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26107 results in Geochemistry and environmental chemistry

Page 1305 of 1306

  • Acid–base regulation in fishes: 2. Biological responses and limitations

  • Edited by R. Morris, E. W. Taylor, D. J. A. Brown, J. A. Brown
  • Book:
    Acid Toxicity and Aquatic Animals
    Published online:
    05 February 2012
    Print publication:
    16 March 1989, pp 99-112

  • Summary

    Introduction

    The previous chapter (Heisler, this volume) describes the physiological mechanisms responsible for acid–base regulation in fishes. This chapter follows directly from Heisler's account and describes the physiological effects of and responses to exogenous variables (temperature, oxygen and carbon dioxide levels and pH) and endogenous variables (exercise, feeding and anaemia) which affect acid–base regulation and may limit the survival of fish.

    Exogenous perturbations

    Temperature

    (i) Physico-chemical basis Temperature affects the acid–base status of fish because it affects the chemical equilibria both of water and of the principal buffer systems of the blood and intracellular fluids. A small part of pure water is normally dissociated into H+ and OH-; at 24 °C the quantity of each is 10-7M, and the pH is 7. At 0 °C, however, dissociation is reduced so that the pH of pure water is 7.47, and at 37 °C it is 6.81. Temperature also influences the important physiological buffers to an extent dependent upon the value of ΔH° (the latent heat of ionization) for each dissociation reaction. This value for water is about 7000 cal mol-1, but varies from only about 2200 for the bicarbonate system (which has a very flat temperature response) to more than 8000 for certain protein groups (Cameron, 1984; Reeves, 1976; Reeves & Malan, 1976). An important aspect of these temperature-induced changes in acid–base status is that they determine the net charge of proteins; the net charge in turn affects many biochemical properties, especially of enzymes (Somero, 1981).

Geological Magazine
    • Journal
      • You have access: full
      • Open access
  • Geological Magazine is one of the oldest and best-known journals in the earth sciences. Its global circulation, broad scope and commitment to high quality keep the journal at the forefront of the field. It publishes original papers, review articles, rapid communications and discussions about all aspects of the geosciences. It covers a wide range of sub-disciplines in the solid earth geosciences, with emphasis on observational geology, mineralogy and palaeontology. In doing so it provides a niche for interdisciplinary papers on regional geology that can inform our understanding of global geological processes, as well as more wide-ranging studies on the fundamental principles of the earth sciences.

The Natural History of Igneous Rocks
  • Alfred Harker
  • Published online:
    05 March 2012
    Print publication:
    19 May 2011
    First published in:
    1909
  • Alfred Harker (1859–1939) was a prominent petrologist who spent his career at St John's College, Cambridge, lecturing on and researching rock formations and related geological activity. He was elected a fellow of the Royal Society in 1902, and was president of the Geological Society from 1916 to 1918. He used his Cambridge lectures as the foundation for this book (first published in 1909), offering an introduction to the development of rocks and related volcanic activity. With more than one hundred diagrams of various aspects of geological formations, this work also provides a visual guide to the location and formation of igneous rocks. Over the course of the work, he covers the themes of vulcanicity, rock structure, crystallization, the role of magma and the principles of rock classification, giving a broad picture of the field of petrology around the beginning of the twentieth century.

Page 1305 of 1306