Lesson 5-6: Components of the Environment PDF

LESSON 05-06: COMPONENTS OF THE ENVIRONMENT 3.1. COMPONENTS OF THE ENVIRONMENT Environment is composed of many elements or substances which are called as the components of the environment. The environment is classified into three types. These are physical environment, living (biological)...

LESSON 05-06: COMPONENTS OF THE ENVIRONMENT 3.1. COMPONENTS OF THE ENVIRONMENT Environment is composed of many elements or substances which are called as the components of the environment. The environment is classified into three types. These are physical environment, living (biological) environment and the manmade (social or, cultural) environment. The components are classified into two sections biotic and abiotic components. Basically the abiotic components are found in the physical environment and the biotic components are found in the living environment. These components are found in different regions of the environment which are also called as the compartment of the environment (Fig. 3.1). Figure 3.1: Environmental components (Source: encyclopedia britannica). 3.1.1. Atmosphere: Greek word “Atmo” means vapor or air. It is the envelop of gases that surrounds the earth below 1 m surface to about 10000 km. The atmosphere plays a vital role in maintaining the heat balance on the earth by absorbing the i.r. radiation received from the sun and reemitted by the earth. The atmosphere is the umbrella-like envelope (a thin layer) of gases (mainly 78% of Nitrogen, 21% of Oxygen, 0.93% of Argon, and 0.03% of Carbon dioxide) that covers the outer surface of the planet earth. The other gases are Neon, Helium, Krypton, Xenon, Water vapor, different pollutants, etc (Table 01). 3|Page © 2024 Rahman, SMM  3.1.1.1. Troposphere Lowest layer of the air extending from the sea level to an altitude of 10-16 km humans live in this layer, and 99% of the water vapor exists in this layer All-weather occurs, and most clouds appear here in this layer (Table 02) Table 01: Composition of the atmosphere. Name of Gas Composition by Volume Nitrogen (N2) 78.08% Oxygen (O2) 20.95% Argon (Ar) 0.93% Carbon Dioxide (CO2) 0.03% Neon (Ne) 0.001% Helium (He) 0.0005% Krypton (Kr) 0.0001% Xenon (Xe) 0.00009% Hydrogen (H2) 0.00005% Methane (CH4) 0.00002% Nitrous oxide (N2O) 0.00005% 3.1.1.2. Stratosphere It’s the layer above the troposphere that extends up to 50 km of the sea level With increasing of altitude, the temperature rises to a max. of – 2 0C (Fig. 3.2) The ozone layer can be found in this layer (Table 02) 3.1.1.3. Mesosphere It’s the layer above the stratosphere that extends up to 80 km of the sea level Absence of high-level radiation species causes temperature decrease to – 90 0C Most meteors burn up in this layer (Table 02) Table 02: Characteristics of the major layers of the atmosphere. Atmospheric Height Above the Temperature Range Major chemical Layer Sea Level ˚C species Troposphere 0 to 11 15 to -56 O2, N2, CO2, H2O Stratosphere 11 to 50 -56 to -2 O3 Mesosphere 50 to 85 -2 to -92 O2 , NO+ + Thermosphere 85 to 500 -92 to 1200 O2+, NO+, O+ 3.1.1.4. Thermosphere It’s the layer of very rare air above the mesosphere (Table 02) 4|Page © 2024 Rahman, SMM  Figure 3.2: Basic features of the atmospheric layers (Source: Environmental Chemistry by S. E. Manahan, 7th Edition). 3.1.2. Hydrosphere: Greek “Hydro” means water. It is the accumulation of water in all its state (solid, liquid and gas) and the elements dissolved it in (sodium, magnesium, calcium, chloride etc). Figure 3.3: Water distribution throughout the earth’s surface (Source: USGS). 5|Page © 2024 Rahman, SMM So, all the waters that exist on this planet earth are known as the hydrosphere. No matter whether it’s in a gaseous (vapor), solid (snow), or liquid state (Fig. 3.3). 3.1.3. Lithosphere: Greek “Litho” means stone or rock. The Lithosphere is the outer, rigid shell of the solid earth. It is composed of the entire crust (oceanic and continental) and the top rigid position of the mantle lying above the partially melted layer (Fig. 3.4). In recent days, scientists are trying to specify the lithosphere within the crust (continental and oceanic) and upper mantle part of the earth’s interior. So, we can say that the lithosphere is the uppermost part of the earth’s interior that is directly involved with the ecological processes that are happening in our surrounding environment through the interaction between the air, water, and living organisms. Figure 3.4: Structure of the earth’s lithosphere (Source: Springer). Thickness varies from 50 km under the ocean bottom to about 100 km below continental surface. Composed predominantly of O2 and Si, with Al, Fe, Ca, Mg, K and other elements contributing fewer amounts. 3.1.4. Biosphere: The compartment where the living being can survive is called the biosphere. So, the fact is _ all the living organisms that exist on this planet earth are known as the biosphere, and it’s a zone consisting of atmosphere, lithosphere, and hydrosphere where life belongs. 6|Page © 2024 Rahman, SMM  Biosphere is the earth’s thin zone of air, water and soil It is capable of supporting life, ranging from about 10 km into the atmosphere to the deepest ocean floor The biosphere is made up of large areas called biom The biom is made up of many ecosystems Life of these zones depends on the suns energy, on the circulation of heat and essential nutrients 7|Page © 2024 Rahman, SMM