Manganese species migration in soil at the Sabine National Wildlife Refuge, Louisiana

A modified sequential extraction procedure was employed to speciate the chemical forms of Mn in sediment using flame atomic absorption spectrophotometry. Concentrations were determined in five different fractions for each sample (Mn in the exchangeable form, bound to carbonates, bound to Mn/Fe oxides, bound to organic matter and in the residual form). The determinations were made for sediments obtained from the Sabine National Wildlife Refuge while a marshland reclamation project was being conducted. Sediment samples were taken from Ship Channel dredge spoils (thought to be contaminated), an old reclamation site, a new reclamation site and a reference site. The results indicated that the Ship Channel sediments were not contaminated, but revealed an Mn “pumping” model, which proposes that additional Mn added to a similar site is concentrated near the surface soil layers by environmental conditions, which may be a cause of the observed slow recovery of vegetation at one of the more recently developed sites.