production for 50 or more years in both developed and developing countries. But now many problems with agricultural systems are increasingly realized. These include the heavy reliance on fossil fuels, a decrease in the quantity and quality of water for irrigation, the persistence of pesticides, fertilizer runoff, an increasing loss of agricultural productivity of soils, and the shrinkage of arable land. Deforestation Besides food, the prime resources of timber, pulp and paper, and biomass fuel come from the forests. Among environmental problems, deforestation was recognized early in the eighteenth century in Europe and in the nineteenth century in the United States. Forests have also been cleared for agriculture and for range lands. Even today, reports suggest that 13 million ha are Page 15 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) cleared each year 25 ha per minute. As important as these issues are, the vital roles of forests in the global water cycle and in climate change are also receiving widespread recognition. Mining for coal and minerals With increasing technological knowledge has come an increase in the myriad ways in which metals and minerals can be used. Thus, mineral use has increased several-fold. The extraction and processing of minerals require fuel energy. Thus, the mining of coal as a fuel energy source for mineral extraction and processing and for electric power generation has increased immensely. It has been estimated that from the dawn of human history to 1970, the cumulative production of coal was 140 billion tons; the cumulative production was approximately the same over the period 1970 to 2005, a mere 35 years. The role of coal in the economic growth of many nations is undisputed, but multiple environmental problems are involved in mining ores and coal, their processing, and generation of wastes. Transportation and urbanization To meet the needs of a rapidly growing human population, extensive transportation systems such as roads, railroads, and air travel have become inevitable. The advent of automobiles and their convenience have resulted in an unprecedented increase in their numbers. This has facilitated longer distance commutes between the workplace and home, making living farther and farther from cities possible. The result: unprecedented suburban growth and development, resulting in the phenomenon that we now refer to as urban sprawl. Quantity and quality of water Water is one of the basic necessities of life, yet more than half of the world’s 6 billion persons suffer from a shortage of water. There are multiple reasons for this shortage; the primary one, of course, is that freshwater constitutes less than 3% of the world’s water, while the remaining (salty) 97% is found in the oceans. The scarcity of freshwater has been exacerbated because we already use 70% of the supply, with water use rising six fold in the last 70 years. Additionally, contaminants that result from what we do on land or send to the atmosphere often end up in water bodies. This degrades water quality, producing unsafe drinking water that contains waterborne diseases and claims the lives of millions of children each year. Water allocation is a prominent factor in disputes between countries that lack an adequate water supply. Air quality and the loss of stratospheric ozone The quality of the air we breathe has a direct bearing on our health. Estimates are that more than a quarter of the world’s population, or 1.5 billion people, breathes air that is unhealthy. Page 16 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Air contaminants also find their way into other biota and ecosystems, with deleterious effects. Considerable progress has been made in the last 30 years to improve the quality of air in the United States, although rapidly developing countries such as China suffer from serious air pollution problems. However, the use of certain chemicals called chlorofluorocarbons or CFCs (trade name Freon), a twentieth-century phenomenon, has sent stable chlorine compounds up into the stratosphere, where, on a global basis, they degrade the ozone layer that otherwise keeps much of the sun’s ultraviolet rays from penetrating to the Earth’s surface. The greenhouse effect and climate change Human activities lead to the emission of a number of gases to the atmosphere that have a long residence time and a warming potential. These gases, referred to collectively as greenhouse gases or GHGs, include carbon dioxide, methane, nitrous oxide, water vapours, and CFCs. They trap heat closer to the Earth’s surface, thereby causing warming by what is known as the ―greenhouse effect.‖ Studies from a number of scientific disciplines now show conclusively that GHGs have considerably altered the temperature relations of the lower atmosphere. The changing temperature relations will have far-reaching impacts on nearly all regions of the world. Loss of habitat and biodiversity The first five activities briefly mentioned earlier have transformed natural land areas in significant ways. The extent of such disturbance is truly staggering, and we know its magnitude only in an approximate way. In a widely cited report issued nearly 21 years ago, the Food and Agricultural Organization of the United Nations estimated the Earth’s disturbed areas at 2,000 million ha, with five to 7 million ha added each year. An August 2003 report from the United Nations Convention to Combat Desertification notes ―the loss of 250 million acres [more than 100 million ha] a year of fertile soil due to deforestation, drought, over-grazing and climate change.‖ The result has been loss of habitats for organisms, rendering many species endangered or extinct. The loss of each such species means the potential loss of new sources for drugs, food, and fiber. Complicating this is the increasing invasion and survival success of many exotic species. Resource loss and pollutant gain Collectively, changes in the environment from land transformation, overharvesting, and overconsumption have resulted in the degradation and loss of productivity in many areas. Such changes are not restricted to land areas alone; human activities have had significant Page 17 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) impacts on aquatic resources as well. For example, fish catches globally have fallen, and populations of important species such as Atlantic cod, haddock, and herring have fallen considerably. At the same time, undesirable chemicals are present in nearly all environments, leading to global treaties on compounds known as persistent organic pollutants (POPs). Page 18 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-12-13 Environmental pollution and its types Environmental pollution Environmental pollution is the process of contamination of environment by the addition of pollutants/contaminants which makes the environment harmful/useless for its habitants/living organisms. One of the serious issues faced by our modern world is environmental pollution, and it is one the most significant challenges that the world is facing in our day. Without a doubt, Environmental pollution has existed for centuries. But, it began to be a severe issue following the industrial revolution in the 19thcentury. Pollutants or contaminants and their types Any substance or form of energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource is called pollutant or contaminant. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values. Pollutants may be classified by various criteria as mentioned below: (1) By the origin: whether they are natural or man-made (synthetic). (2) By the effect: on an organ, specie, or an entire ecosystem. (3) By the properties: mobility, persistence, toxicity. (4) By the controllability: ease or difficulty of removal. Sources/causes of pollutants Generally, pollutants are released into the environment by human (anthropogenic) activates and natural factors. But, pollutants released by human activities are of more serious concerns due to their nature and amount released. Some most important sources/causes of pollutants are;  Industrial activity  Urbanization  Transportation  Agriculture practices  Trading activity Types of environmental pollution Depending on the nature and source of pollutants and component of the environment they are polluting or affecting, pollution can be categorized into following 7 types. Page 19 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) 1. Soil Pollution The addition of chemical and biological substances in the soil which negatively influence the soil quality and minimize its use as a resource is called soil pollution. Soil pollution takes place when chemical pollutants contaminate the soil or degraded by acts such as mining, clearance of vegetation cover, or topsoil erosion. Usually, it happens when human activities directly or indirectly introduce destructive chemicals, substances, or objects into the soil in a way that causes damage to the immediate earthly environment. 2. Water Pollution Water pollution is the act of contaminating water bodies including rivers, oceans, lakes, streams, aquifers, and groundwater. It occurs when foreign harmful materials like chemicals, waste matter, or contaminated substances are directly or indirectly discharged into water bodies. Any alterations in the chemical, physical, or biological water properties qualify as water pollution. Very often, the primary contributors to water pollution are human activities since they introduce substances that contaminate the water with harmful chemicals and toxic materials. Water pollution is categorized into point source, non-point source, and groundwater. Point source water pollution occurs when the contaminants enter a water body from a single identifiable source while non-point source occurs as a result of cumulative effects of different amounts of contaminants. 3. Air Pollution Air pollution is the introduction of harmful substances in the air that results in detrimental impacts to the environmental and humanity. Air pollution simply makes the air unclean or contaminated. It occurs when harmful substances such as foreign gases, odours, dust, or fumes are released in the air at levels that can harm the comfort or health of animals and humans, or even destroy plant life. Examples of air pollutants (substances that pollute the air) include hydrocarbons, organic compounds, dust particles, carbon monoxide, sulphur oxides, and nitrogen oxides. 4. Noise pollution Noise pollution is mostly an undesirable sound or sound which generates horrible discomfort on the ears. Noise pollution is defined as unpleasant and undesirable sound levels that cause serious discomfort to all living things. It is measured in decibels (dB). Sound levels beyond 100 dB can cause permanent hearing loss, and noise of around 90 dB causes auditory weakness. The industrial sound limit according to the World Health Organization (WHO) is 75 dB. In the contemporary society, noise has become a permanent aspect owing to the daily Page 20 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) activities such as transportation, industrial manufacturing, and technology. In contrast to the other types of pollution, noise pollution lacks the element of accumulation in the environment. It merely occurs when sounds waves of intense pressure reach the human ears and may even affect the body muscles due to sound vibrations. Noise pollution similarly affects marine and wildlife animals in the same manner it affects humans, and can even cause their death. 5. Thermal pollution Thermal pollution occurs when water bodies are degraded in terms of altering their temperatures. Commonly, it happens when people or industries undertake activities that suddenly decrease or increase the temperature of a natural water body which may include lakes, rivers, oceans or ponds. In the current era, thermal pollution is a huge menace and is mainly influenced by power plants and industrial manufacturers that use water as a coolant. Urban storm water runoff from parking lots and roads also discharges water of elevated temperatures into adjacent water bodies. 6. Radiation pollution Radiation/radioactive/radiological pollution or nuclear pollution refers to the entry of radioactive materials which release the harmful radiations into the environment. Radiations are categorized as ionizing radiations and nonionizing radiations. Ionizing radiations include alpha (α) particles; beta (β) particles and gamma (𝛾) radiations while nonionizing radiations comprise radiowaves, microwaves, visible radiation and ultraviolet radiations etc. Ionizing radiations are more harmful due their high energy and ionizing power. These radiations cause diseases and mutation in living organisms. Radioactive substances are releases into the environment during nuclear explosions and testing of nuclear weapons, nuclear weapon production and decommissioning, mining of radioactive ores, handling and disposal of radioactive waste, and accidents at nuclear power plants. 7. Light pollution Light pollution occurs due to lengthened and excessive use of artificial lights, such that it results in the brightening of the skies at night. As a consequence, it upsets the activities and natural cycles of wildlife and also affects the welfare of humans. Whenever artificial lights are used where they are not intended, it causes a nuisance. For instance, too much outdoor light intruding into neighbour’s bedrooms can disrupt their sleep. Likewise, too much indoor light has implications on the health of the inhabitants of that room. Light pollution is also referred to as luminous pollution or photo pollution. Page 21 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) Lecture-14 Impact of pollution on ecosystem Ecosystem An ecosystem is defined as a structural and functional unit of biosphere consisting of community of living beings and physical environment, both interacting and exchanging materials between them. It includes all of the living things (plants, animals and other organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sunlight, soil, climate, atmosphere etc.). The study of Ecosystems mainly consists of the study of certain processes that link the living, or biotic, components to the non-living, or abiotic, components. Energy transformations and biogeochemical cycling are the main processes that comprise the field of ecosystem ecology. As we learned earlier, ecology generally is defined as the interactions of organisms with one another and with the environment in which they occur. We can study ecology at the level of the individual, the population, the community, and the Ecosystem. Components of ecosystem and their functions There are two main categories of components of ecosystem which are termed as biotic (living) components and abiotic (non-living) components. Living components: Every ecosystem is made up of three broad living components: producers, consumers and decomposers. Producers, also called autotrophs, are organisms that create food from inorganic matter. The best examples of producers are plants, lichens and algae, which convert water, sunlight and carbon dioxide into carbohydrates. Consumers are organisms that cannot create their food. Instead, they consume the food generated by producers or consume other organisms that have in turn consumed producers. Many insects and animals are consumers. Decomposers break down dead or dying organic matter. Examples of decomposers include detritus feeders such as earthworms and sowbugs, as well as some fungi and bacteria. Scavenger animals can also be thought of as decomposers. The producers are the foundation of any ecosystem. They create the matter, or biomass, that sustains the rest of the ecosystem. Non-living components: The non-living (abiotic) components of an ecosystem create and define the ecosystem's environment and include sunlight, temperature, precipitation, weather, landscape, soil chemistry, water chemistry and even base nutrient supply. These abiotic components remain vital to the ecosystem’s health because they are keystones in its energy Page 22 of 23  DEPARTMENT OF SOIL AND ENVIRONMENTAL SCIENCES Introduction to Environmental Science (SES-301) flow and nutrient cycle. Energy from sunlight is transformed into chemical energy through photosynthesis by plants, which define the base producers in most ecosystems. Essential nutrients and elements such as carbon, nitrogen, oxygen etc. are necessary for the biochemical processes of life are obtained from the surrounding atmosphere, soil, water and the physical environment. Energy and elements are endlessly cycled within the ecosystem because of the interaction between its biotic or living and abiotic, non-living elements. Impact of pollution on components of ecosystem As discussed earlier, ecosystem comprises of various biotic and abiotic components. These components of the ecosystem are interacting with one another to maintain the balance in ecosystem. This balance is essential for normal functioning and ecosystem services. Environmental pollution has been reported to disturb the balance of ecosystem by negatively influencing the different components of ecosystem. Some most prominent impacts of pollution on ecosystem are summarized below.  Environmental pollution decreases the plant growth and productivity by interfering with biochemical and physiological processes.  It also threatens the survival, growth and development of animals and wildlife due to feed starvation and habitat change.  Pollution of water bodies by the addition of toxic substances is also a major cause of increased mortality of aquatic animals and plants  Different types of pollution also cause many diseases and disorders in human  Addition of pollutants in the soil deteriorates the physical, chemical and biological properties of soil reducing its utilization. Page 23 of 23