Use of normalized metal concentrations in the Mn oxides/hydrous oxides extraction phase of stream sediments to enhance the difference between a landfill emission plume and background

Normalized concentrations of Fe, Zn, Ba and Co bound to the Mn phase were determined using a ratio of metal concentration to Mn concentration. Metal concentrations were taken from a previous study which found elevated concentrations of heavy metals in the stream sediments in the vicinity of 2 landfills using a HN03 extraction of the whole sediment sample and geochemical phases. Results from the normalized metal concentrations for Zn, Fe and Ba showed a clearer distinction between background and emission plume regions along the stream compared to the same for the HN03 and Mn phase extractions. Lack of elevated concentrations and normalized concentrations for Co indicated the concentrations represented the background. The small distance used in the study could explain the lack of a decreasing trend of metal concentrations and normalized metal concentrations downstream in the emission plume of the sediments. Although Mn+2 2concentrations are known to be incorporated into the natural state of the Mn phase, these concentrations were thought to be small enough not to influence the results from the normalized concentrations. Non-selectivity of extractants and metal redistribution among chemical phases during extraction procedures are thought to be small and did not invalidate the results.