Speciation of Fe, Mn and Zn in surficial sediments from the Egyptian Red Sea coasts

Abstract

The use of two schemes (I and II) was compared for the fractionation of Fe, Mn and Zn in surficial sediments of the coastal regions of Egyptian Red Sea coasts. Scheme I measured the total oxide fraction. Scheme II, a detailed sequential extraction protocol, was used to distinguish oxide forms of the metal (Mn, poor crystalline Fe and crystalline Fe oxides). The data revealed that high percentage of Zn was concentrated in the residual fraction (lithogenic origin) in all sectors of the study. A high percentage of Mn was concentrated in the residual fraction in both of the Gulf of Aqaba and Red Sea proper samples. However, a high percentage of Mn was recorded in the non-residual form; 60.53% (anthropogenic origin) in the Suez Gulf samples. The recovery of Fe was efficient at most stations using Scheme II, and it was shown that most of the Fe was concentrated among residual, poor crystalline Fe oxide and crystalline Fe oxide fractions. Both Schemes I and II are recommended for speciation of Mn and Zn, but Scheme I is preferred since it has fewer analytical steps. However, Scheme 2 is strongly recommended for the determination of the Fe fractionation pattern. Principal component analysis was applied to the multivariate data derived from the geochemical analysis of 24 stations in the study area and the fractionation patterns of Fe, Mn and Zn associated with physico-chemical characteristics of the sediment are discussed.