Environmental Science

Introduction to Environmental Science and Engineering

• The module presents the definition of terms related to the study of Environmental Science and Engineering
• It enumerates and explains the scope of the environment.
• It differentiates environmental science from environmental engineering.

Science of the Environment

• The science of environment is a multi-disciplinary science, comprising of branches like chemistry, physics, medical science, life science, agriculture, public health, and sanitary engineering.
• It is the science of physical phenomena in the environment.
• It studies the sources, reactions, transport, effect, and fate of physical and biological species in the air, water, and soil, and the effect from human activity upon these.

Environment

• The environment consists of the surrounding external conditions influencing development or growth of people, animals, or plants, including living or working conditions.
• The environment is the interaction between biotic or living organisms and abiotic or non-living things.
• The environment comprises various forces like physical, intellectual, economic, political, cultural, social, moral, and emotional forces.
• The environment is the sum total of all the external forces, influences, and conditions, affecting the life, nature, behavior, growth, development, and maturation of living organisms.

Scope of Enviornment

• The scope of the environment includes the atmosphere, hydrosphere, lithosphere, and biosphere.

The Atmosphere

• Etymology: Greek words: "(1) “atmos” – vapor or air ; (2) "sphere" – ball, globe"
• The atmosphere is the protective blanket of gases surrounding the earth, saving it from the hostile environment of outer space.
• The atmosphere absorbs most cosmic rays and electromagnetic radiation from the sun.
• It transmits ultraviolet, visible, near-infrared radiation (300 to 2500 nanometers), and radio waves (0.14 to 40 meters), while filtering tissue-damaging ultraviolet waves below about 300 nanometers (nm).
• The atmosphere sustains life on earth.

Composition of Earth's Atmosphere

• Nitrogen comprises 78%
• Oxygen makes up 21%
• Other Gases make up about 1%

Layers of Earth's Atmosphere

• The layers from closest to furthest
• Troposphere : 0 to 12-18 km
• Stratosphere : 11 to 50 km
• Mesosphere : 40-50 to 80-90 km
• Thermosphere : 80-90 to 800 km
• Exosphere : 800 to 3000 km

Troposphere

• Reaches 12 km from the Earth's surface
• The thinnest layer of the atmosphere
• Comprises roughly 80% of the weight of the atmosphere

Stratosphere

• Reaches 50 km from the Earth's surface
• The Ozone Layer is here
• Ozone Layer is a protective layer that prevents ultraviolet radiation from directly entering the Earth's surface

Mesosphere

• Extends between 50 km and 70 km from the Earth's surface
• Known to be the coldest layer

Thermosphere

• Contains only 0.001% of the gases in the atmosphere
• Hottest layer of the atmosphere
• The lonosphere, where aurora phenomena occur, is located here

Exosphere

• Outermost layer of the atmosphere
• Extends as far as 6000 miles out into space

The Hydrosphere

• Etymology: Greek words: (1) “hydro" – water ; (2) "sphere" – ball, globe
• The Hydrosphere comprises all types of water resources oceans, seas, lakes, rivers, streams, reservior, polar icecaps, glaciers, and ground water.
• 97% of the earth's water supply is in the oceans.
• About 2% of water resources is locked in polar icecaps and glaciers.
• About 1% is available as fresh surface water-rivers, lakes streams, and ground water fit that is used for human consumption and other uses.

The World's Water Resources

• About 71% of the Earth's surface is water-covered, with oceans making up ~96.5% of all Earth's water
• Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, and in the ground as soil moisture and in aquifers.
• The majority of water on Earth is saline water in the oceans.
• Freshwater resources, such as water falling from the skies and moving into streams, rivers, lakes, and groundwater, provide people with the water they need every day to live.
• There is some 3,100 mi³ (12,900 km³) of water in the atmosphere
• The volume of all water would be about 332.5 million cubic miles (mi³), or 1,386 million cubic kilometers (km³).
• Each day, some 280 mi³ (1,170 km³) of water evaporate or transpire into the atmosphere.
• The surface stores just over 2,000,000 mi³ (8,400,000 km³) of water in the earth

Table of World's Water Resources

• Oceans, Seas, & Bays have the volume of 321,000,000 mi³ & 1,338,000,000 km³
• Ice caps, Glaciers, & Snow have a water volume of 5,773,000mi³ and 24,064,000 km³
• Groundwater has a volume of 5,614,000 mi³ and 23,400,000 km³

The Lithosphere

• Etymology: Greek words: (1) “lithos" – rock, solid rock; (2) "sphere" – ball, globe
• The Lithosphere is the outer part of the solid earth.
• The Lithosphere consists of: the Crust (both oceanic and continental); Lithospheric Mantle or Outermost layer of the mantle (about 60 miles (100 kilometers) in thickness)
• It consists of minerals occurring in the earth's crusts and the soil (e.g. minerals, organic matter, air, and water)

The Biosphere

• Etymology: Greek words: (1) “bios" – life or living ; (2) "sphere" – ball, globe
• The Biosphere indicates the realm of living organisms and their interactions with the environment, via the atmosphere, hydrosphere, and lithosphere.

Enviromental Science

• Science is systematized knowledge derived from and tested by recognition and formulation of a problem, collection of data through observation, and experimentation.
• Social Science deals with the study of people and how they live together.
• Natural Science deals with the study of nature and the physical world, incorporating biology, chemistry, geology, physics, and environmental science.
• Environmental science encompasses all fields of natural science, and is defined as the study of relationships of the natural world, and between organisms and their environment.
• The field integrates physical, biological, and information sciences to study the environment, and find solutions to environmental problems.
• It is the study of living organisms and how they interact with our environment.

Environmental Engineering

• Engineering is a profession that applies science and mathematics to make properties of matter and sources of energy useful in structures, machines, products, systems, and processes.
• Environmental Engineering is the application of science and engineering principles to improve the environment (air, water, and/or land resources), to provide healthful water, air, and land for human habitation, and remediate polluted sites.
• It focuses on protecting people from adverse environmental effects, such as pollution, and improving environmental quality.
• Common environmental engineering problems are the provision of safe water supplies, proper waste disposal or recycling, adequate drainage for sanitation, control of pollution, and the social and environmental impacts of solutions.