Determination of High Resolution Pore Water Profiles of Trace Metals in Sediments of the Rupel River (Belgium) using Det (Diffusive Equilibrium in Thin Films) and DGT (Diffusive Gradients in Thin Films) Techniques

Abstract

Abstract. The techniques of diffusional equilibrium in thin films (DET) and diffusional gradients in thin films (DGT) were used to obtain high resolution pore water profiles of total dissolved and labile trace (mobilizable) metals in the sediments of the Rupel River, Belgium. DGT measures labile metal species in situ by immobilizing them on a resin gel after diffusion through a diffusive gel whereas for DET an equilibrium is established between the DET gel and the pore water. Concentrations of Pb and Zn obtained by DGT were in good agreement with the results obtained by centrifugation, and thus were well buffered by rapid equilibrium with the solid phase, whereas Fe, Mn and Cd were very tightly bound to the sediment phase and large differences were observed between the labile and the total metal concentrations. Cu, Zn, Co and Ni show intermediated behavior.Good correlations were found between the profiles of As and Fe and Mn and Co for DET as well as DGT showing a close link between the geochemical behavior of these elements. Cu, Zn, Pb and Cd are also influenced by the reductive mobilization of Fe and Mn oxides but are also closely linked to the bacterial degradation of organic matter in the surface sediments as to the precipitation of metal sulfides in the deeper layers.

Influence of the Iron-Reducing Bacteria on the Release of Heavy Metals in Anaerobic River Sediment

“…6). The same associations have been observed in sediment pore water: dissolved Ni and Cu increased where there was Fe and Mn reduction (Leermakers et al 2005). As a consequence, metals adsorbed or co-precipitated on iron oxides were released during their reduction as observed in previous studies (Francis and Dodge 1990;Bousserrhine et al 1999aBousserrhine et al , 1999bQuantin et al 2001).…”

Spatial variation of redox and trace metal geochemistry in a minerotrophic fen

“…FMO, which are formed under oxic conditions and are reductively dissolved in the suboxic zone, can sequester trace metals, both via adsorption and coprecipitation (Dzombak and Morel 1990;Hamilton-Taylor and Davison 1995;Tonkin et al 2004). Thus, reductive dissolution can release not only dissolved Mn(II) and Fe(II) to pore waters, but also associated trace metals, potentially making them more bioavailable and mobile (Balistrieri et al 1992a, b;Kerner and Wallmann 1992;Davison 1993;Tessier et al 1996;Hamilton-Taylor et al 1999;Fredrickson et al 2001;Zachara et al 2001;Peltier et al 2003;Leermakers et al 2005;Cooper et al 2006). In the sulfidic zone, many trace metals, especially chacophiles like Pb, Zn, Cd or Cu, are often present in metal sulfide phases (Morse and Arakaki 1993;Huerta-Diaz et al 1993, 1998Rickard et al 1995;Morse and Luther 1999).…”

Sulfur Cycling and the Sulfurization of Humic and Fulvic Acids in the Sediments of the rivers Rupel (Belgium) and Authie (northern France)

“…The present paper compares the distribution of dissolved and sedimentary S species in sediments accumulated on the tidal banks of two western European rivers, the heavily polluted River Rupel (Belgium) and the pristine River Authie (northern France), that differ in pollution levels. Some of the results presented herein have been published before (Leermakers et al 2005;Lojen et al, submitted) but were not discussed in light of the sulfurization of humic and fulvic acids. Stable isotopic compositions of dissolved sulfate, as well as sedimentary S species, i.e., acid volatile sulfide pool (AVS), pyrite, elemental S (S 0 ) and sulfur bound to fulvic (FAS) and humic acids (HAS), were used as natural tracers to estimate the formation sequence of sedimentary S species as well as potential agents for the sulfurization of organic substrates.…”