Cu and Zn concentration gradients created by dilution of pH neutral metal-spiked marine sediment: a comparison of sediment geochemistry with direct methods of metal addition.
The geochemistry of artificially metal contaminated sediments prepared using three methods of metal-spiking was compared in this study. Marine sediments with a gradient of Cu and Zn concentrations were prepared by direct-spiking without and with pH-adjustment to pH 7, and also by serial dilution of direct-spiked sediment (4000 microg g(-1), pH 7 adjusted) with uncontaminated sediment. Porewater concentrations of Cu, Zn, Fe, and Mn in direct-spiked sediments without pH adjustment were orders of magnitude higher than the equivalent sediments adjusted to pH 7 or those prepared by the serial dilution method. Despite pH-adjustment, porewater Cu and Zn concentrations of direct-spiked sediment remained higher than concentrations observed within metal-contaminated natural sediment. The serial dilution of metal-spiked, pH-adjusted sediment substantially decreased Cu and Zn partitioning to the dissolved phase, and minimized the variation of potential competitive ions (H+, Fe2+, Mn2+) over the entire gradient of spiked Cu and Zn concentrations. Metal concentration gradients created using serial dilution of Cu- and Zn-spiked, pH-adjusted sediments produced porewater Cu or Zn, Fe, and Mn concentrations that resemble sediment-porewater partitioning (Cu, Zn, Fe, Mn) typical of metal-contaminated natural sediments. This method is recommended for whole-sediment toxicology studies.
Hutchins
Colin M
CM
Australian Rivers Institute, Griffith University, PMB 50, Gold Coast Mail Centre, Queensland 9726, Australia. colin.hutchins@umontreal.ca
Teasdale
Peter R
PR
Lee
Shing Yip
SY
Simpson
Stuart L
SL
D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000032:analysis*; D010084:Oxidation-Reduction; D016062:Porosity; D014874:Water Pollutants, Chemical / Q000032:analysis*
D019216:Metals, Heavy; D014874:Water Pollutants, Chemical