Elements in life

Fig. 3.14. The total thermal entropy drive which underlies the energy connection between the cycling of elements in life and environment while energy is degraded.

The composition of living cells is related to the availability and usefulness of 15-20 elements (see Figure 4.3) and, as we shall see, changes in availability profoundly influenced evolution of chemotypes. However, it is probable that the collection of elements in life at any one time is a unique set. 

At the beginning of the chapter, I made a note of several other metals that are important for living organisms among them are zinc, magnesinm, manganese, copper, and cobalt. Here are a few words about the role of these elements in life. 

Life is made of three basic elements matter, energy and information... Any element in life that is not matter and energy can be reduced to information. 

The overall structure of River of Things comes from the Neruda poems. But a secondary structure comes from the tone—a playful attitude toward the narratives of each of the odes. Although the structure is loose, it is nevertheless present, and it shapes the rueful observation of Neruda with a tonal appreciation of those elements in life that we ignore but whose functionality Neruda and the filmmakers laud. 

In the discussion that follows reference will be made in a general but incomplete way to the function of the essential elements in life processes. In the case of some of these elements there is considerable doubt as to their exact roles in plant growth, and also some differences in opinion among investigators. Further information on this is available in textbooks dealing with plant physiology and soil fertility (see Russell, 1961, Tisdale and Nelson, 1966) as well as in many journal articles such as those of McMurtrey Jr. and Robinson (1938), Hewitt (1951), McElroy and Nason (1954), Starkey (1955), Gauch... 

Energy costs are often the biggest element in life cycle costs, especially for equipment that runs most of the time. The energy cost used in this study is set to 70 EUR/MWh. 

The chemical speciation study of trace elements in life sciences has been paid more and more attention in recent years, mainly because it can provide more significant information on the pathway, distribution, accumulation, excretion, and functions of trace elements in biological systems of interest than the traditional bulk composition study. Almost all speciation techniques consist of two steps. The first step involves the separation of species from the sample followed by the second step of element specific detection. The so-called molecular neutron activation analysis (MoNAA) or speciation neutron activation analysis (SNAA) is, in fact, a combination of conventional NAA with physical, chemical, or biological separation procedures in order to meet the ever-increasing need for chemical species study. 

Carbon is unique among the elements in the vast number and variety of compounds it can form. With hydrogen, oxygen, nitrogen, and other elements, it forms a very large number of compounds, carbon atom often being linked to carbon atom. There are close to ten million known carbon compounds, many thousands of which are vital to organic and life processes. 

The acceptance of the name was premature because both Russian and American efforts now completely rule out the possibility of any isotope of Element 102 having a half-life of 10 min in the vicinity of 8.5 MeV. Early work in 1957 on the search for this element, in Russia at the Kurchatov Institute, was marred by the assignment of 8.9 +/- 0.4 MeV alpha radiation with a half-life of 2 to 40 sec, which was too indefinite to support discovery claims. 

Oxygen is the most abundant element on earth The earths crust is rich in carbonate and sili cate rocks the oceans are almost entirely water and oxygen constitutes almost one fifth of the air we breathe Carbon ranks only fourteenth among the elements in natural abundance but trails only hydro gen and oxygen in its abundance in the human body It IS the chemical properties of carbon that make it uniquely suitable as the raw material forthe building blocks of life Let s find out more about those chemi cal properties... 

Equations 13.31 and 13.32 are only valid if the radioactive element in the tracer has a half-life that is considerably longer than the time needed to conduct the analysis. If this is not the case, then the decrease in activity is due both to the effect of dilution and the natural decrease in the isotope s activity. Some common radioactive isotopes for use in isotope dilution are listed in Table 13.1. 

By contrast, uranium fuels for lightwater reactors fall between these extremes. A typical pressurized water reactor (PWR) fuel element begins life at an enrichment of about 3.2% and is discharged at a bum-up of about 30 x 10 MW-d/t, at which time it contains about 0.8 wt % and about 1.0 wt % total plutonium. Boiling water reactor (BWR) fuel is lower in both initial enrichment and bum-up. The uranium in LWR fuel is present as oxide pellets, clad in zirconium alloy tubes about 4.6 m long. The tubes are assembled in arrays that are held in place by spacers and end-fittings. 

Oxygen is by far the most abundant element in cmstal rocks, composing 46.6% of the Hthosphere (4). In rock mineral stmctures, the predominant anion is, and water (H2O) itself is almost 90% oxygen by weight. The nonmetaUic elements fluorine, sulfur, carbon, nitrogen, chlorine, and phosphoms are present in lesser amounts in the Hthosphere. These elements aU play essential roles in life processes of plants and animals, and except for phosphoms and fluorine, they commonly occur in earth surface environments in gaseous form or as dissolved anions. 

Chlorine. Nearly all chlorine compounds are readily soluble in water. As a result, the major reservoir for this element in Figure 1 is the ocean (5). Chloride, as noted earHer, is naturally present at low levels in rain and snow, especially over and near the oceans. Widespread increases in chloride concentration in mnoff in much of the United States can be attributed to the extensive use of sodium chloride and calcium chloride for deicing of streets and highways. Ref. 19 points out the importance of the increased use of deicing salt as a cause of increased chloride concentrations in streams of the northeastern United States and the role of this factor in the chloride trends in Lake Ontario. Increases in chloride concentration also can occur as a result of disposal of sewage, oil field brines, and various kinds of industrial waste. Thus, chloride concentration trends also can be considered as an index of the alternation of streamwater chemistry by human development in the industrialized sections of the world. Although chlorine is an essential element for animal nutrition, it is of less importance for other life forms. 

Zinc, like most metals, is found in all natural waters and soils as well as the atmosphere and is an important trace element in plant and animal life (see Mineral nutrients). Rocks of various kinds contain 20—200 ppm zinc and normal soils 10—30 ppm (average ca 50 ppm) in uncontaminated areas. The average zinc content of coal is 33 ppm. Seawater contains 1—27 )-lg/L (median ca 8 p.g/L), and uncontaminated freshwater usually <10 / g/L. 

The key element of life-cycle design is Life-Cycle Assessment (LCA). LCA is generally envisioned as a process to evaluate the environmental burdens associated with the cradle-to-grave life cycle of a produc t, process, or ac tivity. A produc t s life cycle can be roughly described in terms of the following stages ... 

Calcium, as noted above, is the fifth most abundant element in the earth s crust and hence the third most abundant metal after A1 and Fe. Vast sedimentary deposits of CaC03, which represent the fossilized remains of earlier marine life, occur over large parts of the earth s surface. The deposits are of two main... 

W. KaIM and B. SchwederSKI, Bioinorganic Chemistry Inorganic Elements in the Chemistry of Life, Wiley, Chichester, 1994, 401 pp. 

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