Characterization, fractionation and mobility of trace elements in surface sediments of the Jequiezinho River, Bahia, Brazil.

Darci S Silva,Marcos A Bezerra,Rosane M Aguiar,Uilliam M.F.M Cerqueira,Paulo Luis S Carneiro

doi:10.1590/0001-3765202020190558

Darci S Silva, Marcos A Bezerra + Show 3 more

Open Access

https://doi.org/10.1590/0001-3765202020190558

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Abstract

The Jequiezinho River is a temporary river. In the urban stretch it is impacted, with perennial flow coming from domestic sewage and rainwater. This study evaluated the geochemical distribution and potential mobility of some metals (Pb, Co, Ca, Cr, Mg, Cu, Fe, Mn, Ni and Zn) in sediments of the Jequiezinho River. Sediment samples were collected at ten different sites along the river. The silt/clay fraction was submitted to acid digestion and sequential extraction with analysis by FAAS. The results indicated that, in the more densely populated region, there was an increase in concentrations of Cr, Ni, Cu, Co, Pb, and Zn. The contents found were compared with the guideline values of TEL (Threshold Effect Levels) and PEL (Probable Effect Levels), not exceeding the maximum reference limits. The results indicated that Ca, Mg, Mn and Fe presented greater susceptibility to mobility and bioavailability suggesting the geochemical origin responsible for these high concentrations. The multivariate analysis showed that Cr, Ni, Cu, Co, Pb, and Zn presented a similar behavior, especially in locations with higher population density and the discharge of non-discriminated effluents, reflecting the anthropogenic contributions as responsible for the concentration increase.

Highlights

Sediments are the layers of finely granulated mineral and organic particles that are in contact with the lower parts of natural water bodies, such as lakes, rivers and oceans (Baird & Cann 2011)
Not all the elements that comprise the sediment are available for analysis, the results obtained are sufficient to quantify the metals in the sediment, and this method is widely used in studies on chemical composition in environmental matrices
Quantification and evaluation of the behavior of metals in the Jequiezinho River The elements Fe, Mg and Ca are present in the sediments at the highest concentrations, while the other elements had lower

Summary

Introduction

Sediments are the layers of finely granulated mineral and organic particles that are in contact with the lower parts of natural water bodies, such as lakes, rivers and oceans (Baird & Cann 2011). Sediments can accumulate large amounts of chemical compounds such as metals, pesticides, polycyclic aromatic hydrocarbons (PAHs) and can be transferred to the living organisms in contact with them. Due to this fact, sediments have been widely used to monitor and track possible sources of environmental contamination, functioning as efficient environmental indicators (Soares et al 1999, Duodu et al 2016, Unda-Calvo et al 2019). Besides being considered water pollutants and food contaminants when in high concentrations, metals can be transported by air, either as gases or as adsorbed species The increased availability of these elements in the environment, where the concentrations exceed the tolerable limit, lead to serious environmental problems (Silva 2006, Vareda et al 2019).

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