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Some heavy metals in sprat (Sprattus sprattus) and herring (Clupea harengus) from the inner Oslofjord
Aquaculture, 2 (1973) 17-22 @ Elsevier Scientific Publishing
17 Company,
Amsterdam
- Printed
in The Netherlands
SOME HEAVY METALS IN SPRAT (Spruttus sprattus) AND HERRING (C&pea harengus) FROM THE INNER OSLOFJORD
A.T. ANDERSEN,
A. DOMMASNES
and I.H. HESTHAGEN
University of Oslo, Laboratory for Marine Zoology and Marine Chemistry, Oslo 3 (Norway) * (Received
January
18, 1973)
As part of a base-line study initiated in the Oslofjord, Norway, concentrations of copper, zinc, cadmium and lead have been measured in age-groups 0 and 1 sprat, Sprktus spruttus (L.) and in O-group herring, Clupea harengus L. Some values for the concentrations of these metals in the sea-water are also given, and the results are briefly discussed.
INTRODUCTION Through the awareness of possible hazards caused by high concentrations of heavy metals in marine organisms in recent years, the assessment of heavy metals in these organisms has become necessary to enable us to draw a certain base-line for later monitoring. It is in most cases too late to establish the real base-line, i.e. the naturally occurring concentrations of heavy metals in the organisms, particularly in a relatively closed fjord like the Oslofjord, which for a long time has served as the main recipient for domestic sewage from the capital of Norway as well as for effluents from a number of industries. The present paper is a contribution to this base-line study, trying to ascertain the level of heavy metals in the sprat and herring in the &lofjord. The sprat is by far the most important commercial fish in the Oslofjord, and it is used almost exclusively for canning. Mixed with the commercial catches of sprat, there seems to be a large proportion of young herring of similar size, schooling together with the sprat. These can only be separated from the sprat by thorough examination and are consequently sold and processed as ‘sprat’. In the present work sprat and herring have been separated before analysis. * P.O.
Box 1064. Blindern.
18 MATERIAL
AND METHODS
The fish for the present investigation was collected from five localities in the inner Oslofjord (Fig. 1) with a hand-hauled shore seine. The samples consist of 510 sprat of which 498 were identified as belonging' to the age-group 0 and 12 to the age-group 1, and 2 19 herring, all being of age-group 0. The fish was stored frozen until they were prepared for analysis. After identification of species and length measurement, each fish was decapitated, eviscerated and the tail was cut off. The entrails were removed in order to prevent possible contamination by the stomach
Fig. 1. Map of the inner Oslofjord with sampling localities. Water samples were obtained from the localities designated by capital letters A-D.
contents, but at the same time the other viscera were removed. When used for human consumption, the fish is eaten complete with skin and bones as well as entrails, but prior to processing, the sprat is kept in a seine for a couple of days to rid itself of the stomach contents. Thus the liver and certain other organs known to concentrate certain metals (cf e.g. Truhaut and Boudene, 1954), are eaten when the sprat is used as food for man. It was, however, not feasible without considerable time expenditure to remove only the stomach in the present instance, and Table 1 is likely to present minimum rather than maximum values.
1
Herring
Rambergiiy RambergGy
Sprat
RambergGy BorGy G&By Lang&a Storskjaer
BorGy
Locality
2NOV 2 NOV 26 SEP 26 SEP 22AUG
23 AUG 2NOV 2 NOV 2 NOV 2NOV
Date
6-9 6-9 6-9 7-9 6-8
4-6 4-6 >9 4-6 >9
Age group
Length group (cm)
85 49 47 22 16
196 220 10 82 2 80.2 80.3 79.8 79.3 81.0
80.8 80.5 80.0 80.1 80.7
(%I
Water contents
in the inner Oslofjord,
No. of fish analysed
of Cu, Zn, Cd and Pb in sprat and herring
Species
Concentrations
TABLE 1972
3.5 3.6 4.3 3.4 7.2
7.0 6.2 3.5 8.5 2.6
cu
140 120 120 95 120
140 85 145 85 210
Zn
Heavy metal cont.,
autumn
0.2 <0.2 <0.2 <0.2 <0.2
0.2 0.7 <0.2 <0.2 <0.2
Cd
3.2 4.0 12.2 7.2 8.6
7.4 7.2 <0.3 21.8 4.1
Pb
pg/g dry weight
20 The fish were pooled together in groups according to length and species. Each group or sample was dried at 100 “C to constant weight in acid-cleaned Pyrex glass beakers. The dried samples were homogenised in an electric grinder, and a sample of 250 mg was used for each analysis. This was wet-ashed in a mixture of 1 ml cont. sulphuric acid, 5 ml cont. nitric acid and 5 ml 30% hydrogen peroxide on a hot plate. When the solution became clear and the white fumes of sulphuric acid started to appear, the process was stopped and the samples were allowed to cool. The volume was then adjusted to 50 ml with double distilled water and the acidity was adjusted to approximately pH 3 with NaOH and H, S04. The volume was thereafter adjusted to 100 ml and extraction was made with 5 ml 1% APCD and 10 ml MIBK. The fractions were allowed to separate for lo- 15 min. Suitable standards were prepared under the same conditions. A Perkin Elmer 290 B atomic absorption spectrophotometer was used for all determinations. For the determination of copper and zinc the solution was aspired into the flame, whereas lead and cadmium were determined by employing the sampling boat technique. RESULTS AND DISCUSSION The results are presented in Table 1, where the heavy metal concentrations are given as pg/g of dried material. Length frequency data and scale readings for the sprat indicate that both age-groups 0 and 1 occurred in the samples, while only age-group 0 herring was caught. Concentrations of all the metals reveal conspicuous differences between the age-groups 0 and 1 Sprat.
Copper If we first have a look at the values for sprat, it is immediately evident that copper content in the O-group is higher than in the l-group. The concentrations in the age-group 0 for the three samples are fairly equal. The same is true also in the age-group 1 sprat. We know that the copper concentrations in the sea-water at nearby localities have been found to be moderately high (Table 2). A reasonable explanation for the high contents of copper in O-group sprat as compared to l-group is therefore that the younger individuals are more stationary than the older ones. The @group sprat is probably feeding constantly on food organisms from a locality of relatively high copper contents in the water and has not yet had the opportunity to get into cleaner water and rid themselves of excess contents of copper and other heavy metals acquired at the more polluted locality where they spent their first months.
21 TABLE
2
Concentrations of Zn, Cu, Cd and Pb in the inner Oslofjord. The values represent the mean concentration for two samples at each locality, one in 0 m and one in 5 m depth (from El-Rayis, unpublished data) Locality (see Fig. 1)
A B C D
Date
26 26 26 25
OCT OCT OCT OCT
Heavy metal cont.,
1972 1972 1972 1972
pg/liter
sea-water
Zn
cu
Cd
Pb
72.5 66.0 52.6 40.6
9.1 8.8 10.4 8.4
0.83 0.74 0.92 0.67
1.2 2.8 2.4 I.0
Herring from four of the stations all show similar copper content to that found in the age-group 1 sprat. A reasonable conclusion to be drawn from this is that the young herring is also relatively wide-ranging and therefore can keep the copper concentrations in their body at a lower level. The somewhat higher copper contents in the herring from the fifth locality just outside the narrow entrance to the inner Oslofjord ~ Storskjaer - is probably a consequence of the fact that this sample contained relatively smaller individuals. The copper concentration in the water near Storkjaer is not conspicuously higher than further towards the head of the fjord (Table 2, D). Zinc
Zinc concentrations in sprat show a tendency opposite to that for copper; concentrations in the l-group are considerably higher than in the O-group. Also herring has a relatively high zinc concentration in all the samples, though somewhat between that of O-group and l-group sprat. This corresponds with the size of the O-group herring, which is intermediate of the two groups of sprat. This increase of zinc in the body with growth can be explained by the high concentrations of zinc in the seawater in the whole inner Oslofjord (cf: Table 2), as compared to the other heavy metals treated in the present work. Cadmium
The cadmium values show very little O-group sprat from Rambergoy, the sample contained 0.7 pg/g dry weight, sprat and herring - contained 0.2 pg/g agreement with the relatively low level (Table 2).
variation except for one locality closest to the whereas all the other dry weight or less. This of cadmium in the inner
sample of city. This samples is in good Oslofjord
22 Lead Here again we find a pattern like that for copper. The contents of lead is lower in the l-group sprat than in the O-group. The explanation may also be the presumably more stationary habits of the youngest sprat. Another interesting feature is the apparent difference between the values for Rambergoy and Borijy in November. Boroy is situated in a shallow and relatively closed basin, and just at the edge of this basin runs a heavily trafficked highway. Lead contamination of sea-water and marine organisms have been reported to originate from the exhaust of automobiles burning lead fuel (Anon., 197 1). ACKNOWLEDGEMENT We are indebted to Mr. Osman-El-Rayis, Institutt for marinbiologi og limnologi, University of Oslo, for kindly providing us with the data on heavy metal concentrations in the sea-water. REFERENCES Anon. (1971) Lead in the sea. Mar. Pollut. Bull., 2(l) 8. Truhaut, R. and Boudene, C. (1954) Enquiries into the fate of cadmium in the body poisoning, of special interest to industrial medicine. Arh. Hig. Rada, 5, 19-32.
during
17 Company,
Amsterdam
- Printed
in The Netherlands
SOME HEAVY METALS IN SPRAT (Spruttus sprattus) AND HERRING (C&pea harengus) FROM THE INNER OSLOFJORD
A.T. ANDERSEN,
A. DOMMASNES
and I.H. HESTHAGEN
University of Oslo, Laboratory for Marine Zoology and Marine Chemistry, Oslo 3 (Norway) * (Received
January
18, 1973)
As part of a base-line study initiated in the Oslofjord, Norway, concentrations of copper, zinc, cadmium and lead have been measured in age-groups 0 and 1 sprat, Sprktus spruttus (L.) and in O-group herring, Clupea harengus L. Some values for the concentrations of these metals in the sea-water are also given, and the results are briefly discussed.
INTRODUCTION Through the awareness of possible hazards caused by high concentrations of heavy metals in marine organisms in recent years, the assessment of heavy metals in these organisms has become necessary to enable us to draw a certain base-line for later monitoring. It is in most cases too late to establish the real base-line, i.e. the naturally occurring concentrations of heavy metals in the organisms, particularly in a relatively closed fjord like the Oslofjord, which for a long time has served as the main recipient for domestic sewage from the capital of Norway as well as for effluents from a number of industries. The present paper is a contribution to this base-line study, trying to ascertain the level of heavy metals in the sprat and herring in the &lofjord. The sprat is by far the most important commercial fish in the Oslofjord, and it is used almost exclusively for canning. Mixed with the commercial catches of sprat, there seems to be a large proportion of young herring of similar size, schooling together with the sprat. These can only be separated from the sprat by thorough examination and are consequently sold and processed as ‘sprat’. In the present work sprat and herring have been separated before analysis. * P.O.
Box 1064. Blindern.
18 MATERIAL
AND METHODS
The fish for the present investigation was collected from five localities in the inner Oslofjord (Fig. 1) with a hand-hauled shore seine. The samples consist of 510 sprat of which 498 were identified as belonging' to the age-group 0 and 12 to the age-group 1, and 2 19 herring, all being of age-group 0. The fish was stored frozen until they were prepared for analysis. After identification of species and length measurement, each fish was decapitated, eviscerated and the tail was cut off. The entrails were removed in order to prevent possible contamination by the stomach
Fig. 1. Map of the inner Oslofjord with sampling localities. Water samples were obtained from the localities designated by capital letters A-D.
contents, but at the same time the other viscera were removed. When used for human consumption, the fish is eaten complete with skin and bones as well as entrails, but prior to processing, the sprat is kept in a seine for a couple of days to rid itself of the stomach contents. Thus the liver and certain other organs known to concentrate certain metals (cf e.g. Truhaut and Boudene, 1954), are eaten when the sprat is used as food for man. It was, however, not feasible without considerable time expenditure to remove only the stomach in the present instance, and Table 1 is likely to present minimum rather than maximum values.
1
Herring
Rambergiiy RambergGy
Sprat
RambergGy BorGy G&By Lang&a Storskjaer
BorGy
Locality
2NOV 2 NOV 26 SEP 26 SEP 22AUG
23 AUG 2NOV 2 NOV 2 NOV 2NOV
Date
6-9 6-9 6-9 7-9 6-8
4-6 4-6 >9 4-6 >9
Age group
Length group (cm)
85 49 47 22 16
196 220 10 82 2 80.2 80.3 79.8 79.3 81.0
80.8 80.5 80.0 80.1 80.7
(%I
Water contents
in the inner Oslofjord,
No. of fish analysed
of Cu, Zn, Cd and Pb in sprat and herring
Species
Concentrations
TABLE 1972
3.5 3.6 4.3 3.4 7.2
7.0 6.2 3.5 8.5 2.6
cu
140 120 120 95 120
140 85 145 85 210
Zn
Heavy metal cont.,
autumn
0.2 <0.2 <0.2 <0.2 <0.2
0.2 0.7 <0.2 <0.2 <0.2
Cd
3.2 4.0 12.2 7.2 8.6
7.4 7.2 <0.3 21.8 4.1
Pb
pg/g dry weight
20 The fish were pooled together in groups according to length and species. Each group or sample was dried at 100 “C to constant weight in acid-cleaned Pyrex glass beakers. The dried samples were homogenised in an electric grinder, and a sample of 250 mg was used for each analysis. This was wet-ashed in a mixture of 1 ml cont. sulphuric acid, 5 ml cont. nitric acid and 5 ml 30% hydrogen peroxide on a hot plate. When the solution became clear and the white fumes of sulphuric acid started to appear, the process was stopped and the samples were allowed to cool. The volume was then adjusted to 50 ml with double distilled water and the acidity was adjusted to approximately pH 3 with NaOH and H, S04. The volume was thereafter adjusted to 100 ml and extraction was made with 5 ml 1% APCD and 10 ml MIBK. The fractions were allowed to separate for lo- 15 min. Suitable standards were prepared under the same conditions. A Perkin Elmer 290 B atomic absorption spectrophotometer was used for all determinations. For the determination of copper and zinc the solution was aspired into the flame, whereas lead and cadmium were determined by employing the sampling boat technique. RESULTS AND DISCUSSION The results are presented in Table 1, where the heavy metal concentrations are given as pg/g of dried material. Length frequency data and scale readings for the sprat indicate that both age-groups 0 and 1 occurred in the samples, while only age-group 0 herring was caught. Concentrations of all the metals reveal conspicuous differences between the age-groups 0 and 1 Sprat.
Copper If we first have a look at the values for sprat, it is immediately evident that copper content in the O-group is higher than in the l-group. The concentrations in the age-group 0 for the three samples are fairly equal. The same is true also in the age-group 1 sprat. We know that the copper concentrations in the sea-water at nearby localities have been found to be moderately high (Table 2). A reasonable explanation for the high contents of copper in O-group sprat as compared to l-group is therefore that the younger individuals are more stationary than the older ones. The @group sprat is probably feeding constantly on food organisms from a locality of relatively high copper contents in the water and has not yet had the opportunity to get into cleaner water and rid themselves of excess contents of copper and other heavy metals acquired at the more polluted locality where they spent their first months.
21 TABLE
2
Concentrations of Zn, Cu, Cd and Pb in the inner Oslofjord. The values represent the mean concentration for two samples at each locality, one in 0 m and one in 5 m depth (from El-Rayis, unpublished data) Locality (see Fig. 1)
A B C D
Date
26 26 26 25
OCT OCT OCT OCT
Heavy metal cont.,
1972 1972 1972 1972
pg/liter
sea-water
Zn
cu
Cd
Pb
72.5 66.0 52.6 40.6
9.1 8.8 10.4 8.4
0.83 0.74 0.92 0.67
1.2 2.8 2.4 I.0
Herring from four of the stations all show similar copper content to that found in the age-group 1 sprat. A reasonable conclusion to be drawn from this is that the young herring is also relatively wide-ranging and therefore can keep the copper concentrations in their body at a lower level. The somewhat higher copper contents in the herring from the fifth locality just outside the narrow entrance to the inner Oslofjord ~ Storskjaer - is probably a consequence of the fact that this sample contained relatively smaller individuals. The copper concentration in the water near Storkjaer is not conspicuously higher than further towards the head of the fjord (Table 2, D). Zinc
Zinc concentrations in sprat show a tendency opposite to that for copper; concentrations in the l-group are considerably higher than in the O-group. Also herring has a relatively high zinc concentration in all the samples, though somewhat between that of O-group and l-group sprat. This corresponds with the size of the O-group herring, which is intermediate of the two groups of sprat. This increase of zinc in the body with growth can be explained by the high concentrations of zinc in the seawater in the whole inner Oslofjord (cf: Table 2), as compared to the other heavy metals treated in the present work. Cadmium
The cadmium values show very little O-group sprat from Rambergoy, the sample contained 0.7 pg/g dry weight, sprat and herring - contained 0.2 pg/g agreement with the relatively low level (Table 2).
variation except for one locality closest to the whereas all the other dry weight or less. This of cadmium in the inner
sample of city. This samples is in good Oslofjord
22 Lead Here again we find a pattern like that for copper. The contents of lead is lower in the l-group sprat than in the O-group. The explanation may also be the presumably more stationary habits of the youngest sprat. Another interesting feature is the apparent difference between the values for Rambergoy and Borijy in November. Boroy is situated in a shallow and relatively closed basin, and just at the edge of this basin runs a heavily trafficked highway. Lead contamination of sea-water and marine organisms have been reported to originate from the exhaust of automobiles burning lead fuel (Anon., 197 1). ACKNOWLEDGEMENT We are indebted to Mr. Osman-El-Rayis, Institutt for marinbiologi og limnologi, University of Oslo, for kindly providing us with the data on heavy metal concentrations in the sea-water. REFERENCES Anon. (1971) Lead in the sea. Mar. Pollut. Bull., 2(l) 8. Truhaut, R. and Boudene, C. (1954) Enquiries into the fate of cadmium in the body poisoning, of special interest to industrial medicine. Arh. Hig. Rada, 5, 19-32.
during