Brazilian Station Research Articles

Vertical distribution of macrobenthic infauna from the shallow sublittoral zone of Admiralty Bay, King George Island, Antarctica

A 0.0625 m2 mini-box corer (MBC) was used to study the vertical distribution of macrobenthos in the shallow sublittoral zone of Admiralty Bay, during the 2003/2004 summer, near the Brazilian Station Comandante Ferraz, and the Peruvian Station Machu Picchu. Sediment samples were taken from 20, 30 and 60 m, and stratified for particle-size, total organic matter (TOM) and faunal composition analysis. The most abundant taxa were Polychaeta, Oligochaeta, Amphipoda, Cumacea, Bivalvia and Gastropoda. In general, macrofauna were concentrated in the 0–4 cm layer (64% of total organisms). Correlations between sediment characteristics and faunal densities have not completely explained neither the aggregation of organisms at the surface sediment layers nor the differences in faunal composition between locations at 20 m depth. Analysis of parameters such as organic carbon, heavy metals, interstitial water, and species composition should contribute to a better understanding of the diversity patterns found in this study.

An update of the probabilistic safety assessment of the Radiation Monitor Calibration Laboratory of a Brazilian nuclear power station

In 2001, a probabilistic safety assessment of the Radiation Monitor Calibration Laboratory of a Brazilian nuclear power station was performed to estimate its radiological risk. Owing to the lack of data, many conservative assumptions were considered. The purpose of this paper is to obtain the updated laboratory radiological risk. A human reliability analysis of the procedure for calibrating the monitors was performed by applying the Technique for Human Error Rate Prediction (THERP) methodology. For facing the lack of failure data, the Bayesian approach was used for the calculation of the irradiator failure probability. The exponential distribution was used to model the failure times of the electronic dosimeters. The radiological risk was obtained through an event tree, in which all relevant scenarios were considered. Although more accident scenarios were considered in the analysis, like external events, the approach was by no means conservative, and a radiological risk about one order of magnitude smaller was obtained.

O interrogatório policial no Brasil: a fala institucional permeada por marcas de conversa espontânea

The article discusses how police interrogations in a Brazilian police station are constituted and what characteristics make them different from police interrogations investigated in other cultural contexts. We take as bases for comparison studies of police interrogation conducted by Shuy (1998), in the USA, by Komter (2003), in the Netherlands, and by Heydon (2005), in Australia. Whereas the police interrogations in Australia, USA and the Netherlands are similar in the way they are conducted (avoidance of expressions of sympathy, affiliation or disaffiliation with the deponents, use of technical jargon throughout the interrogation, among others), the Brazilian police interrogations in the context investigated diverge from all of those in several aspects. The main phenomena responsible for such dissonance are: (1) use of irony, (2) creation of hypotheses without making use of metalanguage, and (3) use of evaluations about situations concerning the crime, topics mentioned by the deponent, and the deponent himself/ herself. The interrogations conducted by the Brazilian police officers are also permeated by laughter, less caution with regards to maintaining a position of neutrality, affiliation and disaffiliation by the officers, options that seem to give characteristics of spontaneous conversations to those interactions. Key words: police interrogation, institutional interaction, spontaneous conversation.

Aliphatic and polycyclic aromatic hydrocarbons in surface sediments in Admiralty Bay, King George Island, Antarctica

Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) concentrations were measured in marine surface sediments around the Brazilian station in Admiralty Bay, during the summers of 1997/98 and 1999/2000 using GC-FID and GC-MS. Total aliphatic hydrocarbons ranged from 0.15 to 13.28 μg·g−1 (dry weight) while n-alkanes varied between 0.10 and 9.63 μg·g−1. The highest concentrations were obtained at the sewage outfall, with decreasing levels away from the outfall. The distribution of n-alkanes showed significant quantities of long chain n-alkanes (n-C22 to n-C34) at sites near the Brazilian station that may be attributed to the station activities. A short chain n-alkanes sequence (n-C12 to n-C21) associated with diesel fuel arctic (DFA) was present in all the samples. Total PAHs varied from 9.45 to 270.5 ng·g−1. The higher PAHs level and the presence of an unresolved complex mixture only in sediment from the sewage outfall is an indication of oil contamination at this location. A slight increase in PAHs near the Brazilian station since 1993 may be attributed to an increase in the number of staff over recent years. In general, the concentration of AHs and PAHs was similar to that found in other Antarctic areas.

Shear-wave velocity in the south-eastern Brazilian continental shelf

SUMMARY The crustal structure of the south-eastern Brazilian continental shelf has been investigated through the dispersion curves of seismic surface waves obtained at Brazilian seismological station RDJ. A set of eight continental-shelf models has been tried, to obtain the best shear-wave velocity structure. The inversion results suggest a sedimentary structure divided into two layers with shear-wave velocities of 1.36 f 0.10 km s-' and 1.58 f 0.10 km s-', respectively. This is in agreement with preliminary results found by the Brazilian Petroleum Company Petrobras using seismic data in the area (0. R. S6 & L. P. A. Gamboa, private communication, 1994). The intermediate crustal layer has a shear-wave velocity (3.26 f 0.10 km s-l) typical of basement. An anomalous shear-wave velocity of 3.98 f 0.10 km s-' has been determined for the lower crust. This suggests the existence of a transitional layer between lower crust and upper mantle, similar to that observed in both Mediterranean and Canadian passive continental margins. It was not possible to define precisely the crust-mantle transition, but an analysis of the inversion results has shown that the Moho boundary is at around 40 f 5 km depth.

Trace element determination in aerosols from the Antarctic Peninsula by neutron activation analysis

The knowledge of the composition of atmospheric aerosols in remote areas, like the Antarctic Peninsula is of great importance for the study of long-range transport of atmospheric contaminants and also from the climatological point of view. Instrumental neutron activation analysis was applied in the present work to determine the elements Al, V, Mn, Na, Cl, Ca, Au, Br, Sb, Sc, Fe, Zn, K, Th and La in aerosol samples collected in the Brazilian Antarctic Station “Comandante Ferraz” (62° S, 58° W) located on King George Island in the Antarctic Peninsula. The sources of the aerosols were investigated by means of Enrichment Factors and Principal Factor Analysis. Both methods yielded similar results. Sea and soil were identified as the major sources of aerosols, in the samples collected at the Brazilian Station.

Radon-222 time series measurements in the Antarctic peninsula (1986—1987)

Continuous measurements of radon-222 were conducted at Comandante Ferraz (62°S, 58°W), a Brazilian station in the Antarctic Peninsula, during the winters of 1986 and 1987. The average concentration of radon-222 was 0.026 ± 0.018 Bq m -3 in 1986 and 0.014 ± 0.008 Bq m -3 in 1987. The higher average of 1986 was attributed to the stronger winds in 1986 compared to those observed in 1987. Large surges of radon reaching up to 0.13 Bq m -3 were affected by local radon emissions due to soil defrosting. Bare soils and atmospheric stability also favored local contributions. Radon peaks attributed uniquely to air mass trajectories passing over the South American continent occurred during the 2 years of monitoring. Periodicities of 25 to 30 days in the time series of radon corroborate with previous results obtained by other authors in east Antarctica. DOI: 10.1034/j.1600-0889.1990.00006.x