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Monitoring metals in marine animals
Monitoring Metals in Marine Animals Routbe momttor~ of heavy metals in lish and
North Sea and the various distant-water grounds fished by boats landing in England and Wales. The deep-water some bivalves, but these are not an indication of likely samples are particularly useful, since they serve as c-oueeutmt~us in fimtlJh from the same areas. controls for the inshore samples and provide data on The co-operative monitoring programme for organo- concentrations found in animals away from the immechlorine pesticide residues and PCBs in marine fish diate influence of polluting discharges. undertaken by the Department of Agriculture and All samples are analysed for cadmium, chromium, Fisheries for Scotland and the Ministry of Agriculture, copper, lead, mercury and zinc, in addition to the organoFisheries and Food has already been described (Holden chlorine pesticides and PCB residues referred to in the and Portman, 1970); this report included a brief des- previous report. Usually, both muscle and livers of fish cription of the special investigations undertaken in con- are examined; each sample consists of 10 fish from nection with the Irish Sea bird kill which took place which muscle tissue is examined individually. The bulked in 1969. The results of the detailed studies undertaken livers are homogenized and sub-samples are taken for by the two departments following that incident have analysis. The muscle analysis is made on a homogenate now been published (NERC, 1971) and demonstrate prepared from a fillet cut from the centre length of the the usefulness of regular monitoring of fish and shell- fish, i.e. from immediately behind the head to the tail fish for the presence of organo-chlorine pesticide and and down to the backbone. The skin and larger bones are removed before homogenizing. There is some PCB residues around the United Kingdom. In the course of the last year, there has been an evidence of uneven metal distribution in the muscle tissue increasing awareness in the scientific press of the need and of differences between muscle, bone and skin, and to establish the distribution of heavy metals, particularly this procedure eliminates the danger of sampling errors mercury and cadmium, in marine species exploited com- within the individual fish. mercially. Soon after the bird kill incident, the analytical Bivalve shellfish are removed from the shell and the programme of the MAFF laboratory at Burnham-on- combined meats of 20-25 individuals are homogenized. Crouch was expanded to include the analysis of fish and Small Crustacea such a shrimps and shore crabs are shellfish samples for several metals. After analysis of bulked whole and homogenized, but only the edible a long series of samples, it now seems opportune to out- portions of larger species axe analysed; usually the claw, line the scheme of the work in progress at this laboratory. tail and brown body meat of each individual is analysed Details of this work have not been published previously, separately. because it is necessary to obtain an overall picture of Measurement of the metal concentrations is made by the distribution of these metals before the significance atomic absorption spectrophotometry after wet-ashing of the results can be ascertained. By adopting such an of a sub-sample of homogenate, using concentrated nitric, approach, the difficulties which arise from making a or nitric and sulphuric acids. Since the primary interest judgement on insufficient information can be avoided. of the department is to determine the metals present in Thus, the levels of mercury found in tuna, which fish and shellfish reaching the human consumer, results originally caused considerable concern in the United are normally expressed on a wet weight basis. States, now do not appear to be abnormal and are probably unrelated to industrial pollution. This conclusion is supported by Hammond (1971) who demonstrated that Results man's activities have contributed less than one per cent of The detailed results of our surveys to date are in the the total mercury in the marine environment, and most course of preparation for a series of reports to be pubof it in the coastal regions; tuna are essentially deep- lished in the autumn. Most of the common species of water fish. fish (cod, whiting, plaice, mackerel, herring, haddock, dabs, coalfish, skate, flounders, lemon sole and dover Methods sole) from estuaries, coastal waters, the North Sea, Irish The monitoring programme undertaken by MAFF to Sea, English Channel and distant-water grounds (Barents determine the levels of heavy metals in marine animals Sea, Iceland, Norway and Greenland) have, subject to (particularly food fish and shellfish) started with the availability in the various areas, been sampled and examination of samples collected since July 1969. About analysed for all six metals. Samples of all the common half of these samples have been collected as part of the shellfish (cockles, mussels, oysters, clams, escallops, routine sampling programme of coastal fish stocks. For queens, shrimps, Norway lobster, lobster, crab, limpets this purpose, 10 specimens of cod, whiting, plaice, and winkles) have also been collected from estuaries and mackerel and herring were obtained from nine repre- coastal waters where they occur. Other species of marine sentative ports around England and Wales on a twice- animals have been collected in areas of special interest. The results obtained from fish samples show that there yearly basis. Samples of shore crabs, mussels, shrimps and other edible shellfish are collected from most of the are comparatively small differences in the concentrations English and Welsh estuaries. In addition, samples are of metals between individuals of the same species from collected of the main commercial species of fish from the the same area--frequently less than five-fold between shdm~h from British waters indicates high levels in
157
the extremes. There is also very little difference in the mean concentrations of most metals found in the different species taken from an area, although the mean concentrations found in herring and mackerel are consistently higher than in other species from the same area. The results obtained indicate that there are differences in the concentrations of metals found in fish from different areas; for example, fish from the Southern Bight of the North Sea usually contain more lead, zinc, copper and mercury than similar fish from the northern North Sea. The concentration of metals in the fish livers is generally found to be two to five times higher than in the muscle tissue. From the results obtained with shellfish it is clear that great care is required in interpreting the results. Generally, the concentrations are much higher than those found in fish. The range of concentrations found in a particular species from different areas, and even occasionally within the same area, is considerable and cannot always be attributed to man's polluting activities; very high levels in some areas appear to be due to natural run-off. There is also evidence that the occurrence of high metal concentrations in one species does not necessarily indicate pollution, since bivalves in general, and oysters in particular, are extremely efficient concentrators of metals from
Poll
Ministry o[ Agriculture, Fisheries and Food, Fisheries laboratory, Remembrance Avenue, Burnham-on-Crouch CMO 8HA, U.K. Hammond, A. L. (1971), Mercury in the environment: natural and human factors, Science, NY, 171 (3973), 788,9. Holden, A. V. and Portmann, J. E. (1970), Monitoring organochlorine residues, Mar. Poll. Bull., 1 (NS) (3), 4t-2, NERC (1971), The seabird wreck in the Irish Sea, Autumn, 1969, Natural Environment ResearCh Council PUblication, Series C, No. 4, 17.
on in Greek
A eo-otmmtlve Greek-American i n v u t i p a o n studies the effect of a sewage outfall on eutrophication in the eastern Mediterranean.
The Nuclear Research Centre "Democritus" is the main research institute in Greece. It has facilities for basic and applied research and for multidisciplinary investigations requiring mainly nuclear facilities. Of the 160 scientific personnel, 70 have postgraduate education. The centre is divided into several divisions and marine pollution studies are being pursued in tim Biology Division by the hydrobiology group, in collaboration with the Department of Oceanography of tM University of Washington, Seattle. The hydrobiology group (six people) is carrying out studies of marine productivity and the effect of pollution in the food chain. A study of marine fouling in oil polluted areas is also carried out by the group (Ignatiades and Becacos-Kontos, 1970). The unpolluted Saronicos Gulf has a low level of productivity and very small amounts of nutrients (BecacosKontos, 1968; Ignatiades and Becacos-Kontos, 1969). In recent years, serious problems of pollution were created by the new sewage outfall at Keratsini (Fig. 1) which introduces the sewage from Athens and its suburbs into the Saronicos Gulf. The Keratsini outfall has visibly affected the primary production in the upper Saronicos Gulf and in February and March, 1970, preliminary investigations of the effect of the Keratsini outfall on the chemistry and biology of the surrounding waters were made jointly with the scientists on the research vessel 158
sea water, and very great differences occur between the levels of accumulation in different, and even closely related, species. The concentration of specific metals may well be exhibited by a particular marine species and it is therefore essential that, when comparisons are made between different areas, the same species should be used. However, because certain species may concentrate specific metals, a general assessment of the metal concentrations in a particular area can only be made if several species from the same area are examined. Finally, the analyses carried out to date suggest that the concentrations of metals in shellfish cannot be used to predict the likely levels in pelagic or demersal fish from the same area. J. E. PORTMANN
Thompson, of the Department of Oceanography, University of Washington. The outfall studies were not a major objective of the Thompson cruise 47, but the cruise was designed to carry out intensive studies of the dynamics of marine biological production in a limited area. For these studies a system of rapid shipboard data acquisition and analysis was developed with further elaboration of the data immediately made possible by computer simulation models being used and developed on board the ship. An IBM 1130 computer with a Calcomp plotter for graphic display, and a Hewlett Packard digitizer and scanning unit to interrogate an array of sensors which measure environmental parameters, constitute the basic Thompson system. Using this system, it is possible to obtain synoptic maps of any parameter which can be measured continuously. The results of a mapping survey made on March 14, 1970 are shown in Figure 2a-d. High concentrations of phosphate, silicate and nitrate (Fig. 2a-c) surround the outfall, with very high gradients prevailing out to a distance of about 2 km. One effect of high nutrients on Mediterranean water is shown in Figure 2d where greatly enhance, d cMorophyll concentrations are shown also to correspond with the outfall. The diffusion of the effluent materials was restricted by light south winds, but nevertheless the effects were visible for a distance of at least 20 kin. To continue this preliminary investigation, a project is being set up in Greece under the International Biological Programme (~BP). The project will be centred in Democritus. The 1BP Integrated Research Programme
North Sea and the various distant-water grounds fished by boats landing in England and Wales. The deep-water some bivalves, but these are not an indication of likely samples are particularly useful, since they serve as c-oueeutmt~us in fimtlJh from the same areas. controls for the inshore samples and provide data on The co-operative monitoring programme for organo- concentrations found in animals away from the immechlorine pesticide residues and PCBs in marine fish diate influence of polluting discharges. undertaken by the Department of Agriculture and All samples are analysed for cadmium, chromium, Fisheries for Scotland and the Ministry of Agriculture, copper, lead, mercury and zinc, in addition to the organoFisheries and Food has already been described (Holden chlorine pesticides and PCB residues referred to in the and Portman, 1970); this report included a brief des- previous report. Usually, both muscle and livers of fish cription of the special investigations undertaken in con- are examined; each sample consists of 10 fish from nection with the Irish Sea bird kill which took place which muscle tissue is examined individually. The bulked in 1969. The results of the detailed studies undertaken livers are homogenized and sub-samples are taken for by the two departments following that incident have analysis. The muscle analysis is made on a homogenate now been published (NERC, 1971) and demonstrate prepared from a fillet cut from the centre length of the the usefulness of regular monitoring of fish and shell- fish, i.e. from immediately behind the head to the tail fish for the presence of organo-chlorine pesticide and and down to the backbone. The skin and larger bones are removed before homogenizing. There is some PCB residues around the United Kingdom. In the course of the last year, there has been an evidence of uneven metal distribution in the muscle tissue increasing awareness in the scientific press of the need and of differences between muscle, bone and skin, and to establish the distribution of heavy metals, particularly this procedure eliminates the danger of sampling errors mercury and cadmium, in marine species exploited com- within the individual fish. mercially. Soon after the bird kill incident, the analytical Bivalve shellfish are removed from the shell and the programme of the MAFF laboratory at Burnham-on- combined meats of 20-25 individuals are homogenized. Crouch was expanded to include the analysis of fish and Small Crustacea such a shrimps and shore crabs are shellfish samples for several metals. After analysis of bulked whole and homogenized, but only the edible a long series of samples, it now seems opportune to out- portions of larger species axe analysed; usually the claw, line the scheme of the work in progress at this laboratory. tail and brown body meat of each individual is analysed Details of this work have not been published previously, separately. because it is necessary to obtain an overall picture of Measurement of the metal concentrations is made by the distribution of these metals before the significance atomic absorption spectrophotometry after wet-ashing of the results can be ascertained. By adopting such an of a sub-sample of homogenate, using concentrated nitric, approach, the difficulties which arise from making a or nitric and sulphuric acids. Since the primary interest judgement on insufficient information can be avoided. of the department is to determine the metals present in Thus, the levels of mercury found in tuna, which fish and shellfish reaching the human consumer, results originally caused considerable concern in the United are normally expressed on a wet weight basis. States, now do not appear to be abnormal and are probably unrelated to industrial pollution. This conclusion is supported by Hammond (1971) who demonstrated that Results man's activities have contributed less than one per cent of The detailed results of our surveys to date are in the the total mercury in the marine environment, and most course of preparation for a series of reports to be pubof it in the coastal regions; tuna are essentially deep- lished in the autumn. Most of the common species of water fish. fish (cod, whiting, plaice, mackerel, herring, haddock, dabs, coalfish, skate, flounders, lemon sole and dover Methods sole) from estuaries, coastal waters, the North Sea, Irish The monitoring programme undertaken by MAFF to Sea, English Channel and distant-water grounds (Barents determine the levels of heavy metals in marine animals Sea, Iceland, Norway and Greenland) have, subject to (particularly food fish and shellfish) started with the availability in the various areas, been sampled and examination of samples collected since July 1969. About analysed for all six metals. Samples of all the common half of these samples have been collected as part of the shellfish (cockles, mussels, oysters, clams, escallops, routine sampling programme of coastal fish stocks. For queens, shrimps, Norway lobster, lobster, crab, limpets this purpose, 10 specimens of cod, whiting, plaice, and winkles) have also been collected from estuaries and mackerel and herring were obtained from nine repre- coastal waters where they occur. Other species of marine sentative ports around England and Wales on a twice- animals have been collected in areas of special interest. The results obtained from fish samples show that there yearly basis. Samples of shore crabs, mussels, shrimps and other edible shellfish are collected from most of the are comparatively small differences in the concentrations English and Welsh estuaries. In addition, samples are of metals between individuals of the same species from collected of the main commercial species of fish from the the same area--frequently less than five-fold between shdm~h from British waters indicates high levels in
157
the extremes. There is also very little difference in the mean concentrations of most metals found in the different species taken from an area, although the mean concentrations found in herring and mackerel are consistently higher than in other species from the same area. The results obtained indicate that there are differences in the concentrations of metals found in fish from different areas; for example, fish from the Southern Bight of the North Sea usually contain more lead, zinc, copper and mercury than similar fish from the northern North Sea. The concentration of metals in the fish livers is generally found to be two to five times higher than in the muscle tissue. From the results obtained with shellfish it is clear that great care is required in interpreting the results. Generally, the concentrations are much higher than those found in fish. The range of concentrations found in a particular species from different areas, and even occasionally within the same area, is considerable and cannot always be attributed to man's polluting activities; very high levels in some areas appear to be due to natural run-off. There is also evidence that the occurrence of high metal concentrations in one species does not necessarily indicate pollution, since bivalves in general, and oysters in particular, are extremely efficient concentrators of metals from
Poll
Ministry o[ Agriculture, Fisheries and Food, Fisheries laboratory, Remembrance Avenue, Burnham-on-Crouch CMO 8HA, U.K. Hammond, A. L. (1971), Mercury in the environment: natural and human factors, Science, NY, 171 (3973), 788,9. Holden, A. V. and Portmann, J. E. (1970), Monitoring organochlorine residues, Mar. Poll. Bull., 1 (NS) (3), 4t-2, NERC (1971), The seabird wreck in the Irish Sea, Autumn, 1969, Natural Environment ResearCh Council PUblication, Series C, No. 4, 17.
on in Greek
A eo-otmmtlve Greek-American i n v u t i p a o n studies the effect of a sewage outfall on eutrophication in the eastern Mediterranean.
The Nuclear Research Centre "Democritus" is the main research institute in Greece. It has facilities for basic and applied research and for multidisciplinary investigations requiring mainly nuclear facilities. Of the 160 scientific personnel, 70 have postgraduate education. The centre is divided into several divisions and marine pollution studies are being pursued in tim Biology Division by the hydrobiology group, in collaboration with the Department of Oceanography of tM University of Washington, Seattle. The hydrobiology group (six people) is carrying out studies of marine productivity and the effect of pollution in the food chain. A study of marine fouling in oil polluted areas is also carried out by the group (Ignatiades and Becacos-Kontos, 1970). The unpolluted Saronicos Gulf has a low level of productivity and very small amounts of nutrients (BecacosKontos, 1968; Ignatiades and Becacos-Kontos, 1969). In recent years, serious problems of pollution were created by the new sewage outfall at Keratsini (Fig. 1) which introduces the sewage from Athens and its suburbs into the Saronicos Gulf. The Keratsini outfall has visibly affected the primary production in the upper Saronicos Gulf and in February and March, 1970, preliminary investigations of the effect of the Keratsini outfall on the chemistry and biology of the surrounding waters were made jointly with the scientists on the research vessel 158
sea water, and very great differences occur between the levels of accumulation in different, and even closely related, species. The concentration of specific metals may well be exhibited by a particular marine species and it is therefore essential that, when comparisons are made between different areas, the same species should be used. However, because certain species may concentrate specific metals, a general assessment of the metal concentrations in a particular area can only be made if several species from the same area are examined. Finally, the analyses carried out to date suggest that the concentrations of metals in shellfish cannot be used to predict the likely levels in pelagic or demersal fish from the same area. J. E. PORTMANN
Thompson, of the Department of Oceanography, University of Washington. The outfall studies were not a major objective of the Thompson cruise 47, but the cruise was designed to carry out intensive studies of the dynamics of marine biological production in a limited area. For these studies a system of rapid shipboard data acquisition and analysis was developed with further elaboration of the data immediately made possible by computer simulation models being used and developed on board the ship. An IBM 1130 computer with a Calcomp plotter for graphic display, and a Hewlett Packard digitizer and scanning unit to interrogate an array of sensors which measure environmental parameters, constitute the basic Thompson system. Using this system, it is possible to obtain synoptic maps of any parameter which can be measured continuously. The results of a mapping survey made on March 14, 1970 are shown in Figure 2a-d. High concentrations of phosphate, silicate and nitrate (Fig. 2a-c) surround the outfall, with very high gradients prevailing out to a distance of about 2 km. One effect of high nutrients on Mediterranean water is shown in Figure 2d where greatly enhance, d cMorophyll concentrations are shown also to correspond with the outfall. The diffusion of the effluent materials was restricted by light south winds, but nevertheless the effects were visible for a distance of at least 20 kin. To continue this preliminary investigation, a project is being set up in Greece under the International Biological Programme (~BP). The project will be centred in Democritus. The 1BP Integrated Research Programme