Heavy metal contamination of the marine biota along ... - Springer Link

HEAVY METAL CONTAMINATION OF THE MARINE BIOTA ALONG THE RIO DE JANEIRO COAST, SE-BRAZIL

C.E.V. CARVALHO, L.D. LACERDA and M.P. GOMES Departamento de Geoqu~mica Universidade Federal Fluminense Niteroi, 24210, RJ, Brazil

ABSTRACT. A survey is presented on the heavy metal contamination of benthic organisms of the Rio de Janeiro coast, SE Brazil. Metal concentrations were different depending on major pollution sources, element, and species analyzed. The highest concentrations of Zn and Cd occurred in moderately industrialized Sepetiba Bay, while Cu presented its highest content in areas receiving urban wastes. The metals Pb, Ni and Mn did not show any difference among areas. The highest concentration of metals, regardeless of site, occurred in barnacles and oysters, due to the high filtering capacity of these organisms, while the lowest concentrations of all metals occurred in algae species.

I. INTRODUCTION Heavy metals occur under different forms in sea water, and only a fraction of their total concentrations is readly available to organisms (Rainbow, 1985). Therefore, measuring the levels of heavy metals in water and sediments may not reflect the actual toxicity of a given element. The study of metal concentrations in organisms themselves can give a more reliable information on the bioavailability and consequently of the potential damage to the organism's metabolism and to the environment in general (Bryan et al., 1980). The total metal concentration in sea water, its bioavailability and therefore its concentration in marine organisms will be a function of the element involved (e.g. essencial vs non-essencial metal), type of metal source (e.g. urban vs industrial), total metal load, and the organism studied. Therefore, the conjunction of these factors will cause completely different metal distribution patterns among different areas. The present study surveys the concentration of Zn, Cd, Cu, Mn, Pb, and Ni in components of the benthic fauna and flora of the Rio de Janeiro coast, in order to evaluate the effects of metal sources, metal essenciability and organism species on the total metal concentration in these organisms.

Water, Air, and Soil Pollution 57-58: 645-653, 1991. © 1991 Kluwer Academic Publishers. Printed in the Netherlands.

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C.E.V. CARVALHO ET AL.

MATERIAL AND METHODS

The study was carried on four different and contrasting areas (Guanabara Bay, Sepetiba Bay, Angra dos Reis coast and Arraial do Cabo coast) along the Rio de Janeiro State, southeastern Brazil (Figure i). Guanabara Bay is surronded by Rio de Janeiro city and is the most degraded of the four areas. The Bay receives the effluents of circa 6,000 industries mostly chemical and petrochemical and the urba~ wastes of Rio de Janeiro and Niteroi cities which include over 14 x I0 v people. Most of these wastes reach the Bay without previous treatment (Lacerda, 1982; Rezende and Lacerda, 1986). Sepetiba Bay, located at approximately 60 km south of Rio de Janeiro city, is only moderately polluted by industrial effluents from metallurgical plants located at the Bay's north coast. However, the effluents of a Zn-Cd ore processing plant has caused significant contamination of the Bay's environment. Urban wastes are practically inexistent due to the low population density of the area (Pfeiffer et a_~l., 1985; Lacerda et al., 1987). The Angra dos Reis coast is a typical tourist area located circa 130 km south of Rio de Janeiro city. Industrial activity is negligeable However, accelerated land reclamation has caused an increase in population density of the area resulting in localized discharges of urban wastes (Lacerda et al., 1982; Guimaraes et al., 1982). The Arraial do Cabo coast is also a tourist area free of industrial and urban wastes contamination. The region is a major fishing area of Rio de Janeiro State due to the occurrence of an upwelling of platform nutrient-rich waters. No study so far has documented metal contamination in the area (Rezende and Laeerda, 1986; Muricy, 1989).

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HEAVY METAL CONTAMINATION OF THE MARINE BIOTA

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Samples of the most representative local benthic biota were collect ed by divers at a maximum depth of 3 m on the four studied areas. After sampling, the organisms were fully washed in local seawater, placed in : plastic bags and frozen for transport. In the laboratory the samples were oven dried (809C/24hr), ashed in a mufle furnace (4509C/24hr) and the ashes digested in a hot acidic solution (HCI:HNOR conc. 1:3), evaporated till dry and redissolved in 0.1N HCI. Metals~Cd, Pb, Ni, Zn, Cu and Mn were measured in the 0.1N HCI extract by conventional flame atomic absorption spectrophotometry, using background correction and standard reference material. 3. RESULTS AND DISCUSSION Metal concentrations in all organisms analysed are presented in Figures 2,3,4 and 5, for Guanabara Bay, Arraial do Cabo coast, Sepetiba Bay and Angra dos Reis coast, respectively. Zinc was the element that presented the highest concentrations among the studied organisms, this fact may be a function of the importance of Zn in the composition of approximately 90 different enzimes of the animal metabolism (Bowen, 1979~. The hihest values were found in Se~tiba Bay (Fig. 4) (15,514 mg.kg -~, in Megabalanus sp. and 9,500 mg.kg , in Crassostrea brasiliana), these concentrations probably reflect the discharges of the industrial park located in that area (Lacerda et al., 1987; Pfeiffer et al., 1985). Th_~ lowest values were found in ~ngr-a dos Reis coast (FT . ~) (6.4 mg.kg - in Ulva fasciata), however, all the algae species presented low Zn concentrations irrespectively of the area sampled. Independent of the area studied, Cu presented higher values in moluscs and crustaceans than in algae, probably reflecting the important role played by this metal in the respiratory metabolism of these organisms (Bowen, 1979). The highest Cu eoneentrations were found ~ Angra dos Reis coast (Fig. 5) and Guanabara Bay (Fig. 2) (227 mg,kg in Crassostraea brasiliana)land the lowest values were found in gepetiba ~ay (Fig. 4) (3.0 mg.kg - in Ulva faseiata). These results may be explained by the fact that Cu is present in high coneentrations in urban wastes (Rebello et al., 1986), which is more serious in Guanabara Bay and Angra dos Reis coast than in the other two areas. Cadmium presented tile lowest concentration of all metals studied. Sepetiba Bay (Fig. 4) was thelarea which presented the highest values for this element (35.9 mg.kg in Megabalanus sp.) strengthning the hypothesis of industrial pollution in the area. In fact other authors have reported high Cd concentrations in other organisms of Sepetiba Bay (Pfeiffer et al., 1985). The other areas presented similar concentration levels indicating natural background Values for Cd throughout the rest of Rio de Janeiro coast. The other metals (Pb, Mn and Ni) did not present significant differences on their concentrations among the areas. However, different concentrations among organisms were significant independent of the area. For example, contrary to all other metals, Mn concentrations were much higher in algae than in animals. This variability is a consequence of the different physiology of each organism (Amiard et al., 1987) and their

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Figure 2. Heavy metal distribution in the benthic marine biota of Guanab~ra Bay, Rio de Janeiro State coast, SE Brazil. Val~es in mg.kg - dw.


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Figure 3. • Heavy metal distribution in benthic marine biota of Arraial do Cab_~ coast, Rio de Janeiro State, SE Brazil. Values are in mg .kg dw.

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Figure 4. Heavy metal distribution in benthic marine biota of Sepetiba Bay, Rio de Janeiro coast, SE Brazil. Values in mg.kg -I dw.


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Figure 5. Heavy metal distribution in benthic marine biota of A~gra dos Reis coast, Rio de Janeiro, SE Brazil. Values are in mg.kg dw.

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feeding habits (Ikuta, 1988). The suspended particulate matter is the principal carrier of heavy metals in coastal regions of Rio de Janeiro state (Lacerda et al., 1987) This explains the higher concentrations found in filter feeding organisms, like the oyster Crassostraea brasiliana and the barnacle. In these organisms detoxification mechanisms generaly involve the accumulation of high levels of heavy metals bound to insoluble metalliferous granules or to soluble metal binding-ligands, which results in high body content of metals (Rainbow, 1987). These mechanisms are particularly efficient for Zn (Rainbow, 1985) and therefore explains the extremely high Zn concentrations found in filter feeding anaimals in Sepetiba Bay. The adsorption of metals to suspended particles will, on the other hand, decrease metal availability to the algae, since in these plants metal uptake is basicaly from water. Two main mechanisms are involved in the metal uptake process in algae species : passive adsorption of metallic ions on the external surface of algae tissues, involving ion exchange between the medium and charged sites on the algae surface; and active absorption of ions through the celular membrane involving carrier proteine mediators of moderate selectivity (Rai et al., 1981). Therefore these mechanisms incorporate basicaly dissolved ions. As in most of the areas metals are supposed to be associated with suspended particles, this would decrease metal uptake by algae. Regardeless of the area sampled the algae always presented the highest conE~ntrations of Mn among the studied organisms (e.g. up to 214.9 mg.kg in Dictiota dichotoma from Arraial do Cabo coast, Fig. 3). This may be related to the important role played by this metal on the algae growth, the algae enzimatic system (e.g. malic dehydrogenase and oxalosuccinic decarboxylase) participating in the Krebs cycle (Rai el al., 1981). 4. CONCLUSIONS Our results show that the R-o de Janeiro coast presents two areas where heavy metals are a contamination problem. Sepetiba Bay, which suffers the impact of an industrial park with high Zn and Cd concentrations in its biota, and Angra dos Reis coast, which is starting to show the effects of urban wastes released by the growing population, which results in the contamination of the local biota with Cu. Guanabara Bay presents a different situation where high eutrophicat ion from untreated urban wastes interacts with heavy metals from industrial origin. Various authors reported high metals concentrations in the Bay's sediments (Rebello et al., 1986). However, they seem to be unavailable for biological uptake, resulting in a relatively small contamination of the local biota of the Bay. 5. ACKNOWLEGMENT S This study was supported by Conselho Nacional de Desenvolvimento Cient~fico e Tecnoiogico (CNPq) and FAPERJ. We also thank the many students who helped us with field work.


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6. REFERENCES Amiard, J.C., Amiard-Triquet, C., Berthet, B. and Metayer, C.: 1987, J. Exp. Mar. Biol. Ecol. 106:73. Bowen, J.J.M.: 1979, Environmental Chemistry of the Elements. Academic Press, London, 333p. Bryan, G.W., Langstron, W.J. and Hummerstone, L.G.: 1980, Mar. Biol. Assoc. U.K. Spec. Publ. I:i. Guimaraes, J.R.D., Lacerda, L.D. and Teixeira, V.L.: 1982, Rev. Bras. Biol. 42:553. Ikuta, K.: 1988, Nippon Suisan Gakkaishi. 54,811. Lacerda, L.D., Pfeiffer, W.C. and Fiszman, M.: 1987, Sci. Tot. Environm. 65:163. Lacerda, L.D., Pfeiffer, W.C. and Fiszman, M.: 1982, CiSnc. Cult. 34:921. Lacerda, L.D.: 1982, Rev. Bras. Biol. 42,89. Luoma, N.S.: 1983, Sci. Tot. Environm.28,1. Muricy, G.: 1989, Rev. Bras. Biol. 49:347. Pfeiffer, W.C., Lacerda, L.D., Fiszman, M. and Lima, N.R.W.: 1985, CiSnc. Cult. 37,297. Rai, L.C., Gaur, J.P. and Kumar, H.D.: 1981, Biol. Rev. 56,99. Rainbow, P.S.: 1985, Inter. J. Environm. Studies. 25,195. Rainbow, P.S.: 1987, In: Barnale Biology (J.A. Southward, ed.). A.A. Balkema, R o t t e r d a m ~ i e l - d . Rebello, A.L;, Haekel, W., Moreira, I., Santeli, R. and Schroeder, F.: 1986, Mar. Chem. 18,215, Rezende, C.E. and Lacerda, L.D.: i986, Rev. Bras. Biol. 46,239.