Journal of Coastal Research
SI 39
pg - pg
ICS 2004 (Proceedings)
Brazil
ISSN 0749-0208
Study of the Toxicity of Marine Sediments of Babitonga Bay – Brazil
M. Bonatti†, S. Furlan†, S. Manente‡ and G. Perin‡
‡Università Ca’ Foscari Venezia
Dipartimento di Scienze
Ambientali
Santa Marta, Dorsodoro 2137
30123 Venezia, Italy
guiper@unive.it
manente@unive.it
†UNIVILLE
Department of Chemistry and
Deapartment of Chemical Engineering
Caixa Postal 246, 89201-972
Joinville, SC, Brazil
mbonatti@univille.edu.br
sfurlan@univille.edu.br
ABSTRACT
BONATTI, M.; FURLAN, S.; MANENTE, S. and PERIN, G., 2003. Study of the Toxicity of Marine Sediments
of Babitonga Bay - Brazil. Journal of Coastal Research, SI 39 (Proceedings of the 8th International Coastal
Symposium), pg – pg. Itajaí, SC – Brazil, ISSN 0749-0208
The contamination in aquatic environments, in the last decades, is undeniable. One of the most important sources
of contamination are industrial wastewaters. For this reason, the study of pollutants coming from anthropic origin
on the Babitonga Bay should be considered as an important tool for the local government, in order to create
programs for preserving this kind of ecosystems. One of the ways for determining pollution in aquatic systems is
studying bio-availability and toxicity of trace metals in contaminated sediments available to aquatic animals, by
the use of speciation techniques and bioaccumulation studies. The heavy metals studied for this purpose were Cr
and Zn. According to results obtained, the concentration values for Zn were very high at the first (0.0 – 17.78
mg.kg-1 dry sediment), second (0 – 64.27 mg.kg-1 dry sediment) and third (11.8 – 290.77 mg.kg-1 dry sediment)
GPHs for all site samples, as well as the high concentration values for Cr at the third (1.12 – 13.7 mg.kg-1 dry
sediment) GPH. Approximately, 85% of Zn and 45% of Cr were found at the first three phases. These results
indicate a relatively polluted sediment. Then, in order to verify the bio-availability of the metal content of
Babitonga Bay sediments to the water column, bioaccumulation analysis were performed. Three commercial
species of edible fish, caratinga (Eugerres brasilianus), robalo (Centropomus paralellus) and tainhota (Mugil
platanus) were selected and collected for this study. The levels of metals detected on the fish muscles of all the
mentioned species are acceptable for human consumption.
ADITIONAL INDEX WORDS: heavy metals, sediments, speciation, fish.
INTRODUCTION
Babitonga Bay is located on the northern coast of Santa
Catarina State, Brazil, between the continent and the island of São
Francisco do Sul (26º00’ – 26º26’ S and 48º29’ – 49º12’ W,
Figure 1). The Babitonga Bay has an extension of 154 km2,
representing one of the most important estuarine formations in the
south of Brazil. However, agricultural runoffs, agricultural and
domestic effluents go directly into the bay through drains,
channels and rivers. In addition, smelting, galvanic and textile
factories factories located on the vicinity of the bay also discharge
effluents into the bay.
Bottom sediments are known as the principal sink for heavy
metals in an aquatic environment, and may be introduced to water
by both natural and anthropogenic sources ( PEMPKOWIASE et al.,
1999). However, when the environmental conditions change, as a
result of either physical disturbance (pH, sediment redox potential,
etc.) (BOUGHRIET et al., 1992), or diagenesis (PETERSEN et al.,
1995), sediments can act as a source of pollutants even after a long
time of the cessation of direct discharges.
To assess the environmental impact of polluted sediments, the
determination of the total concentration of metals does not give
any information regarding the form in which metals are bounded
to the sediments (metal carbonates, oxides, sulfides,
organometallic compounds, etc.). The chemical form of the metals
found on the sediments is very useful for determining the degree
of association of metals in the sediments, to what extent they may
be remobilised to the environment, and also for distinguishing
metals of lithogenic origin from those of anthropogenic origin.
The main goal of operational speciation studies is to convert the
metals bound on the sediment phases into soluble forms by the use
of chemicals for decreasing pH and increasing oxidizing strength
in order to remove the operationally-defined host fractions. Many
of the sequential extraction schemes employed are based on the
five-stage procedure of TESSIER et al. (1979): (1) loosely metals
adsorbed by the surface of sediments particles; (2) bounded to
carbonates;
(3)
bounded
to
iron
and
manganese
oxides/hydroxides; (4) complexed by organic matter; and (5)
incorporated into clay mineral lattices (Fergusson, 1990).
According to RUBIO et al. (1991), metals of anthropogenic origin
are mainly obtained on the first extractions.
Any study has determined metal speciation on the Babitonga
sediments, although this is of critical importance in order to
determine the likely behaviour of metals in aquatic systems and
their potential for biological uptake.
Agriculture, aquaculture and fishing are the primary activities
of the people living on the Babitonga Bay. Therefore, there is a
very important concern regarding the people’s health whom are
fed by fish catch in this area. Since metal content in the tissues of
fish is species-dependent, three commercial species of edible fish,
caratinga (Eugerres brasilianus), robalo (Centropomus paralellus)
Journal of Coastal Research, Special Issue 39, 2004
Toxicity of Marine Sediments.
phase 4. The geochemical phases were called GPHs, indicating
with a number the extraction step.
The GPHs were determined as follows. Ten grams of dry
sediment was treated with 40 ml of 1M NH4OH, shaken for 1 h,
settled overnight, filtered with 0,45µm filter, washed three times
with distilled water metal-free; the residue (1) was dried overnight
at 105ºC. This solution contained the first GPH. Three grams of
the residue (1) was mixed with 40 ml of 1M NaOAc plus 1 ml of
HAc, shaken for 2 h, settled for two nights, filtered and washed.
This solution contained the second GPH. The residue (2) was
dried overnight like residue (1). All the residue (2) was mixed
with 40 ml NH2OH.HCl in 0.01 M HNO3, shaken for 45 min.,
settled for two nights, filtered and washed. This solution contained
the third GPH. The residue (3) was dried overnight like residue
(1). All the residue (3), treated with 6 ml of 0.02 M HNO3 plus 10
ml of 30% H2O2, was acidified with HNO3 at pH 2, heated to 75ºC
for 2 h and mixed with 30% H2O2 at pH 2. The mixture was
heated for 4 h in an oven. After cooling, it was mixed together
with 15 ml of 3.2 M NH4OAc in 20% (v/v) HNO3, and settled for
two nights. This cleared solution contained the fourth GPH. The
residue (4), washed accurately, was dried in an oven overnight like
residue (1). Finally, the residue (4) was mixed with 40 ml of 0.04
M NH2OH.HCl in 25% HAc, heated to 98ºC for 5 h, settled for
two nights and filtered. This solution contained the fifth GPH. For
HF total metal content, 0.5 grams of dry sediment was treated in a
Teflon container sealed with a Teflon cap (Teflon Bomb) in an
Figure 1. Geographic location of Babitonga Bay (1= Lagoa do
Saguaçu, 2= Rio Palmital, 3= Vila da Gloria, 4= Porto Sao
Francisco do Sul, 5= Canal do Linguado).
and tainhota (Mugil platanus), were selected and colleted from the
bay for the present study.
The aims of this study are to determine: (a) the concentration of
Cr and Zn in the sediments of the bay and the chemical forms in
which they occur, (b) the metal bioaccumulation on the muscles of
edible fish and the possible risk associated with human
consumption of these fish.
METHODOLOGY
Sediment samples were collected from five sites along the
Babitonga bay (Figure 1) using a Petersen dredge, getting the first
20 cm of superficial sediment, carefully screened for determining
the presence of animals and for checking the colour, the structure
and the smell, then put in glass jars and frozen. Depending on the
bottom structure, each station was sampled several times
(minimum three) to get a representative sample obtained by
carefully mixing the different sub-samples.
The sequential extraction procedure was a slight modified
version of the technique proposed by CHESTER AND HUGHES
(1967) and TESSIER et al. (1979). The five GPHs obtained have the
same meanings as in CHEN et al. (1976): i. e. phase 1, ionexchangeable metal; phase 2, metal bounded to carbonates; phase
3, easily-reducible metal (bounded to oxides of manganese and
non-crystalline lattice iron); phase 4, metal bonded to organics and
sulfides; phase 5, reducible metal (bonded to iron oxides)
remaining after the coating destruction by oxidative treatment of
Figure 2. Percentage concentration (%) and mg.kg-1 dry sediment
for Cr and Zn at each of the five geochemical phases of the
modified Tessier et al. (1979) method.
Journal of Coastal Research, Special Issue 39, 2004
Bonatti et al.
Table 1: Bioaccumulation of metals in the fish of Babitonga Bay
-1
Ichtic Species
Eugerres brasilianus
Centropomus paralellus
Mugil platanus
Permitted limits of heavy
metals (Health’s Ministry)
Content of metals (µg.g , wet
weight) ± standard deviation
Zn
Cr
9.28 ± 0.65
0.06 ± 0.004
12.71 ± 0.56
0.08 ± 0.006
4.40 ± 1.17
0.06 ± 0.009
100
0.10
oven with 0.5 ml of distilled water, 1.5 ml of concentrated HF and
3.0 ml of aqua regia (HCl conc. + HNO3, 3:1). All the solutions
were examined by flame atomic absorption analysis (Spectra AA
250 plus, Varian).
The fish analysed were obtained from a local fish market, sliced
for muscle samples and finally liophilizated. Then, aliquots of
0.5g of an oven-dried (105ºC, 18 h) and homogenized sample
were wet digested in a glass vessel with 10 ml of concentrated
HNO3 and then agitated for 18 h at a room temperature. After
digestion, the samples were filtered with a 0.45 µm filter and
diluted with distilled metal-free water up to 50 ml. The metal
analysis were carried out by using an atomic absorption
spectrophotometer (Spectra AA 250 plus, Varian).
RESULTS AND DISCUSSION
The concentration in percentage (%) of Cr and Zn determined
at each extraction step for the five different location of sediment
samples are illustrated in Figure 2.
Partitioning patterns for Cr and Zn on the different sediment
samples showed that the distribution of heavy metals is not
uniform over the whole Bay. This can be explained by the
differences on the heavy metals sources, the prevailing physicchemical conditions, complex reactions such as adsorption,
flocculation and redox conditions existing on the Bay.
The smallest values of Cr were observed at the first GPH (ionexchangeable metal) and second GPH (metal bounded to
carbonates) (0% to 7%), for all site samples. The highest values
concentration (%) were observed at the third GPH (easilyreducible metal, bounded to oxides of manganese and noncrystalline lattice iron) (21% to 62%) and fourth GPH (metal
bounded to organic substances and sulfides) (21% to 68%), in all
site samples. The high values of metals found on the fourth GPH
(organic phase) are not alarming, since they are not considered
very mobile or available and therefore generally associated with
stable, high molecular weight humic substances, which slowly
release small amounts of metals (SINGH et al., 1998).
According to PERIN et al. (1997), the first, second and third
GPHs are considered bio-available phases and the fourth and fifth
GPHs are considered non-bioavailable phases. Due to the low
values concentration observed for Cr at the first and second GPHs,
this element should be considered as non-bioavailable, but since
very high values concentration were obtained at the third GPH (for
all the site samples), then Cr contained on the sediment samples of
the Babitonga Bay must be considered bio-available to aquatic
media.
According to PEMPKOWIASE et al. (1999), heavy metals of
anthropogenic origin are generally introduced into the
environment as inorganic complexes or hydrated ions, which are
easily adsorbed by the sediment surface of particles through
relatively weak physical and chemical bonds. Thus, heavy metals
of anthropogenic origin are found predominantly as labile
extractable fractions (first GPH) in sediments.
For Zn, the highest values (at all site samples) were observed at
the third GPH (69% to 89%) while for the fourth and fifth GPHs
the concentration values (%) were relatively low (average 7.4%).
The Zn values concentration at all bio-available phases were
higher than those for Cr. This indicates that this metal is more
easily available to aquatic life than Cr. Other past researchers also
described a similar behavior of these metals in sediments:
ALVAREZ-IGLESIAS et al. (2003), TOKALIOGLU et al. (2000) and
PERIN et al. (1997).
Table 1 shows the heavy metal concentration on three different
fish of Babitonga Bay and the permissible limits proposed by the
Ministry of Health in Brazil (1977). The concentration of Zn was
higher than the concentration of Cr for all species analysed. The
Zn values found on the Babitonga Bay fish muscles are in
concordance with the results obtained from the metal
concentration studies performed in the fish of Ataturk Dam Lake
(Euphrates), Turkey by KARADEDE AND UNLU (2000).
CONCLUSIONS
Trace elements concentration depends not only on industrial
and household waste inputs but also on the geochemical
composition of the area. However, the concentration values of Zn
were very high at the first, second and third GPHs, as well as the
concentration values of Cr at the third GPH. Thus, these
concentrations of Zn and Cr have resulted from anthropogenic
influences. The metal contents of Zn and Cr found on the
Babitonga Bay sediments are characteristic of polluted sediments.
In spite of this situation, the levels of Zn and Cr found on the fish
muscles are acceptable for human consumption. However, if no
precaution and action are taken in short term, a potential danger
may occur in the future depending on the agricultural and
industrial development in this region.
LITERATURE CITED
BOUGHRIET, A., OUDANE, B., FISCHER, J.C., WARTEL, M.,
and LEMAN, G., 1992. Variability of dissolved Mn and Zn
in the Seine Estuary and chemical speciation of these metals
in suspended matter. Water Research 26, 1359-1378.
CHEN, Y.K., GUPTA, S.K., SYCIP, A.Z., LU, J.C.S.,
KNEZEVIC, M., and CHOI, W.W., 1976. Research study on
the effect of dispersion, settling, and resedimentation on
migration of chemical constituents during open-water
disposal of dredged materials. Dredged Material Research
Program Rep. D-76-1. Environ. Effects Lab., US Army
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CHESTER, R., and HUGHES, M.J., 1967. A chemical technique
for the separation of Fe-Mn minerals, carbonate minerals and
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Toxicity of Marine Sediments.
RUBIO, R., LOPEZ-SANCHEZ, J.F., and RAURET, G., 1991. La
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ACKNOWLEDGEMENT
Special thanks to the UNIVILLE for its financial support
necessary for the sampling campaign and the special pre-treatment
required for the fish transport to Italy.
Journal of Coastal Research, Special Issue 39, 2004