THE BIOSPHERE, LITHOSPHERE, HYDROSPHERE AND ATMOSPHERE The area near the surface of the earth can be divided up into four inter- connected geo-spheres that make up the carbon cycle these include:
Lithosphere Hydrosphere Biosphere Atmosphere
The understanding of '-sphere- in this situation means 'to surround or encompass' . The following help us understand the mean of the four spheres:
Lithosphere - litho referring to rocks and minerals Hydrosphere - hydro referring to water Biosphere - bio referring to life Atmosphere - atmo referring to steam and vapour
THE LITHOSPHERE -
It is believed the lithosphere evolved about 4.6 billion years ago. The lithosphere refers to the solid, rocky crust that covers the entire planet. This solid, rocky crust is composed of a number of different rocks that have been grouped into three categories based on how they are formed. These three groups include:
Metamorphic rocks – Metamorphic rocks are formed by heat and / or pressure from pre-existing rocks. Igneous rocks – igneous rocks are formed by the cooling of hot molten rock also known as magma. When the hot magma cools it begins to harden meaning once it had fully cooled it create what is known to be an igneous rock. Sedimentary rocks – sedimentary rocks are formed from pre- existing rocks. When rocks erode and mix with other dirt, clay and particles then settle together the mix together to form a sedimentary rock.
The lithosphere includes a various number of different landforms such as mountains, valleys, rocks, minerals and soil. The lithosphere is constantly changing due to forces and pressures such as the sun, wind, ice, water and chemical changes. The earth’s surface is composed into two types of lithospheres. There are known as the oceanic and continental lithospheres. The oceanic lithosphere includes the uppermost layers of mantle which is topped with a thin yet heavy oceanic crust. This is where the hydrosphere and lithosphere meet. The continental lithosphere includes the uppermost layers of mantle which is topped with a thick yet light continental crust. This is where the atmosphere, biosphere and hydrosphere meet the lithosphere.
THE HYDROSPHERE -
The hydrosphere refers to the most important resource. The hydrosphere includes all forms of water in the Earth’s environment. The forms of water include things such as the ocean, lakes, rivers, snow and glaciers, water underneath the earth’s surface and even the water vapour that is found in the atmosphere. The hydrosphere is always in motion as seen through the movement and flow of water in rivers, streams and the ocean (beach). Plant and animal organisms rely on the hydrosphere for their survival as water is essential. The hydrosphere is also home to many plants and animals and it believed that the hydrosphere covers approximately 70% of the earth’s surface
THE BIOSPHERE -
The biosphere is composed of all living organisms, including; plants and animals. It is believed that all life exists in the biosphere. Most of the living organisms are found from up to three meters below ground to thirty meters above it and also in the 200 meters of the ocean and seas. The biosphere could not survive if it wasn't for the other spheres as all organisms need water from the hydrosphere, minerals for the lithosphere and gases from the atmosphere. Energy flow is essential to maintain the structure of organisms by the splitting of phosphate bonds.
THE ATMOSPHERE - The atmosphere refers to the air that surrounds the earth. The atmosphere is always in motion and constantly changing. It’s believed that there are about 14 different gases that make up the atmosphere. The atmosphere is also responsible for the weather as the weather occurs within the lower atmosphere. The bottom layer of the atmosphere is known as the troposphere. The troposphere is where the weather happens. It is the warmest near the Earth because of the heat rising from the earth’s surface but it becomes colder with altitude. This layer is separated from the next by what is known as tropopause. The tropopause is the point in which temperatures will begin to change due to the increase of altitude. Above the tropopause is the stratosphere. The stratosphere is where there large concentration of ozone gas is found. The ozone gasses are essential as they absorb a large percent of radiant solar energy, protecting the earth from harmful ultra violet rays also known as UV. The coldest of spheres is known as the mesosphere this is where the water vapor often freezes to create clouds that are purely made of ice. The mesosphere is separated from the thermosphere by the mesopause. The topmost layer is known as the thermosphere, this is where many satellites circle the earth. Due to the thin air and proximity of the sun, the temperatures in the thermosphere tend to rapidly increase and decrease.
Important Points: ● The elastic, invisible and tasteless mixture of gases that surrounds the earth form what is termed as air. ● The atmosphere denotes all the air surrounding the earth. ● The environment is the general term with major constituents as biotic and abiotic environments and it also includes atmosphere having major constituents of N2, O2, and other gases. ● Weather is the general condition of atmosphere at a particulat time and the place. ● Weather can be described by various meterological phenomenon such as rain fall, atmospheric pressure, cloudiness, wind speed and direction, temperature, humidity etc. ● The average weather conditions of a place or a region throughout the season is called climate, which is governed by latitude position in relation to oceans or continents, local geographical conditions etc. ● Climate can be described by a number of terms like rate of evaporation, wind speed and direction, temperature, lightening and thunder storms, solar radiation, incidences of fog, visibility etc. ●The science which deals with climate and climate phenomenon is known as climatology. Air as an ecological factor: The gaseous mixture of troposphere is nothing but air. The air is utilized by organisms in the process of respiration to liberate chemical energy from food during oxidation. The presence of nitrogen, oxygen and carbon dioxide in air is of great importance because these gases keep on cycling in nature between organisms and their atmosphere through various cycles such as carbon cycle, nitrogen cycle, water cycle etc. Oxygen is available in sufficient amounts in land environment. It becomes scarce only at high altitude, deep in ground or in water soaked soil. Oxygen dissolved in water is used up by aquatic organisms. The amount of oxygen dissolved in water depends upon the temperature and depth of water. Warm water has a lower capacity to dissolve oxygen than the cold water. Carbon dioxide provides carbon to the plants. Atmospheric nitrogen is directly used by some nitrogen fixing bacteria of roots of some plants. Reaction of atmospheric oxygen: Oxygen in the troposphere plays an important role in the processes taking place on earth’s surface. Oxygen takes part in energy producing reaction like burning of fossil oils. CH4 (in natural gas) + 2O2 = CO2+ 2H20 Atmospheric oxygen is also used by aerobic organisms in the degradation of organic material or in oxidative weathering processes. HCHO + O2 =(Organisms) CO2+ H20 The CO2 and H2O formed in the above reactions are utilized by the green plants in the process of photosynthesis and oxygen is again returned in the atmosphere. Atmospheric Carbon dioxide – Carbon dioxide is the non pollutant species in the atmosphere. The atmospheric CO2, along with water vapours, is mainly responsible for the absorption of solar energy from the sun (photosynthesis) and re-radiation of this energy back to the earth’s surface. An increase in concentration of CO2 in atmosphere is found to increase the temperature of the earth. For example, CO2 in the atmosphere prevents the long wave infra red heat radiation from the earth from escaping into outer space and deflect it back to the earth causing rise in temperature of the earth. This is called as green house effect. Climate and Weather Climate is generally defined as the average state of weather and is one of the basic elements in the natural environment. Weather is day to day condition of the atmosphere at any place as regards temperature, rainfall, wind, humidity, sunshine and cloudiness etc. Climate affects land forms, soil types and vegetation. Weather refers mainly to a day, a week, a month or a little longer (i.e. short periods), while climate is concerned with average conditions over long periods. Both weather and climate are affected by various factors, such as: 1. Direction of the sun’s rays. 2. Length of the day. 3. Altitude 4. Distribution of land and water bodies. 5. Direction of mountain range. 6. Air pressure 7. Wind and ocean currents etc. Inversion of Temperature: Altitude affects the climate in several ways. As we go higher up a mountain there is a decrease in temperature. The rate of decrease in temperature is not uniform and varies with time of day, season and place. It has been observed that the average decrease of temperature upward in the troposphere is about 6-6.5◦C per km above sea level. This rate of fall of temperature with height is called as normal lapse rate. Hydrosphere Hydrosphere covers more than 75 percent of the earth’s surface as oceans or as fresh water. Hydrosphere includes sea, rivers, oceans, lakes, ponds, streams etc. Evaporation of water from oceans, cloud formation and precipitation are responsible for worldwide water supply through hydrological cycles. Water is essential to all life. Life was first originated in water. Solubility of gases in water Most gases especially those that are essential for life are soluble in water. Oxygen dissolved in water is used by most living organisms for respiration. Oxygen is a limiting factor for aquatic animals as the saturation concentration of oxygen in water is governed by temperature and salinity. The lower the temperature, the greater the oxygen retaining capacity of water, whether it is fresh water or sea water. Respiration, decomposition of organic materials and stream pollution all tend to reduce the amount of available oxygen. The deepest layers of water usually have low oxygen concentration in deeper lakes and ocean areas. This is due to continuous decomposition of organic materials, respiration of organisms and complete absence of photosynthetic activity. Nitrogen is significantly less soluble in water then oxygen. It is chemically inert and does not react with water. Some bacteria, fungi, blue green algae etc, can use nitrogen to satisfy their nitrogen requirement Carbon dioxide is produced by the decomposition of organic matter and the respiratory activity of aquatic plants and animals. CO2 gas is most essential for the photosynthesis of green plants. CO2 also combines with water to form carbonic acid (H2CO3) which influences the PH or H+ ion concentration of water. Lithosphere Lithosphere means the mantle of rocks constituting the earth’s crust. The solid component of the earth is called lithosphere, which is related with edaphic factor and includes mainly soil, earth, rocks and mountains etc. The lithosphere mainly contains three layers- crust, mantle and outer and inner core. The core is the central fluid or vapourised sphere having diameter of about 2500 km. form the centre. Core is probably composed of nickel-iron. The mantle extends about 2900-3000 km above the core and is in the molten state. The outer most solid zone of the earth is known as crust. It is about 8-40 km above the mantle. The surface of crust is covered with the soil. So the soil is probable the most significant part of the lithosphere. Soil- Soil is the upper most part of the earth’s crust, and is a mixture of organic as well as weathered rock and materials necessary for the growth of plants. The organic matter and weathered rock materials are formed through the physical, chemical and biological processes occurring slowly and slowly for a long period at earth’s surface. Soil is a store house of minerals, a reservoir of water, a conserver of soil fertility, a producer of vegetative crops, a home of wild life and livestock. The soil also supplies nutrients to the plants and is one of the most important ecological factor, called edaphic factor. The science which deals with the study of soil is called soil science, pedology or edaphology. Besides being the source of nutrients and water to plants, the soil is also the medium for the detritus food chain. A number of soil microbes such as bacteria, algae, fungi, protozoa etc. bound in or on soil particles decompose the nutrients released in detritus and taken back into the plants through their roots. Rocks- Soil is formed by different kinds of rocks. Rocks are made of different kinds of minerals. Some important minerals are- Asbestos- It is a heat resistant mineral and is used to make fireproof materials. Calcite- This mineral makes up the chalk and limestone. Diamond- It is a form of carbon and is the hardest substance known. Fluorite- It is mainly used in the steel industry. Graphite- Like diamond, it is another form of carbon and is used in making lead pencils. Gypsum- Gypsum is used in the manufacture of chalk and plaster of Paris. Haematite- It is deep blood red coloured ore of iron. Quartz- It is the mineral that makes up sand and gravel. It is used in making electrical instruments. Talc- It is also known as soapstone and is the softest mineral. Talcum powder is made from talc. It should be noted that- Important 1. Geologists have classified nearly 3000 minerals. 2. Of the 92 elements (basic chemical substances) that occur naturally in the Earth’s crust, 22, including gold and silver, are sometimes found in free states. The other occur in combinations with one or more other elements. 3. Sedimentary rocks cover about 75% of the world’s land areas. 4. Igneous rocks make up 95% of the top 16 km (10 miles) of the earth’s crust. 5. The moon rocks collected by astronauts are igneous in type. There are no sedimentary rocks on the moon, because moon has no atmosphere and so weathering and erosion do not occur. ● The earth is a cold, spherical, solid planet of the solar system, which spins on its axis and revolves round the sun at a certain constant distance. ● The solid component of the earth is known as lithosphere. ● The core is the central fluid or vapourised sphere having diameter of about 2500 km from the centre and it is generally made of nickel- iron. ● The mantle extends about 2900 km above the core. This is in molten state. ● The crust is the outermost solid zone of the earth. It is about 8 to 40 km above the mantle. ● The crust is very complex and its surface is covered with the solid supporting rich and varied biotic communities. ● The soil is one of the most important ecological factor, called edaphic factor. ● Soil is the most characteristic feature of terrestrial environment. ● Soil is loose, unconsolidated top layer of earth’s crust. ● Soil in the form of mud is the main source of nutrients for all aquatic plants (hydrophytes), rooted or submerged or free floating. Biosphere Biosphere indicates domain of living organisms and their interactions with environment, i.e. the atmosphere, hydrosphere and lithosphere. ● The entire world basically can broadly be classified into biotic world and abiotic world. The abiotic world can further be divided into three classes: The atmosphere (air), the hydrosphere (water) and the lithosphere (earth). To these three ecological components, we can add the biosphere, known as biotic world or biological world. ● The atmosphere, the hydrosphere, the lithosphere and the biosphere represent four major global components of the world ecosystem. ● The biosphere is that part of the earth in which life exists. In other words, the sum of those portions of the atmosphere, hydrosphere and lithosphere into which life penetrates is nothing but biosphere. ● Biosphere or ecosphere may be regarded as a biochemical system capable of capturing, converting, storing and utilizing the sun’s energy. ● The biosphere can be divided into a series of biogeographical regions, each inhabited by distinctive species of animals and plants. These organisms move freely from one place to another within each region, but not from one region to another, thing being prevented by various barriers like river, lake, sea, desert, mountain etc.