- Email: [email protected]
Chromium contamination in sediment, vegetation and fish caused by tanneries in the State of Minas Gerais, Brazil
The Science
of the Total
Environment
207 (1997)
l-11
Chromium contamination in sediment, vegetation and fish caused by tanneries in the State of Minas Gerais, Brazil C.P. Jord5o” , J.L. Pereira, G.N. Jham Departamento
de Quimica,
Uliversidade Received
Federal
12 May
de EGosa 36571-000,
1997; accepted
I/isosa, Minas
Gerais, Brazil
30 July 1997
Abstract
In order to evaluatethe chromiumcontaminationfrom tannery dischargesinto rivers in the State of Minas Gerais, Brazil, samplesof fluvial sediment,vegetation and fish were collected and submitted to chemical analysis.The chromium content in the sampleswasmeasuredby atomic absorptionspectrophotometry.Metal inputs were related to effluent dischargesinto the rivers. High concentrationsof chromiumwere found in sampleswhen comparedwith controls. Sedimentinvestigationsindicated strong enrichment and high geoaccumulationindices,while chromium concentrations in the analyzed vegetation were higher than those normally found in these materials. Chromium levels in fish exceeded35 times the Brazilian recommendationvalue for human intake. 0 1997Elsevier Science B.V.
1. Introduction Aquatic contamination by heavy metals is very harmful since these elements are not degradable in the environment and may accumulate in living organisms (Jardim, 1983). Several studies on the pernicious effects of heavy metals in organisms, e.g. chromium and its carcinogenic compounds have been reported (Sala et al., 1995). Chromium is used in substantial amounts by the leather tanning industry (FGrstner and Wittmann, 1981). It cannot be predicted on how long the environment can integrate toxic wastes. Therefore, con-
* Corresponding
author.
004%9697/97/$17.00 0 1997 Elsevier PZZ SOO48-9697(97)00232-5
Science
B.V. All rights
centrations of heavy metals, including chromium, must be determined in order to evaluate their environmental effects. Several tanneries operate in the State of Minas Gerais and produce approximately 10% of Brazilian leather (Perez, 1991). Approximately 75 of them are legally registered, but most of them discharge their wastes directly into the rivers without any previous treatment (Fundac$o Estadual do Meio Ambiente, 1994). It is a well-known fact that chromium is essential for leather quality, such as strength, elasticity and thickness (Grozza, 1984), however, no determination of heavy metal concentrations have been carried out in the rivers near tanneries in the State of Minas Gerais. reserved.
2
C.P. Jordrio
et al. /The
Science of the Total Environment
The knowledge of the metal concentrations in river sediments is important from both a geochemical and an environmental view point (Agemian and Chau, 1975). Fluvial sediments constitute a stabilization factor between soluble and insoluble pollutants within aquatic environments, due to their presence over a long period of time in rivers and their capacity to neutralize drained off discharges (Agudo, 1987). High levels of metals in soils do not necessarily reflect elevated doses in plants since other factors, such as the pH, cation exchange capacity, organic matter and humidity may also influence their uptake (Albasel and Cottenie, 1985). Thus, chromium contents in leaves show little relationship with the overall concentrations of Cr in soils (McGrath and Smith, 1993). However, waste spillage on land may contaminate the underground waters. Fishes are commonly used as an indicator for pollution control in aquatic environments. Relatively low amounts of Cr, Pb and Zn have been reported in fish when compared to those of abiotic sites (Fernandes et al., 1994). Thus, it is reasonable to assume that abiotic niches of ecosystems are enhanced by high heavy metal levels (Pfeiffer et al., 1985). This does not mean, however, that pollutants are innocuous through fish consumption. No reliable values of Cr concentrations are available in fluvial sediment, vegetation and fish from waste discharge of tanneries in the State of Minas Gerais. Thus, the purpose of this article is to study the distribution of this element in the river systems near tanneries in Brazil. 2. Material
and methods
South-eastern regions of the State of Minas Gerais were studied since leather factories discharge waste waters into the local rivers without any previous treatment. The sampling locations are shown in Figs. 1 and 2. Samples from an uncontaminated spring (Espirito Santo Rivulet in Belmiro Braga) close to the studied area were investigated to get regional background values. Sediment, vegetation and fish samples were obtained in the dry season at sites up- and down-river with respect to tanneries and kept at 4°C until analysis.
207 (1997)
l-11
Surface sediments were scooped at river-shores, excess surface water was skimmed off and sediments placed into plastic bags. The samples were oven-dried at 105°C and passed through an 80 mesh sieve. Another set of samples were ovendried at 60°C for 48 h and passed through a 9 mesh sieve for pH measurements. For chromium determination, 1 g of the sediment was first digested with 10 ml of concentrated HNO, solution to near dryness; aliquots of 10 ml of concentrated HF and 2 ml of concentrated HClO, solutions were added and the mixture was evaporated to near dryness. Finally, the residue was dissolved in 2 ml of 12 N HCl and diluted to 25 ml with deionised water. The pH of sediment was measured in both 1 M MC1 solution and distilled water (solid/solution ratio = 1:2.5). Plants (Paspalum sp., Panicum sp., Brachiaiia sp., Typha sp., Ciperacia sp., Commelina sp. and Sorghum sp.) were cut above the river water level and washed before trace element analysis. The clippings were stored in acid-washed plastic bags, transported to the laboratory at 5°C thawed and sectioned in pieces. The leaves were dried at 105°C for 24 h and a 10-g portion was digested at room temperature with 10 ml of concentrated HNO, solution. A second portion of HNO, (20 ml) was added and the mixture evaporated at 150°C. Finally, solutions of concentrated HNO, (10 ml) and HClO, (5 ml) were added and the mixture was evaporated to near dryness. The resultant solution was diluted with deionised water to 25 ml. Metal concentrations in decapitated and eviscerated fishes were determined in visceral mass and muscle tissues of Oreochomis sp., Astyanax sp., Cichlasoma sp. and Hypostomus sp. Fish were angled only at a few sites since sufficient suitable material was not available for analyses. The fish weight varied between 14.4 and 66.8 g (8.9-19 cm in length) and the heads and tails were discarded. Samples were oven-dried at 105°C for 48 h and ground in a ceramic mortar. Portions of visceral mass (1 g) and muscle tissue (5 g) were individually digested at 150°C with 20 ml of concentrated HNO, solution and the mixture evaporated to near dryness. The samples were further digested at 150°C with 10 ml of concentrated HNO, and 5
C.P. Jordiio et al. /The Science of the Total Environment 207 (1997) I-11
3
(bl
(0)
O-SAMPLING
LOCLTION
IPATINGA VALE
DO
AGO
*\usr \
O-S4MpLING
LOC4TION
cl-T4WERY 0
BT-GAl4NO
0
JW-JOSg
0
47-
0
SW-sio -.-
Fig. 1. study
areas: (a) Ipatinga;
(b) Matias
ml of 30% (w/v) H,O,, and the mixture evaporated to near dryness. When necessary, due to the high fat content of fish, the sampleswere also subsequently digested with a solution of concentrated HNO, (5 ml) and HClO, (5 ml) and diluted with deionised water to 25 ml. Leather chippings were also collected in the tannery located in Uba. The sampleswere ovendried at 60°C for 24 h. Subsamples of 1 g each
Barbosa;
D4
(c) Dores
HARIOUINHA
ARRVOA HARCOS MUNKIP4L
OlSTRlCT
de Campos.
were first digested with solutions of concentrated HNO, and HCl (10 ml each). To the mixtures were added solutions of concentrated HNO, (10 ml) and HClO, (5 ml) and diluted with deionised water to 25 ml. Metal concentration was measured with a Carl Zeiss JENA, model AAS atomic absorption spectrophotometer by direct aspiration of the solution into a nitrous oxide-acetylene flame.
4
C.P. Jodio
et al. / The Science of the Total Environment
207 (1997) l-11
I
I
JUiZ
DE FORA
I
Fig. 2. Study areas: (a) Ressaquinha; (b) UbB; (c) Juiz de Fora.
C.P. Jordiio
et al. /The
Science
of the
Total Environment
Certified analytical grade reagents were used for analysis. Blanks were run through all experiments to control any contamination. 3. Results
and discussion
pH values
Site No.
pH in distilled 1 2 3 4 5 6
from
various
sampling
1-11
5
Vale do Ago (literally ‘Steel Valley’) in the State of Minas Gerais (Jordgo et al., 1996). The mean chromium concentrations of three replicates in the sediments of each sampling station are presented in Table 2. It was observed, in general, that the Cr concentration in site 3 of each region (near the waste discharge points) is higher than those found from sites 1 or 2 (upriver with the tanneries). For instance, the contamination of the sediment collected at site 3 in Ipanema Stream was attributed to the Kapard tannery of Ipatinga, since its waste discharge is located at a distance of only 50 m from this site (Fig. la). The sediment samples, gathered in the dry season showed Cr concentrations ranging from 14.2 to 266 pg 8-l in Ipatinga. High contamination of sediments from the Piracicaba River in Ipatinga collected in the dry season has also been observed. Thus, the Cr levels in the rainy season showed less contamination, since a smaller volume would obviously exhibit a higher concentration of pollutants (Jordso et al., 1996). A uniform distribution of Cr concentrations in sediment samples along the Paraibuna River in Matias Barbosa was observed (Fig. lb). The maximum value was found in site 3 and was approximately twice as high as that of the control area
The pH of the sediments measured both in KC1 solution and distilled water ranged from 3.7 to 7.5 (Table 1). Addition of KC1 to the solution maintains its ionic strength and reduces the pH change due to dilution (Alvarez et al., 1994). In general, the pH measured in KC1 solutions gave lower values than those in distilled water. This seems reasonable since a higher proton content is to be expected from KCl-amended sediments. The low pH values of some sites suggests a high negative charge on the clay component. Sample site 6 in Ipatinga (Ipanema Stream) showed a considerably higher pH value (7.5) than the others. This may be explained by assuming that the sediment collected at this site had a high dredged sand content. Sediment pH values were similar to those of an uncontaminated area (Espirito Santo Rivulet in Belmiro Braga), i.e. 4.5 in H,O and 3.9 in KCl. Values of pH ranging from 4.3 to 6.4 have been reported for sediments from the Piracicaba and Dote rivers, within the
Table 1 Sediment
207 (1997)
sites
Location Ipatinga
Matias
6.7 3.8 6.6 4.5 6.3 7.5
5.5 5.4 5.6 5.9 5.4 -
4.8 3.7 6.4 4.2 6.1 7.3
5.5 5.0 5.0 5.1 4.8
Barbosa
Dores
de Campos
Ressaquinha
Uba
Juiz de Flora
4.1 5.2 5.4 5.8 5.4 5.6
5.4 5.0 5.1 4.9 3.7
4.5 5.3 5.2 4.9 4.9 4.7
5.5 6.9 7.2 6.9 7.1 -
4.0 4.5 5.0 4.3 4.7 4.3
4.3 4.5 4.5 4.8 3.7
4.1 4.7 5.1 4.9 4.8 4.3
4.3 5.4 6.5 5.0 5.0
water
pH in 1 M KC1 solution 1 2 3 4 5 6
6
C.P. Jordiio
Table 2 Chromium Site No.
concentration
“Mean bGlobal ‘Value dValue
from
various
Science of the Total Environment
sampling
sites ( pg g-l,
207 (1997) 1-11
dry wt.)“* bZ ‘. d
Location Ipatinga
1 2 3 4 5 6 7
in sediments
et al. /The
19.0 14.2 266 37.3 24.1 57.8
+ + + & i +
9 5 95 17 2 2
Matias
Barbosa
80.0 60.1 93.0 87.9 86.2
12 20 3 16 9
+ f i + k
Dores
de Campos
340 + 31.2 k 2878 + 156 i 131* 897 +
7 21 78 12 28 0.3
Ressaquinha
Ub6
70.1 87.0 98.5 74.0 43.9
75.0 f 68.9 f 1531+ 334 + 168 * 243 + 120*4
f + + + +
7 16 3 14 5
of three replicates f standard deviation. average value for fluvial sediments, 90 pg 8-l (Maim et al., 1989). from a non-polluted region (Espirito Santo Rivulet in Belmiro Braga), 26.3 pg g-i. from a non-industrialized region (Grande, Negro and Preto rivers, near the studied
(53 pg g-i). However, the Cr concentration found at site 4 was three times the value (26.3 pg g-l) obtained from the sediment of the non-mineralized nor polluted region of Belmiro Braga (Table 2). Although the Matiense tannery had been shut-down at the time of sample collection, the high Cr concentration might be attributed to the metal retention capacity of sediments, as well as to the high industrialization of the region. A comparison of Cr concentrations for fluvial sediments with those of non-industrialized areas near the studied sites, showed Cr inputs from several tanneries (Table 2). Thus, 79% of samples showed Cr concentrations above the mean value (53 Fg g-l> found in those areas (Torres, 1992). The dark sediment from site 3 of Dores de Campos (Fig. lc) was very contaminated, its Cr concentration being 54 times higher than the control value. This result reveals that the Cr level at site 3 exceeded those found in the vegetation and fish samples analysed. Nevertheless, sediment samples collected upriver with the tanneries at both sites 1 (AGude Stream) and 4 (Patusca Stream) showed substantial Cr contaminations, surpassing by almost four and two times, respectively, the global average for fluvial sediments (90 pg g-l). This contamination was probably due to clandestine tanneries of that area. No high Cr contamination of sediments from the Mamona Rivulet in Ressaquinha (Fig. 2a) was observed. The levels found in these samples
Juiz de Fora 4 1 2 14 3 9
sites), 53 pg g-i
50.2 84.0 93.2 147 170
(Torres,
k * + f +
3 2 5 13 18
1992).
(Table 2) may indicate a scavenging effect of heavy metals discharged by local industries. On the other hand, the Cr waste output from the Santa Matilde tannery in Uba (Fig. 2b) was considerable. Sediments collected from the Rhine (the main river of Germany) have also shown high Cr levels, its contamination being attributed to tanneries and other industries near the Weschnitz River, one of its tributaries (Forstner and Wittmann, 1981). A similar study was reported for Skeleton Creek in the USA, where an average Cr concentration of 5.1 pg 8-l was observed (Namminga and Wilhm, 1977). On the other hand, the Cr contents of sediments from the Iraja River in Brazil ranged from 210 to 70 000 pg g-l. This river receives waste discharges from an electroplating industry (Pfeiffer et al., 1982). Metallic contamination has also been observed in fluvial sediments near smelteries in the State of Minas Gerais (Jordao et al., 1996). Sediment Enrichment Factors (SEF) were also investigated. They estimate the relative enrichment of trace metals by cultivation effects and express the ratio of the metal concentration in the sediment to another element of even distribution in the same environment. Finally, this ratio when compared with values from the same metal in the lithosphere defines the SEF (Fiirstner and Wittmann, 1981). Although Al is commonly chosen as a ‘conservative’ element, Brazilian oxisoils are commonly ‘enriched’ with it. For convenience
C.P. Jord2o
et
al.
/The
Science
qf the
cobalt was selected due to its even distribution in sediments and soils from the adjacent Vale do Ago. Sediment investigations from Dores de Campos showed a strong enrichment of Cr (SEF = 42) due to the waste discharges into the AGude Stream from both Sao Marcos and Arruda leather factories (Fig. Ic). Site 1 also showed a relatively strong enrichment (SEF = 5.01, probably due to other tannery discharges near the site. Riverains have reported 13 tanneries in the region, with most being clandestine and difficult to locate. The SEF values for Cr found in several lacustrine and marine environments range from 1.3 to 3.0 (Salomons and Fiirstner, 1984). Other patterns of heavily polluted rivers have also been documented. Thus, the SEF for Cr was 22 in Uba (site 31, whereas this element had an enrichment rating of 3.9 in Ipatinga (also at site 3). This site receives the waste discharges directly from the leather factories. In general, site 3 showed higher SEF values as compared with those of other sites. Tories (1992) found SEF values ranging from 2.2 to 7.2 for dredged sediments from the Paraibuna River, which traverses industrialized areas in the neighborhood of the study region. The Geoaccumulation Index (IEeo), which supplies a quantitative standard of metal pollution in aquatic sediments, was also examined using the following equation:
where C,, expresses the metal concentration of the element IZ and B, the geochemical background value. The factor of 1.5 accounts for possible variations of the background data due to lithogenic effects (Salomons and Fiirstner, 1984). The Bn value selected for this study was 26.3 pg g-r (obtained from the analysis of the sediment collected at the Espirito Santo Rivulet, Belmiro Braga). The geoaccumulation index of sediments consists of seven grades (O-6), i.e. from not polluted (value 0) to highly polluted (value 61, with the highest one reflecting a 100-fold enrichment of
Total Environment
207 (1997)
7
I-11
the background value. The Igeo values for the metals examined in this work are shown in Fig. 3. The Igeo for Cr attained a maximum value of 3 (moderately to heavily polluted) at site 3 in Ipatinga, while the other sites in this region were not polluted. The geoaccumulation indices resemble those of the Paraibuna River, which traverses industrialized areas in the neighborhood of the study region (Torres, 1992). The highest value (grade 6) was reached at site 3 in Dores de Campos. Chromium showed, in general, geoaccumulation indices rating 1 (non-polluted to moderately polluted) in Matias Barbosa and Ressaquinha. A similar result was found in the Elbe River in Germany (Salomons and Fbrstner, 1984). Table 3 lists vegetation genera collected in the sites (except Ipatinga and sites 7 and 8 in Uba).
Matias
Dores
Barbosa
de Campos
Ressaquinha
Juiz de Fora
2
Fig. 3. Geoaccumulation
ZZamplirTg
sites’
indices
for metals
6
in sediments.
7
8
C.P. JordZo
et al. /The
Science of the Total Environment
Data from the chemical analysis for the vegetation are shown in Table 4. Their levels relate to availability through HN03/HC10, digestion. Plants are important for metal concentration and availability for aquatic nutrition chains (Lacerda et al., 1979). The individual metal concentrations in living tissues are generally low (Jordao and Nickless, 1989) and must be maintained within narrow limits to secure optimum biological performances. Chromium as well as other metals are absorbed by roots and leaves and transported via the vascular system and may be stored and mobilized according to demand Wloway, 1993). Chromium contamination was noticed in all sites as compared with the normal concentration in plants (0.2-1.0 pg g-l), attaining the highest value in Dores de Campos (site 3) at the Acude Stream (Fig. lc), which itself receives waste waters from
Table 3 Vegetation Site No.
genera
from
various
sampling
sites
Barbosa
Dores
Brachiatia Brachiatia Paspalum Bra&aria Brachiaria
Site No.
concentration
in vegetation
de Campos
Cyperus Paspalum Paspalum TIpha Brachiatia Panicum
from
various
sampling
Ressaquinha
UbL
Juiz de Fora
Panicum Panicum Paspalum Pennisetim Panicum
Brachiaria Panicurn Panicum’ Commelina Brachiaria Brachiaria
Sorghum Panicum Brachiaria Brachiaria Brachiaria
sites ( pg g-r,
dry wt.)a,b,c
Location Matias
1 2 3 4 5 6
two tanneries (Sao Marcos and Arruda). The concentration at this site was 740 times above this control value. On the other hand, site 5 in I-lb6 also showed a high chromium concentration, with over 274 times the control value. The result of this site was consistent with its sediment amounts, i.e. 168 pg g-l. The vegetation analysed from Matias Barbosa showed chromium contamination ranging from 3.6 to 8.9 pg g-l, the average being still lower than those from other sites. This fact may be attributed to the closing down of the Matiense tannery. The relatively low Cr concentration found at site 3 of Ressaquinha was certainly due to the temporary shut-down of the Courugo tannery. These observations confirm the plant capacity to retain heavy metals. The vegetation from sites 3 to 6 at Ub6 also showed Cr contamination. It is reasonable to
Location Matias
Table 4 Chromium
207 (1997) l-11
3.6 + 4.1* 8.9 + 4.6 f 3.7 +
Barbosa 1.5 1.3 3.4 2.2 1.1
Dores 14.2 14.6 740 2.3 20.2 6.7
+ + * + + +
de Campos
Ressaquinha
ubl
3.4 5.8 105 0.2 5.4 2.7
9.4 24.8 21.2 15.7 21.5
5.4 6.7 18.7 56.7 274 41.4
aMean of three replicates i standard deviation. bNormal concentration of Cr in plants, 0.2-1.0 pg g-r (Allaway, 1968). “Value from a non-polluted region (Espirito Santa Rivulet in Belmiro Braga),
+ + f + f
0.6 3.5 5.7 5.6 2.3
3.5 pg g-r.
Juiz de Fora + f i + + &
0.6 2.2 3.6 7.4 72 4.8
11.5 14.7 25.4 7.4 8.2 -
f f + + f
0.7 1.0 0.7 0.8 0.3
C.P. JordGo et al. /The
Science
of the Total Environment
suppose that the contamination resulted from leather processing, being attributed to pollution from the Santa Matilde tannery. At the time of sample collection this factory manufactured only half of its daily capacity of 600 bovine skins, 80% of which were exported. Chromium, used as Cr(OH)SO, contains 25% Cr,O, and is sold as ‘Cromosol’. The cured hide also receives NaHCO, to enhance basic&y. Similarly, the Sao Marcos tannery in Dores de Campos employs a commercial product (Pancromo 13:13), delivered in containers of 145 kg each as a green solution. It is possible that cattle absorb chromium through grass consumption. Thus, local riverains attribute the death of cattle as well as birds to effluent discharges from the Courugo tannery. This tannery (now named White and Blue Indfistria e Comercio Ltd.), as mentioned earlier, has temporarily been shut-down until it has proven its ability to process wastes adequately. It is interesting to note that although a stimulatory effect of Cr in plants has been reported, it has not yet been established whether or not this element is essential (Alloway, 1993). The chromium concentration in seaweeds range from 0.3 to 3 ,ug g -’ (Fbrstner and Wittmann, 1981). The Cr concentration in grasses from the banks of the Piracicaba and Dote rivers in the Vale do AGO were above the average for plants (Jordao et al., 1996). Other workers (Lacerda et al., 1979) have reported that the grass Puspalum uaginatum, collected from the Iraj6 River in Brazil, was exposed to waste discharges from an electroplating factory. They found that Cr concentrations (expressed in pg g-l of ash contents) attained the values of 172.7, 74.2 and 779 in leaves, culms and roots, respectively. However, further studies of the same region showed Cr concentrations (expressed in pg g-r, dry weight base) of 16.8 and 7.6 in leaves and culms, respectively (Pfeiffer et al., 1982). In the present study, Cr concentrations varied from 2.3 to 740 pg g-l. Vegetation collected near the Real tannery (Fig. 2c, site 3) contained high Cr levels (25.4 pg g-l). The contamination was attributed to this tannery since other tanneries in this region had definitively been shut-down.
207 (1997)
9
l-11
Table 5 Chromium concentration in fish from various sampling sites ( pg g-l, wet wt.)a,b Site No.
Studied area
Fish species
Organ Visceral tissue
3 1 1 4 5 5
Ipatinga ub6 UbB Matias Barbosa Matias Barbosa Juiz de Fora
Oreochomis Cichlasoma Hypostomus Astyanm Astyanm Astyanax
15.2 + 0
2.1 + 0.9 5.7 + 2.3 2.6 + 0.3 7.3 + 2.6 0.9 + 0.2
Muscle 3.5 + 0.2 + 1.4 k 0.5 f 1.6 f 0.5 *
1.9 0.1 1.1 0.2 0.2 0.4
aMean of three replicates k standard deviation. bLegally permissible concentration, 0.1 pg g-’ (Pfeiffer et al., 1985).
Sediment and vegetation (Cyperus sp.) analysis from the unmineralized and non-industrialized region, the Belmiro Braga site (Tables 2 and 4, respectively), contained only low levels of Cr. Chromium may be found in geologic and lithogenic strata, but higher concentrations are attributed to anthropogenic activities. Chromium is essential for animals, being involved in glucose metabolism (Alloway, 19931, but heavy metals may accumulate in specific organs. A significant content in the tissues may indicate that its restraint capacity has been exceeded (Pereira, 1995). An evaluation of metal levels in fish may indicate environmental contamination, but these levels are usually low (Jordao et al., 1996). Thus, almost all heavy metals are absorbed by fish, but higher concentrations are found in polluted areas (MacCarthy and Ellis, 1991). Although the concentration of heavy metals in the muscle tissue of contaminated fish is often much lower than in other organs, the muscle contamination in fish must be considered in the investigation as it is the end consumer in the aquatic food chain. Consequently, the possible unfitness for human consumption from a toxicological point of view must be taken into account (Forstner and Wittmann, 1981). The data from fish samples are presented in Table 5. Since sufficient suitable material was not available, samples were collected only at a few sites. Chromium concentrations in fish that feeds
10
C.P. Jordcio et al. /The
Science of the Total Environment
on the bottom of its habitat (Nygostomus sp.> were higher than those found in Cichlasoma sp. specimens, angled in surface layers. The Cr concentrations in muscle tissues ranged from 0.2 to 3.5 Pug g-5 signifying that all samples were contaminated, since the allowed value for edible fish by Brazilian law is 0.1 pg g-r (Pfeiffer et al., 1985). These results may indicate Cr bioavailability in all studied sites. High Cr contamination has also been reported in Astyanax sp. from the Piracicaba River in the Vale do AGO ranging from 70 to 130 times the Brazilian Environment Standard (Pereira, 3995). The Poecilia reticulata species, a fish angled in the Iraji River, which transverses a highly polluted area in Brazil, showed an average concentration of 1.13 pg Cr g-r (Pfeiffer et al., 1982). In contrast, fish such as Mugil sp., Geophagus sp., Centropomus sp., Brevortia sp., Tilapia sp., Genidens sp. and Micropogonias sp., from the non-industrialized area of the Jacarepagua lagoons in Brazil, showed a low average of 0.08 pg g-r (Fernandes et al., 1994). Nevertheless, similar Cr concentrations in the fish studied in this work were found in other species, such as Mu@ sp.? Cynoscium sp., Micripogonias sp. and Haemulon sp. These fish were collected in a non-industrialized region, but under the influence of industrialized areas in Brazil (Pfeiffer et al., 1985). Thus, it is apparent that there is an exchange of Cr between biotic and abiotic compartments in the ecosystem studied. Almost all sites located down river from the tanneries showed enhanced Cr contamination. On the other hand, leather chippings disposed near a tannery in Uba, showed a high chromium level (3.8%). Thus, this element might lixiviate and contaminate the underground water. Because of environmental concerns, this kind of dreg would require severe control. Acknowledgements
Financial assistance by the Brazilian government (Conselho National de Desenvolvimento Cientifico e Tecnologico - CNPq) is gratefully acknowledged.
207 (1997)
l-11
References Agemian H, Chau ASY. An atomic absorption method for the determination of 20 elements in lake sediments after acid digestion. Anal Chim Acta 1975;80:61-66. Agudo EG. Guia de coleta e preserva+o de amostras de &gm Cetesb, Sao Paulo, 1987:150. Albasel N, Cottenie A. Heavy metal contamination near major highways, industrial and urban areas in Belgian grassland. Water Air Soil Pollut 1985;24:103-109. Allaway WH. Agronomic controls over the environmental cycling of trace elements. Adv Agron 1968;20:235-274. Alioway BJ. Heavy Metals in Soils. Great Britain: Blackie Academic, 1993:339. Alvarez VH, Melo JWV, Dias LE. Curso de fertilidade e manejo do solo. Module IV - Acidez do solo. Distrito Federal, Brasil: ABEAS/UFV, 1994:62. Fernandes HM, Bidone ED, Veiga LHS, Patchineelan SR. Heavy metal pollution assessment in the coastal lagoons of Jacarepagua. Rio de Janeiro, Brazil. Environ Pollut 1994;85:259-264. Forstner U, Wittmann GTW. Metal Pollution in the Aquatic Environment. Berlin: Springer-Verlag, 1981:486. Funda@o Estadual do Meio Ambiente. Controle de processes tecnicos e cientificos. Brasil: Belo Horizonte, 1994. Grozza G. Curticion de cuer-os y pieles: manual practice de1 curtidor. Barcelona: Sintes, 1984:256. Jardim WF. PoluiqCo aquatica: metais pesados, urn dano irreparavel. Rev Bras Tecnol 1983;14:41-45. Jordao CP, Nickless G. An evaluation of the ability of extractants to release heavy metals from alga and mollusc samples using a sequential extr-action procedure. Environ Techno1 Lett 1989;10:445-451. Jordlo CP, Pereira JC, Bnme W, Pereira JL, Braathen PC. Heavy metal dispersion from industrial wastes in the Vale do Ago, Minas Gerais, Brazil. Environ Technol 1996;17:489-500. Lacerda LD, Pfeiffer WC, Fiszman M. 0 papel de Paspalum vaginaturn na disponibilidade de cromo para as cadeias alimentares estuarinas. Rev Bras Biol 1979;39:985-989. Malm 0, Pfeiffer WC, Fiszman M, Azcue JM. Heavy metal concentrations and availability in the bottom sediments of the Paraiba do Sul-Guandu River system, RJ, Brazil. Environ Technol Lett 1989;10:675-680. MacCarthy HT, Ellis PC. Comparison of microwave digestion with conventional wet ashing and dry ashing digestion for analysis of cadmium, copper, and zinc in shellfish by flame atomic absorption spectroscopy. J Assoc Off Anal Chem 1991.;74:566-569. McGrath SP, Smith S. Chromium and nickel, In: Alloway BJ, editor. Heavy Metals in Soils. Great Britain: Blackie Academic, 1993:125-146. Namminga H, Wilhm J. Heavy metals in water, sediments, and chironomids. J Water Pollut Contr 1977;49:1725-1731. Pereira JC. Ava1iaQ.o da contamina@o do meio ambiente por metais pesados na regiao do Vale do Ago (MG). Departa-
C.P. Jordso
et al. /The
Science of the Total Environment
mento de Quimica. Universidade Federal de Visosa, Tese de Mestrado, 1995:117. Perez G. Curtume aumenta a agonia dos rios mineiros. 0 Estado de Minas, 02 de Julho. Minas Gerais, Brasil, 1991. Pfeiffer WC, Fiszman M, Lacerda LD, Weerelt MV. Chromium in water, suspended particles, sediments and biota in the Iraj& river estuary. Environ Pollut 1982;4:193-205. Pfeiffer WC, Lacerda LD, Fiszman M, Lima NRW. Metais pesados em pescado da Baia de Sepetiba, Estado do Rio de Janeiro RJ. Ci Cult 1985;37:297-302.
207 (1997) 1 -II
11
Sala LF, Rizzoto A, Frascaroli MI, Palopoli CM, Signorella SR. Contamination ambiental por el metal de transition cromo. Estamos frente a un serio problema ecokjgico?. Quim Nova 1995;18:468-474. Salomons W, Forstner U. Metals in the Hydrocycle. New York: Springer-Verlag, 1984:349. Torres JPM. Ocorr&ncia e distribui@o de metais pesados no Rio Paraibuna, Juiz de Fora, MG. Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Tese de Mestrado, 1992114.
of the Total
Environment
207 (1997)
l-11
Chromium contamination in sediment, vegetation and fish caused by tanneries in the State of Minas Gerais, Brazil C.P. Jord5o” , J.L. Pereira, G.N. Jham Departamento
de Quimica,
Uliversidade Received
Federal
12 May
de EGosa 36571-000,
1997; accepted
I/isosa, Minas
Gerais, Brazil
30 July 1997
Abstract
In order to evaluatethe chromiumcontaminationfrom tannery dischargesinto rivers in the State of Minas Gerais, Brazil, samplesof fluvial sediment,vegetation and fish were collected and submitted to chemical analysis.The chromium content in the sampleswasmeasuredby atomic absorptionspectrophotometry.Metal inputs were related to effluent dischargesinto the rivers. High concentrationsof chromiumwere found in sampleswhen comparedwith controls. Sedimentinvestigationsindicated strong enrichment and high geoaccumulationindices,while chromium concentrations in the analyzed vegetation were higher than those normally found in these materials. Chromium levels in fish exceeded35 times the Brazilian recommendationvalue for human intake. 0 1997Elsevier Science B.V.
1. Introduction Aquatic contamination by heavy metals is very harmful since these elements are not degradable in the environment and may accumulate in living organisms (Jardim, 1983). Several studies on the pernicious effects of heavy metals in organisms, e.g. chromium and its carcinogenic compounds have been reported (Sala et al., 1995). Chromium is used in substantial amounts by the leather tanning industry (FGrstner and Wittmann, 1981). It cannot be predicted on how long the environment can integrate toxic wastes. Therefore, con-
* Corresponding
author.
004%9697/97/$17.00 0 1997 Elsevier PZZ SOO48-9697(97)00232-5
Science
B.V. All rights
centrations of heavy metals, including chromium, must be determined in order to evaluate their environmental effects. Several tanneries operate in the State of Minas Gerais and produce approximately 10% of Brazilian leather (Perez, 1991). Approximately 75 of them are legally registered, but most of them discharge their wastes directly into the rivers without any previous treatment (Fundac$o Estadual do Meio Ambiente, 1994). It is a well-known fact that chromium is essential for leather quality, such as strength, elasticity and thickness (Grozza, 1984), however, no determination of heavy metal concentrations have been carried out in the rivers near tanneries in the State of Minas Gerais. reserved.
2
C.P. Jordrio
et al. /The
Science of the Total Environment
The knowledge of the metal concentrations in river sediments is important from both a geochemical and an environmental view point (Agemian and Chau, 1975). Fluvial sediments constitute a stabilization factor between soluble and insoluble pollutants within aquatic environments, due to their presence over a long period of time in rivers and their capacity to neutralize drained off discharges (Agudo, 1987). High levels of metals in soils do not necessarily reflect elevated doses in plants since other factors, such as the pH, cation exchange capacity, organic matter and humidity may also influence their uptake (Albasel and Cottenie, 1985). Thus, chromium contents in leaves show little relationship with the overall concentrations of Cr in soils (McGrath and Smith, 1993). However, waste spillage on land may contaminate the underground waters. Fishes are commonly used as an indicator for pollution control in aquatic environments. Relatively low amounts of Cr, Pb and Zn have been reported in fish when compared to those of abiotic sites (Fernandes et al., 1994). Thus, it is reasonable to assume that abiotic niches of ecosystems are enhanced by high heavy metal levels (Pfeiffer et al., 1985). This does not mean, however, that pollutants are innocuous through fish consumption. No reliable values of Cr concentrations are available in fluvial sediment, vegetation and fish from waste discharge of tanneries in the State of Minas Gerais. Thus, the purpose of this article is to study the distribution of this element in the river systems near tanneries in Brazil. 2. Material
and methods
South-eastern regions of the State of Minas Gerais were studied since leather factories discharge waste waters into the local rivers without any previous treatment. The sampling locations are shown in Figs. 1 and 2. Samples from an uncontaminated spring (Espirito Santo Rivulet in Belmiro Braga) close to the studied area were investigated to get regional background values. Sediment, vegetation and fish samples were obtained in the dry season at sites up- and down-river with respect to tanneries and kept at 4°C until analysis.
207 (1997)
l-11
Surface sediments were scooped at river-shores, excess surface water was skimmed off and sediments placed into plastic bags. The samples were oven-dried at 105°C and passed through an 80 mesh sieve. Another set of samples were ovendried at 60°C for 48 h and passed through a 9 mesh sieve for pH measurements. For chromium determination, 1 g of the sediment was first digested with 10 ml of concentrated HNO, solution to near dryness; aliquots of 10 ml of concentrated HF and 2 ml of concentrated HClO, solutions were added and the mixture was evaporated to near dryness. Finally, the residue was dissolved in 2 ml of 12 N HCl and diluted to 25 ml with deionised water. The pH of sediment was measured in both 1 M MC1 solution and distilled water (solid/solution ratio = 1:2.5). Plants (Paspalum sp., Panicum sp., Brachiaiia sp., Typha sp., Ciperacia sp., Commelina sp. and Sorghum sp.) were cut above the river water level and washed before trace element analysis. The clippings were stored in acid-washed plastic bags, transported to the laboratory at 5°C thawed and sectioned in pieces. The leaves were dried at 105°C for 24 h and a 10-g portion was digested at room temperature with 10 ml of concentrated HNO, solution. A second portion of HNO, (20 ml) was added and the mixture evaporated at 150°C. Finally, solutions of concentrated HNO, (10 ml) and HClO, (5 ml) were added and the mixture was evaporated to near dryness. The resultant solution was diluted with deionised water to 25 ml. Metal concentrations in decapitated and eviscerated fishes were determined in visceral mass and muscle tissues of Oreochomis sp., Astyanax sp., Cichlasoma sp. and Hypostomus sp. Fish were angled only at a few sites since sufficient suitable material was not available for analyses. The fish weight varied between 14.4 and 66.8 g (8.9-19 cm in length) and the heads and tails were discarded. Samples were oven-dried at 105°C for 48 h and ground in a ceramic mortar. Portions of visceral mass (1 g) and muscle tissue (5 g) were individually digested at 150°C with 20 ml of concentrated HNO, solution and the mixture evaporated to near dryness. The samples were further digested at 150°C with 10 ml of concentrated HNO, and 5
C.P. Jordiio et al. /The Science of the Total Environment 207 (1997) I-11
3
(bl
(0)
O-SAMPLING
LOCLTION
IPATINGA VALE
DO
AGO
*\usr \
O-S4MpLING
LOC4TION
cl-T4WERY 0
BT-GAl4NO
0
JW-JOSg
0
47-
0
SW-sio -.-
Fig. 1. study
areas: (a) Ipatinga;
(b) Matias
ml of 30% (w/v) H,O,, and the mixture evaporated to near dryness. When necessary, due to the high fat content of fish, the sampleswere also subsequently digested with a solution of concentrated HNO, (5 ml) and HClO, (5 ml) and diluted with deionised water to 25 ml. Leather chippings were also collected in the tannery located in Uba. The sampleswere ovendried at 60°C for 24 h. Subsamples of 1 g each
Barbosa;
D4
(c) Dores
HARIOUINHA
ARRVOA HARCOS MUNKIP4L
OlSTRlCT
de Campos.
were first digested with solutions of concentrated HNO, and HCl (10 ml each). To the mixtures were added solutions of concentrated HNO, (10 ml) and HClO, (5 ml) and diluted with deionised water to 25 ml. Metal concentration was measured with a Carl Zeiss JENA, model AAS atomic absorption spectrophotometer by direct aspiration of the solution into a nitrous oxide-acetylene flame.
4
C.P. Jodio
et al. / The Science of the Total Environment
207 (1997) l-11
I
I
JUiZ
DE FORA
I
Fig. 2. Study areas: (a) Ressaquinha; (b) UbB; (c) Juiz de Fora.
C.P. Jordiio
et al. /The
Science
of the
Total Environment
Certified analytical grade reagents were used for analysis. Blanks were run through all experiments to control any contamination. 3. Results
and discussion
pH values
Site No.
pH in distilled 1 2 3 4 5 6
from
various
sampling
1-11
5
Vale do Ago (literally ‘Steel Valley’) in the State of Minas Gerais (Jordgo et al., 1996). The mean chromium concentrations of three replicates in the sediments of each sampling station are presented in Table 2. It was observed, in general, that the Cr concentration in site 3 of each region (near the waste discharge points) is higher than those found from sites 1 or 2 (upriver with the tanneries). For instance, the contamination of the sediment collected at site 3 in Ipanema Stream was attributed to the Kapard tannery of Ipatinga, since its waste discharge is located at a distance of only 50 m from this site (Fig. la). The sediment samples, gathered in the dry season showed Cr concentrations ranging from 14.2 to 266 pg 8-l in Ipatinga. High contamination of sediments from the Piracicaba River in Ipatinga collected in the dry season has also been observed. Thus, the Cr levels in the rainy season showed less contamination, since a smaller volume would obviously exhibit a higher concentration of pollutants (Jordso et al., 1996). A uniform distribution of Cr concentrations in sediment samples along the Paraibuna River in Matias Barbosa was observed (Fig. lb). The maximum value was found in site 3 and was approximately twice as high as that of the control area
The pH of the sediments measured both in KC1 solution and distilled water ranged from 3.7 to 7.5 (Table 1). Addition of KC1 to the solution maintains its ionic strength and reduces the pH change due to dilution (Alvarez et al., 1994). In general, the pH measured in KC1 solutions gave lower values than those in distilled water. This seems reasonable since a higher proton content is to be expected from KCl-amended sediments. The low pH values of some sites suggests a high negative charge on the clay component. Sample site 6 in Ipatinga (Ipanema Stream) showed a considerably higher pH value (7.5) than the others. This may be explained by assuming that the sediment collected at this site had a high dredged sand content. Sediment pH values were similar to those of an uncontaminated area (Espirito Santo Rivulet in Belmiro Braga), i.e. 4.5 in H,O and 3.9 in KCl. Values of pH ranging from 4.3 to 6.4 have been reported for sediments from the Piracicaba and Dote rivers, within the
Table 1 Sediment
207 (1997)
sites
Location Ipatinga
Matias
6.7 3.8 6.6 4.5 6.3 7.5
5.5 5.4 5.6 5.9 5.4 -
4.8 3.7 6.4 4.2 6.1 7.3
5.5 5.0 5.0 5.1 4.8
Barbosa
Dores
de Campos
Ressaquinha
Uba
Juiz de Flora
4.1 5.2 5.4 5.8 5.4 5.6
5.4 5.0 5.1 4.9 3.7
4.5 5.3 5.2 4.9 4.9 4.7
5.5 6.9 7.2 6.9 7.1 -
4.0 4.5 5.0 4.3 4.7 4.3
4.3 4.5 4.5 4.8 3.7
4.1 4.7 5.1 4.9 4.8 4.3
4.3 5.4 6.5 5.0 5.0
water
pH in 1 M KC1 solution 1 2 3 4 5 6
6
C.P. Jordiio
Table 2 Chromium Site No.
concentration
“Mean bGlobal ‘Value dValue
from
various
Science of the Total Environment
sampling
sites ( pg g-l,
207 (1997) 1-11
dry wt.)“* bZ ‘. d
Location Ipatinga
1 2 3 4 5 6 7
in sediments
et al. /The
19.0 14.2 266 37.3 24.1 57.8
+ + + & i +
9 5 95 17 2 2
Matias
Barbosa
80.0 60.1 93.0 87.9 86.2
12 20 3 16 9
+ f i + k
Dores
de Campos
340 + 31.2 k 2878 + 156 i 131* 897 +
7 21 78 12 28 0.3
Ressaquinha
Ub6
70.1 87.0 98.5 74.0 43.9
75.0 f 68.9 f 1531+ 334 + 168 * 243 + 120*4
f + + + +
7 16 3 14 5
of three replicates f standard deviation. average value for fluvial sediments, 90 pg 8-l (Maim et al., 1989). from a non-polluted region (Espirito Santo Rivulet in Belmiro Braga), 26.3 pg g-i. from a non-industrialized region (Grande, Negro and Preto rivers, near the studied
(53 pg g-i). However, the Cr concentration found at site 4 was three times the value (26.3 pg g-l) obtained from the sediment of the non-mineralized nor polluted region of Belmiro Braga (Table 2). Although the Matiense tannery had been shut-down at the time of sample collection, the high Cr concentration might be attributed to the metal retention capacity of sediments, as well as to the high industrialization of the region. A comparison of Cr concentrations for fluvial sediments with those of non-industrialized areas near the studied sites, showed Cr inputs from several tanneries (Table 2). Thus, 79% of samples showed Cr concentrations above the mean value (53 Fg g-l> found in those areas (Torres, 1992). The dark sediment from site 3 of Dores de Campos (Fig. lc) was very contaminated, its Cr concentration being 54 times higher than the control value. This result reveals that the Cr level at site 3 exceeded those found in the vegetation and fish samples analysed. Nevertheless, sediment samples collected upriver with the tanneries at both sites 1 (AGude Stream) and 4 (Patusca Stream) showed substantial Cr contaminations, surpassing by almost four and two times, respectively, the global average for fluvial sediments (90 pg g-l). This contamination was probably due to clandestine tanneries of that area. No high Cr contamination of sediments from the Mamona Rivulet in Ressaquinha (Fig. 2a) was observed. The levels found in these samples
Juiz de Fora 4 1 2 14 3 9
sites), 53 pg g-i
50.2 84.0 93.2 147 170
(Torres,
k * + f +
3 2 5 13 18
1992).
(Table 2) may indicate a scavenging effect of heavy metals discharged by local industries. On the other hand, the Cr waste output from the Santa Matilde tannery in Uba (Fig. 2b) was considerable. Sediments collected from the Rhine (the main river of Germany) have also shown high Cr levels, its contamination being attributed to tanneries and other industries near the Weschnitz River, one of its tributaries (Forstner and Wittmann, 1981). A similar study was reported for Skeleton Creek in the USA, where an average Cr concentration of 5.1 pg 8-l was observed (Namminga and Wilhm, 1977). On the other hand, the Cr contents of sediments from the Iraja River in Brazil ranged from 210 to 70 000 pg g-l. This river receives waste discharges from an electroplating industry (Pfeiffer et al., 1982). Metallic contamination has also been observed in fluvial sediments near smelteries in the State of Minas Gerais (Jordao et al., 1996). Sediment Enrichment Factors (SEF) were also investigated. They estimate the relative enrichment of trace metals by cultivation effects and express the ratio of the metal concentration in the sediment to another element of even distribution in the same environment. Finally, this ratio when compared with values from the same metal in the lithosphere defines the SEF (Fiirstner and Wittmann, 1981). Although Al is commonly chosen as a ‘conservative’ element, Brazilian oxisoils are commonly ‘enriched’ with it. For convenience
C.P. Jord2o
et
al.
/The
Science
qf the
cobalt was selected due to its even distribution in sediments and soils from the adjacent Vale do Ago. Sediment investigations from Dores de Campos showed a strong enrichment of Cr (SEF = 42) due to the waste discharges into the AGude Stream from both Sao Marcos and Arruda leather factories (Fig. Ic). Site 1 also showed a relatively strong enrichment (SEF = 5.01, probably due to other tannery discharges near the site. Riverains have reported 13 tanneries in the region, with most being clandestine and difficult to locate. The SEF values for Cr found in several lacustrine and marine environments range from 1.3 to 3.0 (Salomons and Fiirstner, 1984). Other patterns of heavily polluted rivers have also been documented. Thus, the SEF for Cr was 22 in Uba (site 31, whereas this element had an enrichment rating of 3.9 in Ipatinga (also at site 3). This site receives the waste discharges directly from the leather factories. In general, site 3 showed higher SEF values as compared with those of other sites. Tories (1992) found SEF values ranging from 2.2 to 7.2 for dredged sediments from the Paraibuna River, which traverses industrialized areas in the neighborhood of the study region. The Geoaccumulation Index (IEeo), which supplies a quantitative standard of metal pollution in aquatic sediments, was also examined using the following equation:
where C,, expresses the metal concentration of the element IZ and B, the geochemical background value. The factor of 1.5 accounts for possible variations of the background data due to lithogenic effects (Salomons and Fiirstner, 1984). The Bn value selected for this study was 26.3 pg g-r (obtained from the analysis of the sediment collected at the Espirito Santo Rivulet, Belmiro Braga). The geoaccumulation index of sediments consists of seven grades (O-6), i.e. from not polluted (value 0) to highly polluted (value 61, with the highest one reflecting a 100-fold enrichment of
Total Environment
207 (1997)
7
I-11
the background value. The Igeo values for the metals examined in this work are shown in Fig. 3. The Igeo for Cr attained a maximum value of 3 (moderately to heavily polluted) at site 3 in Ipatinga, while the other sites in this region were not polluted. The geoaccumulation indices resemble those of the Paraibuna River, which traverses industrialized areas in the neighborhood of the study region (Torres, 1992). The highest value (grade 6) was reached at site 3 in Dores de Campos. Chromium showed, in general, geoaccumulation indices rating 1 (non-polluted to moderately polluted) in Matias Barbosa and Ressaquinha. A similar result was found in the Elbe River in Germany (Salomons and Fbrstner, 1984). Table 3 lists vegetation genera collected in the sites (except Ipatinga and sites 7 and 8 in Uba).
Matias
Dores
Barbosa
de Campos
Ressaquinha
Juiz de Fora
2
Fig. 3. Geoaccumulation
ZZamplirTg
sites’
indices
for metals
6
in sediments.
7
8
C.P. JordZo
et al. /The
Science of the Total Environment
Data from the chemical analysis for the vegetation are shown in Table 4. Their levels relate to availability through HN03/HC10, digestion. Plants are important for metal concentration and availability for aquatic nutrition chains (Lacerda et al., 1979). The individual metal concentrations in living tissues are generally low (Jordao and Nickless, 1989) and must be maintained within narrow limits to secure optimum biological performances. Chromium as well as other metals are absorbed by roots and leaves and transported via the vascular system and may be stored and mobilized according to demand Wloway, 1993). Chromium contamination was noticed in all sites as compared with the normal concentration in plants (0.2-1.0 pg g-l), attaining the highest value in Dores de Campos (site 3) at the Acude Stream (Fig. lc), which itself receives waste waters from
Table 3 Vegetation Site No.
genera
from
various
sampling
sites
Barbosa
Dores
Brachiatia Brachiatia Paspalum Bra&aria Brachiaria
Site No.
concentration
in vegetation
de Campos
Cyperus Paspalum Paspalum TIpha Brachiatia Panicum
from
various
sampling
Ressaquinha
UbL
Juiz de Fora
Panicum Panicum Paspalum Pennisetim Panicum
Brachiaria Panicurn Panicum’ Commelina Brachiaria Brachiaria
Sorghum Panicum Brachiaria Brachiaria Brachiaria
sites ( pg g-r,
dry wt.)a,b,c
Location Matias
1 2 3 4 5 6
two tanneries (Sao Marcos and Arruda). The concentration at this site was 740 times above this control value. On the other hand, site 5 in I-lb6 also showed a high chromium concentration, with over 274 times the control value. The result of this site was consistent with its sediment amounts, i.e. 168 pg g-l. The vegetation analysed from Matias Barbosa showed chromium contamination ranging from 3.6 to 8.9 pg g-l, the average being still lower than those from other sites. This fact may be attributed to the closing down of the Matiense tannery. The relatively low Cr concentration found at site 3 of Ressaquinha was certainly due to the temporary shut-down of the Courugo tannery. These observations confirm the plant capacity to retain heavy metals. The vegetation from sites 3 to 6 at Ub6 also showed Cr contamination. It is reasonable to
Location Matias
Table 4 Chromium
207 (1997) l-11
3.6 + 4.1* 8.9 + 4.6 f 3.7 +
Barbosa 1.5 1.3 3.4 2.2 1.1
Dores 14.2 14.6 740 2.3 20.2 6.7
+ + * + + +
de Campos
Ressaquinha
ubl
3.4 5.8 105 0.2 5.4 2.7
9.4 24.8 21.2 15.7 21.5
5.4 6.7 18.7 56.7 274 41.4
aMean of three replicates i standard deviation. bNormal concentration of Cr in plants, 0.2-1.0 pg g-r (Allaway, 1968). “Value from a non-polluted region (Espirito Santa Rivulet in Belmiro Braga),
+ + f + f
0.6 3.5 5.7 5.6 2.3
3.5 pg g-r.
Juiz de Fora + f i + + &
0.6 2.2 3.6 7.4 72 4.8
11.5 14.7 25.4 7.4 8.2 -
f f + + f
0.7 1.0 0.7 0.8 0.3
C.P. JordGo et al. /The
Science
of the Total Environment
suppose that the contamination resulted from leather processing, being attributed to pollution from the Santa Matilde tannery. At the time of sample collection this factory manufactured only half of its daily capacity of 600 bovine skins, 80% of which were exported. Chromium, used as Cr(OH)SO, contains 25% Cr,O, and is sold as ‘Cromosol’. The cured hide also receives NaHCO, to enhance basic&y. Similarly, the Sao Marcos tannery in Dores de Campos employs a commercial product (Pancromo 13:13), delivered in containers of 145 kg each as a green solution. It is possible that cattle absorb chromium through grass consumption. Thus, local riverains attribute the death of cattle as well as birds to effluent discharges from the Courugo tannery. This tannery (now named White and Blue Indfistria e Comercio Ltd.), as mentioned earlier, has temporarily been shut-down until it has proven its ability to process wastes adequately. It is interesting to note that although a stimulatory effect of Cr in plants has been reported, it has not yet been established whether or not this element is essential (Alloway, 1993). The chromium concentration in seaweeds range from 0.3 to 3 ,ug g -’ (Fbrstner and Wittmann, 1981). The Cr concentration in grasses from the banks of the Piracicaba and Dote rivers in the Vale do AGO were above the average for plants (Jordao et al., 1996). Other workers (Lacerda et al., 1979) have reported that the grass Puspalum uaginatum, collected from the Iraj6 River in Brazil, was exposed to waste discharges from an electroplating factory. They found that Cr concentrations (expressed in pg g-l of ash contents) attained the values of 172.7, 74.2 and 779 in leaves, culms and roots, respectively. However, further studies of the same region showed Cr concentrations (expressed in pg g-r, dry weight base) of 16.8 and 7.6 in leaves and culms, respectively (Pfeiffer et al., 1982). In the present study, Cr concentrations varied from 2.3 to 740 pg g-l. Vegetation collected near the Real tannery (Fig. 2c, site 3) contained high Cr levels (25.4 pg g-l). The contamination was attributed to this tannery since other tanneries in this region had definitively been shut-down.
207 (1997)
9
l-11
Table 5 Chromium concentration in fish from various sampling sites ( pg g-l, wet wt.)a,b Site No.
Studied area
Fish species
Organ Visceral tissue
3 1 1 4 5 5
Ipatinga ub6 UbB Matias Barbosa Matias Barbosa Juiz de Fora
Oreochomis Cichlasoma Hypostomus Astyanm Astyanm Astyanax
15.2 + 0
2.1 + 0.9 5.7 + 2.3 2.6 + 0.3 7.3 + 2.6 0.9 + 0.2
Muscle 3.5 + 0.2 + 1.4 k 0.5 f 1.6 f 0.5 *
1.9 0.1 1.1 0.2 0.2 0.4
aMean of three replicates k standard deviation. bLegally permissible concentration, 0.1 pg g-’ (Pfeiffer et al., 1985).
Sediment and vegetation (Cyperus sp.) analysis from the unmineralized and non-industrialized region, the Belmiro Braga site (Tables 2 and 4, respectively), contained only low levels of Cr. Chromium may be found in geologic and lithogenic strata, but higher concentrations are attributed to anthropogenic activities. Chromium is essential for animals, being involved in glucose metabolism (Alloway, 19931, but heavy metals may accumulate in specific organs. A significant content in the tissues may indicate that its restraint capacity has been exceeded (Pereira, 1995). An evaluation of metal levels in fish may indicate environmental contamination, but these levels are usually low (Jordao et al., 1996). Thus, almost all heavy metals are absorbed by fish, but higher concentrations are found in polluted areas (MacCarthy and Ellis, 1991). Although the concentration of heavy metals in the muscle tissue of contaminated fish is often much lower than in other organs, the muscle contamination in fish must be considered in the investigation as it is the end consumer in the aquatic food chain. Consequently, the possible unfitness for human consumption from a toxicological point of view must be taken into account (Forstner and Wittmann, 1981). The data from fish samples are presented in Table 5. Since sufficient suitable material was not available, samples were collected only at a few sites. Chromium concentrations in fish that feeds
10
C.P. Jordcio et al. /The
Science of the Total Environment
on the bottom of its habitat (Nygostomus sp.> were higher than those found in Cichlasoma sp. specimens, angled in surface layers. The Cr concentrations in muscle tissues ranged from 0.2 to 3.5 Pug g-5 signifying that all samples were contaminated, since the allowed value for edible fish by Brazilian law is 0.1 pg g-r (Pfeiffer et al., 1985). These results may indicate Cr bioavailability in all studied sites. High Cr contamination has also been reported in Astyanax sp. from the Piracicaba River in the Vale do AGO ranging from 70 to 130 times the Brazilian Environment Standard (Pereira, 3995). The Poecilia reticulata species, a fish angled in the Iraji River, which transverses a highly polluted area in Brazil, showed an average concentration of 1.13 pg Cr g-r (Pfeiffer et al., 1982). In contrast, fish such as Mugil sp., Geophagus sp., Centropomus sp., Brevortia sp., Tilapia sp., Genidens sp. and Micropogonias sp., from the non-industrialized area of the Jacarepagua lagoons in Brazil, showed a low average of 0.08 pg g-r (Fernandes et al., 1994). Nevertheless, similar Cr concentrations in the fish studied in this work were found in other species, such as Mu@ sp.? Cynoscium sp., Micripogonias sp. and Haemulon sp. These fish were collected in a non-industrialized region, but under the influence of industrialized areas in Brazil (Pfeiffer et al., 1985). Thus, it is apparent that there is an exchange of Cr between biotic and abiotic compartments in the ecosystem studied. Almost all sites located down river from the tanneries showed enhanced Cr contamination. On the other hand, leather chippings disposed near a tannery in Uba, showed a high chromium level (3.8%). Thus, this element might lixiviate and contaminate the underground water. Because of environmental concerns, this kind of dreg would require severe control. Acknowledgements
Financial assistance by the Brazilian government (Conselho National de Desenvolvimento Cientifico e Tecnologico - CNPq) is gratefully acknowledged.
207 (1997)
l-11
References Agemian H, Chau ASY. An atomic absorption method for the determination of 20 elements in lake sediments after acid digestion. Anal Chim Acta 1975;80:61-66. Agudo EG. Guia de coleta e preserva+o de amostras de &gm Cetesb, Sao Paulo, 1987:150. Albasel N, Cottenie A. Heavy metal contamination near major highways, industrial and urban areas in Belgian grassland. Water Air Soil Pollut 1985;24:103-109. Allaway WH. Agronomic controls over the environmental cycling of trace elements. Adv Agron 1968;20:235-274. Alioway BJ. Heavy Metals in Soils. Great Britain: Blackie Academic, 1993:339. Alvarez VH, Melo JWV, Dias LE. Curso de fertilidade e manejo do solo. Module IV - Acidez do solo. Distrito Federal, Brasil: ABEAS/UFV, 1994:62. Fernandes HM, Bidone ED, Veiga LHS, Patchineelan SR. Heavy metal pollution assessment in the coastal lagoons of Jacarepagua. Rio de Janeiro, Brazil. Environ Pollut 1994;85:259-264. Forstner U, Wittmann GTW. Metal Pollution in the Aquatic Environment. Berlin: Springer-Verlag, 1981:486. Funda@o Estadual do Meio Ambiente. Controle de processes tecnicos e cientificos. Brasil: Belo Horizonte, 1994. Grozza G. Curticion de cuer-os y pieles: manual practice de1 curtidor. Barcelona: Sintes, 1984:256. Jardim WF. PoluiqCo aquatica: metais pesados, urn dano irreparavel. Rev Bras Tecnol 1983;14:41-45. Jordao CP, Nickless G. An evaluation of the ability of extractants to release heavy metals from alga and mollusc samples using a sequential extr-action procedure. Environ Techno1 Lett 1989;10:445-451. Jordlo CP, Pereira JC, Bnme W, Pereira JL, Braathen PC. Heavy metal dispersion from industrial wastes in the Vale do Ago, Minas Gerais, Brazil. Environ Technol 1996;17:489-500. Lacerda LD, Pfeiffer WC, Fiszman M. 0 papel de Paspalum vaginaturn na disponibilidade de cromo para as cadeias alimentares estuarinas. Rev Bras Biol 1979;39:985-989. Malm 0, Pfeiffer WC, Fiszman M, Azcue JM. Heavy metal concentrations and availability in the bottom sediments of the Paraiba do Sul-Guandu River system, RJ, Brazil. Environ Technol Lett 1989;10:675-680. MacCarthy HT, Ellis PC. Comparison of microwave digestion with conventional wet ashing and dry ashing digestion for analysis of cadmium, copper, and zinc in shellfish by flame atomic absorption spectroscopy. J Assoc Off Anal Chem 1991.;74:566-569. McGrath SP, Smith S. Chromium and nickel, In: Alloway BJ, editor. Heavy Metals in Soils. Great Britain: Blackie Academic, 1993:125-146. Namminga H, Wilhm J. Heavy metals in water, sediments, and chironomids. J Water Pollut Contr 1977;49:1725-1731. Pereira JC. Ava1iaQ.o da contamina@o do meio ambiente por metais pesados na regiao do Vale do Ago (MG). Departa-
C.P. Jordso
et al. /The
Science of the Total Environment
mento de Quimica. Universidade Federal de Visosa, Tese de Mestrado, 1995:117. Perez G. Curtume aumenta a agonia dos rios mineiros. 0 Estado de Minas, 02 de Julho. Minas Gerais, Brasil, 1991. Pfeiffer WC, Fiszman M, Lacerda LD, Weerelt MV. Chromium in water, suspended particles, sediments and biota in the Iraj& river estuary. Environ Pollut 1982;4:193-205. Pfeiffer WC, Lacerda LD, Fiszman M, Lima NRW. Metais pesados em pescado da Baia de Sepetiba, Estado do Rio de Janeiro RJ. Ci Cult 1985;37:297-302.
207 (1997) 1 -II
11
Sala LF, Rizzoto A, Frascaroli MI, Palopoli CM, Signorella SR. Contamination ambiental por el metal de transition cromo. Estamos frente a un serio problema ecokjgico?. Quim Nova 1995;18:468-474. Salomons W, Forstner U. Metals in the Hydrocycle. New York: Springer-Verlag, 1984:349. Torres JPM. Ocorr&ncia e distribui@o de metais pesados no Rio Paraibuna, Juiz de Fora, MG. Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Tese de Mestrado, 1992114.