The association between biogenic and inorganic minerals and the amino acid composition of settling particles

Abstract

To test the hypothesis that calcium carbonate (rather than opal) carries most organic carbon to the deep sea, total hydrolysable amino acids (THAA) analysis was applied to deep sea (3000 m) sediment trap material from the Northeast Atlantic (PAP Site), a variable but intrinsically carbonate-dominated system. THAA were analyzed in conjunction with total organic carbon, biogenic silica, calcium carbonate, and inferred lithogenic fluxes. The THAA57 based degradation state of organic carbon could not be systematically explained by changes in the flux of different mineral phases which could only account for 16% of the observed variability. In addition amino acid parameters indicative of source organisms indicate diatom cell walls are an important residual component of organic carbon reaching the deep ocean; a finding supported by comparison with data from previous studies of diverse oceanic environments. Finally, during 2001 very high organic carbon fluxes were associated with elevated lithogenic fluxes and low organic matter degradation relative to surrounding years. In accordance with other recent experimental and observational studies the data indicates that under specific export scenarios lithogenic fluxes can act as highly significant mediators of organic carbon transfer to the deep-ocean.

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