Models for Studying the Occurrence of Lead and Zinc in a Deltaic Environment

Abstract

The relationships between the Pb and Zn content of sediments of the Niger Delta, West Africa, and Eh, organic content of the sediments, content of carbonate shell substance, Mn, P, S, and depth of origin of sample have been studied by the multivatiate statistical method of canonical correlation. The first model weighs the “predictor” variables of organic content and depth, in negative association, against a “response” vector dominated by P, negatively associated with Pb, Mn and S. The correlation of this vector with the original variables brings out the underlying relationship (Mn, -P, 2S). A second statistically significant, and almost equally important relationship for these data present the correlation between organic content and depth, in positive association, bound to a response vector dominated by Pb, Mn and P. The underlying relationship is shown to be between all elements in relation to depth and content of organic substance. The distribution of Pb and Zn is described by this vectorial association. The predictor and response structures of this root seem to express the distribution of the organic sedimentary component and the chemical constituents. A third, although nonsignificant, interrelationship weighs shells, with their soft parts, against Pb, negatively associated with P and S. Eh is of no account in the first two models but plays a certain role for the third root. A fourth set of non-significant canonical variates may represent random variation in the Eh determinations. Although the bivariate correlation coefficient between Pb and Zn is high, there is a difference in part of their patterns of distribution in our material.