Influence of major elements on heavy metal composition of river sediments

In the present study, the relationship between heavy metals (As, Cd, Cr, Cu, Hg, Pb, Ni, Sn and Zn) and major elements and the location and/geological substrate of 105 river sediments in Flanders was investigated. Factor Analysis was used to divide the dataset into four components: a first component including clay, organic matter, Na, Ca, K and Mg, a relationship between Fe, As and Cd, an anthropogenic factor (including Cu, Hg, Pb, Sn and Zn) and finally the pH and insoluble residue. Regression equations were constructed, using major elements such as Fe and Ca as independent variables, besides more classical explaining variables such as clay content (< 2µm fraction), organic matter content and pH. Most heavy metal concentrations could be predicted very well by the independent variables, except Zn, Se and Sn. The results from this study, performed on a dataset of 105 riverbed sediments, indicate that, besides organic matter and clay content, other variables such as the total Fe and Ca content can be relevant parameters to predict heavy metal concentrations in sediments. The more general applicability of the obtained regression equations should be verified, and the inclusion of Fe and Ca in regression equations that are applied for the standardization of total metal concentrations in soils and sediments, should be considered.