Fluid displacive resin embedding of laminated sediments: preserving trace metals for high-resolution paleoclimate investigations

Abstract

For the high-resolution study of trace metal profiles in laminated anoxic sediments, a specially adapted method of resin embedding has been developed. Fluid displacement is the preferred means of sediment dehydration, offering optimum structural preservation and facilitating desalination. Exchanges of deionized water, acetone, and low-viscosity resin are performed in an oxygen-deficient atmosphere to maintain anoxia in the sediments. Analysis of the rinsing fluids indicates both efficient removal of brine salts and minimal dissolution of redox-sensitive trace metals. This contrasts with oxic fluid displacement experiments, in which several metals appear to be removed from the solid phase during desalination. Laser Ablation-Inductively Coupled Plasma- Mass Spectrometry (LA-ICP-MS) scanning of the embedded blocks shows that the adapted preparation viably preserves both the redox-sensitive chemistry and physical structure of the sediment.