CHAPTER 1
The Environment
Part I: Basic Concepts Related to the Environment: Environmental Spheres
1.1 Environmental Chemistry
Environmental chemistry is a branch of chemistry that focuses on the study of chemical processes occurring in the environment, including air, water and soil. It draws upon principles and concepts from various fields such as chemistry, biology, geology, physics, ecology and engineering. Environmental chemistry is concerned with the chemistry of natural processes as well as pollutants and contaminants and their impact on the environment and human health.
Key areas of study in environmental chemistry include atmospheric chemistry, aquatic chemistry, soil chemistry, environmental toxicology and environmental analytical chemistry. Environmental chemists employ a variety of techniques to study chemical processes in the environment, including laboratory experiments, field studies and computer modelling.
The goal of environmental chemistry is to understand the chemical processes occurring in the environment and the impact of human activities on these processes in order to develop strategies to mitigate environmental problems and protect nature and human health.
1.2 The Environment
The environment can be defined as the surroundings or conditions in which an organism, person or group operates. It includes all the physical, biological and social factors that influence the lives of living organisms.
The environment encompasses both natural and human-made elements, such as air, water, land, industry, agricultural and livestock activities, human settlements, infrastructures, etc., constituting a complex system that is constantly changing and interacting with the living and non-living components within it.
The environment is structured into ecosystems. An ecosystem refers to the community of living and non-living things that interact with each other in a specific area. It includes all of the organisms in a particular habitat, along with their physical surroundings, such as air, water and soil. Ecosystems can be small, such as a pond or a forest, or they can be large, such as a desert or an ocean. All living organisms in an ecosystem are interconnected and depend on each other for survival. For example, plants provide oxygen and food for animals, while animals help pollinate plants and disperse seeds. Bacteria and fungi are also important components of ecosystems, breaking down dead matter and recycling nutrients back into the environment.
Human activities can have a significant impact on ecosystems. Pollution, deforestation and climate change are just a few of the ways that human actions can disrupt the delicate balance of an ecosystem. Protecting and preserving ecosystems is important for the health of the planet and all of its inhabitants.
The different parts of the environment that make up the Earth's system are named spheres. These spheres interact with each other and influence the planet's climate, weather patterns and ecosystems.
The environment can be broadly categorised into five spheres, each of which has its own unique characteristics and dynamics:
- Atmosphere: This is the layer of gases that surrounds the Earth. It is composed of different gases, including nitrogen, oxygen and carbon dioxide (CO2), and it protects the Earth from harmful radiation from the sun.
- Hydrosphere: This is the part of the Earth that consists of all water on and under the surface, including oceans, lakes, rivers, groundwater and glaciers.
- Lithosphere: This is the solid part of the Earth's surface, including the continents, rocks and soil.
- Biosphere: This is the part of the Earth that includes all living organisms, including plants, animals and microorganisms.
- Anthroposphere: This refers to the human-made environment, including buildings, cities and infrastructure, and the impact of human activities on other environmental spheres.
1.3 The Atmosphere
The atmosphere (etymology: ?tµ?? (atmos), 'vapor' and s?a??a (sphaira), 'sphere') is the layer of gases that surrounds the Earth and is held in place by the planet's gravitational field.
The Earth's atmosphere is a complex, heterogeneous system that plays several crucial functions. Some of the main functions of the atmosphere include:
- Protection: The atmosphere protects life on Earth from harmful radiation and solar wind from the sun. It also shields the planet from meteoroids, which would otherwise cause widespread destruction upon impact.
- Regulation of temperature: The atmosphere helps regulate the temperature of the planet by trapping heat from the sun and preventing it from escaping into space. This helps keep the planet's temperature within a range that is suitable for life.
- Transportation of heat, moisture and gases: The atmosphere is responsible for transporting heat from the equator to the poles, which helps regulate the global climate. It also transports moisture and gases around the planet, which are essential for life.
- Provision of gases for respiration and photosynthesis: The atmosphere provides oxygen for respiration and carbon dioxide for photosynthesis which are essential for life. It also contains other gases such as nitrogen, which are important for the planet's ecology and the survival of many organisms.
- Support of weather patterns: The atmosphere is the stage on which weather patterns occur. It is responsible for creating and sustaining atmospheric pressure systems, which drive the movement of air masses and cause weather patterns such as hurricanes, tornadoes and thunderstorms.
- Communication: The atmosphere allows for the transmission of radio and television signals, as well as other forms of wireless communication.
The Earth's atmosphere is composed of several major and minor components (Table 1.1).
- Major components: nitrogen (N2), oxygen (O2), argon (Ar).
- Minor components: carbon dioxide (CO2), neon (Ne), helium (He), methane (CH4), krypton (Kr), xenon (Xe), ozone (O3).
The percentage of every single gas represents the volume of this gas in the air. For example, the percentage of 20.95 for oxygen means that for every 100 units of air, 21 units are oxygen.
Water vapour is also a significant component of the atmosphere, but its concentration varies greatly depending on location and weather conditions. It can range from less than 1% in cold, dry regions to over 4% in humid, tropical areas. Additionally, the atmosphere also contains various pollutants and aerosols, which can have significant impacts on air quality and climate.
TABLE 1.1 Components of the atmosphere and their respective percentages
Gas Percentage Nitrogen (N2) 78.08% Oxygen (O2) 20.95% Argon (Ar) 0.93% Carbon dioxide (CO2) 0.04% Neon (Ne) 0.0018 Helium (He) 0.0005% Methane (CH4) 0.0002% Krypton (Kr) 0.0001% Xenon (Xe) Trace amounts Ozone (O3) Trace amounts
Topics of Interest: The Atmospheres of the Solar System's Planets
The atmospheres of the planets in the solar system can vary greatly depending on a number of factors, such as distance from the sun, composition of the planet and the planet's history. Here's a brief overview of the atmospheres of the major planets in our solar system:
- Mercury has a very thin atmosphere consisting mostly of helium and traces of sodium, potassium and oxygen. Its close proximity to the sun causes the solar wind to strip away its atmosphere.
- Venus has a thick, toxic atmosphere composed mainly of carbon dioxide and sulfuric1 acid. The pressure at the surface of Venus is about 90 times that of Earth's atmosphere, which is equivalent to being about 900?m underwater on Earth.
- Earth's atmosphere is composed mainly of nitrogen, oxygen and trace amounts of other gases such as carbon dioxide, methane and O3. This combination of gases is what allows life to thrive on Earth.
- Mars: Mars has a thin atmosphere composed mainly of carbon dioxide. It also has traces of nitrogen and argon, but the atmospheric pressure is only about 1% of that on Earth.
- Jupiter: Jupiter has a very thick atmosphere composed mainly of hydrogen and helium. It also has traces of methane, ammonia and water vapour. Jupiter's atmosphere is known for its swirling bands of clouds and the famous Great Red Spot.
- Saturn's atmosphere is similar to Jupiter's, with hydrogen and helium making up the majority of the atmosphere. Saturn's atmosphere also contains traces of methane, ammonia and water vapour.
- Uranus has a much colder atmosphere than the gas giants Jupiter and...
