E C O L O G Y A N D T H E P R O B L E M S OF W O R L D O C E A N

INTEGRATED

GLOBAL MONITORING YU. A. I Z R A E L

U.S.S.R. State Committee for Hydrometeorology and the Control of the Natural Environment and A.V. TSYBAN

Natural Environment and Climate Monitoring Laboratory under U.S.S.R. State Committee for Hydrometeorology and the Control of the Natural Environment, and U.S.S.R. Academy of Sciences

(Received June 1984) Abstract. Modern ecological state of the World Oceans is analysed, stressing the need for organization

and development of a scientific basis for global ocean monitoring. The tasks and basic principles of integrated global ocean monitoring are described. Complex of natural processes determines the assimilative capacity of marine ecosystems, which can serve as a basis for the study of ecological reserves of the World Oceans and ecological rationing of the anthropogenic impact.

A broad spectrum of investigations aimed at the evaluation of the role of the ocean in the geophysical and biological processes occurring on our planet and that of large-scale ecological problems, the assessment of the state of pollution, the determination of the adverse effects of the anthropogenic impact and forecasting the salubrity of the World Ocean are among the most urgent problems confronting modern society. They attract widespread attention by the community of scientists all over the world and acquire a keen international character. The oceans cover 70~ of the Earth's surface and interact actively with other spheres of the natural environment. These are the processes of the ocean-atmosphere interaction, to a great extent determining the climate (and, hence, biological processes) of our planet, the biochemical cycles of most of the important chemical elements closely related to the circulation of energy and the substance in natural photosynthetic activity of algae regulating the oxygen-carbon dioxide balance and other global phenomena. Meanwhile, the anthropogenic load on the World Ocean nowadays creates a stressed ecological situation in a number of its areas and can affect the ecological situation of the whole planet. Fields of chronic pollution and concentrations of heavy metals, petroleum and chlorinated hydrocarbons critical for the normal ecosystem functioning appear in the affected zones of the Ocean. Anthropogenic pollutants are becoming a powerful constantly acting ecological factor producing an effect on marine ecosystems, due to which their functioning, and first of all the production of organic matter, are exposed to the ever-growing anthropogenic impact [2]. Ensuing from an urgent need to isolate man-made changes in the structure and Environmental Monitoring and Assessment 7 (1986) 5-23. 9 1986 by D. Reidel Publishing Company.

6

YU. A. IZRAEL AND A.V. TSYBAN

functioning of marine ecosystems and to regulate the antrhopogenic impact on the World Ocean, a demand arose for the organization and realization of integrated global ocean monitoring. In the last decade, a concept of the integrated global monitoring of the biosphere was advanced by a number of scientists [7]. Soviet scientists contributed much to the development of this concept which is noted in the UNEP Publication 10 Years After Stockholm. The concept is considered in numerous publications including those by the authors of the present paper. It was discussed, among other things, at the international symposia on integrated global environmental monitoring in the town of Yurmala (U.S.S.R.) in 1979 and Tbilisi (U.S.S.R.) in 1981. The system of monitoring the antrhopogenic impact on the natural environment, and its consequences, is, as stated in our works earlier, of multipurpose informative character [7]. The system is supposed to comprise observations, estimations and forecasts of the biosphere, analysis of the extent of the impact on the environment, isolation and assessment of the impact factors and sources. Monitoring is a most important element in the process of understanding the biosphere, and of evaluating and forecasting its health, as well as in the strategy of regulating the environmental state. World Ocean integrated global monitoring occupies a specific place within the system of biosphere monitoring since it contemplates the assessment and forecasts of the state of the most important sphere covering two thirds of the surface of the globe, and its huge ecosystem, and has as its ultimate aim the conservation of the biological resources of the ocean and the protection of its health. Over the past decade, quite a number of countries initiated broad investigations of water circulation in the World Ocean, of the state of its pollution and of the interaction processes between the ocean and the atmosphere; the study of the ecological and physical consequences of ever-growing anthropogenic impact on the ocean environment has been carried out. Problems related to the monitoring of the pollution of the World Ocean and the health of its ecosystems are the subject of study included in a number of national and international programmes implemented within the framework of the United Nations Environment Programme (UNEP), the International Council for the Exploration of the Sea (ICES), the World Meteorological Organization (WMO), the International Oceanographic Commission (IOC) and the Council for Mutual Economic Assistance (CMEA). Integrated global ocean monitoring assumes a new importance in connection with the implementation of the World Climate Programme. Within the framework of this programme much consideration is given to the study of the dominating effect of ocean properties and dynamics on global cycles of heat, water and various chemical elements, especially those of carbon, in the climate system. In the U.S.S.R., the ecological basis for ocean monitoring is developed in the process of investigating pollution and its adverse ecological effect, which was carried out at institutions under the U.S.S.R. State Committee for Hydrometeorology and

ECOLOGY AND PROBLEMS OF WORLD OCEAN INTEGRATED GLOBAL MONITORING

7

the Control of the Natural Environment, the U.S.S.R. Academy of Sciences, the Academies of the Soviet Socialist Republics, the Ministry of Higher and Special Secondary Education, the Ministry of Fisheries and the Ministry of Water Management and Reclamation of the U.S.S.R. Development of integrated global ocean monitoring in the modern situation seems of most importance for taking effective measures directed to the conservation of the biological resources of the oceans.

1. Integrated Global Ocean Monitoring Integrated global ocean monitoring includes the ecological and physical aspects of monitoring. Ecological ocean monitoring is a system of analysis, assessment and forecast of the state of marine ecosystems. Analysis of ecological situations in the ocean implies two basic components: the determination of man-made changes in the conditions of the environment and the investigation of the ecological consequences of the impact of pollutants, including geochemical and biological effects, at individual and population-biotic levels. The main objectives of ecological monitoring are as follows: - to distinguish natural changes from those provoked by anthropogenic impact; - to relate effects in an ecosystem, particularly in the biotic component, to the level of environmental pollution, and to forecast the trend of their change; - to isolate 'critical' impact levels and the most valuable links in the biological chain of marine organisms; - to organize a system of observing the impact factors and ecological effects of pollution; and - to develop scientific principles for the organization of a system regulating the anthropogenic impact on the ecosystems of the ocean in different geographical zones.

Physical monitoring is a systematic analysis and control of thermohydrodynamic and pollution-spreading processes determining the ecological situation in the ocean. The main aspects of this analysis imply the theoretical and experimental study of the hydrophysical characteristics determining the hydrological situation and making possible the forecast of the state of ocean ecosystems. Integrated global ocean monitoring includes a system of physical, chemical and biological indices intended for a comprehensive analysis of the ecological situation and its effect on the climate, as well as assessment of the salubrity, of the World Ocean. It should also be noted that global ocean monitoring is not to be considered as an extension of regional monitoring to the water area of the World Ocean or as a sum of regional evaluations of the state of individual marine ecosystems. The main objectives of integrated global monitoring comprise the following.

8

YU. A. IZRAEL AND A.V. TSYBAN

(a) Investigation of most of the important physical processes affecting the distribution of anthropogenic pollution in the World Ocean. 0a) Determination of the effect of pollutants spread in the ocean on the most important geophysical processes occurring in the ocean and the atmosphere, and on the state of the climate system, and finally on the Earth's climate. (c) Investigation of the most important ecological processes characterizing the level of ocean pollution, its adverse effects and the activity of natural 'self-purification'. (d) Organization of a system of ecological regulation of the anthropogenic impact on the World Ocean in its different geographical zones.

2. The Modern Ecological Situation in the World Ocean

Pollutants released into the World Ocean spread in it irregularly forming zones with higher levels in coastal areas, the photic layer and around hydrofronts, where the bulk of living matter is concentrated, as well as in external sea contours and interfaces, where chemical reactions proceed actively and most powerful biocenoses are developed. At present, anthropogenic activity has a pronounced effect on the input of numerous chemical compounds into the marine environment. The anthropogenic component of discharge of a number of pollutants (Pb, Hg, oil, As, and CO2) is estimated in recent years to be either equal to, or even more than, the natural influx of those elements to the World Ocean (Table I). TABLE I Anthropogenic load on the World Ocean broken down in the order of priority of the pollutants [4] Marine pollutants

World production (t y r - l)

Natural component from runoff (t y r - ~)

Anthropogenic component (t y r - I )

Pb Hg Cd PCB Oil

3.5• 6 1.6x104 1.7x10 4 5 . 0 x 104 2.6x10 9

1.8• 2.1x10 6 3.0x10 3 7.0x103 1.7x104 1.7x104 7.0•215 9.5• 5 9.6• 6

Anthropogenic component in percent

R u n o f f of the ocean, t y r - l Direct pollution land component

92 70 50 100 91

1.0 x 10s...2.0 • 5.0 x 103...8.0 x 1.0• 103...2.0x 5 . 0 x 103...1.0x 5.0 x106...1.0 •

Atmospheric fallout

106 103 104 104 ~

2.0 x 105...2.0 x 2.0 x 103...3.0 x 5 . 0 x 103...1.4x 2 . 0 x 103...3.0x 6.0x103

106 103 104 103

Thus, dynamic properties of the ocean environment and a collection of constant, more essential physical phenomena determine the characteristic features of the modern ecological situation in the World Ocean. These are as follows. (1) Transport of technogenous particles by intensive currents for long distances

E C O L O G Y A N D PROBLEMS O F W O R L D O C E A N I N T E G R A T E D GLOBAL M O N I T O R I N G

9

and in high seas and damage of more vulnerable ecosystems, such as coral reef, upwelling, northern ecosystems and others at an early stage of development. (2) Formation of chronic pollution fields in the zones of convergence of heterogenous water masses and structural currents, estuarine zones and those of quasistationary cycles. These regions, as well as easily vulnerable ecosystems, may be classified conventionally as zones of the World Ocean subjected to ecological stress. (3) Transport of technogenous particles to deeper ocean layers and their accumulation in marine organisms and suspended organic matter. Such phenomena result in the formation of critical concentrations of petroleum and chlorinated hydrocarbons and toxic metals in coastal and off-shore areas. This is accompanied by disturbances in the functioning of the biotic component of marine ecosystems in the zones of chronic environmental pollution, leading to disturbances in the mechanism of most important biological and geochemical processes governing the 'self-purification' of the marine environment, i.e. suppression of the activity of marine microbiocenoses, accumulation of chemical toxicants in marine organisms and decrease of their ecological value, extinction of certain species and disturbances in organic matter production. The suppression of photosynthetic activity of algae, that can induce changes in the oxygen-carbon dioxide balance, is the most dangerous. This, in its turn, might adversely affect the planetary climate processes. The interrelation between physical and ecological (geochemical and biological) phenomena occurring in the ocean is an inalienable property of marine ecosystem functioning and deserves a far more thorough consideration than it is given here. Among numerous pollutants entering the World Ocean, the most dangerous are petroleum and chlorinated hydrocarbons, namely: pesticides, pyluchlorinated biphenyls (PCB), as well as toxic metals, first of all Hg, Ca, and Pb, i.e. the chemical compounds that have global spreading, continuous flux and pronounced adverse effects on marine organisms and populations. Pesticides and other xenobiotics even in very small concentrations are toxic and unfamiliar to marine organisms from the viewpoint of evolutionary experience. At present, more and more dangerous pollutants are found in the ocean, for example, polychlorinated and chlorinated terpenes, nitrosamines and others. Problems of microbiological pollution of inland seas and coastal zones of the ocean are becoming more and more acute. Considerable amounts of accumulated chemical toxicants were found in hydrobionts, bottom deposits and suspended matter in inland and fringing seas subjected to the antrhopogenic impact (for example, the Baltic, Mediterranean, and North Seas). 3. The Role of Atmospheric Transport in World Ocean Pollution

The ocean surface, and thin atmospheric layers that are in contact with it, form an original microecosystem. Its functioning determines the exchange of liquid and

10

YU. A. IZRAIEL AND A.V. TSYBAN

gaseous matter between the ocean and the atmosphere. This microecosystem is populated with specific communities of organisms: neuston and pleuston. A theory has lately been suggested that atmospheric transport and deposition of chemical substances to the water surface are among the most significant, constantly moving sources of World Ocean pollution. It was found in a number of investigations that lead, mercury and other heavy metals as well as DDT, PCB, low-molecular petroleum hydrocarbons and other organic substances in the gaseous phase or suspended state (particles and solid salts) are carried by air flows for tens of thousands of kilometers to the most distant areas of the ocean. This phenomenon is only a part of long-range atmospheric transport. The latest investigations by Japanese scientists should be mentioned in this connection. They showed that the atmospheric transport of dust containing high concentrations of biogenous elements is responsible for a powerful plankton bloom in the off-shore areas of the Pacific Ocean. Below are riven the yearly amounts of toxicants precipitating from the atmosphere on the surface of the World Ocean (Table I). The contribution of atmospheric transport to World Ocean pollution is supposed to be equal to that of river runoff. An undoubtedly significant problem of modern society is the transport of SO2, 'acid' rain and its significant impact on vegetation and fresh water ecosystems. Not going into the details of this phenomenon, it should be noted that 'acid' rain may have an adverse effect on biological and chemical processes occurring in the near-surface ecosystem, particularly in semi-closed brackish seas, like the Baltic Sea, as well as in the systems of fjords with low salinity where surface waters are continuously saturated with fresh water. The problem of pollution at the ocean-atmosphere interface should be given due consideration. Vast water areas of the ocean are usually covered with an oil film, and the surface microlayer is polluted with oil aggregates. Their concentrations are very high in certain regions, for example, 100 mg m -2 (south of Japan), 500-600 mg m - 2 (in the Mediterranean) and even 2000 mg m - 2 in the North Atlantic near the Strait of Gibraltar. The total amount of pelagic aggregates in the World Ocean is estimated to be as high as 700 000 tons. Accumulation of stable oil aggregates possessing toxic and carcinogenic properties in surface films is particularly dangerous. Polycyclic aromatic hydrocarbons may be related to this group. Recent investigations have revealed that benz(a)pyrene is widespread in the World Ocean [26]. The highest concentration of this stable carcinogenic hydrocarbon is often found to be related to the thin surface microlayer of the Ocean. In various regions of the World Ocean, such as the Baltic Sea, North Atlantic and North Pacific, coefficients of benz(a)pyrene accumulation in the surface film were K 2 - K 20. Of interest is the regular increase of benz(a)pyrene concentration in the surface film of the Bering Sea - one of the cleanest regions of the Pacific. Considerable BP concentration was even found in off-shore areas of the Bering Sea.

ECOLOGY AND PROBLEMS OF W O R L D OCEAN INTEGRATED GLOBAL MONITORING

11

Organic films of natural and anthropogenic origin affect quite a number of geophysical, chemical and biological processes of the ocean-atmosphere interaction. Pollutants incorporated in surface films are in contact with neuston organisms that populate the near-surface biotope of the oceanic pelagial. This is one of the hazardous effects of pollution since the neuston biocenosis includes abundant populations of marine organisms, a great many of which are at an early stage of ontogenesis, and abundant microbial populations playing an important part in the oxidation of organic matter on the ocean surface.

4. The Biological and Ecological Effects of Pollutant Impact on Marine Organisms and Biocenoses Modern conceptions of ecological effects produced by marine pollution have only recently begun to take shape. The diagram in Figure 1 summarizes the existing effects of anthropogenic impact.

I

cation ~ Eutrophi-

Ec~ disbalance

~

Redtides

AnaerObiO$i$ of the environment v I

Biologicaleffectsat populational andcommunitylevel Biologicaleffectsat the organismallevel Accumulationof pathogenic microfloraby filteringhydrobionts Immunologicaleffects

Lossof several species

I

~ [ v

Genetic) physiological, biochemical, morphological consequences

Hygienic consequences

Fig. 1. EcologicalConsequencesof Ocean Pollution

Numerous effects manifest themselves more vividly against the background of naturai variations and particularly so under the conditions of extreme anomalies (Figure 1). That is why one of the most important objectives of integrated global ocean monitoring consists in developing a system of long-term observations that would make it possible to distinguish anthropogenic changes against the background of natural variations.

12

YU. A. IZRAEL A N D A.V. TSYBAN

Negative anthropogenic effects show themselves at individual (biological consequences) and population-biocenotic (ecological consequences) levels. Primary critical disturbances of the functioning of hydrobionts under the impact of pollutants are directly expressed at the level of biological effects. These disturbances consist in changes of the cellular chemical composition, the character of ferment systems, respiration processes, osmotic-regulation, growth and multiplication, formation of mutations, carcinogenesis and pathological forms, changes of cell size, the disturbances of motion and orientation in space. These are the consequences of biochemical, morphological, ecological, physiological and genetic character. The stable changes in the structure and functioning of marine biocenoses show up in the following processes: alteration of the mean biomass of plankton populations and benthic organisms; reduction of the number of higher taxons - genera or families of hydrobionts; emergence of organisms new for the marine environment; alteration of relations between the numbers of individual taxonomic groups of hydrobionts; alteration of relations between the processes of production and destruction of organic substances; distrubances in the processes of ecological metabolism; and emergence of antibiotics-resistant forms of microorganisms. Impact of toxicants has become a powerful evolutionary factor under the conditions of the present state of the World Ocean. In chronically polluted and eutrophicated sea areas the dominant hydrobiont species are replaced by other forms adapted to certain chemical compounds. These forms of hydrobionts are widely used for the purposes of biological indication of the marine environment. Investigations over the last decade have shown a wide spread in contaminated areas and biotopes of the World Ocean of taxonomic groups of marine organisms whose fermentative system had adapted to polycyclic aromatic hydrocarbons and polychlorinated biphenyl. Such indicatory microorganisms are in particular discovered in the Sea of Azov, the Baltic and the Black Seas and in the near-surface biotope of the Pacific and the Atlantic Oceans. Of interest is the fact that in comparatively clean ocean areas, in particular in the Pacific Ocean, the indicatory microflora is poorly developed; its distribution is patchy. Dangerous effects of ecological and hygienic character are related with the accumulation of chemical compounds in marine organisms. Thus, the mean values of coefficients of accumulation of various pollutants by plankton organisms are as follows [8]: - up to 4,0 x 105 for Pb; - 3.4x 103 for Hg; - 2.1x10 4 forCd; 4.0 x 104 for PCB and - 5.0 x 103 for benz(a)pyrene. -

-

-

-

-

-

-

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13

5. The Concept of the Assimilative Capacity of the World Ocean The predicted continuation of the existing tendencies in marine pollution calls for a limitation of pollutant release to the World Ocean and regulation of their discharge, i.e. ecological regulation of the marine environment. Such a system should be based on knowledge of the ocean ecological resources and an understanding of physical, biological and chemical processes defining the activity of the natural 'self-purification' and 'plasticity' of marine ecosystems. The problems of regulation and limitation of pollutant discharge in coastal regions were described earlier (for example, in papers by Prof. Edward Goldberg [19] only taking into account the dispersal and transfer of pollutants in the ocean. However, the significant role played by the biotic component in the destruction and elimination of chemical substances is an inalienable property of the functioning of a normal ecosystem in the marine environment (as distinct from the air). Any significant redevelopments in the structural and functional characteristics of marine biocenoses are accompanied by changes of the biogeochemical function of the latter [28], and reflect a more general phenomenon, namely - the circulation of substances and energy in the marine ecosystem. Hence, in the regulation of the anthropogenic impact, due consideration should he given to the combination of processes of geophysical transport and chemical and biological destruction of toxicants. In connection with the above, the concept of the assimilative capacity of the World Ocean is of paramount importance. The assimilative capacity of the marine ecosystem Ami with regard to the given pollutant i (or a sum of pollutants), and for the m-th ecosystem, is the maximum dynamic capacity of the amount of pollutants (related to the whole of the zone or a volume unit of the marine ecosystem) that could be accumulated, destroyed, transformed (through biological and chemical modifications) and eliminated via sedimentation, diffusion or any other kind of transport beyond the boundaries of the volume of the ecosystem not disturbing its normal functioning. The assemblage of a large number of natural phenomena, due to which the 'self-purification' of the marine environment occurs, may be reduced to a few most important processes. These are: hydrodynamic transport, microbiological oxidation, biological transformation, biochemical oxidation, chemical and physical modifications, sedimentation of abiogenous particles and biosedimentation. Concentration of the pollutant C i in the aquatic environment, by analogy with the air, is, in general form, a composite function of the above mentioned characteristics (in vectorial form):

Ci(R, to)=F[g(R); OR; fOR; [2ij; Vij; Ki; ~t,i]

(1)

where g(R) is the amount of the substance released by a point source of pollution; on is the velocity of ordered transport (current velocity and settling by gravity); fOr is the coefficient of turbulent diffusion; #ij and vU are coefficients characterizing the rate of physical and chemical transformation of the i-th substance into the j-th one,

14

YU. A. IZRAEL AND A.V. TSYBAN

respectively; 2 i is the coefficient characterizing the rate of microbiological degradation of the i-th substance; ~ci is the coefficient which characterizes the rate of pollutant accumulation by suspended substances; to is the averaging time for the determination and regulation of substance concentration. The aquatic environment differs from that of the air in the fact that, for the air, ~r and 2i are almost equal to zero. In the practical assessment of the various processes of natural self-purification, they may be reduced to a limited number, since microbiological and biochemical oxidations are closely related, and biological transformation by plankton and benthic organisms is second in scale and results to the processes of microbiological oxidation of organic substances. Even chemical modifications of organic matter are less significant than microbiological transformation, taking into account the low water temperature (4--5 ~ in the depths of the World Ocean. Finally, abiogenous particle sedimentation accounts for 10070 [10] of the total flux of suspended particles leaving the euphoric zone and settling on the ocean floor. Thus, three basic processes determining the assimilative capacity can be isolated, i.e. hydrodynamic processes (At,. co), microbiological oxidation of organic pollutants (Az) and biosedimentation (Ax, t,), thus:

Ami=Ao, co+Az +A,c ' t,.

(2)

The determination of the hydrodynamic transfer of the pollutants in the region under investigation is a component required for balance estimates; and it is given due consideration in the study of the assimilative capacity of marine ecosystems. Thus, for example, 176 tons of Hg, 314 tons of Cd, 2074 tons of Pb are transported by water masses from the Baltic to the North Sea every year. At the same time, about 18 tons of Hg, 53 tons of Cd and 44 tons of Pb are transported from the North Sea to the Baltic [8]. The destruction, detoxication and elimination of pollutants from marine ecosystems occur in the process of the microbiological oxidation of organic pollutants as well as due to the settling of suspended organic matter of biogenous origin or sedimentation of terrigenous materials. A considerable portion of the latter is modified by zooplankton organisms from the finest particles into large aggregates in the process of biofiltration. Marine microorganisms are widespread in the World Ocean from the Arctic to the Antarctic, from the thin surface layer down to the deep sea, including the thick layer of bottom deposits. Each millimeter of sea water contains from a thousand up to several million cells of bacteria (Table II). Quantitative assessment of the processes of the microbiological oxidation of organic pollutants is necessary to evaluate the assimilative capacity of ecosystems, and can be obtained in realization of the programme of integrated global ocean monitoring. In this connection, of interest are the results of microbiological investigations carried out by experts of the Natural Environment and Climate Monitoring Laboratory in various regions of the World Ocean, as well as certain generali-

ECOLOGY AND PROBLEMSOF WORLD OCEAN INTEGRATEDGLOBAL MONITORING zations characterizing the rate of the

global

15

and regional processes of micro-

b i o l o g i c a l o x i d a t i o n o f oil a n d p o l y c y c l i c a r o m a t i c h y d r o c a r b o n s at t h e o c e a n - a i r interface.

TABLE II Microflora numbers, biomass, production and indicator groups of organisms (most probable numbers MPN) in the 0-100 m layer of the World Ocean -

Oceans

Total Bacteria biomass bacteria number mg C 104 t C (103 m -3 cells ml)

Bacteria mass production

The Atlantic Ocean b

36-1172 (313) a

1-31 (8)

1-33 (9)

4-340 (19)

The Indian Ocean r

45-810 (340)

1-21 (9)

1-16 (7)

The Pacific Ocean d

5-5000 (700)

0.1-131 (18)

The World 5-5000 Ocean (500) (different zones)

0.1-131 (12)

" b r d

Bacteria MPN, cells mlSaprophyte

Hydro- BP carbon oxidizing oxidizing

17-1313 (72)

0-105 ( 102)

0-104

0.1-45 (5)

0.2-124 (13)

1 0 - 1 0 5 0-104 (102)

0.2-235 (33)

2-1696 (18)

15-11120 (120)

0-104 (102)

0-103

0-103

0.2-235 (25)

0.1-1696 (15)

0.2-11120 (70)

0-105 (102)

0-104

0-103

mg C m -3 106 t C (day) (year)

0-103

Mean values. Total bacteria number, bacteria biomass production are estimated according to [10], [11]. Bacteria biomass production is estimated according to [5], [22]. Total bacteria number, bacteria biomass porduction are estimated according to [12], [26], [27].

TABLE III Primary production and destruction of organic matter in the O-lO0 m layer in various regions of the World Ocean [3] Oceans

Surface area (106 km 2)

Volume (104 km 3)

Primary organic Organic matter matter destruction production (109 t C yr-~) (109t Cyr-~)

The World Ocean

361

1338

5-43 (22) a

22--44 (30)

The Pacific Ocean

180

707

2-17 (8)

8-17 (12)

The Atlantic Ocean

106

347

1-12 (7)

7-15 (11)

The Indian Ocean

75

285

2-13 (6)

6-11 (7)

Mean values.

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YU. A. IZRAEL AND A.V. TSYBAN

During in situ experiments in the Bering Sea it was found, using isotope methods, that microorganisms can destroy about 2 ~tg 1-1 of paraffin hydrocarbon octadecan per day; the corresponding figure for the Japan Sea is 5 lig 1-~. In model in situ experiments followed by the chemical analysis, marine organisms were shown to be able to destroy, in various regions of the World Ocean, from 1 to 5.5 lig 1-1 of benz(a)pyrene (for 10 days). It is calculated that bacterioneuston of the World Ocean, populating its near-surface microbiotope, oxidizes about 1.6 mln tons of petroleum hydrocarbons per year. This makes up approximately 25~ of the total amount of oil entering the ocean environment due to anthropogenic activity (Table III). Bacterioneuston of the World Ocean is able to destroy in the order of 400 tons of polycylic aromatic hydrocarbon benz(a)pyrene per year, which accounts for 12o7o of the total amount of benz(a)pyrene entering the World Ocean (Table IV).

TABLE IV Petroleum hydrocarbons (PH) and their microbial destruction in the surface microlayer (1 cm) in various regions of the ocean Oceans

Area 106 km 2

PH content in surface microlayer

Most probable number (MPN) of hydrocarbonoxidizing microorganisms

mg m -2

In surface microlayer

In mg m -2 water a day column

mln t a year

mln t

Potential activity a of PH microbial destruction in surface microlayer

The World Ocean

361

0-5.0 (0.29) (0.8) b

0-106

0-104 ( l . 2 x 1 0 -2)

(1.58)

ThePacific Ocean

180

0-5.0 (0.8)

(0.14)

0-103 0-103 (1.2x10 -2)

(0.79)

The Atlantic Ocean

106

0-1.5 (0.3)

(0.03)

0-106

0-104 (7.2x10 -3)

(0.23)

75

0-5.0 (1.3)

(0.10)

0-106

0-104 ( l . 4 x l 0 -2)

(0.41)

TheIndian Ocean

PH input to the World Ocean mln t yr-l

Percent of microbial destruction of PH input to the World Ocean

6.7

24

" The rate of petroleum consumption (model experiment data) is 1.2 x 101~ mg h r - ~ per cell at the temperature of 10~ ~ [14]. The estimates are based on the mean values of 3.0 x 103~ hr -1. b Means are given in parentheses.

Meanwhile, a lot of molecular-stable compounds (for example, aromatic and chlorinated hydrocarbons) are only partly destroyed by microorganisms. Microbiological processes are considerably less active at the low temperature of Arctic regions and in deep sea.

ECOLOGYAND PROBLEMSOFWORLDOCEANINTEGRATEDGLOBALMONITORING

17

Marine organisms accumulate (Table V), destroy, transform pollutants and transfer them to various biotopes determining the distribution of chemical toxicants in the marine environment.

TABLE V Benz(a)pyrene (BP) content and microbial destruction in the surface Oceans

Area BP content in water

Most Potential activity of BP probable microbial destruction in numbers the oceans of BP oxidizing microflora

(104 ( g l -~) km z)

( g m -2) (cells ml -~)

g m2day -1

g t mZyr - l yr

The World Ocean

361

0-1.2 (0.021) a

0-12 (0.21)

0-103

3.15 x 103 1.15

415

The Pacific Ocean

180

0-0.8 (0.018)

0-8 (0.18)

0-103

2.7 x 103

0.99

178

The Atlantic Ocean

106

0-1.2 (0.024)

0-12 (0.24)

0-103

3.6x 10 -3 1.31

138

BP input to the World Ocean

Microbial destruction of BP input to the World Ocean

t a y r -~ 3.5 x 103

ll.8

a Means are given in parentheses. Potentials of BP microbial destruction are estimated under the assumptions as follows. (1) BP destruction is uniform over the World Ocean. (2) It has a constant rate, i.e. independent of bacteria numbers, water temperature, season, etc. (3) The rate is proportionally (linearly) dependent on water BP concentration. (4) As in situ experiments show, 15 % of the initial BP concentration is destructed for 10 days. 1 cm layer destroys 1.5 % of BP d a y - ~.

The brilliant idea about the role played by marine organisms in the extraction of chemical elements out of sea water, their removal from the water column and settling on the ocean floor, was first suggested by the famous Soviet scientist V.I. Vernadsky, who wrote: "In the history of all chemical elements two kinds of processes are significant in the regions of life accumulation, namely: the passage of the given chemical elements through a living substance and their elimination, going out of the living substance" (1960) [1]. Primary products of living substances extract chemical compounds directly out of the marine environment while consumers do that by sorption and in the process of feeding. As a result of these processes, chemical elements, including pollutants, are accumulated in the biota, migrate multiply along the food chain of marine organisms and after the die-off of hydrobionts either return to the sea water or leave the photic layer of the ocean through biogenous sedimentation and sink to the ocean floor. Here they are enclosed in deposits on the bottom and are involved anew in biochemical

18

YU. A. IZRAEL AND A . V . TSYBAN

cycles with active participation of ocean floor animals. Transport of chemical compounds into the deeper layers of floor deposits and their removal into water masses occur due to the continuous activity of digging animals in the process of biological roiling. In some regions of the ocean, hydrological factors are also responsible for the enrichment of sea water with chemical elements from floor deposits. This macroscale process of bioextraction, bioaccumulation and biosedimentation of pollutants that is now under thorough investigation (papers by Drs S. Fowler, D. Lal, S. Tsunogai, G. Polikarpov, and others), occurs more intensively in active ocean areas and presents a continuously operating mechanism performing the geophysical and biological 'self-purification' of the ocean ecosystems. It may be suggested that the results of the evaluation of modern release and biosedimentation of certain of the most dangerous pollutants (toxic metals) (Tables VI and VII) demonstrate the macroscale processes of World Ocean pollution. The quantitative characteristics of biogenous transformation can be obtained as part of the regular investigations of marine ecosystems, i.e. as one of the results from the implementation of the programme of integrated global ocean monitoring.

T A B L E VI

Pollutant concentration in suspended organic matter (g k g - 1 dry weight) at different depths in various regions of the World Ocean Depth

Region

Pollutant Pb

Cd

Hg

1.3 x 104

5.2 x 10 3

100 m

off-shore area (shelf)

1.10 x 104

open sea

8.00 x 103

3.4 x 103

4.0 x 102

400 m

open sea

1.42 x 104

4.3 x 103

5.4 x 102

T A B L E VII

Biosedimentation of organic carbon and some heavy metals from the surface (0-100 m) layer of the World Ocean (t yr-') Process

Region

Substance Organic carbon

Outside input

The World Ocean

Biosedimentation

Off-shore areas (shelf) Open sea The World Ocean

1.7 x 109 7.2 x 109 8.9 x 109

Pb

Cd

Hg

3 • 10 54x10 6

1.5 x 1023 . 4 x 104

7 x 1031.1 x 104

6.05 x 104 1.84 x 105 2.445 x 10 5

7.15 x 104 7.82 x 104 1.497 x 105

2.86 x 104 9.20 x 102 3.78 x 104

E C O L O G Y A N D PROBLEMS OF W O R L D O C E A N I N T E G R A T E D GLOBAL M O N I T O R I N G

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Removal through biosedimentation was evaluated on the basis of experimental data and theoretical concepts and suggest that about 50~ of synthesized organic matter is eliminated from the ocean euphotic zone and only 5-20070 of the total amount of particles depositing from the zone of photosynthesis (or 2-10070 of the primary production) gets to the bottom. The rest of the 80-95070 organic matter removed out of the photic layer is destroyed in the process of microbiological and chemical oxidation. Heavy metals settling out of the photic zone are accumulated on suspended particles and either get to the bottom or return into the water in the process of the destruction of biogenous aggregates and are involved anew in biogeochemical cycles. Considering data presented in Table VII, it becomes clear that the amounts of metals coming into the photic layer (0-100 m) and removed though biosedimentation are approximately equal. In some cases, however, the biosedimentation flux proved to be greater than the input, as was the case with Cd. The observed difference in the amounts of fluxes seems to be compensated for by the hydrological transport of metals in dissolved form from the subsurface layer of the ocean (10(0-400 m) to its surface waters. In spite of the fact that the open waters of the World Ocean are large in volume (as compared with the shelf zones), the amounts of Hg and Cd eliminated from 100-meter layer there is only 2 or 3 times less than those eliminated from the shelf surface layer. It is indicative of the considerable content of toxic metal in the shelf zones of the ocean. The data presented in Table VII make it possible to judge the intensity of the biogenous circulation of pollutants under study in the biologically active ocean layer. Of particular interest is the evaluation of the flux of metals with biogenous suspension from the 0-400 m layer (Table VII). Since, at the depth of 400 m, hydrodynamic transport is negligible compared with the velocity of sedimentation flux, the processes of biosedimentation determine in the main the removal of metals from this ocean layer. Notwithstanding possible errors in the quantitative assessment related to the whole of the World Ocean in its shelf and off-shore waters, the data presented in Table VIII make it possible to draw the conclusion that the total amount of lead and mercury eliminated in the process of biosedimentation from the active layer of the ocean is considerably less (3-40 times) than the mass of lead and mercury entering the ocean from anthropogenic and natural sources. The above difference is even more marked if the external load is compared with the velocity of deposition of heavy metals in the floor sediments (Table VII). These facts demonstrate the trends of Hg and Pb accumulation in the components of marine ecosystems. This conclusion is fully in conformity with earlier estimates (Table I) of anthropogenic components of Pb, Hg, and Cd (92, 70, and 50070, respectively) [29]. Further increase in World Ocean pollution by lead and Hg can Pb very soon to critical concentrations of these toxicants in water (Table VIII) and marine biota, and cause disturbances in the functioning of the biotic component closely related with the biosedimental purification of the euphotic ocean layer.

20

YU. A. IZRAEL AND A.V. TSYBAN T A B L E VIII

Input and removal of some chemical elements (at the depth o f 400 m) and rate of their deposition in bottom sediments (t yr -1) [6, 9, 15, 17, 25]

Process

Substance (element)

Outside input Biosedimentation at 400 m Deposition in b o t t o m sediments

Pb

Cd

Hg

3 x 105--4 • 106 8.52 • 104 1.42 • 104

1.5 x 103-3.4 • 104 2.58 • 104 4.30 • 103

7 x 103-1.1 • 10.4 3.24 • 103 5.40 x 102

6. Forecast of the State of the World Ocean by the Year 2000

The balances of quite a number of chemical elements and compounds contained in the World Ocean have been calculated. The basic sources of pollutants entering the ocean and the ways of eliminating them are well known, as well as the basic components of the processes of natural purification of the marine environment. The description of the dynamics of chemical toxicants in the components of marine ecosystems and the assessment of the ecological effects of the impact of pollutants are further steps to be taken in these investigations. The realization of such an approach implies the solution of the following problems: (1) Forecast of the increase in the velocity of pollutant flux to the marine environment. (2) Description of the 'self-purifying' ability of an ecosystem (assessment of microbiological and chemical oxidation, biosedimental deposition, and determination of hydrodynamic removal of pollutants out of an ecosystem). (3) Determination of critical concentrations of pollutants most dangerous to the given ecosystem. (4) Forecast of the ecological effects of the antrhopogenic impact. Analysis of modern data (Table VIII) on the global pollution of the World Ocean and its effect on the formation of organic matter shows that the mean concentration of toxicants widespread at the present time is by 1-3 orders less than their critical concentrations, those causing the 50~ decrease of the primary production of phytoplankton. Existing forecasts characterizing changes in the global output of the pollutants under study show that by the year 2000 the corresponding values will have doubled as compared with the current level. For example, global emmissions of mercury and cadmium are mainly caused by combustion of organic fuel. The amount of organic fuel consumed by the year 2000 will have doubled or trebled, and by 2025 a 4- or 5-fold increase is expected. This suggests that the concentration of metals in sea water may also increase equally (taking into account the relaxation time) and attain the following figures:

ECOLOGY AND PROBLEMS OF WORLD OCEAN INTEGRATED GLOBAL MONITORING

21

0.25 of Hg, and 0.5 Bg 1-1 (on average) of Cd. In areas with higher levels, concentration can be 2.5 and 5 Bg l-1, respectively, and exceed critical values for a number of algae forms. Provided that the assumptions made were correct, the concentrations of pollutants under investigation are expected to have doubled by the year 2000 compared with current levels. It is obvious that the maximum concentrations of Hg, PCB and oil expected in the year 2000 are within the range of variations of critical concentrations. In such a situation, the maximum decrease in primary production that may be foreseen is equal to 25-30% for individual pollutants in the World Ocean, especially under the impact of Hg, PCB and oil (Table VIII). In Table VIII it is of interest that the maximum concentrations of some toxicants in various regions of the World Ocean are at present approaching the critical values which might be associated with atmospheric deposition of pollutants. 7. Condufion

The contamination processes of the World Ocean are in the main of a regional character. The danger of oil pollution of the ocean is of a global scale; and it is expected to grow due to the intensification of off-shore industries. The serious consequences of oil pollution of the World Ocean are connected with the accumulation of PAH, molecular-stable substances possessing carcinogenic and mutagenic properties in components of marine ecosystems. The increase of the content of chlororganic, stable high-molecular toxic compounds in the open waters of the World Ocean is alarming. The influx of such chemical toxicants as lead and mercury to the World Ocean at present exceeds their elimination from the water masses; and this results in the accumulation of these metals in marine organisms and in the bottom sediments of the ocean. Of particular danger is the accumulation of pollutants in enclosed and semi-enclosed basins, on the active surfaces of the ocean, and in the zones of the ocean-air interaction where, as is well known, the most active geophysical, chemical and biological processes occur. The increase of pollutant concentration in sea water and its accumulation in marine organisms cause a decrease in the velocity of organic matter production, and disturbances in the structure of marine biocenoses undoubtedly affect and will affect the state of the ecosystem as a whole and thus the biological resources of the World Ocean. In connection with the predicted continuation of the existing trends of ocean pollution and its potential increase, the organization of integrated global ocean monitoring seems to be an urgent problem of prime importance. The problems of a scientific basis for integrated global ocean monitoring belong to the most important scientific concepts of the modern ecology of the ocean as treated in the present paper.

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YU. A. IZRAELAND A.V. TSYBAN

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[27] Tsyban, A. V.: 1975, 'Bacterioneuston and Problem of Degradation in Surface Films of Organic Substances Released into the Sea', in Water Technol. Nos. 3/4, 792-799. [28] Tsyban, A. V.: 1980, 'Scientific Approaches to Biological Monitoring of the Baltic Sea', Repp. P.- V. Reun, Cons. Int. Explor. Mer. 179, 228-236. [29] Waldichuk, M.: 1977, Global Marine Pollution. An overview. Paris, UNESCO, 20 pp. [30] Zobell, C. E.: 1973, 'Microbial Degradation of Oil: Present Status, Problems and Perspectives. The Microbial Degradation of Oil Pollutants', Workshop held at Georgia State Univ., Atlanta, December 1972, G. Adheem and S. Meyers (eds.), pp. 3-17.