Determination of (226)Ra in produced water by liquid scintillation counting.

It is proposed a method for the determination of (226)Ra in offshore platform liquid effluent samples (produced water). The method is based on a two-phase liquid scintillation counting system and allows for the direct and simple determination of (226)Ra content. Samples with high barium content may also have high (226)Ra concentration. Therefore, the sample volume is based on the barium concentration and ranges from 10 mL to 100 mL. Our new method was tested using multiple real samples and was compared with the BaSO4 precipitation method. The results based on the LSC were 30% higher than the precipitation method, which is attributed to the self-absorption of alpha particles in the BaSO4 precipitate. The determination of both (226)Ra and (228)Ra in the liquid effluent of offshore oil platforms is mandatory in Brazil. Thus, a second method of accurately assessing (228)Ra content remains necessary.

(210)Polonium and (210)lead content of marine birds from Southeastern Brazil.

In this study, we report the (210)Po and (210)Pb concentrations of bone, muscle and liver samples that were obtained from twelve different marine bird species stranded on beaches in the central-north region of Rio de Janeiro State. Both radionuclides were highly concentrated in the liver samples; however, the lowest mean (210)Po/(210)Pb activity ratio (1.3) was observed in bones compared with liver and muscle (16.8 and 13.8, respectively). Among the species that were studied, Fregata magnificens, with a diet based exclusively on fish, had the lowest (210)Pb and (210)Po concentrations and the lowest (210)Po/(210)Pb activity ratio. The (210)Po concentrations in Puffinus spp. liver samples followed a log-normal distribution, with a geometric mean of 300 Bq kg(-1)wet weight. Only two references pertaining to (210)Po in marine birds were found in a Web of Science search of the literature, and each study reported a different concentration value. The values determined in this experiment are consistent with those in one of the previous studies, which also included one of the species studied in this work. No values for (210)Pb in marine birds have been published previously.

210Polonium content of small cetaceans from Southeastern Brazil.

The (210)Po concentration of muscle and liver samples obtained from dolphins stranded on beaches in the Southeastern region of Rio de Janeiro State was analyzed in the present study. The samples were primarily obtained from "Franciscana" (Pontoporia blainvillei) and "Guiana" dolphins (Sotalia guianensis); however, samples from four other species were also evaluated. The (210)Po concentration of muscle samples obtained from "Franciscana" dolphins (66.7±6.7, n=8)Bq kg(-1)w.w. was greater than that of "Guiana" dolphins (25.3±5.7, n=8)Bq kg(-1)w.w. due to differences in the diets of these species. Alternatively, the (210)Po concentrations of liver samples obtained from different species were statically equivalent. Compared to the results described in the literature, the muscle samples evaluated in the present study displayed lower (210)Po concentrations, except for those obtained from "Franciscana" dolphins, which exhibited similar values. For "Franciscana" and "Guiana" dolphins, a clear relationship between the (210)Po concentration of muscle and liver samples and the size of the dolphin was not observed.

Geochronology of anthropogenic radionuclides in Ribeira Bay sediments, Rio de Janeiro, Brazil.

Ribeira Bay is located approximately 130 km south of the city of Rio de Janeiro and receives discharges of liquid effluent from the Angra dos Reis nuclear power plant (NPP) site, where two pressurized water reactors are located. To test whether the presence of anthropogenic radionuclides in sediments in Ribeira Bay could be correlated to the NPP operations, we sampled seven sediment cores and determined accumulation rates and chronologies. Only one sediment core did not exhibit a superficial mixing layer; this sample was used for dating purposes. Cesium-137 and (207)Bi were observed in this sediment profile, but their presence was associated with atmospheric fall-out rather than the nearby NPP. The exponential decay of (210)Pb concentration with sediment layer depth was verified below a superficial mixing layer for all other sediment cores. Calculated accumulation rates ranged from 1.2 mm y(-1) in the inner bay to 6.2 mm y(-1) close to its entrance.

Use of multitracers for the study of water mixing in the Paraíba do Sul River estuary.

Multitracers were used to study water mixing in the Paraíba do Sul River estuary region in August 2007 (dry season) and March 2008 (rainy season) and to evaluate the reach of the river plume in the direction of the open ocean. Two sampling campaigns were carried out, each in a different season. Based on these results, it was possible to conclude that the multitracers used in this study (salinity, Si, Ba and U, as well as the radium isotopes 223Ra, 224Ra, 226Ra and 228Ra) presented satisfactory results toward defining the plume reach and determining the residence time and water-mixing processes in the estuary. A strong correlation was observed between tracers and the distance to the coast. During the low river water discharge period, the riverine water took about 10 days to reach open ocean waters (salinity approximately 35). During the rainy period this value decreased to 6 days. Based on the radium results, it was possible to calculate diffusion coefficients (K(h)) of 23 km(2) d(-1) and 38 km(2) d(-1) for 224Ra and 223Ra, respectively, during the dry season (winter). Values of 65 km(2) d(-1) and 68 km(2) d(-1) for 223Ra and 224Ra, respectively, were found for the rainy period (summer).

Metal concentrations, fluxes, inventories and chronologies in sediments from Sepetiba and Ribeira Bays: a comparative study.

Three sediment cores were sampled at Sepetiba Bay and four cores at Ribeira Bay, Rio de Janeiro State, Brazil. Sediment accumulation rates and chronologies were obtained from (210)Pb activity-depth profiles. Sediment accumulation rates in Ribera Bay ranged from 1.2 mm y(-1) in the inner bay to 2.6 mm y(-1) close to its entrance. In Sepetiba Bay two sediment accumulation rates were observed: a lower rate of 0.35 cm y(-1) before the 1960s and 0.76 cm y(-1) since then. The cause of this change is due to the construction of the Santa Cecília impoundment (1955) that brings water from the Paraíba do Sul Basin into the Guandu River, which increased its flow from the original 20 m(3)s(-1) to 160 m(3)s(-1). Concentration of 44 elements was obtained by ICP-MS after total dissolution of samples from two selected cores. The relative differences between the concentrations of crustal elements, such as Al, Fe and Ti are only about 20% (p<0.05). Cd and Zn are 15 and four times larger in Sepetiba Bay than in Ribeira Bay, respectively. Other major and minor elements show lower statistically significant differences. The enrichment factors and metal inventories show that Sepetiba Bay can be considered polluted with Bi, Cd, Cr, Cu, Sb and Zn. Particularly, Cd and Zn present concentrations three and four times higher than the Brazilian existing limits.

Uranium isotopic ratio determination in urine using flow-injection ICP-MS: a tool for emergency monitoring.

An inductively coupled plasma mass spectrometry-based method is presented aimed at total uranium concentration and atomic ratio determination. The method includes flow-injection uranium separation based on TRU Eichrom extraction chromatographic cartridges. The method was tested with urine interlaboratorial exercise samples and certified reference materials (NBL-CRM-U020A and NBL-CRM-U050) providing reliable results. The proposed methodology was also applied to urine samples obtained after an incident at a nuclear facility. The obtained (235)U/(238)U and (234)U/(238)U atomic ratios in the urine of an exposed worker were equal to those observed for an enriched uranium solution from the same origin.

Application of ICP-QMS for the determination of plutonium in environmental samples for safeguards purposes.

Aiming to determine the plutonium amount as well as its isotopic composition, in particular, in swipe samples for safeguards purposes, an analytical method was developed with a plutonium separation step based on extraction chromatography using 2 cm TEVA columns and detection with quadrupole ICP-MS applying an ultra-sonic nebulizer coupled with membrane desolvation system. The method was successfully applied to New Brunswick plutonium certified reference materials as well as to Lawrence Livermore National Laboratory round robin samples, based on the round robin samples provided by the Institute for Reference Materials and Measurements (Belgium), as part of the Regular European Interlaboratory Measurement Evaluation Programme (REIMEP), campaign 16 (isotopic abundances of plutonium in plutonium nitrate samples), with a total plutonium amount between 1 and 0.25 ng per sample. After the introduction of an additional separation step, it was also possible to carry out precise and accurate total plutonium, (240)Pu/(239)Pu, (241)Pu/(239)Pu and (242)Pu/(239)Pu atom ratios determination in sediment sample showing its applicability to environmental samples in general, reaching a detection limit equivalent to 5 mBq(239)Pu kg(-1).

Exposure of workers in a mineral processing industry in Brazil.

In Brazil there are many regions where the extraction mining and processing of ores containing elements of great economical importance as tin, niobium and tantalum. Some of these ores have uranium and thorium natural decay series associated. This study was carried out in a niobium mine, where is obtained concentrates of niobates-tantalates, cassiterite and zirconite. The aim of this study is the evaluation of the occupational exposure to uranium, thorium, niobium and tin through urine bioassay data. In order to have it, 105 urine samples were analysed: 17 samples of exposed workers collected after a working day, 49 samples of exposed workers collected before a working day and 39 samples of local non-exposed people, assigned as a control group. The samples were analysed by mass spectrometry. The obtained results showed that the average concentration of Nb, Sn and U in the exposed group is statistically higher than those found in the control group indicating an occupational exposure. For Th there were no statistically difference between the exposed and the control group.

234U and 230Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples.

A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference sample and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. Samples from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky(-1) was calculated. Samples from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.