Estimates of the resistance to chemical transport posed by the deep‐sea boundary layer1,2

Abstract

A strategy has been developed to permit the in situ calibration of measurements made with benthic chambers of chemical fluxes across the sediment‐water interface. The resistance to chemical transport posed by the boundary layer is estimated using chemical transport techniques in benthic flux chamber mock‐ups and on the sea floor. Dissolution from gypsum (alabaster) plates is measured both inside and outside the flux chambers. CaCO3 dissolution and radioisotope uptake techniques are suitable for laboratory and deep‐sea calibration of benthic fluxes. Broadly concordant resistance estimates have been achieved within flux chambers with these three quite different approaches. An estimate of 470 µ for the equivalent stagnant boundary film thickness has been made by the alabaster method on the sea floor at MANOP site H in the eastern Pacific. The transport of Mn2+ from the bottom waters to site H nodules, if controlled by diffusion through a film of this thickness, would be sufficient to explain their growth rates.