RESUMO
Rare earth elements (REE) have unique chemical properties, which allow their use as geochemical tracers. In this context, the present study aims to assess the role of Funil Reservoir on REE biogeochemical behavior. We collected water samples upstream of the reservoir (P-01) in the city of Queluz, inside the reservoir (P-02), and downstream of Funil Reservoir (P-03) in the city of Itatiaia, RJ. In the field, physicochemical parameters were measured using a probe (pH, temperature, electrical conductivity, and dissolved oxygen). In the laboratory, water samples were filtered (0.45 µm) and properly packed until chemical analysis. Chlorophyll a concentrations were determined by a spectrophotometric method and suspended particulate matter (SPM) by a gravimetric method. Ionic concentrations were determined by ion chromatography technique and REE concentrations were determined by ICP-MS. Chlorophyll a concentrations were higher in Funil Reservoir. Ionic concentrations in Queluz (P-01) suggest anthropic contamination. The sum of REE in the dissolved fraction ranged from 2.12 to 12.22 µg L-1. A positive anomaly of La in Queluz indicates anthropic contamination. The observed patterns indicate that Funil Reservoir acts as a biogeochemical barrier, modifying the fluvial transport of REE. Nonetheless, another factor that probably influences REE behavior is the algal bloom that occurs in reservoirs during the rainy season. The seasonal behavior of algae can influence REE biogeochemistry through the incorporation and release of trace metals.
Assuntos
Metais Terras Raras , Poluentes Químicos da Água , Clorofila A/análise , Brasil , Monitoramento Ambiental , Metais Terras Raras/análise , Água/análise , Poluentes Químicos da Água/análiseRESUMO
Industrial electron accelerators are used by eight installations in Brazil, with a total of 14 machines generating electron beams. These facilities are classified into categories I or II, according to the International Atomic Energy Agency (IAEA) system. In category I are included the facilities with an integrally shielded unit with interlocks, where human access during operation is not physically possible owing to the configuration of the shielding. In category II are included the facilities with a unit housed in a shielded room that is kept inaccessible during operation by an entry control system. Of the 14 accelerators operational in Brazil, 11 belong to category I and three to category II. In the present work a methodology for the assessment of the radiological safety of these accelerator facilities was developed and applied, mainly on the basis of specific recommendations from the IAEA. The main safety items were evaluated at those eight installations. According to the results obtained here, no inadequacies were observed at the three installations in category II, from the radiological safety and radioprotection points of view. Nevertheless, two out of the five installations in category I showed several deficiencies. Most of these inadequacies have been corrected during this work, and the rest are in the course of being corrected.