ENVIRONMENTAL GEOLOGY
Environmental Geology – fundamental concepts – its scope, objectives and aims – dimensions of 2-Sustainability
environmental stress-scope of environmental geosciences. Ecological perspective of environment – Concepts
of ecosystem – Earth’s major ecosystem, terrestrial and aquatic. Role of geologist in environmental studies. Sustainability is development which ensures that future generations will have equal access to the resources
Status of environmental consciousness in India – EPA. Man and Environment. Geological factors of that our planet offers. Sustainability also refers to types of development that are economically viable, do not
Environmental Health. Need for environmental protection, balancing economic development. Climate change, harm the environment, and are socially just. Sustainability is a long-term concept, something that happens
carbon sequestration and carbon budgeting. over decades or even hundreds of years.
Sustainability related to respect to use of resources is possible for renewable resources such as air and water.
Environmental geology is applied geology. Specifically, it is the use of geologic information to help us solve Sustainability development with respect to nonrenewable resources such as fossil fuels and minerals is
conflicts in land use, to minimize environmental degradation, and to maximize the beneficial results of using possible by:
our natural and modified environments. The application of geology to these problems includes the study of
the following (Fig.1): - Extending their availability through conservation and recycling
- Focusing on when a particular nonrenewable resource is depleted, focusing on how that mineral is
1- Earth materials, such as minerals, rocks, and soils to determine how they form, their potential use as used and developing substitutes for those uses.
resources or waste disposal sites, and their effects on human health
Environmental Crisis?
2- Natural hazards, such as floods, landslides, earthquakes, and volcanic activity, in order to minimize
loss of life and property. Demands made on diminishing resources by a growing human population and the everincreasing production
3- Land for site selection, land use planning, and environmental impact analysis. of human waste have produced what is popularly referred to as the environmental crisis. This crisis in world
4- Hydrologic processes of ground water and surface water resources and water pollution problems. is a result of overpopulation, urbanization, and industrialization, combined with too little ethical for our land
5- Geologic processes, such as deposition of sediment on the ocean floor, the formation of mountains, and inadequate institutions to cope with environmental stress.
and the movement of water on and below the surface of Earth, to evaluate local, regional, and global The rapid use of resources continuous to cause environmental problems on a global scale, including the
change. following:
Fundamental Concepts of Environmental Geology 1- Deforestation and accompanying soil erosion and water and air pollution occur on many continents.
2- Mining of resources, such as metals, coal, and petroleum, whatever they occur produces a variety of
There are main five concepts for studying the environmental geology: environmental problems
1- Human population growth, 2- Sustainability, 3- Earth as a system, 4- Hazardous earth process and 5- 3- Development of both groundwater and surface water resources results in loss of and damage to many
Scientific knowledge and values. environments on a global scale.
3- Earth as a System
1-Human Population Growth
The earth system is itself an integrated system, but it can be subdivided into four main components, sub-
The number one environmental problem is the ever-growing human population. For most of human history, systems or spheres: the geosphere, atmosphere, hydrosphere and biosphere. These components are also
our numbers were small, as was our impact on Earth. With the advent of agriculture, sanitation, modern systems in their own right and they are tightly interconnected. The four main components of the earth system
medicine and especially, inexpensive energy sources, such as oil, we have proliferated to the point where our may be described briefly in the following way.
numbers are a problem. The total environmental impact from people is estimated by the impact per person
multiplied by the total number people. Therefore, as population increases, more resources are needed and The geosphere - this is the part of the planet composed of rock and minerals; it includes the solid crust, the
given our present technology, greater environmental disruption results. molten mantle and the liquid and solid parts of the earth's core. In many places, the geosphere develops a layer
of soil in which nutrients become available to living organisms, and which thus provides an important
Factors in population change ecological habitat and the basis of many forms of life. The surface of the geosphere is subject to processes of
erosion, weathering and transport, as well as to tectonic forces and volcanic activity, which result in the
Rates of birth, death, and migration determine whether a population grows, shrinks, or remains stable. Birth formation of landforms such as mountains, hills and plateaux.
and immigration add individuals. Death and emigration remove individuals. Technological advances cause
decreased deaths. The increased gap between birth and death rates resulted in population expansion. Natural The atmosphere - this is the gaseous layer surrounding the earth and held to its surface by gravity. The
rate of population change: change due to birth and death rates alone, excluding migration atmosphere receives energy from solar radiation which warms the earth's surface and is re-emitted and
conducted to the atmosphere. The atmosphere also absorbs water from the earth's surface via the process of
evaporation; it then acts to redistribute heat and moisture across the earth's surface. In addition, the atmosphere
contains substances that are essential for life, including carbon, nitrogen, oxygen and hydrogen.
The hydrosphere - this consists of those parts of the earth system composed of water in its liquid, gaseous
(vapour) and solid (ice) phases. The hydrosphere includes: the earth's oceans and seas; its ice sheets, sea ice
and glaciers; its lakes, rivers and streams; its atmospheric moisture and ice crystals; and its areas of permafrost.
The hydrosphere includes both saltwater and freshwater systems, and it also includes the moisture found in
the soil (soil water) and within rocks (groundwater). Water is essential for the existence and maintenance of
3 4
,life on earth. In some classifications, the hydrosphere is sub-divided into the fluid water systems and the 5-Scientific Knowledge and Values
cryosphere (the ice systems).
The results of scientific inquiry to solve a particular environmental problem often provide a series of potential
The biosphere - this contains all living organisms and it is intimately related to the other three spheres: most solutions consistent with the scientific finding. The chosen solution is a reflection of our value system. Fig.4
living organisms require gases from the atmosphere, water from the hydrosphere and nutrients and minerals Science the steps in the scientific method
from the geosphere. Living organisms also require a medium for life, and are adapted to inhabit one or more
of the other three spheres. However, much of the biosphere is contained within a shallow surface layer
encompassing the lower part of the atmosphere, the surface of the geosphere and approximately the upper 100
metres of the ocean. Humans are part of the biosphere, although they are increasingly responsible for the
creation of systems that may be largely artificial (such as cities).
The Earth System and its Components
The main components of the earth system are interconnected by flows (also known as pathways or fluxes)
of energy and materials. The most important flows in the earth system are those concerned with the transfer
of energy and the cycling of key materials in biogeochemical cycles.
Energy flows in environment
The earth is a vast, complex system powered by two sources of energy: an internal source (the decay of
radioactive elements in the geosphere, which generates geothermal heat) and an external source (the solar
radiation received from the Sun); the vast majority of the energy in the earth system comes from the Sun.
Whilst some variations in these two sources occur, their energy supplies are relatively constant and they power
all of the planet's environmental systems. Indeed, energy both drives and flows through environmental
systems, and energy pathways may be highly complex and difficult to identify. For instance, energy may take
the form of latent heat which is absorbed or released when substances change state (for example, between the
liquid and gaseous phases). An example of energy flow and transformation through an ecosystem is illustrated
in Fig.2 Energy is transferred within and between environmental systems in three main ways: radiation - this
is the process by which energy is transmitted through space, typically in the form of electromagnetic waves
convection - this is the physical movement of fluids (such as water or air) that contain energy in the form of
heat; convection does not occur in solids
conduction - this is the transfer of energy in the form of heat through the substance of a medium (from
molecule to molecule)
4- Hazardous Earth Process
There have always been earth processes that are hazardous to people. These natural hazards (such as storms,
floods, earthquakes, landslides and volcanic eruptions) must be recognized and avoided when possible, and
their threat to human life and property must be minimized.
Natural hazardous that produce disasters are becoming super disasters called Catastrophes. An emerging
principle concerning natural hazardous is that, as a result of human activity (e.g. population increase and
changing the land through agriculture, logging, mining, urbanization) what are formerly disasters are
becoming catastrophes. For example: Fig.4 Science the steps in the scientific method
- Human population increase has forced more people to live in hazardous areas, such as in floodplains,
on steep slopes (where landslides are more likely), and near volcanoes. Scope, objectives and aims
- Land-use transformations, including urbanization and deforestation, increase runoff and flood hazard
and may weaken slopes, making landslides more likely.
Environmental geology is a multidisciplinary field of applied science that involves the study of the interaction
- Burning vast amounts of oil, gas and coal has increased the concentration of carbon dioxide in the of humans with the geologic environment including the biosphere, the lithosphere, the hydrosphere, and the
atmosphere, contributing to warming the atmosphere and oceans. As a result, more energy is fed into
atmosphere.
hurricanes. The number of hurricanes has not increased, but the intensity and size of the storms have
increased. The field of environmental geology includes, but is in no way restricted to: 1) the study of the structure and
processes of the earth, mineral, and rocks, especially those that are near-surface or have some significant effect
upon humans, 2) the study of natural hazards and disasters, including defining and mitigation (or adaptation)
of human exposure and threat, 3) managing industrial and domestic waste disposal and minimizing or
eliminating effects of pollution, and 4) managing safe and environmentally responsible stewardship of
geological resources, including minerals, fossil fuels, and water and land use. This course is designed to give
5 6
,the student basic understanding of the processes and materials of the earth and relate these concepts/products • Thermal pollution is caused by the release of heat (thermal energy) into the environment, which results
to human activities. in ecological stress because species vary in their tolerance of temperature extremes. Thermal stress
may occur at natural springs and submarine vents where geologically heated water is emitted. It is also
Dimensions of environmental stress
associated with discharges of hot water from power plants.
What is environmental stress? • Radiation stress is caused by excessive exposure to ionizing energy. The radiation may be emitted by
nuclear waste or explosions, or it can be diagnostic X-rays or solar ultraviolet energy.
Environmental stress is the deviation in environmental conditions from species optima, for example, in • Climatic stress is associated with insufficient or excessive regimes of temperature, moisture, solar
pH, salinity, or temperature.
radiation, wind, or combinations of these.
Environmental stressors (stressors) are factors whose influence is to constrain productivity, reproductive
• Biological stressors are associated with interactions occurring among organisms, such as competition,
success, and ecosystem development . To some degree, stressors affect all organisms as well as their
herbivory, predation, parasitism, and disease. For example, individuals of the same or different species
populations, communities, and ecoscapes (landscapes and seascapes). Stressors may be natural in origin, being
may compete for essential resources that are limited in supply. Herbivory, predation, parasitism, and
associated with such environmental influences as: competition, predation, disease, and other interactions
disease are trophic interactions, in which one species exploits another. Exploitation can be
among organisms constraints related to climate or to inadequate or excessive nutrients, moisture, or space
anthropogenic, as when humans harvest wild animals or trees, or it can be natural, perhaps associated
disturbances such as wildfire and windstorms
with defoliating insects or disease-causing pathogens.
The effects of natural stressors are not always negative. Some individuals, populations, and communities may • Biological pollution occurs when people release organisms beyond their natural range. This might
benefit from the effects of natural stress, even while others suffer a degree of damage. involve the introduction of alien species that invade and alter natural habitats, or it may be the release
of pathogens into the environment through discharges of raw sewage.
Increasingly, however, stressors associated with human activities are the most critical influence on species
and ecosystems. In too many cases, anthropogenic stressors are causing important damage to resources that
are needed to sustain people and their economy, and also to natural biodiversity and ecosystems.
Contamination and Pollution
Environmental stressors may occur as an intense, short-lived event of destruction, also known as a disturbance.
Alternatively, stressors may exert their influence over an extended period of time – that is, in a chronic manner. Pollution is caused by an exposure to chemicals or energy at an intensity that exceeds the tolerance of
The interaction of organisms with a stressor at a particular place and time is called exposure. Exposure can be organisms. As such, pollution is judged to have occurred when it can be shown that organisms have suffered
instantaneous or it may accumulate over time. If an exposure is intense enough, it will cause some sort of toxicity, or other kinds of ecological damage can be demonstrated. Pollution can affect humans and other
species, as well as communities and ecoscapes. Pollution is often caused by an exposure to chemicals in large
biological or ecological change, called a response, to occur. It is important to understand, however, that
enough concentrations to poison at least some organisms. However, pollution can also be caused by non-toxic
individuals, populations, and communities are capable of tolerating a range of intensity of stressors without
exposures, such as the excessive fertilization of a waterbody, a release of waste heat into the environment, or
suffering significant damage.
the discharge of raw sewage containing pathogens.
Damage occurs when one or more stressors elicit responses that can be interpreted as a degradation of
environmental quality. Such responses may include illness or death caused by an exposure of wild animals to Contamination refers to those much more common situations in which potentially damaging stressors are
present in the environment, but at an intensity too low to cause measureable damage. For instance, a certain
pesticides, or as a reduction of the productivity of ecosystems, or the endangerment of vulnerable elements of
biodiversity. In this chapter, we examine a conceptual framework for the study of damage caused by stressors. chemical may occur in a higher concentration than is normally encountered in the environment. However, if
its concentration is too low to cause measurable toxicity to at least some organisms, or to affect other
In the following 11 chapters, we deal with specific kinds of stressors and examine case studies of the kind of
damage they may cause to occur. ecological components or processes, the chemical is a contaminant rather than a pollutant.
Kinds of Stressors Pollution Can Be Natural
Pollution is not only caused by human activities – in some cases, it is a purely natural phenomenon. “Natural”
The diverse kinds of environmental stressors are grouped into classes, although they are not entirely exclusive.
sources of pollution include emissions of particulates and gases such as sulphur dioxide from volcanoes, seeps
• Physical stress is a disturbance in which there is an intense exposure to kinetic energy, which causes of petroleum on the ocean floor, high concentrations of metals in certain soils and rocks, and the heat of
damage to habitats and ecosystems. Examples include such disruptive events as a hurricane or tornado, geothermal springs. Natural pollution may cause severe ecological changes (which humans may view as being
a seismic sea wave (tsunami), the blast of a volcanic eruption, an explosion, or trampling by heavy a kind of damage). The effects can be as intense as those caused by anthropogenic pollution. Nevertheless,
machinery or hikers. although the fact of natural pollution is interesting and well recognized, it does not justify human activities
• Wildfire is another disturbance, which involves the uncontrolled combustion of the biomass of an that cause similar kinds of damage.
ecosystem. A wildfire can be ignited by people, or naturally by lightning. A severe fire consumes much
Anthropogenic Pollution
of the biomass of an ecosystem, but even a less-severe wildfire may kill many organisms by scorching
and poisoning by toxic gases. In the modern world, an enormous amount of pollution is associated with human activities. This has caused
• Chemical pollution occurs when one or more substances occur in a concentration high enough to elicit important damage to human health and to managed and natural ecosystems. People cause pollution in diverse
physiological responses in organisms, potentially causing toxicity and ecological change. Chemical ways, and we examine them in following chapters. Most commonly, anthropogenic pollution is associated
stressors include pesticides, gases such as ozone and sulphur dioxide, and toxic elements such as with these kinds of activities:
arsenic and mercury. Pollution may also be caused by excessive nutrients, which can distort
productivity and other ecological functions. Note that the mere presence of a potentially toxic agent
does not necessarily cause pollution. (The distinction between contamination and pollution is accidental or deliberate emissions of chemicals into the environment, such as sulphur dioxide, metals,
examined later in this chapter.) pesticides, and petroleum releases of substances that react in the environment to synthesize chemicals of
7 8
, greater toxicity – this is known as secondary pollution (as occurs when ozone is created by photochemical Structure and Function of an Ecosystem:
reactions in the atmosphere)emissions of chemicals that degrade stratospheric ozone, such as
Each ecosystem has two main components:
chlorofluorocarbons releases of waste industrial heat, as when a power plant discharges hot water into a river
or lake discharges of nutrient-laden sewage or fertilizer into waterbodies emissions of greenhouse gases that • Abiotic
threaten global climate releases of alien species that cause damage when they invade managed or natural • Biotic
habitats, or are pathogens of people, crops, or native species
Disturbance
A disturbance is an episodic but intense disruption that causes severe biological and ecological damage. An
event of disturbance is followed by a sometimes lengthy period of ecological recovery through the process
known as succession. There are two broad types of disturbances: community-replacing disturbances and
microdisturbances.
Natural Disturbance
Disturbance is a natural force that affects all ecosystems. For example, a wildfire may kill mature trees over a
large area, but that event of destruction is followed by regeneration through succession. Fire is common in the
boreal forest and in drought-prone ecosystems such as prairie and savannah. On average, about 2-million
hectares of forest burns each year in Canada, mostly in fires started by lightning. Wildfire transforms the
habitat conditions and also causes severe pollution by the emission of particulates and gases such as carbon (1) Abiotic components (Nonliving): The abiotic component can be grouped into following categories:-
dioxide and nitrogen oxides to the atmosphere.
(a) Climatic Factors: Which include rain, temperature, light, wind, humidity etc.
Other natural agents of disturbance include hurricanes, tornadoes, floods, and even glaciation (over geological (b) Edaphic Factors: Which include soil, pH, topography minerals etc.
time). These also cause large-scale ecological damage, which is followed by successional recovery. After
glaciation, which involves prolonged burial and abrasion of the land by an enormous mass of ice, the post- The functions of important factors in abiotic components are given below:
melting recovery is initiated by immigrating organisms that colonize the raw landscape.
Soils are much more complex than simple sediments. They contain a mixture of weathered rock fragments,
A volcanic eruption or earthquake can generate one or more devastating oceanic waves, or tsunamis. highly altered soil mineral particles, organic mat-ter, and living organisms. Soils provide nutrients, water,
a home, and a struc-tural growing medium for organisms. The vegetation found growing on top of a soil is
A volcanic eruption can also emit huge amounts of sulphur dioxide, particulates, and other pollutants high closely linked to this component of an ecosystem through nutrient cycling.
into the atmosphere. This natural SO2 contributes to the acidification of precipitation and to other
environmental damage . The atmosphere provides organisms found within ecosystems with carbon di-oxide for photosynthesis and
oxygen for respiration. The processes of evapora-tion, transpiration and precipitation cycle water between
Natural population outbreaks (irruptions) of herbivores, predators, or pathogens can also result in intense the atmosphere and the Earth’s surface.
damage to natural habitats.
Solar radiation is used in ecosystems to heat the atmosphere and to evapo-rate and transpire water into the
Microdisturbances are also a common feature of natural ecosystems. Examples of these smaller-scale atmosphere. Sunlight is also necessary for photosynthesis. Photosynthesis provides the energy for plant
disturbances include the deaths of individual large trees within an otherwise intact forest, perhaps caused by growth and me-tabolism, and the organic food for other forms of life.
disease or an accident (such as a lightning strike). This creates a natural gap in the canopy, beneath which a
microsuccession occurs as plants compete to take advantage of temporary resource opportunities such as extra Most living tissue is composed of a very high percentage of water, up to and even exceeding 90%. The
light. The foliage of mature trees eventually fills the gap. Similarly, the death of an individual coral head protoplasm of a very few cells can survive if their water content drops below 10%, and most are killed if it
within an otherwise intact reef initiates a microsuccession within that marine ecosystem. is less than 30-50%.
Ecological perspective of environment – Concepts of ecosystem – Earth’s major ecosystem, terrestrial Water is the medium by which mineral nutrients enter and are trans-located in plants. It is also necessary
and aquatic. for the maintenance of leaf turgidity and is required for photosynthetic chemical reactions. Plants and
animals receive their water from the Earth’s surface and soil. The original source of this water is precipita-
Living organisms cannot live isolated from their non-living environment be-cause the latter provides tion from the atmosphere.
materials and energy for the survival of the former i.e. there is interaction between a biotic community and
its environment to produce a stable system; a natural self-sufficient unit which is known as an (2) Biotic components:The living organisms including plants, animals and micro-organisms (Bacteria and
ecosystem.Ecosystem are the parts of nature where living orgaisms interact among themselves and with Fungi) that are present in an ecosystem form the biotic components.
their physical environment.
(A) Producers:
The term ‘ecosystem’ was coined by A.G. Tansley, an English botanist, in 1935. An ecosystem is the
The green plants have chlorophyll with the help of which they trap solar energy and change it into chemical
structural and functional unit of ecology (nature) encompassing complex interaction between its biotic
energy of carbohydrates using simple inorganic compounds namely water and carbon dioxide. This process
(living) and abiotic (non-living) components.For example- a pond is a good example of ecosystem. A
is known as photo-synthesis. As the green plants manufacture their own food they are known as Autotrophs
pond, lake, desert, grassland, meadow, forest etc. are common examples of ecosystems.
(i.e. auto = self, trophos = feeder)
9 10
Environmental Geology – fundamental concepts – its scope, objectives and aims – dimensions of 2-Sustainability
environmental stress-scope of environmental geosciences. Ecological perspective of environment – Concepts
of ecosystem – Earth’s major ecosystem, terrestrial and aquatic. Role of geologist in environmental studies. Sustainability is development which ensures that future generations will have equal access to the resources
Status of environmental consciousness in India – EPA. Man and Environment. Geological factors of that our planet offers. Sustainability also refers to types of development that are economically viable, do not
Environmental Health. Need for environmental protection, balancing economic development. Climate change, harm the environment, and are socially just. Sustainability is a long-term concept, something that happens
carbon sequestration and carbon budgeting. over decades or even hundreds of years.
Sustainability related to respect to use of resources is possible for renewable resources such as air and water.
Environmental geology is applied geology. Specifically, it is the use of geologic information to help us solve Sustainability development with respect to nonrenewable resources such as fossil fuels and minerals is
conflicts in land use, to minimize environmental degradation, and to maximize the beneficial results of using possible by:
our natural and modified environments. The application of geology to these problems includes the study of
the following (Fig.1): - Extending their availability through conservation and recycling
- Focusing on when a particular nonrenewable resource is depleted, focusing on how that mineral is
1- Earth materials, such as minerals, rocks, and soils to determine how they form, their potential use as used and developing substitutes for those uses.
resources or waste disposal sites, and their effects on human health
Environmental Crisis?
2- Natural hazards, such as floods, landslides, earthquakes, and volcanic activity, in order to minimize
loss of life and property. Demands made on diminishing resources by a growing human population and the everincreasing production
3- Land for site selection, land use planning, and environmental impact analysis. of human waste have produced what is popularly referred to as the environmental crisis. This crisis in world
4- Hydrologic processes of ground water and surface water resources and water pollution problems. is a result of overpopulation, urbanization, and industrialization, combined with too little ethical for our land
5- Geologic processes, such as deposition of sediment on the ocean floor, the formation of mountains, and inadequate institutions to cope with environmental stress.
and the movement of water on and below the surface of Earth, to evaluate local, regional, and global The rapid use of resources continuous to cause environmental problems on a global scale, including the
change. following:
Fundamental Concepts of Environmental Geology 1- Deforestation and accompanying soil erosion and water and air pollution occur on many continents.
2- Mining of resources, such as metals, coal, and petroleum, whatever they occur produces a variety of
There are main five concepts for studying the environmental geology: environmental problems
1- Human population growth, 2- Sustainability, 3- Earth as a system, 4- Hazardous earth process and 5- 3- Development of both groundwater and surface water resources results in loss of and damage to many
Scientific knowledge and values. environments on a global scale.
3- Earth as a System
1-Human Population Growth
The earth system is itself an integrated system, but it can be subdivided into four main components, sub-
The number one environmental problem is the ever-growing human population. For most of human history, systems or spheres: the geosphere, atmosphere, hydrosphere and biosphere. These components are also
our numbers were small, as was our impact on Earth. With the advent of agriculture, sanitation, modern systems in their own right and they are tightly interconnected. The four main components of the earth system
medicine and especially, inexpensive energy sources, such as oil, we have proliferated to the point where our may be described briefly in the following way.
numbers are a problem. The total environmental impact from people is estimated by the impact per person
multiplied by the total number people. Therefore, as population increases, more resources are needed and The geosphere - this is the part of the planet composed of rock and minerals; it includes the solid crust, the
given our present technology, greater environmental disruption results. molten mantle and the liquid and solid parts of the earth's core. In many places, the geosphere develops a layer
of soil in which nutrients become available to living organisms, and which thus provides an important
Factors in population change ecological habitat and the basis of many forms of life. The surface of the geosphere is subject to processes of
erosion, weathering and transport, as well as to tectonic forces and volcanic activity, which result in the
Rates of birth, death, and migration determine whether a population grows, shrinks, or remains stable. Birth formation of landforms such as mountains, hills and plateaux.
and immigration add individuals. Death and emigration remove individuals. Technological advances cause
decreased deaths. The increased gap between birth and death rates resulted in population expansion. Natural The atmosphere - this is the gaseous layer surrounding the earth and held to its surface by gravity. The
rate of population change: change due to birth and death rates alone, excluding migration atmosphere receives energy from solar radiation which warms the earth's surface and is re-emitted and
conducted to the atmosphere. The atmosphere also absorbs water from the earth's surface via the process of
evaporation; it then acts to redistribute heat and moisture across the earth's surface. In addition, the atmosphere
contains substances that are essential for life, including carbon, nitrogen, oxygen and hydrogen.
The hydrosphere - this consists of those parts of the earth system composed of water in its liquid, gaseous
(vapour) and solid (ice) phases. The hydrosphere includes: the earth's oceans and seas; its ice sheets, sea ice
and glaciers; its lakes, rivers and streams; its atmospheric moisture and ice crystals; and its areas of permafrost.
The hydrosphere includes both saltwater and freshwater systems, and it also includes the moisture found in
the soil (soil water) and within rocks (groundwater). Water is essential for the existence and maintenance of
3 4
,life on earth. In some classifications, the hydrosphere is sub-divided into the fluid water systems and the 5-Scientific Knowledge and Values
cryosphere (the ice systems).
The results of scientific inquiry to solve a particular environmental problem often provide a series of potential
The biosphere - this contains all living organisms and it is intimately related to the other three spheres: most solutions consistent with the scientific finding. The chosen solution is a reflection of our value system. Fig.4
living organisms require gases from the atmosphere, water from the hydrosphere and nutrients and minerals Science the steps in the scientific method
from the geosphere. Living organisms also require a medium for life, and are adapted to inhabit one or more
of the other three spheres. However, much of the biosphere is contained within a shallow surface layer
encompassing the lower part of the atmosphere, the surface of the geosphere and approximately the upper 100
metres of the ocean. Humans are part of the biosphere, although they are increasingly responsible for the
creation of systems that may be largely artificial (such as cities).
The Earth System and its Components
The main components of the earth system are interconnected by flows (also known as pathways or fluxes)
of energy and materials. The most important flows in the earth system are those concerned with the transfer
of energy and the cycling of key materials in biogeochemical cycles.
Energy flows in environment
The earth is a vast, complex system powered by two sources of energy: an internal source (the decay of
radioactive elements in the geosphere, which generates geothermal heat) and an external source (the solar
radiation received from the Sun); the vast majority of the energy in the earth system comes from the Sun.
Whilst some variations in these two sources occur, their energy supplies are relatively constant and they power
all of the planet's environmental systems. Indeed, energy both drives and flows through environmental
systems, and energy pathways may be highly complex and difficult to identify. For instance, energy may take
the form of latent heat which is absorbed or released when substances change state (for example, between the
liquid and gaseous phases). An example of energy flow and transformation through an ecosystem is illustrated
in Fig.2 Energy is transferred within and between environmental systems in three main ways: radiation - this
is the process by which energy is transmitted through space, typically in the form of electromagnetic waves
convection - this is the physical movement of fluids (such as water or air) that contain energy in the form of
heat; convection does not occur in solids
conduction - this is the transfer of energy in the form of heat through the substance of a medium (from
molecule to molecule)
4- Hazardous Earth Process
There have always been earth processes that are hazardous to people. These natural hazards (such as storms,
floods, earthquakes, landslides and volcanic eruptions) must be recognized and avoided when possible, and
their threat to human life and property must be minimized.
Natural hazardous that produce disasters are becoming super disasters called Catastrophes. An emerging
principle concerning natural hazardous is that, as a result of human activity (e.g. population increase and
changing the land through agriculture, logging, mining, urbanization) what are formerly disasters are
becoming catastrophes. For example: Fig.4 Science the steps in the scientific method
- Human population increase has forced more people to live in hazardous areas, such as in floodplains,
on steep slopes (where landslides are more likely), and near volcanoes. Scope, objectives and aims
- Land-use transformations, including urbanization and deforestation, increase runoff and flood hazard
and may weaken slopes, making landslides more likely.
Environmental geology is a multidisciplinary field of applied science that involves the study of the interaction
- Burning vast amounts of oil, gas and coal has increased the concentration of carbon dioxide in the of humans with the geologic environment including the biosphere, the lithosphere, the hydrosphere, and the
atmosphere, contributing to warming the atmosphere and oceans. As a result, more energy is fed into
atmosphere.
hurricanes. The number of hurricanes has not increased, but the intensity and size of the storms have
increased. The field of environmental geology includes, but is in no way restricted to: 1) the study of the structure and
processes of the earth, mineral, and rocks, especially those that are near-surface or have some significant effect
upon humans, 2) the study of natural hazards and disasters, including defining and mitigation (or adaptation)
of human exposure and threat, 3) managing industrial and domestic waste disposal and minimizing or
eliminating effects of pollution, and 4) managing safe and environmentally responsible stewardship of
geological resources, including minerals, fossil fuels, and water and land use. This course is designed to give
5 6
,the student basic understanding of the processes and materials of the earth and relate these concepts/products • Thermal pollution is caused by the release of heat (thermal energy) into the environment, which results
to human activities. in ecological stress because species vary in their tolerance of temperature extremes. Thermal stress
may occur at natural springs and submarine vents where geologically heated water is emitted. It is also
Dimensions of environmental stress
associated with discharges of hot water from power plants.
What is environmental stress? • Radiation stress is caused by excessive exposure to ionizing energy. The radiation may be emitted by
nuclear waste or explosions, or it can be diagnostic X-rays or solar ultraviolet energy.
Environmental stress is the deviation in environmental conditions from species optima, for example, in • Climatic stress is associated with insufficient or excessive regimes of temperature, moisture, solar
pH, salinity, or temperature.
radiation, wind, or combinations of these.
Environmental stressors (stressors) are factors whose influence is to constrain productivity, reproductive
• Biological stressors are associated with interactions occurring among organisms, such as competition,
success, and ecosystem development . To some degree, stressors affect all organisms as well as their
herbivory, predation, parasitism, and disease. For example, individuals of the same or different species
populations, communities, and ecoscapes (landscapes and seascapes). Stressors may be natural in origin, being
may compete for essential resources that are limited in supply. Herbivory, predation, parasitism, and
associated with such environmental influences as: competition, predation, disease, and other interactions
disease are trophic interactions, in which one species exploits another. Exploitation can be
among organisms constraints related to climate or to inadequate or excessive nutrients, moisture, or space
anthropogenic, as when humans harvest wild animals or trees, or it can be natural, perhaps associated
disturbances such as wildfire and windstorms
with defoliating insects or disease-causing pathogens.
The effects of natural stressors are not always negative. Some individuals, populations, and communities may • Biological pollution occurs when people release organisms beyond their natural range. This might
benefit from the effects of natural stress, even while others suffer a degree of damage. involve the introduction of alien species that invade and alter natural habitats, or it may be the release
of pathogens into the environment through discharges of raw sewage.
Increasingly, however, stressors associated with human activities are the most critical influence on species
and ecosystems. In too many cases, anthropogenic stressors are causing important damage to resources that
are needed to sustain people and their economy, and also to natural biodiversity and ecosystems.
Contamination and Pollution
Environmental stressors may occur as an intense, short-lived event of destruction, also known as a disturbance.
Alternatively, stressors may exert their influence over an extended period of time – that is, in a chronic manner. Pollution is caused by an exposure to chemicals or energy at an intensity that exceeds the tolerance of
The interaction of organisms with a stressor at a particular place and time is called exposure. Exposure can be organisms. As such, pollution is judged to have occurred when it can be shown that organisms have suffered
instantaneous or it may accumulate over time. If an exposure is intense enough, it will cause some sort of toxicity, or other kinds of ecological damage can be demonstrated. Pollution can affect humans and other
species, as well as communities and ecoscapes. Pollution is often caused by an exposure to chemicals in large
biological or ecological change, called a response, to occur. It is important to understand, however, that
enough concentrations to poison at least some organisms. However, pollution can also be caused by non-toxic
individuals, populations, and communities are capable of tolerating a range of intensity of stressors without
exposures, such as the excessive fertilization of a waterbody, a release of waste heat into the environment, or
suffering significant damage.
the discharge of raw sewage containing pathogens.
Damage occurs when one or more stressors elicit responses that can be interpreted as a degradation of
environmental quality. Such responses may include illness or death caused by an exposure of wild animals to Contamination refers to those much more common situations in which potentially damaging stressors are
present in the environment, but at an intensity too low to cause measureable damage. For instance, a certain
pesticides, or as a reduction of the productivity of ecosystems, or the endangerment of vulnerable elements of
biodiversity. In this chapter, we examine a conceptual framework for the study of damage caused by stressors. chemical may occur in a higher concentration than is normally encountered in the environment. However, if
its concentration is too low to cause measurable toxicity to at least some organisms, or to affect other
In the following 11 chapters, we deal with specific kinds of stressors and examine case studies of the kind of
damage they may cause to occur. ecological components or processes, the chemical is a contaminant rather than a pollutant.
Kinds of Stressors Pollution Can Be Natural
Pollution is not only caused by human activities – in some cases, it is a purely natural phenomenon. “Natural”
The diverse kinds of environmental stressors are grouped into classes, although they are not entirely exclusive.
sources of pollution include emissions of particulates and gases such as sulphur dioxide from volcanoes, seeps
• Physical stress is a disturbance in which there is an intense exposure to kinetic energy, which causes of petroleum on the ocean floor, high concentrations of metals in certain soils and rocks, and the heat of
damage to habitats and ecosystems. Examples include such disruptive events as a hurricane or tornado, geothermal springs. Natural pollution may cause severe ecological changes (which humans may view as being
a seismic sea wave (tsunami), the blast of a volcanic eruption, an explosion, or trampling by heavy a kind of damage). The effects can be as intense as those caused by anthropogenic pollution. Nevertheless,
machinery or hikers. although the fact of natural pollution is interesting and well recognized, it does not justify human activities
• Wildfire is another disturbance, which involves the uncontrolled combustion of the biomass of an that cause similar kinds of damage.
ecosystem. A wildfire can be ignited by people, or naturally by lightning. A severe fire consumes much
Anthropogenic Pollution
of the biomass of an ecosystem, but even a less-severe wildfire may kill many organisms by scorching
and poisoning by toxic gases. In the modern world, an enormous amount of pollution is associated with human activities. This has caused
• Chemical pollution occurs when one or more substances occur in a concentration high enough to elicit important damage to human health and to managed and natural ecosystems. People cause pollution in diverse
physiological responses in organisms, potentially causing toxicity and ecological change. Chemical ways, and we examine them in following chapters. Most commonly, anthropogenic pollution is associated
stressors include pesticides, gases such as ozone and sulphur dioxide, and toxic elements such as with these kinds of activities:
arsenic and mercury. Pollution may also be caused by excessive nutrients, which can distort
productivity and other ecological functions. Note that the mere presence of a potentially toxic agent
does not necessarily cause pollution. (The distinction between contamination and pollution is accidental or deliberate emissions of chemicals into the environment, such as sulphur dioxide, metals,
examined later in this chapter.) pesticides, and petroleum releases of substances that react in the environment to synthesize chemicals of
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, greater toxicity – this is known as secondary pollution (as occurs when ozone is created by photochemical Structure and Function of an Ecosystem:
reactions in the atmosphere)emissions of chemicals that degrade stratospheric ozone, such as
Each ecosystem has two main components:
chlorofluorocarbons releases of waste industrial heat, as when a power plant discharges hot water into a river
or lake discharges of nutrient-laden sewage or fertilizer into waterbodies emissions of greenhouse gases that • Abiotic
threaten global climate releases of alien species that cause damage when they invade managed or natural • Biotic
habitats, or are pathogens of people, crops, or native species
Disturbance
A disturbance is an episodic but intense disruption that causes severe biological and ecological damage. An
event of disturbance is followed by a sometimes lengthy period of ecological recovery through the process
known as succession. There are two broad types of disturbances: community-replacing disturbances and
microdisturbances.
Natural Disturbance
Disturbance is a natural force that affects all ecosystems. For example, a wildfire may kill mature trees over a
large area, but that event of destruction is followed by regeneration through succession. Fire is common in the
boreal forest and in drought-prone ecosystems such as prairie and savannah. On average, about 2-million
hectares of forest burns each year in Canada, mostly in fires started by lightning. Wildfire transforms the
habitat conditions and also causes severe pollution by the emission of particulates and gases such as carbon (1) Abiotic components (Nonliving): The abiotic component can be grouped into following categories:-
dioxide and nitrogen oxides to the atmosphere.
(a) Climatic Factors: Which include rain, temperature, light, wind, humidity etc.
Other natural agents of disturbance include hurricanes, tornadoes, floods, and even glaciation (over geological (b) Edaphic Factors: Which include soil, pH, topography minerals etc.
time). These also cause large-scale ecological damage, which is followed by successional recovery. After
glaciation, which involves prolonged burial and abrasion of the land by an enormous mass of ice, the post- The functions of important factors in abiotic components are given below:
melting recovery is initiated by immigrating organisms that colonize the raw landscape.
Soils are much more complex than simple sediments. They contain a mixture of weathered rock fragments,
A volcanic eruption or earthquake can generate one or more devastating oceanic waves, or tsunamis. highly altered soil mineral particles, organic mat-ter, and living organisms. Soils provide nutrients, water,
a home, and a struc-tural growing medium for organisms. The vegetation found growing on top of a soil is
A volcanic eruption can also emit huge amounts of sulphur dioxide, particulates, and other pollutants high closely linked to this component of an ecosystem through nutrient cycling.
into the atmosphere. This natural SO2 contributes to the acidification of precipitation and to other
environmental damage . The atmosphere provides organisms found within ecosystems with carbon di-oxide for photosynthesis and
oxygen for respiration. The processes of evapora-tion, transpiration and precipitation cycle water between
Natural population outbreaks (irruptions) of herbivores, predators, or pathogens can also result in intense the atmosphere and the Earth’s surface.
damage to natural habitats.
Solar radiation is used in ecosystems to heat the atmosphere and to evapo-rate and transpire water into the
Microdisturbances are also a common feature of natural ecosystems. Examples of these smaller-scale atmosphere. Sunlight is also necessary for photosynthesis. Photosynthesis provides the energy for plant
disturbances include the deaths of individual large trees within an otherwise intact forest, perhaps caused by growth and me-tabolism, and the organic food for other forms of life.
disease or an accident (such as a lightning strike). This creates a natural gap in the canopy, beneath which a
microsuccession occurs as plants compete to take advantage of temporary resource opportunities such as extra Most living tissue is composed of a very high percentage of water, up to and even exceeding 90%. The
light. The foliage of mature trees eventually fills the gap. Similarly, the death of an individual coral head protoplasm of a very few cells can survive if their water content drops below 10%, and most are killed if it
within an otherwise intact reef initiates a microsuccession within that marine ecosystem. is less than 30-50%.
Ecological perspective of environment – Concepts of ecosystem – Earth’s major ecosystem, terrestrial Water is the medium by which mineral nutrients enter and are trans-located in plants. It is also necessary
and aquatic. for the maintenance of leaf turgidity and is required for photosynthetic chemical reactions. Plants and
animals receive their water from the Earth’s surface and soil. The original source of this water is precipita-
Living organisms cannot live isolated from their non-living environment be-cause the latter provides tion from the atmosphere.
materials and energy for the survival of the former i.e. there is interaction between a biotic community and
its environment to produce a stable system; a natural self-sufficient unit which is known as an (2) Biotic components:The living organisms including plants, animals and micro-organisms (Bacteria and
ecosystem.Ecosystem are the parts of nature where living orgaisms interact among themselves and with Fungi) that are present in an ecosystem form the biotic components.
their physical environment.
(A) Producers:
The term ‘ecosystem’ was coined by A.G. Tansley, an English botanist, in 1935. An ecosystem is the
The green plants have chlorophyll with the help of which they trap solar energy and change it into chemical
structural and functional unit of ecology (nature) encompassing complex interaction between its biotic
energy of carbohydrates using simple inorganic compounds namely water and carbon dioxide. This process
(living) and abiotic (non-living) components.For example- a pond is a good example of ecosystem. A
is known as photo-synthesis. As the green plants manufacture their own food they are known as Autotrophs
pond, lake, desert, grassland, meadow, forest etc. are common examples of ecosystems.
(i.e. auto = self, trophos = feeder)
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