Gr. Fones et al., High-resolution metal gradients measured by in situ DGT/DET deployment in Black Sea sediments using an autonomous benthic lander, LIMN OCEAN, 46(4), 2001, pp. 982-988
DET (Diffusive equilibration in thin films) and DGT (diffusive gradients in
thin films) have been deployed in situ using an autonomous benthic lander
to measure concentrations and induced fluxes of Fe and Mn (DET/DGT) and tra
ce metals (DGT) in pore waters at millimeter spatial resolutions. The newly
developed deployment system is described, and based on these first results
, its strengths and weaknesses are discussed. Deployments were made in the
Western Black Sea in shelf sediments overlain by well-oxygenated water at a
water depth of 77 m. Maxima of the redox-sensitive metals at 4 and 8 cm de
ep within the sediment indicated that two zones of reduction dominated the
geochemistry. Sharp, but systematic, features were superimposed on this gen
eral picture and were well replicated in the profiles of Mn, Co, and Cd, bu
t the sharp features in the Fe profile were offset from those of the others
elements by several millimeters. Detection of this functional discriminati
on between Fe and Mn as regulators of trace metals would not have been poss
ible using more conventional sampling procedures.