ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER AND THEIR RELATION TO THE COMPOSITION OF PLANKTON This is the text from Alfred Charles Redfield paper

Abstract

Following, you will find the manuscript by Alfred Redfield printed in 1933. This paper is probably one of the most important papers in the history of earth sciences and such is frequently read by scholars and students. As far as I could find it is only available in the form of a scanned PDF which is not usefull for many applications. I tried to remain as close to the original paper as possible but inevitably might have made some mistakes. This is distributed with the intention of making the original paper more accessible and without taking any credit. Enjoy reading Yair suari To cite this paper: Redfield, Alfred Clarence. "On the proportions of organic derivatives in sea water and their relation to the composition of plankton." James Johnstone memorial volume (1934): 176-192.

Full text

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
1
Following, you will find the manuscript by Alfred Redfield printed in
1933. This paper is probably one of the most important papers in the
history of earth sciences and such is frequently read by scholars and
students. As far as I could find it is only available in the form of a
scanned PDF which is not usefull for many applications. I tried to
remain as close to the original paper as possible but inevitably might
have made some mistakes.
This is distributed with the intention of making the original paper more
accessible and without taking any credit.
Enjoy reading
Yair suari
To cite this paper:
Redfield, Alfred Clarence. "On the proportions of organic derivatives in sea water and their relation to the
composition of plankton." James Johnstone memorial volume (1934): 176-192.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
2
ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER AND
THEIR RELATION TO THE COMPOSITION OF PLANKTON
ALFRED C. REDFIELD
PROFESSOR OF PHYSIOLOGY, HARVARD UNIVERSITY, AND. SENIOR BIOLOGIST, WOODS HOLE OCEANOGRAPHIC INSTITUTION
(Received, September 5, 1933)
abstract
“ Chemical analysis shows that the animal and plant body is mainly built up from the four elements,
nitrogen, carbon, hydrogen, and oxygen. Added to these are the metals, sodium, potassium and iron,
and the non-metals, chlorine, sulphur and phosphorus. Calcium or silicon are also invariably present as
the bases of calcareous or siliceous skeletons. All these, with some others, are indispensable
constituents of the organic body, and in an exhaustive study of the cycle of matter a from the living to
the non-living phases, and vice versa, we should have to trace the course of each. " James Johnstone,
"Conditions of Life in the Sea,” p. 273. 1908.
It is now well recognized that the growth of plankton in the surface layers of the sea is limited in
part by the quantities of phosphate and nitrate available for their use and that the changes in the
relative quantities of certain substances in sea water are determined in their relative proportions by
biological activity. When it is considered that the synthetic processes leading to the development of
organic matter are Limited to the surface layers of the sea in which photosynthesis can take place, it
becomes evident that the chemical changes which occur in the water below this zone must arise chiefly
from the disintegration of organic matter In so far as this disintegration goes to completion, the changes
in the derived inorganic constituents of sea water must depend strictly upon the quantity and
composition of the organic matter which is being decomposed. This is true quite irrespective of the
agencies of decomposition, be they bacterial action, the autolytic enzymes of the original tissues
themselves, or the metabolic processes of deep sea animals which utilize the organic matter as food.
Thus, in the decomposition of a given quantity of organic matter, the quantity of oxygen consumed must
be determined by the quantity of carbon, nitrogen, hydrogen, Sulphur, and phosphorus to be oxidized,
and the relative changes in the quantity of oxygen, nitrate, phosphate, carbonate, and sulfate must
depend exactly on the elementary composition of the plankton.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
3
It has seemed possible that the chemical composition of the population of the seas may be
sufficiently uniform, and the contributions of the substances in question from other sources sufficiently
limited, to permit the discovery of telations between their concentration in sea water which would be
serviceable in the study of oceanic problems.
An examination of the data on nitrate and phosphate in the water of various seas secured by the
"Dana" in the course of the Carlsberg Foundation’s oceanographical expeditions around the world in
1928-1929 proved encouraging from this point of view. Thanks to the collaboration of Dr. Norris
Rakestraw a more complete set of data, showing the relative concentrations of oxygen, nitrate,
phosphate, and carbonate at different depths, was obtained from a number of Stations made by the
"Atlantis" in the deep waters of the western Atlantic Ocean. Six stations were occupied in the Sargasso
Sea between Bermuda and the southern coast of the United States. In this region water samples were
obtained at successive depths from at least three distinct water masses: (1) the surface water in
intimate relation with the atmosphere and in which photosynthetic activity has reduced the nutrient
substances to a minimum; (2) the layer of intermediate depth—most clearly marked at 700 meters and
characterized by minimal oxygen concentrations and high concentrations in organic derivatives; and (3),
the deep water of polar origin of relatively uniform composition below 1, 500 meters, which has also
been the seat of organic decomposition. Between these layers lie zones in which the water has
intermediate characters due to the mixing of the primary water masses.
The
characteristics of the water at the various stations occupied are unusually uniform both as regards
temperature and salinity and the concentrations of the biologically significant substances. A seventh

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
4
station was occupied in the western edge of the Gulf Stream outside the Gulf of Maine. Here the layer
characterized by minimal oxygen concentration is nearer the surface and the deep cold water lies within
500 meters of the surface. The numbers and positions of the stations are given in Table 1. The station
data will be published in the Bulletin Hydrographique of the International Council for the Exploration of
the Sea.
From the data for oxygen content and temperature, the amount of oxygen which has
disappeared from the water since its exposure to the atmosphere has been estimated, assuming that
the water was saturated at that time and had the temperature which characterized it in situ. While
neither of these assumptions are probably strictly correct, they Provide the only definite method
available to arrive at the amount of oxygen utilized at the various depths. From the data for pH as
measured at the temperature of the ship's laboratory the total carbonate content, ΣCO2 of the water
samples was estimated with the aid of the tables provided by Buch, Harvey, Wattenberg, and
Gripenberg (19 32) These, together with the direct analyses of nitrate and phosphate, give a measure of
the principal products formed by the complete oxidation of the carbon, nitrogen, and phosphorus of the
biological population, together with the amount of dissolved oxygen which has disappeared in the
process.
The data obtained for the water masses underlying the various stations are plotted in Figs. 1, 2
and 3. In these diagrams the concentration of nitrate characterizing each water sample is plotted against
one of the other constituents in order to show whether the concentrations of these constituents vary in
a correlated fashion. The concentrations are expressed in milligram atoms or in millimols per liter, as
suggested by. Cooper (1933), since this notation yields values proportional to the number of atoms of
nitrogen, carbon, and phosphorus present in the constituents in question.
To consider first the relation between nitrate and phosphate concentration in the water
samples, shown in Fig. 1, it is apparent that a very close correlation exists. Any gain or loss in nitrate
content observed in comparing one water sample with another is accompanied by a strictly proportional
gain or loss in phosphate content. The water samples in which the concentrations were low were from
near the surface the quantities of nitrate and phosphate increase with increasing depth. The straight
line drawn through the points describing the nitrate-phosphate correlation has the slope demanded if,
for every three grams of nitrogen added to or subtracted from the water, one gram of PO, (or 2 gram of
P2O5 also made its appearance or disappearance. This corresponds to a ratio of 20 atoms of nitrogen to
1 atom of phosphorus.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
5
Correlation between concentrations of nitrate and phosphate in the waters of
western Atlantic Ocean. Ordinate, concentration of nitrate, units 10-3 millimols per
liter; abscissa, concentration of phosphate, units 10-3 millimols per liter. The line
represents a ratio of ΔN : ΔP = 20:1 milligram atoms.
On the assumption that these changes are due solely to the decomposition or synthesis of
organic matter, these ratios may be taken to reflect the proportions of nitrogen and phosphorus in the
plankton community taken as a whole.
The correlation between the gain in concentration of nitrate and the loss in concentration of
oxygen, as shown in Fig. 2, is almost equally good for the water samples collected from depths less than
1,000 meters in the Sargasso Sea, and 40oo meters in the Gulf Stream, depths which mark the transition
between the intermediate layer of low oxygen content and the deeper layer of cold water. The data for

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
6
greater depths, indicated by open circles in the figure, depart strongly from the expected correlation an
anomaly to which we will return. Above these depths, however, the variation of nitrate concentration
and oxygen utilization is in the proportion of 1 millimol of nitrate to 6 millimols of oxygen.
The correlation between the concentrations of nitrate and carbonate shown in Fig. 3 is less
precise owing to the greater variation in the carbonate measurements. This is due to the fact that the
total variation in carbonate content is
Correlation between concentration of nitrate and amount of oxygen utilized
in waters of western Atlantic Ocean. Ordinate, concentration of nitrate, units 10-3
millimols per liter. The line represents a ratio of oxygen used: ΔN = 6: 1. Points
representing stations from a depth below 400 meters in the Gulf Stream and below
1,000 meters in the Sargasso Sea are represented by open circles.
only a small part of the amount present, to the indirect nature of the method of estimating
carbonate, to possible variations in buffer capacity which have been neglected in these estimations, and

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
7
to exchange in CO2 between air and the surface waters. Nevertheless, taking the data as a whole,
carbonate content is correlated with nitrate content. The envelopes drawn about the points in Fig. 3
have a slope corresponding to a ratio of 1 millimol of nitrate to 7 of carbonate. The value of this ratio is
not as securely established as that relating nitrate to phosphate and to oxygen utilization.
Correlation between concentration of nitrate and total carbonate in waters
of, western Atlantic Ocean. Ordinate, concentration of nitrate, units 10-3 millimols
per liter; abscissa, concentration of carbonate, units 10-3 millimols per liter. The slope
of the envelopes corresponds to a ratio of ΔC: ΔN= 7:1 milligram atoms.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
8
If we take the ratio of change in nitrate to carbonate to be 7: 1 and that of nitrate to oxygen
utilization to be 6 : 1, it follows that the ratio of carbonate to oxygen is 7: 6 or 1.17: 1 This ratio is close
to that characterizing photosynthetic processes and the decomposition of the principal classes of
organic compounds. Its variation from the theoretical is not greater than the uncertainty of the
carbonate measurements.
It appears from the foregoing data that, with the exception of the anomaly quoted in connection
with the oxygen content of the deep water, the concentrations of nitrate, phosphate, and carbonate in
samples of oceanic sea water of widely different origin vary in such a way as might be expected if the
different samples contained the products of the complete disintegration and oxidation of organic
material of similar composition, and that they differ only in the quantity of such material which has
arrived at and remains in this degree of decomposition. Furthermore, the loss in oxygen agrees
approximately with that to be expected from the quantity of carbonate gained. The proportions of
carbon, nitrogen and phosphorus present in the organic material from which the carbonate, nitrate, and
phosphate may be supposed to be derived are approximately 140 : 20: 1 atoms or 100:16.7:1.85 grams
1
.
It is pertinent to inquire how these proportions agree with those actually found in various
members of the plankton community. Naturally each kind of organism is found to have a characteristic
composition different from that of other kinds, and unfortunately no adequate means of obtaining a
truly representative sample of the entire population is available. However; by considering the
composition of the plankton yielded by various kinds of haul, some idea may be obtained as to the
validity of the foregoing considerations.
1
This comparison presupposes that nitrate nitrogen may be regarded as the sole source of nitrogen
available to the plankton. Strictly speaking, this is not the case. Of other sources of nitrogen, nitrite is
known to occur in oceanic waters in concentrations too small to be significant in computations of this
sort. Professor Krogh has recently made observations on the nitrogen present as ammonia and as
organic compounds in the deeper waters of the western Atlantic. His results indicate that ammonia is
present in only small quantities. Organic compounds in the sea water contain relatively large amounts of
nitrogen, but as the concentration of these does not vary greatly from surface to bottom, this source of
nitrogen does not appear to be readily available for conversion into living matter.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
9
A number of elementary analyses of various kinds of plankton are recorded in Table I. They
show that the proportions of carbon, nitrogen, and phosphorus as calculated from the carbonate,
nitrate, and phosphate composition of the sea are not greatly different from those observed in various
plankton, and on the whole the latter differ among themselves much more than their average differs
from the calculated ratios.
In this connection it is of interest to note that Braarud and Fgyn (1930) have observed that each
cell of Chlamydomonas removes 2.98 x 10-12 gr. NO3 nitrogen and o.98 x10-4 gr. PO5 from the sea water
in which it grows. Here we see in a laboratory experiment an organism modifying the concentration of
nitrate and phosphate in the medium in a ratio (ΔN : ΔP = 15: 1) not very different from that observed in
the oceans as a whole.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
10

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
11
Fig 4. Correlation between concentration of nitrate and phosphate in waters of the Atlantic, Indian and Pacific Oceans, Data
of Thompson. Ordinate concentration of nitrate nitrogen, units milligram of nitrogen per cubic meter; abscissa, concentration of
phosphate, units miligram P2O5 per cubic meter. The lines correspond to ration of ΔN : ΔP of 20:1 milligram atoms.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
12
The establishment of a general, if approximate, relation between the concentration of the various
organic derivatives in sea water and the chemical composition of plankton would provide a valuable tool
in the analysis of many oceanographic problems. Observations made at a single group of stations such
as that reported cannot be considered to establish such a relation, though the results doubtless are
encouraging.
The data collected by the “Dana” (Thomsen, H., 1931) enable the generalization to be tested
more widely—at least so far as nitrate and phosphate are concerned, for the measurements were made
in the most diverse regions by the same investigators using uniform methods. In Fig. 4 I have plotted the
simultaneous measurements of phosphate and nitrate obtained by the "Dana" at all stations and depths
in the three oceans traversed. No attempt has been made to separate the data obtained at
different stations within each ocean, for, as in the case of the observations collected by the "Atlantis"
the water underlying a given station at various depths has quite different origins. It is apparent that a
definite correlation exists between the quantity of nitrate and phosphate occurring in any sample. The
proportions between these constituents, as indicated by the lines drawn through the points, are
essentially the same in the three oceans visited by the "Dana" and in the Atlantic stations occupied by
the "Atlantis".
The stations occupied by the "Dana" and the "Atlantis" were all in temperate or tropical
latitudes. In Fig. 5 are plotted data selected at random from the stations in Barents Sea, 70°-76° N,
reported by Kreps and Verjbinskaya (1932) and from stations in the south Atlantic Ocean between 55°
and 62° S. published by Ruud (1930). Here the proportions between phosphate and nitrate nitrogen vary
in the same ratio as in the more temperate waters found at low latitudes, though the quantities of these
constituents are much lower in the north than in the south.
These results indicate that the relations observed in the western Atlantic may be of general
application, at least so far as the oceanic waters are concerned. By inference they Suggest a remarkable
uniformity in the chemical compositionof the planktonic communities occupying the various oceans. It is
scarcely to be expected that these relations will hold in water bodies of limited extent, where local
conditions such
as the proximity of land, the inflow of rivers, and the peculiarities of a local flora and fauna may
alter the picture. Examunation of data for such regions as the Baltic (Buch, 1932), the Norwegian fjords

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
13
(Braarud and Klem, 1931), the Denmark strait (Bohnecke, Fgyn, and Wattenberg, 1932), indicate that
this is the case. In the English Channel the ratio in the variation in nitrate and phosphate in the surface
water with season was about 2 mg. nitrate nitrogen to 1 mg. P2O5, (ΔN:ΔP = 10:1 mg. atoms) according
to data published by Harvey (1928). Cooper (1933) has shown that in this region where active
regeneration takes place, variation in the ratio of nitrate to phosphate is attributable to the longer time
required to complete the regeneration of nitrate from decomposing albuminous matter. In the Gulf of.
Maine data recently secured by Dr. Rakestraw indicate that the ratio of the variation of nitrate and
phosphate with depth is lower and more variable than in the open ocean outside the Gulf. However, the
value of a generalization such as that suggested by the data from the open oceans lies in the fact that it
makes
clearer the exact nature of the anomalous conditions found in local situations and thus defines
more precisely the questions which must be answered before the local situation is understood. This
point can be illustrated by a consideration of the anomaly in the concentration of oxygen which is
present in the data secured by the "Atlantis".
Below 1,000 meters there is less oxygen removed from the water than is to be expected from
the amount of nitrate present. This expectation, however, is based on the assumption that the nitrate
has all appeared as the result of decomposition of organic matter after the water was removed from
contact with the atmosphere. The observations suggest that the deeper water of the Atlantic contained
a considerable amount of nitrate at the time it sank. Actually one must assume most of the samples
from the greater depths to have contained about 140 mg. nitrate nitrogen per cubic meter (equivalent
to 10 x 10-3 mg. atoms per liter) at the time they became separated from the atmosphere. Now the
water at these depths is thought to originate at high latitudes where nutrient substances are commonly
observed at high concentrations in the surface water. Thus Kreps and Verjbinskaya (1932) observed
nitrate nitrogen concentrations in the surface water of Barents Sea of 128 to 200 mg. per cubic meter in
March and April, and Bohnecke, Fgyn and Wattenberg (1932) record values of 125 mg. per cubic meter
in the mixed water of the polar front east of Greenland. The values of nitrate nitrogen recorded by Ruud
(1930) in the surface waters of the Antarctic exceed 600 mg. per cubic meter in many cases. Thus the
history of the deep water suggested in explanation of the anomalous character of the ratios in which
oxygen enters is confirmed by independent observations.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
14
Correlation between concentration of nitrate and phosphate in waters of
Barents sea (data of Kreps and Verjbinskaya) and south Atlantic (data of Ruud), from
stations between 55°-62°S., 0°-40° W. Ordinate, concentration of nitrate nitrogen,
units milligrams of nitrogen per cubic meter, abscissa, concentration of phosphate,
units milligrams P2O5 per cubic meter. The line corresponds to a ratio of ΔN : ΔP= 20:I
milligram atoms.
One fact of great general interest emerges from an examination of the data recorded in Figs. 1
and 4. It may be noted that as the quantities of nitrate and phosphate diminish, as they do as one
approaches the surface layers of the sea, they diminish simultaneously in such proportions that no great
excess of one element is left when the supply of the other has been exhausted. In 1926 Harvey wrote:
“It is a remarkable fact that plant growth should be able to strip sea water of both nitrates and
phosphates, and that in the English Channel the store of these nutrient salts, formed during autumn and

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
15
winter, should be used up at about the same time.” The relation noted by Harvey is thus of much wider
application than he could have known at that time. It appears to mean that the relative quantities of
nitrate and phosphate occurring in the oceans of the world are just those which are required for the
composition of the animals and plants which live in the sea. That two compounds of such great
importance in the synthesis of living matter are so exactly balanced in the marine environment is a
unique fact and one which calls for some explanation, if it is not to be regarded as a mere coincidence. It
is as though the seas had been created and populated with animals and plants and all of the nitrate and
phosphate which the water contains had been derived from the decomposition of this original
population. Professor Huntsman has suggested to me that the correspondence between the proportions
of phosphate and nitrate in the seas and the statistical composition of living matter may be due to the
fact that, although different members of the plankton community have different requirements in regard
to phosphorus and nitrogen, the numbers of each of these members may depend on the relative
availability of the substances they most need. Thus a population requiring relatively much nitrogen may
thrive until the nitrate supply has been depleted, when it will be replaced by a population requiring
relatively more phosphorus. By the balancing of such communities the ratio of the elements in the
plankton as a whole might come to reflect the ratio of the nutrient substances in sea water rather
closely.
Another explanation of the correspondence between the proportions of nitrate and phosphate
in the sea and the composition of living matter may be sought in the activities of those bacteria which
form nitrogenous compounds from atmospheric nitrogen or liberate nitrogen in the course of the
decomposition of organic matter. In the-case of the nitrogen fixing bactertum, Azotobacter, it is known
that for every unit of nitrogen fixed or assimilated and synthesized into microbial protein, about one half
a unit of P2O5 must be available. The physiological activity of such organisms must tend to bring the
relative proportions of organic nitrogen and phosphorus toward the ratio in which these substances
occur in the bacterial protoplasm. Comparable studies upon the physiology of the denitrifying bacteria
do not appear to have been made. It is evident, however, that the composition of these organisms must
be more or less fixed in regard to their relative phosphorus and nitrogen content and that when living in
an environment containing an excess of nitrate, considered in relation to phosphate, the growth and
assimilation of the organisms may continually tend to bring the proportions of nitrogen and phosphorus
nearer to that characteristic of their own substances. It would appear inevitable that in a world
populated by organisms of these two types the relative proportion of phosphate and nitrate must tend
to approach that characteristic of protoplasm in general and that, given time enough and freedom from

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
16
systematic disturbing influences, a relationship between phosphate and nitrate such as that observed to
occur in the sea must inevitably have arisen. On this view the quantity of nitrate in the sea may be
regulated by biological agencies and its absolute value determined by the quantity of phosphate
present.
These explanations are in no wise mutually exclusive nor do they exclude other possibilities.
Whatever its explanation, the correspondence between the quantities of biologically available nitrogen
and phosphorus in the sea and the proportions in which they are utilized by the plankton is a
phenomenon of the greatest interest.

AC Redfield, 1933, ON THE PROPORTIONS OF ORGANIC DERIVATIVES IN SEA WATER
17
LITERATURE CITED
Bounecxe, G., Foyn, B., and Warrenserc, H. 1932. Beitraége zur Ozeanographie des Oberflichenwassers
in der Danemarkstrasse, und Irminger See. Teil 2. Ann. Hydrogr. Berl., Bd. 60, S. 314.
Braarup, T., and Fayn, B. 1930. Beitrage zur Kenntnis des Stoff-wechsels im Meere. Avhandl. Norske
.Vidensk.-Akademi Mat. a Nat. Klasse, 1930, No. 14, pp. 1-24. Oslo.
----- and Kiem, A. 1931. Hydrographical and Chemical Investigations in the Coastal Waters off Mere and in the
Romsdalsfjord. Hvalrddets Skrifter Norske Vidensk.-Akademi, No. 1, pp. 1-88. Oslo.
Bucu, K. 1932. Untersuchungen ber geldste Phosphate und Stickstoffverbindungen in den Nordbaltischen
Meeresgebieten. Merentutkimuslaitoksen Julkaisu Havsforskningsinst. Skrift, No. 86,
pp. 1-30. Helsingfors.
----------, Harvey, H. W., Warrenserc, H., and GRIPENBERG, 5. 1932. Uber das Kohlensauresystem im
Meerwasser. Rapp. Cons. Explor. Mer., Vol. 79, pp. 1-70. Copenhague.
Cooper, LHN. 1933. Chemical Constituents of Biological Importance in the English Channel, Nov. 1930-Jan.
1932. J. Mar. Biol. Ass., ns., vol. 18, pp. 617-628. Plymouth.
Harvey, H. W. 1926. Nitrate in the Sea. Ibid., vol. 14, p. 71.
------- 1928. Nitrate in the Sea. II. Ibid., vol. 15, p. 183.
Kreps, E., and Verysrnsxaya, N. 1932. The Consumption of Nutrient Salts in Barents Sea. J. Cons. int. Explor.
Mer, vol. 7, pp. 25-46. Copenhagen.
Ruvup, J. T. 1930. Nitrates and Phosphates in the Southern Seas. Ibid., vol. 5, pp. 347-360.
THOMSEN, H. 1931. Nitrate and Phosphate Contents of Mediterranean. Water. Report on the Danish
Oceanographical Expeditions 1908-1910 to the Mediterranean and Adjacent Seas. No. 10, vol. 3, pp. I-II.