José Marcus Godoy

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.

226Ra and 228Ra in scale and sludge samples and their correlation with the chemical composition.

In order to contribute to a future waste management policy related to the presence of technologically enhanced natural occurring radioactive material (TENORM) in the Brazilian petroleum industry, the present work presents the chemical composition and the (226)Ra and (228)Ra content of sludge and scales generated during the offshore E and P petroleum activities in the Campos Basin, the primary offshore oil production region in Brazil. The (226)Ra and (228)Ra content on 36 sludge and scales samples were determined by gamma-spectrometry. Based on X-ray diffractometry results, a chemical analysis schema for these samples was developed. The results have shown that scales are 75% barium and strontium sulfates, with a mean (226)Ra and (228)Ra content of 106 kBq kg(-1) and 78 kBq kg(-1), respectively. On the other hand, sludge samples have a much more complex chemical composition than the scales. The (226)Ra and (228)Ra content in sludge also varies much more than the content observed in the scales samples and ranged from 0.36 to 367 kBq kg(-1) and 0.25 to 343 kBq kg(-1), respectively.

Natural radionuclides in Brazilian mineral water and consequent doses to the population.

Based on production data published by the Brazilian Mineral Water Producers Association, bottled mineral waters were bought at the market, covering, at least, 50% of the annual production of each Brazilian geographical region. 228Ra, 226Ra and 210Pb were analyzed and the weighted mean values obtained for Brazilian mineral waters were 0.097, 0.027 and 0.066 Bq l-1 respectively. Individual effective dose rate estimates due to ingestion of mineral water in Brazil were of the order of 10-100 microSv yr-1, depending on the geographical region. Based on the available data, it was also possible to evaluate the per caput effective dose rate and the highest value obtained was 4.3 microSv yr-1 for the northern region.

Trace metal contamination in mangrove sediments, Guanabara Bay, Rio de Janeiro, Brazil

The Guanabara Bay in Rio de Janeiro has undergone profound alterations of its natural environmental conditions. Metal concentration increase in sediments has been reported to be among these alterations. Trace-metal contamination and availability were studied in sediments of 3 mangrove areas of the bay. Cd, Zn, Pb, Ni, Cu and Al concentrations were determined in segments of sediment cores, after treatment with 1 mol L-1 HCl and with concentrated HNO3. Fe and Mn were determined in the leach with HNO3. Concentrations were low in comparison to those reported for Guanabara Bay and Cd showed up to 90% recovery in the HCl extract. Sediments found to be oxic to suboxic showed AVS concentrations in range of 0.07 (bottom) to 18.79 mmol g-1(sub-surface) indicating heterogeneity and apparent disequilibrium. Fe and Mn oxides, carbonates and organic matter may be the most important phases controlling metal availability and distribution.

Determination of total content and isotopic compositions of plutonium and uranium in environmental samples for safeguards purposes by ICP-QMS

The aim of this work was to determine the concentrations and isotopic compositions of plutonium and uranium in environmental samples for safeguards purposes. An analytical method was developed with a plutonium and uranium separation procedure based on extraction chromatography (using 2mL TEVA and UTEVA columns) and detection with a quadrupole ICP-MS applying an ultra-sonic nebulizer coupled with a membrane desolvation system. Starting from blank swipes, the background equivalent concentration (BEC) was 8fg for (239)Pu and 1ng (238)U. The method was successfully applied to certified reference materials as well as to round robin samples obtained in the framework of the inter-laboratory exercise program, promoted by the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), together with the US Department of Energy (USDOE). After the introduction of an additional ion-exchange separation step, the methodology was applied to the IAEA-384 sediment reference sample with precise and accurate total plutonium and uranium, (240)Pu/(239)Pu, (241)Pu/(239)Pu, (234)U/(238)U and (235)U/(238)U atomic ratio results.

Vehicular Emission Ratios of VOCs in a Megacity Impacted by Extensive Ethanol Use: Results of Ambient Measurements in São Paulo, Brazil

The São Paulo Metropolitan Area (SPMA) is a megacity with 20 million people and over 8 million vehicles. Over the past decade a large increase in biofuel usage, more notably ethanol by light-duty vehicles, has made Brazil, and in particular São Paulo, a unique case worldwide. This study presents the first assessment of emission ratios of a selected group of volatile organic compounds (VOCs) relative to carbon monoxide (CO) under ambient conditions. The VOCs studied here include aromatics such as benzene (1.03 pptv/ppbv CO), toluene (3.10 pptv/ppbv CO) and Oxygenated VOCs such as methanol (5.39 pptv/ppbv CO), acetaldehyde (3.93 pptv/ppbv CO), acetone (3.59 pptv/ppbv CO), methyl ethyl ketone (1.42 pptv/ppbv CO), and others. Despite the specificity of the fuel composition, emission ratios were in surprisingly close agreement with other megacities in Europe or in North America. Such results include species whose emission factors have been previously reported to decline (e.g., benzene) or increase (e.g., acetaldehyde) with ethanol usage. Furthermore, diurnal profiles and temperature analysis aid separating the primary anthropogenic, secondary or biogenic components of the species studied here. This study shows that a significant fraction of ethanol in gasoline blends does not result in a well-defined trend in VOC emission profile and certainly motivates further studies.

137Cs in marine samples from the Brazilian southeastern coastal region.

The present work presents the results of (137)Cs concentration in seawater, fish and sediments samples collect in 11 sampling points, crossing the Brazilian Southeastern coastal region, from Vitória (ES) to Santos (SP), on a routine basis from 1997 to 2002. This monitoring program was carried out by the Instituto de Radioproteção e Dosimetria (IRD/CNEN/MCT), in cooperation with the Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM/Brazilian Navy), aiming at determining artificial radionuclides in marine samples. Additionally to the (137)Cs results, (90)Sr concentrations in fish samples from 1998 to 2002 are also reported. The (137)Cs in seawater follows a lognormal distribution, with a geometric mean of 1.8 Bq m(-3) and a geometric standard deviation of 1.4 (n=54), decay corrected to June/2002. For (137)Cs levels in fish samples a geometric mean of 0.19 Bq kg(-1) and a geometric standard deviation of 2.9 (n=39), decay corrected to June/2002, with a range of 0.03 to 1.7 Bq kg(-1), were obtained. Based on the (137)Cs mean concentration in fish as well as in seawater, a transfer factor of 1 x 10(2) was calculated, which is quite in agreement with the recommended value found in the Safety Report Serie 19.

Evaluation of the Siltation of River Taquari, Pantanal, Brazil, through 210Pb Geochronology of Floodplain Lake Sediments

This work presents the 210Pb geochronology of seven bottom sediment cores, collected in three floodplain lakes located in the area of the middle Taquari River, Pantanal, Brazil. In five of them, a significant increase in the sediment mass deposition rate was observed, reflecting an increase of the sediment input to the Pantanal. Additionally, in order to validate the 210Pb results, the mercury content was determined for two sediment cores, showing that despite a constant concentration, the flux of Hg has increased due to an increase in the mass sedimentation rate. This increase can be attributed to the expansion of agricultural activity in the upper Taquari River during the last 25 years.

The areas of high natural radioactivity and TENORM wastes

Abstract There are many areas of high natural radioactivity (HINAR) throughout the world. To mention a few, the monazite-bearing sands in the Kerala coast in India and in the coastal regions of the states Espirito Santo and Rio de Janeiro in Brazil; the mineralized volcanic intrusives in the Brazilian states of Minas Gerais and Goias; the hot springs in Ramsar, Iran; the primitive, granitic, schistous and sandstone areas of France; and selected areas in Zaire. Some HINAR areas are such that there are sources of economically feasible ores geologically associated with naturally occurring radioactive materials (NORM). In Brazil, the main technologically enhanced naturally occurring radioactive materials (TENORM) waste-producing ores are the rare earth-rich monazite sands; phosphate rocks; and gold, lead, silver, copper, tin, tantalum and niobium associated with uranium and/or thorium. Some of these orebodies are in HINAR areas which were never investigated; while, on the other hand, some others are in HINAR areas which have been extensively studied. This work discusses the advantage of using the exposure baseline in the Brazilian HINAR areas, whenever available, for the interpretation of exposures to TENORM resulting from the extraction and/or industrial processing of orebodies bearing NORM.

Application of inductively coupled plasma quadrupole mass spectrometry for the determination of monazite ages by lead isotope ratios

In order to evaluate the applicability of inductively coupled plasma quadrupole mass spectrometry to the determination of Pb/Pb, U/Pb and Th/Pb ages of monazite, studies were carried out initially applying lead atom ratio reference standards (NIST SRM 981 and 982). Further, the optimized methodology was applied to monazite sands from three different sites, Sugar Loaf Hill (Rio de Janeiro city), Buena (Rio de Janeiro state) and Black Sands Beach (Guarapari, Espirito Santo state); the obtained mean ages, (581 ± 21)Myears, (552 ± 32)Myears and (535 ± 3)Myears, respectively, are in agreement with the literature values for zircon and monazite samples from the same sites. Single grain Th/Pb ages were also determined for the monazite sample from Black Sands beach, nine grains were analyzed and the mean value, (530 ± 26)Myears, is in agreement with the value obtained with bulk samples. Finally, the method was applied to a thorianite sample from Amapa state and the observed Th-Pb, U-Pb and Pb-Pb ages obtained were (2.15 ± 0.05)Gyears, (2.03 ± 0.01)Gyears anda (2.044 ± 0.006)Gyears respectively, with a mean value of (2.08 ± 0.07)Gyears. This value is coherent with the (2.08 ± 0.02)Gyears age of the Bacuri complex, Amapa, reported in the literature.