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Organic matter in seawater
trends in analytical chemistry, vol. 1, no. 6,1982 .
Organic matter in seawater Marine Organic Chemistry: Evolution, Composition, Znteractions and Chemistry of Organic Matter in Seawater, Elsevier Oceanography Series, 31, edited by E. K. Duursma and R. Dawson, Elsevier Scientific Publishing Co., 1981, $lOS.OOlDfl 215.00 (xiv + 521 pages) ZSBN 0 444 41892 X
This is the first English-language book devoted to the chemistry of organic matter in seawater. It consists of chapters written by an international group of experts under the general editorship of Egbert Duursma and Rodger Dawson, who also provide introductory and concluding chapters. Of particular interest to analytical chemists are the descriptions and discussions of techniques in a few of the contributions, and it is upon these that I will concentrate my comments. Most of the interesting chemistry in the oceans takes place at interfaces. Away from the coast, the air-sea and ocean-sediment interfaces are separated on average by 4000 m of water. Within this, surfaces for chemical reaction are provided by inanimate particulate matter which is predominantly of organic origin. Although the definition of this fraction is operational - it depends upon the porosity of the filter employed - it is not, as Cauwet (Chapter 4) states ‘purely arbitrary’. In fact, it approximates the lower limit
for detailed examination under the light microscope and the upper limit of particles which exhibit Brownian motion. Earlier studies of this fraction are confused by differences in sampling techniques and analytical methods, and the primary recommendation of this review is that effort should be directed to the standardization of recovery techniques and intercalibration of existing analytical methods. These, for the measurement of the ‘bulk properties’ of dissolved (DOC), particulate (POC), and volatile (VOC) organic carbon fractions, are described in the chapter by MacKinnon, himself a major contributor to recent advances in analytical technique. He, rightly, does not recommend the use of the oxidizability parameter (widely used in the analysis of fresh and wastewaters of high organic load), for unpolluted marine samples; he also prefers gravity over vacuum filtration and silver over glass-fibre filters; these are essential to improve the quality of quantitative POC measurement in seawater. His own preference for dry combustion as the method for the analysis of DOC is tempered by the recognition that photo-oxidation of the liquid phase, though incomplete when the sample contains particles, has advantages in routine application, since it can be easily automated. Analytical methods for the characterization of different classes of organic compounds in seawater are dealt with by Dawson and Liebezeit, themselves
innovators in this field. They confine themselves to methods of analysis of naturally-occurring organic compounds, which are often ignored in the more extensive literature dealing with the analysis of man-made additions to the marine environment. Detailed descriptions and critiques of methods for amino acids, carbohydrates, fatty acids and other hydrophobic compounds in seawater make this one of the most interesting chapters in the book. Compounds with biological activity are treated in less detail, but the tabulation of methods for the determination of enzyme activity in marine samples is helpful. There are other chapters of interest chemists. That of to analytical Skopintsev on the so-called ‘humic’ material dissolved in seawater reviews the classical work of the last half century and the review by Saliot, of natural hydrocarbons in seawater, gives sufficient details of methods of sampling and analysis without making the chapter unreadable. A section on sources of natural hydrocarbons and processes controlling their distribution is particularly useful as the natural background upon which anthropogenie inputs are imposed is too often ignored in environmental studies and statements. Modern methods ofword processing should surely have allowed for a more complete subject index, e.g. although three references to ‘lignin’ are given, the word occurs with a greater frequency in the text. References should have been collected together and not printed at the end of each individual chapter. We performed this task in my laboratory: it took 30 man-hours, and considerably reduced the bulk of the citations by eliminating duplication. This could, perhaps, have reduced the daunting cost of the book. Despite these reservations, this is a valuable compilation which belongs in the libraries of all those who study the organic matter of seawater, and those who instruct others now have a text to which they may confidently refer their students. R. POCKLINGTON
Dr Roger Pocklington is at the Atlantic Oceanographic Laboratory Bedford Institute of Oceanography, P.O. Box I&XT, Dartmouth, N.S., Canada B2Y 4A2.
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Organic matter in seawater Marine Organic Chemistry: Evolution, Composition, Znteractions and Chemistry of Organic Matter in Seawater, Elsevier Oceanography Series, 31, edited by E. K. Duursma and R. Dawson, Elsevier Scientific Publishing Co., 1981, $lOS.OOlDfl 215.00 (xiv + 521 pages) ZSBN 0 444 41892 X
This is the first English-language book devoted to the chemistry of organic matter in seawater. It consists of chapters written by an international group of experts under the general editorship of Egbert Duursma and Rodger Dawson, who also provide introductory and concluding chapters. Of particular interest to analytical chemists are the descriptions and discussions of techniques in a few of the contributions, and it is upon these that I will concentrate my comments. Most of the interesting chemistry in the oceans takes place at interfaces. Away from the coast, the air-sea and ocean-sediment interfaces are separated on average by 4000 m of water. Within this, surfaces for chemical reaction are provided by inanimate particulate matter which is predominantly of organic origin. Although the definition of this fraction is operational - it depends upon the porosity of the filter employed - it is not, as Cauwet (Chapter 4) states ‘purely arbitrary’. In fact, it approximates the lower limit
for detailed examination under the light microscope and the upper limit of particles which exhibit Brownian motion. Earlier studies of this fraction are confused by differences in sampling techniques and analytical methods, and the primary recommendation of this review is that effort should be directed to the standardization of recovery techniques and intercalibration of existing analytical methods. These, for the measurement of the ‘bulk properties’ of dissolved (DOC), particulate (POC), and volatile (VOC) organic carbon fractions, are described in the chapter by MacKinnon, himself a major contributor to recent advances in analytical technique. He, rightly, does not recommend the use of the oxidizability parameter (widely used in the analysis of fresh and wastewaters of high organic load), for unpolluted marine samples; he also prefers gravity over vacuum filtration and silver over glass-fibre filters; these are essential to improve the quality of quantitative POC measurement in seawater. His own preference for dry combustion as the method for the analysis of DOC is tempered by the recognition that photo-oxidation of the liquid phase, though incomplete when the sample contains particles, has advantages in routine application, since it can be easily automated. Analytical methods for the characterization of different classes of organic compounds in seawater are dealt with by Dawson and Liebezeit, themselves
innovators in this field. They confine themselves to methods of analysis of naturally-occurring organic compounds, which are often ignored in the more extensive literature dealing with the analysis of man-made additions to the marine environment. Detailed descriptions and critiques of methods for amino acids, carbohydrates, fatty acids and other hydrophobic compounds in seawater make this one of the most interesting chapters in the book. Compounds with biological activity are treated in less detail, but the tabulation of methods for the determination of enzyme activity in marine samples is helpful. There are other chapters of interest chemists. That of to analytical Skopintsev on the so-called ‘humic’ material dissolved in seawater reviews the classical work of the last half century and the review by Saliot, of natural hydrocarbons in seawater, gives sufficient details of methods of sampling and analysis without making the chapter unreadable. A section on sources of natural hydrocarbons and processes controlling their distribution is particularly useful as the natural background upon which anthropogenie inputs are imposed is too often ignored in environmental studies and statements. Modern methods ofword processing should surely have allowed for a more complete subject index, e.g. although three references to ‘lignin’ are given, the word occurs with a greater frequency in the text. References should have been collected together and not printed at the end of each individual chapter. We performed this task in my laboratory: it took 30 man-hours, and considerably reduced the bulk of the citations by eliminating duplication. This could, perhaps, have reduced the daunting cost of the book. Despite these reservations, this is a valuable compilation which belongs in the libraries of all those who study the organic matter of seawater, and those who instruct others now have a text to which they may confidently refer their students. R. POCKLINGTON
Dr Roger Pocklington is at the Atlantic Oceanographic Laboratory Bedford Institute of Oceanography, P.O. Box I&XT, Dartmouth, N.S., Canada B2Y 4A2.
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