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To whom correspondence may be addressed. Fax: (#39)-081-2296625.

E-mail: [email protected].

Ecotoxicology and Environmental Safety 51, 28}34 (2002)

Environmental Research, Section B

doi:10.1006/eesa.2001.2114, available online at http://www.idealibrary.com on

Toxicity of Bauxite Manufacturing By-products in Sea Urchin Embryos

Giovanni Pagano,* SuKreyya Merii,- Antonella De Biase,* Mario laccarino,* Domenico Petruzzelli,?

Olcay TuKnay,- and Michel WarnauA

*Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione Pascale, I-80131 Naples, Italy; -Istanbul Technical University,

Environmental Engineering Department, Maslak 80600 Istanbul, Turkey; ?Department of Civil and Environmental Engineering,

Polytechnic University of Bari, 1-70125 Bari, Italy; and AInternational Atomic Energy Agency, Marine Environment Laboratory,

MC-98012 Monaco

Received January 18, 2001

By-products from a bauxite manufacturing plant located inSeydis

:

ehir, Turkey, were investigated for their composition and

any toxicity to sea urchin embryogenesis. Samples from threeother bauxite plants located in France, Greece, and Italy were

simultaneously tested for toxicity in sea urchin embryos. Sam-

ples included sludge and solid residues in the plant and sedimentand water columns from two holding ponds (red sludge or

cryolite residues). Samples were analyzed for their inorganiccontent by inductively coupled plasma optical emission spectro-

scopy (ICP-OES). Analyses were carried out either followingstrong acid extraction or after release of soluble components

from seawater-suspended pellets. Toxicity was tested by seaurchin bioassays, to evaluate the following endpoints: (a) acute

and/or developmental toxicity, (b) changes in fertilization suc-cess, and (c) transmissible damage from sperm to o4spring. The

results revealed the following: (1) inorganic analysis, followingstrong acid extraction, showed a prevalence of Al and Fe; (2)

seawater release of soluble contaminants was con5ned to Fe andMn, whereas Al levels were not changed by suspending increasingsample amounts in seawater; (3) the most severe toxicity to sea

urchin embryos was exerted by a 2% water column from the redsludge holding pond and by soil and sludge collected near the

plant reactor; (4) sludge supernatant was the most toxic sample

to sperm and o4spring. The data showed a prevailing associationof free Fe (and possibly Mn) levels with Seydis

:ehir sample

toxicity. The water column of the red sludge holding pond showedboth excess levels of free Al and high pH, thus suggesting

a combined e4ect. The di4erences in sample toxicity in theSeydis

:ehir plant compared with other bauxite manufacturing

plants suggest a possible variable toxicity as related to bauxiteore composition and/or manufacturing processes. 2002

Elsevier Science

Key Words: bauxite; sludge; solid residues; sea urchins; toxic-

ity test system.

INTRODUCTION

Bauxite manufacture involves ore processing leading to

alumina (AlO}xHO), which is then submitted to anelectrolytic process using molten cryolite (Na

AlF

)

and leading to metallic aluminum production (Hudson,

1987). These processes involve the production of a number

of waste materials, including sludge and solid residues

both from primary bauxite manufacturing and from the

electrolytic process. The sludge, termed &&red sludge,''

contains large amounts of aluminum and iron and lower

amounts of other metals depending on bauxite ore

composition (Hudson, 1987). Apart from these processes,

the need for high electric power associates aluminum-

producing facilities with power plants that may contribute

to the overall environmental impact, especially in the caseof coal-fueled plants. Therefore, aluminum-producing

facilities may be involved in multifaceted events of

environmental pollution, related both to the di!erent

by-products disposed of and to the site of disposal

which may a!ect marine coastal or inland dumping

areas.

Previous investigations have focused on bauxite manu-

facturing sludge, tested as plant e%uent (Trie! et al., 1995;

His et al., 1996), or as solid residues, or as marine sediment

from a coastal disposal site (unpublished data). Our pre-

vious "ndings on bauxite sludge toxicity were attributed

to aluminum and iron being present in sludge at high

nominal concentrations. (Trie! et al., 1995; Pagano et al.,

in press).

Other reports also focused on Al(III)- and Fe(III)-asso-

ciated toxicity, either as complex mixtures or as Al(III) or

Fe(III) salts (Pagano et al., 1996). Together, the evidence

provided by the previous studies pointed to developmental,

reproductive, and cytogenetic toxicity in sea urchin and oy-

ster early development induced by Al- and/or Fe-containing

complex mixtures (Trie!et al., 1995; His et al., 1996; Pagano

et al., 1989, 1996).

28

0147-6513/02 $35.00 2002 Elsevier ScienceAll rights reserved.


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FIG. 1. Location of the Seydisehir bauxite factory in Turkey.

FIG. 2. Bayer process #owsheet and sludge holding ponds.

The present study was carried out on the bauxite manufac-

turing plant in Seydis'ehir (southwest Turkey) (Fig. 1), as

a part of a more extensive study of bauxite facilities located in

four countries. A series of specimens were collected from

bauxite sludge, soil samples collected at the facilities, andwater and sediment from two disposal sites (&&holding

ponds''), receiving either red sludge or cryolite process by-

products.

The results provided further evidence for the varied toxicity

of the by-products investigated (from severe e!ects to lack of

toxicity), depending on the nature and quantity of free inor-

ganics released from these complex mixtures, and providing

further hypotheses about the relevance of the composition of

bauxite ores as related to by-product-associated toxicity.

MATERIALS AND METHODS

Red Sludge and Solid Residues

Red sludge is produced as a by-product in the bauxite

manufacturing process, as shown in Fig. 2. Red sludge is

discharged to a "rst holding pond by steel pipes after being

mixed with water withdrawn from holding ponds. In recent

years a second holding pond has been used mainly to

dispose of by-products from the cryolite process with a high

concentration of#uoride ('200 mg L\) in the water col-

umn. Solid residues derive from ground deposition of dried

red sludge at and near plant facilities, or consist of either

sediment in the red sludge holding pond or soil located at

the pond beach.Samples were taken from some selected locations in the

Seydis'ehir facilities and at the holding ponds. For compara-

tive purposes, solid residues from three other bauxite plants

located in Aghios, Nikolaos, Greece, Gardanne, France, and

Portovesme, Italy, were tested.

Sampling Collection and Storage

Soil samples (SS1 and SS2) were collected from surface

layers of the ground close to the thickener, by means of

either a brush or a shovel, respectively. The sludge sample

from a red sludge process tank (SS3) was ejected at a tem-

perature of&803C, and was collected in an iron jar. After

approximately 0.5 h, the sludge was transferred into 150-mL

polystyrene containers. Water (SS4) and red sludge (SS5)

samples were collected from the red sludge holding pond.

Moreover, a ground sample from the beach of the red sludge

holding pond (SS6) was collected to evaluate the e!ect ofsolid residue weathering. One year later, red sludge samples

from both the process tank (SS3bis) and red sludge holding

pond (SS5bis) were collected for con"rmation of the chem-

ical analysis and toxicity results. The samples were stocked

in 150-mL polystyrene containers, at the laboratory, "ltered

through a 1-mm sieve, then dried at 603C for 72 h. Other

samples were collected at the cryolite holding pond (SS7

and SS8). Water and wet samples were tested within

1 month of collection. Dry samples were stocked in the dark

at room temperature.

Chemical Analysis

Overall metal content in each sludge sample was analyzed

by destructive determinations after complete dissolution by

29BAUXITE BY-PRODUCTS IN SEA URCHINS


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TABLE 1Levels of Inorganics (mg/kg) in Seydis

:ehir Soil Samples as Detected following Strong-Acid Extraction

Sample Al Fe Mn Zn Cr Pb Ni As

SS1. Alumina plant 203,234 36,070 462.69 231.59 132.34 93.03 85.07 50.50

SS2, Near red sludge reactor 128,691 79,478 258.37 156.50 253.44 156.50 156.25 82.43

microwave disaggregation and chemical attack. Speci"cally,

0.1 g (dry wt) of each sample was contacted with 15 mL of

a mixture of concentrated strong acids [HNO

(5 mL), HCl

(3 mL), and HF (7 mL)], in a sealed polytetra#uorethylene

(PTF) vessel (bomb). After insertion of the bomb into the

microwave digestion system (MDS2100S from CEM,

Matthew, NC), the latter was operated at 60% of its max-

imum power for 15 min. The homogeneous digested solu-tion was directly injected into the ICP-OES system for

metal analysis (Tessier et al., 1979; APHA/AWWA/WEF,

1992).

To evaluate seawater release of inorganics, samples were

dried to constant weight and soaked in seawater (100 mL) in

a Jar Test System (F.6/S from Velp Scienti"c, Cambridge,

UK), stirring continuously (100 rpm) for 24 h. The super-

natant solutions, after "ltration on 0.45-m polycarbonate

"lter, were analyzed for content of seawater-released metals

by ICP-OES on a Perkin Elmer Optima 3000 System

(Norwalk, CT).

Sea Urchins

Sea urchins from the species Sphaerechinus granularis

were used; gametes were obtained and embryo cultures were

run as described previously (Pagano et al., 1986, 1993).

Controls throughout experiments were conducted as un-

treated negative controls ("ltered seawater, FSW) and

2.5;10\ M CdSO

as a positive control (Pagano et al.,

1982, 1986). Test samples were suspended in FSW at con-

centrations ranging from 0.1 to 2% (dry w/v). Exposure of

embryos (&20}30 embryos/mL) occurred throughout de-

velopment from zygote (10 min after fertilization) up to thepluteus larval stage (72 h after fertilization). This procedure

allows for direct contact throughout cleavage up to hatch-

ing (approximately 10 h after fertilization).

Sperm bioassays were conducted on sperm cell suspen-

sions by standard exposure of a 0.2% suspension of &&dry''

sperm pellet for 10 min. During exposure, test pellets were

allowed to settle and 0.5% supernatant sperm were used to

inseminate untreated egg suspensions (50}100 eggs/mL).

Changes in the fertilization success of exposed sperm were

determined by scoring the percentage of fertilized eggs in

fresh cleaving embryos (1}3 h postfertilization).

All experiments were run at least in quadruplicate. Obser-

vations of larvae were performed on living plutei (n"100

for each replicate) immobilized in 10\ M chromium sulfate

(Pagano et al., 1983, 1986). The following outcomes were

evaluated: (i) retarded (R) plutei [4

size vs normal (N)

plutei]; (ii) pathologic (P1) malformed plutei; (iii) pathologic

embryos (P2) that were unable to di!erentiate up to the

pluteus larval stage; and (iv) dead (D) embryos/larvae

[scored as dead plutei (D1) or early dead embryos (D2)]. All

observations were carried out double-blind by trained

readers, each evaluating a complete set of readings.

Statistical Analysis

The outcomes were evaluated statistically using the

and G procedures. To carry out several simultaneous com-

parisons, Dunnett's, Tukey's, and Bonferroni's tests were

used (Whorthon 1985, Zar 1996). Prior to the tests, data

were arcsin-transformed, using the correction of Freeman-

Tukey (1950) described by Zar (1996). Data analysis was

carried out using the Statistica 6.0 software. The level of

signi"cance for statistical data was always set at "0.05.

RESULTS

Chemical Analyses

A preliminary inorganic analysis was carried out on two

selected soil samples collected at the alumina plant (SS1)

and near the reactor (SS2). The samples were submitted to

strong-acid extraction, and the results, shown in Table 1,

pointed to the prevailing content of Al and Fe, 36 g kg\

(Fe) and 203 g kg\ (Al) in sample SS1, and 79 and

128 g kg\, respectively, in sample SS2. The other metals

showed levels ranking as follows: Mn'Cr:Pb:Zn:

Ni'As (Table 1). The sample set was then analyzed for the

release of soluble inorganics following a 24-h suspension in

seawater of two aliquots 0.5 and 2 g (dry wt) in 100 mL

seawater. As shown in Table 2, the highest Al(III) level was

reached by the water column sample (SS4) from the red

sludge holding pond, 1775 g L\; as for the other samples,

the levels of Al(III) measured in seawater ranged from 40 to

86 g L\, yet there was no detectable change for the any

given sample, regardless of whether it was suspended in 0.5

or 2 g/100 mL seawater. In the case of Fe(III) seawater

release, the highest levels were reached by samples SS3, SS2,

and SS1, and a shift in Fe(III) release as a function of

suspended aliquot was displayed by samples SS1 and SS5.

Regarding the other inorganics measured, only Mn showedsubstantial levels in the sediment sample from the red sludge

PAGANO ET AL.30


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TABLE 2Concentrations (g/L) of Some Selected Inorganics from Seydisehir Samples following Seawater Extraction

at Di4erent Pellet Levels?

g/100 mL Al Fe Mn

Sample (dry wt) ("396.152) ("238.204) ("257.610)

Alumina plant

SS1. Soil, alumina plant) 0.5 72 43 52 75 134 17

SS2. Soil, near reactor 0.5 60 148 15

2 61 243 67

SS3. Red sludge pellet 0.5 44 326 (0.4

2 43 327 0.4

Red sludge holding pond

SS4. Water column 2 1775 7 (0.4

SS5. Sediment pellet 0.5 82 62 57

2 86 141 125

SS6. Beach pellet 0.5 39 95 (0.4

2 40 97 2.1

?The following elements were invariably below detection limits (g/L): (Cr(4, Ni(3, Pb(30). Levels of 6$1 g/L Cu and 3$1 g/L Zn were

measured and attributed to background seawater Cu and Zn concentrations.

TABLE 3Developmental Defects Re6ecting Larval Retardation (R), Larval Malformation (P1), Developmental Arrest (P2), and Early

Embryonic Mortality Before Hatching (D2), inS. granularis Larvae Reared in Samples from a Selection of Sites at the Facilities andat a Dumping Site (99Sludge Lake::) of the Bauxite Manufacturing Plant in Seydis

:ehir, Turkey?

Treatment schedule R P1 P2 D2

Blank 6.2$2.9 3.7$0.8 2.3$0.4 0.5$0.2

Alumina plant

0.5% soil, alumina plant

(SS1)

4.5$2.3 6.8$0.9 1.8$1.4 0.0$0.0

0.5% soil, near reactor (SS2) 9.0$4.6 29.5$10.9 15.5$2.1 0.0$0.0

0.5% red sludge (pellet) (SS3) 4.8$1.8 6.3$1.8 0.5$0.5 0.0$0.02% red sludge (supernatant)

(SS3)

13.3$3.6 25.8$8.8 19.8$7.7 0.0$0.0


1% water column (SS4) 7.8$6.1 8.3$4.4 3.0$0.4 0.0$0.0

2% water column (SS4) 0.0$0.0 0.0$0.0 0.0$0.0 100.0$0.0

0.5% lake sediment pellet (SS5) 26.8$18.6 11.5$2.2 3.0$1.6 0.0$0.0

2% lake sediment pore water (SS5) 3.5$2.0 6.3$2.4 4.0$1.6 0.0$0.0

0.5% beach sediment pellet (SS6) 4.3$1.0 6.0$1.6 1.0$0.7 0.0$0.0

2% beach sediment pore water (SS6) 3.3$0.8 5.0$0.7 2.5$1.0 0.0$0.0

?Quadruplicate experiment.

holding pond (SS5), up to 125 g L\, and in the soil sample

close to the reactor (SS2), 67 g L\, following suspension

of a 2-g pellet in 100 mL seawater. The other elements

analyzed for showed levels below detection limits (Cr(4,

Ni(3, Pb(30), or, in the case of Cu and Zn, measured

levels were not changed by increasing amounts of sample;

suspended and, thus, were attributed to background sea-

water levels (Table 2). In conclusion, the samples only re-

leased increasing and substantial amounts of Fe(III), and

only two samples (SS2 and SS5) released increasing Mn(II)

levels. A particular case was the water column sample (SS4)

from the red sludge holding pond, which showed exceeding-

ly high Al(III) levels and a high pH (:12).

Sea Urchin Bioassays

When S. granularis embryos were reared in the samples

from the Seydis'ehir plant, the most severe toxicity was

exerted by the 2% dilution of the SS4 sample (water column

from red sludge holding pond), with 100% early embryonic

mortality (D2), as shown in Table 3. Another sample

displaying signi"cant toxicity (P(0.005) was the water



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TABLE 4Developmental Defects in S. granularis Larvae Reared in

a Selection of Samples (0.5% dry wt/vol) from the BauxiteManufacturing Facilities in Seydis

:ehir (TR), Gardanne (F),

Aghios Nikolaos (GR), and Portovesme (IT)?

Treatment Schedule R P1 P2

Blank 5.3$1.0 5.7$1.1 1.7$0.5Cd(SO

)

2.5;10\ M 0.0$0.0 0.0$0.0 100.0$0.0

TR-SS1 11.0$2.8 13.2$4.4 14.6$12.0

TR-SS2 8.6$2.5 46.8$11.6 22.2$14.7

F-10 10.8$3.1 50.0$10.8 5.6$0.7

F-12 16.0$3.1 34.2$8.3 8.8$5.1

F-20 2.6$1.6 49.0$12.9 39.6$12.1

F-21 11.0$2.4 11.3$3.7 4.8$3.3

GR-604 11.0$3.0 42.4$11.3 3.6$0.8

GR-719 16.4$3.4 32.2$8.9 6.0$1.5

IT-011 0.0$0.0 0.0$0.0 100.0$0.0

IT-522 0.0$0.0 3.0$3.0 97.0$3.0

IT-489 8.0$2.9 14.8$5.3 0.6$0.4


TABLE 5Fertilization Rate (FR) and O4spring Quality (P1, P2) in

S. granularis Larvae following Exposure of Sperm to SomeSelected Samples from the Facilities and at the 99Sludge Lake::of the Bauxite Manufacturing Plant in Seydis

:ehir?

Treatment Schedule FR P1 P2

Blank 92.4$0.7 6.17$1.7 3.4$0.7

Cd(II) 2.5;10\ M 2.0$1.2 ND ND

Alumina plant

0.5% soil alumina

plant (SS1)

86.0$0.9 3.0$1.5 4.3$2.7

0.5% soil near reactor

(SS2)

89.0$0.7 5.3$1.7 5.3$1.3

0.5% red sludge

(pellet) (SS3)

88.0$0.6 5.0$3.0 3.8$2.6

2% red sludge

(supernatant) (SS3)

38.0$3.5 24.8$11.6 53.5$17.8


1% water column

(SS4)

97.0$0.4 7.5$2.2 2.8$0.6

2% water column

(SS4)

98.0$1.3 9.8$4.5 3.0$2.3

0.5% lake sediment

pore water (SS5)

65.0$2.9 7.8$2.8 2.0$1.7

2% lake sediment

pore water (SS5)

95.0$0.8 16.8$5.0 2.5$0.9

0.5% beach sediment

pellet (SS6)

99.0$0.4 4.5$1.2 2.8$1.1

2% beach sediment

pore water (SS6)

98.0$1.2 4.5$1.2 4.0$1.7


component (SS3 supernatant) of the red sludge, with in-

creased malformations (P1), prelarval arrest (P2), and larval

retardation (R). As for solid residues (soil and pellet sam-

ples), the only one that resulted in developmental toxicity

was the soil sample collected near the reactor (SS2), with

'50% developmental defects (as R#P1#P2).

Another quadruplicate experiments was carried out to

compare the relative toxicities associated with a series of

solid residue samples from four bauxite plants in Seydis'ehir

(TR), Gardanne (F), Aghios Nikolaos (GR), and Portovesme(IT). Samples were selected according to previous evidence

for varied degrees of toxicity at di!erent locations of the

above facilities, and S. granularis embryos were reared in

0.5% of the dry pellet. Table 4 reports the results of the

comparative test with the solid residue samples from the

four bauxite plants. Among the Seydis'ehir samples tested

the relatively high toxicity of SS2 resulting in 47% mal-

formed larvae (P1) and 22% prelarval arrest (P2) was con-

"rmed, whereas the SS1 sample was con"rmed to be less

toxic. Also con"rmed were the toxicity data for the samples

collected at the other facilities either previously (F, May

1996; GR, January 1998) or contemporaneously (IT, May1998). This con"rmation held true for both the French and

the Italian sample subsets, with the highest toxicities dis-

played by samples F-20 (:90% P1#P2) and IT-011

(100% P2), compared with relatively non-toxic samples,

such as F-21 and IT-489. As for the samples from Aghios

Nicolas (GR), their toxicities were intermediate and did not

di!er signi"cantly from each other (Table 4).

When S. granularis sperm were suspended for 10 min in

seawater with Seydis'ehir samples, the supernatant from red

sludge (SS3) was the only sample both exerting signi"cant

spermiotoxicity (FR"38%) and a!ecting o!spring quality

(:78% P1#P2) (Table 5).

Other data, not shown in the present report, include the

following: (a) con"rmation of the relative toxicities of

Seydis'ehir samples (SS3bis and SS5bis) collected 1 year later

(June 1999); (b) the lack of any signi"cant cytogenetic e!ects;

and (c) the lack of any e!ects from either the water column

or sediment from samples collected at the cryolite holdingpond (the dumping site of the electrolytic process).

DISCUSSION

Chemical Analyses

Two sets of data have been obtained by analyzing

Seydis'ehir samples either following strong-acid extraction

or following a 24-h extraction in seawater. The former

procedure leads to disruption of crystalline or amorphic

solid structures, thus providing exhaustive information on

the chemical composition of a complex mixture as for

example, in the present study, bauxite manufacturing by-products. The data reported in Table 1 represent an

example of this kind of information which, however,

may conceal the environmental availability of a number of

PAGANO ET AL.32


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components that may remain immobilized in the solid

structure and, thus, may not contribute to solid residue-

associated environmental e!ects. By comparing the data

reported in Tables 1 and 2, respectively, some inorganic

components, e.g., Cr and Pb, may result in noticeable levels

if analyzed following strong-acid extraction, yet their levels

were below detection limits when extraction was carried out

by soaking samples in seawater for 24 h. Thus, the presentas well as previous experience (Pagano et al., in press) point

to the need to reconsider the strong-acid extraction proced-

ure which may itself provide some misleading information

relative to the toxicity of complex mixtures. On the other

hand, a &&mild'' extraction procedure, e.g., seawater extrac-

tion, may provide some more realistic information on the

levels of environmentally available contaminants released

from the complex mixtures being examined.

Based on the results of the present study and on previous

analytical datasets from bauxite sludge and solid residues

(Trie! et al., 1995; Pagano et al., in press), the roles of the

mixture components may appear to di!er somewhat amongthe di!erent facilities (Seydis

'ehir vs Gardanne vs Por-

tovesme). Namely, the chemical composition and environ-

mentally availability of the inorganics involved may change

from one plant to another plant, in that (a) the main nom-

inal components, i.e., Al and Fe, may (or may not) be

released from solid residues to a di!erent extent, possibly as

a function of mineralogic di!erences in bauxite ores used at

the di!erent facilities; and (b) the role(s) for the &&minor''

components may be relevant to the resulting toxicity, due to

components that may vary in their absolute levels and,

again, in their release from the mixture. As a clear example

of this observation, Zn was present at very low levels in bothSeydis

'ehir samples and in bauxite sludge from Gardanne,

whereas high Zn levels and extensive release in seawater

were directly associated with sample toxicity at the Por-

tovesme facilities (Pagano et al., in press).

The subject of metal speciation has not been consi-

dered in the present study, yet its relevance in evaluating

environmental availability and toxicity deserves further

investigations.

Sea Urchin Toxicity Testing

The most severe developmental toxicity was exerted bytwo wastewater samples, namely, the water column from

the red sludge lake (SS4) and the supernatant from the

red sludge (SS3), the former resulting in early embryolethal-

ity (100% D2). This e!ect could possibly be attributed to

a very high pH (:12), at which aluminum has high solubil-

ity in the Al(OH)\

form, resulting in a pH shift of approx-

imately one unit in bioassay medium at the concentration

tested. At the same time, sample SS4 was found to be

contaminated by a relatively high Al(III) level (1700 g L\,

or :5;10\ M); thus, both increased pH and increased

Al(III) contamination may have contributed to SS4-asso-

ciated embryolethality (Pagano et al., 1985, 1996). The re-

spective contributions of high Al(III) levels and high pH

toxicity await disentanglement in a further study.

Among solid samples, only the soil sample collected near

the reactor (SS2) resulted in a signi"cant increase in devel-

opmental defects (P1#P2), ranging from 30 to 70% of

larvae (Tables 3 and 4); it is worth noting that the SS2sample showed a concentration-dependent release of Fe(III)

and Mn(II) (Table 2).

Conversely, the SS6 sample (beach soil at the red sludge

holding pond) resulted in no toxicity and failed to show any

seawater release of Fe(III) or Mn(II), consistent with

weathering processes having occurred in SS6.

The overall lack of solid residue-associated toxicity in

Seydis'ehir samples (excepted for SS2) di!ered from the data

previously obtained on bauxite solid residues in Gardanne

and Portovesme, while it was consistent with an analogous

lack of severe toxicity observed in soil samples collected

outside the facilities at Aghios Nikolaos. Comparative test-ing of solid residue toxicity provided con"rmation of the

previously observed di!erences in sample toxicity, which

were una!ected by sample aging, since the bioassay (data in

Table 4) was conducted in October 1999 on samples having

aged from 1

years (Seydis'ehir and Portovesme samples) to

3

years (Gardanne samples). Thus, it could be observed

that the relative toxicity (or lack of toxicity) was maintained

in samples tested more than 3 years later. Among the

di!erent sites, it could be seen that the most toxic

sites corresponded to samples IT-011 (Portovesme), causing

100% of developmental arrest (P2), and F-20 (Gardanne)

resulting in approximately 90% malformations (P1)plus developmental arrest (P2). Thus, both Seydis

'ehir

and Aghios Nikolaos samples were con"rmed to result

in lesser developmental toxicity, when compared with

the most toxic samples from Portovesme and Gardanne.

Consistent with the above-discussed variation in sample

composition, the di!erences in toxicity outcomes could

be related to possible di!erences in the environmental

availability of the contaminants present in the solid residues

at di!erent levels due to seawater release, as was the

case for the high zinc levels in Portovesme (Pagano et al., in

press).

Consistent with the outcomes of an overall lack of devel-opmental toxicity for solid residues in Seydis'ehir samples,

only red sludge supernatant (SS3) exerted a spermiotoxic

e!ect, which was followed by the observation of increased

malformations and prelarval arrest in the o!spring of

treated sperm (Table 5). A general statement should be

made regarding the choice of using a marine organism in

toxicity testing for a terrestrial environment. First, it should

be stressed that bauxite sludge is a marine contaminant as in

the Gardanne, Aghios Nikolaos, and Portovesme facilities,

whose sludge is disposed of in marine coastal areas. The



7/7

Seydis'ehir facilities are an exception due to their distance

('200 km) from the coast; hence, the two holding ponds

are used as dumping sites. A second, more general argument

relates to the utilization of the sea urchin test system in

a variety of subjects and substrates, e.g., in testing pharma-

ceutical drugs, industrial chemicals, and complex mixtures

not con"ned to the marine environment, e.g., river sediment

and industrial sludge (Pagano and Trie!, 1992; Paganoet al., 1993, 2000; Graillet et al., 1993; Trie! et al., 1995).

Thus, the utilization of sea urchin bioassays in testing

Seydis'ehir samples of sludge, water column, and solid resi-

dues may be envisaged as one additional case for evaluating

complex mixture toxicity, independently of whether bauxite

by-products are disposed of in the marine environment.

CONCLUSIONS

Bauxite manufacturing by-products can be viewed as

a matter of environmental concern that remains to be elu-

cidated further. This holds true for both bauxite sludge andsolid residues. A striking variability in bauxite by-products

can be recognized, both among samples from the same

facilities and among samples from di!erent factories. Major

sources of variability, with respect to both analytical and the

toxicity outcomes, may be variable ore composition and

variable release of toxic contaminants from bauxite by-

products, including their main components (Al and/or Fe)

and some &&minor'' components, such as Mn, Zn and Pb.

The use of mild extraction procedures prior to analytical

determinations is strongly suggested by the present studies,

since strong-acid extraction may lead to unrealistic informa-

tion in terms of environmental availability of complex mix-ture components.

Thus, two related overall lessons from the present and

previous studies point to (i) the need for appropriate and

realistic extraction procedures, and (ii) the variability in the

environmental e!ects of bauxite by-products as related to

the recognized variability in ore composition.

ACKNOWLEDGMENTS

The authors thank the ETIBANK, Ankara, for kindly providing access

to their facilities in Seydis'ehir. This study was supported by the European

Commission, Projects EV5V-CT94-0550 and ENV4-CT96-0300 and, in

part, by the Italian Labor Ministry. Thanks are due Dr. Norman M. Trie !for critical revision of the manuscript. The Zoological Station, Naples,

provided support by their "shery service (Pasquale Sansone and co-

workers).

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