Polycyclic Aromatic Hydrocarbons in Seawater, Sediment, and Rock Oyster Saccostrea cucullata from the Northern Part of the Persian Gulf (Bushehr Province

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The concentration of polycyclic aromatic hydrocarbons (PAHs) was determined in seawater, sediment, and Rock oyster Saccostrea cucullata collected from four sampling sites in the inter-tidal areas of Bushehr province. The total concentrations of 14
  Polycyclic Aromatic Hydrocarbons in Seawater, Sediment,and Rock Oyster  Saccostrea cucullata  from the NorthernPart of the Persian Gulf (Bushehr Province) Roozbeh Mirza  &  Mehdi Mohammadi  & Ali Dadolahi Sohrab  &  Alireza Safahieh  & Ahmad Savari  &  Pavaneh Hajeb Received: 16 February 2011 /Accepted: 17 May 2011 /Published online: 7 June 2011 # Springer Science+Business Media B.V. 2011 Abstract  The concentration of polycyclic aromatichydrocarbons (PAHs) was determined in seawater,sediment, and Rock oyster   Saccostrea cucullata collected from four sampling sites in the inter-tidalareas of Bushehr province. The total concentrations of 14 PAHs varied from 1.5 to 3.6 ng/L in seawater, 41.7to 227.5 ng/g dry weight in surface sediment, and126 to 226.1 ng/g dry weight in oyster tissue. Incomparing PAH concentrations among the threematrices in Bushehr province, data showed that the pattern of individual PAHs in seawater, oyster, andsediment were different. The oysters tended toaccumulate the lower molecular weight and themore water-soluble PAHs. Sediment samples weredistinguished from the sea water and oyster samples by the presence of high molecular weight PAHs,especially six-ring PAHs. Three- and four-ring PAHswere the most abundant compounds among the 14PAHs investigated in surface seawater, sediment,and oyster samples. As expected, differences inoctanol/water partition coefficient among individualPAHs and the greater persistence of the higher molecular weight PAHs contributed to the accumu-lation patterns in oyster and sediment. The resultsof the study suggested that the main sources of PAHs in the seawater and sediment in the regionwere mixed pyrolitic and petrogenic inputs. Keywords  Polycyclicaromatichydrocarbons.Rock oyster .Sediment .Seawater .Boushehrprovince.PersianGulf  1 Introduction Polycyclic aromatic hydrocarbons (PAHs) are com-mon organic contaminants which derive mainly fromanthropogenic sources. Although a small amount isdue to natural processes, PAHs enter the near shoremarine environment by various ways such as spillageoil from ships, maritime transport accidents, andcombustion of fuels and municipal and industrialsewage (Vavalanidis et al. 2008; Vieites et al. 2004; Katsoyiannis et al. 2007; Boonyatumanond et al.2006; Viguri et al. 2002). Each individual source is characterized by a specificmolecular pattern, allowing the source of these com- Water Air Soil Pollut (2012) 223:189 – 198DOI 10.1007/s11270-011-0850-5R. Mirza  :  A. Safahieh :  A. SavariDepartment of Marine Biology,Faculty of Marine Sciences,Khoramshahr Marine Science and Technology University,Khoramshahr, IranM. Mohammadi ( * )Department of Marine Biotechnology and Environment,Persian Gulf Research and Studies Center,Persian Gulf University,Bushehr 75169, Irane-mail: mmohammadi@pgu.ac.ir A. Dadolahi SohrabDepartment of Environment, Faculty of Natural Sciences,Khoramshahr Marine Science and Technology University,Khoramshahr, IranP. HajebDepartment of Fisheries, Persian Gulf Research and StudiesCenter, Persian Gulf University,Bushehr 75169, Iran   pounds to be established (Guinan et al. 2001; Baumardet al. 1999). Molecular indices based on PAHs ’  physical – chemical behavior have been commonlyused to assess the differences between those of  pyrolitic and petrogenic srcin (Guinan et al. 2001;Baumard et al. 1998a; Budzinski et al. 1997). In the marine environment, PAHs are incorporatedinto the sediment from particulate sedimentation andfrom the biota. The biota assimilates PAHs from thewater column and the sediment. The concentration of PAHs in water column and sediment exhibits a widerange of toxicological effects to aquatic organismsincluding acute toxicity, development and reproductivetoxicity, photo-toxicity, mutagenic, and carcinogenicity(Vavalanidis et al. 2008; Gaspare et al. 2009; Delistraty 1997). PAHs due to their lipophilicity and lowsolubility in water tend to accumulation in sedimentsas well as in mussels and other marine invertebrates(Gaspare et al. 2009; Baumard et al. 1998 b). Bivalves have been extensively used as sentinelorganisms for monitoring persistent contaminants,including heavy metals and organic pollutions(Sericano et al. 1995; Wang et al. 2005). Rock  oyster,  Saccostrea cucullata , is filter feeding bivalvesthat are exposed to both dissolved and particulateform of lipophilic contaminants, including PAHs(Baumard et al. 1999).The Persian Gulf  ’ s contained environment makes it a natural repository for pollutants. Now, this marineecosystem is under stress from the impacts of unprecedented coastal reclamation, oil explorationand tanker movement, industrial developments, anddesalination projects. More than one million barrels of oil are spilled into the Persian Gulf annually; up to30% of sewage discharged into the sea is untreated;low levels of pollutants including pesticides and polychlorinated biphenyls have been found in marineorganisms and biota; heavy metals are relatively highnear the outfalls of desalination and power plants; andstudies report elevated concentrations of heavy metalsand petroleum hydrocarbons in the sediments, fishtissue, and water column (Sheppard et al. 2010).As a result, the Persian Gulf ecosystems facevarious challenges such as loss of biodiversity of fauna and flora, soil degradation, sediment andnutrient loss, a sharp decline in plant life, invasivespecies, and overgrazing. Persistent organic pollutionsmay also be incorporated into the food chain,affecting human health.It represents a stressed ecosystem because it issituated within the richest oil province in the worldand development pressure along its coastline. PersianGulf has about 800 offshore oil and gas platforms and25 major oil terminals (Sheppard et al. 2010). About 25,000 tanker movement sail in and out of the Strait of Hormuz annually. Because of these activities, it represents a stressed ecosystem.A few research has been reported on PAHsconcentration and distribution along the northern part of Persian Gulf  (Tolosa et al. 2005). Therefore, this study gives the first overview on the contaminationstatus and suggests possible sources PAHs in seawa-ter, sediment, and oyster samples from various coastalzones of Bushehr province. 2 Material and Methods 2.1 Sampling Location, Sample Collection,and PreparationThe study was carried out in the coastal environment (inter-tidal area) of Bushehr province. The samples of seawater, sediments, and oysters ( S. cucullata ) werecollected from four sampling sites, namely Genaveh,Bushehr, Dayyer, and Nyband Gulf as indicated inFig. 1. There are much industrialization and pipelinesin Genaveh. The main port of the province is locatedin Bushehr. The positions of sampling sites wererecorded using GPS (Table 1). All samplings wereconducted during July 2009.The samples of surface seawater (0 – 0.5 m) werecollected in 2 L of amber glass bottles which previously cleaned with dichloromethane and  n -hexane. The samples were stored under ice and inthe dark during transportation to the laboratory of Persian Gulf Research and Studies Center (PGRSC)and kept frozen ( − 20°C) until being analyzed.The samples of sediment were taken carefully fromthe surface sediments (0 – 5 cm) with a clean stainlesssteel spoon, from the four locations. Because of inactive input of terrestrial material to the bottomsediments of coastal environment caused by the lessinfrequent rain in the subtropical area, the top 2-cmlayers of the sediments are thought to represent modern input. Collected samples were immediatelytransferred to hexane rinsed glass jars with alumi-num foil inserts and transported in dry ice to the 190 Water Air Soil Pollut (2012) 223:189 – 198  laboratory of PGRSC and kept frozen at   − 20°C prior to analysis.Oysters ( S. cucullata ) were sampled from rocksand concrete using a chisel and hammer, wrapped inaluminum foil, and transported to the PGRSClaboratory. Oyster samples were stored at   − 20°C untilfurther analysis.2.2 PAHs ExtractionAll chemicals used were of analytical reagent grade.Dichloromethane (DCM) and hexane were of HPLCgrade. Oyster lipid and moisture analyses were madein triplicate on three composite samples comprisingof 1 g wet tissue (20 oysters) which were dried andground with sufficient sodium sulfate to obtain a free-flowing powder. These were added to a cellu-lose extraction thimble, Soxhlet extracted with a 1:1acetone/DCM solvent for 80 cycles. The extractedlipids were weighed after desiccation to determine percentage lipid content. Percent moisture content of  bivalve tissues was determined by gravimetry after drying the soft tissue of the bivalves in the oven(110°C) overnight  (Simpson et al. 2006). The extraction procedure for PAHs in sediment andoyster samples was carried out following the methoddescribed by Zakaria et al. (2002) and Zakaria andMahat (2006). Briefly, the samples of sediment andoysters were taken for dry weight determination. Thesamples were dried with anhydrous sodium sulfate(muffled at 300°C for 4 h) and mixed together for a homogenous mixture. A known concentration of PAHssurrogated internal standard mixture (naphtalene-d8 –  phenantherene-d10 –  p -terphenly-d14 – chrysene-d12 – Fig. 1  Sampling sites in the northern side of Persian Gulf, inter-tidal areas of coast of Bushehr province Table 1  Locations of sampling stationsStation Site no. Date LocationGenaveh 1 6/7/2009 29°39 ′  N, 50°24 ′  EBushehr 2 5/7/2009 28°50 ′  N, 50°52 ′  EDayyer 3 4/7/2009 27°49 ′  N, 51°55 ′  E Nyband Gulf 4 3/7/2009 27°24 ′  N, 51°38 ′  EWater Air Soil Pollut (2012) 223:189 – 198 191   perylene-d12) was added directly to the samples prior to extraction. The samples were extracted by Soxhlet for more than 8 h using DCM for sediment samplesand DCM and hexane mixture (1:1  v  /  v  ) for oyster samples following activated copper treatment for elemental sulfur removal. The extracted samples wereconcentrated until near dryness using rotary evaporator for further clean up. The concentrated extracts werecharged to first-step column chromatography (1 cm ininner diameter) packed with 5% silica gel deactivatedto remove polar compound. The eluants were collected,the volume was reduced to near dryness, and thencharged to second-step column chromatography(0.45 cm in inner diameter) packed with 100% fullyactivated silica gel to fractionate hydrocarbons. Thenthe mixture of DCM and hexane (3:1  v  /  v  ) was passedthrough the second-step column chromatography toelute the PAHs fraction. The PAH fractions wereevaporated to near dryness under gentle nitrogenstream and taken up to 200  μ L using iso-octane.Seawater samples were extracted using a liquid – liquid extraction (LLE) accordingto  Standard methods for the examination of water and wastewater   (APHA1992). A 2-L aliquot of seawater samples wassaturated with 150 g of sodium chloride and thentransferred into a 3-L separating funnel and extractedtriply by shaking vigorously with three portions of 30 mL dichloromethane solvent. The organic phaseswere separated and demoisturized with anhydroussodium sulfate. The extracted sample was reducedunder nitrogen and applied to silica gel column asdescribed above.2.3 Gas Chromatography – Mass SpectrometryAnalysisPAHs were analyzed by gas chromatography – massspectrometry using a HP 6890 series gas chromatog-raphy with mass detector equipped with a split/split less injector. The capillary column used for analysiswas a HP-5MS (Hewlett-Packard) 30×0.25 mm inner diameter×0.25  μ m film thickness. Oven temperaturewas programmed from 70°C (initial time 2 min) to150°C at the rate of 30°C min − 1 and from 150°C to310°C at a rate of 4°C min − 1 and was held at thistemperature for 5 min. The injector was maintained at 280°C. The carrier gas was helium at a constant flowrate of 1 mL min − 1 . A selected ion monitoring modewas employed using molecular ions of studiedPAHs. Quality control study was carried out bymonitoring recovery surrogate standards. The fivesurrogate standards were used for recovery correc-tion of PAHs. The acceptable range of recovery was between 40% and 120%. The relative standarddeviations of individual PAHs identified in sampleextracts were <10%. 3 Results and Discussions 3.1 PAHs Concentration and Origin in Seawater A total number of 12 samples of seawater, surfacesediment, and Rock oyster collected around Bushehr  province were analyzed for 14 individual PAH. Theconcentration of 14 compounds of PAH analyzed inthe seawater at four sampling sites ranged from1.8 ng/L at station 1 to 3.6 ng/L at station 4 (Table 2).Fourteen compounds of PAHs were investigated inthe samples; however, only eight PAHs were identi-fied at detectable levels. The highest concentrationwas observed at station 4. The results showed that theconcentration of PAHs in surface seawater in thenorthern of Persian Gulf is very low, compared toother areas in the Persian Gulf and worldwide. In thesimilar study, the total concentration of phenantherene,dibenzothiphene, fluoranthene, pyrene, and alkylhomologues in seawater samples of the northernPersian Gulf was 19 ng/L (Ehrhardt and Douabul1989). The dominant PAHs in that study were phenantherene and monomethylphenantherenes. Theresults of PAHs measured in the microlayer and sub-surface water of Venice (Italy) showed values of totalconcentration of PAHs ranged from 12.4 to 266.8 ng/L(Manodori et al. 2006). Concentration of the 15compounds PAH in waters of Baltic Sea ranged from0.5 to 14 ng/L (Witt  1995). That study showed that low molecular weight PAHs (two and three rings) weredominated in water samples. The total concentration( ∑ 17PAHs) in the surface seawater from the coastalareas of Sarnicos Gulf (Greece) ranged from 103 to459 ng/L (Vavalanidis et al. 2008).For the identification of the source of PAHs, weused two PAH ratios. Since phenantherene (Phe) and pyrene (Pyr) are more thermodynamically stable thantheir isomers, antheracene and fluoranthene, so a  192 Water Air Soil Pollut (2012) 223:189 – 198  Phe/Ant <10 and Flu/Pyr >1 indicate that thecontamination by PAHs is from a pyrolitic origin,while the PAH from petrogenic is characterized byPhe/Ant >10 and Flu/Pyr <1 (Baumard et al. 1998a, b; Budzinski et al. 1997; Vavalanidis et al. 2008). Our study showed that the samples of seawater inall sites have PAHs from mixed of pyrolitic and petrogenic srcin with predominant pyrolitic input at station 3. The sources of PAHs may srcinate from petrogenic sources in this area due to natural oilseeps, discharges of treated and untreated ballast and bilge water from oil tankers and other ships, effluentsfrom oil refineries, and oil/water separators on production platforms, while pyrogenic. PAHs weredue to activities such as atmospheric deposition andindustrial combustion. As shown in Table 2, in station1, Phe/Ant=0.72 (<10) and Flu/Pyr=0.65 (<1); instation 2, Phe/Ant=2.58 (<10) and Flu/Pyr=0.88(<1); in station 3 (Dayyer), Phe/Ant=0.92 (<10) andFlu/Pyr=1.1 (>1); and in station 4 (Nyband Gulf),Phe/Ant=1.23 (<10) and Flu/Pyr=0.5 (<1).3.2 PAHs Concentration and Origin in Sediment The total concentration of the 14 compounds of PAHinvestigated in surface sediment samples from inter-tidal areas of Bushehr ranged from 41.7 ng/g dw at station 4 to 227.5 ng/g dw at station 2 (Table 2).Among the areas surveyed, Genaveh (station 1) andBushehr (station 2) showed the highest concentrationof PAHs. The high pollution in these stations is probably due to industrial activities such as offshoreoil production in Khark and Kharku Island, oil/water separators on production platforms in Genaveh(Bahrekan), tanker traffic, and untreated sewage water discharged from municipal sewer.According to Baumard et al. (1998a), PAH levelscan be described as low, moderate, high, and veryhigh when  Σ PAH concentrations are 0 – 100, 100 – 1,000, 1,000 – 5,000, and >5,000 ng/g, respectively.On the basis of classification adapted by Baumardet al. (1998a), the sediment samples from the inter-tidal area of Bushehr can be considered low to Table 2  Polycyclic aromatic hydrocarbon in seawater (W; ng/L), sediment (S; ng/g dw), and oyster Station 1 Station 2 Station 3 Station 4W S O W S O W S O W S ODBT 0.15 11.99 12.84 0.02 28.66 32.54 Nd 31.99 15.85 0.17 7.37 6.22PHE 0.31 29.24 45.38 0.31 59.90 53.74 0.46 Nd 45.31 1.17 5.76 26.142MPHE Nd 64.53 33.42 Nd 86.70 77.46 Nd Nd 68.24 Nd 8.82 47.70ANT 0.43 12.81 11.42 0.12 30.45 15 0.50 7.74 Nd 0.95 2.85 6.39FLU 0.17 2.42 3.50 0.54 6.32 14.24 0.11 24.44 2.57 0.02 4.06 8.70PYR 0.26 3.69 5.28 0.61 4.72 15.77 0.10 26.47 6.92 0.04 4.86 10.661MPYR 0.28 6.94 8.48 1.32 2.92 29.82 0.29 21.57 2.78 Nd 0.16 16.23CHR 0.05 1.67 19.18 0.02 1.56 1.36 Nd 1.37 4.35 0.11 1.07 1.06BaA Nd 0.28 Nd Nd Nd Nd Nd Nd Nd Nd 2.92 NdBkF Nd Nd Nd Nd Nd Nd Nd 9.03 Nd Nd 3.83 22.77BeP 0.16 7.30 43.76 0.04 1.24 27.95 0.11 3.36 17.71 1.17 0.02 0.82BaP Nd 0.06 Nd Nd 2.93 0.18 Nd Nd Nd Nd Nd 0.15IND Nd 0.41 Nd Nd 2.17 Nd Nd Nd Nd Nd Nd NdBghiP Nd Nd Nd Nd Nd Nd Nd Nd Nd Nd Nd NdPhe/Ant 0.72 2.28  –  2.58 1.96  –  0.92 0  –  1.23 2.02  – FLU/Pyr 0.65 0.65  –  0.88 1.33  –  1.1 0.92  –  0.5 0.83  – ∑ PAHs 1.81 141.44 182.24 3.23 227.57 268.06 1.56 125.97 164.13 3.63 41.72 146.92  Nd   not detected,  DBT   dibenzotiophene,  PHE   phenentherene,  2MPHE   2 metyl phenentherne,  ANT  antheracene,  FLU   fluranthene,  PYR  pyrene,  CHR  chrysene,  BaA  benzo[a]antheracene,  BkF   benzo[k]fluranthene,  BeP   benzo[e]pyrene,  BaP   benzo[a]pyrene,  IND  indeno[1,2,3-cd]pyrene,  BghiP   benzo[ghi]pyreneWater Air Soil Pollut (2012) 223:189 – 198 193
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