The need for solutions to minimize the negative environmental impacts of anthropogenic activities Fhas increased. Sewage sludge is composed of predominantly organic matter and can be used to improve soil characteristics, such as fertility. Therefore, its application in agriculture is an adequate alternative for its final disposal. However, there is a lack of information on its long-term effects on soil changes in tropical areas. Thus, the objectives of this study were to determine (i) the effect of sewage sludge application on heavy metal build-up in soil and maize grains and leaves, and (ii) the effects of soil amendment with sewage sludge on the chemical properties of a Brazilian oxisol. Besides the increasing levels of Zn, Cu, Ni, and Cr, amending soil with sewage sludge also alters the distribution of these metals by increasing the mobile Phases, which correlated significantly with the increase in metal extraction with two single extractants, Mehlich 1 and DTPA (Diethylene triamine pentaacetic acid). The levels of Fe, Mn, Zn, and Cu in maize grains and leaves increased with the type and rate of sewage sludge application. Nevertheless, metal build-up in soil and plants was within the allowed limits. Significant differences were also found in soil characteristics like humic fractionation with the applied sewage doses. The data obtained does not indicate any expressive drawbacks in the use of sewage sludge as a soil amendment, as the heavy metal concentrations observed are unlikely to cause any environmental or health problems, even overestimated loadings, and are in accordance with the Brazilian regulations on farming land biosolid disposal.

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Recebido em 21/9/07; aceito em 7/3/08; publicado na web em 26/9/08 WASTE LABORATORY MANAGEMENT UNDER THE VIEWPOINT OF UNDERGRADUATE STUDENTS OF A CHEMISTRY COURSE AND RELATED AREAS. This work presents the students´ profile before and after working in the course "Laboratory Chemical Waste Treatment" in the last ten years. The structure of the course is also described. Although students have shown an increasing previous experience on waste management, many fundamental aspects are missing, especially knowledge on the directives focusing environmental aspects. Visits to industrial plants are also essential to better understand the impact of wastes in environment. Most students nowadays consider waste management as an essential part of their professional formation. A good waste management program must consider several topics of extreme relevance.Keywords: waste management; laboratory waste; chemistry teaching. introduçãoNo 1º semestre de 1998, foi instituída uma disciplina eletiva na grade curricular do curso de química, oferecido pelo Instituto de Química da Universidade Federal do Rio de Janeiro (IQ/UFRJ), Tratamento de Resíduos Químicos de Laboratório. Seus pré-requisitos são as disciplinas Análise Quantitativa I e Análise Quantitativa Experimental I, ambas oferecidas no 3º período do curso em questão. É importante assinalar que não há uma preocupação apenas em formar profissionais capacitados a lidar com resíduos, mas também colaborar na formação cidadã geral, inserindo essa questão em um universo muito mais amplo, envolvendo não só aspectos ambientais, mas também sócio-econômicos, políticos e tecnológicos. Por isso, acredita-se que um aluno ainda no início do curso não tem maturidade suficiente para que possa freqüentar a disciplina com o aproveitamento desejado. Com a base oferecida pelas disciplinas nas áreas de Química Orgânica, Analítica e Inorgânica dos três primeiros períodos, os alunos têm condições e são orientados a freqüentá-la a partir do 4º período.A proposta desta disciplina segue uma grande ênfase a partir da década de 90, que é a questão da gestão e do tratamento de resíduos químicos gerados em laboratórios. As experiências pioneiras no país 1-3 e os relatos dos resultados positivos obtidos, particularmente na UNICAMP 3 e na UFRGS, 1 levaram à necessidade de implantar no IQ/ UFRJ uma disciplina que estivesse em sintonia com a tendência então observada, o que também significava uma oportunidade adicional para os alunos investirem em sua formação profissional.Com carga horária prevista de 5 h semanais (75 h por semestre), e 10 vagas por turma, a disciplina tornou-se nestes últimos 10 anos uma das eletivas mais procuradas pelos alunos do Instituto, com 152 alunos atendidos em 18 turmas. estruturA dA disciPlinAA organização da disciplina é fundamentada em três tipos de atividades: aulas de laboratório, onde os alunos reconhecem a importância da segregação (separação) na fonte e têm iniciação às téc-nicas de tratamento das diversas correntes de resíduos identificadas; palestras com especialistas, ocasi...

Considering the increasing need for reliable soil carbon (C) and nitrogen (N) determinations, 19 Brazilian soil samples were selected to compare the results of two methods (a) a modified dichromate wet digestion and Kjeldahl that has been in use by Embrapa in most of Brazilian soil surveys (Embrapa's method), and (b) an automated technique based on dry combustion (PerkinElmer 2.400 Series II-CHN Mode). Considering that the last method is very much influenced by sample size, two weights were tested (10 and 100 mg). The influence of two particle sizes for both 295 ORDER REPRINTS methods (crushed and sieved to pass a 0.177-mm mesh) was also tested. A simple linear regression with the confidence limits for the intercept and slope were used to compare methods. Precision was evaluated by the coefficient of variation (C.V.). The results showed that simple crushing is inadequate for performance analysis by dry combustion mainly for small samples (10 mg), where the precision is also low (19.77% for N and 9.41% for C). The dry combustion method is significantly affected by the use of small samples (10 mg), mainly for N analysis. For finely ground samples (Ͻ0.177 mm), a comparison of the results obtained by dry combustion (100 mg weight sample) and by Embrapa's method showed a significant 1 : 1 relation. Thus the use of correction factor is not necessary.

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