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Germanium and silicon in rivers of the Orinoco drainage basin


CONTINENTAL weathering and mid-ocean-ridge hydrothermal circulation are the two main processes that release dissolved silicon to the ocean. It has been hypothesized1 that temporal variations in the relative strengths of these two processes might be estimated from the Ge/Si ratio of opal in marine sediments, because the chemistry of germanium is similar to that of silicon2–5. We analysed river water from the Orinoco basin and soils from Venezuela and Panama for germanium and silicon, to determine the relationship between river Ge/Si ratios, drainage basin lithology and chemical-weathering intensity. Our results, presented here, indicate that chemical-weathering intensity, defined as the fraction of original bedrock silicon dissolved during continental weathering, is related to the Ge/Si ratio in river water and is inversely related to river silicon concentrations. Changes in global climate, sea level or patterns of plate-tectonic interactions could change chemical-weathering intensity and complicate the interpretation of the marine opal Ge/Si record.

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  1. 1

    Froelich, P. N. & Andreae, M. O. Science 213, 205–207 (1981).

    ADS  CAS  Article  Google Scholar 

  2. 2

    Cotton, F. A. & Wilkinson, G. Advanced Inorganic Chemistry (Wiley-Interscience, New York, 1972).

    Google Scholar 

  3. 3

    Froelich, P. N., Hambrick, G. A., Andreae, M. O., Mortock, R. A. & Edmond, J. J. geophys. Res. 90, 1133–1141 (1985).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Mortlock, R. A. & Froelich, P. N. Geochim. cosmochim. Acta 51, 2075–2082 (1987).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Murnane, R. J., Leslie, B., Hammond, D. A., Stallard, R. F. Geochim. cosmochim. Acta 53, 2873–2882 (1989).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Bernstein, L. R. Geochim. cosmochim. Acta 49, 2409–2422 (1985).

    ADS  CAS  Article  Google Scholar 

  7. 7

    Martin, J. M. & Meybeck, M. Marine Chem. 7, 173–206 (1979).

    CAS  Article  Google Scholar 

  8. 8

    Stallard, R. F. in The Chemistry of Weathering (ed. Drever, J. I.) 293–316 (Reidel, Dordrecht, 1985).

    Book  Google Scholar 

  9. 9

    Stallard, R. F. in Physical and Chemical Weathering in Geochemical Cycles (eds Lerman, A. & Meybeck, M.) 225–246 (Kluwer Academic, Dordrecht, 1988).

    Book  Google Scholar 

  10. 10

    Stallard, R. F. & Edmond, J. M. J. geophys. Res. 88, 9671–9688 (1983).

    ADS  CAS  Article  Google Scholar 

  11. 11

    Stallard, R. F. & Edmond, J. M. J. geophys. Res. 92, 8293–8302 (1987).

    ADS  CAS  Article  Google Scholar 

  12. 12

    Murnane, R. J. thesis, Princeton Univ. (1988).

  13. 13

    Novokahatskiy, I. P., Kalinin, S. K. & Zamuayina, G. M. Geochem. Int. 4, 1192–1196 (1967).

    Google Scholar 

  14. 14

    Meybeck, M. Rev. Geol. Dyn. Geogr. Phys. 21, 215–246 (1979).

    CAS  Google Scholar 

  15. 15

    Mortlock, R. A. & Froelich, P. N. Science 231, 43–45 (1986).

    ADS  CAS  Article  Google Scholar 

  16. 16

    Murnane, R. J. & Stallard, R. F. Paleoceanography 3, 461–469 (1987).

    ADS  Article  Google Scholar 

  17. 17

    Andreae, M. O. & Froelich, P. N. Analyt. Chem. 553, 287–291 (1981).

    Article  Google Scholar 

  18. 18

    Schneider, W. A. Jr & Sandell, E. B. Mikrochim. Acta 2, 263–268 (1954).

    Article  Google Scholar 

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Murnane, R., Stallard, R. Germanium and silicon in rivers of the Orinoco drainage basin. Nature 344, 749–752 (1990).

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