Mar 04, 2024
Mar 04, 2024
The earth was formed about 4,5 billion years ago ( with an uncertainty of 1%and was largely completed within 10-20 million years. The earliest undisputed evidence of life dates at least 3.5 billion years ago. With the origin of life on this planet the earth got transformed from geoshere (inanimate matter) to biosphere.
Dictionary meaning of biosphere is “the regions of the surface and atmosphere of the earth or another planet occupied by living organisms”
The earth may be considered as a biosphere. It is the global sum of all ecosystems. It is an autonomous system which is sustained by solar energy. Various living animals and plants compose its living (biotic) component while the physical constituents such as soil, climate, space etc. constitute its abiotic component. It is an integrated whole. A nonstop continuous movement of energy and matter goes on between various components of the system.. A study of carbon, nitrogen, oxygen and water content of the biosphere and of biological processes reveals that chains of cycles of each substance are involved..In which matter and energy are transferred from one organism to another and from living organism to abiotic components of the system and vice versa. Nothing is wasted and almost nothing is transformed in such state as to get lost to the system. Almost nothing, because a very insignificant amount gets deposited as geological leftover in the form of coal and oil and so gets out of the cycle.
It is now an accepted fact that the living and non living components of the biosphere are intimately interrelated. We know that presence of oxygen and carbon dioxide is prerequisite for the existence of life on this planet. But simultaneously we need to be aware that their presence in the atmosphere is a consequence of the activities of living organisms. Our present understanding is that the initial composition of the atmosphere of the earth was radically different. Most probably it contained methane and ammonia among few other gases. Structure and composition of the living matter synthesized in such an environment was different from the present one. The process of organic evolution triggered a simultaneous process of change in the chemical composition of the environment. The present composition of the atmosphere was perhaps reached at the time since when fossil records in this planet begin. Most probably this time span extends between the time of the origin of life and the present time. It has been calculated that total carbon dioxide and oxygen of the atmosphere complete one cycle through the living system every 300 and 2,000 years respectively.
Just like the composition of the atmosphere the structure of the water of seas and oceans is also a consequence of life processes and a prerequisite too. Formerly it was understood that salt content of sea water is is continuously increasing due to soil erosion.. Therefore the age of the sea can be calculated by measuring its concentration. By this method we may be able to determine the time taken for salt to accumulate up to the present level in the sea. But by this method of calculation the age of the seas comes up to merely a very few millions of years even though other indicators point it to be many billion years.
So it appears that the composition of sea water prior to the birth of life remained constant in spite of accumulation of soil in it. Change in the composition of sea water occurred only after life was born in sea water. Ionic contents of all the types of protoplasm and sea water bear close resemblance. Te cells of terrestrial and fresh water organisms may be considered to be sacs of sa water which have invented a mechanism to maintain the evidences of their primitive sea water habitat.
Clinching knowledge of all the chemical cycles of the sea has not been obtained up till; now; even though we may understand calcium cycle quite easily. Through this cycle calcium is regularly deposited in the form of limestone through corals, seashells oysters and other molluscs and then they are dissolved in sea water through the ages. Sodium is dissociated relatively slowly, perhaps through the inorganic processes, which have resulted in. huge deposits of salt in various regions of the earth. Thus each chemical of the sea has its own independent cycle.
Vegetation growing at a place is determined by a number of factors. Soil is one among them. It is also true that the character of soil is determined by the vegetation growing there Different types of soil are formed by different types of soil forming rocks, climate of the place and interaction between living organisms, earthworms and plants.
Thus biosphere, or the living area of the earth’s surface, is a dynamic system in which living and nonliving processes are closely interwoven. To the best our knowledge these processes have remained constant during the whole period of geological fossil records. Presence of several producer, consumer and decomposer chains of present times can be detected in the earliest fossil records, although this identification can be done conclusively only in the marine environment. Extension of this system to fresh water and terrestrial environs can also be observed and can be detected in the complex systems and subsystems of flowering plants and insects.
Biomass, the total mass of all the living organisms on the planet, has been constant over a considerable length of time, (most probably from the beginning of Cenozoic era or since Mesozoic era) Though a number of species have become extinct and quite new species have appeared during this time span. G. G. Simpson has named it “relay effect”. In this process a species has been handing over its role to another species. Existing species go on getting extinct while new species continue appearing, but the nature of the processes does not change. The system remains intact.
With the advent of man as a maker of tools and as a producer of food, new relationships were introduced into the system. The biosphere started to transform into the noosphere, which started to become dominated by the phenomenon of the human mind. In another way, we could say that the biosphere started changing from a system-in-itself into a "resource" for one of its component species, Homo sapiens. This raises many problems for the biosphere and for Homo sapiens.
The noosphere is the third in a succession of phases of development of the earth after the geosphere (inanimate matter) and the biosphere (biological life). Just as the emergence of life fundamentally transformed the geosphere, the emergence of human cognition fundamentally transformed the biosphere and threatened its survival. Thanks to his mastery of developed technology he is interfering effectively in the functioning and maintenance of various ecosyestems and thereby threatening the dynamic and delicate structure. It has become imperative for our own survival that we develop our knowledge and respect for nature , Man is a component of nature and not its master.
More by : Ganganand Jha