Introduction to environmental science

Introduction to
Environmental Science


Environmental Concepts


The environmental system
 The natural environment, commonly referred

to simply as the environment, is a term that
encompasses all living and non-living things
occurring naturally on Earth or some region
thereof.


The environmental system
 The concept of the natural environment can be broken

down into a few key components:
 Complete ecological units that function as natural
systems without massive human intervention,
including all vegetation, animals, microorganisms, soil,
rocks, atmosphere and natural phenomena that occur
within their boundaries.
 Universal natural resources and physical phenomena
that lack clear-cut boundaries, such as air, water, and
climate, as well as energy, radiation, electric charge,
and magnetism, not originating from human activity.

The environmental system
 The environmental system may be understood

in an ecological sense as the set of
interactions between the elements of the
biosphere, which includes the atmosphere, the
hydrosphere, the lithosphere and the
ecosphere.


The environmental system
 The atmosphere is a mixture of nitrogen (78%),

oxygen (21%), and traces (remaining 1%) of carbon
dioxide, argon, water vapor and other components.
 The atmosphere is approximately 1,100 km high, the
stratosphere (10 to 50 km) and the troposphere (less
than 10 km) are the main atmospheric interactors of
the biosphere.
 The atmosphere is a prime mean for the spatial
diffusion of pollutants and a temporary mean of
their accumulation.


The environmental system
 The hydrosphere is the accumulation of water in all its

states (solid, liquid and gas) and the elements dissolved
it in (sodium, magnesium, calcium, chloride and
sulphate).

 97% of the water forms the oceans, 2% is ice (north
and south poles) and 1% forms rivers, lakes, ground
water and atmospheric vapor.
 It covers around 71% of the earth's surface and is an
important accumulator of pollutants and a significant
vector of diffusion.


The environmental system
 The lithosphere is the thin crust between the mantle and the

atmosphere. Although the lithosphere is around 100 km
thick, only 1 km of it can be considered in interaction with
the biosphere.
 Main constituents are oxygen (47%), silicon (28%),
aluminum (8%), iron (5%), calcium (4%), sodium (3%),
potassium (3%) and magnesium (2%) in a crystalline state.
 The lithosphere is the main source of pollutants and a
permanent accumulator. Some are naturally released
through sources like volcanic eruptions, while others like
fossil fuels are the result of artificial extraction and
combustion.


The environmental system
 The ecosphere is the set of all living organisms,

including animals and plants.
 They are temporary accumulators (like lead) and
sources for pollutants (natural forest burning) in a

very complex set of relationships with the
atmosphere, hydrosphere and lithosphere.


The Environmental System


Introduction
 What is an environment?
 What is Environmental Science?


The Environment
 Environment: Circumstances and conditions that

surround an organism or group of organisms. Social
and cultural conditions that affect an individual or
community
 Environment: all the external conditions, both
abiotic and biotic, that affect an organism or group
of organisms.
 Organisms also exert effects on their
environment


Environment: the total of our
surroundings
• All the things around us with which we interact:
• Living things

Animals, plants, forests, fungi, etc.
• Nonliving things
• Continents, oceans, clouds, soil, rocks
• Our built environment
• Buildings, human-created living centers
• Social relationships and institutions
•


Humans and the world around us
 Humans change the environment… in ways not fully

understood
 We depend completely on the environment for survival
 Increased wealth, health, mobility, leisure
time
 But…natural systems have been degraded
 i.e., pollution, erosion and species extinction
 Environmental changes threaten long-term
health and survival
(i.e., id est; (e.g., exempli gratia)


Environmental science - Definition
 Environmental science is the science of the

interactions between the physical, chemical, and
biological components of the environment, including
their effects on all types of organisms.
 Environmental Science: Systematic study of our

environment and our place in it.
 Environmental science includes specific areas of
study, such as: biology, ecology, and environmental
engineering.


 Environmental science is the study of:
 How the natural world works
 How the environment affects humans

and vice versa


HISTRORY OF
ENVIRONMENTAL SCIENCE


Malthus’ Theory


 Context
 Thomas Malthus (1766-1834) in his book

“Essays on the Principle of Population” (1798).
 Relationships between population and food
resources (area under cultivation).
 Growth of available resources is linear while
population growth is often non-linear
(exponential).
 Written during a period of weak harvests.

 Context
 Took notice of famines in the Middle Ages,

especially in the early 14th century (1316).
 From the data he gathered, population was
doubling every 25 years.
 Over a century’s time, population would rise
by a factor of 16 while food rose by a factor of
4.


1. Concept
Malthus’ Theory of Population Growth
 In 1798 Thomas Malthus published his

views on the effect of population on food
supply. His theory has two basic principles:
 Population grows at a geometric rate i.e. 1,
2, 4, 16, 32, etc.
 Food production increases at an arithmetic
rate i.e. 1, 2, 3, 4, etc.


Malthus (cont.)
 The consequence of these
Deficit

DemographicResource

growth
growth

two principles is that
eventually, population
will exceed the capacity
of agriculture to support
the new population
numbers.
 Population would rise
until a limit to growth
was reached.


Malthus (cont.)
 Further growth would be limited when:
 preventive checks - postponement of marriage

(lowering of fertility rate), increased cost of food etc.
 positive checks - famine, war, disease, would increase
the death rate.
 Malthusian ideas are often supported by Western governments

because it highlights the problem of too many mouths to feed,
rather than the uneven distribution of resources;


Malthus (cont.)
Population grows
geometrically….

Population exceeds
carrying capacity…
Population is kept in
“check”– preventative
and/or positive checks