Living Organic Matter

Wickman (1952) and Craig (1953) were the first to demonstrate that marine plants are about 10%o emiched in C relative to terrestrial plants. Since that time numerous studies have broadened this view and provided a much more detailed account of isotope variations in the biosphere. The reason for the large C-isotope differences 

One of the most important groups of all living matter is marine phytoplankton. Natural oceanic phytoplankton populations vary in 8 C-value by about 15%c (Sackett et al. 1973 Wong and Sackett 1978). Rau et al. (1982) demonstrated that different latitudinal trends in the carbon isotope composition of plankton exist between the northern and the southern oceans south of the equator the correlation between latitude and plankton C-content is significant, whereas a much weaker relationship exists in the northern oceans. 

Organic material that comprises living matter consists of carbohydrates (saccharides, Sacc ) - the first product of carbon fixation - and proteins ( Prot ), nucleic acids ( NA ) and lipids ( Lip ) with prevailing regularities within these compound 

What is known for a long-time lipids are depleted in by 5-8%o relative to the bulk biomass. Recently, Teece and Fogel (2007) demonstrated that the carbohydrate fraction of various organisms on average is enriched in by 4.6%c relative to the bulk. Even larger variations are observed for individual amino acids (Abelson 

The component typically analyzed in plants is cellulose, which is the major structural carbohydrate in plants (Epstein et al. 1976, 1977). Cellulose contains 70% carbon-bound hydrogen, which is isotopically non-exchangeable and 30% of exchangeable hydrogen in the form of hydroxyl groups (Epstein et al. 1976 Yapp and Epstein 1982). The hydroxyl-hydrogen readily exchanges with the enviromnen-tal water and its D/H ratio is not a useful indicator of the D/H ratio of the water used by the plants. 

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Consequences of Ozone Depletion. Ozone depletion over Antarctica is causing renewed concern about the consequences of increased levels of UV reaching the earth s biosphere. One area of concern involves the free-floating microscopic plants, known collectively as phytoplankton (the grass of the sea), which through the process of photosynthesis, fix carbon dioxide into living organic matter. Phytoplankton forms the basis of the marine food chain on which zooplankton (animal plankton) and all other components of the ecosystem depend for their sustenance. 

Fluxes are linear functions of reservoir contents. Reservoir size and the residence time of the carbon in the reservoir are the parameters used in the functions. Between the ocean and the atmosphere and within the ocean, fluxes rates are calculated theoretically using size of the reservoir, surface area of contact between reservoirs, concentration of CO2, partial pressures of CO2, temperature, and solubility as factors. The flux of carbon into the vegetation reservoir is a function of the size of the carbon pool and a fertilization effect of increased CO2 concentration in the atmosphere. Flux from vegetation into the atmosphere is a function of respiration rates estimated by Whittaker and Likens (79) and the decomposition of short-lived organic matter which was assumed to be half of the gross assimilation or equal to the amount transferred to dead organic matter. Carbon in organic matter that decomposes slowly is transferred... 

Carbon in living organic matter in the ocean surface layer. 

Sunda, W. G. 1995. The influence of nonliving organic matter on the availability and cycling of plant nutrients in seawater. In Role of Non-Living Organic Matter in the Earth s Carbon Cycle (R. G. Zepp and C. H. Sonntag, Eds.), pp. 191-207. Wiley, New York. 

Oxidations and reductions. The synthesis of the overall biosphere is largely a reduction of COj, water, sulfate and nitrate (or N2) to provide the major element components (C, H, O, N, S) of living organic matter. Oxidized forms of these elements are regenerated by subsequent respiratory, fermentative and other degradative processes. 

In addition to respiration, a death process is introduced for living organic fractions (especially for algae and consumers). This process transforms living organic matter into biodegradable and inert organic particles. 

In all experiments, assimilation was determined more by the type of diet, that is the species composition of microflora and the proportion of living and non-living organic matter, than by the technique used. Thus, while criticisms of some of the techniques used to measure assimilation. . . may have a physiological basis, it appears that differences in digestion of various food sources are so great that they cannot be attributed to the method used. 

The absolute Gd concentration can be evaluated by comparing the emission of prompt y-rays from the nuclide with those from hydrogen, which is constantly present in live organic matter (Figure 11.27) [13]. To avoid overestimation of Gd, it is important to prevent dehydration of specimens before evaluation. 

Petroleum, or crude oil, is believed to be the product of microbial degradation of living organic matter that existed several hundred million years ago. Crude oil, a dark viscous Uquid, is primarily a mixture of several hundred different hydrocarbons, particularly straight-chain alkanes, some branched alkanes, and varying quantities of aromatic hydrocarbons. Distillation yields several fractions with a typical product distribution, as shown in Table 3-3. The composition of petroleum varies widely, depending on the origin of the oil. 

There are a number of mechanisms associated with this form of corrosion, and detailed explanations are available in the literature. Most MIC takes the form of pits that form underneath colonies of living organic matter and mineral and biodeposits. This biofilm creates a protective environment where conditions can become quite corrosive and corrosion is accelerated. 

In summary, the omnipresence of chirality in the structure of the living organic matter and its importance for the natural life processes are today out of any question. Chirality is involved in the metabohc processes, most of which appear to be stereoselective. The understanding of a vital role played in our world by chirality is relatively new, and the subject still needs further extensive studies. One important precondition of success with such studies is an easy availability of convenient and well-performing analytical tools that are powerful enough to separate the enantiomer mixtures and to isolate individual antimers for further investigations. 

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