Heavy Metals in an Important Section of the SÃÂ£o Francisco River (Northeast Brazil): Distribution Profile, Accumulation Mechanisms, and Risks of Dissemination through the Food ChainPereira MDG1*, Souza CLM2, Sachdev RDL1, Santos AVD1, Pinto PADC2, Souza LA1, Ribeiro JN3, Oliveira JPD3, Guimarães MCC3 and Ribeiro AVFN4
- Corresponding Author:
- Madson de Godoi Pereira
State University of Bahia
Department of Exact and Earth Sciences
R Silveira Martins, 2555, 41.150-000, Salvador-BA, Brazil
E-mail: [email protected]
Received Date: June 19, 2017; Accepted Date: June 24, 2017; Published Date: June 30, 2017
Citation: Pereira MDG, Souza CLM, Sachdev RDL, Santos AVD, Pinto PADC, et al. (2017) Heavy Metals in an Important Section of the São Francisco River (Northeast Brazil): Distribution Profile, Accumulation Mechanisms, and Risks of Dissemination through the Food Chain. J Pollut Eff Cont 5:193. doi: 10.4176/2375-4397.1000193
Copyright: © 2017 Pereira MDG,et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Background: This work assessed the distribution of Cd, Cr, Cu, Mn, Ni, Pb, and Zn in an important Brazilian fluvial section, which has never been evaluated before this study
Procedures: Along six samplings, total and bioavailable concentrations of these metals were quantified in water and sediments, respectively, by atomic spectrometry. Bioavailable metal concentrations were extracted from sediments by 0.1 molL-1 HCl, while total metal concentrations were released in water after acidic decomposition with 14 molL-1 HNO3. Sediments were submitted to analyses of X-ray diffractometry, thermogravimetry, infrared spectrophotometry, electronic scanning microscopy, granulometry, and density. Subsequently, adsorption tests were performed with those elements that tend to exist as cations in river water (Cd2+, Cu2+, Ni2+, Pb2+, and Zn2+).
Results: Water pH (6.9 to 8.3) favored precipitation of Cr and Mn, explaining their undetectable concentrations in water. Although cadmium, copper, lead, nickel, and zinc are stabilized as cations at water pH and chemical oxygen demand (<0.5 mgL-1), total concentrations of these metals in water were undetectable. Sediments presented prevalence of quartz, sandy granulometry, maximum density of 2.8 gcm-3, and remarkable bioavailable concentrations of Cr (up to 778.4 ± 37.4 mg kg-1) and Mn (up to 230.9 ± 6.2 mg kg-1, which can be readily assimilated by benthic organisms. Bioavailable concentrations of Cd, Cu, Ni, Pb, and Zn in sediments were considerable small (≤ 43.4 ± 2.5 mgkg-1). Although sediments are limited for adsorbing Cd2+, Cu2+, Ni2+, Pb2+, and Zn2+ (≤ 1.49 mgg-1), these cations are adsorbed with low reversibility, being progressively accumulated and disseminated through the food chain over a long period of time.
Conclusions: This work improved the knowledge about the distribution of heavy metals in fluvial environments, as well as evaluated the risks of an eventual contamination of humans.