Posters

P 26 The pattern of polychlorinated biphenyls in fish from the surface layer and the deep sea of the Atlantic and Indian Ocean

Regina Fischer and K. Ballschmiter

Abteilung Analytisehe Chemie, Universit~t Ulm, Oberer Eselsberg, D-7900 Ulm, Federal Republic of Germany

Muster der polychlorierten Biphenyle in Oberfliichen- und Tiefseefischen des Atlantischen und des Indischen Ozeans

Introduction

Marine animals such as fish, penguins or seals are often used as bioextractors in order to investigate the occurrence of anthropogenic compounds in the marine environment. Thus, carefully selected fish samples of defined biotopic and geo- graphic origin can provide information about input pathways and transport mechanisms in the water column [1 - 3].

As the transport from the ocean surface to the deep sea occurs mainly by the detritus fall-out, this is likely to favor the enrichment of more hydrophobic, i.e. higher-chlorinated, compounds with increasing depth ("liquid chromatography with solid mobile phase"). The effect should be reflected by the pattern of the higher-chlorinated PCB in deep-sea fish.

In this work, the PCB patterns of surface-living fish from the South and Northwestern Atlantic and from the Indian Ocean are compared to those of deep-sea fish caught near the Bermudas.

The selection of samples allows a geographically broad- spread description of the PCB pattern in the marine surface layer and of the situation in the deep-water region of the North Atlantic. Isomer-specific identification was performed by using high-resolution gas chromatography with mass selective detec- tion (HRGC/MSD) in the selected-ion monitoring (SIM) mode. The isomer-specific identification of technical PCB mixtures has been published recently [4].

Experimental

Type and origin of samples:

Grouper (Epinephelussp.). A predator feeding mainly on crustaceans; it inhabits coastal waters and coral reefs in moderate depths rarely exceeding 200 m; origin: Virgin Islands (1983).

Chopper. Predatory species of the bass family (Epinephelinae) inhabiting reefs and coastal waters; origin: Barbados (1981).

Yellowtail (Seriola lalandi). A circumglobal predatory species restricted to subtropical coastal waters in depths around 50 m; origin: Cape Town (South Africa 1985).

Rock bass (Epinephelus sp.). Predator feeding mainly on crustaceans; it inhabits the temperate oceans down to 50 m; origin: the Maldives (Indian Ocean 1986).

Sixgill shark (Hexanchus griseus). A pelagic and benthic species found in deep water (100-1,500 m) of all oceans; origin: Bermudas (1982).

Oilfish (Ruvettus pretiosus). Pelagic mackerel which inhabits the tropical and temperate parts of the oceans in 2 0 0 - 500 m depth; origin: Bermudas (1982).

Deep-sea bass (Eretmophoridae). Stationary ground-feeding (600-2,600 m) species; origin: Bermudas (1982).

Sample pretreatment. Liver and muscle tissue of fish were homogenized with quartz sand in a mortar and extracted as described previously [2]. Sulfuric acid clean up [5] was followed by fractionation on silica gel (3 % H20) using hexane as the first

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a. c i~ qo to

c c

g

1

0

-1 C13

O.. [;

CI 4 C15 CI 6 CI 7

1 C18

Fig. 1. PCB patterns ofchlorohomologues in surface-living fish. [] Chopper (Barbados); �9 Grouper (Virgin Islands); [] Yellowtail (South Africa); [] Rock Bass (Maldives)

eluent (LCI) and hexane/20% dichloromethane as the second eluent (LC2). The LC1 fractions known to contain all PCB were subjected to HRGC/MSD analysis.

HRGC/MSD conditions. Stationary phase: DB 5 (methyl-5% phenyl-polysiloxane), 60 m x 0.25 mm; film thickness 0.27 lam. Injection port: 280~ oven: 120~ 5 min (3 min splitless); 2~176 10rain. Transfer line: 280~ EI source: 230 ~ C; mass analyzer (quadrupole): 200 ~ C.

Detection was performed in the SIM mode using two ions (M +, (M + 2)+) for each degree of chlorination. The optimized separation parameters had been determined before by HRGC/ ECD with the same stationary phase.

Results

PCB pattern analysis was done by comparing the relative amounts of the various chlorination degrees, which were calculated as the corresponding percentages of area sum relative to the total for each sample. The standard for the comparison was a 1 : 1 : 1 mixture of Clophen A30/50/60.

Figure 1 shows the patterns of the PCB chlorohomologues of the four surface-living fishes from Barbados (Chopper), the Virgin Islands (Grouper), South Africa (Yellowtail) and the Maldives (Rock bass) in relation to that of the standard mixture.

The deviations relative to the standard mixture are small for the tetra- to heptachlorobiphenyls, whereas the tri- and octachlorobiphenyls are present to a lesser extent in the samples than in the standard. This may be due to minor input for both groups and, in the case of the trichloro congeners, also due to biodegradation.

Among those geographically widespread samples, variations are astonishingly small, indicating a global equipartition of the PCB pattern in the marine surface water.

The patterns of the three very different types of deep-sea fishes from the Bermudas (Fig. 2) give a continuous increase in the sample: standard ratio from lower towards higher degrees of chlorination. It can be best explained by an extended accumulation of the latter congeners, and by a reduced input as well as a certain degree of biodegradation of the lower- chlorinated biphenyls. This is extremely pronounced in the sixgill shark (Hexanchus griseus), which is not a pelagic deep- sea fish but has a very high rate of metabolism due to its steady

Poster

X C1 n (sample) log �9

C1 n (sLandard)

2,

$

s l S,

7 S,

-1 '

C13 Cl 4 C15 C16 C17 C18 C19 -2

Fig. 2. PCB patterns of chlorohomologues in deep-sea fish. [] Oil fish (Bermuda); �9 Deep-sea Bass (Bermuda); [] Sixgill Shark (Bermuda)

motion and predatory way of living. The patterns of the other two deep-sea fishes, a stationary deep-sea bass (Eretmophoridae) and an oilfish (Ruvettus pretiosus), a pelagic mackerel, are very similar to each other, with even less variation than is observed in the surface-living fish.

A direct comparison between a deep-sea fish and a surface- living species from the same area (Fig. 3) very clearly reveals the increasing enrichment of the more stable and more lipophilic hepta- to nonachlorobiphenyls with increasing depth.

Discussion

A pronounced enrichment of the total PCB in deep-sea fish relative to surface fish was reported previously [3]. The high relative amounts of higher-chlorinated biphenyls accumulated in deep-sea fish cannot be explained by biodegradation of the lower-chlorinated congeners alone. The above results support the proposed mechanism of a mainly particle-bound, solid and liquid phase equilibrating transport of hydrophobic compounds from the surface of the ocean to the deep sea.

A physico-chemical parameter of this behaviour will be the water-solubility and its counterpart, the n-octanol/water parti-

Cln(sample) log �9

% C1 n (sLandard)

i

~ 1

-1

-2 C13 C1 d C15 CI E CI 7 C] 8 C19

Fig. 3. Comparison between the PCB patterns of a surface-living fish and a deep-sea fish from the same origin. [] Deep-sea Bass (Bermuda) - deep sea; [] Chopper (Barbados) - surface

tion coefficient, of the compounds. The hexachlorocyclohexanes (C6H6C16) and mirex (CloCllz) mark extremes to this aspect of transportation for the chlorinated hydrocarbons [3].

References

1. Zell M, Ballschmiter K (1980) Fresenius Z Anal Chem 304: 337

2. Ballschmiter K, Buchert H, Bihler S, Zell M (1981) Fresenius Z Anal Chem 306:323

3. Kraemer W, Buchert H, Reuter U, Biscoito M, Maul DG, Le Grand G, Ballschmiter K (1984) Chemosphere 13 (11): 1255

4. Ballschmiter K, Schaefer W, Buchert H (1987) Fresenius Z Anal Chem, in press

5. Jensen S, Reutergardh L, Jansson B (1983) FAO Fish Tech Pap 9:21

Fresen ius Z Ana l C h e m (1987) 3 2 7 : 4 2 - 4 3 �9 Spr inger -Ver lag 1987

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