Tese
Estudo de biomonitoração para urânio e tório aplicado a análise por ativação neutrônica no Centro de Desenvolvimento da Tecnologia Nuclear
Fecha
2019-07-11Autor
Rodrigo Reis de Moura
Institución
Resumen
The study of environmental conditions using biological systems to quantify elements, whether
metals, radionuclides or another type of agent (contaminant, pollutant, stressor) present in the
environment using a living organism (biomonitor), is a strategy that uses the narrow relationship
between the biomonitor and the environment studied, because the biomonitor can be part of the
environment and interact with the agents present in it. Thus, biomonitoring should be able to
quantify the stress magnitude, characterize the habitat as to the exposure degree to the stressor
or the ecological response degree to exposure. Due to their high sensitivity characteristics,
plants have been used as biomonitors in environmental impact studies and in various
environmental monitoring programs. Most of the elements uptake in the environment by plants
is through their roots. However, this uptake may also occur in contact with the atmosphere
through some edible organs or shoot (leaves and stem). In addition, plants also have the ability
to translocate and accumulate many of these elements in different parts of their anatomy. The
Nuclear Technology Development Centre (CDTN/CNEN), located in Belo Horizonte, Minas Gerais,
at the Campus of Federal University from Minas Gerais (UFMG) is an autarchy with the purpose of
research and development, teaching and provision of services whose activities involve the handling and
radioisotope production, has implemented in its organizational structure an Environmental Monitoring
Program (PMA) since 1985 – being Licensed to operate by CNEN (National Nuclear Energy
Commission) and IBAMA (Brazilian Institute of Environment and Renewable Natural Resources), LO
225/2012. Aiming at optimizing the environmental monitoring methodology developed by
PMA/CDTN, this study was proposed in three stages: the first step, verification of the methodology of
natural radioactivity analysis developed at PMA/CDTN; The second stage consisted of verifying the
absorption, translocation and accumulation capacity of plants used in PMA/CDTN in a controlled
environment. and the third stage consisted of establishing a natural biomonitor for the monitoring of the
CDTN area. Epipremnum pinatum, is an abundant plant in the area of the CDTN, was evaluated and
established, among the other species used in this study, as a biomonitor for presenting the main
characteristics expected for such function. The analyzes for obtaining the mass fractions and the activity
concentrations of both the plants and the soil hosting them were performed by the nuclear technique,
Neutron Activation Analysis (k0-Method): Step 1, it was found that soil and plant sampling
methodologies in PMA / CDTN can be optimized. Step 2, it was found that the species used in
PMA/CDTN in greenhouse studies had good results only in the study in soil with naturally U and Th
high concentrations. Step 3, it was verified that Epipremnum pinatum showed good uptake U and Th
and low translocation to shoot in relation to their high accumulation in the roots. Thorium was more
bioavailable in the outdoor study. Uranium was more bioavailable in the greenhouse study.