RESUMO
The ornamental rock exploration and coating industry has led to significant environmental impacts due to the inadequate manner in which these residues are released into the environment. This impact may be reduced by using these residues for soil enrichment, as they contain high levels of inorganic nutrients. However, some elements may be potential contaminants, thus requiring a thorough previous research before employing these substances in agriculture. In this context, this study aims to determine potentially toxic elements present in rock dust residues, As, Cd, Cr, Cu, Pb, and V, through Inductively Coupled Plasma Optical Emission Spectroscopy (ICP OES) after wet decomposition. Cd concentrations in residual rock dust waste surpassed the maximum limit established by the Brazilian Ministry of Agriculture, Livestock and Supply stipulated in normative instruction No. 5/2016 for remineralizers and substrates for plants intended for agriculture. In addition, the official digestion method adopted by the Brazilian Agricultural Research Corporation Embrapa (used for soil analysis) was used for a rock dust waste analysis and compared to two different block digester-based procedures. Accuracy was confirmed by using the Certified Reference Material (CRM) NIST SRM 1646a (Estuarine Sediments) and addition/recovery tests. The limits of detection for the aforementioned elements, after aqua-regia-induced digestion, were of 0.07 mg kg-1 for As, 0.06 mg kg-1 for Cd, 0.01 mg kg-1 for Cr, 0.2 mg kg-1 for Cu, 0.03 mg kg-1 for Pb, and 0.09 mg kg-1 for V.
Assuntos
Poeira , Fertilizantes , Brasil , Monitoramento Ambiental , SoloRESUMO
The Zumbi dos Palmares land reform settlement lacks modern facilities for water and sewage treatment. Local farmers often use shallow wells as alternative source of water supply, because the water table is reasonably high in the region. This work presents a multivariate analysis assessment of physicochemical and bacteriological parameters and pesticide residues in water samples collected from these shallow wells. The physicochemical parameters analyzed were: conductivity, pH, DOC (dissolved organic carbon), nitrate, turbidity, and bacteriological analysis measuring total and fecal coliforms. The results show non-compliance with Brazilian legal standards in most samples where low pH values were found, characterizing the presence of acidic waters. Another example of non-compliance is the presence of total and fecal coliforms in for drinking water in most of the samples and, in some cases, very high values (2,400 CFU). Some wells showed high conductivity values, probably associated with a history of oceanic intrusion. Analyses determining the contamination by pesticides show the presence of ametrine, atrazine, methyl parathion, carbaryl and hexazinone. The concentration for these compounds ranged from 0.14 to 1.17 µg/L. Ordinance No 2914/2011 from the Brazilian Ministry of Health establishes the acceptable limits for atrazine and methyl parathion as 9 µg L-1 and 2 µg L-1. None of these exceeded the allowable Brazilian and European limits. However, for the other two pesticides, the European Legislation (Council Directive) recommends the maximum allowable concentration of 0.1 µg L-1 and, 0.5 µg L-1 for total pesticides. Our samples that were above the quantifiable limit of 50 ng L-1, were also above the European limit values. Our results therefore suggest that water gathered from shallow wells at the Zumbi dos Palmares settlement is not proper for consumption without proper disinfection treatments.