of a monitoring plan, selection of sampling sites, establishment of frequency campaigns, ... In parallel, was used the c
Use of LUMEX and the conventional method to measure mercury concentration in ambient air at Caraguatatuba, São Paulo, Brazil. Paper 538 Luciana N Loureiro, Maria Cecilia G P Massa Maria Luiza B Tristão Ricardo Gutierres Petróleo Brasileiro S.A –Petrobras Centro de Pesquisas Leopoldo de Américo Miguez de Melo –CENPES Gerência de Avaliação e Monitoramento Ambiental –AMA Av. Horácio de Macedo, 950 –Ilha do Fundão –Rio de Janeiro –RJ - Brasil - CEP: 21941-915
[email protected] Luiz Drude de Lacerda Marcelo Dominguez de Almeida Laboratório de Estudos da Baixa Atmosfera Laboratório de Biogeoquímica Costeira Insituto de Ciências do Mar, Universidade Federal do Ceará Av. Abolição 3207, Fortaleza –CE - Brasil - CEP: 60.165-081
ABSTRACT The mercury (Hg) is a relatively abundant element in nature. Among the different chemical forms of mercury, the specie of major distribution is the elemental form, Hg0 (in gas phase), predominant in the atmosphere. The present paper summarizes the development of a methodology to effectively measure elemental mercury concentration in ambient air, applied in Caraguatatuba, São Paulo, Brazil. Within the development of this methodology were included many key aspects such as: preparation of a monitoring plan, selection of sampling sites, establishment of frequency campaigns, definition of sampling time and the location of automatic analyser. The developed methodology use an automatic analyser LUMEX RA915 +, operating at atomic absorption spectrometry that measures the concentrations of Hg0 in a certain period of time. In parallel, was used the conventional techniques of monitoring Hg 0 concentration, the manual gold trap method, for intercomparing of the methods. The main advantage of using an automatic analyser is avoiding subsequent analysis in the laboratory. The average concentration obtained during the campaigns was similar to the background air throughout uncontaminated areas. For all the selected sites in Caraguatatuba, the seasonal pattern of gaseous mercury was indicative of southern hemispherical background. The environmental behavior of Hg0, while exhibiting clear distinctions over diurnal and/or seasonal scales, was found to experience sharp changes for a very short time period, usually less than a few tens of seconds. The aplication of this methodology using an automatic analyser for monitoring Hg0concentration has presenting a potential for using in evaluations to understand the atmospheric behavior of Hg0 in several areas with reduction of time and costs.
1
INTRODUCTION Mercury (Hg) is a natural element of ubiquitous distribution in the planet (geoesphere, hydrosphere and biosphere) occurring in varying concentrations. The atmospheric mercury exists in the following forms: gaseous elemental mercury (Hg0, 90 to 99%), mercury bound to particulate matter (Hgp,
