Copyright © 2013 Elsevier Inc. All rights reserved. Chapter 1 Introduction Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 1.1 Annual cycles of CO2 and O2 in the atmosphere. Changes in the concentration of O2 are expressed relative to concentrations of nitrogen (N2) in the same samples. Note that the peak of O2 in the atmosphere corresponds to the minimum CO2 in late summer, presumably due to the seasonal course of photosynthesis in the Northern Hemisphere. Source: From Ralph Keeling, unpublished data used by permission. Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 1.2 An 800,000-year record of CO2 and temperature, showing the minimum temperatures correspond to minimum CO2 concentrations seen in cycles of ~120,000 periodicity, associated with Pleistocene glacial epochs. Source: From Luthi et al. (2008) Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 1.3 The interaction between the carbonate and the silicate cycles at the surface of Earth. Long-term control of atmospheric CO2 is achieved by dissolution of CO2 in surface waters and its participation in the weathering of rocks. This carbon is carried to the sea as bicarbonate , and it is eventually buried as part of carbonate sediments in the oceanic crust. CO2 is released back to the atmosphere when these rocks undergo metamorphism at high temperature and pressures deep in Earth. Source: Modified from Kasting et al. (1988). Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 1.4 A matrix showing how cellular metabolisms couple oxidation and reduction reactions. The cells in the matrix are occupied by organisms or a consortium of organisms that reduce the element at the top of the column, while oxidizing an element at the beginning of the row. Source: From Schlesinger et al. (2011). Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 1.5 An ecosystem-level experiment in which a lake was divided and one half (distant) fertilized with phosphorus, while the basin in the foreground acted as a control. The phosphorus-fertilized basin shows a bloom of nitrogen-fixing cyanobacteria. Source: From Schindler (1974); www.sciencemag.org/content/184/4139/897.short. Used with permission. Copyright © 2013 Elsevier Inc. All rights reserved.

Copyright © 2013 Elsevier Inc. All rights reserved. TABLE 1.1 Movement of Selected Elements through the Atmospher Copyright © 2013 Elsevier Inc. All rights reserved.