A sediment core from an estuarine area receiving drainage from the highly industrialized Cubatão River basin (SE Brazil) showed 226Ra and 210Pb activities up to 80 and 213 Bq kg−1, respectively, which are greater than activities considered as regional background levels. Radionuclides and the elevated phosphorus concentrations (up to 0.3% sediment dry weight) found along the sediment core were significantly correlated with each other, indicating source similarity. These results indicate that 226Ra and 210Pb activities are affected by fertilizer industry-derived inputs in addition to natural sources. This interpretation was supported by 210Pb/226Ra ratios (found to be between 2.6 and 3.9) that indicate disequilibrium between 226Ra and its decay product 210Pb, as expected for phosphogypsum-affected sediments.
Sanders, LM, Sanders, CJ, Luiz-Silva, W, Machado, W, Silva-Filho, EV & Patchineelam, SR 2011, 'Anthropogenic source assessment of 226Ra and 210Pb in a sediment core from the Cubatão River estuary (SE Brazil)', Journal of Radioanalytical and Nuclear Chemistry, vol. 287, no. 3, pp. 729-732.
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