Lecture18 - EAS 1600 Introduction to Environmental Sciences...

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EAS 1600 Introduction to Environmental Sciences ____________________________ Class 18 - The Biosphere: Part 1 The Biosphere As An Organic Compound, Metabolic Processes ________________________________ We have now completed an initial investigation into the abiotic parts of the Earth System. Now let’s take look at the living part... What do we mean by the biosphere? “Although there may be problems in agreeing on a close definition of 'biosphere', that is not important. What is important is that there is widespread acceptance of the set of ideas conveyed by the term. The idea of living organisms as functional entities, processing energy and matter, reproducing, interacting with each other and with the physical environment ; and the idea that the entire biota, together with its physical environment, can be regarded as a single system. " (Ian Bradbury, The Biosphere, Belhaven Press, 1991) For different people, the word biosphere means different things ... 1. Biosphere = Gaia – Some scientists use the word “ biosphere” to denote what we have used the term “ Gaia ” to signify: The entire coupled system involving the atmosphere, ocean, lithosphere (and solid earth), as well as living systems . – This is the definition adopted by individuals interested in the new area of study referred to as Biospherics (see page on Biospherics) – On the other hand there is Lovelock’s statement that “... The name of the living planet ... (is) Gaia ... (it) ... is not a synonym of the biosphere. Biosphere ” can means different things ... 2. Biosphere = all living organisms In this definition the biosphere is: – “ ... defined as that part of the earth in which life exists.” (E. Hutchinson, in The Biosphere , W. H. Freeman and Co., San Francisco, pp 1 -12, 1970.) (But see excerpt from Hutchinson) 3. Biosphere = all organic C In this definition the biosphere is: defined as all living organisms and the remains of dead organisms that have not been re-mineralized to form inorganic compounds. This is the definition often adopted by scientists interested in biogeochemical cycles since the important chemical transformation in these cycles is the conversion of elements between their organic and inorganic forms. (Why do you suppose that is?) This is the working definition we will use .
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