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172 Nuclear Science and Technology | Progress Report

analysis technique (INAA) and toxic metals ment pollutants in two arboreal species, Sibi-
(Cd, Hg, Ni and Pb) by Atomic Absorption Spec- piruna (Poincianella pluviosa) and Tipuana
trometry (CV AAS and GF AAS). In order to (Tipuana tipu, Kuntze) abundant and domi-
verify if they can be used as a biomonitor for nant in urban areas of São Paulo city, using
metal contamination in the regions studied the instrumental neutron activation analysis
and others, the concentration results for the (INAA) and graphite furnace atomic absorp-
toxic metals and trace elements in the sea tion spectrometry (GF AAS) methods.
urchin species tissues are being investigated.
This project also aims to contribute with values Results obtained indicated that element con-
for micro and macronutrient concentrations centrations in the barks depend on the tree
for these organisms, due to the lack of infor- species. Higher element concentrations ob-
mation in the literature. (Partnership: Instituto tained for Tipuana rather than those for Sibi-
de Ciências Biomédicas da Universidade de São piruna can be attributed to the characteristics
Paulo; Universidade Estadual Paulista Júlio de of the bark surface. The Tipuana bark surface
Mesquita Filho, Campus do Litoral Paulista; is porous, roughened and fissured while Sibi-
Financial support: CNPq - PROANTAR) piruna presents barks in squamous form. Fig
21 shows trunk bark images of the Sibipiruna
Biomonitoring of chemical element and Tipuana tree species. The entrapment
pollutants in Tree barks and accumulation of elements in tree barks
depends on structure porosity.
Investigations on aerial pollution and its ef-
fects on public health have become import-
ant in programs related to the reduction of
pollutant levels in many cities of the world.
São Paulo city is no exception. The use of a
biomonitor to evaluate pollution levels should
be considered as an additional support to con-
ventional instrumentation currently in use by
the governmental agency, the Environmental
Company of São Paulo State (CETESB) due to
the extension of São Paulo city, as well as, to
serious pollution problems. Thus, in order to Fig 21. Bark surfaces of the Sibipiruna and Tipuana trunks..
develop a biomonitoring program, it is very
relevant to choose a suitable monitor. Besides, to obtain a representative sample,
it is relevant to collect barks around the
The applicability of tree barks for air moni- trunk as well as to take the same thickness
toring purposes is increasing due to its sim- of outer layer for the analysis since there are
plicity of sampling without causing damage differences between outer and inner layer
to the tree, easier sample treatment and tree element concentrations. Different layers of
species identification when compared with tree bark indicated that most of the element
other species such as lichens or mosses that concentrations in the outer layer are higher
often require a specialist in taxonomy. than those found in the inner layer (Fig 22).
Results of bark analyses collected in differ-
This study focused on the evaluation of ele- ent sampling sites of São Paulo Metropolitan

Instituto de Pesquisas Energéticas e Nucleares