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  • Author or Editor: C. Sanders x
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Abstract  

A sediment core was taken to determine if sediment accumulation rates could be conducted using 240+239Pu signatures in the coastal mangrove mudflats of southeastern Brazil. The results from this study show that 240+239Pu fallout activities are sufficient and well preserved in the coastal sediments of this region. Sediment accumulation rates determined from the 240+239Pu signatures were 4.4 mm/year and 4.1 from 210Pb (CIC) method. A sediment mixing coefficient rate was calculated using chlorophyll-a profile (9.5 cm2).

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Abstract  

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.

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