Laboratory of Radioecology and Environmental Change

The Nuclear Physics Applied to the Environment

LARA uses radio and stable isotope analysis to conduct studies on various topics of environmental science, such as biophysics, geophysics, geochemistry, paleontology, archeology, and radioecology. From simultaneous applications of these innovative techniques, it is possible to charactere, for exemple, the climate change ans its impact on land-water-ecosystem quality in fragile regions across the world.

For this purpose, LARA uses four main nuclear and isotope-based techniques in an integrated way:

  1. Fallout RadioNuclides (FRN);
  2. Compound Specific Stable Isotope (CSSI);
  3. Fourier Transform Infrared Spectroscopy (FTIR) and;
  4. Accelerator Mass Spectrometry (AMS). 14C-AMS is available at LAC.

FRN technique [Cesium-137 (137Cs, T½ = 30.2 Yr), Excess Lead-210 (210Pbex, T½ = 22.2 Yr), Beryllium-7 (7Be, T½ = 53.3 days)] have proved to be the most successful tools to assess soil erosion in different time scales and determine the efficiency of soil conservation measures in controlling erosion and protecting water quality.

CSSI is an analytical method that measures the ratios of naturally occurring stable isotopes of carbon (12C, 13C) in environmental samples, allowing to identify sediment sources linked to different land cover (plants, food, grass, trees, etc.) and determine the historical causes of soil degradation. It is based on carbon specific signature of the plant fatty acids. Thus, it is crucial to identify and estimate the apportion hot spots on land degradation, and to test temperature sensitivity of soil organic matter decay and temperature sensitivity of microbiological physiology. Therefore, CSSI is crucial to identify and apportion hot spots of land degradation, and to test temperature sensitivity of soil organic matter decay in permafrost soils.

FTIR can predict a wide range of chemical and physical soil properties that are closely related to the bulk properties of soil (clay, organic matter, moisture content, cationic capacity, mineralogy).

14C-AMS is a highly sensitive analytical technique that can be used to generate temporal mathematical models of evolution of marine, terrestrial and Antarctic ecosystems. 14C dating can be used for dating the glacier variability and calculating/validating sedimentation rates. If nuclear techniques can give exact time dimension of processes, other methods can give only relative age of them.The UFF (LAC) is the first research centre of Latin America to have an electrostatic accelerator designed to 14C-AMS. The Brazilian system includes an open air deck 250 kV single stage electrostatic accelerator with magnetic and electrostatic analysers that enable isotope separation and detection.

Our staff is composed bu scientists of different backgrounds, such as physics, biology, chemestry, glaciology, soil science, geography, environmental science, water management, marine geology, paleogeography and, isotopic science.

This is because this team believes that to fully understand the functioning of the habitat of living organisms is necessary to understand it in a comprehensive and sustainable manner, not just looking at it from a single angle or sub-area of research. This includes the knowledge of the ingress, transit and, accumulation rates of stable and radio isotope in the biosphere as the environmental reconstruction of the Earth’s recent past. Thus, one needs constantly determinations of composition, concentration and absolute age of several elements present in rocks, sediments and organic materials.

LARA - Laboratório de Radioecologia e Alterações Ambientais - IF-UFF
Instituto de Física da Universidade Federal Fluminense
Av. Gal. Milton Tavares de Souza, s/nº - Campus da Praia Vermelha - 24210-346 - Niterói - RJ - Brazil
Phone number: 55-21-26295770 or 55-21-26295843 FAX: 55-21-26295887

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