Reviews.
E. F. Armstrong and L. M. Miall. "Raw Materials from the Sea." pp. XI
and 164: 21 plates. Constructive Publications Limited, Leicester, 1943.
This is primarily a book for the general reader interested in the methods
and economic possibilities of extracting materials from lakes and the sea. A
good account is given of the history, economics, and modes of extraction of
common salt, bromine, and magnesium from sea water. The modern techniques are clearly described and in more detail than has hitherto appeared
in the general literature. The account of the D o w process for the extraction
of magnesium is particularly good.
In the chapter on potassium the activities of Palestine Potash Ltd. are fully
described, and some attention is given to the American work. A chapter on
products from sea-weed is devoted particularly to the extraction of iodine, little
attention being given to the organic materials now being manufactured in
considerable quantities. A discussion of the production of potable water from
salt water is included. References are given to the more important of the
modern publications on commercial processes and their economics.
Preceding these chapters on industrial work are three dealing with the
physics, chemistry, geochemistry, and biology of the ocean. In such a small
space the treatment is necessarily very superficial and indeed a number of
erroneous statements are found in this section.
H.B.
N. W. Rakestraw and T. von Brand. "Decomposition and regeneration
of nitrogenous organic matter in sea water." ' Biol. Bull. 72, No. 2, pp.
165—175. Cambridge & Woods Hole, Mass., 1937.
T. von Brand, N. W. Rakestraw and C. E. Renn. "Further experiments
on the decomposition and regeneration of nitrogenous organic matter
in sea water." Biol. Bull. 77, No. 2, pp. 285—296. Cambridge &
Woods Hole, Mass., 1939.
T. von Brand and N. W. Rakestraw. "Decomposition and regeneration
of nitrogenous organic matter in sea water. 111. Influence of temperature and source and condition of water." Biol. Bull. 79, No. 2, pp.
231—236. Cambridge & Woods Hole, Mass., 1940.
114
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T. von Brand and N. W. Rakestraw. "Decomposition and regeneration
of nitrogenous organic matter in sea water. IV. Inter-relationship
of various stages; influence of concentration and nature of paniculate
matter." Biol. Bull. 81, No. 1, pp. 63—69. Cambridge & Woods
Hole, Mass., 1941.
T. von Brand, N. W. Rakestraw and J. W. Zabor. "Decomposition and
regeneration of nitrogenous organic matter in sea water. V. Factors
influencing the length of the cycle; observations upon the gaseous and
dissolved organic nitrogen." Biol. Bull. 83, No. 2, pp. 273—282.
Cambridge & Woods Hole, Mass., 1942.
N. W. Rakestraw and T. von Brand. "Decomposition and regeneration
of nitrogenous organic matter in sea water. VI. The effect of enzyme
poisons." Biol. Bull. 92, No. 2, pp. 110—114. Cambridge & Woods
Hole, Mass., 1947.
This series of papers constitutes an important contribution to our knowledge
of the mode of decomposition of plankton material under experimental conditions. Since the fertility of the sea is dependent upon the cycle by which
inorganic nitrogenous compounds are regenerated, the results are of widespread importance.
The experimental procedure was similar throughout the work and, in
general, consisted in allowing various kinds of planktonic and other material
to decompose in carboys of sea water kept in the dark; samples of the cultures were withdrawn at intervals and by analysis, the changes in the ammoniacal, nitrite, and nitrate nitrogen fractions have been followed during
decomposition processes. The variables whose action has been considered are
clearly indicated by the titles of the individual papers given above.
Throughout the series a similar decomposition sequence was observed,
namely, particulate matter gave rise to ammonia which was oxidized to
nitrite, the latter being in turn oxidized to nitrate. Although the length of
any stage varied from one series of experiments to another (the total duration
of the nitrite stage being particularly irregular) the sequence of events was
always similar. The rate of decomposition was greatest in the first few days,
with the production' of ammonia; ultimately the rate of formation of ammonia slowed down and eventually ceased. During this period neither nitrite
nor nitrate were formed. Although not conclusively demonstrated, the chemical evidence suggests that soluble organic nitrogenous compounds do not play
an important part as precursors of ammonia. However, when a second cycle
was carried out in the same culture, by further addition of decomposable
material, there was a lag in the appearance of ammonia in comparison with
the disappearance Oi particulate nitrogen, suggesting that under these circumstances the formation of intermediate nitrogenous compounds of high molecular weight may take place.
Concurrently with the production of ammonia there was a rapid development of the bacterial flora, and it is therefore suggested that autolytic
decomposition plays a comparatively small part. It should be noted, however, that the absolute numbers of bacteria were never high; indeed, little
larger numbers were obtained than are present in stored, unfiltered sea water
without added material. Nitrate appeared only when nitrite disappeared,
which never seemed to happen as long as a significant quantity of ammonia
remained. Under anaerobic conditions a little ammonia may be formed, but
a strong odour of hydrogen sulphide was observed and no nitrite appeared.
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115
The behaviour of ammonia, nitrite, and nitrate in these experiments is
similar to that obtained by other workers using pure bacterial cultures and
the appropriate substrate. The slowest of these three stages is the oxidation
of nitrite to nitrate, an efficient population of the specialized Nitrobacter
flora apparently developing at a slower rate. When decomposition had
stopped there was 20—35 % residual nitrogen (calculated on organic plankton basis) and this was presumably present either as non-decomposable residues,
bacterial cells, or other forms.
The concentration of particulate matter had little effect on the rate of
the processes, but the source of material had some effect. The rate of decomposition was most rapid with mixed plankton, slower with pure diatoms
(from cultures) and slowest with yeast cells. A ciliate behaved similarly in
harbour water to the diatoms but did not proceed to nitrate in deep sea water.
The course which the decomposition takes when new organic matter is
added depends on the bacterial flora which then predominates. There was
no evidence of the inhibition of the formation of nitrite or nitrate by ammonia and in general a shortening of the cycle takes place, so that, for example,
ammonia and nitrite appear only in small quantities if new organic matter
is added after the development of a vigorous nitrate flora. Low temperature
may completely inhibit part of the processes; nitrite formation may be completely inhibited or only retarded depending upon the particular organisms
present, whilst oxidation of nitrite to nitrate was less inhibited than the
nitrite-ammonia conversion.
This nitrogen cycle can be repeated; exposure to light at the nitrate
stage and inoculation with living diatoms resulted in a rapid growth of the
latter with a consequent depletion of the nitrate. Three successive cycles were
in this way carried through and since each addition of new organic matter
resulted in an undecomposable residue, the total level of refractory residual
nitrogen gradually rose with each successive cycle. Further, inoculation and
exposure to light either at the ammonia maximum or prior to the nitrate
stage lead both to a depletion of the inorganic nitrogen present and to a
vigorous growth of diatoms, indicating that at these stages no toxic compounds had been formed which would inhibit the development of phytoplankton.
The source of the water had an important influence on the decomposition.
The behaviour with water from the oxygen minimum layer (800 metres) and
from the surface of a deep sea station was similar to that of the inshore water
already described, but with deep water (1200 metres) from this station
decomposition did not proceed further than the formation of ammonia.
Further, none of the samples showed any difference between sterilized (by
filtration) and untreated sub-samples, suggesting that the necessary bacterial
inoculum was carried by the diatoms. It therefore follows either that the
deep water contains a factor inhibiting the production of an oxidizing
bacterial flora, or that it lacks an essential factor necessary for its development. That it was lack of an essential constituent, rather than the presence
of an inhibiting factor, is indicated by the fact that evaporation and ignition
of harbour water prior to addition of particulate matter resulted in a retardation in the formation of ammonia, whilst production of nitrite was even
more retarded and there was a complete absence of nitrate formation. However, boiled diatoms showed little difference from living material when
introduced into either untreated or sterilized sea water, and the maintenance
of aseptic conditions is called into question by the authors. The evidence
] 16
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suggests that it is easier to eliminate the organisms responsible for oxidation
than those for ammonia formation. However, on one occasion the decomposition of diatoms proceeded normally, nitrate being ultimately produced
in deep water cultures.
In their most recent paper (Part VI) in taking up these studies again,
the effect of a number of enzyme poisons on various stages of the cycle have
been investigated. The production of ammonia by micro-organisms may take
place by hydrolytic, reductive, and oxidative deamination depending both
on the conditions and on the micro-organisms present. That KCN retards
the production of ammonia in these decomposition cultures, but does not
completely suppress it, suggests that oxidative deamination (known to be
completely inhibited by KCN in all examples studied) is the most important
route to the liberation of ammonia; that some ammonia production still takes
place, even in the presence of cyanide may be due either to a weakly developed mechanism by the same bacteria, or to the slow production of a different
bacterial flora liberating ammonia by an alternative method. Nitrifiers are
more sensitive and were destroyed by the usual well-known poisons used.
Cyanides, carbamates, iodates, and fluorides interfere with nitrite and nitrate
formation, suggesting that dehydrogenases are involved in their formation.
The possible uses of KCN as a preservative for samples prior to analysis for
nitrite and nitrate are clearly indicated.
Several of these decomposition cultures showed an unexplained increase
in the total nitrogen during the experiments, i.e., more was generated in the
soluble form than disappeared from the planktonic material. Four possible
causes were examined:—
1. Participation of other forms of nitrogen, particularly dissolved organic
nitrogen.
2. Sampling errors.
3. Nitrogen fixation.
4. Contamination.
The tracing of this increase is a matter of very considerable technical
difficulty, but the evidence obtained was largely in favour of contamination
from air during the experimental period.
These authors have covered the influence of a large number of variables,
each of which raises its own particular new problems. An intensive study
of the mechanism by which any of these affects the processes concerned is
now required, when it should be possible to relate more closely the results of
these and other culture experiments to the changes taking place in the sea.
H. Barnes.
K. F. Wiborg.
"The Production of Zooplankton in the Oslo Fjord in
1933—1934, with special reference to the Copepods." Hvalradets
Skr., No. 21, pp. 87, 5 figs. Oslo, 1940.
The collections on which this intensive study of the zooplankton of the
Oslo fjord was based were made in conjunction with hydrographic and
phytoplankton investigations from June 1933 to May 1934. A few supplemental hauls were made in 1938. The material was collected by vertical
hauls, most of them in two steps, from the bottom, thus ensuring that the
whole depth was sampled. Of these collections the copepoda formed the