TY - CHAP

T1 - New In-Situ Procedures for Measuring Trace Metals in Pore Waters.

AU - Zhang, H.

AU - Davison, W.

AU - Grime, G. W.

PY - 1995

Y1 - 1995

N2 - The most mobile and biological and chemically active fractions of trace metals in sediments are the dissolved components present in pore waters. Measuring metals in pore waters is complicated by the requirement for anoxic handling procedures. Due to the dynamic nature of sediment, steep concentration gradients extending over as little as 1 mm may develop at the sediment-water interface. New procedures for measuring metals in pore waters using polyacrylamide gels as in-situ probes are described. The gel can be used to establish a diffusive equilibration in a thin-film (DET). Because the film is typically less than 1 mm thick, equilibration is achieved within five minutes and insertion of the gel assembly causes minimal disturbance of sediment. An alternative procedure is to use a diffusive gradient in a thin-film (DGT), whereby a monolayer of chelating resin is incorporated at one side of the gel. Such a technique provides a kinetic measurement of labile species in solution. If the supply of metal from solid phase sediment to pore waters is fast enough, DGT provides a quantitative estimate of labile metal concentration. Alternatively, it measures directly the rate of supply of metal from solid phase to pore waters. As both DET and DGT are simple procedures capable of submillimetre spatial resolution, they provide previously unobtainable information on trace metal concentrations and fluxes. Furthermore, DGT has the potential to be used as a long-term monitor, providing mean concentrations of metals in sediment pore waters over periods of days, weeks, or even months.

AB - The most mobile and biological and chemically active fractions of trace metals in sediments are the dissolved components present in pore waters. Measuring metals in pore waters is complicated by the requirement for anoxic handling procedures. Due to the dynamic nature of sediment, steep concentration gradients extending over as little as 1 mm may develop at the sediment-water interface. New procedures for measuring metals in pore waters using polyacrylamide gels as in-situ probes are described. The gel can be used to establish a diffusive equilibration in a thin-film (DET). Because the film is typically less than 1 mm thick, equilibration is achieved within five minutes and insertion of the gel assembly causes minimal disturbance of sediment. An alternative procedure is to use a diffusive gradient in a thin-film (DGT), whereby a monolayer of chelating resin is incorporated at one side of the gel. Such a technique provides a kinetic measurement of labile species in solution. If the supply of metal from solid phase sediment to pore waters is fast enough, DGT provides a quantitative estimate of labile metal concentration. Alternatively, it measures directly the rate of supply of metal from solid phase to pore waters. As both DET and DGT are simple procedures capable of submillimetre spatial resolution, they provide previously unobtainable information on trace metal concentrations and fluxes. Furthermore, DGT has the potential to be used as a long-term monitor, providing mean concentrations of metals in sediment pore waters over periods of days, weeks, or even months.

KW - in-situ

KW - measurement

KW - polyacrylamide gel

KW - trace metals

KW - pore waters

KW - diffusive equilibration in thin-film (DET)

KW - diffusive gradient in thin-film (DGT)

KW - ion-exchange resin

M3 - Chapter

SN - 978-0-8031-5316-5

VL - STP 12

SP - 170

EP - 181

BT - Dredging, Remediation, and Containment of Contaminated Sediments

A2 - Demars, K. R.

A2 - Richardson, G. N.

A2 - Yong, R. N.

A2 - Chaney, R. C.

PB - ASTM Digigal Library

ER -