Coupled anthropogenic anomalies of radionuclides and major elements in estuarine sediments

Concentrations of fertilizer industry-derived P (up to 3.4%), Ca (up to 6.1%), Ra-226 (up to 744 Bq kg(-1)) and Pb-210 (up to 1317 Bq kg(-1)) at least one order of magnitude above natural levels were recorded in a sediment core from Morrao River estuary (SE Brazil). Unsupported Pb-210 (=total Pb-210- Ra-226) activities unexplained by atmospheric fallout and deviations from the radionuclides secular equilibrium also indicated strong anomalies. Anomalous constituents were positively correlated with each other and negatively correlated with clay mineral-bearing elements. These negative correlations were explained by a depletion of natural sediment constituents due to a dilution caused by elevated inputs of steel industry-derived elements (mainly by Fe levels up to 24%). Absolute data and normalizations by a proxy for clays (Al) and anthropogenic Fe evidenced variabilities in the quality of coastal and land-derived sediment inputs, mainly due to changes in the relative contributions from industrial sources. (C) 2008 Elsevier Ltd. All rights reserved.