MEV 011: Unit 01 - Introduction to Environmental Science

Unit 1 - Introduction to Environmental Science

 1.0 Introduction

The environmental science emphasise on the need for equitable, ethical, and sustainable use of Earth’s resources by a global population that nears the carrying capacity of the planet. Emissions generated by human activity continue to alter the composition of the atmosphere, leading to air pollution, climate change, stratospheric ozone depletion and exposure to persistent, bioaccumulative and toxic chemicals.

Genetic diversity is declining, threatening food security and the resilience of ecosystems, including agricultural systems and food security.

Biodiversity loss and degradation of natural environment, unsustainable agricultural practices; the spread of invasive species; pollution, including microplastics; and overexploitation, including illegal logging and trade in wildlife are few of the environmental concerns.

Environmnetal Science enables us not only to understand how human behaviors affect the environment, but also the scientific principles that govern interactions between the living and non-living.

1.1 Objectives

After studying this unit, you should be able to:

•        define environmental science and distinguish it from related fields such as environmental studies, ecology, and geography;

•        explain the universe’s complexity through a hierarchical framework that includes consideration of Earth, life, and ecosystems at various scales;

•        identify key principles of the ecosystem approach to conserving natural resources;

•        explain segments of the environment;

•        define scope of environment; and

•        explain the need for public awareness in detail.

1.2 Definition and Principles of Environment

Definition of Environment

The word ‘environment’ is most commonly used to describe nature and means the sum of all living and non-living things surrounding an organism or group of organisms. The environment includes all elements, factors, and conditions that impact the growth and development of certain organisms. The environmentincludes biotic (all surrounding living organisms) and abiotic factors (light, temperature, water, atmospheric gases) that influence observed organisms.

The term ‘Environment’ is used for surroundings and is derived from French word ‘environ’ or ‘environner,’ which means around or encircle or surroundings. The environment may be defined as the complex of climatic, biotic, social, and edaphic factors that act upon an organism and determines its form and survival. The environment provides resources that support life on the earth and help in the growth of a relationship between living organisms and nature.

The environmental science can be defined as “an interdisciplinary study of how the Earth works, how we are affecting the Earth’s life-support systems (Environment), and how to deal with the environmental problem we face”. The environmental science is the study of the human impact on the physical and biological environment of an organism.

Element of Environment

The environment is constituted broadly of two components, i.e., non-living or physical and living or biological. Non-living or physical includes air (atmosphere), water (hydrosphere), and soil (lithosphere). Living or biological consists of plants, microbes, animals, humans, etc., and collectively are known as the biosphere.

Principles of Environment

This section highlights the basic environmental principles and emphasizes our ecosystem because this is the only way we, our planet, can be protected, and actions should be taken to solve our environmental problems.

1)      Nature knows best: Humans must understand nature and follow its rules to ensure a continuous and steady supply of resources; one must not go against natural processes. If any disruption is caused in the cycle of nature, this can bring imbalance to our ecosystem.

2)      All forms of life are important:  Each organism plays a fundamental role in nature. It is easy to appreciate beautiful organisms like butterflies, especially if one knows their important role in pollination. The giant ones like elephants, whales, and alligators are the ones we respect mixed with fear or wonder and their products. But when it comes to unlovely, squirmy, and troublesome creatures, this principle is unusually overlooked.

3)      Everything is connected to everything else: In an ecosystem, all biotic and abiotic components interact to ensure that the system is sustained. Any intrusion from outside may cause an imbalance and collapse of the system.

4)      Everything changes: The environment is continuously changing. Organisms also develop through time. However, these natural changes have affected these changes with our current technology now cause problematic events for us. Humans should rethink their relationship with the environment. Because our belief that it is beneficial to the environment often turns out to be catastrophic.

5)      Everything must go somewhere: Everything ends up elsewhere. It doesn’t just disappear. For example, if you throw a piece of candy wrapper away, it disappears but does not cease to exist. It ends up elsewhere. Gases released in the atmosphere may spread, but they will end up a component of the atmosphere and be brought down by rains. Any particular type of waste should always be a concern to us. It may be a pollutant or a resource, depending on certain factors. Be a responsible person and throw your trash in a proper place.

6)      Ours is a finite earth: Earth’s resources can be classified as either renewable or non-renewable. Renewable resources are those that can be quickly replenished by natural cycles (e.g., water, air, plants, animals), while non-renewable resources are those that cannot be replenished through natural cycles. Although renewable resources can be replenished, it is important to understand that these are renewable only if they are not overused and not destroyed by factors such as pollution.

7)      Nature is beautiful, and we are stewards of God’s creation! : Among all creatures, humans are the only ones made in God’s image and have been given the right to have dominion over all his creations. Being the most intelligent and gifted with reason, humans can manipulate and create changes in nature for their own advantage. Yet, creation exists not to be ravaged or abused but to be taken care of. Humans cannot exist without nature. They are conatural with the environment they live in.

1.3 Structure and Components of Environment

The environment generally represents four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere; these correspond to rocks, water, air, and life. Therefore, the environment can be defined as the study of the earth, air, water, living beings, and mutual relationships.

1.3.1 Atmosphere

The atmosphere (or air) is a layer of gases surrounding the Earth and retained by its gravity. It reaches over 560 km from the surface of the earth. The atmosphere absorbs the sun’s energy, recycles water and other chemicals, and works with the electrical and magnetic forces to provide weather and climate phenomena. The atmosphere also protects us from high-energy radiation and the frigid vacuum of space. Atmospheric gases scatter blue light more than other wavelengths, giving the earth a blue halo when seen from space. Dry air contains about (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and a trace amount of other gases.

There is not any definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. The Kármán line, at 100 km, is considered the boundary between the atmosphere and outer space. The three-fourth mass of the atmosphere belongs within 11 km of the surface.

Composition of atmosphere

The atmosphere is comprised of mainly gases and water vapours. Fairly large amounts of nitrogen, oxygen, and argon are present as elementary gases in the lower atmosphere. These gases are found in varying amounts at different heights in the atmosphere. It is mainly dense up to 1 km elevation. The density of air at sea level is about 1.2 kg/m³. The atmospheric density decreases as the altitude increases.

The general composition of the atmosphere is given in the following table.

Gases	Volume (percent)
Nitrogen (N2)	78.08
Oxygen (O2)	20.95
Argon (Ar)	0.93
Carbon dioxide (CO2)	0.035
Neon (Ne)	0.002
Helium (He)	0.0005
Methane (CH4)	0.0002
Krypton (Kr)	0.0001
Hydrogen (H2)	0.00005
Nitrous oxide (N2O)	0. 0.0003
Carbon monoxide (CO)	0.00002
Xenon (Xe)	0.000009
Ozone (O3), Nitrogen dioxide (NO2), Iodine (I), Ammonia (NH3)	Traces

Structure of atmosphere

The pressure and temperature are related to altitude within the atmosphere. Due to the compressible nature of gases, the earth’s gravity causes atmospheric pressure to increase as elevation decreases. However, the air temperature decreases at some levels and increases at others with an increase in altitude. These temperature variations result from the variation of chemical and physical properties of the different atmospheric layers as described below.

Troposphere

The troposphere is originated from the Greek word “tropos,” which means ‘to turn’ or ‘to change.’ It is the lowest and most dense layer of the atmosphere, begins at the ground or sea, and reached up to 10-12 km, with some variation due to weather factors and thermal convection. The troposphere is characterized by a continuous decrease of atmospheric temperature with increasing altitude, and most of the weather phenomena like cloud formation and thunderstorms occur in this region.

The troposphere contains roughly 80% of the atmosphere’s total mass and contains almost all water vapour of the atmosphere. The important chemical species are CO2, H2O, and NO2. The uppermost boundary of the troposphere is called the tropopause. The height of the tropopause depends on geographical latitude and weather conditions.

Stratosphere

The word stratosphere originates from the Latin word “stratum”, meaning layer. The stratosphere lies above the troposphere to about 50 km. The atmospheric temperature increases along with increasing altitude and reaches 0°C at about 50 km show a negative lapse rate. This increase is mainly caused by the ozone that absorbs the UV radiation coming from the sun. This region’s main functions are absorption of UV rays through the ozone layer and protect the earth from harmful radiations. About 90% of the ozone in our atmosphere is present in the stratosphere. Ozone concentrations are greatest between about 20 and 40 km, ranging from about 2 to 8 ppm. The atmospheric pressure in this layer is about 1/ 1000th of sea level.

The stratosphere is almost without clouds because water vapours from the troposphere are very limited due to the extremely low tropopause temperature. The stratosphere may be divided into a lower stratosphere with a constant temperature of about -56°C and an upper stratosphere above 20 km of height, where temperature increases to about 0°C by absorption of UV radiation. The uppermost portion of the stratosphere is called stratopause and characterized with a temperature of approximately 0°C and distinguished as the warmest region between the mesosphere and the stratosphere.

Mesosphere

Derived from the Greek word “meso,” means middle, the mesosphere extends from about 50 km to the range of 80–85 km. Temperature decreases with height reaching -100 °C in the upper mesosphere. Most meteors burn up when entering the atmosphere. It is the coldest place on earth’s atmosphere, with a minimum temperature of -100 °C at the mesosphere’s uppermost boundary. The boundary between the mesosphere and the thermosphere is called mesopause.

Thermosphere

The thermosphere named from the Greek word ‘Thermos’ means heat and begins from 85 to 500 km. The temperature can rise to 1500 °C in this region. The International space station orbits are situated in this layer in between 320 and 380 km. The boundary above the thermosphere varies in height from 500- 1,000 km. The thermosphere exhibited a negative lapse rate and is characterized by the high kinetic energy of gas molecules.

Exosphere

The exosphere is the outermost layer of the atmosphere and extends from the outer thermosphere known as exobase, at the height of about 500 km, to the edge of interplanetary space (about 10,000 km). It contains free-moving particles that may migrate into outer space. The region where atoms and molecules have sufficient velocity to escape from the earth’s gravitation into space is referred to as the exosphere.

Ionosphere

The atmosphere ionized by solar radiation extends from near about 50 to 1000 km and typically overlaps the mesosphere, the thermosphere, and the exosphere. Ionosphere may be divided into D (50 - 90 km), E (about 90-150 km), and Flayers (150 - 800 km). The ionosphere is an example of plasma, neither gas, liquid, nor solid; it is the fourth state of the matter and represents 99% of visible matter in the Universe. The dominant ions in the D and E layers are NO⁺ and O₂⁺; in the F region, where the bulk of the ionospheric plasma resides, O⁺ predominates. These layers play an important role in communication engineering since they reflect radio waves (short waves).

1.3.2 Hydrosphere

The word “hydrosphere” is generated from two Greek words ‘hydro’ means water, and ‘sphaira’ means sphere and, in a nutshell, can be defined as the combined mass of water found on, under, and over the surface of the planet. The hydrosphere is composed of all the waters on or near the earth, including oceans, rivers, lakes, and moisture in the air.

Hydrosphere covers about 70% of the earth’s surface and provides a home for many plants and animals. The hydrosphere contains about 1.36×109 km3 liquid in the form of water. The second most common form of the water molecule on our planet is ice that is sufficient to raise the sea level by about 70 meters. Ninety-seven percent of the earth’s water is present in the ocean. The remaining three percent is freshwater. Three-quarters of the freshwater present in solid form and exists in ice sheets.

Water is highly essential for life and a major constituent of almost all life forms. Most life forms like plants and animals contain more than 60% water by volume of their body. Without water, life on the planet would probably never have developed. The abundance of water on earth is a unique feature that clearly distinguishes our “Blue Planet” from other solar system planets. The ranges of surface temperatures and pressures of our planet permit water to exist in three states viz. solid (as ice), liquid (as water), and gas (as water vapours).

1.3.3 Lithosphere

The lithosphere, also known as the Geosphere, is the “solid” part of the Earth and consisted of crust and upper mantle. The crust is the Earth’s outermost layer, varies from 5 to 70 km in thickness, made up of rocks, minerals, and soil. The crust is inorganic and is composed of minerals. There are two kinds of crust, i.e., continental and oceanic. The crust is constantly moving, and by the movement of continents, earthquakes happen.

Earth’s oceanic crust is a thin layer of dense rock about 5 km thick. The continental crust is less dense than oceanic crust, and lighter-colored rock that varies from 30 to 70 km are also present in it. These crusts are made mainly of eight elements: Oxygen, Silicon, Aluminium, Iron, Calcium, Sodium, Potassium, and Magnesium. The oceanic crust has more Silicon, Oxygen, and Magnesium, while the continental crust is rich in Aluminium.

1.3.4 Biosphere

The term “biosphere” was coined by the famous geologist ‘Eduard Suess’ in 1875 and was defined as the place on earth’s surface where life dwells. The biosphere begins through the process of biogenesis about 3.5 billion years ago. The biosphere is composed of all living organisms (from the smallest bacterium to the largest whale). Most of the life is found from 3 m below ground to 30 m above the ground and in the top 200 m in the oceans and seas.

The biosphere is divided into biomes, inhabited by broadly similar flora and fauna. The biomes are classified based on the climate and geography of the region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Each biome consists of more than one ecosystem whose communities have adapted to smaller differences in climate and the environment of the biome.

1.4 Multidisciplinary Nature of Environmental Studies

Environmental science is a multidisciplinary or interdisciplinary subject which deals with every aspect of life. That requires the knowledge of various subjects like biology, chemistry, physics, microbiology, biochemistry, statistics, geology, economics, management, law, sociology, etc. Environmental study has evolved from the integrated use of many disciplines. Thus the environmental study requires the knowledge developed in many different disciplines, e.g. Life sciences, including botany, zoology, genetics, ecology, biochemistry, biotechnology, microbiology, etc., help understand the environment’s biotic components

Physical sciences, including chemistry and physics, geology, atmospheric science, oceanography, geography, etc., provide knowledge of the physicochemical structure of the environment’s abiotic components.

Economics, sociology, management, mass communication furnish inputs to deal with socio-economic aspects associated with various developmental activities.

Mathematics, statistics, computer science, serve as effective tools in resources management.

Synthesis of civil engineering, hydraulics, chemical engineering, and nanotechnology provides the technical solutions to environmental pollution control and waste treatment that are extremely important for protecting the environment.

·         Political science and environmental law provide a tool for the guidelines and judicious management for effective management and environment protection.

·         Education and mass communication helps in making people aware of various environmental problems and their solutions.

The study of the environment with a multi-disciplinary approach helps to generate a sustainable use of resources for present and future generations.

1.5 Scope of the Environment

The environment includes all those areas which can affect well being of living organisms and must be related to all processes which would affect the wellbeing, whether it is physical (global warming, climate change, etc.), chemical (ozone layer depletion), or biological (deforestation). Atmosphere, hydrosphere, lithosphere, and biosphere are the four segments, which make environment.

Atmosphere saves us from the hostile environment of outer space. It also protects us from cosmic, UV, and electromagnetic radiations. Hydrosphere provides water to all organisms, and the lithosphere provides minerals, nutrients, etc., which take part in biomass’s primary production. The biosphere designates living organisms’ realm by creating their interactions with air, water, and soil; without that, life will not exist anymore.

Environmental sciences provides knowledge about what we should do to make a sustainable environment and what should not. It suggests solutions to combat the forthcoming problems/disasters, viz. global warming, environmental pollution, climate change, etc. It also tells about the components of the environment, the issues affecting the environment, the role of organisms in these issues, how best we can handle the negative issues, and how best to enhance the positive ones.

1.6 Need for Public Awareness

The unthoughtful and unabated consumption of natural resources to fulfill different needs such as the development of sciences, technologies, agriculture, industries, transport and communication services, comfort, and pleasure has depleted the natural resources and degraded the vital life-supporting systems, e.g., air, water, and soil besides disturbing the delicate ecological balance.

Hence, to improve the deteriorated environment and avoid further pollution, degradation of natural resources, and maintaining sustainable ecological balance, there is a strong need to educate everybody to contribute to protecting our environment by using natural resources in an eco-friendly manner and avoiding further pollution.

Environmental issues received international attention about 36 years back in Stockholm Conference, held on 5 June 1972. Since then, we celebrate World Environment Day on 5 June. The United Nations Conference on environment and development held in Rio de Janeiro in 1992, popularly known as ‘Earth Summit,’ first highlighted the key issues of global environmental concern and attracted the general public’s attention toward the degrading environment.

Any Government on its own can not achieve the goals of sustainable development until the public has not participated actively. Public participation is possible only by generating awareness about ecological and environmental issues. Individuals can actively participate in the progression of environmental improvement in the following ways.

1)      By minimization of natural resources consumption and saving them from unwanted exhaustion such as rainwater harvesting, etc.

2)      Energy should not be harnessed too much from fossil fuels’ burning (solid fuels like coal, coke, etc. in thermal power plants, liquid and gaseous fuels like petrol, diesel, LPG, automobiles, etc.

3)      By step down in cutting trees for timber production to get aesthetic pleasure, such as drawing rooms and houses.

4)      Every individual can formulate and obey the moral codes meant for achieving a better environment.

5)      By preserving the greeneries and wildlife on a vast area of land.

The main goals targeted by various environmental scientists to protect our environment include:

Ø  Reduction of pollution from all sources to get zero pollution in future.

Ø  Reduction, Recycling, and Reuse of waste materials.

Ø  Cleanly converting non-recyclable materials into energy through direct combustion or after conversion into secondary fuels.

Ø  Minimizing societal consumption of non-renewable fuels.

Ø  Development of alternative, green, low-sulfur, and renewable bio-energy sources.

Ø  Conservation and sustainable use of various natural resources, viz. water, land, and air.

Ø  Protection of representative ecosystems.

Ø  Preservation of threatened and endangered species.

Ø  The establishment of National Park, Sanctuaries, and Biosphere Reserves to protect the biodiversity and ecosystems.

1.7 Importance of Environment

The environment is never static. The physical forces continuously change the earth’s surface through weather, waves, and natural phenomena, such as earthquakes, volcanoes, etc. These phenomena release gases, heat, vapour, and dust into the atmosphere and reach the land or sea at a great distance from their sources. Ozone is produced in the high atmosphere by chemical reactions and protects us from harmful ultraviolet radiation coming from the sun.

The environment belongs to all and is important to all without making any differentiation between races, ages, types, etc. The importance of the environment lies in the fact that human beings, well acquainted with nature, can lead a healthy, spiritual, and long life. Study of environment helps us to maintain sustainable environment all through in our vicinity.

A few importances of environmental science are pointed out below:

•        Environmental science is concerned with the day to day interaction with the surroundings, which are closely related to living beings

•        Associated with most of the branches of science in an interdisciplinary approach

•        Concerned with the importance of wildlife and its protection

•        Explains the significance of biodiversity conservation in establishing an ecological balance

•        Deals with different types of ecosystems, biotic and abiotic factors, and their role in maintaining the ecological balance

•        Concerned with different types of food chains, food webs, ecological pyramids, productivity, biomass production, carrying capacity of ecosystems, etc.

•        Deals with various inter-relationships that exist between living organisms and non-living things and among different living organisms such as symbiosis, mutualism, commensalisms, parasitism, competition, antibiosis, etc.

•        Describes the impact of population growth on the resource consumption, national economy, and sustainability

•        Deals with the impact of ethical principles in the conservation of wildlife, biodiversity, and ecosystems

•        Gives information about water conservation, watershed management, rainwater harvesting, and their importance in various physiological, biochemical, internal, and external environments.

•        At present, many environmental issues have grown in size and complexity day by day, threatening humanity’s survival on earth.

Environment science have become significant for the following reasons:

1)      The global environmental issues are global warming, ozone layer depletion, dwindling forest and energy resources, loss of global biodiversity, etc.

2)      The localized environmental problems include the impact of mining, a hydraulic project in an area, disposal, and management of solid waste, river and lake pollution, soil erosion, water logging, salinization of soil, heavy metal pollution, etc.

3)      A few environmental problems associated with an individual are safe and clean water, hygienic living conditions, clean and fresh air, fertile land, healthy food, etc.

The importance of the environment can also be understood by different environmental celebrations given in Table below.

Environmental celebration	Date
World wetland day	2 February
World forest day	21 March
World day of water	22 March
World meteorological day	23 March
National Maritime day	5 April
Earth day	22 April
International biodiversity day	22 May
Anti-tobacco day	31 May
Van Mahotsava week	1-7 June
World Environment day	5 June
World ocean day	8 June
World day to combat desertification and drought	17 June
World population day	11 July
Ozone Week	16-23 September
World car-free day	22 September
Green consumer day	28 September
World farm animal day	2 October
World habitat day	3 October
Wildlife week	1-7 October
World food day	16 October
World conservation day	24 October
International day for natural disaster reduction day	13 October
National Children day	14 November
World fishery day	21 November
National Land resource and conservation week	21-27 November
World Aids day	1 December
Global day of action against corporate crime (Bhopal Gas tragedy day)	3 December
International Mountain day	11 December
National Energy conservation day	14 December

1.8 Let Us Sum Up

We have studied in this unit about the definition and importance of the environment. We have discussed in detail the scope, importance, and need for public awareness to preserve the environment. We have also described various international efforts that have been made to protect the environment.