Speciation of soluble manganese in lakewater with Chelex-100 and polyacrylate resin, XAD-7

Abstract

Two fractions of (soluble) manganese in Lake Ontario water have been detected and measured with the aid of sequential preconcentration on the polyacrylic ester resin, XAD-7, and Chelex-100. One fraction, consisting of free Mn(II), was retained on the XAD-7 column; the second fraction, consisting of one or more unidentified forms, was retained on Chelex-100. After elution from the columns, the concentration of manganese in each fraction in the lakewater was determined by graphite-furnace AAS. Because both fractions are retained by Chelex-100, the second fraction could also be determined by difference on passage of two separate aliquots through Chelex-100 and XAD-7. Analysis of samples from three locations in the western basin of Lake Ontario showed that about 12–22% of total (soluble) manganese was present as free Mn(II).