Heavy metals in benthic organisms from Todos os Santos Bay, Brazil

Gm Amado-Filho,Mf Rebelo,Cs Karez,Ce Rezende,Wc Pfeiffer,Lt Salgado

doi:10.1590/s1519-69842008000100013

Abstract

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae) in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.

Highlights

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities
Among the organisms sampled in TSB, C. rhizophorae exhibited the highest concentrations for Cu (526.1 ± 153.8 μg.g-1), Cd (8.29 ± 2.43 μg.g-1), Ni (1990.9 ± 91.4 μg.g-1) and Zn (4733 ± 1291 μg.g-1); while H. wrightii exhibited the highest concentrations for Cr (12.2 ± 4.9 μg.g-1), Fe (5664 ± 460 μg.g-1), Mn (803.5 ± 47.8 μg.g-1) and Pb (13.6 ± 2.0 μg.g-1); and P. gymnospora exhibited significantly higher values for Al (4412 ± 133 μg.g-1)
A comparison between the obtained data with other results of contaminated Brazilian coastal areas by using the same studied species shows that the metals Cd, Cu and Ni from TSB were in the similar range of concentrations (Amado Filho et al, 1999; Rebelo et al, 2003)

Summary

Introduction

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. For tropical Western Atlantic coastal areas previous studies have shown three benthic organisms as good bioaccumulators of metals: the oyster Crassostrea rhizophorae (Guilding, 1828) exhibits high filtration rates of suspended particles and a high metal bioaccumulation capability (Lima et al, 1986; WallnerKersanach et al, 2000; Rebelo et al, 2003), the brown seaweeds, specially Padina gymnospora (Kuetzing) Sonder, 1871 exhibit high capability of accumulating metals from the dissolved fraction of water column (Amado Filho et al, 1999) and the seagrass Halodule wrightii Ascherson, 1868, which is an important contributor to primary production (Klumpp and Van der Valk, 1984), take up metals from both water, through leaf surfaces, and from sediment and interstitial water, by way of their roots (Pulich, 1980; Amado Filho et al, 2004). The mollusks Anomalocardia brasiliana (Gmelin, 1791), Brachidontes exustus (Linnaeus, 1758) and Crassostrea rhizophorae were analyzed for their metal content in TSB (Tavares, 1983, Wallner-Kersanach et al, 1994; 2000) and it was shown that differences between TSB area and control sites were detected only for C. rhizophorae

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