Untitled Document

2. Hydrochemical Investigations in the Arctic Ocean

| 2.1. History of Investigations
| 2.2. Methods of Measurement and Determination Accuracy.
| 2.3. References to Section 2

2.1. History of Investigations

Arctic seas of the Siberian shelf and the Arctic Basin were absolutely unexplored in hydrochemical aspect till the 20-s of the XX-th century. Some amount of determinations were made by expeditions of A. Nordenskiold on board of "Vega" (1878-1879), F. Nansen on board of "Fram" (1893-1896), H. Sverdrup and F. Malmgren on board of "Maud" (1918-1921).

Hydrochemical observations for parameters of sea water related with biochemical processes (nutrients, elements of the carbonate system) began in the 20-s because of fishery intensification. Amount of information significantly increased during the Second International Polar Year (1932-1933), and principle of international coordination was introduced in practice of investigations of the Arctic seas. Annual observations were carried out in the Chukchi Sea in the years 1932-1938 by Soviet and US expeditions.

Systematical hydrochemical study of the Kara and Laptev Seas began in the 30-s after establishment of the Main Administration of the Northern Sea Route. Study of the East Siberian and Chukchi Seas began somewhat later.

Materials collected up to the year 1941 by the marine expeditions of the Arctic Institute allowed to obtain the first comparative hydrochemical characteristics of the Arctic seas (for example, by then there were 10.000 determinations of dissolved oxygen and more than 12.000 determinations of alkalinity in the Kara Sea, and several thousand determinations in the Laptev and Chukchi Seas).

Cycles of limited in number, but, nevertheless, special observations were done in this period in some expeditions. These observations have been carried out in order to reveal influence exerted by ice melting and freezing on hydrochemical conditions of these seas, including chemical properties of sea ice, study of a possibility to use hydrochemical characteristics as reagents of water mass origin and propagation, study of river runoff influence on hydrochemical conditions of the seas. With this in mind, spatial distribution have been studied of alkaline and sulfate coefficients, pH, concentration of dissolved oxygen, as well as of complete set of nutrients and electric conductivity of sea water. These observations have given some material for estimation of daily and seasonal oscillations of hydrochemical element concentrations.

In particular, alkalinity increase of sea water were revealed both in melting zones, as well as in water areas with strong influence of river runoff. However, concentration of dissolved oxygen in the melting zones was increased in the surface layer because of intensive development of phytoplankton, production of oxygen, and often over-saturation of seawater by oxygen (Wiese, 1938). The author revealed that ice edge in the polar seas is a frontal zone according to hydrochemical and biological indications.

Selective rejection of salt out of brine captured by ice takes place by freezing and successive ice thickness growth, it causes a relative concentration decrease of carbonates and sulfates in surface waters. This fact is also approved by study of chemical composition of sea ice (Laktionov, 1930). Deterioration of normal relationships between salt components of seawater is a consequence of this fact.

By ice melting, these processes are reversal in those water areas, where the ice has drifted during polar winter (i.e. for 7-9 months).

Deficit of dissolved oxygen is observed in the water areas influenced by river runoff, because of inflow of a large amount of organic matters and intensive oxidation. As this takes place, active reaction of environment strongly shifts to the acid side (pH values decrease up to 7.5 and lower) (Laktionov, 1936).

Therefore, results of hydrochemical investigations of this period revealed wide possibilities for their implementation in diagnostics of water mass origin and dynamics in the Arctic seas and Arctic Basin.

A large amount of complete analysis of sea and salty water composition has also been performed. Using this material P. Lobza (1947) has studied a relationship between water salinity and chlorine concentration. She revealed significant deviations of the chlorine coefficient in the Arctic seas from the White Sea to the Chukchi Sea from that accepted in the formula of Knudsen-Sorensen for the ocean water (Fig.2.1):

S=0.030+1.8050Cl.

According to her determinations, there is a growth of the chlorine coefficient in the salty waters (S< 25 psu) from 1.807 by S=25 psu (it is for 0.002 higher than the value for the ocean) to 1.845 by S=10 psu. Therefore, salinity (and density) of the waters freshened by river runoff can be up to 2% higher, than it follows from the formula for the ocean. However, at a later time, interest to this problem has significantly weakened because of insufficient accuracy and labor-intensity of the used analytical methods.

Fig.2.1 Dependence of the chlorine coefficient KCl of water salinity in the Arctic seas influenced by river runoff.

| according to P. Lobza (1940)
| the formula of Knudsen-Sorensen
° | data of analytical determinations

Investigations were continued in the 80-s using high precision methods of determination of chloride activity in sea water (in particular, with the help of chloride electrodes (Melnikov, 1984; 1989). It has been found that noticeable oscillations of inter-element relationship appeared by low water temperatures (- 1.8 ÷4° C) exerting influence on accuracy of water salinity determination using two methods - electrometric and argentometric.

Both these methods give underestimated values for the surface waters (upper layer of 10 m) in all four Arctic seas in summer. Difference between actual and measured values can be rather significant: dispersion of the deviations is 0.03-0.12 psu for the first method, and 0.05-0.18 psu for the second one.

Chemical processes exert significant influence on relative composition of the surface waters in winter. These processes develop by ice formation and changes of ice cover state, for example, it is brine rejection in the under-ice water layer. That is why, both indirect methods of salinity determination give overestimated results. As this takes place, dS values exceeding 0.02 psu were observed in 30-40% of cases, they were equal practically to zero in 20-30% of cases.

Overestimated results are common in the waters of the Arctic seas underlying the upper layer of 10 m. However, errors do not exceed 0.02 psu in 80% of cases.

The hydrochemical observations were substantially reduced during the Second World War, they were continued only after the war in marine expeditions of the Arctic and Antarctic Research Institute (AARI).

Since 1946, the annual summer hydrochemical observations were performed in marine oceanographic expeditions "Ice Patrol" in the Arctic seas, at first in the Chukchi Sea and later on in the Kara, Laptev and East Siberian Seas. The observations were carried out at standard transects. Aspiration to unification of methods of chemical analysis of sea water, all-embracing character of investigations and their higher level were typical for the post-war period. Materials of these expeditions were used in many research works and became a basis for drawing of maps of mean distribution of hydrochemical parameters in the Arctic seas (Atlas of the Arctic Ocean, 1980; Atlas of the Arctic, 1985).

The most large-scale and systematic hydrochemical observations using a fixed grid were performed in the 70-s and in the beginning of 80-s according to the plan of the Natural Experiment in Study of Interaction of the Ocean and Atmosphere (Trioshnikov et al., 1968). In this period, hydrological and accompanying hydrochemical observations were organized as plan hydrological surveys of sea water areas. This work was carried out using vessels in summer and aircraft in winter, covering the entire sea water area and the Arctic Basin. Observations at "North Pole" drifting stations were continued simultaneously. Number of hydrochemical determinations increased in this period to several tens of thousand for previously poor covered areas. It allowed to study hydrochemical conditions in the seas, Arctic and North European Basin using a serious statistical basis.

The "Ice Patrol" marine expeditions were stopped in the 80-s. Summer observations in the Kara Sea were carried out by the research vessels "Academician Shuleikin" and "Professor Multanovsky". Summer surveys of ice free parts of the sea were completed by observations in sea ice made by the research icebreaker "Otto Shmidt". The vessels of the "Shuleikin" type were equipped by modern sounding complexes, plastic bottles were used for sampling, nutrient concentration in sea water was determined with the help of AutoAnalyzer AKEA. Use of modern analytical and sampling equipment allowed to improve significantly quality of hydrochemical information.

Vast amount of information on hydrochemical conditions in coastal and river mouth zones of the Arctic seas was collected by sledge-tractor expeditions of Arctic departments of the USSR Hydrometeorological Service and in coastal observatories (Zubakina, 1974, Miskevich, 1979, Sidorov, 1992).

It should be mentioned that chemical analysis of water samples were performed using unified instructions. It guaranteed comparability of data obtained in different expeditions.

International cooperation in study of the Arctic seas received wide impetus in the 90-s. Several Russian-Norwegian and Russian-German expeditions were carried out in the Kara Sea. Russian-French expeditions SPASIBA (Letolle et al., 1997) worked in the Laptev Sea in September 1989 and in August-September 1991. A series of multidisciplinary Russian-German expeditions was performed in the Laptev Sea in 1992-1999 in accordance with the program "Laptev Sea System", some of these expeditions were unique (Kassens & Karpiy, 1994; Kassens & Dmitrenko, 1995). This expedition for the first time was carried out in autumn in 1995 in the period of intensive ice formation (Kassens, 1997). In 1996 propagation of river water in seashore near estuary during flood on Lena was studied for the first time (Dmitrrenko et al., 1999). Joint US-Russian expeditions with participation of Japanese specialists were performed in this period of time in the Chukchi Sea and in the eastern part of the East Siberian Sea. The main specific feature of the expeditions in this period of research is simultaneous collection of information in different branches of science and study of the Arctic seas as unit systems.

Of course, data of expeditions performed in different years are not of the same quality. Information obtained since the 60-s is more reliable, because of presence of a definite experience of hydrochemical observations in the Arctic, and implementation of optical devices instead of the visual methods of analysis. The most accurate data have been obtained in the expeditions on the vessels of the "Shuleikin" type and in international expeditions in the 90-s.

There were no foreign publications in hydrochemistry of the Russian Arctic seas till the middle of the 90-s. Foreign research vessels have worked usually in the Chukchi and Beaufort Seas. However, a US icebreaker made an oceanographic survey in the East Siberian and Laptev Seas in the summer of 1963, and in the Kara Sea in 1965. Results of these observations have been later published (Codispoti & Richards, 1968). Nevertheless, many scientists were interesting in processes on the wide Siberian shelf (Anderson, 1995; References to this Section). Problems of biological productivity of the Arctic seas have attracted a maximum attention, as well as influence of river runoff (Anderson et all., 1983; Schlosser et all., 1994; Dai & Martin 1995 and others), interaction of the shelf and the Arctic Basin (Legendre et all., 1996; Schauer et all., 1997).

International cooperation in study of the Kara and Laptev Seas has given results. New data have been obtained on water mass distribution in the northern troughs of the Kara Sea (Augstein, 1997; Pivovarov et al., 1999). The hydrochemical observations performed in the Russian-French expeditions SPASIBA were used in a number of articles devoted to influence of the Lena river on the south-eastern part of the Laptev Sea.

The most complete review of investigation results of hydrochemical water structure of the marginal Arctic seas of the Siberian shelf and of the Arctic Basin were made by V. Rusanov et al. (1979), geochemical processes in the Eurasian shelf seas were studied by Ye. Romankevich et al. (1982) and V. Smagin (1995). Hydrochemical division into districts for these water areas has been carried out, and variability limits of the main hydrochemical elements and their structure have been determined.

2.2. Methods of Measurement and Determination Accuracy.

Hydrochemical Atlas of the Arctic Ocean unites data collected in expeditions of different scientific and industrial organizations of different countries for a long period of time. Naturally, methods of chemical analysis of seawater were constantly refined during such a long period of time. Chemical analysis of sea water was performed in the USSR using unified instructions and standard methods which had been elaborated in the following methodical centers: the State Oceanographic Institute (SOI), the Hydrochemical Institute (HCI), the Arctic and Antarctic Research Institute (AARI), and others. It ensured the possibility to compare data obtained in different expeditions by different organizations.

These instructions for performance of chemical analysis of sea water were periodically changed, because of perfection of analytical equipment and in order to meet more strict requirements to determination accuracy and to ensure consistency of the Russian methods with the international standards. These changes can be traced analyzing successive editions of the "Guidance for Chemical Analysis of Sea Waters" published in 1950, 1959, 1977, 1993, however, the principle remains invariable that all the observations regardless of expedition or region of field work should be carried out using the last accepted "Guidance" or "Guiding Document".

As a rule, concentrations of only main biohydrochemical indices were determined in the Arctic expeditions from all the variety of chemical elements and their compositions dissolved and suspended in seawater. They are as follows: nutrients (dissolved mineral forms of nitrogen, phosphorus, silicon), dissolved oxygen and some parameters of the carbonate system (pH and alkalinity). Choice of these chemical elements and parameters was determined by the fact that they were used for estimation of biological productivity of marine environment, and that many of them were indicators of water mass origin.

The Winkler method (Guidance 1993), which had shown itself to advantage, was used for determination of oxygen. Measurement error within the range of concentrations typical for the Arctic seas does not exceed 0.05 ml/l, the total error equals 3.4%. Tables of oxygen solubility in sea water have varied repeatedly in the course of long period of observations. It made difficult to perform joint analysis of the data obtained in different time. Calculations of sea water saturation by oxygen in the Hydrochemical Atlas of the Arctic Ocean were carried out using the formulas recommended by the Oceanographic Commission according to the UNESCO formula (Tables 1976).

Mineral nutrients are a nourishment base for life of phytoplankton. Dissolved inorganic forms of nitrogen (nitrites, nitrates, ammonium nitrogen), phosphorus (phosphates) and silicon (silicates) are the most important for algae.

Nitrite concentration was determined in seawater using the colorimetric method. Nitrite concentration is not high, therefore analysis error can be 20% and above. For determination of nitrate concentration, the method was used of their reduction to nitrite in a column of coppered fine-crystalline cadmium with subsequent determination of nitrite concentration using the colorimetric method. The total error within the range of concentrations observed in the Arctic seas varies from 3.1 to 7.4% (Guidance, 1993). The method error does not exceed 4.4% while using Autoanalyzers.

Ammonium nitrogen was determined using the colorimetric method with the total error varying from 2.8 to 11.4% within the range of concentrations from 15 to 500 µg/l.

Concentration of inorganic silicon dissolved in sea water was determined using the colorimetric method and scale of colors with errors up to 20% and above (Guidance 1954) and device methods with errors 4.6-5.8% depending on concentration (Guidance 1993). Use of AutoAnalyzers allowed to obtain a higher accuracy and presentation of results (Koroleff 1983).

Concentration of dissolved inorganic phosphorus (orthophosphate) and total phosphorus was determined in seawater (Guidance, 1993). Error of the colorimetric analysis equals 4-5% depending on concentration and used devices. The term "phosphate" is often used in scientific literature on chemical oceanography instead of the term orthophosphate as a synonym.

The carbonate system of sea water is a buffer system, it supports a weak alkaline medium and plays a significant role in hydrobiological and physiological processes.

A pH scale with a set of indicators was usually used for pH determination in sea water (The Buch method). Accuracy of pH determination was significantly improved with implementation of potentiometers in practice of hydrochemical observations. The total error equals 0.04 conventional units (Guidance, 1993).

The volumetric-analytical and potentiometric methods were used for determination of total alkalinity of sea water. Error of these methods is about 0.5% (Guidance, 1993). The alkaline-saline coefficient and relative alkalinity are ratios of the total alkalinity to salinity and chlorinity of sea water, respectively. These indices were taken up in chemical oceanography, because using their values one can differ sea freshening caused by river runoff and that caused by precipitation and ice melting.

These indices were taken up in chemical oceanography, because using their values one can differ sea freshening caused by river runoff and that caused by precipitation and ice melting.

Detailed information about instructions and Guiding Documents used by investigators for performance of chemical analysis in specific expeditions or research vessel cruises are given below in Table 2.1.

It should be mentioned that there were some specific conditions of performance of hydrochemical observations in the Arctic. These conditions might cause violation of methodical requirements and appearance of systematic and accidental errors. They are as follows: severe climatic conditions, insufficiently well equipped ship laboratory, especially at small ships; overtime of analysts, and others. In the airborne "Sever" expeditions, water samples were analyzed in base laboratories 6-12 hours after sampling, and often transportation of the samples took much more time. Therefore, information about laboratory was certainly recorded in books for registration of primary hydrochemical observations. All the hydrochemical observations were subjected to a strict control and estimation by a methodical commission of the AARI hydrochemical laboratory.

List of instructions and methods used for hydrochemical determinations are given in Tables 2.1 and 2.2. The table "Information on methods of hydrochemical analysis used in expeditions of the AARI and other organizations in the Arctic Ocean" is given in Appendix1 . Name of these expeditions, period of their performance, name of research vessel or other platform and number of stations carried out in each expedition are given in this table. Numbers divided by oblique stroke are given in the columns related with hydrochemical parameters. The left side gives a number of used guidance, instruction or other methodical document (Table 2.1), the right side gives a method number for determination of this specific element (Table 2.2) mentioned in the guidance.

Table 2.1

List of guiding documents and instructions used by hydrochemical investigations.

No. | Guidances, instructions
1 | Instruction for performance of hydrochemical investigations of sea water. The Main Administration of the Northern Sea Route, M. 1944
2 | Guidance for chemical analysis of sea waters (edited by P. Voronkov). Hydrometeoizdat, L. 1950
3 | Guidance for chemical analysis of sea waters. Published by the Main Administration of the Northern Sea Route, 1954
4 | Guidance for marine hydrochemical investigations. Hydrometeoizdat, L. 1959
5 | Guidance for methods of chemical analysis of sea waters. Hydrometeoizdat, L. 1977
6 | Methodical instructions No. 30 SOI, M. 1966
7 | Provisional instruction for determination of nutrients. AARI, 1968
8 | Instruction for determination of silicon in sea water. AARI
9 | Provisional methodical instructions for quantitative determination of mineral phosphorus in sea water. SOI, M. 1971
10 | Provisional methodical instructions for quantitative determination of silicon (with chlorine tin) in marine environment. SOI, M. 1971
11 | Provisional instruction for quantitative determination of dissolved oxygen in sea water. SOI, M. 1972
12 | Provisional methodical instructions for determination of oxygen in the Arctic waters. AARI
13 | Instruction of the All-Union Arctic Institute. Kondyrev, Bruevich
14 | Instruction for hydrochemical determinations in the sea. S. Bruevich, 1938
15 | Guidance for chemical analysis of sea waters. St. Petersburg, Hydrometeoizdat, 1993, GD 52.10.243-92

Table 2.2

Methods of chemical analysis

Hydrochemical parameters and methods of their analysis
Oxygen
1 | Iodinemetric (the Winkler method)
pH
1 | Colorimetric
1/a | Subjective (standard scale)
2 | Electrometric (pH-meter)
Total alkalinity
1 | Automatic titration with HCl (Acidometric, Volumetric-analytical method)
2 | Back titration method
3 | Electrometric (pH-meter)
Phosphate
1 | Colorimetric (color equalization according to the Denige-Atkins with chlorine tin)
1/a | Subjective (Gener's cylinder)
1/b | Objective (photoelectrocolorimeter (PEC), spectrophotometer)
2 | Colorimetric (according to the Morphy-Riley with ascorbic acid)
2/a | Objective (photoelectrocolorimeter, spectrophotometer)
Silicate
1 | Colorimetric (according to the Dienert-Wandenbulke method with Moor salt)
1/a | Subjective (Gener cylinder)
1/b | Objective (photoelectrocolorimeter, spectrophotometer)
2 | Colorimetric (All-Union Institute of Fishery and Oceanography) - PEC
3 | Colorimetric (Mullin-Riley for small concentrations) - PEC
4 | Autoanalizer AKEA (DATEX manual)
Nitrite
1 | Colorimetric (color equalization according to the Griss-Ilosway method)
1/a | Subjective (Gener cylinder)
1/b | Objective (photoelectrocolorimeter, spectrophotometer)
2 | Autoanalizer AKEA (DATEX manual)
Nitrate
1 | Colorimetric (dephenilamin oxidation method)
1/a | Subjective (standard scale)
2 | Colorimetric (reduction using the methods of Wood, Armstrong, et al.)
2/b | Objective (photoelectrocolorimeter, spectrophotometer)
3 | Autoanalizer AKEA (DATEX manual)

For example, numbers "4/1b" in the column of silicon determination (Si) means the following. The chemical analysis has been carried out in accordance with the Guidance for marine hydrochemical investigations (Hydrometeoizdat, L. 1959) given in Table 2.1 as number 4, the measurements have been made using the colorimetric method (color equalization according to the Dienert-Wandenbulke with Moor salt), in doing so, the measurement of optical density has been performed using photoelectrocolorimeter or spectrophotometer (see Table 2.2, column "silicate", item 1b).

2.3. References to Section 2

- Anokhin V.N., Melnikov S.A.: Physical-chemical properties of sea water and variation of its salt composition in the under-ice layer. - In: Vertical structure and dynamics of the under-ice layer. Hydrometeoizdat, L., 1989, pp. 25-35.
- Wiese W.Yu.: Hydrochemical conditions in the marginal ice zone of the Arctic seas. - Problems of the Arctic, 1943, No. 2, pp. 13-31
- Zubakina A.N.: Some hydrochemical specific features of estuary zones of Anabar, Lena, Yana, Indigirka. - Proc. of the SOI, 1974, v. 118, pp. 44-55
- Lobza P.G.: Chemistry of the Kara Sea. Skeleton of the salt composition. - Proc. of the AARI, 1947, v. 197, 180 p.
- Laktionov A.F.: Hydrochemical conditions in the Laptev Sea. 1936
- Laktionov A.F.: On properties of sea ice. - Proc. of the Institute of North Investigations, 1930, v. 49
- Melnikov S.A.: Study of concentrations of some elements of salt composition in the waters of the shelf zone of the East Siberian Sea using ion-selective potentiometry. - Pro. Of the AARI, 1984, v. 368, pp. 87-98
- Miskevich I.V.: Extremely low levels of oxygen concentration in the waters of estuary sea-shore of the Lena delt. - Deposited in the All-Union Institute of Scientific and Technical Information - International Data Center, 1979, 10p.
- Trioshnikov A.F., Borisenkov Ye.P., Nikiforov Ye.G., Mustafin F.M., Chaplygin Ye.I., Spaikher A.O.: Natural experiment in study of interaction of the ocean and atmosphere. - Problems of the Arctic and Antarctic, 1968, v. 28, pp. 5-20.
- Romankevich Ye.A., Daniushevskaya A.I., Beliaeva A.N., Rusanov V.P.: Biochemistry of organic matters in Arctic seas. - "Nauka", M., 1982, 240p.
- Rusanov V.P., Yakovlev N.I., Buynevich A.G.: Hydrochemical conditions of the Arctic Ocean. - Proc. of the AARI, 1979, v. 365, 144 p.
- Sidorov I.S., Gudkov A.Yu.: Influence of oxygen regime on living conditions of zoobenthos in coastal regions of the Laptev Sea. - Oceanography, 1992, v.32, No.5, pp. 902-904.
- Smagin V.M.: Hydrochemical investigations of polar regions. - Problems of the Arctic and Antarctic, 1995, v. 70, pp. 183-192.
- Anderson L.G., Dyrssen D., Jones E.P., Lowings M.G. Inputs and outputs of salt, freshwater, alkalinity, and silica in the Arctic Ocean // Deep-Sea Res. - 1983. - No. 1. - P. 87-94.
- Anderson L.G. Chemical oceanography of the Arctic Ocean and its shelf seas // In: Arctic Oceanography: Marginal ice zones and continental shelves coastal and estuarine Studies. - 1995. - Vol. 49. - P. 183-202.
- Augstein E. (Ed.) The expedition ARCTIC '96 of RV "Polarstern" (ARK XII) with the Arctic Climate System Study (ACSYC) // Reports on Polar Research. - 1997. - No. 234. - 54 p.
- Codispoti L.A., Richards F.A. Micro-nutrient distributions in the East Siberian and Laptev seas during summer 1963 // Arctic. - 1968. - No. 21. - P. 67-83.
- Kassens H., Karpiy V.Y. Russian-German cooperation: The Transdrift I expedition to the Laptev Sea // Reports on Polar Research. - 1994. - No. 151. - 168 p.
- Kassens H., Dmitrenko I. The TRANSDRIFT II Expedition to the Laptev Sea // Reports on Polar Research. - 1995. - No. 182. - P. 1-180.
- Kassens H. (Ed.) Laptev Sea System: Expeditions in 1995 // Reports on Polar Research. - 1997. - No. 248. - 210 p.
- Legendre L., Rivkin R.B., Michel C. Food web structure and biogenic carbon export on the continental shelves of the Arctic Ocean // Mem. Nat. Inst. Pol. Res. - 1996. - No. 51. - P. 41-65.
- Letolle R., Martin J.M., Thomas A.J., Gordeev V.V., Gusarova S., Sidorov I.S. 13O abundance and dissolved silicate in the Lena delta and Laptev Sea (Russia) // Marine Chemistry. - 1993. - No. 43. - P. 47-64.
- Pivovarov S.V., Holemann J.A., Kassens H., Antonow M., Dmitrenko I. Dissolved oxygen, silicon, phosphorous and suspended matter concentration during the spring breakup of the Lena River. - In.: H. Kassens et al., (Eds.) Land-ocean system in the Siberian Arctic: dynamics and history. Springer. - 1999. - P. 251-264
- Schauer U., Muench R.D., Rudels B., Timokhov L. Impact of Arctic shelf waters on the Nansen Basin intermediate layers // Journal of Geophysical Research. - 1997. - Vol. 102. - No. C2. - P. 3371-3382.
- Schlosser P., Bauch D., Fairbanks R., Bonisch G. Arctic river-runoff: Mean residence time in the shelves and in the halocline // Deep-Sea Res. - 1994. - Vol. 41. - No. 7. - P. 1053-1068.
- Wiese,W. Zur Kenntnis der Salze der Meeresises - Annal. der Hydrol. und marit. Meteorolog., 1930.