Marine Pollution Bulletin 62 (2011) 1572–1576

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Marine Pollution Bulletin

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Baseline

Levels and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) insediments from Lenga Estuary, central Chile

Karla Pozo a,⇑, Guido Perra a, Valentina Menchi a, Roberto Urrutia b, Oscar Parra b, Anny Rudolph c,Silvano Focardi a

a Environmental Science Department, University of Siena, Via Mattioli 4, 53100 Siena, Italyb Center for Environmental Sciences EULA-Chile, Universidad de Concepción, Barrio Universitario s/n, casilla 160-C, Concepción, Chilec Facultad de Ciencias, Universidad Católica Santísima Concepción, Alonso de Ribera 2850, P.C. 407 01 29 Concepción, Chile

a r t i c l e i n f o

Keywords:PAHsSedimentsSQGLenga estuaryChile

0025-326X/$ - see front matter � 2011 Elsevier Ltd.doi:10.1016/j.marpolbul.2011.04.037

⇑ Corresponding author. Tel.: +39 0577232879; faxE-mail address: gallardokarla@gmail.com (K. Pozo

a b s t r a c t

The Lenga Estuary is a small brackish wetland located southwest of San Vicente Bay, Region VIII, Chile.Surface sediment from nine sites in the estuary were analysed for PAHs and compared to Sediment Qual-ity Guidelines (SQG). Sediment samples were freeze dried and soxhlet extracted for 16 h using DCM.Identification and quantification was carried out by HPLC. Organic carbon was also determined. Resultsshowed total PAH concentrations ranged from 290 to 6118 (2025 ± 1975) ng g�1 d.w. (2025 ± 1975).Results for organic carbon percentages ranged from 1% to 7%. Statistical analysis showed a significantpositive correlation (Pearson test) between organic carbon percentage PAHs. Comparison of contaminantlevels and international Sediment Quality Guidelines (SQG) (ERL and ER) suggested that sediment of theLenga estuary did not show any ecotoxicologial risk for benthic organisms where high levels of PAHswere detected. Monitoring of this and other contaminants is recommended in Chile.

� 2011 Elsevier Ltd. All rights reserved.

Estuaries are partly enclosed coastal bodies of water with one ormore rivers or streams flowing into them with a free connection tothe open sea (Pritchard, 1967). Estuaries form a transition zone be-tween river environments and ocean environments and are subjectto both marine influences, such as tides, waves, and the influx ofsaline water; and riverine influences, such as flows of fresh waterand sediment. The inflow of both seawater and freshwater providehigh levels of nutrients in both the water column and sediment,making estuaries among the most productive natural habitats inthe world (McLusky and Elliot, 2004) being nurseries for coastalfish and resting sites for migratory birds. In addition, because theycommunicate with the sea, many estuaries have been used asdumping sites for industrial and domestic effluents, turning theminto anaerobic digesters.

The Lenga estuary is a small coastal wetland (36�4700000S;73�1000000W) in Region VIII, central Chile (Fig. 1). It is located inthe Hualpen Nature Sanctuary and is listed in the inventory ofthe International Union for the Conservation of Nature (Scott andCarbonel, 1986; Gysel and Lyon, 1987). Heavy industrialisation be-gan in the 1950s, in the adjacent area of the estuary, in San VicenteBay, with construction of steelworks and an oil refinery. The lack ofregulation in those days, combined with industrial growth, has had

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: +30 0577232806.).

a heavy impact on the coastal ecosystem. The estuary also acts as acontaminant sink for the Biobio River, its major fresh water tribu-tary and one of the most polluted water bodies in the country (Par-ra and Faranda, 1993). The river receives the effluent of mills thatproduce 83% of Chilean wood pulp production (Gonzalez et al.1999) and of sewage treatment plants as well as run-off from thecatchment area. Industrial activities and the river determine a con-siderable sediment load with high organic carbon content whichcan act as an efficient pollutant trap.

Polycyclic aromatic hydrocarbons (PAHs) are persistent toxiccompounds that bioaccumulate in wildlife (UNEP, 2001). Contam-ination of PAHs in sediments may pose unacceptable risks foraquatic organisms, wildlife and humans. Awareness of risks to hu-mans and the environment from contaminated sediments caninfluence regulatory decisions (regarding, for example, dredging,swimming, fishing, shoreline rehabilitation). Because sedimentchemistry data alone does not provide an adequate basis forassessing the hazards posed by sediment-associated contaminantsfor aquatic organisms, interpretative tools are required to deter-mine their potential concentration risk to the aquatic environment.Sediment Quality Guidelines (SQG) provide a scientifically justifi-able basis for evaluating the potential effects of sediment-associ-ated contaminants on aquatic organisms. Sediment QualityGuidelines (SQG), such as effects range low (ERL) and effects rangemedian (ERM), are valuable for establishing empirical relationshipsbetween expected incidences of toxicity and the number and/or

Fig. 1. Map of sampling sites in the Lenga estuary, Region VIII, central Chile.

K. Pozo et al. / Marine Pollution Bulletin 62 (2011) 1572–1576 1573

degree to which SQGs values are exceeded. Recently, this approachhas been applied to others coastal sites around the world. For in-stance, Cardellicchio et al. (2007) used SQGs to provide possibleecotoxicological risk estimations for benthic organisms at Mar Pic-colo in Taranto, southern Italy and Binelli et al., 2008 reported acomparison of SQGs for toxicity assessment in the Bay of Bengalin India.

In Chile, various coastal ecosystems are subject to anthropo-genic influence but limited information is available on PAH levels.Previous studies have documented contamination by PAHs in cen-tral Chile in lake sediments (Barra et al., 2004; Quiroz et al., 2005),organisms (Barra et al., 2005) and marine environments (Mudgeand Seguel, 1999; Rudolph et al., 2002). In this study, we reportlevels and distribution of PAHs in superficial sediments of the Len-ga estuary. To evaluate the quality of sediments and to assess ad-verse biological effects in benthic organisms we used effect-based Sediment Quality Guidelines (SQGs) for PAHs.

Superficial sediments (10–20 g) were obtained with a grab sam-pler in nine stations of the Lenga estuary during July 2002 (Fig. 1).Sediment samples consisted mainly of coarse and medium sand(76%) at most of the stations with the exceptions of stations 7, 8and 9 where fine and muddy clays were dominant. Samples weretaken to the laboratory in an ice cooler, where they were weighedand sealed to avoid contamination. Before analysis, sedimentswere freeze dried at �50 �C and 0.2 mbar. For extraction of PAHs,dry sediments (5–10 g) were homogenised with clean anhydroussodium sulphate (previously extracted by a soxhlet system). Sedi-ment samples were placed in pre-cleaned cellulose thimbles, andextracted by soxhlet for 18 h with dichloromethane (DCM)(300 ml). Extracts were percolated through activated copper to re-move sulphur, concentrated by rotavapor and exchanged into hex-ane solvent (1 ml). For PAHs, clean-up extracts were concentratedin a rotary evaporator to about 0.5 ml, and run on a silica gel col-umn activated at 130 �C over night. The silica column was slurrypacked with 20 ml of hexane. Then, PAHs extracts were eluted with15 ml of DCM/Hexane (1:1) and reduced to 1 ml of acetronitrile(Cousins and Jones, 1998 with some modifications).

PAH identification and quantification was performed utilisingHPLC on a Waters (Milford, MA, USA) liquid chromatographic

system, with a Waters 474 Scanning Fluorescence Detector andWaters 996 Photodiode Array Detector, using a Supelcosil-PAHscolumn (250 � 4.6-mm I.D., particle size 5 lm). A mobile phaseflow rate of 1.5 ml/min was used with the following linear gradientelution program: acetonitrile:water (v:v) in a linear gradient from40:60 in 1 min to 100:0 in 25 min maintaining this ratio for 15 minand going back to 40:60 in 4 min. The column temperature wasmaintained at 25 �C. Each sample was quantified for 16 PAHs pro-posed by EPA as priority pollutants (see Table 1). Fluorescencedetection was optimised with wavelength (kex(nm)) programmingfor the excitation and emission as follow: Naph (220–330), Ace(270–323), Fl, Phen, Ant (248–374), Flu (237–460), Pyr, BaA, Chr(270–400), BbF, BkF, BaP, DBA, BgP (290–418) and IP (270–490).Acenaphthylene has the weakest fluorescence and must be deter-mined by UV absorbance. PAHs concentrations were expressed inng g�1 d.w.

The above procedures were checked for recoveries and repro-ducibility. Procedural blanks and reference material purchasedfrom the National Institute of Standards and Technology (NIST)was analysed for QA/QC purposes. Analysis of PAH reference mate-rial (HS-6) showed a mean recovery of 95%. Prior to sedimentextraction, six analytical blanks were prepared using the sameextraction and clean-up procedure. A solvent blank was analysedafter every 15 samples to check the chromatographic response.Limits of detection (LODs) were defined as the average blank(n = 4) plus three standard deviations (SD). When target com-pounds were not detected in blanks, 2/3 of the instrumental detec-tion limit was used as the method detection limit (MDL). Allqualified data (i.e., exceeding the MDL) were blank corrected. MDLsranged from 0.01 to 0.5 ng g�1 for PAHs.

In order to evaluate the possibility of adverse effects in sedi-ments of the Lenga estuary, concentrations of PAHs were comparedto international SQGs. SQGs were limited to the use of the effectsrange low (ERL) and effects range median (ERM) weight-of-evi-dence approach of the National Oceanic and Atmospheric Adminis-tration (NOAA) (Long et al., 1995; MacDonald et al., 1996).

Organic carbon analysis was carried out with 0.1–0.5 g of drysediment thoroughly mixed with 10 ml potassium dichromate(K2CrO7, 1 N). Concentrated sulphuric acid (20 ml) was added,

Table 1Concentrations (ng g�1 d.w.) of 16 priority polycyclic aromatic hydrocarbons (PAHs) and organic carbon (%) in superficial sediments of Lenga estuary.

Compound/station MDL L1 L2 L3 L4 L5 L6 L7 L8 L9

Naphthalene 0.25 6 bdl 3 5 15 15 29 7 16Acenaphthylene 0.50 bdl bdl bdl bdl bdl bdl bdl bdl bdlAcenaphtene 0.05 106 6 18 347 60 bdl 134 41 73Fluorene 0.04 10 3 3 bdl 13 3 40 5 10Phenanthrene 0.01 131 36 41 334 116 18 440 49 114Anthracene 0.01 45 11 10 120 40 6 180 19 38Fluoranthrene 0.01 390 86 120 798 350 56 1050 140 215Pyrene 0.04 369 109 91 1017 272 36 953 86 144Benz[a]anthracene 0.02 123 41 58 247 166 22 425 47 86Chrysene 0.02 173 51 82 124 224 21 457 54 108Benzo[b]fluoranthene 0.01 164 51 72 254 200 24 575 128 82Benzo[k]fluoranthene 0.01 85 25 32 209 76 13 234 25 36Benzo[a]pyrene 0.02 207 56 111 313 226 22 564 68 121Indeno[1,2,3-cd]pyrene 0.02 87 4 9 167 110 15 327 17 10Dibenzo[a,h]anthracene 0.10 108 23 59 161 135 18 312 27 48Benzo[g,h,i]pyrene 0.03 128 50 47 228 130 21 398 45 62

Tot PAHsa 2131 551 757 4323 2134 290 6118 757 1162Mean 133 39 50 309 142 21 408 50 77SD 113 31 39 273 98 13 295 40 57Organic carbon (%) 1 2 2 7 4 2 4 1 1

Abbreviations: MDL, method detection limit; bdl, below detection limit; SD; standard deviation.a RPAH16: 2-ring PAHs include naphthalene; 3-ring PAHs include acenaphthylene, acenaphthene, fluorene, phenanthrene and anthracene; 4-ring PAHs include fluo-

ranthene, pyrene, benzo[a]anthracene and chrysene; 5-ring PAHs include benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and dibenzo[ah]anthracene; 6-ringPAHs include indeno[1,2,3-cd]pyrene and benzo[ghi]pyrene.

Total PAHs

0

1000

2000

3000

4000

5000

6000

7000

L1 L2 L3 L4 L5 L6 L7 L8 L9

Conc

entra

tions

(ng/

g d.

w)

Organic Carbon (%)

0

1

2

3

4

5

6

7

8

L1 L2 L3 L4 L5 L6 L7 L8 L9

Perc

enta

ge (%

)

a

b

Fig. 2. PAH concentrations (ng g�1 d.w.) (a) and OC (%) (b) in superficial sedimentsof the Lenga estuary.

L1L2L3L4L5L6L7

L8L9

2RP

AH

s

3RP

AH

s

4RP

AH

s

5RP

AH

s

6RP

AH

s

0

20

40

60

Fig. 3. Homologue composition (%) of polycyclic aromatic hydrocarbons (PAHs) insediment from the Lenga estuary.

1574 K. Pozo et al. / Marine Pollution Bulletin 62 (2011) 1572–1576

and the mixture was shaken for 30 s and left to rest for 30 min. Thesample was diluted to 100 ml with distilled water containing 10 mlphosphoric acid (H3PO4) and 0.2 g sodium fluoride (NaF). Finally,samples were cooled and titrated with ferrous ammonium sul-phate Fe8(NH4)2(SO4)2 0.5 N (Gaudette et al., 1974; Pozo et al.,2007, 2009). The statistical analysis was performed with the SASstatistical software package (SAS, Version 7). Pearson correlationwas used to analyse relationships between PAHs and organic car-bon percentage (%).

Table 1 shows PAH concentrations and carbon content (%) insediments of the Lenga estuary. Total concentrations of PAHs(ng g�1 d.w.) ranged from 290 to 6118 (2025 ± 1975). Spatial

distribution patterns shows that the highest PAH concentrations(ng g�1 d.w.) were found at stations L7 (6118), L4 (4319) and L5(2134) (Fig. 2a). These results are higher than PAH levels detectedin other coastal areas of Chile. For instance, Mudge and Seguel(1999) reported 1–210 ng g�1 d.w. in sediments of San VicenteBay. Rudolph et al. (2002) reported PAH concentration (lg/kg) ofanthracene (<0.05–159), phenanthrene (64–281), fluoranthrene(141–706) and pyrene (<0.05–572) in sediments of ConcepciónBay, central Chile. However, PAH levels detected in this study aresimilar to those of highly PAH-polluted sites in other parts of theworld. Tan and Heit (1981) reported levels up to 12,100 ng g�1 inLake Woods, USA; Hong et al. (1995) found values of 1200–14,000 ng g�1 in Victoria Harbour, Hong Kong, China; Baumardet al. (1998) detected levels of 900–4100 ng g�1 in Arcachon Bay,France; Meniconi et al. (2002) found 91–8035 ng g�1 in Guanabara

K. Pozo et al. / Marine Pollution Bulletin 62 (2011) 1572–1576 1575

Bay in Brazil; and Medeiros et al. (2005) detected a range of 38–11,780 ng g�1 at Patos Lagoon estuary in Brazil.

PAH composition pattern was dominated by four- (48%) andfive-ring (26%) PAHs (Fig. 3). Of the individual PAHs analysed, flu-oranthene and pyrene accounted for 40% and 30% of total PAHscomposition, respectively. Ratios of phenanthrene/anthraceneand fluoranthene/pyrene were also estimated in order to distin-guish between PAHs of different origin. The phenanthrene/anthra-cene ratio is temperature-dependent and is approximately 3 foremissions from the combustion of various fuels (Gschwend andHites, 1981). Predominance of fluoranthene/pyrene is classicallyof pyrolytic origin, namely coal combustion (Simo et al., 1997). Inthe Lenga estuary, the average PAH ratio was 3 for phenan-threne/anthracene and 1.2 for fluoranthene/pyrene, indicating apyrolytic origin of the predominant PAH compounds.

Interesting results were also obtained for potentially carcino-genic PAHs (benzo[a]anthracene + benzo[b]fluoranthene + benzo-[k]fluoranthene + benzo[a]pyrene + indeno[1.2.3-cd]pyrene + dibenzo[ah]anthracene) with concentrations (ng g�1 d.w.) ranging from 114 to2437 accounting for 33–54% of the total PAHs composition. In partic-ular, pyrene and benzo[a]pyrene showed high levels at stations L4and L7 (Table 1). It was also noteworthy that naphthalene, the sim-plest low molecular weight PAH, was found at relatively high levels,suggesting that its contribution was mainly from anthropogenicsources.

Evaluation of potential ecotoxicological risk was also estimated.SQG calculations such as effects range low (ERL) and effects rangemedian (ERM) were used to evaluate sediment quality in relationto PAH levels in the Lenga estuary. Table 2 presents the concentra-tion ranges of PAHs proposed by international SQGs (ERL–ERM)and the number of stations amongst ranges of international SQGsat Lenga estuary. SQG values showed that PAHs exceeded theERL for total PAHs (4.0 � 103 ng g�1 d.w.) only at two stations(L4 = 4323 and L7 = 6118), and no stations exceeded the ERM(44 � 103 ng g�1 d.w.). With the exception of dibenzo[ah]anthra-cene at station L1, individual PAHs did not exceed the ERL(Table 2).

Organic carbon percentage (OC%) fluctuated between 1% (L1)and 7% (L4) (Table 1 and Fig. 2b). These results are in agreementwith the OC% reported in other coastal areas of Chile. Moscosoet al. (2006) reported OC% of 1.9–6.8% in the Lenga estuary, Silvaet al. (1998) detected average OC% of 5.8 ± 1.8 in Chilean Fjiords,Southern Chile and Aguirre-Martínez et al. (2009) found OC% about6% in Caleta Coliumo–Central Chile. Statistical analyses showedsignificant positive correlations between OC% and PAH

Table 2SQGs values for PAHs and number of stations amongst ranges of internationalSediment Quality Guidelines at Lenga estuary.

Compound SQGa ERL–ERM (ng g�1 d.w.) No. of stations<ERL ERL–ERM >ERM

Naph 160–2100 L9 – –Acy 44–640 L9 – –Ace 16–500 L2 L7 –Fl 19–540 L8 L1 –Phen 240–1500 L7 L2 –Anthr 85–1100 L7 L2 –Fluo 600–5100 L7 L2 –Pyr 665–2600 L7 L2 –B[a]A 261–1600 L8 L1 –Chry 384–2800 L8 L1 –B[b + k]Fl – – – –B[a]P 430–1600 L8 L1 –IDP – – –DB[ah]A 63–260 L5 L3 L1B[ghi]P – – – –RPAHs 4022–44,792 L7 L2 0

a SQG values taken from Long et al. (1995) and MacDonald et al. (1996).

concentrations (r = 0.73; p < 0.05) at the Lenga estuary. These re-sults indicated that OC content is a good indicator of adsorptionof organic contaminants by suspended particulate matter. Conse-quently, the subsequent sedimentation process is also an impor-tant factor that enhances the transport, diffusion and fate ofthese compounds in the estuary.

In conclusion, these results show that concentrations of PAHswere high and similar to those recorded in others highly PAH pol-luted sites of the world. The ecotoxicological evaluation based oninternational SQGs indicates no ecotoxicological risk for benthicorganisms exposed to relatively high levels of PAHs. However,damage might also occur at lower concentrations than those usedas guidelines. For instance, Thomas et al. (1999) reported potentialphysiological tolerance for those organisms exposed chronically toPAHs levels. Further studies for other potential contaminants (i.e.,pesticides, PCBs, PCDD/Fs) are recommended in other coastal eco-systems in Chile. In addition, education of the general public aboutthe hazards associated with production of toxic compounds isessential for long-term mitigation of potential environmentalproblems. These results are an important contribution to knowl-edge of levels of PAHs in estuary ecosystems in Chile.

Acknowledgements

This work was supported by the international collaborationagreement between Siena University and Concepción University,which permits the academic interchanges and to conduct researchin the Biobío and Patagonia Regions in Chile. We also want to thankUNESCO-EOLSS Chair in Natural Resource Management, LandPlanning and Environmental Protection and to project FondecytN�1070508 and N�1080294 for their partial support.

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