Evaluation of the Geochemical Behavior and Environmental Risk of Metals in an Area Impacted by Industrial Waste in Queimados (RJ)

Abstract

Areas contaminated with metals may pose a serious risk to public health and the environment. At the end of the 1980s, an installment of temporary storage of hazardous industrial waste was available in the area of the Centro Tecnológico de Residuos (CENTRES), in the municipality of Queimados, state of Rio de Janeiro. Inadequate management of these wastes has had a major environmental impact on the soil in the region. So, in 2009, soils of this company were sampled to be evaluated the mobility, toxicity, bioavailability and environmental risk of Cd, Cr, Cu, Ni, Pb and Zn, sequentially extracting for the geochemistry fractionation (BCR) and metals determinated by ICP OES. The sum of all the geochemical fractions presented a sample P1 is severely contaminated by Zn, and which as P5 and P5.1 samples are contaminated by Cu, Ni, Pb and Zn, that a sample P5.2 is contaminated by Ni, Pb and Zn and that the sample P6 has Ni concentrations exceed the value of industrial research recommended by the Brazilian legislation. Generally, Cd, Ni and Zn are shown as the most mobile metals, due to the enrichment of their concentrations in the soluble and exchangeable fraction of the soil (F1). Pb was only found to be highly soluble and exchangeable in soil samples that were severely contaminated with this metal. On the other hand, Cu and Cr showed to be less mobile, preferring to be adsorbed to the oxidizable fraction of the soil (F3) or to the residue (R), which contains a silica matrix and high crystalline oxyhydroxides. Finally, the risk assessment code (RAC) proved to be a limited measure in overestimating the environmental risk of Cd and Ni and underestimating that of Cu. Keywords: Soil pollution; BCR and environmental risk assessment (RAC). ResumoÁreas contaminadas por metais podem configurar sério risco à saúde pública e ao meio ambiente. No final da década de 1980 foi instalado um pátio de estocagem provisória de resíduos industriais perigosos na área da empresa Centro Tecnológico de Resíduos (CENTRES), no município de Queimados, RJ. A gestão inadequada destes resíduos proporcionou um grande impacto ambiental ao solo da região. Então, em 2009 foram amostrados solos desta empresa para que fossem avaliadas a mobilidade, toxicidade, biodisponibilidade e risco ambiental de Cd, Cr, Cu, Ni, Pb e Zn utilizando extração sequencial para o fracionamento geoquímico (BCR), determinando-se as concentrações destes metais por ICP OES. A soma de todas as frações geoquímicas mostraram que a amostra P1 é severamente contaminada por Zn, que as amostras P5 e P5.1 são contaminadas por Cu, Ni, Pb e Zn, que a amostra P5.2 é contaminada por Ni, Pb e Zn e que a amostra P6 possui concentrações de Ni que ultrapassam o valor de investigação industrial preconizado pela legislação brasileira. Geralmente, o Cd, o Ni e o Zn se mostraram como os metais mais móveis, devido ao enriquecimento das suas concentrações na fração solúvel e trocável do solo (F1). O Pb só se mostrou altamente solúvel e trocável em amostras de solos que foram severamente cont...