Unexpected changes in the oxic/anoxic interface in the Black Sea

Abstract

THE Black Sea is the largest anoxic marine basin in the world today1. Below the layer of oxygenated surface water, hydrogen sulphide builds up to concentrations as high as 425 μM in the deep water down to a maximum depth of 2,200 m (ref. 2). The hydrographic regime is characterized by low-salinity surface water of river origin overlying high-salinity deep water of Mediterranean origin1,3. A steep pycnocline, centred at about 50 m is the primary physical barrier to mixing and is the origin of the stability of the anoxic (oxygen/hydrogen sulphide) interface. Here we report new observations, however, that indicate dramatic changes in the oceanographic characteristics of the anoxic interface of the Black Sea over decadal or shorter timescales. The anoxic, sulphide-containing interface has moved up in the water column since the last US cruises in 1969 and 1975. In addition, a suboxic zone overlays the sulphide-containing deep water. The expected overlap of oxygen and sulphide was not present. We believe that these observations result from horizontal mixing or flushing events that inject denser, saltier water into the relevant part of the water column. It is possible that man-made reduction in freshwater inflow into the Black Sea could cause these changes, although natural variability cannot be discounted.

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References

  1. 1

    Caspers, H. Geol. Soc. Am. Mem. 67, 803–890 (1957).

    Google Scholar 

  2. 2

    Brewer, P. G. Woods Hole Oceanogr. init. Tech. Note 71–65 (1971).

  3. 3

    Spencer, D. W. & Brewer, P. G. J. geophys. Res. 76, 5877–5892 (1971).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Murray, J. W. & Izdar, E. Oceanogr. Mag. (in the press).

  5. 5

    Spencer, D. W., Brewer, P. G. & Sachs, P. L. Geochim. cosmochim. Acta 36, 71–86 (1972).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Gagosian, R. B. & Heinzer, F. Geochim. cosmochim. Acta 43, 471–486 (1979).

    ADS  CAS  Article  Google Scholar 

  7. 7

    Karl, D. M. Limnol. Oceanogr. 23, 936–949 (1975).

    ADS  Article  Google Scholar 

  8. 8

    Fashchuk, D. Ya. & Ayzatullin, T. A. Oceanology 26, 171–178 (1986).

    Google Scholar 

  9. 9

    Boguslavskiy, S. G., Zhorov, V. A. & Novoselov, A. A. Morsk. gidrofiz. zhurn 1, 54–58 (1985).

    Google Scholar 

  10. 10

    Novoselov, A. A., Sovga, Ye. Ye., Fashchuk, D. Ya., Khomutov, S. M. & Sheremet'yeva, A. I. Ocenology 27, 304–307 (1987).

    Google Scholar 

  11. 11

    Leonov, A. V. & Ayzatullin, T. I. Oceanology 27, 174–178 (1987).

    Google Scholar 

  12. 12

    Zhorov V. A. Geochim. Int. 65–73 (1982).

  13. 13

    Murray J. W. School of Oceanography spec. Rep. No. 108 (Univ. of Washington, 1988).

  14. 14

    Brewer, P. G. & Murray, J. W. Deep Sea Res. 20, 803–818 (1973).

    CAS  Google Scholar 

  15. 15

    Vinogradov, M. Te., Shushkina, E. A., Flint, M. V. & Tumantsev, N. I. Oceanology 26, 222–228 (1986).

    Google Scholar 

  16. 16

    Bol'shakov, V. S., Tolmazin, D. M. & Rozengurt, M. Sh. Izvetia Acad. Sci. U.S.S.R. Geophys. Ser. 6, 562–565 (1964).

    Google Scholar 

  17. 17

    Shaffer, G. Nature 321, 515–517 (1986).

    ADS  CAS  Article  Google Scholar 

  18. 18

    Rooth C. G. H. in Report on the Chemistry of Seawater. XXXIII (Univ. of Goteborg, 1986).

    Google Scholar 

  19. 19

    Tolmazin, D. Prog Oceanogr. 15, 217–276 (1985).

    ADS  Article  Google Scholar 

  20. 20

    Georgiev, Yu. S. in Okeanograficheskiye issledovaniya Chernogo Morya 105–113 (Naukova Dumka, Kiev, 1967).

    Google Scholar 

  21. 21

    Ovchinnikov, I. M. & Popov, Yu. I. Oceanology 27, 555–560 (1987).

    Google Scholar 

  22. 22

    Tolmazin, D. New Scientist 767–769 (1979).

  23. 23

    Tolmazin, D. Prog. Oceanogr. 15, 277–316 (1985).

    ADS  Article  Google Scholar 

  24. 24

    Emerson, S. et al. Geochim. cosmochim. Acta 46, 1073–1079 (1982).

    ADS  CAS  Article  Google Scholar 

  25. 25

    Tebo, B. M., Nealson, K. H., Emerson, S. & Jacobs, L. Limnol. Oceanogr. 29, 1247–1258 (1984).

    ADS  CAS  Article  Google Scholar 

  26. 26

    Anderson, J. J. & Devol, A. H. Deep Sea Res. 34, 927–944 (1987).

    ADS  CAS  Article  Google Scholar 

  27. 27

    Kremling, K. Mar. Chem. 13, 87–108 (1983).

    CAS  Article  Google Scholar 

  28. 28

    Anderson, J. J. & Devol, A. H. Estuar. Coast. mar. Sci. 1, 1–10 (1973).

    ADS  Article  Google Scholar 

Download references

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Murray, J., Jannasch, H., Honjo, S. et al. Unexpected changes in the oxic/anoxic interface in the Black Sea. Nature 338, 411–413 (1989). https://doi.org/10.1038/338411a0

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