ANNALES • Ser. hist. nat. • 10 • 2000 • 1 (19) original scientific paper UD C 547.912(Tr2aäki zaiiv) HYDROCARBONS IN SEA WATER AND COASTAL SEDIMENTS OF THE SLOVENIAN PART OF THE GULF OF TRIESTE Oliver 8AJT National Institute of Biology, Marine Biological Station, Sí-6330 Piran, Fornace 41 ABSTRACT In spite of the expected pollution of the marine environment of the Gulf of Trieste with hydrocarbons (heavy sea traffic, Ports of Koper, Trieste and Monfaicone), only a few data are available on the content of these compounds in sea water and sediment. This is the reason why the results regarding the content of hydrocarbons in sea water samples and surficial sediment from the southeastern part of the Gulf of Trieste are presented in this work. Aliphatic • and polyaromatic hydrocarbons were determined with the method of gas chromatography after the extraction from sediment. In the samples of sea water, the hydrocarbons were determined spectrofluorometrically. In view of the semblance and concentration of certain hydrocarbons, the most probable sources of pollution in this part of the Gulf of Trieste with hydrocarbons were stipulated. The results Indicate, on average, a significant pollution of the sea and surficial sediment with hydrocarbons. These are to a high extent of petrogenic and pyrogenic origin. A terrestrial input of natural hydrocarbons is also evident, which is in view of the fact that we are dealing with coastal water not unexpected at all. Key words: hydrocarbons, Gulf of Trieste, pollution, marine sediments !DROCARBURI IN ACQU A Di MARE E SEDIMENT1 COSTIER1 DELLA PARTE SLOVENA DEL GOLF O D! TRIESTE SI NT ESI Nonostante gli idrocarburi rappresentino un canco non indifferente per !'ambiente marino del Golfo di Trieste (visto Tintenso traffico marino, i porti di Capodistria, Trieste e Monfaicone ed II turismo náutico}, scarseggiano i dati riguardanti il contenuto di queste sostanze nell'acqua di mare e nei sedimenti. Ne.H'articolo vengono presentati i risultati della ricerca effettuata sul contenuto di Idrocarburi in campioni di acqua di mare e di sedimenti superficiali della parte sud-orientale del Golfo di Trieste. Gli idrocarburi alifatici e poliaromatici sono stati determinad con il método della cromatografía a gas, in seguito all'estrazione di questi dal sedimento. Nei campioni di acqua di mare gli idrocarburi sono stati determinad con la spettrofluorimetria. In base ai dati su presenza e concentrazione di determinad idrocarburi, sono state evidenziate le piu probabili fonti di inquinamento da idrocarburi in questa parte del Golfo di Trieste. Sia per l'acqua di mare che per i sedimenti superficiali, i risultati in media indicano un rilevante inquinamento da idrocarburi. La gran parle di questi é di origine petrogenica e pirogénica. E stala inoltre regístrala la presenza di idrocarburi naturali provenienti da térra ferma, dato prevedibile per le acque costiere. Parole chiave: idrocarburi, Golfo di Trieste, inquínamelo, sedimenti marini 6 1 ANNALES • Ser. hist. nat. • 10 • 2000 • 1 (19) Oärver ßAJTr HYDROCARBON S !N SEA WATE R AN D COASTAL SEDtMENTS OF THE SLOVENIA N PART O F THE GUL F O F TRIESTE. 61 -66 INTRODUCTIO N Hydrocarbons of natural and anthropogenic origin are widely distributed in the natural environment throughout the world. Different sources of introduction of these compounds into the natural environment can be stated. The most important among them are oil seepage, oil spillage, traffic, urban runoff, waste waters and sew­age effluents, as well as atmospheric deposition (GESAMP, 1993). Knowledge of the various sources of the introduction of such compounds into the marine environment as well as the concentrations of these compounds in sea water, sediment and marine organ­isms is of crucial importance to adequately assess the state of the environment. This is especially important where extensive industrial activity or traffic might be expected. Because of their hydrophobic nature and, as a con­sequence, of low solubility in water, hydrocarbons tend to adsorb on organic or inorganic particles in water col­umn. The enriched suspended matter is settled down to the sediment surface. In the sediment phase, hydrocar­bons are less subjected to physico-chemical or biologi­cal processes and may accumulate to higher levels. In this way the marine sediments often contain hydrocar­bons of higher concentrations than those in the overlay­ing water (Landrum & Robbins, 1990). Hydrocarbons, especially polyaromatic hydrocar­bons (PAH), have been recognized as hazardous envi­ronmental chemicals (GESAMP, 1993). They may act as narcotics to marine organisms, many of them are also carcinogenic and mutagenic (Donkin eta!., 1991; Simp-son et a!., 1996) due to their metabolic transformation products. Many of marine organisms living in contami­nated areas accumulate hydrocarbons (Baumard et a!., 1998). As a consequence, the elevated concentrations of these compounds in sea food could be harmful also for human health. These are important reasons for special attention devoted to this class of organic compounds. The aim of the present work was !o determine the content of hydrocarbons in surficial sediments and sea water in the southeastern (Slovenian) part of the Gulf of Trieste and to try to identify the origin of these com­pounds in this region. Despite several potential sources of pollution with hydrocarbons in this area only data for other parts of the Adriatic Sea are available (Dujmov & SuCevic, 1989; Guzzella & de Paolis, 1994). MATERIAL AN D METHODS Study area The investigated area in the southeast of the Gulf of Trieste is part of the Northern Adriatic {Fig. 1), The ma­rine environment along the coast is affected by pollution from different sources since this area is one of the most urbanized in the Northern Adriatic. Fig. 1: Sampling sites within the investigated area. SI. 1: Vzorčevalna mesta na preiskovanem območju. 62 ANNALES • Ser. hist. nat. • 10 • 2000 • 1 (19) Oärver ßAJTr HYDROCARBON S !N SEA WATE R AN D COASTAL SEDtMENTS O F THE SLOVENIA N PART O F THE GUL F O F TRIESTE. 61 -66 The estimated quantity of petroleum carried by ships to the three ports (Koper, Trieste, Monfalcone) in the Gulf of Trieste is about 30 millions tons per year. Beside the intensive maritime traffic, the nautical tourism is also well developed (3 marinas). Moreover, the marine envi­ronment within the studied area receives waste waters from several sewage treatment plants and fresh water from rivers, carrying also waste waters of the local in­dustry, as well as waters draining rather large agricul­tural areas. Coastal waters in this part of the Guif of Tri­este are used for some other economically important activities, like tourism, fisheries and maricuiture. Ac­cording to the above mentioned facts, the knowledge about the state of marine environment in this part of the Adriatic Sea is thus very important. Material and methods "Distilled in glass" quality hexane, methanol and methylene chloride (Fluka) were used for extraction of hydrocarbons. All other chemicals used throughout this work were of anaSyticai grade and purchased from Mer­ck (Germany). Na2 S04 , Silica, Alumina and extraction thimbles were precieaned by Soxhlet extraction with methanol and hexane (8 hours). Hg was rinsed several times with hexane. Samples of water were collected in 3 I precieaned (methanol, hexane) bottles at 1 m depth. Hydrocarbons were extracted with 100 mi of hexane and, additionally, twice with 50 ml of hexane. The hexane phase was dried with NajSC ^ and concentrated on rotary evapora­tor at ambient temperature to about 5 m!. Concentration of hydrocarbons was determined spectrofluorometricaily using a Turner 430 spectrofluorometer. The excitation and emission wavelengths were 310 and 360 nni, re­spectively. Calculations were made on chrysene stan­dard basts. Sediment samples were collected using a gravity core sampler (Meischner & Rumohr, 1974) at seven sites along the Slovenian part of the Gulf of Trieste (Fig. 1). The upper 1cm iayer of each sediment sample was taken for analysis. After freeze drying, the samples were extracted in Soxhlet apparatus with hexane and methyl­ene chloride (50:50) for 8 hours. The solution was con­centrated on rotary evaporator and additionally under nitrogen stream. After sulfur removal with mercury and additional concentration, partition of hydrocarbons was performed with column chromatography (Silica, Alu­mina). Concentrated extracts were analyzed using a H P 5890 gas chromatograph equipped with Ft detector and HP 3396 integrator. The HP Ultra 2 column (25 m X 0.32 mm, 0.17 pm film thickness) was used for analysis. C-32, n-octadecene and 9,10-dihydroanthracene were used as internal standards. Quantification was per­formed with external standards. RESULTS AN D DISCUSSION Concentrations of hydrocarbon in sea water are pre­sented in table 1. These results show somewhat higher concentrations of hydrocarbons only at sites 14 (Port of Koper) and P M (Portorož Marina), most probably due to the pollution from ships and boats. Tab. 1: Content of total hydrocarbons in sea water (in chrysene equivalents). Tab. 1: Vsebnost celotnih ogljikovodikov v morski vodi (v ekvivalentih krizena). Sampl. site/ date K (us/i) KK (pgfl) 14 (pg/l) P M tygft) M A lygfl) June 0.03 0.02 0.24 0.20 0.07 September 0.04 0.20 0.28 0.38 0.17 ; November 0.06 0.15 0.23 0.20 0.10 December 0.15 0.14 0.26 0.36 0.20 The amount of hydrocarbons in sea water at other sampling sites, compared with the results from the mid­dle and southern Adriatic sea (Dujmov & Sučevic, 1989), could be considered as relatively low. Concentrations of aliphatic hydrocarbons in sedi­ment samples are presented in table 2. The highest con­centrations were obtained at stations 14 inside the Port of Koper, P M at the entrance of Portorož Marina, K in the middle of the Bay of Koper and C Z in the center of the Gulf of Trieste, Pollution from boats and ships ap­pears as most probable the source of hydrocarbons at these locations. Moreover, site 14 is located in the estu­ary of the Rižana river and as such influenced by fresh water inputs, bringing also waste waters from the sew­age treatment plant of the city of Koper. Different sources of the elevated concentrations of hydrocarbons in the Bay of Koper could be presumed. Among them, the influence of the port of Koper, the direct influence of the runoff from the coastal road between Koper and Izola (Faganeli eta/., 1997) and atmospheric inputs (city of Koper) (Faganeli et a!., 1997) could be important sources of pollution in this bay. The content of hydro­carbons in surficial sediments in the center of the Gulf of Trieste (site CZ) seems to be dependent on the transport processes of particles on whic h hydrocarbons are asso­ciated, sedimentation and sorptive preservation on min­eral surfaces in mostly pelitic sediments (Hedges & Keif, 1995). O n the other hand, the lowest amount of hydro­carbons at the site f is most probably related to the lower degree of adsorption, since the sediment is mostly composed of silty sand (Ogoreiec et a!.. 1991). 63 ANNALE S • Ser. hist. nat. • 10 • 2000 • 1 (19) Oärver ßAJTr HYDROCARBON S !N SEA WATE R AN D COASTAL SEDtMENTS O F THE SLOVENIAN PART OF THE GUL F O F TRIESTE. 61 -66 Tab. 2: Aliphatic hydrocarbons in sediment samples (ng/g dry weight). Tab. 2: Alifatski ogljikovodiki v vzorcih sedimenta (ng/g suhe teže). CZ 74 PM K KK MA F n-heptadecane 21 17 18 7 5 8 5 Pristane 12 10 3 5 <1 <1 <1 n-odadecane 25 22 20 26 7 18 9 Phytane 17 15 10 17 <1 10 <1 n-CU to n-C34 193 182 216 117 71 78 49 Resolved aliphatics 268 246 267 197 83 114 63 UCM* ipig/0 1.73 2.45 1.97 2.85 1.42 0.57 0.93 Total aliphatic (pg/g) 2.00 2.70 2.24 3.05 1.50 0.68 0.99 *UC M unresolved complex mixture Concentrations of PAH, presented in table 3, fol­lowed a similar pattern of distribution to aliphatic hy­drocarbons. Only concentrations at site P M were ex­ceptionally high, with significant diversity of detected PAH. Tab. 3: Polyaromatic hydrocarbons in sediment sam­ples (ng/g dry weight). Tab. 3: Poliaromatski ogljikovodiki v vzorcih sedimenta (ng/g suhe teže). CZ 14 PM K KK MA F Naphthalene 9 4 5 3 <1 6 <1 1 -methylnaphthalene <1 <1 <1 <1 <1 <1 <1 l-ethylnaphthalerie <1 <1 <1 <1 <1 <1 <1 Acenaphtene <1 3 6 <1 <1 <1 <1 Acenaphtylene <1 <1 <1 <1 <1 <5 2,3,6-trimethyl-<1 <1 <1 <1 <1 <1 <5 naphthalene Phenanthrene 8 <1 45 17 10 6 <1 Anthracene 5 <1 14 14 7 3 <\ Fluorerie 6 72 10 6 6 <1 3 2-rnethylphenanthrene 18 11 15 19 13 8 <1 Í-methylphenanthwne 23 4 <2 21 6 <2 4 Fluoranthene 8 7 87 24 14 4 6 Pyrene 5 3 75 39 22 10 <1 3,6-dimethyl-<2 3 <2 <2 <2 <2 <2 phenanthrene Perylene <1 12 3 <1 <1 <1 <1 1-methylpyrene <1 <1 8 6 <1 <1 <1 Chrysene <1 <1 64 13 4 <1 <1 Beny.oj a!pyrene <1 <1 46 <1 <1 <1 <1 Benzo[e) pyrene 13 <1 53 <1 <1 <1 <1 BenzofaJanthracen e <1 <1 44 <1 <1 <1 <1 Resolved aromatic 86 113 484 162 82 31 13 Hydrocarbons may originate from different sources: biogenic, petrogenic and pyrogenic (La Flamme & Hites, 1978; Lipiatou & Saliot, 1991). A particular area may be affected from different sources of pollution and in such cases it is difficult to adequately distinguish between natural and mixed anthropogenic inputs. Different diag­nostic criteria, such as unresoIved/resolved hydrocar­bons ratio, carbon preference index and PA H distribu­tion pattern are used to determine the source of pollu­tion (Bouloubassi & Saliot, 1993). Applying these crite­ria, some conclusions may be assumed about the inves­tigated area. UC M was the major component of the ali­phatic hydrocarbon fraction, higher than 80 % (Tab. 2) at ail sampling sites. It consists of branched and cyclic hydrocarbons {Cough & Rowland, 1990) and is usually related to degraded petroleum residues (Farrington & Tripp, 1977). Fig. 2: Chromatogram of long-chain aliphatic hydro­carbon fraction (C21-C34) at site 14. Si. 2: Kromatogram vHjemolekularne frakcije alifatskih ogljikovodikov (C21-C34) na mestu 14. The compositional profile of n-alkanes showed a predominance of long-chain homologues (C2i - C34). A n elevated odd to even carbon number preference was detected especially at stations K and 14 (Fig. 2). Such distribution pattern of n-alkanes reveals the importance of terrestrial inputs in the study area (Saliot, 1981). The predominance of n-heptadecane, the hydrocarbon as­sociated with phytoplankton (Saliot, 1981), was not ob­served. This reflects most probably the labile character of short-chain n-alkanes and a moderate productivity in the study area (Fonda Umani et al., 1990). The presence of isoprenoid hydrocarbons pristane and phytane (Tab. 2) confirms the algal (Boehm, 1980) and anthropogenic (Anderlini ef aL, 1981) origin, respectively. Distribution of PAHs in surficial sediments within the study area revealed similar origin of hydrocarbons. The ratio of alkylated PA H homologues to parent com­pounds (especially for phenanthrene) was higher than 1 at all stations (except the station PM). This is an indica­tion of fresh petroleum pollution (Blumer & Youngblood, 64 ANNALES • Ser. hist. nat. • 10 • 2000 • 1 (19) Oärver ßAJTr HYDROCARBON S !N SEA WATER AND COASTAL SEDtMENTS O F THE SLO VENIA N PART O F THE GUL F O F TRIESTE. 61 -66 1975). The lower ratio a!ky!aied/parent PAHs was calcu­lated only for sediments in Portoro2 Marina (PM), indi­cating the predominance of combustion derived PAHs (Bfumer & Youngbiood, 1975). The appearance of py­rene, fiuoranthene, benzo[a]pyrene and benzo[e]pyrene at higher concentrations at sampling site P M confirms the prevalent pyrogenic origin of hydrocarbons (Sporstol et al., 1983). Fluoranthene and pyrene were detected in higher amounts in comparison to other sampling sites also at stations K and KK, This is an indication of pyrogenic pollution, originating probably from the Port and City of Koper (atmospheric deposition). The situation in the Port of Koper, regarding the appearance of PAHs, is somewhat surprising. The rather low concentrations of PAHs are most probably due to maintenance dredging and higher microbial degrada­tion, due to elevated number of bacteria from sewage treatment plant, especially in the summer period (Faganeli ef al., 1988). Perylene, a biogenic aromatic hydrocarbon (Saiiot, 1981), was detected at lower con­centration in the Port of Koper. This could be a confir­mation for terrestrial input, presumed already from the aliphatic hydrocarbon distribution. In conclusion, the southeastern part of the Gulf of Trieste is, regarding pollution with hydrocarbons, a considerably polluted area. Hydrocarbons in surficial sediments in the investigated area are mostly of petro­genic and pyrogenic origin. Some terrestrial influence is also evident in the Port of Koper and in the middle of the Bay of Koper. ACKNOWLEDGEMENTS The present investigation was part of the national monitoring program "The quality of sea water and con­trol of pollution in Slovenia", sponsored by Ministry of Environment and Civil Engineering of Slovenia and UNEPMEDPO L program. OGLJIKOVODIKI V MORSK! VOD! IN SEDIMENTU OBALNEGA MORJA SLOVENSKEGA DELA TRŽAŠKEGA ZALIVA O!i ver BAJT Nacionalni inštitut za biologijo, Morska biološka postaja, Sl-6330 Piran, Fornače 41 POVZETEK Ogljikovodiki, alifatski in PAH-i, so bili določeni v površinskem sedimentu slovenskega dela Tržaškega zaliva. • Analize so bile opravljene s plinsko kromatografijo. Vzorci morske vode z istega področja so bili analizirani spektrofluorometrično. Koncentracije raztopljenih/suspendiranih ogljikovodikov v morski vodi so razmeroma nizke. Le v Luki Koper in Marini Portorož so bile koncentracije nekoliko povišane, najverjetneje zaradi direktnega onesnaževanja z ladij in čolnov. Najvišje koncentracije alifatskih ogljikovodikov v površinskem sedimentu so bile izmerjene v Luki Koper, • Marini Portorož ter sredi Tržaškega in Koprskega zaliva. Na razporeditev ogljikovodikov vplivajo, poleg direktnega onesnaževanja z ladij in čolnov, tudi transportni procesi in procesi sedimentacije. Ti procesi so še posebno pomembni v obeh omenjenih zalivih. Razporeditev PAH-ov je bila podobna kot v primeru alifatskih ogljikovodikov. Koncentracije v Marini Portorož so bile izrazito višje, visoka pa je bila tudi raznolikost določenih PAH-ov. Povišana vsebnost PAH-ov je bila določena tudi v Luki Koper in sredi Koprskega zaliva. Izvor ogljikovodikov je bil določen po različnih kriterijih, v literaturi opisanih v te namene. 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