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Mediterranean nutrient balance and episodes of anoxia
Author(s) -
Sarmiento Jorge L.,
Herbert Timothy,
Toggweiler J. R.
Publication year - 1988
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/gb002i004p00427
Subject(s) - mediterranean climate , sill , nutrient , oceanography , limiting , mediterranean sea , environmental science , hypoxia (environmental) , geology , mediterranean basin , sediment , ecology , oxygen , biology , chemistry , paleontology , geochemistry , mechanical engineering , organic chemistry , engineering
We examine the causes of anoxia in regions such as the Eastern Mediterranean, which have exchange over sills with adjacent basins. Box models show that the concentration of the limiting nutrient is the major determinant of deep oxygen levels. The most effective way of increasing nutrient concentrations to the point where anoxia occurs is to change the flow pattern across the sills ventilating the basins. With a sill exchange pattern such as that in the present Strait of Sicily, it is difficult to obtain anoxia in the Eastern Mediterranean without also driving the Western Mediterranean to low oxygen and high nutrient levels. Episodes of anoxia in the Eastern Mediterranean are associated with a freshening of surface waters. A reversal in flow directions, presumably resulting from the observed freshening, will inevitably lead to anoxia associated with increased sediment burial rates of the limiting nutrient and will leave the Western Mediterranean largely unaffected, in keeping with the observational evidence.