Marine Pollution Bulletin

Marine Pollution Bulletin, Vol. 12, No. 6, pp. 210-213, 1981. Printed in Great Britain.

O025-326X/81/O60210q)4 $02.00/0 Pergamon Press Ltd.

Organic Substances in the Baltic Sea M. EHRHARDT Institut fur Meereskunde, Kiel, BRD.

Introduction

In view of the potentially very large number of organic pollutants which are likely to enter the Baltic Sea via land run-off, precipitation, from ships, or as a result of past and present dumping, the number of organic substances actually measured on a scale sufficiently large for an overall assessment is rather small. These substances are:

mineral oil, chlorinated hydrocarbon pesticides, polychlorinated biphenyls.

It is recognized, of course, that these substances, especially in the case of mineral oil, consist of a multitude of individual chemical components, but this is not the point. Rather there may be many more chemically quite different organic substances with potentially harmful effects present in the Baltic Sea which are measured only occasionally, such as phthalate ester plasticizers 0Ehrhardt & Derenbach, 1980); others whose existence is known, but which are not measured in the Baltic, such as halogenated paraffins (Jernel0v et al., 1972); and still others which have not yet been detected in seawater (e.g. components of pulp mill effluents, non-halogenated hydrocarbon pesticides, degration products of contaminants).

Thus, it appears to be fairly difficult to assess the degree of pollution of the Baltic Sea by organic substances, because any estimation of the relative hazard to the ecosystem of the small number of frequently measured organic substances must be regarded as little more than an educated guess.

The question arises: Why has the attention of organic marine chemists been focused on mineral oil (hydrocarbons) and chlorinated hydrocarbons? For several reasons: the amount of material introduced into or transported across the Baltic, known toxicities, the obvious ecological impact of large scale oil contamination which, although the Baltic Sea has been spared a catastrophe so far, is an ever present threat, and the relative ease with which these substances are analysed. It is no secret that a flame ionization detector equipped gas chromatograph is an instrument as ideally suited for hydrocarbon trace analysis as a GC furnished with an electron capture detector for the detection and measurement of chlorinated hydrocarbons. However, the almost exclusive emphasis on hydrocarbons and chlorinated hydrocarbons in no way reflects an indolence on the part of the analyst, it merely accentuates the fact that marine organic trace analysis remains a formidable challenge in spite of all improvements made in the recent past. It is important to recognize that here a gap exists of unknown magnitude and significance concerning possible organic contaminants of the Baltic Sea and their ecological impact.

This gap, which is not unique to the situation in the Baltic but to some degree exists in every ocean environment, may

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be closed by a careful search for organic trace constituents of seawater. In this search, difficulties are encountered less with methods of analysis which have been developed to a fairly high degree of sophistication, e.g. computerized gas chromatography-mass spectrometry, than with the very low concentrations of organic substances in seawater, whether indigenous or man-made. Successful attempts have been made to overcome this problem (Ahnoff & Josefsson, 1974; Osterroht, 1974; Ehrhardt, 1978) which should lead to a broader understanding of marine organic chemistry in general and the degree of pollution of the Baltic in particular.

After these introductory remarks I shall now try and assess the situation in the Baltic with respect to pollution by mineral oil (fossil hydrocarbons), chlorinated hydrocarbon type pesticides, and polychlorinated biphenyls (PCBs).

Mineral Oil (Fossil Hydrocarbons) The annual input of mineral oil into the Baltic is

estimated to be 50-100000 t yr-~. Quantitative measurements of oil concentrations in water usually follow the analytical procedure described in the Guide to Operational Procedures for the IGOSS Pilot Project on Marine Pollution (Petroleum) Monitoring (UNESCO, 1976) or its supplement Manual for Monitoring of Oil and Petroleum Hydrocarbons in Marine Waters and on Beaches (UNESCO, 1977). Very briefly, the method consists of extracting seawater with a suitable organic solvent and, after a short work-up, comparing the fluorescence intensities of the extracts with those of standards of known concentrations. The pros and cons of the method regarding its specificity for mineral oils shall not be discussed here. Suffice it to say that data from at least two laboratories indicated an overwhelming contribution to the fluorescent material by fossil hydrocarbons (Bouchertall & Ehrhardt, 1979; Ahnhoff & Eklund, 1979). However, it is very important to realize that the composition of the hydrocarbon mixture present in seawater, even when its origin is crude oil, will be changed with time by environmental factors (evaporation, microbial decomposition, etc.). Although its origin may still be recognizable, its composition might differ drastically from that of crude oil.

Instead of the UV-fluorescence method, some labora- tories have used the absorption of infra-red radiation by water extracts at specific wavelengths to measure the concentration of fossil hydrocarbons in seawater, but this method suffers from two drawbacks relative to the UV- fluorescence method: it is not nearly as sensitive, the lower limit of detectability being ca. 50/2g of oil per litre of water (Carlberg, 1977), and it cannot distinguish between recent

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biogenic and fossil hydrocarbons. When filtered water samples are analysed, this last detriment may not be as severe as one might suppose, since our investigations (Ehrhardt, unpublished data) clearly show that in most cases whatever hydrocarbons are present in aqueous solution or accommodation are fossil in origin. In particulate matter (plankton, detritus, etc.), however, recent biogenic hydro- carbons are indeed found in various proportions to fossil hydrocarbons. Thus, hydrocarbon concentrations obtained with the infra-red method in unfiltered water samples tend to be biased towards unrealistically high values when there is a high particle load in the water samples. Bearing in mind this limitation of the method, it is reassuring to note that in the Baltic Proper oil concentrations in 84°70 of 275 samples were below the detection limit of the infra-red method, 13 °70 in the 50-100 tag 1 1 range and only 2% higher than this. In the Kattegat-Skagerrak area 74.4% of 125 samples were found to contain oil below the detection limit, 21.7°70 in the 50-100 tag 1-~ range and 3.9% above.

The reporting of results obtained with the UV-fluores- cence method in crude oil equivalents is based on the assumption that hydrocarbon mixtures extracted from seawater contain fluorescent aromatic hydrocarbons in roughly the same proportion as crude oils. This assumption may not always be correct. Our investigations (Bouchertall & Ehrhardt, 1979) indicate a substantial contribution to the hydrocarbon mixture in seawater by high boiling paraffins. Thus, since paraffins are not 'seen' by the UV-fluorescence method, a high paraffin content in the extracts should result in the calculation of too low oil concentrations.

Because different oil standards have been used by different laboratories (Iranian crude oil, Ekofisk crude oil), the overall agreement of results obtained with the UV- fluorescence method is surprisingly good when such a comparison could be made.

Swedish in-shore waters have been found to contain from 7 to 20/ag 1- ~ of oil above the pycnocline and 3 to 7/ag 1- below (Anon., 1974). In the open Baltic Sea concentrations range from 0.3 to 8.3 tag 1 -l with an average of 1.55/ag 1 l (Ahnoff & Johnson, 1976) and from 0.8 to 3.2/ag 1-J with an average of 1.8 tag 1-~ (Dahlmann et al., 1979). No general tendency is apparent in the data to indicate areas or depth horizons in the water column with exceptionally high con- centrations of oil. Oil concentrations in the surface film, however, ranging from 33 to 717 tag m 2 (Dahlmann et al., 1979) with an average of 215 tag m 2, tend to be distinctly higher in the Kat~egat area than elsewhere (Table 1).

With respect to biological and ecological consequences of oil contamination, few papers appear to have been published for the Baltic Sea area. A paper by Linden (1976) contains data on the toxicity of mixtures of a crude oil with dispersants (Finasol EC, Finasol OSR-2, and BP 1100-X) to Baltic herring eggs and embryos. No adverse effects were observed of concentrations below 250 tag 1 1 of the most toxic mixture.

A publication by Notini (1978) describes the effects of an oil spill on Fucus macrofauna in a small bay in the southern part of the Stockholm archipelago. After 4 years no significant evidence was found of lasting detrimental effects.

Hazard assessments of long time chronic exposure to sublethal concentrations of oil residues dissolved in natural seawater do not exist for pelagic communities, whether in the Baltic or elsewhere, largely because toxicity studies have never been made with the oil-derived material present in seawater. This material consists of crude oil components such as aliphatic, alicyclic, aromatic, and heterocyclic compounds whose relative proportions, however, differ from those in crude oil. Low boiling components, for instance, are missing, and high boiling paraffins in the vicinity of n-C2sH58 are fairly abundant. In addition,

TABLE 1

Results of pe t ro leum hydrocarbon analyses ( reproduced f rom Dah lmann etal., 1979).

Subsurface (/ag 1- l)

Station Position Surface Sampler Depth Sampler Depth ~ g m 2) (m) (m)

7 56 ° 9' N 18 ° 43' E 133 SET* 13 1.23 SET 85 1.04 BOSEX 9 5 6 ° 0 . 2 ' N 18043 ' E 117 K 13 1.07 SET 110 0.80

area 12 56 ° 9.9' N 19 ° 2.8' E 33 K 13 1.28 13 56 ° 5' N 18 ° 36.5' E 100 K 13 1.02

Average values 88 1.17 0.92 Subtracted average solvent blank 75 0.08

1 54 ° 49' N 9 ° 50' E 633 K 6 1.90 K 16 1.76 2 54 ° 43' N 10 ° 8 ' E 183 K 8 1.53 K 18 1.56 4a 54 ° 36' N 10 ° 2 7 ' E 100 K 6 1.81 K 13 1.69 5 54 ° 26' N 10 ° 4 3 ' E 117 K 16 1.92 7a 54o34.9 ' N 11 ° 13.9' E 717 K 10 2.71 K 25 3.22 8 54o26 ' N 11°27 ' E 516 K 8 1.71 K 18 1.31 9a 54 ° 15' N 11 ° 18' E 217 K 8 1.90 K 18 2.42

10 54 ° 7' N 11 ° 4' E 142 K 8 1.72 K 18 2.08 13a 54 ° 55' N 13 ° E 67 K 10 1.96 K 35 1.39 17 54 ° 40' N 15 ° 10' E 142 K 10 1.88 K 56 1.99 20 54 ° 29 'N 9 ° 57' E 342 K 10 2.49 25 54 ° 27" N 10 ° 16' E 158 K 7 1.69 K 14 2.85 28 55 ° 19.4' N 15 ° 49.9' E 67 K 10 1.95 K 80 1.56 29 55 ° N 14 ° E K 10 1.54 K 40 2.24

Subtracted average solvent blank 183 0.17

*SET = stainless steel sampler . t K - glass sampler .

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Marine Pol lu t ion Bulletin

T A B L E 2

Compar i son of results of chlor inated hydrocarbon determinat ion for the whole Baltic Sea (reproduced f rom Andrulewicz & Samp (1979) concentra t ions in ng 1-I)

Authors Study area DDT DDE DDD DDT PCBs

Anhof f & Joseffson (1974) GOta River (surface layer) . . . .

Osterroht (I 977) Baltic (HanO Bay) 0.1 - 0 . 2 0.5 - 5.2 - _

Stadler & Ziebar th (1974) Western Baltic 0.1 - 0 . 3 - 0.3 - 3.4 (surface layer)

A n d r u l e w i c z e t a l . (1977) Gdafisk Basin 0.03 - 4 . 2 2 0.03 - 3 . 0 0 0 . 0 2 - 1.1 0 . 0 8 - 6 . 8 5

Andrulewicz & Samp (I 979) G d y n i a - " B o s e x - 7 7 " - - - 1.1 - 4.7

0.3 1.2

0.3 - 5 . 0

1.1 - 5 . 9

0.1 - 10.2

1 .5 -28 .1

aromatic carbonyl compounds such as benzophenone, anthraquinone, fluorenone, a dimethyl acetophenone, and a tolylaldehyde were tentatively identified by combined gas chromatography-mass spectrometry as components of this mixture. Some of these compounds were found in surface water (Bouchertall & Ehrhardt, unpublished data), others in the anoxic deep water of the Gotland Sea (Ehrhardt, 1980). These compounds may be photo-decomposition products of fossil or pyrogenic hydrocarbons as suggested by investi- gations by Patel et al. (1979). Their effects on marine organisms are as little known as toxic concentrations.

T A B L E 3

PCBs and DDT in Baltic Sea water ( reproduced from B r a g m a n n & Luckas (1978))

Date of Sea area sampl ing

PCBs (1976) ng I - 1

p . p ' - D D T +

p . p " - DDE ng 1-1

1. LObecker Bucht 24.03. 1.6 0.6 06.08. 6.1 0.8

2. Fehmarnbel t 06.08. 138.8 2.3

3. Mecklenburg Bucht 28.01. 6. I 2.6 18.02. 2.1 0.6 07.08. 18.9 0.6

4. Kadetr inne 07.08. 11.5 0.5

5. Arkonabecken 21.02. - 0.4 26.03. 1.8 0.3 27.03. 0.7 0.3 08.08. 8.6 0.8 08.08. 7.6 0.7

6. Bornho lmsga t 08.08. 6.6 0.7

7. Bornho lmbecken 29.03. 0.9 0.2 09.08. 1.6 0.2 10.08. 3.8 0.4 10.08. 5.5 0.8

8. Gdansker Tief 07.04. 5.9 0.4 11.08. 8.1 0.4

9. S0dOstl. Got land 10.04. 0.3 0.2

10. Got tandbecken 20.02. - 0.4 12.08. 1.4 0.5 13.08. 2.7 0.2 13.08. 3.0 0.3

11. Westl . Go t l and 15.08. 2.9 0.4

12. FarOtief 08.04. 2.3 0.3 14.06. 4.0 0.4

13. Landsor t t ie f 15.08. 9.1 0.8

Concent ra t ion range 0.3 - 138.8 0.2 - 2 . 6

Mean value* 5.0 0.63

S tandard deviat ion* 5.0 0.56

Relative s tandard deviat ion* (%) 84 89

*Omit t ing PCB value of s ta t ion No. 2.

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Assuming that concentrations of this mixture are roughly measured with the UV-fluorescence method, and assuming also that its specific toxicity does not differ drastically from that of oil preparations used in toxicity studies, biota in the Baltic Sea do not seem to be acutely endangered by oil contamination. Toxicity studies which are summarized in the proceedings of an ICES workshop (McIntyre & Whittle, 1975) and in a publication by FAO (1977) indicate that toxic effects on sensitive organisms are not observed before oil concentrations reach the 100-1000/~g 1-1 concentration range. Allowing for a safety factor of ten, these concentra- tions are at least ten times higher than those observed in the Baltic Sea which nevertheless appears to be uncomfortably close to toxic levels. It cannot be overemphasized that this hazard assessment has to be regarded with extreme caution. It does not take into account the difficulties involved in transcribing laboratory results to conditions in a natural environment, nor synergistic or antagonistic effects nor the likelihood that the limited time frame of laboratory experiments does not permit the detection of effects on community structures which may first become apparent after years of exposure.

Chlorinated llydrocarbons (Pesticides and PCBs)

In contrast to the difficult quantification of mineral oil, mainly caused by its extremely complicated composition, rather straightforward and well documented methods exist for the quantitative analysis of chlorinated hydrocarbons both in seawater and in organisms. Especially the fact that higher chlorinated hydrocarbons are exclusively man-made obviates the necessity to single out toxic components from a natural or at least harmless background as in the case of fossil hydrocarbons, ttowever, because of considerable difficulties encountered with the analysis and quantification of exceedingly low concentrations of chlorinated hydrocarbons in seawater, relatively few data exist on their concentrations in the Baltic (e.g. Stadler & Ziebarth, 1976; Osterroht, 1977; Stadler, 1977).

Table 2, taken from a recent publication by Andrulewicz & Samp (1979), summarizes concentration data for different areas of the Baltic Sea.

Table 3, taken from a publication by Brtigmann & Luckas (1978), corroborates these data.

The observation of Luckas et al. (1980a,b) that ~-DDT concentrations in fish declined in recent years, but that PCB concentrations in this substrate remained nearly constant, suggests that a similar trend should manifest

Volume 12/Number 6/June 1981

itself in the water . U n f o r t u n a t e l y , the scarci ty o f da ta does

not pe rmi t the ver i f ica t ion o f this hypothesis .

A hazard assessment to the b io ta based on concen t ra -

t ions o f ch lor ina ted h y d r o c a r b o n s in the Balt ic Sea is no

less di f f icul t t han in the case o f fossil hyd roca rbons . Al l

factors con t r ibu t ing to the uncer ta in ty o f an eva lua t ion

discussed unde r tha t topic are equa l ly val id for ch lor ina ted

hydroca rbons , agg rava t ed by the fact that ch lo r ina ted

hydroca rbons , in cont ras t to h y d r o c a r b o n s , a re subject to

b iomagn i f i ca t ion . Thus , concen t r a t ions which do no t

affect p r imary p roducers m a y well exert dele ter ious

influences in h igher t roph ic levels. H o w e v e r , since toxic

effects o f ch lor ina ted h y d r o c a r b o n s are no t observed b e f o r e

concen t ra t ions reach the ~ag 1 ~ range in wate r (Bowes,

1972; Dex te r & P a v l o u , 1973; P o w e r s et al., 1975), con-

cent ra t ions o f ch lor ina ted h y d r o c a r b o n s do no t appea r

to const i tu te an acute m e n a c e to mar ine life in the Balt ic

Sea. H o w e v e r , in view o f cons tan t , i f no t increasing,

P C B concen t r a t ions a con t inued survei l lance is requi red o f

concen t ra t ions o f ch lo r ina ted h y d r o c a r b o n s in the wate r

and in organisms . In add i t ion , the con t inu ing inpu t o f

pe t ro leum h y d r o c a r b o n s and u n k n o w n quant i t ies o f

organic substances which have no t yet been recognized as

env i ronmen ta l c o n t a m i n a n t s calls for carefu l obse rva t ions

o f b io logica l p h e n o m e n a which can serve as sensit ive

indicators o f e n v i r o n m e n t a l stress. E x a m p l e s w o u l d be

changes in the s t ructure o f l i t toral a lgae communi t i e s ,

changing p l a n k t o n popu la t ions , the occur rence o f t u m o u r s

in fish, the induc t ion o f aryl hydroxylase etc. , indica tors

which cou ld on ly be h in ted at by a chemis t , and whose

p roper design and execu t ion wou ld fall unde r the

responsibi l i ty o f the m a r i n e biologists .

Ahnoff, M. & Josefsson, B. (1974). Simple apparatus for on-site con- tinuous liquid-liquid extraction of organic compounds from natural waters. Analyt. Chem., 46, 658-663.

Ahnoff, M. & Johnson, L. (1976). Quantitation and characterization of petroleum hydrocarbons in Baltic Sea water. Report on the chemistry of sea water XIX, Department of Analytical Chemistry, University of GOteborg, Sweden.

Ahnoff, M. & Eklund, G. (1979). Oil contamination of Melville Bay water after the Potomac accident in August 1977. Report on the chemistry of sea water XX, Department of Analytical Chemistry, University of GOteborg, Sweden.

Andrewlewicz, E., Samp, R., Slaczka, W. & Garbalewski, C. (1977). Chlorinated hydrocarbons in the Dansk Basin. Project EPA-USA No. PR.05.532-13.

Andrulewicz, E. & Samp, R. (1979). Chlorinated hydrocarbons in the cross-section Gdynia - "BOSEX-77" area. Paper presented at the XI Conference of Baltic Oceanographers, Rostock, GDR, 24-27 April 1978.

Anon. (1974). Analysis of sea water and sediments with emphasis on environmental contamination. Gothenburg to Uddevalla. Report on the chemistry of sea water XIV. Department of Analytical Chemistry, University of GOteborg, Sweden.

Bouchertall, F. & Ehrhardt, M. (1979). A GC-MS based preliminary interpretation of UV-fluorescence data on marine oil pollution. Paper

presented at the ad-hoc meeting of the IOC-WMO Group of Experts on the Evaluation of the Marine Pollution (Petroleum) Monitoring Pilot Project (MAPMOPP), Tokyo, 9-13 July, 1979.

Bowes, G. W. (1972). Uptake and metabolism of 2,2-bis-(p-chlorophenyl)- 1,1, l-trichloroethane (DDT) by marine phytoplankton and its effect on growth and chloroplast electron transport. Plant Physiol., 49, 172-176.

Br~gmann, L. & Luckas, B. (1978). Zum Vorkommen von polychlorierten Biphenylen und DDT-Metaboliten im Plankton und Wasser der Ostsee. Fischerei-Forschung, Wissenschaftliche Schriftreihe, 16, 31-37.

Carlberg, S. R. (1977). A five year study of the occurence of non-polar hydrocarbons (oil) in Baltic waters. Int. Explor. Mer., 171, 66-68.

Dahlmann, G., Gaul, H. & Weichart, G. (1979). Investigations of temp- erature, salinity, oxygen, pH, alkalinity and organic pollutants in the Baltic Sea during BOSEX '77. Paper presented at the 67. Statutory Meeting of the International Council for the Exploration of the Sea (ICES), Warsaw, Poland, 1-5 Oct. 1979.

Dexter, R. N. & Pavlou, S. P. (1973). Chemical inhibition of phyto- plankton growth dynamics by synthetic organic compounds. Journdes d'~tudes sur les pollution marines. 155-157.

Ehrhardt, M. (1978). An automatic sampling buoy for the accumulation of dissolved and particulate organic material from seawater. Deep Sea Res., 25, 119-126.

Ehrhardt, M. (1980). Preliminary results of a novel sampling technique for dissolved and particulate organic material in deeper water layers. Paper presented at the 12th Conference of Baltic Oceanographers, Leningrad, 14-19 April, 1980.

Ehrhardt, M. & Derenbach, J. B. (1980). Phthalate esters in the Kiel Bight. Mar. Chem., 8,339-346.

FAO (1977). Impact of Oil on the Marine Environment. Reports and Studies No. 6.

Jernel6v, A., Rosenberg, R. & Jensen, S. (1972). Biological effects and physical properties in the marine environment of aliphatic chlorinated byproducts from vinyl chloride production. WaterRes., 6, 1181-1191.

Lind6n, O. (1976). The influence of crude oil and mixtures of crude oil/dispersants on the ontogenetic development of the Baltic herring, Clupea harengus membras L. Ambio, 5, 136-140.

Luckas, B., Wetzel, H. & Rechlin, O. (1980a). Zur Kontamination von Ostseefischen mit polychlorierten Biphenylen. Nahrung, 24, in press.

Luckas, B., Wetzel, H. & Rechlin, O. (1980b). Ergebnisse der Trend- untersuchungen von Ostseefischen in Bezug auf ihren Gehalt an DDT und seinen Metaboliten. Acta hydrochim, hydrobioL, 8, in press.

Notini, M. (1978). Long term effects of an oil spill on Fucus macro- fauna in a small Baltic bay. J. Fish. Res. Board Can., 35, 145-153.

Osterroht, Ch. (1974). Development of a method for the extraction and determination of non-polar, dissolved organic substances in sea water. J. Chromatogr., 101,289-298.

Osterroht, Ch. (1977). Dissolved PCBs and chlorinated hydrocarbon insecticides in the Baltic, determined by two different sampling pro- cedures. Mar. Chem., 5, 113-121.

Patel, J. R., Griffin, G. W. & Laseter, J. C. (1979). As quoted in The Transfer of Pollutants in Two Southern Hemispheric Oceanic Systems. Proc. Workshop, Plattenburg Bay, South Africa, pp. 109-111.

Powers, C. D., Rowland, R. R., Michaels, R. F., Fisher, N. S. & Wurster, C. F. (1975). The toxicity of DDE to a marine dinoflagellate. Environ. Pollut., 9, 253-261.

Stadler, D. F. (1977). Chlorinated hydrocarbons in the seawater of the German Bight and the Western Baltic in 1975. Dt. Hydrogr. Z., 30, 189-215.

Stadler, D.'F. & Ziebarth, U. (1976). p.p'-DDT, Dieldrin and poly- chlorierte Biphenyle (PCB) im Oberfl/tchenwasser der westlichen Ostsee 1974. Dt. Hydrogr. Z., 29, 25-31.

UNESCO (1976). Guide to Operational Procedures for the IGOSS Pilot Project on Marine Pollution (Petroleum) Monitoring. Manuals and Guide No. 7.

UNESCO (1977). Manual for Monitoring of Oil and Petroleum Hydro- carbons in Marine Waters and on Beaches. Supplement to Manuals and Guide No. 7.

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