Polychlorinated biphenyls (PCBs) in sediments of the southern Baltic Sea — trends and fate

The Science of the Total Environment 280 Ž2001. 1᎐15

Polychlorinated biphenyls ž PCBs/ in sediments of the southern Baltic Sea ᎏ trends and fate Joanna Konat, Grazyna ˙ KowalewskaU Institute of Oceanology, Polish Academy of Sciences, ul. Powstancow ´ ´ Warszawy 55, 81-712 Sopot, Poland Received 11 December 2000; accepted 7 February 2001

Abstract Polychlorinated biphenyls ŽPCBs. have been determined in recent w0᎐1Ž2., 1Ž2. ᎐5 and 5᎐10 cm deep layersx sediments from different sites of the southern Baltic Sea, including the Szczecin Lagoon, collected from May 1996 to October 1999, i.e. before and after the great flood in Poland of JulyrAugust 1997. The PCB distribution has been correlated with location and hydrological conditions as well as with organic carbon, algal pigments and their derivatives in the sediments. The sum of PCB Žseven congeners. was equal to ; 1᎐149 ngrg dry wt., on average this was rather low Žup to 40 ngrg.. There was a decreasing trend in PCBs concentrations in the bottom sediments of the southern Baltic in 1996 but considerable amounts were still accumulated there. The flood of 1997 caused a distinct increase of PCB concentration level in the sediments, which again showed a decreasing trend in the next few years. This illustrates that at present the main source of PCBs for the southern Baltic are not a direct consequence of human activity, but from floods and heavy rains washing these compounds from land to the sea. Algae and algal detritus play an important role in the transport and distribution of PCBs in the southern Baltic. High correlation of PCBs with chlorophyll a derivatives ᎏ products of zooplankton grazing ᎏ indicates that PCBs are ingested by zooplankton with phytoplankton and then exuded with fecal pellets. PCBs bound to algal detritus or to fecal pellets in the water column are transferred to sediments, there they may be trapped either in a bonded and unchanged form or resuspended, remobilized andror dechlorinated, depending on their properties and environmental conditions. 䊚 2001 Elsevier Science B.V. All rights reserved. Keywords: PCBs; Marine sediments; Algal pigments; Baltic Sea; Flood

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Corresponding author.

0048-9697r01r$ - see front matter 䊚 2001 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 8 - 9 6 9 7 Ž 0 1 . 0 0 7 8 5 - 9

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J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

1. Introduction Although the commercial production of PCBs in many countries of the world has ceased, their concentration trends in the environment are not so clearly determined. Reasons for this is their stability, permanent input to the environment as by-products in processes of production of other chemicals or during combustion of chlorine-containing wastes, from vehicle exhaust emissions and also in relation to various analytical problems. All the above mentioned processes result in mixtures of a large number of PCB congeners in different proportions, even though not all the theoretically possible isomers are formed. Depending on chemical structure PCBs have different physico-chemical and toxicological properties. The congener pattern of samples from different environments is influenced by both original composition of pollutants and sources of pollution, but also by varied physico-chemical properties of PCBs like solubility in water, resistance to transformation by microorganisms, etc. Different PCB congeners have been determined in different studies ŽTable 1.; often the data are not comparable. In earlier papers only the sum of PCB congeners was determined with an Aroclor standard. In recent papers, ‘standard’ Ž‘monitoring’. congeners have been used, e.g. PCB nos. 28, 52, 101, 118, 138, 153 and 180 are selected as the most abundant in the environment and covering a wide degree of chlorination ŽWells, 1993.. Because of the multiplicity of parameters controlling PCB geochemistry in the sea, together with analytical problems, PCB data are the most highly diversified and difficult to interpret. Some authors consider that algae and algal detritus may play an important role in the geochemistry of PCBs in the sea. Although the PCB content of marine macroalgae is substantial and variable depending upon the stage of decomposition Že.g. Picer, 2000., a possible phytoplankton influence on PCB marine geochemistry has only been suspected ŽKo and Baker, 1995; Schulz-Bull et al., 1995.. Eutrophication is a basic problem of the Baltic, hence it is highly probable that living and decomposed algae might have a decisive influence

upon the geochemistry of PCBs, which had been observed for PAHs ŽKowalewska, 1999.. In the Baltic PCBs were determined first in animal tissues Žfish, molluscs, birds. ŽHELCOM 17B, 35B, 64B. and some of these values were alarmingly high ŽFalandysz, 1999.. There are only few data available for PCB concentrations in water ŽHELCOM 17B, 64B; Schulz-Bull et al., 1995. and sediments of the Baltic Sea also have not been intensively studied ŽHELCOM 17B; Perttila and Haahti, 1986; van den Bavel et al., 1996. although PCBs in sediments are closely related to PCB content in bottom-feeding fish ŽBrown et al., 1998.. Only recently the western and German coasts of the southern Baltic have been monitored. Data for sediments of the Polish southern Baltic zone are scarce ŽSapota, 1995, 1996, 1997 ᎏ Table 1. and indicate very low PCB concentrations. In this work the distribution of seven PCBs containing from three to seven chlorine atoms have been determined in recent sediments of different areas of the southern Baltic Sea. The PCB levels were correlated with location and hydrological conditions as well as with organic carbon, algal pigments and their derivatives to follow possible sources and routes of transport of PCBs in the environment.

2. Materials and methods 2.1. Sediment samples Sediment samples were collected during cruises of R.V. ‘Oceania’, R.V. ‘Professor Albrecht Penck’ Žst. 9, 38. and boat expeditions of the Biological Oceanography Department of Szczecin University to the Szczecin Lagoon from May 1996 to October 1999. The samples were collected with a core sampler and a box corer Žst. 9, 38.. After collection the 0᎐1, 1᎐5, and 5᎐10 cm deep layers Žin Odra Estuary 0᎐2, 2᎐5 and 5᎐10 cm, in 1997. were separated from each core and immediately frozen at y20⬚C. Location of the sampling stations is presented in Fig. 1. The stations have been selected in such

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

way as to cover a wide variety of environments. They were located in the Gulf of Gdansk: ´ near the coast ᎏ at mouth of the Vistula River Žst.

ZN2.; the largest Polish river discharging to the Baltic Sea, near Gdynia harbor Žst. PGd.; near the tip of Hel Peninsula, at a site remote from

Table 1 Concentrations of PCBs in surface sediments of various marine environments ᎏ literature data Area Žno. of PCBs. Baltic Gulf of Bothnia Ž12. northern southern Bothnian Bay Baltic Proper Ž12. western Ž23. Ž22 stations. Arkona Basin Ž23. Ž4 stations. Oder River Estuarine system Ž23. Ž5 stations. Greifswald Boden Ž23. Ž6 stations. Meklemburg-Vorpommen Ž23. Ž26 stations. Gulf of Gdansk ´ Ž11 stations. Gulf of Gdansk ´ Ž13. Ž5 stations. Vistula Lagoon Ž6 stations. North Sea Humber Plume Ž12. Scheldt Estuary Ž13. Mediterranean Tunisian coast coast of Alicante Ž10. Aroclors., Ž6 stations. Open sea Ž1975᎐1990. Southwestern ŽClophen A40. coast of France Ž20. Ž3 stations. coast of France coast n Greece Italian coast Adriatic Venice Gulf ŽAroclor. Venice Lagoon ŽLido port. coastal open sea Atlantic Ocean Dominican coast Ž21. Ž14 stations, sand.

3

ÝPCBs Žngrg dry wt..

Sediment layer Žcm.

Reference

0.9᎐1.5 4.1᎐6.5 1.1᎐3.5rg C up to 11.0 - 0.13᎐11.4

᎐ ᎐ ᎐ ᎐ 0᎐3

van den Bavel et al., 1996 van den Bavel et al., 1996 Broman et al., 1994 Nylund et al., 1992 Dannenberger et al., 1997

2.1᎐5.4

0᎐3

Dannenberger et al., 1997

- 0.13᎐26.3

0᎐3

Dannenberger et al., 1997

2.1᎐6.9

0᎐3

Dannenberger et al., 1997

- 0.13᎐214.4

0᎐2

Dannenberger and Lertz, 1996

0.1᎐3.94 Žparticular PCBs. 1᎐9.5 0.1᎐0.99

0᎐3

Sapota, 1995

0᎐10 Žeach 1 cm.

Sapota, 1996 Sapota, 1997

2.92᎐19.7 Žfr - 63 ␮m. 10᎐200

0᎐10 0᎐85

Klamer and Fomsgaard, 1993 van Zoest and van Eck, 1993

0.5 0.06᎐2.9

᎐ 0᎐2

0.8᎐33 av. 79 Ž27.3᎐212. 29᎐181

᎐ ᎐ ᎐

Tolosa et al., 1997 Prats et al., 1992 Tolosa et al., 1997 Dachs et al., 1996

av. 85 Ž0.2᎐15 850. av. 155 Ž0.6᎐775. av. 102 Ž0.6᎐3200.

0.5᎐1 0.5᎐1 0.5᎐1

Picer, 2000 Picer, 2000 Picer, 2000

0.5᎐9.69 av. 38 Ž1᎐185. av. 181 Ž6᎐2203. av. 24 ŽND᎐332.

0᎐5 ᎐ ᎐ ᎐

Donazzolo et al., 1983 Donazzolo et al., 1983 Picer, 2000 Picer, 2000

0.46᎐41.9

᎐

Sbriz et al., 1998

Pierard et al., 1996 ´

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

4 Table 1 Ž Continued. Area Žno. of PCBs.

ÝPCBs Žngrg dry wt..

Sediment layer Žcm.

Reference

Arctic Ocean Chukchi Sea Ž1 sample.

0.14

᎐

Iwata et al., 1994

2.0

᎐

Iwata et al., 1994

0.13

᎐

Iwata et al., 1994

0.24 ; 10᎐1000 ŽAlaska-Columbia River Estuary-nrLos Angeles.

᎐ ᎐

Iwata et al., 1994 Brown et al., 1998

5᎐9.75 Žwet wt..

᎐

Connell et al., 1998

Pacific Ocean Gulf of Alaska Ž1 sample. Bering Sea Ž1 sample. Bristol Bay Coast of USA Ž50 stations, 1984᎐1990.

South China Sea Hong Kong Ž60 stations. in the typhoon shelter China rivers Ž14.a Ž12 major rivers. Canadian Lakesb Ž90. a b

Up to 169 Žwet wt.. Ž; 350 ng dry wt.. 10᎐22 Žfr - 63 ␮m.

Connell et al., 1998 0᎐5

Qi et al., 1999

2.4᎐39

; 0᎐1 cm

Muir et al., 1996

Riverine sediments. Lake sediments.

industry, where strong and changeable currents occur Žst. P110d.; stations P110, P116 Žlocated along the Vistula waters main spreading way in the Gulf of Gdansk ´ Žst. ZN2, P110, P116, G-2., and in the two deepest sites of the Polish Baltic zone, i.e. in the Gdansk ´ Deep Žst. G-2, water depth ; 110 m. and in the Bornholm Deep Žst. P5, water depth ; 100 m., the basin of the two largest Polish rivers. The first one is the direct sink for the particulate matter carried by the Vistula River, the second is the final Žeastern . trap of particulates carried by the Odra River, which first settled in the Szczecin Lagoon and then washed out to sea. The other group of stations were those located before Žst. R.O.. and in the Szczecin Lagoon: along the shipping channel Žst. K ᎏ influenced by municipal and industrial sewage from Szczecin town; L ᎏ in the mixing zone of the sea, and fresh water; M ᎏ under influence of sewage from ´ Swinoujscie, ´ Mie ˛dzyzdroje and Wolin., on both sides of it Žst. 15, 18. and in Wicko Lake Žst. J.W. ᎏ on one of

the river branches joining the lagoon with the sea. and in Pomeranian Bay: near the mouth of the ´ Swina River Žst. 38. ᎏ the main junction of the Szczecin Lagoon with the sea and on the western route of settling particulate matter carried by the Odra River into the sea Žst. 9.. Deep sediments and at P116, P110, K, L, and 9 were of a very high percentage of fine grains Žclays. and rich in organic carbon ŽG 5%., at PGd, R.O., M, 15, 18 were silts and at ZN2, P110d, 38, J.W. were sandy sediments Ž Corg - 2%.. Samples were collected before and after the flood in summer 1997. Heavy rains in the southern part of Poland resulted in a rapid rise in the river water flow, this was especially dangerous in the catchment area of the Odra, which overflowed its banks in many places covering large land areas Žover 500 000 ha. and numerous towns and villages with water. Between 21 July and 20 August five ŽVistula. to six ŽOdra. times higher quantities of water were carried by the rivers than in the relevant period of 1996, this was 50% and

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

5

Fig. 1. Location of sampling stations.

70% higher than the long-term maximum discharges for the Vistula and Odra, respectively wfor comparison the mean annual water flow of the Vistula and Odra to the Baltic in 1996 was 34.1 and 18.6 km3ryear ŽCyberski, 1992., respectivelyx. This phenomenon was accompanied by a drastic decrease of oxygen content in the river water, carrying simultaneously large quantities of organic matter and different pollutants ŽTrzosinska ´ Ⲑ ysiak-Pastuszak, 1998.. For example, in less and L than 2 months the Odra has carried the nutrient equivalent of 6᎐8 months discharge in 1996. The quality of the riverine water at the end of the flood was again comparable with the state before the flood ŽNiemirycz, 1998.. 2.2. Analysis of PCBs, pigments and their deri¨ ati¨ es and organic carbon PCBs were isolated from the studied samples using a procedure elaborated earlier ŽKowalewska and Konat, 1998.. A frozen sediment sample Žapprox. 5᎐20 g. was allowed to thaw and extracted five times with 20-ml portions of ace-

tonitrile ŽSigma, HPLC-grade. by sonication. Next, the combined acetonitrile fractions were transferred to benzene ŽSigma, HPLC-grade. in the following system: acetonitrile᎐benzene᎐water 10:1:10 Žby vol... The benzene layer was separated and solvent was evaporated under vacuum. The residue was dissolved in acetonitrile Ž3 q 1 ml.. The raw extract was purified by TLC wMerckKieselgel 60, acetonerhexane 20:35 Žvrv., applicator CAMAG-Linomat IVx. Gel at R f s 0.8 was scratched out from the plate and extracted with acetonitrile. The PCB extract was purified on the RP-18 micro-column ŽLichrolut, Merck., next on the micro-column with copper powder ŽMerck. and finally on the Florisil micro-column ŽRoth.. The detailed pigment extraction procedure has been described earlier ŽKowalewska, 1997.. The procedures of HPLC pigment determination have been described previously ŽKowalewska, 1993, 1995, 1997.. The following pigments were determined: chlorophyll a, b and c Žchl a, b, c ., phaeophytin a Žpheo a., pyrophaeophytin a Žpyropheo., phaeophorbides a Žphrbs., steryl chlorins ŽÝ steryl., ␤-carotene Ž␤-car.. Organic carbon was determined by the wet

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J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

chromic acid titration method ŽGaudette et al., 1974..

3. Results 3.1. PCB concentrations The sum of concentration levels of seven PCBs in the studied sediments is presented in Fig. 2. Before the flood of 1997 the concentration did not exceed 40 ngrg Ždry wt.. with an exception for the 1᎐5 cm layer of the station in the Deep of Gdansk ´ ŽG-2.. where it reached up to 150 ngrg and at station P116 Žup to 90 ngrg.. At station P110 also the 1᎐5 cm layer Ž; 34 ngrg. was twice as rich in PCBs as the two adjacent layers. The lowest concentrations in the Gulf of Gdansk ´ were

determined for P110d station Ž2᎐5 ngrg.. In the Szczecin Lagoon the sum of PCBs was higher Ž; 55 ngrg. only in the 0᎐1 cm layer at station L before the flood. The lowest value for that region was at the ´ Swina mouth Ž5᎐12 ngrg. Žst. 38.; at station M the values were also not higher than 20 ngrg. Already 1 month after the flood of 1997 and even 2 years after, the PCB content was higher by 1.5᎐3.7 times in the 0᎐1 cm layer, depending on location and time of sample collection. Generally, before the flood, PCBs 28 and 52 were the most abundant congeners in the 0᎐1 cm layer. The next most abundant in this layer was PCB 101. Other PCBs were more equally distributed and occurred in lower concentrations. In the 2᎐10 cm layer PCBs 28 and 52 were also the most abundant congeners, although in lower proportion. The other congeners were more uni-

Fig. 2. Sum of PCBs Žseven congeners. in recent sediments of the Baltic Sea, 1996᎐1999; at each station in 0᎐1, 1᎐5, 5᎐10 cm layer in Odra Estuary in 1997 ᎏ in 0᎐2, 2᎐5, 5᎐10 cm layer.

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

formly distributed at different stations than in the 0᎐1 cm layer. Sediments in the Deeps and at station 9 contained the highest proportion of PCB 28 and also of 52 and 101. In the Szczecin Lagoon along the shipping channel ŽK, L, M. before the flood ᎏ 101 and also 28 and 52, 2 years after the flood ᎏ 101, 52, 28. After the flood there was an increase of PCB 28 content in the Deeps and this congener was absent in sediments from all stations in the Szczecin Lagoon except for those along the shipping channel, where it was most abundant at station L. After the flood, the proportion of higher chlorinated congeners increased in all stations with an exception for the Deeps. Correlation coefficients of particulate PCBs with sum of PCBs is presented in Fig. 3. There were small differences between the correlation coefficients but generally one may say that the best correlation was with PCB 28, next with 118 ᎏ the congener most toxic to biota, and the lowest with 180. Except for the Szczecin Lagoon after the

7

flood where correlation with PCBs 28 and 52 was the lowest, the highest correlation was with PCB 101, and the next highest with PCB 153. 3.2. Correlation with organic carbon and pigments Table 2 also contains results for organic carbon. The highest organic carbon content was at stations K, and L and the next highest was in the Deeps. The correlation of PCBs and organic carbon as well as with pigments in sediments is presented in Table 3. Correlation of sum of PCBs with chlorins a Žchlorophyll a and its derivatives. was lower than that with organic carbon in the 0᎐1 cm surface layer, approximately 5 years old, while assuming an average rate of formation of sediments in the southern Baltic of 1᎐3 mmryear ŽSzczepanska and Uscinowicz, 1994., and in the ´ ´ coastal sediments. In the Deeps and in the Szczecin Lagoon, before the flood, the correlation with organic carbon was lower than that with

Fig. 3. Correlation coefficients of particular PCBs with sum of PCBs.

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J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

pigments. After the flood, in the Szczecin Lagoon, correlation coefficients with both chlorins and organic carbon were similar and very high

Ž; 0.95., distinctly higher than those for samples collected before the flood. For all the samples, the poorest correlations were with PCB 28; with

Table 2 Concentration of PCBs in recent Baltic sediments Žngrg dry wt.. 1996᎐1999 PCB 28 R.O. X99 0᎐1 cm 1᎐5 cm 5᎐10 cm K VIII96 0᎐1 cm 1᎐5 cm 5᎐10 cm K X96 0᎐1 cm 1᎐5 cm 5᎐10 cm K X97 0᎐2 cm 2᎐5 cm 5᎐10 cm K X99 0᎐1 cm 1᎐5 cm 5᎐10 cm L VIII96 0᎐1 cm 1᎐5 cm 5᎐10 cm L X96 0᎐1 cm 1᎐5 cm 5᎐10 cm L X97 0᎐2 cm 2᎐5 cm 5᎐10 cm L X99 0᎐1 cm 1᎐5 cm 5᎐10 cm M VIII96 0᎐1 cm 1᎐5 cm 5᎐10 cm M X96 0᎐1 cm 1᎐5 cm 5᎐10 cm M X97 0᎐2 cm 2᎐5 cm 5᎐10 cm M X99 0᎐1 cm 1᎐5 cm 5᎐10 cm 18 X99 0᎐1 cm 1᎐5 cm 5᎐10 cm 15 X99 0᎐1 cm 1᎐5 cm 5᎐10 cm J.W. X99 0᎐1 cm 1᎐5 cm 5᎐10 cm

F 0.18 F 0.18 0.83 3.79 9.25 5.06 2.96 2.65 2.6 5.44 11.4 18.51 6.3 5.36 2.67 14.53 5.27 9.19 1.78 2.79 4.07 14.01 16.49 11.63 7.5 9.52 7.14 3.15 1.99 2.78 1.96 0.97 1.04 10.23 4.61 4.88 3.59 7.7 3.7 F 0.18 F 0.18 F 0.18 F 0.18 F 0.18 F 0.18 F 0.18 0.37 F 0.18

PCB 52 0.89 2.1 3.51 3.13 6.58 3.90 3.01 3.26 2.77 ᎐ ᎐ ᎐ 6.36 6.98 3.89 8.67 5.51 7.95 2.49 3.42 4.24 3.73 5.11 3.55 9.01 9.6 9.5 3.26 2.40 2.51 2.57 1.35 1.62 2.45 ᎐ 3.07 4.33 7.36 4.26 3.79 4 4.28 0.4 0.65 0.7 0.31 0.33 0.37

PCB 101 6.3 4.81 4.22 5.76 8.54 4.86 5.71 5 5.39 8.73 11.06 16.53 12.56 10.14 4.28 18.33 9.03 8.71 4.39 6.27 5.39 10.81 11.56 6.32 13.12 10.00 11.4 5.54 3.28 2.41 3.73 1.53 2.58 7.32 5.75 5.62 5.53 7.58 4.14 7.94 6.34 5.17 3.06 1.7 1.1 0.29 0.29 0.4

PCB 118 1.29 0.99 1.49 1.71 2.05 0.90 0.85 1.07 1.34 3.05 3.03 4.40 2.66 1.49 1.15 2.32 2.81 2.68 1 0.75 1.07 3.59 3.83 2.17 2.07 1.77 1.96 0.85 0.62 0.45 0.45 0.38 0.87 2.37 2.69 2.25 1.16 1.05 0.94 1.1 1.36 1.16 0.75 0.38 0.28 0.02 0.03 0.06

PCB 153 4.39 2.96 2.86 2.87 1.97 1.23 2.05 1.38 1.7 5.36 5.57 7.31 5.5 2.72 2.15 5.46 3.82 3.58 1.47 1.77 1.15 5.13 6.53 3.39 4.63 5.26 5.67 1.00 0.90 0.49 1.37 0.52 0.98 3.28 3.03 2.32 2.93 2.03 1.96 2.7 2.74 1.92 2.02 1.05 0.61 0.14 0.16 0.13

PCB 138 5.07 3.14 2.94 2.16 1.87 1.08 1.3 1.11 1.13 6.07 6 6.47 5.36 2.05 1.55 3.33 3.37 3.87 0.7 0.95 0.96 5.15 5.49 3.94 3.91 4.44 4.64 0.79 0.49 0.27 1 0.45 0.89 2.82 2.95 2.58 2.43 1.84 1.88 2.09 1.96 1.3 1.78 0.7 0.41 F 0.06 F 0.06 F 0.06

PCB 180 4.03 2.53 2.75 2.41 1.60 0.83 1.64 0.86 0.94 5.16 3.66 4.95 4.05 1.72 1.48 2.35 2.69 1.65 0.7 1.06 0.7 4.47 5.21 3.32 3.27 3.54 3.55 1.01 0.50 0.34 0.85 0.28 0.59 2.41 2.66 1.82 1.75 1.7 1.43 2.11 2.01 1.52 2.11 0.96 0.62 0.1 0.09 0.09

Corg 4.95 4.24 6.5 6.27 7.32 6.2 7.14 8.24 8.17 7.4 7.54 7.43 6.03 6.17 2.75 6.56 7.58 3.82 6.15 6.75 7.9 7.66 6.47 6.22 7.66 7.37 7.63 4.9 2.97 3.62 3.2 2 3.46 3.87 4.21 4.05 3.68 3.76 2.73 5.62 4.98 3.26 4.21 3.33 3.5 0.12 0.07 0.17

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

9

Table 2 Ž Continued.

38 V97 0᎐1 cm 1᎐5 cm 5᎐10 cm 38 X97 0᎐2 cm 2᎐5 cm 5᎐10 cm 38 X99 0᎐1 cm 1᎐5 cm 5᎐10 cm 9 VII97 0᎐2 cm 2᎐5 cm 5᎐10 cm 9 IX97 0᎐2 cm 2᎐5 cm 5᎐10 cm P5 V96 0᎐1 cm 1᎐5 cm 5᎐10 cm P5 IX98 0᎐1 cm 1᎐5 cm 5᎐10 cm G2 V96 0᎐1 cm 1᎐5 cm 5᎐10 cm G2 IX98 0᎐1 cm 1᎐5 cm 5᎐10 cm P116 V96 0᎐1 cm 1᎐5 cm 5᎐10 cm P110 V96 0᎐1 cm 1᎐5 cm 5᎐10 cm P110d V96 0᎐1 cm 1᎐5 cm PGd V96 0᎐1 cm 1᎐5 cm 5᎐10 cm ZN-2 X97 0᎐1 cm 1᎐5 cm 5᎐10 cm

PCB 28

PCB 52

PCB 101

PCB 118

PCB 153

2.04 1.25 2.72 3.16 0.87 2.35 0.37 0.61 0.64 8.3 2.97 1.49 18.69 1.7 9.96 10.74 12.37 13.81 17.14 28.84 20.09 4.98 42.74 2.49 44.95 56.2 31.25 23.63 24.51 27.08 0.51 8.2 4.05 0.52 0.72 5.96 8.96 8.3 5.28 5.02 4.76

1.35 1.06 1.43 2.83 ᎐ 1.41 0.54 0.83 0.71 8.1 ᎐ ᎐ 6.17 ᎐ 5.93 10.97 10.19 12.69 ᎐ 9.82 9.34 10.75 27.01 5.32 13.99 22.85 5.6 28.54 16.17 18.08 3.27 6.78 4.53 0.46 0.86 6.47 6.71 5.49 3.64 4.38 3.69

1.31 0.94 2.54 2.88 1.13 2.49 0.81 1.02 0.76 6.15 3.77 3.03 9.14 4.76 4.67 7.78 5.62 4.87 17.13 11.03 12.94 6.31 19.58 2.61 19.17 28.74 12.78 12.92 16.72 25.26 4.15 6.79 1.62 0.4 1.01 3.1 1.93 1.38 1.26 1.97 1.57

0.43 0.32 1.03 1.01 0.36 1 0.24 0.1 0.09 2.33 1.41 1.08 2.76 1.54 1.44 0.8 2.11 2.37 4.98 5.64 4.58 2.13 16.19 3.32 7.88 11.15 4.62 5.8 5.69 6.98 1.91 5.25 1.38 0.15 0.35 1.23 1.23 0.78 0.54 1.58 1.64

1.06 0.66 1.6 1.86 0.94 2.03 0.42 0.44 0.46 2.91 2.06 1.45 5.69 3.45 2.81 2.35 2.73 3.27 7.12 10.14 10.99 3.45 13.01 2.41 8.53 12.6 5.94 4.94 5.79 4.42 1.86 2.55 1.96 0.26 0.53 1.51 1.61 1.09 0.68 0.98 1.09

other congeners they were equalized, but slightly higher for PCB 101. For pigments the highest correlation showed pyrophaeophytin-a and steryl chlorins, the lowest chlorophyll c. The Deeps gave distinctly different results where no correlation with the majority of pigments and with organic carbon was observed, while a comparatively high correlation was with

PCB 138 0.78 0.56 1.65 1.62 1.1 2.09 0.17 0.38 0.29 2.92 1.86 1.31 5.34 2.76 2.39 2.54 2.77 3.5 6.15 5.32 5.23 3.61 9.96 2.42 7.08 8.38 5.64 5.17 5.1 5.06 1.81 3.18 2.77 0.15 0.45 1.38 2.35 1.38 0.48 0.69 0.61

PCB 180 0.91 0.54 1.16 1.17 0.74 1.29 0.26 0.28 0.31 3.12 2.93 2.04 4.56 2.54 2.01 0.92 2.17 0.57 8.04 5.15 4.8 1.17 8.73 1.38 11.93 8.55 6.66 1.19 3.3 2.77 0.86 0.65 0.66 0.1 0.29 0.75 0.91 0.64 0.31 0.59 0.57

Corg 0.45 0.85 0.75 1.77 0.62 0.86 0.57 0.41 0.36 5.26 4.78 5.04 5.11 5.05 4.66 4.82 4.73 4.93 5.37 4.56 4.62 7.1 6.48 6.1 6.92 5.34 5.02 6.95 6.83 5.61 5.52 5.19 3.35 0.27 0.3 3.43 3.1 2.79 0.57 1.25 1.63

steryl chlorins and with chlorophyll c. The correlation with chlorophyll b was highest near the coast and in the Szczecin Lagoon before the flood. In the 0᎐1 cm layer and in the Szczecin Lagoon after the flood, in the last two cases with the exception for PCB 28 and 52; ␤-carotene correlated best with PCBs in coastal sediments, in the 0᎐1 cm layer Žwith exception of PCBs 28 and

10

Table 3 Correlation coefficient wln C PC B Žpmol. vs. ln Cpigment Žnmol., ln Corg Ž%.x Pyropheo a

Phrbs

Ýsteryl

Chl b

Chls c

␤-car

0᎐1 r 2 cm layer (n s 30) PCB 28 0.22 UU PCB 52 0.48 UUU PCB 101 0.78 UUU PCB 118 0.7 UUU PCB 153 0.75 UUU PCB 138 0.69 UUU PCB 180 0.71 UUU ÝPCBs-7 0.66

0.23 0.54 UUU 0.74 UUU 0.65 UUU 0.67 UUU 0.63 UUU 0.56 UUU 0.63

0.39 UUU 0.61 UUU 0.88 UUU 0.8 UUU 0.85 UUU 0.81 UUU 0.81 UUU 0.79

0.34 UU 0.47 UUU 0.74 UUU 0.73 UUU 0.76 UUU 0.74 UUU 0.72 UUU 0.65

0.44 UUU 0.58 UUU 0.86 UUU 0.78 UUU 0.81 UUU 0.78 UUU 0.85 UUU 0.79

0.21 0.39 UUU 0.74 UUU 0.65 UUU 0.73 UUU 0.69 UUU 0.72 UUU 0.63

0.33 UU 0.56 UU 0.47 UU 0.47 0.35 0.35 0.16 U 0.45

0.31 UU 0.49 UUU 0.7 UUU 0.79 UUU 0.69 UUU 0.74 UUU 0.63 UUU 0.69

0.3 UUU 0.55 UUU 0.83 UUU 0.75 UUU 0.8 UUU 0.75 UUU 0.74 UUU 0.71

Deeps (n s 15) PCB 28 PCB 52 PCB 101 PCB 118 PCB 153 PCB 138 PCB 180 ÝPCBs-7

0.1 0.27 0.28 0.37 0.38 0.25 0.27 0.26

0.18 0.09 0.23 0.33 0.47 0.37 0.47 0.27

0.31 0.34 0.47 U 0.63 0.58 0.47 0.52 0.47

0.75 0.1 UUU 0.91 UUU 0.72 UUU 0.87 UUU 0.83 UUU 0.83 UUU 0.79

0.44 0.41 UUU 0.62 0.56 UUU 0.63 0.49 0.58 0.56

0.71 UUU 0.85 UUU 0.82 0.35 U 0.61 UU 0.68 0.25 UUU 0.75

0.35 0.27 0.51 0.48 0.56 0.45 0.54 0.47

0.22 0.25 0.4 0.46 0.51 0.39 0.44 0.37

0.3 0.44 UU 0.56 0.49 0.45 U 0.54 UU 0.58 0.43

0.57 UUU 0.72 UUU 0.85 UUU 0.7 UUU 0.72 UUU 0.83 UUU 0.82 UUU 0.73

0.5 0.47 UU 0.6 0.52 UU 0.64 UU 0.61 UU 0.68 U 0.58

0.71 UUU 0.77 UUU 0.82 UU 0.7 UUU 0.77 UUU 0.73 UUU 0.74 UUU 0.8

0.23 0.27 0.44 0.42 0.5 0.33 0.46 0.37

Coastal (n s 23) UU PCB 28 0.6 UUU PCB 52 0.72 UU PCB 101 0.59 UUU PCB 118 0.65 U PCB 153 0.51 UUU PCB 138 0.52 PCB 180 0.47 UUU ÝPCBs-7 0.67

UUU

UUU

0.72 UUU 0.82 UU 0.62 UUU 0.83 UUU 0.64 U 0.53 U 0.5 UUU 0.76

0.65 UUU 0.82 UUU 0.84 UUU 0.84 UUU 0.77 UUU 0.75 UUU 0.78 UUU 0.79

Szczecin Lagoon before flood (n s 18) UU PCB 28 0.52 0.64 UU PCB 52 0.52 0.65 UU UUU PCB 101 0.7 0.82 UU UU PCB 118 0.62 0.63 UU UUU PCB 153 0.65 0.79 UUU PCB 138 0.51 0.71 U UUU PCB 180 0.57 0.8 UU UUU ÝPCBs-7 0.61 0.75

0.7 UUU 0.71 UUU 0.84 UUU 0.75 UUU 0.83 UUU 0.75 UUU 0.83 UUU 0.8

UU

UUU

UUU

UUU

UUU

0.65 UUU 0.68 UUU 0.67 UUU 0.69 UUU 0.72 UUU 0.66 UUU 0.65 UUU 0.73

UU

0.64 UU 0.65 UUU 0.83 UU 0.66 UUU 0.78 UU 0.67 UUU 0.81 UUU 0.75

UUU

UU

0.61 UUU 0.66 0.32 U 0.51 0.36 0.3 0.21 UU 0.55

y0.16 y0.22 0.15 0.03 0.22 0.09 0.24 y0.01

UUU

Ýchlns a

UUU

0.74 UUU 0.84 UUU 0.7 UUU 0.84 UUU 0.73 UUU 0.62 UUU 0.61 UUU 0.81

0.64 UUU 0.79 UUU 0.72 UUU 0.8 UUU 0.66 UUU 0.64 UUU 0.65 UUU 0.75

0.3 0.31 0.26 0.49 0.14 0.16 0.1 0.29

0.67 UU 0.67 UUU 0.83 UU 0.69 UUU 0.82 UUU 0.73 UUU 0.81 UUU 0.78

UU

Corg 0.42 0.68UUU 0.92UUU 0.85UUU 0.87UUU 0.87UUU 0.78UUU 0.83UUU

y 0.04 0.42 0.14 0.33 y 0.03 0.27 0.02 0.14

0.71UUU 0.91UUU 0.86UUU 0.83UUU 0.8UUU 0.82UUU 0.83UUU 0.83UUU

0.51 0.53 0.67UU 0.6UU 0.55U 0.48 0.62UU 0.6UU

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

Pheo a

Chl a

Chl a

Pheo a

Szczecin Lagoon after flood (n s 30) U PCB 28 0.37 0.49 UUU UUU PCB 52 0.6 0.69 UUU UUU PCB 101 0.83 0.88 UUU UUU PCB 118 0.79 0.85 UUU UUU PCB 153 0.81 0.86 UUU UUU PCB 138 0.81 0.9 UUU UUU PCB 180 0.82 0.9 UUU UUU ÝPCBs-7 0.78 0.86 U

PG 0.01; PG 0.001; UUU Ps 0.001. UU

Pyropheo a UU

0.54 UUU 0.78 UUU 0.95 UUU 0.96 UUU 0.96 UUU 0.96 UUU 0.96 UUU 0.93

Phrbs UU

0.53 UUU 0.79 UUU 0.95 UUU 0.93 UUU 0.95 UUU 0.95 UUU 0.95 UUU 0.93

Ýsteryl UU

0.53 UUU 0.77 UUU 0.92 UUU 0.93 UUU 0.95 UUU 0.93 UUU 0.93 UUU 0.92

Chl b

Chls c

␤-car

Ýchlns a

0.41 0.36 UUU 0.77 UUU 0.75 UUU 0.84 UUU 0.81 UUU 0.83 UUU 0.73

0.12 y0.06 0.25 0.21 0.16 0.26 0.25 0.21

0.42 UUU 0.73 UUU 0.9 UUU 0.92 UUU 0.96 UUU 0.89 UUU 0.9 UUU 0.87

0.5 UUU 0.74 UUU 0.94 UUU 0.92 UUU 0.92 UUU 0.94 UUU 0.94 UUU 0.91

U

Corg 0.43U 0.72UUU 0.91UUU 0.93UUU 0.98UUU 0.93UUU 0.95UUU 0.89UUU

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

Table 3 Ž Continued.

11

12

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

52. similarly as chlorophyll a, and in the Szczecin Lagoon after the flood was even better than chlorophyll a.

4. Discussion Concentrations of PCBs in the southern Baltic sediments places this environment among the less polluted in the world ŽTable 1.. Accepting the classification of Donazzolo et al. Ž1983. for the Gulf of Venice Ž- 20᎐low, 20 - average - 80, high ) 80 ngrg. this is an area of rather low pollution. The highest content of PCBs was observed not in the vicinity of the most probable sources of pollution, but in areas of intensive sedimentation. These are the zones where mixing of river and marine waters occurred, where flocculation usually occurs, such as at stations P110, P116 in the Gulf of Gdansk ´ and station L in the Szczecin Lagoon and in the sinks of particulate matter, i.e. in the Gdansk ´ Deep ᎏ the sink for particulates carried by the Vistula and in the Szczecin Lagoon ᎏ the first trap and also the final traps ᎏ on the west ᎏ station 9 and the east ᎏ the Bornholm Deep ŽP5. ᎏ for particulate matter transported by the Odra to the sea. The Gdansk ´ Deep sediments at a depth of 5᎐10 cm were less rich in PCBs than those from the Bornholm Deep. It is probable that at the time of formation of this layer Žapprox. 20᎐50 years ago. ŽSzczepanska and Uscinowicz, 1994. the Deep of ´ ´ Gdansk was slightly less polluted by PCBs than ´ the Bornholm Deep and more comparable to sediments in the vicinity of Gdynia harbor. Judging from changes in PCB concentration with depth in sediments collected in 1996, the PCBs trend was decreasing before the flood, which is in agreement with available data for the Gulf of Gdansk ´ ŽSapota, 1995, 1996.. The flood caused a distinct increase in PCB concentration due to washing out from land and riverbeds and subsequent transfer of large amounts of PCBs by rivers to the sea. This is confirmed by changes in the congener pattern after the flood which became richer in heavier PCBs in the Szczecin Lagoon and richer in PCB 28 in the Deeps. In the time period of 1᎐2 years after the flood the PCB

concentration in the 0᎐10 cm layer was still higher than before the flood Žst. G-2, P1., but the 0᎐1 cm layer was lower than in deeper layers, similarly as in 1996. On the basis of the collected data it seems evident that the anthropogenic introduction of PCBs to the southern Baltic environment is decreasing, but also that the amount still present is considerable and decomposition of these compounds is very slow. There is not much available literature on the influence of floods on PCB levels in the sea. Nevertheless, work concerning the Mississippi flood of 1993 ŽRostad, 1997. presents a similar situation to that in Poland although on a different scale, as transport of PCBs during the flood was up to 90 times higher than 2 years earlier. These were PCBs undergoing resuspension more than other pollutants studied in that work. This flood was turbulent enough to also resuspend deeper layers of the bottom sediments. It was also observed that the lower chlorinated PCBs were firstly washed out and the heavier chlorinated PCBs were enriched in the riverine bed sediments after the flood. The input of the floodwaters of the Mississippi River caused increased biomass of phytoplankton in the Gulf of Mexico, especially of diatoms and blue-green algae. In the Baltic sediments a distinct increase of pigments was observed after the 1997 flood ŽKowalewska and Dobrowolska, unpublished results., which resulted from very intensive algal Ⲑ ysiak-Pastuszak, 1998.. blooms ŽTrzosinska and L ´ Observed correlations with pigments and organic carbon ᎏ higher in the coastal samples than in those from the Deeps were distinctly the highest and almost ideal in samples collected after the flood. This was contrary to samples collected before the flood, and indicates a decisive influence of algae upon transport and distribution of PCBs in the southern Baltic Sea. Simultaneously, a higher correlation of PCBs with pyrophaeophytin a, steryl chlorins and phaeophorbides Žchlorophyll a derivatives known as products of zooplankton grazing. is observed ŽWelschmeyer and Lorentzen, 1985; Harradine et al., 1996.. This suggests that PCBs are ingested from the water column with phytoplankton algae or detritus and exuded with

J. Konat, G. Kowalewska r The Science of the Total En¨ ironment 280 (2001) 1᎐15

fecal pellets, and then transferred to sediments. However, chlorophylls are less resistant to light and oxygen than their derivatives ŽKowalewska and Dobrowolska, unpublished results .. Therefore, it is possible that the clearly higher correlation with derivatives than with the parent pigments is caused by higher stabilities of the derivatives. Also, differences in correlation coefficients with chlorophyll a and ␤-carotene Žwhich occur together almost in all algal species. may be explained by higher sensitivity of ␤-carotene to physico-chemical factors like light or oxygen ŽKowalewska and Dobrowolska, unpublished results.. In this work the possibility of direct sorption of PCBs from the water column by algae, i.e. most probably by phyroplankton and detritus derived from them is confirmed by higher levels in the Deeps than in the coastal samples, a correlation with chlorophyll c, and higher correlation with chlorophyll b for coastal samples and samples from the Szczecin Lagoon. The first relation presumably results from higher abundance of diatoms in open than in coastal waters, and chlorophyll c is a marker pigment for this group of algae ŽKowalewska et al., 1996.. Green algae and remnants of higher plants where chlorophyll b occurs are more abundant in the coastal zone ŽKowalewska et al., 1996.. The higher content of less chlorinated congeners 28 and 52 in the sediments of the Polish coastal zone was observed previously ŽSapota, 1995, 1996.. Correlation of particular PCBs in all the samples studied with sum of PCBs was linear and high Ž r G 0.75᎐0.97, Fig. 3., which implies a common source for all of them. However, an occurrence of PCB 28 is evidently different from that of other congeners, and most reasonably seems that its better solubility in water andror decomposition of higher chlorinated congeners by, e.g. microbial attack ŽBrownawell and Farrington, 1986. are responsible for the observed PCB 28 distribution. Such a conclusion is confirmed by a very poor correlation of PCB 28 with sum of PCBs in fresh sediments Ž0᎐1 cm, Szczecin Lagoon after the flood. and high correlation in old sediments ŽSzczecin Lagoon before the flood, Deeps..

13

5. Conclusions In conclusion, PCBs occur in sediments of the southern Baltic Sea in low concentrations compared to other seas and the trends are decreasing. At present, the most important source of PCBs are floods and heavy rains increasing riverine input to the sea. Besides, these compounds are introduced into the southern Baltic mainly by riverine waters or from local points near harbors or shipping channels. In the sea PCBs are sorbed by algae, which living or degraded are ingested by zooplankton and then exuded in fecal pellets. This process is enhanced during an algal bloom. Next, PCBs both in the bonded form or with the fecal pellets are transferred to bottom sediments, which may be a sink for these pollutants or a source for adjacent water columns when resuspension or remobilization as a result of diagenesis occur, depending on particular congener properties and environmental conditions.

Acknowledgements This work was done in part under the KBN ŽPolish State Committee for Scientific Research. project No. 6 PO4E 00117. The authors would like to thank Dr Brygida Wawrzyniak-Wydrowska of the University of Szczecin for collecting the sediment samples in the Szczecin Lagoon and in the Pomeranian Bay, M.Sc ´ Swie ˛toslⲐawa Dobrowolska of the Institute of Oceanology, PAS for determination of pigments and organic carbon in samples collected in 1998 and 1999. References Bavel van den B, Naf ¨ C, Berquist PA, Broman D, Lundgren K, Papakosta O, Rolff C, Strandberg B, Zebuhr I, Zook D, Rappe C. Levels of PCBs in the aquatic environment of the Gulf of Bothnia: benthic species and sediments. Mar Pollut Bull 1996;32:210᎐218. Broman D, Naf ¨ C, Axelman J, Pettersen H. Time trend analysis of PAHs and PCBs in the Northern Baltic proper. Chemosphere 1994;29:1325᎐1331. Brown DW, McCaine BB, Horness BH, Sloan CA, Tilbury KL, Pierce SM, Burrows DG, Chan S-L, Landahl JT, Krahn

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Tolosa I, Readman JW, Fowler SW, Villeneuve JP, Dachs J, Bayona JH, Albaiges J. PCBs in the western Mediterranean. Temporal trends and mass balance assessment. Deep-Sea Res II 1997;44:929᎐950. Trzosinska A, Łysiak-Pastuszak E. In: Trzosinska A, An´ ´ drulewicz E, editors. Conclusions Žin English.. Dorazne ´ skutki powodzi 1997 roku w ´srodowisku wodnym Zatoki Gdanskiej i Zatoki Pomorskiej ŽShort-term results of the ´ flood of 1997 in the aquatic environment Žin Polish... Gdynia: MIR, 1998:72᎐76. Wells DE. Current developments in the analysis of polychlorinated biphenyls ŽPCBs. including planar and other toxic metabolites in environmental matrices. In: Barcelo D, editor. Environmental analysis techniques applications and quality assurance. Elsevier Sci Publ, 1993:113᎐148. Welschmeyer NA, Lorentzen CJ. Chlorophyll budgets: zooplankton grazing and phytoplankton growth in a temperate fjord and the Central Pacific Gyres. Limnol Oceanogr 1985;30:1᎐21. van Zoest R, van Eck GTM. Historical input and behaviour of hexachlorobenzene, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in two dated sediment cores from the Scheldt estuary, SW, Netherlands. Mar Chem 1993;44:95᎐103.