Valores de referência de qualidade para metais pesados em solos no Estado do Espírito Santo

• Autor(a) principal: Paye, Henrique de Sá
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5414
• topic: Solos; Análise; Qualidade; Metais pesados; Soils; Analysis; Quality; Heavy metals; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

Balanced and sustainable development requires efficient control of the environmental effects of the productive process. For that reason, environmental agencies demand indicators capable of referencing and assessing the environmental impacts caused by anthropogenic activities. In that way, it is clear the necessity of establishing of guiding values to identify polluted or contaminated areas and, concomitantly, to assess the potential risks to the environment and to the human health. The knowledge about natural concentrations of certain substance is the easier and more direct method for the establishment of those guiding values. At the same time, the adoption of references quality values (RQVs) figures as an excellent tool to identify contaminated areas, provinding a quantitative orientation in studies which deal with risk assessment and issues regarding the deposition of waste in soil. For that purpose the present study comprised the geochemical characterization of 56 representative soil samples collected at Riacho, Reis Magos, and Santa Maria da Vitória drainage basins in Espirito Santo State. In addition, it aimed to obtain the natural concentrations of heavy metals and to investigate the main factors involved in their distribution in soils. Based on these information, references quality values (RQVs) were established through univariate and multivariate analyses. The total content of As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn were determined by inductively coupled plasma optical emission spectrometer (ICP OES), after microwave assisted acid digestion of soil samples, according to SW-846 3052 of the Environmental Protection Agency (USEPA). For the majority of the heavy metals, the average content were lower than those reported in the international references. Cadmium content were lower than the detection limit (DL) for all samples. By Pearson s correlations and principal component analyses, it was possible to select the most suitable soil attributes (e.g. silt+clay, sand, and carbon organic) which correlate to the heavy metals content and verify the importance of those variables in the results. The cluster hierarchical analysis (CHA) allowed to group formations which revealed that relief (geomorphology) and geology explained mostly the distribution of heavy metals in soils from Espírito Santo state. Discriminant analysis (DA) allowed to assess the degree of certainty in the distribution of the samples among the groups, and to place new samples in the groups already formed, according to the classification functions. The percentile 75 and 90 of the frequency distribution of the analytical results, obtained from the group of 56 soil samples, were used to estimate the RQVs or the background content. Those estimated values were lower than or similar to those ones reported to São Paulo state s and to the Brazilian s soils. Thus, the RQVs for the Espírito Santo s soils, in mg kg-1, can be seen as follow: As (< 12.83; 14.28), Cd ( < 0.13), Co (10.21; 14.56), Cr (54.13; 68.81), Cu (5.91; 10.78), Mn (137.80; 253.01), Mo (1.74; 3.36), Ni (9.17; 17.22), Pb (< 4.54; 8.92), Ti (8775.97; 10188.89), V (109.96; 129.35) and Zn (29.87; 49.32). Adoption of RQVs obtained for group of soils is advantageous due to the representation of the anomalous situations. Therefore, it suggests that the 75 and 90 percentiles would be considered as background fluctuations or RQVs range for heavy metals in soils from Riacho, Reis Magos and Santa Maria da Vitória basins.