Atmospheric pollutant monitoring by neutron activation analysis of epiphytic lichens
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2006
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INTERNATIONAL WORKSHOP ON BIOMONITORING OF ATMOSPHERIC POLLUTION, 4th
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The epiphytic lichen Canoparmelia texana was used to monitor atmospheric pollution in the São Paulo metropolitan area, SP, Brazil and to obtain distribution maps of element concentrations. From July
2003 to February 2004, lichens were collected from the bark of trees in 23 sites all near automatic
monitoring stations belonging to the Environmental Protection Agency of the State of São Paulo and
analyzed by instrumental neutron activation analysis. For the analyses, lichen samples were first
cleaned by examining them under a stereomicroscopy to emove foreign materials, and then
immersed in purified water for about 3-5 minutes. Then the samples were freeze-dried and ground to
a powder using a vibratory micro mill. Samples and synthetic element standards were irradiated for
long and short periods at the IEA-R1 nuclear research reactor under thermal neutron flux of about 5
x1012n cm-2s-1 . The induced gamma activities of the irradiated samples and standards were measured
using a HGe detector coupled to a gamma ray spectrometer. Concentrations of the elements As, Ba,
Br, Cl, Co, Cr, Cs, Fe, K, La, Mn, Mo, Na, Rb, Sb, Sc, Se, U and Zn were determined in the lichens and
these results were submitted for sampling sites classification by cluster analysis. The cluster analysis
confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In
the distribution maps of element concentrations, higher concentrations of elements were observed in
the vicinity of industries. High concentrations of elements found in lichens from the Santo André
sites may be associated to the emissions from industries and a petrochemical complex located in this
region. The highest concentration of Co found in lichens from São Miguel Paulista site is probably
due to the emission from a metallurgical processing plant that produces this element. The accuracy
and the precision of the results were evaluated by the analyses of certified reference materials IAEA
336 Lichen and INCT-MPH-2 Mixed Polish Herbs. Results obtained for these certified reference
materials showed a good precision and a good agreement with the certified values for most elements.
Como referenciar
FUGA, ALESSANDRA; SAIKI, MITIKO; MARCELLI, MARCELO P.; SALDIVA, PAULO H.N. Atmospheric pollutant monitoring by neutron activation analysis of epiphytic lichens. In: INTERNATIONAL WORKSHOP ON BIOMONITORING OF ATMOSPHERIC POLLUTION, 4th, Sept. 17-21, 2006, Agios Nikolaos, Greece. Abstracts... Disponível em: http://repositorio.ipen.br/handle/123456789/19948. Acesso em: 26 Mar 2026.
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