The Biosphere

Abstract

Studying the living organisms , both plants and animals, their past and present mode of life and interactions, the way they function, can be a very complex task that broadly encompasses the sciences of biology, zoology, and ecology. This task is made very difficult by the constant and fast-paced changes and interactions between the organisms we study and their environment. The organisms also exist within a very complex framework, or web, of relationships involving energy, food, and the natural environment. At any point in this web, isotopes will fractionate and the extent of the fractionations will inform us about the processes that occurred and the conditions at which they occurred.

Further Reading

Fortunately, there are some excellent books and journal articles on the topic of isotopes in living beings. Here is a brief selection of these:

• Stable Isotope Ecology, B. Fry, Springer, 2008, ISBN 978-0-387-30513-4.

• Stable Isotopes in Ecology and Environmental Science, R. Michener and K. Lajtha, Editors, Blackwell, 2007, ISBN 978-1-4051-2680-9. This book is an absolute gem: highly recommended.

• Stable isotopes in Ecological Research, P.W. Rundel, J.R. Ehleringer, and K.A. Nagy, Editors, Springer, 1988, ISBN 978-1-4612-8127-6.

• Stable Isotopes as Indicators of Ecological Change, T.E. Dawson, and R. Siegwolf, Editors, Academic Press, 2011, ISBN 978-0-080-55100-5.

• Handbook of Environmental Isotope Geochemistry, M Baskaran, Springer Science, 2011, ISBN 978-3-642-10637-8.

• Tracking Animal Migration with Stable Isotopes, K.A. Hobson and L.I. Wassenaar, Academic Press, 2018, ISBN 978-0-128-14724-5.

• Stable Isotopes and Biosphere - Atmosphere Interactions: Processes and Biological Controls, L.B. Flanagan, J.R. Ehleringer, and D.E. Pataki, Editors, Elsevier, 2004, ISBN 978-008-052528-0.

• O’Connell. T.C., Hedges, R.E.M., Healey, M.A., and Simpson, A.H.R.W. (2001) Isotopic composition of hair, nail and bone: modern analyses. Journal of Archeological Science, 28, 1247–1255.

• Bol, R., and Pflieger, C. (2002) Stable isotope analyses (¹³C, ¹⁵N, and ³⁴S) analysis of the hair of modern humans and their domestic animals. Rapid Communications in Mass Spectrometry, 16, 2195–2200.

• Still, C.J., and Powell, R.L. (2010) Continental-scale distributions of vegetation stable carbon isotope ratios. In B. West et al. (eds.), Isoscapes: Understanding Movement, Pattern, and Process on Earth Through Isotope Mapping. Springer Science + Business Media B.V. 2010, pp. 179–193.

Questions

• What type of fractionation is most common in the biosphere?

• What are the two main mechanisms of carbon fixation and how do they affect carbon isotopes fractionation? When did the second type appear and how do we know that?

• How can we derive the diet or food sources of an animal (or a human)? The isotopes of which elements would we use?

• What is trophic shift? How does it work and on what basic principle is it based?

• How can we study the diet of an extinct animal? What factors must we take into account?