Sedimentary nutrient regeneration on the oligotrophic eastern Mediterranean continental shelf
1988
Christensen, J P | Goldsmith, V | Walline, P | Schneller, A | El Sayed, Sz
Porewater nutrient concentrations and nutrient fluxes between the sediments and overlying waters were determined with cores from an 80 m site on the Israeli shelf. Silicate fluxes predicted from porewater profiles with vertical molecular diffusion were 5.5-fold less than those measured suggesting the occurrence of bioturbation. A two-zoned diagenetic model, including bioturbation and molecular diffusion in the upper 4 cm of sediments but only molecular diffusion below, sedimentation, and a first-order dissolution rate where the rate constant was much greater in the bioturbated zone than at depth, could explain both the near-exponential profile shape and the large measured flux. Burial and denitrification could remove nitrogen at rates as great as 25% of the total phytoplankton N demand. Thus sediments appear to remove large quantities of nitrogen from this oligotrophic shelf ecosystem.
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