Abstract

A high-resolution record of carbon isotope changes during the late Holocene was obtained in core GA-112 from the easternmost Mediterranean. Over the past 3600 yr, a gradual 13C-depletion trend shown by both planktonic and benthic foraminifera corresponds to a global rise in atmospheric CO2. The global and local trends suggest that aridification and biomass destruction in the Nile basin played a major role in the global CO2 rise in the late Holocene. Superimposed on the general δ13C trend are four mirror- image cycles in δ13C of planktonic and benthic foraminifera. Higher planktonic δ13C values reflect periods of high productivity off the coast of Israel. Simultaneously, decrease in the benthic δ13C values occurred because of degradation of higher organic-matter fluxes to the sediment. Therefore, large differences between the two records indicate periods of high productivity. The Eastern Mediterranean productivity fluctuations respond to a periodical replenishment of nutrients to the mixed layer via Nile runoff. Historical data of the Nile flood fluctuations for the past ∼1400 yr show a remarkable coincidence between high and low Nile floods and high and low Eastern Mediterranean productivity levels, which are correlated with the periodic monsoonal activity over the Nile headwaters.

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