Biological fractionation

Galimov EM (1985) The biological fractionation of isotopes. Academic Press, Orlando... 

The understanding of isotope effects on chemical equilibria, condensed phase equilibria, isotope separation, rates of reaction, and geochemical and meteorological phenomena, share a common foundation, which is the statistical thermodynamic treatment of isotopic differences on the properties of equilibrating species. For that reason the theory of isotope effects on equilibrium constants will be explored in considerable detail in this chapter. The results will carry over to later chapters which treat kinetic isotope effects, condensed phase phenomena, isotope separation, geochemical and biological fractionation, etc. 

Galimov, E.M. The Biological Fractionation of Isotopes, Academic, New York, 1985. 

Anbar AD, Roe JE, Holman ES, Barling J, Nealson KH (2000) Non-biological fractionation of iron isotopes. Science 288 126-128... 

Nevertheless, in laboratory batch tests on the (multi-)sequential chemical/biological treatment suspended biomass is normally used to determine the biological fraction of DOC since the amount of biomass added to each batch is easier to control and measure (and indeed no washout is possible) (Karrer et al., 1997 Jochimsen, 1997). In most cases the operation of a continuous-flow sequential ozonation/biodegradation unit cannot be recommended without having performed batch tests before. 

Fig. 7-13. Relative effect of isotopic mass on reaction kinetics, expressed as ]/m2/mt (where m2 and m, are the masses of the nuclides plotted and the most common stable nuclide of the same element, respectively). Biological fractionation is only likely to be important for elements with atomic masses less than — 20, especially in the case of deuterium and tritium.

Here, the preformed pool includes contributions from the saturation concentration and the degree of disequilibrium at the point of subduction. The biological fraction has contributions from both soft-tissue and carbonate pumps (Volk and Hoffert, 1985). Following Brewer (Brewer, 1978) we may, as a first approximation, interpret the soft-tissue contribution to be related to the biological fraction of nitrogen by a fixed, Redfieldian stoichiometry ... 

Woodruff F., Savin S. M., and Douglas R. G. (1980) Biological fractionation of oxygen and carbon isotopes by recent benthic foraminifera. Mar. Micropaleo. 5, 3-11. 

Isotopic fractionation between ferric and ferrous species over a wide range of oxidation rates is +1.3 per mil to +1.5 per mil (Croal et al., 2003). Isotopic fractionation between ferric and ferrous species over wide range of reduction rates is +1.3 per mil (Beard et al., 1999, 2003). Biological fractionation nearly half that in inorganic ferric-ferrous system (Johnson et al., 2002). 

Ambient Isotopic Studies of Mercury—Biological Fractionation of Mercury Isotopes... 

Lecuyer C, Grandjean P, Sheppard SMF (1999) Oxygen isotope exchange between dissolved phosphate and water at temperatures <135°C Inorganic versus biological fractionations. Geochim Cosmochim Acta 63 855-862... 

Different tissnes from a single animal retain biological fractionations Bone CO3 altered for archeological and Pleistocene bulk samples, and for some pretreated Pliocene samples Pleistocene bone PO4 and dentin PO4 and CO3 may be altered no evidence for enamel CO3 or PO4 alteration 1,2, 11, 14, 23, 25, 26, 28, 29, 30, 37, 39, 40, 43, 45... 

Do different tissues from the same individual retain biological fractionations Different tissues have known isotopic offsets in modem samples. Intercomparison of different tissues (e.g., of collagen vs. bone CO3) indicates that bone and possibly dentin CO3 is already altered for Pleistocene samples (Land et al. 1980, Lee-Thorpe and van der Merwe 1991), although some Plio-Pleistocene bone CO3... 

Further biological fractionation takes place in animals and the measurement of the animals isotopic ratios can be used to study animal ecology (Rundel et al. 1988). Finally, the isotopic composition of humans may reflect the composition of their diets and the principle we are what we eat can be used in archeological research to reconstruct the diet of prehistoric humans (Chen and Orna 1996) and hominids that predate the genus Homo (Sponheimer and Lee-Thorp 1999). 

Ewing, S.A., Yang, W., DePaolo, D.J., Michalski, G., Kendall, C., Stewart, B.W., Thiemens, M and Amundson, R. (2008) Non-biological fractionation of stable Ca isotopes in soils of the Atacama Desert, Chile. Geochim. Cosmochim. Acta, 71, 1096-1110. 

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