Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the White Sea, Russia

PII: S0025-326X(00)00004-7

Marine Pollution Bulletin Vol. 40, No. 10, pp. 807±818, 2000 Ó 2000 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0025-326X/00 $ - see front matter

Reports

Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the White Sea, Russia VLADIMIR M. SAVINOV à, TATIANA N. SAVINOVA à, JOLYNN CARROLL *, GENNADY G. MATISHOVà, SALVE DAHLE  and KRISTOFFER NáS§  Akvaplan-niva AS, Polar Environmental Centre, N-9296 Tromsù, Norway àMurmansk Marine Biological Institute, 17 Vladimirskaya St., Murmansk 183010, Russian Federation §Norwegian Institute of Water Research Southern Branch, Televn 3, N-4879 Grimstad, Norway The extent of environmental contamination and sources of polycyclic aromatic hydrocarbon (PAH) compounds to sediments of the White Sea are evaluated and compared with previously published results for adjacent Arctic Sea areas. Concentrations of two- to six-ring PAHs of molecular mass 128±278 including perylene and sediment characteristics are considered in this investigation. Mean RPAH concentration was 61%34 ng/g dw …n = 11† for all samples and 87%43 ng/g dw …n = 6† for pelite-rich samples (>83% pelite). These concentrations are 2±3 times lower than were previously reported for the SE Barents Sea. Concentrations of RPAH and RCPAH in the central White Sea have increased by a factor of 2-5 over preindustrial background levels based on 210 Pb age-dating of one sediment core. Using principal component analysis (PCA), two common factors explained 87.5% of the total variance for the White Sea data. Factor 1 is associated with high-temperature combustion processes and is related to emissions from a local aluminium smelter. Factor 2 is associated mainly with the introduction of petrogenic PAH compounds and perylene into Dvina Bay via the Severnaya Dvina River. A comparison of the White Sea and SE Barents Sea data indicates that similarities exist in the composition of parent PAH compounds. However, based on a comparative analysis of parent PAH ratios and relative contents of alkyl-substituted homologues, a common atmospheric source of anthropogenic pollutants can be ruled out. Further investigations are needed to determine whether sedimentary PAH signatures in areas of the Barents Sea that are in closer proximity to the White Sea are related to emissions from the aluminium smelter. Ó 2000 Elsevier Science Ltd. All rights reserved. *Corresponding author. Tel.: +47-77-75-03-14; fax: +47-77-68-0301. E-mail address: [email protected] (JL. Carroll).

Keywords: PAHs; sediment; White Sea; Barents Sea; Russian Arctic; atmospheric emissions.

Introduction The group of chemical compounds known as polycyclic aromatic hydrocarbons (PAHs) represents an important class of compounds that contributes to the overall hydrocarbon load in the Arctic environment (Robertson, 1998). PAHs are formed by (1) low to moderate temperature diagenesis of sediment organic matter to fossil fuels, (2) direct biosynthesis by bacteria, fungi, higher plants and insect pigments, and (3) high-temperature pyrolosis of organic materials. The pervasiveness and variety of processes, both natural and anthropogenic, that are responsible for generating PAH compounds make it particularly dicult to extract information on sources from environmental data. Yet information on sources is needed because of concerns over the persistence of some PAH compounds in the environment and associate high-bioaccumulation potential in aquatic organisms (Robertson, 1998; McElroy et al., 1989). A number of PAH compounds are known carcinogens (IARC, 1987). In the White Sea, municipal and industrial activities in adjacent cities produce a variety of waste products which are subsequently introduced into the marine environment by land-based discharges, runo€ and atmospheric deposition. Aluminium smelter operations in Kandalaksha City is one of the main industrial contaminant sources (MREC, 1998). Several large pulp and paper mills which operate in Arkhangelsk and Novodvinsk are additional sources (AREC, 1998; Yu®t et al., 1998). Previously, contaminant levels were monitored in the White Sea by the Regional 807

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Hydrometeorological Service of the Former Soviet Union. However, few data are available concerning the status of oil contamination (Grikurov, 1993; Melnikov et al., 1993). Furthermore, the historical data on hydrocarbons does not contain information on the content and composition of PAHs in bottom sediments. In this study, we investigate PAH levels in sediments of the White Sea. Data are provided on the composition and associate concentrations of PAHs in surface sediments. Information is extracted on primary anthropogenic sources of hydrocarbons using the statistical analysis method of principal component analysis (PCA). Historical trends in the supply of PAHs are identi®ed from the horizontal and vertical distributions of sedimentary PAHs in combination with knowledge of the sedimentation patterns. These results are then used to evaluate the role of the White Sea as a potential source of PAHs to the adjacent SE Barents Sea. North-west Russia, including the White Sea area is the most industrially developed part of the circumpolar Arctic. The region includes the highly populated areas of Murmansk Province, as well as the Republic of Karelia, Komi Republic, Arkhangelsk Province and Vologda Province. And it is reasonable to presume that these areas are contributing to background concentrations of Arctic contaminants. Arctic contamination is also originating from anthropogenic activities at midlatitude population centres in Northern Europe and the Former Soviet Union (Patton et al., 1991; Muir et al., 1988; Barrie, 1986). Large-scale atmospheric and oceanic circulation patterns and northward ¯owing rivers have been implicated as potential long-range transporters of contaminants from these areas (Barrie et al., 1992).

However, little direct evidence has been available identifying regional or long-range sources of PAHs in the Arctic. The search for con®rming evidence linking contaminant sources to sinks is particularly important in the Barents region due to the signi®cance of this region as a ®sheries resource area (Toresen, 1999). Few publications exist on PAH levels and composition in bottom sediments from adjacent areas of the White Sea (Loring et al., 1995; Yunker et al., 1996). Until now, no PAH data have been published on the White Sea. The White Sea results presented in this paper are contrasted with results from the Pechora Sea (Loring et al., 1995) and from the SE Barents Sea (Yunker et al., 1996) in order to investigate potential linkages among these areas. The White Sea The White Sea (Fig. 1) is a relatively small coastal sea with a surface area of only 90  103 km2 and a volume of 6  103 km3 . It contains three main sections: Voronka (Funnel), Gorlo (Throat) and the Basin. The Basin is comprised of three large bays: Kandalaksha, Onega and Dvina. Average and maximum depths in the sea are 67 and 350 m, respectively (Dobrovolsky and Zalogin, 1982). A sill extends across the entrance to the open sea with the sill depth increasing from 10 m near the Kola Peninsula to 50 m on the opposite shoreline (Scarlato, 1991). The combined freshwater discharge for rivers entering the White Sea is 180 km3 /yr. The largest rivers are Severnaya Dvina River (108 km3 /yr), MezenÕ River (24 km3 /yr) and Onega River (15 km3 /yr) (Mikhailov, 1997). Climatological conditions in the White Sea are similar to the high arctic, whereas the light regime and summer surface temperatures are more characteristic of the

Fig. 1 Map of the White Sea with sampling locations indicated.

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subarctic. In winter, frequent passages of Atlantic low pressure cyclones to the Barents Sea lead to predominantly south-westerly winds blowing from the continental high-pressure areas in central Russia. Precipitation frequently occurs as snow when these cyclones pass over the White Sea. At other times, north-easterly winds result in westward movements of the high-pressure systems over North-west Siberia and the Kara Sea producing clear, dry weather and low temperatures. Ice formation generally begins in November, and from February until the beginning of May the entire sea is usually covered by fast-ice or pack-ice (Byzova, 1995). In summer, predominant wind directions are from north, east and north-east resulting in low cloud cover and precipitation. Summer and autumn are generally periods of maximum precipitation; the mean annual precipitation in Arkhangelsk is 480 mm (Babkov and Golikov, 1984).

Material and Methods Field sampling procedures Surface sediment samples were collected in the White Sea onboard R/V Vsevolod Beryozkin in July±August 1994 (Fig. 1). Surface sediment samples were collected at 11 stations located in Kandalaksha, Dvina, Onega Bays, in Gorlo, and in the central part (Basin) of the White Sea (Table 1). Sediments were retrieved by a 40 kg 0.1 m2 van Veen grab. Sub-samples of the 0±1 cm layer were collected from the grab samples with a stainless steel spoon for PAH, total organic carbon (TOC), total nitrogen (TN) and grain size analysis. One sediment core was retrieved at station 32 using a Niemesto corer (5 cm inner diameter). The core was sectioned and the following depth intervals were stored for later PAH analysis: 0±1, 1±2, 2±4, 10±12 and 28±30 cm. All samples collected for PAH analysis were stored in specially cleaned glass jars and frozen at )20°C. Grain size, TOC and TN determinations Grain size distribution was determined for each sample gravimetrically after wet sieving. Sediment water content was determined after drying a sample to con-

stant weight (for 4 days at 50°C). Samples analysed for TOC content were pre-treated with HCL to remove inorganic carbon, followed by catalytic (Fe, Cu) combustion at 480°C. The content of CO2 gas formed was quanti®ed by IR detection using a LECO IR 212 carbon analyser. The TN-levels were determined according to a modi®ed Kjeldahl method. Samples were pre-digested with H2 SO4 , K2 SO4 and Se (catalyst), followed by spectrophotometric detection of the NH4 complex formed using a ChemLab autoanalyser. Polycyclic aromatic hydrocarbon analyses The procedure used for the analysis of PAHs is based on the International Oceanographic Commission (UNESCO) guidelines (IOC, 1982) with minor modi®cations. Individual sediment samples (25±110 g) were homogenized, treated with methanol and KOH, and re¯uxed for 1.5 h together with a 1.0 ml solution of seven deuterated PAHs. This solution included the following PAHs: naphthalene-d8 (CIL, DLM-365), biphenyl-d10 (CIL, DLM-494), anthracene-d10 (CIL, DLM-102), phenanthrene-d10 (CIL, DLM-371), pyrened10 (CIL, DLM-155), chrysene-d12 (CIL, DLM-261) and perylene-d12 (CIL, DLM-366). The solid fraction was removed by ®ltration and the elute containing PAHs was extracted with pentane. The extracts were puri®ed by column chromatography using Varian Bond Elute solid phase extraction cartridges containing 500 mg silica (Varian LRC, A1211-3036) and eluted with pentane and dichloromethane. The ®nal extract was analysed by capillary column gas chromatography with mass spectrometric detection (HewlettPackard MS 5971, HP 5890 Gas Chromatograph equipped with a split/splitless injector and a 25 m 0:20 mm ID HP Ultra 1 column, and HP G 1034 B software for MS ChemStation). Detection limits for naphthalene, phenanthrene, anthracene, dibenzothiophene and their alkyl homologues were of the order of 1 ng/g dry sediment. Detection limits for other PAH compounds were approximately 0.1 ng/g dry sediment. Analyses were performed at Unilab Analyse AS, Tromsù, Norway. The laboratory is accredited for hydrocarbon analyses according to the European

TABLE 1 Station locations in the White Sea, July±August 1994 and distance from the head of Kandalaksha Bay to each station. Number of station 22 23 25 26 27 28 29 30 31 32 33

Latitude (North)

Longitude (East)

Distance (Km)

Depth (m)

Location

66°29.900 66°11.110 65°12.330 64°44.150 65°19.280 64°45.900 64°51.840 65°03.460 65°07.960 65°30.420 65°54.340

34°14.850 35°06.920 35°10.970 36°04.450 36°42.380 39°15.910 39°37.010 39°46.640 38°49.930 37°52.520 39°26.710

113 164 255 319 284 413 414 407 370 310 347

292 257 37 47 135 24 15 23 106 126 85

Kandalaksha Bay Kandalaksha Bay Onega Bay Onega Bay Basin Dvina Bay Dvina Bay Dvina Bay Basin Basin Gorlo

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standards of NS-EN 45001 and ISO/IEC Guide 25. Since 1996, the laboratory has participated in the European Commission sponsored intercomparison exercise, QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe). Quality assurance and control protocols are described in the Unilab Quality Assurance Handbook (UNILAB, 1998). The handbook contains standard laboratory operating procedures, work plans and internal data auditing procedures. Laboratory quality control procedures include analyses of sample blanks, reference material and spiked samples. The reference material used for quality control was supplied by the National Research Council of Canada (HS4 reference material). Instrument stability and response is checked using NIST-solutions. 210

Pb Analyses Pb analyses were conducted at the Danish Institute for Water Quality (VKI) on one sediment core collected from Station 32. The method of analysis is described in Phei€er-Madsen and Sùrensen (1979). Brie¯y, 210 Pb was determined on sediment subsamples (0.5 g dw) after digestion with concentrated HCL and HNO3 acids. Samples were electro-deposited onto nickel discs. Sample activities of 210 Po were quanti®ed by alpha spectrometry. The following sediment depth intervals were analysed: 0±1, 1±2, 3±4, 5±6, 7±8, 10±11, 13±14, 17±18, 21±22, 29±30, 39±40 cm. 210

Statistical methods PCA was used to detect relationships among the variables quanti®ed in this study. The main applications of PCA are to reduce the number of variables and to detect structure in the relationships among variables. Principal components are formed by linear combinations of the original variables taken as orthogonal to one another. The ®rst factor accounts for the maximum amount of variance and subsequent factors explain

successively smaller quantities of the original variance. PCA was performed on log-transformed data (PAH concentrations, percent material with grain size <63 lm and distance from top of Kandalaksha Bay) using STATISTICA version 4.5, StatSoft. Cluster analysis was used to identify stations with similar PAH composition. The analysis was performed on relative contents of PAH compounds, using STATISTICA version 4.5, StatSoft.

Results Sediment characteristics Sediment samples were classi®ed as pelite (silt+clay) (<0.063 mm in diameter of grains), sand (0.063±2 mm) and gravel (>2 mm). Pelite predominated in bottom sediments collected at stations 22, 23 (Kandalaksha Bay), 27, 31, 32 (Basin) and 30 (Dvina Bay) (Table 2). Sediments containing high C/N ratios (>14) were found at stations 26 (Onega Bay) 28, 29, 30 (Dvina Bay) and 33 (Gorlo). This indicates a high-relative content of terrigenic matter probably in association with in¯ows from the Rivers Onega and Severnaya Dvina. The C/N ratios determined at other stations varied from 7.6 to 8.6; a range that is normally associated with marine sediments. Mass and linear sedimentation rates were determined for one sediment core collected at station 32 based on a linear regression of log excess 210 Pb activity against cumulative mass depth (Robbins, 1978). Sedimentation rates at this location are low (390 g mÿ2 yÿ1 and 1.6 mm yÿ1 ). Sediment ages for the upper three intervals (from the ®ve) collected for PAH analyses, are: 0±1 cm (1988± 1994), 1±2 cm (1977±1989) and 2±4 cm (1957±1978) (Table 3). Accordingly, sediments below a depth of 7 cm must have been deposited prior to 1904. Anthropogenic sources would not have directly contributed to the PAH composition of these sediments.

TABLE 2 Sediment grain size (% dw), total nitrogen (TN) and total organic carbon (TOC) content in bottom sediments. Station

22 23 25 26 27 28 29 30 31 33 32 32 32 32 32

810

Layer (cm)

0±1 0±1 0±1 0±1 0±1 0±1 0±1 0±1 0±1 0±1 0±1 1±2 2±4 10±12 28±30

Grain size composition

TN (mg/mg)

Pelite

Sand

Gravel

98.7 96.5 17.8 21.3 83.9 32.8 2.4 95.6 96.5 4.1 83.5 85.1 92.0 92.7 95.0

1.1 3.5 28.9 46.4 15.8 66.0 97.2 4.2 3.5 63.5 13.8 12.2 8.0 7.1 5.0

0.2 0.0 53.3 32.3 0.3 1.3 0.4 0.1 0.0 32.4 2.7 2.6 0.0 0.2 0.0

2.4 2.1 1.0 <0.1 1.8 <0.1 <0.1 2.6 2.0 <0.1 1.9 1.9 1.9 1.4 1.3

TOC (%)

C/N

19.3 17.2 8.1 6.0 13.6 4.2 1.6 35.6 16.3 1.6 14.9 15.8 14.6 12.1 10.7

8.0 8.2 8.1 >60 7.6 >42 >16 13.7 8.2 >16 7.8 8.3 7.7 8.6 8.2

Volume 40/Number 10/October 2000 TABLE 3 Aromatic hydrocarbons (ng/g dw) and corresponding ages of sediment layers for station 32. Compounds

0±1 cm 1988±1994

1±2 cm 1977±1989

2±4 cm 1957±1978

10±12 cm <1904

28±30 cm <1904

47 16

86 36

103 38

27 8

12 2

RPAH RCPAH

PAH concentrations Concentrations of RPAH in the White Sea bottom sediments (sum of the two- to six-ring PAHs) varied from 13 to 208 ng/g dw (Table 4). Both minimum and maximum concentrations were found in Dvina Bay at adjacent stations (stations 29 and 30, respectively). The granulometric compositions of sediments from these stations di€er. At station 29, the pelite fraction accounted for only 2.4% of sediment weight, while at station 30 pelite accounted for 95.6% of sediment weight. The maximum concentrations of naphthalenes, anthracenes/phenanthrenes, dibenzothiophenes, PAHs with molecular mass from 152 to 228, and perylene were found at station 30. Maximum concentrations of other PAHs (chrysene, benzo¯uoranthenes, benzopyrenes, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene and dibenzo [a,h]anthracene) were found at station 22 (Kandalaksha Bay).

Total concentration of potentially carcinogenic PAHs (RCPAH) (benzo[a]anthracene, benzo¯uoranthenes, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene; (IARC, 1987) varied from 3 to 48 ng/g dw, depending on the granulometric composition and station locations. The highest concentrations of RCPAH were found in pelite-rich sediments at stations 22 and 23 (Kandalaksha Bay) (Table 4). PAH composition PAH pro®les for all stations are shown in Fig. 2A. Cluster analysis indicates that stations cluster into two groups (Fig. 2B). The ®rst group (Group 1) included stations 22, 23 (Kandalaksha Bay) 25, 26 (Onega Bay), 27, 31 and 32 (Basin). The PAH pro®les have a predominance of compounds with molecular mass 252 (benzo¯uoranthenes + benzopyrenes) and 276

TABLE 4 Aromatic hydrocarbons (ng/g dw) in surface (0±1 cm) bottom sediments. Compounds

Station 22

23

25

26

27

28

29

30

31

32

33

Naphthalene C1 -Naphthalene C2 -Naphthalene C3 -Naphthalene Phenanthrene Anthracene C1 -Phenanthrene/Anthracene C2 -Phenanthrene/Anthracene C3 -Phenanthrene/Anthracene Dibenzothiophene C1 -Dibenzothiophene C2 -Dibenzothiophene C3 -Dibenzothiophene Acenaphthylene Acenaphthene Fluorene Fluoranthene Pyrene Benzo[a]anthracene Chrysene Benzo[b+k]¯uoranthene Benzo[e]pyrene Benzo[a]pyrene Perylene Benzo[ghi]perylene Indeno[1,2,3-cd]pyrene Dibenzo[a,h]anthracene

1.2 0.8 n.d. 0.9 4.8 0.8 2.0 3.1 2.4 0.3 0.6 0.8 0.7 0.4 0.4 0.6 9.5 6.4 3.4 9.0 28 4.9 3.1 4.0 27 8.5 5.0

1.4 1.0 1.9 1.1 3.7 0.7 1.7 2.7 1.9 0.3 0.5 0.7 0.5 0.4 0.2 0.5 6.5 4.5 2.3 6.5 23 4.1 2.0 4.7 20 6.6 4.6

1.3 0.7 1.7 1.2 2.0 0.4 1.1 2.1 1.3 0.1 0.4 0.4 0.7 0.3 0.3 0.4 3.6 2.0 1.2 3.4 15 1.6 1.4 0.8 12 4.5 0.4

0.6 0.3 0.8 0.4 1.5 0.3 0.8 1.4 1.6 0.2 0.3 0.5 0.5 0.1 0.2 0.3 3.4 1.8 1.2 3.4 16 1.5 1.5 1.0 12 4.1 3.7

1.2 0.6 0.9 0.7 2.6 0.5 1.0 1.9 1.3 0.2 0.3 0.4 0.3 0.3 0.2 0.4 5.4 3.2 1.7 4.8 17 2.8 1.6 1.8 15 5.1 3.4

n.d.a 0.7 1.1 0.5 1.2 0.3 1.2 2.4 2.2 0.2 0.6 0.6 0.6 0.1 0.2 0.3 2.7 1.8 0.7 2.1 5.6 0.8 0.8 5.5 4.3 1.1 0.9

n.d. 0.1 0.3 0.1 0.6 1.7 0.4 0.8 0.7 0.1 0.4 0.2 0.3 0.1 0.1 0.2 0.6 0.4 0.2 0.5 1.9 0.2 0.2 1.7 1.4 0.3 0.2

6.9 2.4 4.0 2.7 8.2 2.4 4.1 11 12 0.1 1.6 4.1 3.1 2.0 0.5 1.1 15 13 3.9 8.7 14 3.2 2.5 67 9.0 1.9 1.7

0.8 0.6 1.1 0.7 2.4 0.4 1.0 1.8 1.0 0.2 0.5 0.3 0.3 0.3 0.2 0.3 4.4 3.0 1.5 4.5 12 2.7 1.0 2.5 10 3.1 2.0

n.d. 0.1 0.6 n.d. 1.9 0.4 0.9 1.8 1.2 0.1 0.6 0.1 0.4 0.2 0.2 0.4 3.5 2.2 1.2 3.3 8.7 1.8 1.0 1.8 9.6 3.2 1.8

n.d. 0.1 0.3 n.d. 0.4 0.1 0.3 0.9 0.9 0.1 0.4 0.1 0.2 0.1 0.1 0.1 0.7 0.4 0.2 0.7 3.0 0.1 0.4 2.8 2.3 0.7 0.4

RPAH RCPAH

129 48

104 38

61 23

59 26

76 29

38 9.0

13 2.8

208 24

59 20

47 16

16 4.7

a

n.d. ± Not detected.

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(A)

(B) Fig. 2 (A) PAH concentrations (ng/g) and pro®les for the White Sea samples, which includes the sum of unsubstituted parent compounds and their alkyl-substituted homologues: naphthalene (Ns), phenanthrenes (Ps), dibenzothiophenes (Ds) and molecular mass totals for ¯uoranthene and pyrene (202); benz[a]anthracene and chrysene (228); benzo[b,k]¯uoranthene, benzo[e]pyrene, and benzo[a]pyrene (252); indeno[1,2,3-cd]pyrene and benzo[ghi]perylene(276), perylene (PER) and dibenzo[a,h]anthracene (DBA). (B) Tree-diagram of cluster analysis of PAH composition in bottom sediments.

(indeno[1,2,3-cd]pyrene + benzo[ghi]perylene). Group 2 included stations 28, 29, 30 (Dvina Bay) and 33 (Gorlo). For these stations, phenanthrenes and perylene were the predominant compounds. Perylene content, expressed 812

as a percentage of RPAH for stations 28, 29, 30 and 33 was 14.3%, 12.6%, 32.5% and 17.5%, respectively. In other samples perylene accounted for no more than 4.5% of RPAH.

Volume 40/Number 10/October 2000

Factor analyses revealed that the ®rst common factor (Factor 1) accounts for 46.6% of the total variance (Table 5). This factor has signi®cant positive loadings on compounds with molecular mass from 228 to 278 (perylene excluded), percent material <63 lm and signi®cant negative loading on distance from top of Kandalaksha Bay. Distance from top of Kandalaksha Bay correlated negatively …p < 0:05† with PAHs of hightemperature pyrolitic processes origin: benzo[b + k]¯uoranthene …r ˆ ÿ0:66†, benzo[a]pyrene …r ˆ ÿ0:60†, benzo[ghi]perylene …r ˆ ÿ0:71† and indeno[1,2,3-cd] perylene …r ˆ ÿ0:73†. Based on this composition, factor 1 is essentially the high-temperature pyrogenic factor in which the abundance and distribution of the associated compounds is controlled by the grain size distribution of bottom sediments and distance from Kandalaksha Bay. A decrease in the concentrations of PAH compounds with sample grain size also has been reported for Prince William Sound, Alaska (Boehm et al., 1998). The second common factor (Factor 2, 40.9% of total variance) has signi®cant positive loadings with petrogenic PAHs (naphthalenes, phenanthrenes, dibenzothiophenes), combustion-speci®c PAHs (acenaphtene, acenaphthylene, ¯uorene, ¯uoranthene, pyrene) and perylene. Perylene correlated …p < 0:05† with phenanthrenes/anthracenes …r ˆ 0:78† and with dibenzothiopenes …r ˆ 0:84†. Factor 2 represents a mixed petrogenic/pyrogenic (combustion) factor.

TABLE 5 Varimax normalized matrix of PAH in bottom sediments from the White Sea, 1994. Compounds

Percent of total variance 46.6 Factor 1

Naphthalenesa Phenanthrenes/anthracenesa Dibenzothiophenesa Acenaphthylene Acenaphtene Fluorene Fluoranthene Pyrene Benzo[a]anthracene Chrysene Benzo[b, k]¯uoranthene Benzo[e]pyrene Benzo[a]pyrene Perylene Benzo[ghi]perylene Indeno[1,2,3-cd]pyrene Dibenzo[a,h]anthracene Distance from top of Kandalaksha Bay Percent fractions with size <63 lm

0.742 0.770 0.897 0.811 0.789 0.941 0.963 0.812 )0.763

40.9 Factor 2 0.782 0.920 0.948 0.801 0.706 0.774 0.711 0.760

0.869

0.716

a Sum for substituted naphthalenes, phenanthrenes/anthracenes, and dibenzothiophenes with 0±3 alkyl carbons.

Discussion Sources of PAHs Exact identi®cation of PAH sources to the White Sea is not feasible due to the variety of processes contributing to the formation and preservation of PAHs in marine sediments. However, similarities in the relative content of various PAH compounds in pro®les from di€erent stations indicate where similar factors have operated in the development of the measured PAH signatures. The predominance of certain compounds also indicates particular formation processes. When assessed in conjunction with information on major pollution sources for a particular region, we can often retrospectively infer the primary factors that lead to the appearance of these compounds in the environment (Page et al., 1999; Burns et al., 1997). For the White Sea, sediment PAH pro®les separate into two distinct groups. PAH composition of Group 1, representing the largest number of stations, contains a predominance of compounds with molecular mass 252 and 276 and indicates a high-temperature pyrogenic source. A signi®cant correlation identi®ed by factor analysis with distance from Kandalaksha Bay indicates that the primary source of this PAH signature is related to an industrial source in Kandalaksha City. Although we do not know the exact composition of industrial emissions from this area, the primary industry is the operation of an aluminium smelter. Nñs and Oug (1997) have shown previously that sediments impacted by aluminium smelter discharges into Norwegian fjords contain a predominance of high-molecular mass compounds. Using PCA to interpret their pro®les, Nñs and Oug (1997) were not only able to di€erentiate between pro®les impacted by aluminium versus manganese smelter operations but also among individual receptor locations. The source-speci®c signals were discernable over considerable distances and down to concentrations 3±4 times background levels. In general, the pro®les contained a predominance of compounds with molecular mass 252 and 276. The predominance of these high-molecular mass compounds in their sediment PAH pro®les is consistent with our White Sea results. Similar to the Norwegian fjords, the observed PAH signature in White Sea sediments was coherent as far away as 310 km from the source region of the Kandalaksha area. This also indicates a direct and ecient transport mechanism from source to sedimentary sink. However, unlike the Norwegian fjords where PAHs are to a great extent discharged directly into the sea, the main source of PAHs from the Kandalaksha aluminium smelter is via atmospheric emissions. Local air currents must transport PAHs over the White Sea in a plume of gas and aerosol particles which are then deposited on the sea/ice surface by precipitation (Barrie, 1991), particle deposition (Voldner et al., 1986), and gas exchange (Bidleman and McConnell, 1995). 813

Marine Pollution Bulletin

Sediments from other areas (Group 2 stations) contain a di€erent PAH signature compared to Group 1 stations. PAH pro®les for stations adjacent to the Severnaya Dvina River mouth and in the main out¯ow channel to the Barents Sea contain high-relative contents of phenanthrenes, dibenzothiophenes and perylene. Phenanthrenes have petroleum, combustion and diagenetic origin, but the high-relative contents of the more highly alkylated homologues (Table 4) indicate a petroleum source (Steinhauer and Boehm, 1992). Dibenzothiophenes are distinct components of many crude oils (Steinhauer and Boehm, 1992). Fossil fuel pollution index (FFPI; Boehm and Farrington, 1984; Steinhauer and Boehm, 1992), is a diagnostic ratio designed to determine the approximate percentage of fossil PAHs relative to the total PAH in a sample. The FFPI is calculated as:   Ns ‡ Ps ‡ 12 …Ps ‡ C1 P† ‡ Ds  100; FFPI ˆ RPAH where Ns, Ps, and Ds are the sum of the naphthalene, phenanthrene and dibenzothiophene homologue series, respectively. These homologue series include the parent compound and the alkyl-substituted homologues. C1 P is methyl phenanthrene and RPAH is the sum of the twoto six-ring PAHs. FFPI calculated for Group 2 stations are consistently high, varying from 21% to 26%. For comparison, FFPI values, calculated for Group 1 stations are relatively low ranging from 11.0% to 19%. For Group 2, a correlation is observed between phenanthrenes versus perylene, as well as dibenzothiophenes versus perylene. This indicates a river source of petrogenic PAHs. Indeed, in 1997 more that 4000 t of oil products entered the White Sea via rivers, mainly the Severnaya Dvina River (AREC, 1998). The other predominant PAH in Group 2 samples, perylene, has both terrigenous and marine origins (Venkatesan, 1988). Perylene is sometimes found in areas where organic debris in sediments is predominantly derived from marine sources. In this case, perylene formation is attributed to bacterial degradation of organic matter in anoxic sediments. However, perylene may also be detected in marine sediments predominantly rich in terrigenous plant residues (Aizenshtat, 1973). In one nearshore area of Prince William Sound, Alaska, for example, perylene concentrations exceeding several hundred ppb are attributed to an abundant supply of organic debris in combination with a restricted circulation regime (Bence et al., 1996). The C/N ratios (>14) measured in sediment samples from Dvina Bay are much higher than typical marine values (6) as shown by Prahl et al. (1980) and indicate a terrigenous origin for this organic debris. The Severnaya Dvina River is heavily impacted by operations of the pulp and paper industries including two pulp and paper mills located near to the river mouth (Yu®t et al., 1998). The relatively high C/N ratios and correspondingly high levels of perylene detected in 814

Dvina Bay sediments are probably a response to discharges of plant debris into the river from these facilities. Accordingly, this local industrial source of plant debris is probably responsible for the observed di€erences in the PAH signatures between the Dvina Bay and other areas of the White Sea. The similarities in PAH pro®les between station 33 and stations within Dvina Bay indicate that the in¯uence of the Severnaya Dvina also extends beyond the immediate vicinity of the Bay. Thus bottom sediments containing perylene located in the main transport pathway of river out¯ow to the north-east from the White Sea, and perhaps further into the adjacent Barents Sea, may be useful as a marker for Severnaya Dvina River water. Historical levels of PAHs At station 32, sedimentation rates (390 g mÿ2 yrÿ1 and 1.6 mm yrÿ1 ) and the associate sediment ages of the individual depth intervals indicate that below 10±12 cm, sediments are older than 100 yr. Below this depth, 210 Pb geochronology cannot be used to determine ages for the sediment layers. However the PAH concentrations associated with these depths must correspond to pre-industrial times and therefore must represent background levels (Table 3). These background concentrations (RPAH ˆ 27:0 ng/g dw and RCPAH ˆ 8:2 ng/g dw) are roughly 2±5 times lower than the concentrations found in sediment intervals deposited after 1957. PAH concentrations also increased from the sediment surface (1994) to a depth of 2±4 cm (1957±1978). To explain a decrease in PAH concentrations with time, we acquired data on air discharges from non-ferrous metallurgy industries compiled by the State Committee of the Russian Federation on Statistics (Statistical Book, 1998). These data consist of annual emissions estimates for Russia but only for the time period 1991±1997. Over the 3-year time period 1991±1994, emissions have decreased from 5089 to 3502 t/yr. While we would prefer to have site-speci®c data extending to earlier years, this trend of decreasing emissions might also explain the changes observed in PAH concentrations at station 32. Comparison with the Barents and Pechora Seas Large rivers are important transporters of materials from land to marginal seas. For example, in the Beaufort Sea, the Mackenzie River has been shown to be an important contributor to sedimentary PAH signatures (Yunker and Macdonald, 1995; Yunker et al., 1993). In the SE Barents Sea (St. 182), Yunker et al. (1996) identi®ed combustion inputs to sediments and concluded that some of these inputs are likely to be of anthropogenic origin. Anthropogenic PAHs in the SE Barents Sea are possibly related to sources supplied by the Pechora River or the White Sea via the Severnaya Dvina River. Nñs and Oug (1998, 1997) have shown that particulate, combustion-derived PAHs are resistant to transformation during marine transport and that

Volume 40/Number 10/October 2000

Fig. 3 Fingerprints of PAHs (bars) and parent PAHs (black dots) for bottom sediments in the White Sea, Pechora Sea (Loring et al., 1995) and SE Barents Seas (Yunker et al., 1996; Yunker, pers. comm.). Abbreviations: C0 , C1 , C2 , C3 are unsubstituted parent compounds and their alkyl-substituted homologues of naphthalene (Ns), phenanthrene (Ps), and dibenzothiophenes (Ds), FLN ± ¯uorene, ACL ± acenaphtylene, ACN ± acenaphthene, BaP ± benzo[a]pyrene, PER ± Perylene, DBA ± dibenzo[a,h]anthracene. Parent PAH molecular mass totals are shown for anthracene (grey) and phenanthrene (black) (178), ¯uoranthene (grey) and pyrene (black) (202), benz[a]anthracene (grey) and chrysene (black) (228), benzo[b,k]¯uoranthene (grey), benzo[e]pyrene (black) and BaP (252), indeno[1,2,3-cd] pyrene (grey) and benzo[ghi]perylene (black) (276).

marine discharges of aluminium smelter operations impart unique PAH signatures to sediments. We therefore looked for similarities in PAH ®ngerprints among the di€erent regions in order to identify the presence of land-based sources of anthropogenic PAHs (Fig. 3). This comparison was only possible after acquiring ad-

ditional data and information from the main author of the Barents Sea investigation (Yunker, pers. comm.). PAH concentrations in the White Sea are 2±3 times lower than in the north-western and southeastern parts of the Barents Sea (Table 6). However, the levels in the White Sea are comparable to the levels reported for 815

Marine Pollution Bulletin TABLE 6 PAH concentrations in bottom sediments from the Barents and White Seas (ng/g dw). Area

n

Mean ‹ S.D. a

NW Barents Sea Southeast Barents Sea NE Barents Sea, coast of Novaya Zemlya Pechora Sea White Sea (all samples) White Sea (samples with predominance of pelites) a b c

b

Sources b

b

PAH

Ns

Ps

Ds

18 12 10

200  150c 230  140 97  38

170  180 46  22 34  31

180  170 57  30 62  21

87 33 16  9

Yunker et al., 1996 Yunker et al., 1996 Yunker et al., 1996

7 11 6

96  48 61  34 87  43

68  29 44 55

18  12 10  10 14  13

34 22 33

Loring et al., 1995 Present data Present data

Parent PAHs of molecular mass 178±278. Sum for naphthalene and its alkylated homologues (Ns), the same for phenanthrene/anthracene (Ps), and dibenzothiophene (Ds). Perylene excluded.

sediments from the Pechora Sea (Loring et al., 1995). The average RCPAH level in the pelite fraction of the White Sea bottom sediments (29  12 ng/g dw) is also comparable with data for the Pechora Sea (32  20 ng/g dw) (Loring et al., 1995). Based only on the predominant parent PAH compounds, similarities are observed between the SE Barents Sea and White Sea (Group 1 stations only). These compounds are the pyrogenic compounds with molecular mass 252, 276 and 202 (Fig. 3). The PAH compositions of these White Sea samples were previously identi®ed as the result of emissions from the Kandalaksha aluminium smelter and not from discharges into the Severnaya Dvina River. In the Pechora Sea, petrogenic naphthalene is among the predominant compounds in all samples. From this analysis we can conclude that neither the Severnaya Dvina River nor the Pechora River are likely to be major sources of anthropogenic PAHs to this particular region of the SE Barents Sea. On a general level, there are distinct similarities in PAH composition in the White Sea (Group 1) and SE Barents Sea. However a more detailed analysis of the di€erences in parent PAH ratios and on relative contents of alkylated homologues, indicates that the Kandalaksha aluminium smelter is probably not having a signi®cant impact at the o€shore SE Barents Sea location. Speci®cally, while the ¯uoranthene/(¯uoranthene + pyrene) ratio and benzo[b,k]¯uoranthene/ (benzo[b,k]¯uoranthene + benzo[e]pyrene) ratio are very similar in both data sets, the benzo[a]anthracene/ (benzo[a]anthracene + chrysene) ratio is elevated in the White Sea. In addition, the indeno[1,2,3-cd]/(indeno[1,2,3-cd] + benzo[ghi]perylene) ratio is much lower in the White Sea than in the SE Barents Sea. Given the strong signal of the aluminium smelter operations in sediments throughout the White Sea, it is plausible that areas of the Barents Sea closer to the White Sea contain a sedimentary PAH signature that is related to Kandalaksha smelter operations. Direct or indirect transport pathways are both viable mechanisms for distributing anthropogenic PAHs from Kandalak816

sha. The generalized circulation pattern of the lower atmosphere for the Barents region indicates a direct pathway is possible. In winter, frequent passages of Atlantic low pressure cyclones to the Barents Sea lead to predominantly south-westerly winds. Alternatively, indirect pathways may operate in conjunction with plume spreading across the Kola Peninsula and surface deposition on the coastal sea. These include marine transport (Loeng et al., 1997; P®rman et al., 1995a) or in wintertime incorporation into sea ice with subsequent transport and melting (P®rman et al., 1995b) in the Barents Sea. More extensive comparative investigations of PAH ®ngerprints in coastal Barents Sea areas are needed to document any e€ect.

Conclusions The composition and concentrations of aromatic hydrocarbons in bottom sediments of the White Sea indicate two primary station groupings. Pyrogenic PAHs predominate in seven of the eleven stations evaluated (Group 1). The highest pyrogenic PAH levels (including RCPAH) are detected in bottom sediments of the Kandalaksha Bay. Atmospheric discharges from the Kandalaksha aluminium smelter are most likely the predominant anthropogenic source of PAHs to the White Sea. At other stations, primarily located within the Dvina Bay, petrogenic PAHs and perylene predominate (Group 2). These are introduced into the Dvina Bay via the Severnaya Dvina River. Based on sediment age dating results at one location, present-day RPAH and RCPAH concentrations are 2-5 times higher than in the pre-industrial period. Both RPAH and RCPAH concentrations have decreased from 103 ng/g dw and 38.0 ng/g dw, respectively in 1957±1978 to 46.9 ng/g dw and 15.9 ng/g dw, respectively in 1994. PAH levels in the White Sea are lower than levels detected at one location 750 km from Kandalaksha in the SE Barents Sea. A comparison of ®ngerprints including alkyl-substituted homologues of parent PAHs and PAH ratios, indicates that neither the White Sea nor Pechora Sea areas are signi®cant sources of

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anthropogenic PAHs to this region of the SE Barents Sea. However, based on the observed widespread distribution of PAHs in the White Sea, atmospheric transport of particle-associated anthropogenic PAHs may very well be important in areas of the Barents Sea nearer to the Kandalaksha smelter. Funding for this investigation was provided by the Murmansk Marine Biological Institute of the Russian Academy of Sciences and by Akvaplan-niva. We thank the captain and crew of the RV ÔVsevolod BerjezkinÕ (Murmansk Hydrometeorological Service) and Lis Lindal Jùrgensen and Lars-Henrik Larsen (Akvaplan-niva) for managing and conducting the ®eld expedition. We wish to acknowledge the excellent analytical work performed by the Institute for Water Quality (Denmark) and UniLab (Norway). We thank one anonymous reviewer and Mark B. Yunker for substantive comments on the manuscript. Aizenshtat, Z. (1973) Perylene and its geochemical signi®cance. Geochimica and Cosmochimica Acta 37, 559±567. AREC, 1998. Arkhangelsk Regional Environmental Committee, 1997. Status and protection of the environment in Arkhangelsk region. Arkhangelsk: 88 p. (in Russian). Babkov, A. I. and Golikov, A. N. (1984) Hydrobiological complexes of the White Sea. ZIN USSR AS, L.: 104 p. (in Russian). Barrie, L. A. (1986) Arctic air pollution: An overview of current knowledge. Atmospheric Environment 20, 643±663. Barrie, L. A. (1991) Snow formation and process in the atmosphere that in¯uence its chemical composition. In Seasonal Snowpacks, eds. T. D. Davis, M. Tranter and H. G. Jones, vol. 28, pp. 1±20. NATO ASI Series, Springer, Berlin, Germany. Barrie, L. A., Gregor, D., Hargrave, B., Lake, R., Muir, D., Shearer, R,. Tracey, B. and Bidleman, T. (1992) Arctic contaminants: Sources, occurrence and pathways. Science Total Environment 23, 1±74. Bence, A. E., Kvenvolden, K. A. and Kennicut II, M. C. (1996) Organic geochemistry applied to environmental assessments of Prince William Sound, Alaska, after the Exxon Valdez oil spill-a review. Organic Geochemica 24, 7±42. Bidleman, T. F. and McConnell, L. (1995) A review of ®eld experiments to determine air±water gas exchange of persistent organic pollutants. Science Total Environment 159, 101±117. Boehm, P. D., Page, D. S., Gil®llan, E. S., Bence, A. E., Burns, W. A. and Mankiewicz, P. J. (1998) Study of the fates and e€ects of the Exxon Valdez oil spill on benthic sediments in two bays in Prince William Sound, Alaska. 1. Study design, chemistry, and source ®ngerprinting. Environmental Science and Technology 32, 567±576. Boehm, P. D. and Farrington, J.W. (1984) Aspects of the polycyclic aromatic hydrocarbon geochemistry of recent sediments in the Georges Bank region. Environmental Science and Technology 18, 840±845. Burns, W. A., Mankiewicz, P. J., Bence, A. E., Page, D. S. and Parker, K. R. (1997) A principal-component and least-squares method for allocating polycyclic aromatic hydrocarbons in sediment to multiple sources. Environmental Toxicology and Chemistry 16, 1119±1131. Byzova, N. M. (1995) Hydrobiological and ichtyological investigations of the White Sea. ZIN USSR AS, L. 103 p. (in Russian). Dobrovolsky, A. D. and Zalogin, B. S. (1982) The seas of USSR. Moscow State University Publishing House: 192 p. (In Russian). Grikurov, G. E. (1993) assessment of marine contamination in the Eurasian Arctic shelf by NPO Sevmorgeologia. In Proceedings of the Workshop on Arctic Contamination, Interagency Arctic Research Policy Committee. 2/7 May 1993, Anchorage, Alaska. Arctic Research of the United States: pp. 246±256. IARC (1987) IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. Overall evaluation of carcinogenity: an updating of IAPC monographs volumes 1-42. Suppl. 7. International Agency for Research on Cancer, Lyon, France. IOC (1982) International Oceanographic Commission. Manual and guides 11. The determination of petroleum hydrocarbons in sediments. UNESCO: 38 p.  Loeng, H., Ozhigin, B., Adlandsvik, B. and Sagen, H. (1997) Water ¯uxes through the Barents Sea. ICES Journal of Marine Science 54, 310±317.

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