Polychlorinated biphenyls in different trophic levels froma shallow lake in Argentina

Mar�ııa de los A. Gonz�aalez Sagrario a,b, Karina S.B. Miglioranza b,c,*,Julia E. Aizp�uun de Moreno c, V�ııctor J. Moreno c, Alicia H. Escalante b,d

a Laboratorio de Invertebrados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata,

Funes 3250, 7600, Mar del Plata, Argentinab Consejo Nacional de Investigaciones Cient�ııficas y T�eecnicas (CONICET). Av. Rivadavia 1917, 1033, Capital Federal, Argentina

c Laboratorio de Ecotoxicolog�ııa, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata,

Funes 3350, 7600, Mar del Plata, Argentinad Laboratorio de Limnolog�ııa, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata,

Funes 3250, 7600, Mar del Plata, Argentina

Received 14 November 2000; received in revised form 14 February 2002; accepted 25 February 2002

Abstract

Polychlorinated biphenyls (PCBs) were determined in a aquatic community from Los Padres Lake, Argentina.

Twenty four PCB congeners from tri- to octa-chlorinated isomers were detected and quantified using conventional gas

chromatography with electron capture detector (GC-ECD). The aim of this study was to investigate the concentrations

of PCBs in freshwater organisms from a shallow lake of Argentina. Stems of bulrush (Schoenoplectus californicus),

whole tissues of false loosestrife (Ludwigia sp.) and grass shrimp (Palaemonetes argentinus), and liver, gonads, muscle

and mesenteric fat (if present) of fish species (Rhamdia sapo) and (Oligosarcus jenynsi) were analyzed. Two areas were

selected to macrophytes sampling: the input area, main PCB source of the lake (Station 1), and the output area, a

potential anoxic zone (Station 2). Macrophytes from Station 1 bioconcentrated higher total PCB levels than Station 2,

showing that the former have received PCBs washed down from upstream areas. Penta- and hexa-congeners were

enriched relative to other congeners in animal biota and macrophytes from Station 1, consistent with commercial

mixture of Aroclor 1254 used in this region. In bulrush from Station 2 a predominance of tri- and tetra-chlorinated

congeners was observed. Grass shrimp showed the lowest PCB values among animal biota. PCB concentrations in fish

tissues varied with the species and the gonadal development. Mesenteric fat, only present in post-spawning organisms of

R. sapo, had the highest values of PCBs relative to other tissues. A clearance of total PCBs in ovaries of post-spawning

females of R. sapo was observed, but not in testes. O. jenynsi/P. argentinus biomagnification factor (BMF) had a mean

value of 18.7. Congeners 44, 52 and 151, showed the highest BMF values, being 64, 66 and 62, respectively. These values

would be a consequence of the low depuration rate of 44 and 52 congeners with orthochlorine substitution conducted

by O. jenynsi and the high depuration rate of congener 151, which lacks 4 40- chlorine substitution, carried out by grass

shrimp. Although the most of congeners have been biomagnified, they did not clearly displayed a concomitantly in-

creasing with logKow.� 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Polychlorinated biphenyls; Macrophytes; Grass shrimp; Fish; Biomagnification factor; Polymictic lake

Chemosphere 48 (2002) 1113–1122

www.elsevier.com/locate/chemosphere

*Corresponding author. Address: Laboratorio de Ecotoxicolog�ııa, Facultad de Ciencias Exactas y Naturales, Universidad Nacional

de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina. Tel.: +54-223-4752426; fax: +54-223-4753150.

E-mail address: kmiglior@mdp.edu.ar (K.S.B. Miglioranza).

0045-6535/02/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.

PII: S0045-6535 (02 )00149-2

1. Introduction

Polychlorinated biphenyls (PCBs) are ubiquitous

contaminants in aquatic environments as a result of

uncontrolled spillage, stream transport, surface runoff

and atmospheric deposition. Many studies have focused

on the distribution of PCBs within lake ecosystem in an

attempt to predict the factors influencing the accumu-

lation of PCBs by biota. Because of the low water sol-

ubility of PCBs, a strong relationship between the

concentration of total PCBs and the lipid content of

animal biota has been observed in different water bodies

(Van der Oost et al., 1988; Niimi, 1996; Fisk et al., 1998).

Recent research has attributed the variation in congener

bioaccumulation to: (a) steric changes in the biphenyl

molecule with increasing chlorination, (b) partitioning

among different environmental compartments and (c)

differences in Kow (Russell et al., 1999).Van der Oost et al. (1988) suggested that the cong-

eners distribution in a particular trophic level was better

described as a function of the time available to accu-

mulate the contaminants (i.e. age of organisms) than

simple partitioning among water, sediments and biota.

Therefore, the distribution of PCB congeners within any

particular organism in a waterbody is the result of

complex interactions among the congener composition

of the original PCB source, removal and transport

mechanisms within the ecosystem, chemical and physical

properties of the congeners which affect the uptake into

the organisms, route (e.g. diet) and exposure time. From

an ecological viewpoint, biomagnification theory implies

that biomagnifying contaminants can play an useful role

in determining feeding relationships and consequently,

the trophic community structure (Russell et al., 1999).

Moreover, it has been recently stressed that the patterns

and concentrations of hydrophobic pollutants are de-

termined by internal physiological processes, such as

lipid metabolism and biotransformation (Barron, 1990).

In Argentina, there are few works about PCB levels

in estuarine ecosystems (Lanfranchi et al., 1998; Menone

et al., 2001).

The aim of this study was to quantify PCBs in or-

ganisms of different trophic levels from a shallow lake in

Argentina. Moreover, to know whether lipid content

and trophic level influence the accumulation of PCBs in

this ecosystem, and to determine the biomagnification

factor (BMF) of main PCB congeners in the predation–

prey relationship O. jenynsi–P. argentinus.

2. Materials and methods

This work was performed in Los Padres Lake, a

shallow waterbody, 2.16 km2 surface, located in the

southeastern area of Buenos Aires province, Argentina,

(37� 550–38� 020 South; 57� 340–57� 330 West), betweenJuly and November 1997 (Fig. 1). The annual average

temperature was 13.5 �C, the minimum mean in July was7 �C and the high average for January was 19.2 �C(Bocanegra et al., 1993).

2.1. Sampling

Samples from different trophic levels were collected.

The organisms selected were bulrush (Schoenoplectus

californicus), a very common littoral macrophyte; false

Fig. 1. Map of Los Padres Lake located in the southeastern area of Buenos Aires Province, Argentina. S1: Station 1 and S2: Station 2.

1114 M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122

loosestrife (Ludwigia sp.), a rooted floating leaved; grass

shrimp (Palaemonetes argentinus), living associated with

aquatic plants, and two fish species: Oligosarcus jenynsi

(Characidae), an omnivorous species feeding mainly on

grass shrimp, and Rhamdia sapo (Pimelodidae), a bot-

tom feeder. O. jenynsi and the most of R. sapo females

were captured in pre-spawning stage. A few male spec-

imens (pre- and post-spawning) and post-spawning fe-

males of R. sapo were also analyzed.

Bulrush and false loosestrife samples were collected

from two sites, close to Los Padres Creek, the input area

(Station 1), the main PCB source of the lake, and La

Tapera Creek, the output area (Station 2), using a

20� 20 cm square sampler with mobile side. Grass

shrimp was caught by means of a hand net and fish

species using different types of bait. Immediately after

catch, samples were wrapped in clean aluminum foil and

ice and transported to the laboratory. Total bulrush

stems, whole tissues of false loosestrife and grass shrimp,

and gonads, liver, mesenteric fat and muscle from fish

were analyzed. Samples from the same species and place

were pooled.

2.2. Analytical methods

Samples were frozen and stored at �20 �C until

analysis. After determining length and weight of the

whole thawed fish, tissues of liver, gonads, mesenteric fat

(only present in immature organisms of R. sapo) and

muscle fillets were removed. The tissues from 3 to 8 fish

Table 1 were then pooled according to sex and gonad

development. Samples were homogenized using a War-

ing blender.

2.2.1. Extraction

Subsamples of 5–10 g of tissues were ground in a

mortar with anhydrous sodium sulfate and extracted

with a 50:50 mixture of hexane and dichloromethane in

a Soxhlet apparatus for 8 h (Muir et al., 1988). Extracts

were concentrated under nitrogen to �3 ml. Lipids wereremoved from the extracts by gel permeation chroma-

tography (GPC) in Bio Beads S-X3 (200–400 mesh)

(Bio-Rads Laboratory, Hercules, California) and ex-

tracts were subfractionated by silica gel chromatography

as previously described by Metcalfe and Metcalfe

(1997). The lipid fraction from the GPC was evaporated

to dryness to calculate the lipid content.

2.2.2. Analysis

All PCB congener analyses were performed as de-

scribed by Metcalfe and Metcalfe (1997) using a Varian

3500 gas chromatograph equipped with an electron

capture detector, and 60 m DB-5 column. Target ana-

lytes for the present study were 24 individual congeners:

IUPAC # 18, 31, 28, 52, 49, 47, 44, 66, 101, 99, 87, 110,

118, 105, 149, 151, 153, 156, 138, 180, 170, 199, 195 and

194. The sum of them is defined as total PCBs. Quan-

tification of all PCB congeners was done using an

external standard consisting of a mixture of PCB cong-

eners (CLB-1 series), purchased from the National Re-

search Council, Canada, supplemented with congeners

52, 99 and 105 purchased from Ultra Scientific (Rhode

Island). The limits of detection for analysis of PCB

analytes were calculated as three times the standard

deviation of the detector response in repetitive injec-

tions of sample blanks, according to Keith et al. (1983),

ranging between 0.3 and 1.0 ng/g lipid.

2.2.3. Quality control

Procedural blanks, a cod liver oil standard reference

material (SRM 1588) purchased from the National In-

stitute of Standards and Technology (NIST), were an-

alyzed for QA/QC purposes. Analysis of the NIST

reference material indicated that the PCB analytes were

quantified to within �10% of their certified concentra-tion. Analysis of the NRC reference material indicated

that the PCB analytes were quantified to within �7% oftheir certified concentration. Duplicate analyses of sam-

ples gave results that varied by less than 10%.

The concentrations of individual PCB congeners

were calculated on a lipid-normalized basis, which is an

important factor for the bioconcentration of hydro-

phobic compounds in animal tissues. Various authors

have suggested normalizing concentrations of pollutants

to the lipid content in order to reduce intra-species and

inter-species variability (Pastor et al., 1996).

The BMF was calculated as mean concentration in

O. jenynsi muscle/mean concentration in grass shrimp

whole tissues.

3. Results

The species collected, sample sizes, lengths and

weights of animal biota are given in (Table 1). Lipid

contents (%) and mean concentrations of total PCBs

(ng/g wet wt. and ng/g lipid wt.) of the analyzed biota

are shown in Table 2.

Since PCB compounds are hydrophobic (high Kow),their concentrations based on amounts of lipids were

considered to be physiologically more relevant in animal

biota than those on wet or dry weight basis. PCB values

of different trophic levels ranged from 3.5 to 730 ng/g

wet wt. and from 0.3 to 12.7 lg/g lipid in the case of theanimal biota.

The highest PCB levels were found in fish species,

consistent with the higher trophic level. There was an

apparent relationship between total PCB levels (ng/g wet

wt.) and lipid content, but R. sapo muscle tissue. PCB

congeners from 3 to 8 chlorine atoms were detected in

tissues from all samples.

M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122 1115

3.1. Macrophytes

Lipid and PCB levels expressed as ng/g wet wt. in

false loosestrife were higher than those in bulrush (Table

2). The differences between macrophytes from both

sampling sites were more apparent when the congener

group levels were expressed as relative abundance (Fig.

2). PCB concentrations of both macrophytes found in

Station 1 were higher than those from Station 2. A clear

predominance of penta- and hexa-chlorinated isomers

in macrophytes from Station 1 has been registered, al-

though differences between both species were noted re-

garding individual congeners (Table 3).

On the other hand, in the Station 2, the bioconcen-

tration pattern has exhibited differences in both macro-

phytes. Tri- and tetra-chlorinated congeners were the

Table 1

General data of aquatic biota sampled in Los Padres Lake

Common name Species Sex N Total length (mm) Total weight (g)

Bulrush S. californicus – 4 pools of 20 – –

False loosestrife Ludwigia sp. – 2 pools of 20 – –

Grass shrimp P. argentinus n.d. 3 pools of 45 22.1a (19.4–24.8)b 0.077 (0.043–0.132)

– O. jenynsi a-pre 1 pool of 8 169.8 (145–185) 53.3 (31.8–69.3)

Catfish R. sapo a-pre 1 pool of 5 430 (402–466) 1013.8 (950.8–1030)

a-post 1 pool of 2 427.5 (425–430) 946.5 (880.9–1012)�- pre 1 pool of 2 405 (393–417) 655.4 (590.8–712.1)�- post 1 pool of 2 366.3 (335–384) 550.1 (385.3–718.6)

n.d.: non-determined; a-pre: pre-spawning female; a-post: post-spawning female;�- pre: pre-spawning male;�- post: post-spawning male.aMean.bRange.

Table 2

Gonadal development, sex, tissues and lipid content of the biota analyzed

Organisms Sex Tissues Lipids (%) PCB concentration

Wet weight (ng/g) Lipid weight (ng/g)

Bulrush – Stema ;b 0.2 5.3 –

0.5 3.5

False loosestrife – Wholea ;b 1.9 16.9 –

1.9 4.1

Grass shrimp n.d. Whole 3.0 9.7 323.3

O. jenynsi a-pre Ovary 4.9 135.7 2775.5

Liver 4.9 42.0 848.8

Muscle 0.9 29.3 3289.9

Catfish a-pre Ovary 4.8 43.3 894.8

Liver 1.9 18.6 1002.2

Muscle 1.3 106.2 8364.6

a-post Ovary 1.5 11.8 767.5

Liver 3.6 13.2 371.6

Muscle 1.6 79.2 4950.6

Mesenteric fat 65.4 389.7 595.9

�- pre Testes 1.2 10.5 900.0

Liver 2.6 67.7 2400.4

Muscle 1.3 153.6 12 693.4

�- post Testes 2.0 12.9 650.3

Mesenteric fat 66.2 730.6 1103.8

Total polychlorinated biphenyls (mean values) are expressed as ng/g wet wt. and ng/g lipid wt.

a-pre: pre-spawning female; a-post: post-spawning female; �- pre: pre-spawning male; �- post: post-spawning male.a Station 1.b Station 2.

1116 M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122

main groups in bulrush (74% of total PCBs), dominated

by congener 18, 28 and 49 while false loosestrife showed

the highest concentrations of penta- and hexa-congener

groups (80% of the total PCBs) with 138, 153, 110, 118

and 101 as the main congeners.

3.2. Grass shrimp

Whole tissues of grass shrimp showed the lowest PCB

values among animal biota (Table 2). Animal biota of

different trophic levels exhibited a common PCB signa-

ture, dominated by highly chlorinated congeners (5 and

6 Cl) representing 85% of the total PCBs. These con-

gener groups were dominated by isomers 138, 153, 110,

118 and 101.

3.3. Fish species

Pre-spawning female of O. jenynsi, a low-fat fish,

accumulated the highest PCB levels (ng/g wet wt.) in

ovary, followed by liver and muscle. The main congener

groups in liver and muscle were tetra-, penta- and hexa-

chlorinated while in ovary penta-, hexa- and hepta. On

the other hand, post-spawning organisms of R. sapo

presented mesenteric fat, with the highest PCB concen-

tration (ng/g wet wt.) in both sexes. PCB levels in pre-

spawning ovary of R. sapo was much higher than in

post-spawning. This behavior was not observed in

males. Muscle and liver of R. sapo females (pre- and

post-) were dominated by tri-, penta- and hexa-chlori-

nated congener groups while penta-, hexa- and hepta-

were accumulated by males (Fig. 3). In mesenteric fat of

post-spawning organisms and pre-spawning gonads a

predominance of penta-, hexa- and hepta-congener

groups was observed. When PCB values were expressed

on ng/g lipid, the muscle tissues of pre-spawning females

of both fish species showed the highest concentrations,

being R. sapo 2X-fold higher than O. jenynsi, (Table 2).

Tissues of both fish species showed a similar congener

group pattern when they were expressed either in ng/g

wet wt. or ng/g lipid wt. (Fig. 4). Differences between fish

species were noted regarding lower chlorinated congen-

ers. Thus, congeners 49 and 52 were detected in high

concentration in muscle and liver tissues of O. jenynsi,

while congener 18 in muscle and liver of R. sapo pre-

spawning females (Table 3).

O. jenynsi/grass shrimp BMF had a mean value of

18.7. Congeners 44, 52 and 151 showed the highest BMF

values.

4. Discussion

4.1. Macrophytes

It has been shown that macrophytes are involved in

the uptake, bioconcentration and movement of orga-

nochlorine contaminants in aquatic ecosystems as well

cycling of essential nutrients and increasing sedimenta-

tion of suspended particles within macrophyte beds

(Lovett-Doust et al., 1994; Biernacki et al., 1995b).

Painter (1990) found that PCB levels could be 3–4

times higher in plants than in sediments and 6000–9000

times higher in plants than in the water around them (on

Fig. 2. Global distribution of PCB from 3 to 8 isomers expressed as relative abundance in macrophytes collected in both stations from

Los Padres Lake, Argentina. Bul: bulrush; f.loo: false loosestrife.

M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122 1117

a dry wt. basis). In our work, bulrush (S. californicus), a

littoral submerged macrophyte, was exposed to signifi-

cant amount of PCBs in situ, reflecting sediment, water

and air loads, whereas false loosestrife (Ludwigia sp.), a

rooted floating-leaved macrophyte, mainly exposed to

water and air load. False loosestrife accumulated higher

PCB levels (wet wt.) than bulrush, emphasizing the im-

portance of lipid content as a determinant of PCB

concentration in macrophytes.

Total PCB concentrations in both macrophytes from

Station 1 were higher than those from Station 2, show-

ing that the former would receive PCBs washed down

from upstream areas. Gonz�aalez Sagrario (1998) alsofound differences of this nature in the same region for

organochlorine pesticides. The relative enrichment of

the lower chlorinated congeners (3 and 4 Cl) in bulrush

from Station 2 could be a consequence of: firstly, higher

chlorinated congeners are more hydrophobic and per-

sistent than lower ones and tend to accumulate in sedi-

ments while low chlorinated congeners are more likely to

be transferred in water column and be transported to

Station 2. Secondly, bulrush roots reach up to 40–50 cm

of depth being able to uptake tri- and tetra-chlorinated

congeners as a product of reductive dechlorination of

the more highly chlorinated congeners because of anoxic

characteristics of this station.

Although it has been demonstrated the existence of

various Phase I and Phase II detoxification enzymes in

aquatic macroalgae and terrestrial plants (Trapp et al.,

1990; Pflugmacher et al., 1999), no metabolism of PCB

has been recorded in vascular aquatic plants. The PCB

loads in aquatic macrophytes constitute the main routes

Table 3

Concentrations of the different PCB congeners on lipid basis (ng/g lipid wt.) in organisms from Los Padres Lake, Argentina

IUPAC # S. californicusa Ludwigia sp.a P. argentinus O. jenynsib R. sapob

S1 S2 S1 S2 Ovary Liver Muscle Ovary Liver Muscle

Tri-

18 0.3 1.3 n.d. 0.1 1.2 n.d. 24.3 n.d. n.d. 138.2 1338.6

31 0.5 0.2 n.d. 0.1 3.0 13.1 10.1 50.6 n.d. 15.6 795.3

28 n.d. 0.3 n.d. n.d. 6.2 n.d. n.d. n.d. n.d. n.d. n.d.

Tetra-

52 n.d. 0.1 n.d. n.d. 3.6 45.2 40.0 231.5 7.2 11.8 148.8

49 n.d. 0.3 n.d. n.d. n.d. 12.3 108.5 157.3 n.d. 5.4 185.8

47 n.d. n.d. n.d. n.d. 0.8 n.d. n.d. n.d. 6.2 36.0 n.d.

44 n.d. 0.3 n.d. 0.1 1.0 13.7 11.5 66.3 n.d. 21.5 n.d.

66 0.1 <0.1 0.2 0.1 7.2 32.9 13.4 56.2 8.3 14.0 79.5

Penta-

101 0.4 0.1 0.6 0.4 21.6 155.4 45.3 210.1 42.4 41.9 301.6

99 0.2 <0.1 0.5 0.1 8.3 82.0 19.2 75.3 21.7 18.8 147.2

87 0.3 <0.1 0.2 0.2 9.9 40.7 16.4 82.0 14.9 16.7 97.6

110 0.9 0.1 0.7 0.7 41.3 206.1 61.5 146.1 57.6 62.4 276.4

118 0.3 0.1 1.6 0.3 32.7 220.0 53.4 221.4 76.5 64.0 443.3

105 0.1 <0.1 0.6 0.2 13.9 62.6 18.6 77.5 25.6 22.0 138.6

Hexa-

149 0.2 <0.1 0.4 n.d. 14.3 153.6 39.1 179.8 38.2 34.4 255.1

151 0.1 <0.1 0.2 0.3 0.9 72.2 18.4 56.2 9.5 63.4 100.0

153 0.3 <0.1 4.5 0.4 59.3 610.6 135.6 542.7 224.6 166.1 1603.2

156 <0.1 <0.1 0.3 <0.1 2.2 18.6 4.1 18.0 12.6 4.8 45.7

138 0.9 <0.1 3.5 0.6 61.7 519.2 125.3 518.0 180.2 135.0 1106.3

Hepta-

180 0.1 <0.1 2.3 0.2 19.1 292.8 61.5 246.1 95.5 82.8 918.9

170 <0.1 <0.1 1.1 0.1 10.4 144.4 27.1 113.5 51.0 27.4 203.2

Octa-

199 <0.1 <0.1 0.3 <0.1 2.8 38.9 8.1 29.2 11.0 9.1 81.1

195 n.d. <0.1 0.1 n.d. 0.6 13.5 2.6 12.4 3.5 3.8 22.1

194 n.d. <0.1 0.2 <0.1 1.5 27.6 4.9 n.d. 8.5 6.5 76.4

a ng/g wet wt.b pre-spawning female.

1118 M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122

for the introduction of these compounds into the food

web, when they are consumed as live plants by herbi-

vores or as detritus by detritivores.

4.2. Animal biota

Grass shrimp, in Los Padres Lake, lives associated

with bulrush and it could obtain PCBs from water, in-

gestion of detritus and predation over periphytic cover of

macrophytes and small invertebrates. Its relatively short

life cycle, as well as the known lower bioaccumulation

capacity of crustaceans, comparing with that reported by

Porte and Albaig�ees (1993) for mollusc and fish for or-ganic contaminants, such as PCBs, would be two factors

that justify the low PCB levels found in grass shrimp.

Nevertheless, Porte and Albaig�ees (1993) have recognizedthe ability of crustaceans under chronic exposure to aryl

pollutants, to develop or induce their mixed function

oxygenases (MFO) enzymatic system, for biotransfor-

mating PCBs. They have demonstrated that the rate of

metabolic activities was in the following order: crab >tuna > mullet > mussel. The levels of total PCBs foundin grass shrimp were comparatively lower than those in

giant red shrimp from Suruga bay, Japan (Lee et al.,

1997) and in P. pugio from Purvis Creek, USA (Maruya

and Lee, 1998). In our work, congeners 138, 153, 110, 118

and 101 represent 64% of the total PCBs found in grass

shrimp. Excluding 110 and 101, the rest of congeners

share the recalcitrant 4-40-substitution or no vicinal H-

atoms in both aromatic rings and therefore would be

accumulated and not metabolized.

Body burden of PCBs in O. jenynsi could arise from

suspended particles and its main prey, grass shrimp

while in R. sapo can arise from direct contact with sed-

iments contaminated, sediment ingestion and food chain

routes. Muscle tissue of R. sapo showed higher PCB

levels than O. jenynsi likely due to the fact that R. sapo

was exposed to higher PCB loads.

PCB concentrations in gonads of R. sapo varied

concomitantly with their lipid levels, though this fact

was not found in muscle, reflecting a non-equilibrium

situation in which its lipid levels have changed more

rapidly than PCB load (Kelly and Campbell, 1994).

Moreover, in these relatively lean tissues it can be

speculated that proteins and other non-lipid cellular

components contribute substantially to chemical parti-

tioning (Bertelsen et al., 1998).

The growth of fish ovaries prior to spawning and the

increase of their lipid content, would enhance the ca-

pacity for the PCB uptake. This behavior would justify

the high concentration found in pre-spawning ovaries of

both fish species. The low PCB levels found in post-

spawning ovaries of R. sapo would be a consequence of

eggs releasing during spawning, which have large

quantities of lipid soluble contaminants. This detoxifi-

cation activity would be more important than that car-

ried out by MFOs in the liver (Von Westernhagen et al.,

1995).

By the other hand, since testes constitute a minor

fraction of total body of fish and have a low lipid

Fig. 3. Distribution of PCB congener groups in gonads, liver,

muscle and mesenteric fat of R. sapo organisms with different

gonadal development, expressed in ng/g wet wt. pre-fem: pre-

spawning female; post-fem: post-spawning female; pre-male:

pre-spawning male; post-male: post-spawning male.

M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122 1119

content with respect to the ovary, it would be justified

the low detoxification capacity carried out by males

(Von Westernhagen et al., 1995). As a result, generally

the PCB tissue burdens are lower in females than in

males (Lanfranchi et al., 1998).

The same congener group patterns found in liver and

muscle of R. sapo organisms would indicate that muscle

tissue reflects in reliable way the PCB uptake by diet,

because of the low detoxification rate of this tissue.

The absence of mesenteric fat in pre-spawning R.

sapo organisms would indicate that this tissue has been

used as energetic source during gonad maturation pe-

riod. As a result, large amounts of PCBs would be re-

leased into the bloodstream and reach the other targets

organs, such as gonads, liver or muscle tissue. In fact,

higher PCB levels were found in pre-spawning tissues of

R. sapo females compared with post-spawning ones.

Mesenteric fat and pre-spawning ovary showed the same

congener group pattern, being hexa > penta > hepta.Since males did not accumulate high lipid content in pre-

spawning gonads, the distribution of PCB congeners

from mesenteric fat, was mainly delimited to muscle and

liver tissues.

The congener group distribution among tissues of

both fish species, would be mainly determined by the

lipid composition. Thus, mesenteric fat rich in non-polar

lipids have largely accumulated hydrophobic congeners

(penta-, hexa- and hepta) with Kow > 6. According to,muscle tissue, with low lipid content, usually enriched by

polar lipids accumulated the highest levels of tri- and

tetra-congener groups compared with other tissues.

Our study showed that the distribution of PCB

congeners in the lake did not occur in a predictable

manner, since there is no indication of an increase in the

proportion of higher chlorinated congeners in higher

trophic levels.

BMF for predation–prey relationship O. jenynsi–

grass shrimp had a mean value of 18.7. Maruya and Lee

(1998) have reported mean BMF values in the order of

12 for the shrimp–mullet couple.

Polychlorinated biphenyls uptake and dietary ab-

sorption efficiency have been reported to be essentially

equivalent for Cl2–Cl10 congener groups (Niimi, 1996).

PCB elimination rates in fish were found to decrease

with increasing number of chlorine while for less chlo-

rinated PCB elimination rates decrease with increasing

ortho-chlorine substitution (Niimi and Oliver, 1983).

Accordingly, in our work congener 44, 49 and 52,

which have ortho-chlorine substitution in both aromatic

rings, showed the highest values between low congener

groups and the BMF values of congener 44 and 52

were the highest. About to congener 49, the BMF value

was not determined because of in grass shrimp was not

detected.

Fig. 4. Distribution of PCB congener groups in ovary, liver and muscle in pre-spawning females of both fish species, expressed in ng/g

lipid wt.

1120 M.A. Gonz�aalez Sagrario et al. / Chemosphere 48 (2002) 1113–1122

Some penta- and hexa-chlorinated congeners, lack-

ing 4,40-chlorinated substitution like congener 151, were

found to be remarkably low in crustacean (Duinker

et al., 1983). In our work, congener 151 was the lowest

value found in grass shrimp among the highly chlori-

nated congeners and the BMF value was found among

the highest although the level of this congener in O.

jenynsi was relatively low.

5. Conclusions

First results on the PCB levels in freshwater organ-

isms from Los Padres Lake are presented. The bio-

concentration process in macrophytes appears to be

influenced by a number of factors including species, lipid

content and the area where they live as well as physical

conditions of the lake.

There was a relationship between the PCB concen-

trations in the animal biota and either trophic level or

lipid content of the organisms. Our results indicate that

the patterns of relative abundance of PCB congener

groups did not change among animal biota. The highest

concentrations were found for penta- and hexa-chlori-

nated congeners, consistent with commercial mixture of

Aroclor 1254 used in this region.

PCB concentrations in fish tissues varied with the

species and the gonadal development. Pre-spawning

ovaries of both fish species showed high PCB levels, as a

result of growth and increase of lipid content priori to

spawning. On the other hand, during spawning an im-

portant load of highly chlorinated congeners has been

lost, becoming in a great detoxification way conducted

by females.

Biomagnification of the most PCB congeners has

occurred, even though they did not clearly displayed an

increasing trend with increasing logKow.In order to have a more complete comprehension of

the PCB behavior in Los Padres Lake, it would be

necessary to extend sampling to other matrix, like bot-

tom sediments, for understanding the precise nature of

the recycling process in aquatic systems.

Acknowledgements

The authors thank Mrs M�oonica Thomas for draftingthe map. All analytical work was conducted at Envi-

ronmental and Resources Studies Program, Trent Uni-

versity, Peterborough, Ontario, Canad�aa. We thank Dr.C.D. Metcalfe for the high professional standards and

attention to detail in overseeing the analyses. This study

was supported by grants (PMT-PICT 0363 Prest. BID

802/OC-AR, EXA 072/97 and EXA 105/97) from

CONICET/Agency and SIyDT (Secretar�ııa de Investi-

gaci�oon y Desarrollo Tecnol�oogico) of Mar del PlataUniversity, respectively.

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