- Email: [email protected]
Lead in the marine environment
Book Reviews
1425
Lead in the Marine Environment, edited by MARKO BRANICA and ZDENKA KONRAD, Pergamon Press, 1980, 353 pp., $69.00. T~li concentration and distribution of lead in the marine environment have been the concern of environmental
scientists, social scientists, and politicians for more than a decade. Following the so-called Minamata incident and reports of itai-itai disease in Japan, caused by the consumption of fish contaminated with mercury (Hg) and cadmium (Cd), respectively, it has become clear that serious consequences can follow the contamination of coastal environments by man's activities. Less obvious is the low-level contamination of the open ocean, which has occurred by more disseminated emissions and atmospheric transport of several metals from industrial sources. In order to place such contamination in proper perspective, it is essential to have a first-hand knowledge of the natural cycling mechanisms of each element of concern, the influence that additional anthropogenic supplies have on these cycles, the chemical speciation of the metals in natural waters, and their chronic and sublethal effects on organisms, including man. The problem is complicated in the case of lead because the metal is introduced into the environment mainly in organic form, as various alkyl antiknock compounds, and also probably undergoes methylation, a process which also renders mercury more toxic than it otherwise would be. The volume represents the proceedings of the International Experts' Discussion on Lead Occurrence, Fate and Pollution in the Marine Environment, which was held at Rovinj, Jugoslavia, 18 to 22 October, 1977. Following a brief introduction by the senior editor, 26 chapters deal with a wide variety of topics concerned with the measurement of dissolved and particulate lead in water and biological material, physicochemical studies of the speciation of lead, reports of the concentration of lead in marine waters and organisms, the toxicity of lead to organisms, the analysis of antiknock compounds, and a description and analysis of the effects of the dispersal of a large quantity of tetra-ethyl and tetra-methyl lead in the sea following the sinking of M.V.Cavtat in 1974 offCape Otranto in the southern part of the Adriatic Sea. After a brief chapter by TAYLOR, in which he rightly decries the production of environmental quality data without adequate quality control, PATTERSON and co-workers, in three separate chapters, summarize their extensive data on the levels of lead in marine waters and organisms and, following the recent extensive discussion by the same author (Science, 207, 1167 1176), explicitly state that environmental lead levels are actually much less than one would conclude from the literature and that this is because contamination during sample collection, preparation, and analysis has not been recognized or controlled. For those interested, a listing is given of the analysts capable of "'correctly analyzing" for lead in solution at concentrations ranging from 3 to 150 ng k g t seawater. Two important points are being made by PATTERSON,one being that the open ocean inventory of total lead is very small compared with the industrial input of the metal, the other being that the ability to obtain reliable assays of environmental materials is not necessarily widespread. Three papers are contributed by representatives of one of the largest producers of lead alkyls for use as antiknock additives for gasoline. They bring together useful data on the production, properties, and solution behaviour of these compounds and the methods for their analysis developed by these companies. A rigorous theoretical treatment of the speciation of lead in seawater is presented in the longest chapter by WH1TVn~LI9and TURNr!R. The predominance of PbCO3 species at pH 8 is confirmed and the presence of a mixed ligand complex, Pb(CI, CO3) , is postulated to be important. They also carry out an analysis of the electrochemical availability of lead in seawater using a new theory for plating at the rotating disc electrode, which promises to be useful in view of the growing popularity of electrochemical methods in marine chemistry. Reports of the concentration levels of dissolved and particulate lead in river and coastal waters are provided by FUKAI, MART, and co-workers where we learn that in un-named Mediterranean rivers, lead occurs mainly in particulate form, whereas in coastal Mediterranean waters it is mostly in the dissolved state; moreover, in contaminated coastal waters in Europe the metal is mainly particulate. The association of lead with organic compounds is reported by RASPORand co-workers, and MUSANIand co-workers. Both on theoretical grounds and on the basis of experimental work, it is evident that organic association is not important in the marine environment: complexation sites are occupied mainly by seawater Ca and Mg, in contrast to tYeshwaters, where around 50% of Pb (ll) is apparently completed by dissolved humic substances. It should be noted that the experiments reported used soil humic acids, whereas it is also important to know something about the effects of marine humic substances, which are known to be structurally different. CHAN and WON(; report their identification of the production of tetramethyl lead from lake sediments in laboratory culture and eliminate its formation by inorganic reactions. This compound has not yet been found in the natural environment. Tests of the acute toxicities of alkyl lead compounds on some marine organisms are reported by MADDOCK and TAYLOR, BERITI(" and co-workers determine the hematological effects of the administration of lead acetate to fish, KOSTIAL summarizes his own work on the absorption, retention, and distribution of lead in rats, and FISCrtER reports on the effect of lead salts at the cellular level and confirms that although DNA synthesis is suppressed in the presence of 10 3 to 10- ~M lead, resistance is developed after longterm exposure: this is not apparently due to mutation but more probably because of the production of a factor, probably a protein, in the cell. An important finding is that, in contrast to the effects of Hg and Cd, the inhibitory effects of lead exposure occur at concentrations very much less than the lethal concentrations. A stimulating review of some of the problems with the use of atomic absorption spectrophotometric methods
1426
Book Reviews
for trace metal analysis is given by STOEPPtEt. He complains that there has been a great deal of uncritical use of this technique by untrained analysts and warns that with the advent of new atomization techniques, which yield considerably more sensitivity, even greater analytical errors will be entombed in the literature. Hence, a very large amount of useless data, gathered in pollution studies, which PA'rrmutONclaims is due mainly to the lack of control of contamination, has also been generated by the rash use of the atomic absorption spectrophotometer. That this is a real problem is nicely illustrated by the account of the Cavtat incident by H^RIUSON, who also attempts to review the follow-up monitoring work. The data on the levels and the distribution of total and organo-lead compounds in the vicinity of the wreck are so widely scattered, and the supposed background levels are so very high, that I conclude that we know very little about this useful experiment. In a concluding chapter, limtm-L~J) gives a rather satisfied appraisal, using simple arithmetical estimates of consumption and probable lead levels in food from marine sources, of the probable importance of lead in the human diet and concludes that inorganic lead appears to be of minor importance as a pollutant in the ocean. The approach used here is somewhat similar to that used for identifying the levels of exposure to artificial radionuclides by so-called critical groups, which produces only an initial appraisal of the extent of the problem. Considerably more work on the very long-term effects of ionizing radiation is now being carried out, and it would seem prudent to follow the same approach with beavy-metai contamination. On balance, this is a very useful summary volume on lead in the marine environment, which brings a great deal of disparate data and usefully poses some important questions. It gives a glimpse of the work that is now going on, and the advances that are being made. in this difficult branch of marine pollution chemistry. S. E. Carver1
Department oj Oceanography The University of British Columbia Vancouver, B.C. V6T IW5 Canada
1425
Lead in the Marine Environment, edited by MARKO BRANICA and ZDENKA KONRAD, Pergamon Press, 1980, 353 pp., $69.00. T~li concentration and distribution of lead in the marine environment have been the concern of environmental
scientists, social scientists, and politicians for more than a decade. Following the so-called Minamata incident and reports of itai-itai disease in Japan, caused by the consumption of fish contaminated with mercury (Hg) and cadmium (Cd), respectively, it has become clear that serious consequences can follow the contamination of coastal environments by man's activities. Less obvious is the low-level contamination of the open ocean, which has occurred by more disseminated emissions and atmospheric transport of several metals from industrial sources. In order to place such contamination in proper perspective, it is essential to have a first-hand knowledge of the natural cycling mechanisms of each element of concern, the influence that additional anthropogenic supplies have on these cycles, the chemical speciation of the metals in natural waters, and their chronic and sublethal effects on organisms, including man. The problem is complicated in the case of lead because the metal is introduced into the environment mainly in organic form, as various alkyl antiknock compounds, and also probably undergoes methylation, a process which also renders mercury more toxic than it otherwise would be. The volume represents the proceedings of the International Experts' Discussion on Lead Occurrence, Fate and Pollution in the Marine Environment, which was held at Rovinj, Jugoslavia, 18 to 22 October, 1977. Following a brief introduction by the senior editor, 26 chapters deal with a wide variety of topics concerned with the measurement of dissolved and particulate lead in water and biological material, physicochemical studies of the speciation of lead, reports of the concentration of lead in marine waters and organisms, the toxicity of lead to organisms, the analysis of antiknock compounds, and a description and analysis of the effects of the dispersal of a large quantity of tetra-ethyl and tetra-methyl lead in the sea following the sinking of M.V.Cavtat in 1974 offCape Otranto in the southern part of the Adriatic Sea. After a brief chapter by TAYLOR, in which he rightly decries the production of environmental quality data without adequate quality control, PATTERSON and co-workers, in three separate chapters, summarize their extensive data on the levels of lead in marine waters and organisms and, following the recent extensive discussion by the same author (Science, 207, 1167 1176), explicitly state that environmental lead levels are actually much less than one would conclude from the literature and that this is because contamination during sample collection, preparation, and analysis has not been recognized or controlled. For those interested, a listing is given of the analysts capable of "'correctly analyzing" for lead in solution at concentrations ranging from 3 to 150 ng k g t seawater. Two important points are being made by PATTERSON,one being that the open ocean inventory of total lead is very small compared with the industrial input of the metal, the other being that the ability to obtain reliable assays of environmental materials is not necessarily widespread. Three papers are contributed by representatives of one of the largest producers of lead alkyls for use as antiknock additives for gasoline. They bring together useful data on the production, properties, and solution behaviour of these compounds and the methods for their analysis developed by these companies. A rigorous theoretical treatment of the speciation of lead in seawater is presented in the longest chapter by WH1TVn~LI9and TURNr!R. The predominance of PbCO3 species at pH 8 is confirmed and the presence of a mixed ligand complex, Pb(CI, CO3) , is postulated to be important. They also carry out an analysis of the electrochemical availability of lead in seawater using a new theory for plating at the rotating disc electrode, which promises to be useful in view of the growing popularity of electrochemical methods in marine chemistry. Reports of the concentration levels of dissolved and particulate lead in river and coastal waters are provided by FUKAI, MART, and co-workers where we learn that in un-named Mediterranean rivers, lead occurs mainly in particulate form, whereas in coastal Mediterranean waters it is mostly in the dissolved state; moreover, in contaminated coastal waters in Europe the metal is mainly particulate. The association of lead with organic compounds is reported by RASPORand co-workers, and MUSANIand co-workers. Both on theoretical grounds and on the basis of experimental work, it is evident that organic association is not important in the marine environment: complexation sites are occupied mainly by seawater Ca and Mg, in contrast to tYeshwaters, where around 50% of Pb (ll) is apparently completed by dissolved humic substances. It should be noted that the experiments reported used soil humic acids, whereas it is also important to know something about the effects of marine humic substances, which are known to be structurally different. CHAN and WON(; report their identification of the production of tetramethyl lead from lake sediments in laboratory culture and eliminate its formation by inorganic reactions. This compound has not yet been found in the natural environment. Tests of the acute toxicities of alkyl lead compounds on some marine organisms are reported by MADDOCK and TAYLOR, BERITI(" and co-workers determine the hematological effects of the administration of lead acetate to fish, KOSTIAL summarizes his own work on the absorption, retention, and distribution of lead in rats, and FISCrtER reports on the effect of lead salts at the cellular level and confirms that although DNA synthesis is suppressed in the presence of 10 3 to 10- ~M lead, resistance is developed after longterm exposure: this is not apparently due to mutation but more probably because of the production of a factor, probably a protein, in the cell. An important finding is that, in contrast to the effects of Hg and Cd, the inhibitory effects of lead exposure occur at concentrations very much less than the lethal concentrations. A stimulating review of some of the problems with the use of atomic absorption spectrophotometric methods
1426
Book Reviews
for trace metal analysis is given by STOEPPtEt. He complains that there has been a great deal of uncritical use of this technique by untrained analysts and warns that with the advent of new atomization techniques, which yield considerably more sensitivity, even greater analytical errors will be entombed in the literature. Hence, a very large amount of useless data, gathered in pollution studies, which PA'rrmutONclaims is due mainly to the lack of control of contamination, has also been generated by the rash use of the atomic absorption spectrophotometer. That this is a real problem is nicely illustrated by the account of the Cavtat incident by H^RIUSON, who also attempts to review the follow-up monitoring work. The data on the levels and the distribution of total and organo-lead compounds in the vicinity of the wreck are so widely scattered, and the supposed background levels are so very high, that I conclude that we know very little about this useful experiment. In a concluding chapter, limtm-L~J) gives a rather satisfied appraisal, using simple arithmetical estimates of consumption and probable lead levels in food from marine sources, of the probable importance of lead in the human diet and concludes that inorganic lead appears to be of minor importance as a pollutant in the ocean. The approach used here is somewhat similar to that used for identifying the levels of exposure to artificial radionuclides by so-called critical groups, which produces only an initial appraisal of the extent of the problem. Considerably more work on the very long-term effects of ionizing radiation is now being carried out, and it would seem prudent to follow the same approach with beavy-metai contamination. On balance, this is a very useful summary volume on lead in the marine environment, which brings a great deal of disparate data and usefully poses some important questions. It gives a glimpse of the work that is now going on, and the advances that are being made. in this difficult branch of marine pollution chemistry. S. E. Carver1
Department oj Oceanography The University of British Columbia Vancouver, B.C. V6T IW5 Canada