Geochemistry of the upper estuarine sediments of the Santos estuary: provenance and anthropogenic pollution

Bruno Calado,Colombo Tassinari

doi:10.29396/jgsb.2020.v3.n3.4

Abstract

Major and trace element geochemistry of the upper estuarine sediments of the Santos estuary has been used to characterize sediment geochemistry, classification, distribution, and possible sources of industrial pollution. The vertical sediment cores were collected on the margin of the Cubatão, Perequê, Mogi, Piaçaguera and Jurubatuba rivers, the main effluents of the Santos estuarine system. Samples of selected basement rocks (n=12), industrial waste (n=2) and one weathering profile (organic soil, residual soil and saprolite rock) were also analyzed. The sedimentary deposits showed interbedding of medium, fine, and very fine sands in the upper portion of the estuary and subordinate silt-clay units derived from lower energy in swamp/mangroves deposits in the lower estuary. Marked geochemical differences occurred among these fluvial sediments. The calculated indices of chemical weathering, such as Chemical Index of Alteration (CIA) and A-CN-K ternary diagram indicate that the estuarine sediments display a wide range of weathering effects, from unweathered derived of Proterozoic gneiss and granitic rocks to intensely weathered site in the swamp deposits of the Piaçaguera River. Phosphogypsum waste stored in the catchment area of the Mogi River showed high concentrations of S, La, Ce, Ca, Sr, Nd, Nb, U, Ba, P, Y and F when compared with the regional rocks, soils and fluvial sediments samples analyzed in the study area, which make it a potential source of environmental contamination. The UCC-normalized patterns, geoaccumulation indexes (Igeo), robust linear regression (RA) and principal component analysis (PCA) were used to identify geochemical anomalies and discuss their probable sources. The principal component scores exhibited strong spatial association with anthropogenic sources. The principal component loading allowed to separate heavy metal elements (Cr, Cu, Ni, Pb and Zn) from the elements related to phosphogypsum waste (e.g., Ce, La, Nd and F). The geochemical anomalies of Ce, La, Nd and F in the fluvial sediments of the Mogi downstream River may be related to phosphogypsum waste in the catchment area, whereas the Cr, Cu and Ni anomalies may be related to fossil fuel, chemical industries and industrial waste deposits which occur near the Pereque and Cubatão rivers.

Highlights

IntroductionStudies on chemical and particulate matter pollution are of great importance to quantify probable risks to human health and ecosystem (CETESB 1985; Spektor et al 1991; Furlan 1998; Klumpp et al 1996; Gutberlet 1997; Rizzio et al 2001; Borrego et al 2007; Tagawa et al 2009; Ogundele et al 2017; Zhang and Zhou 2020; Bontempi 2020), especially in industrialized and urban areas (Lü et al 2019)
Major and trace element geochemistry of the upper estuarine sediments of the Santos estuary and its possible source materials demonstrated that the phosphogypsum waste deposited on the banks of the hydrographic basin of the Mogi and Piaçaguera rivers affected the chemical conditions of these rivers
The concentrations of P, S, F, Nd, Ce, La, Nb, Th and Y in the Mogi downstream river sediments can be directly related to sources of phosphogypsum waste pollution

Summary

Introduction

Studies on chemical and particulate matter pollution are of great importance to quantify probable risks to human health and ecosystem (CETESB 1985; Spektor et al 1991; Furlan 1998; Klumpp et al 1996; Gutberlet 1997; Rizzio et al 2001; Borrego et al 2007; Tagawa et al 2009; Ogundele et al 2017; Zhang and Zhou 2020; Bontempi 2020), especially in industrialized and urban areas (Lü et al 2019). Fertilizer and refinery industries located in Cubatão – Vila Parisi have been responsible, in the past, for the emission of a significant amount of suspended particulate matter with high levels of Si and F (CETESB 1985). Some gaseous and particulate fluorides are assumed to play an important role in forest decline (Gutberlet 1997; Klumpp et al 1996; Tagawa et al 2009)

Methods

Results

Conclusion