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Distribution of trace organic contaminants and total mercury in sediments from the Bilbao and Urdaibai Estuaries (Bay of Biscay)
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
manuscript is contribution number AED-06-047 of the Atlantic Ecology Division of the United States Environmental Protection Agency, Office of Research and Development, National Health Effects Environmental Research Laboratory. Mention of trade names does not constitute endorsement or recommendation for use. References Abramowicz, D.A., Brennan, M.J., Van Dort, H.M., Gallagher, E.L., 1993. Factors influencing the rate of polychlorinated biphenyl dechlorination in Hudson River sediments. Environ. Sci. Technol. 23, 1125– 1131. Agency for Toxic Substances and Disease Registry (ATSDR), 2000. Atlanta, GA: US Department of Health and Human Services, Public Health Service. Available from:
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Hartmann, P.C., Quinn, J.G., Cairns, R., King, J.W., 2004. Polychlorinated biphenyls in Narragansett Bay surface sediments. Chemosphere 57, 9–20. Hutzinger, O., Safe, S., Zitko, V., 1974. The Chemistry of PCBs. CRC Press, Cleveland, OH, pp. 1–269. Kannan, K., Maruya, K.A., Tanabe, S., 1997. Distribution and characterization of polychlorinated biphenyl congeners in soil and sediments from a superfund site contaminated with Aroclor 1268. Environ. Sci. Technol. 31, 1483–1488. Kannan, K., Nakata, H., Stafford, R., Masson, G.R., Tanabe, S., Giesy, J.P., 1998. Bioaccumulation and toxic potential of extremely hydrophobic polychlorinated biphenyl congeners in biota collected at a Superfund site contaminated with Aroclor 1268. Environ. Sci. Technol. 32, 1214–1221. Ko, F.C., Baker, J.E., 2004. Seasonal and annual loads of hydrophobic organic contaminants from the Susquehanna River Basin to the Chesapeake Bay. Mar. Pollut. Bull. 48, 840–851. Latimer, J.S., 1989. Polychlorinated biphenyls in Narragansett Bay. Ph.D. Dissertation Oceanography University of Rhode Island Narragansett RI, p. 413. Latimer, J.S., Quinn, J.G., 1996. Historical trends and current inputs of hydrophobic organic contaminants in an urban estuary: the sedimentary record. Environ. Sci. Technol. 30, 623–633. Maruya, K.A., Lee, R.F., 1998. Aroclor 1268 and Toxaphene in fish from a Southeastern US Estuary. Environ. Sci. Technol. 32, 1069–1075. Menzie-Cura & Associates, 2000. Muddy Cove ecological risk assessment. Monsanto Chemical Company, 1944. Salesmen’s manuals for Aroclor products. p. 41. Available from:. Morrison, R.D., 2000. Critical review of environmental forensic techniques: Part I. Environ. Foren. 1, 157–173. Reible, D.D., Popow, V., Valsaraj, K.T., Thibodeaux, L.J., Lin, F., Dikshit, M., Todaro, M.A., Fleeger, J.W., 1996. Contaminant fluxes from sediment due to tubificid oligochaete bioturbation. Water Res. 30, 704–714. United States Department of Agriculture, 1972. Polychlorinated biphenyls and the environment. Interdepartmental Task Force on PCBs. Report No. ITF-PCB-72-1, p. 189.
0025-326X/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2006.05.019
Distribution of trace organic contaminants and total mercury in sediments from the Bilbao and Urdaibai Estuaries (Bay of Biscay) L. Bartolome´, I. Tueros, E. Cortazar, J.C. Raposo, J. Sanz, O. Zuloaga *, A. de Diego, N. Etxebarria, L.A. Ferna´ndez, J.M. Madariaga Kimika Analitikoaren Saila, Euskal Herriko Unibertsitatea, 644 PK, E-48080 Bilbao, Spain
The estuary of Bilbao is one of the most industrialised and populated areas of the Bay of Biscay. Due to its geographic location, as well as its natural richness in mineral resources, the area has been subjected to intense industrial
*
Corresponding author. Tel.: +34 94 601 3269; fax: +34 94 601 3500. E-mail address: [email protected] (O. Zuloaga).
pressure (Azkona et al., 1984). For many years, urban and industrial effluents were discharged into the estuary without further treatment. By the 1970s, water sampling revealed extremely low oxygenation together with high organic matter and heavy metal concentrations (Cearreta et al., 2000; Sainz-Salinas et al., 1996). In 1979, an Integral Plan for the Drainage of the estuary was approved and new environmental protection policies resulted in improved
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wastewater treatment systems. This, together with the closure of several industries, has produced a gradual recovery of the estuarine environment, with a continuing decrease in heavy metal concentrations and an increase in oxygenation. The estuary of Bilbao (Fig. 1(a)) has been considerably constrained from its original state. The tidal channel flows into El Abra Bay, which is 3.5 km in width and 30 m in depth. The tidal zone of the Ibaizabal River forms the estuary, although four tributaries (Kadagua, Asua, Galindo and Gobela) also discharge in the estuary. There are docks and secondary channels (the channel of Deustu and the docks of Axpe, Udondo, La Benedicta, Lamiako and Portu) in the upper zone of the estuary. This area was the most affected by urban and industrial wastes (Cearreta et al., 2000). The estuary of Urdaibai and its surroundings have been a reserve since 1984, and are located in a rural environment about 50 km east from the Ibaizabal valley. The Urdaibai region (Fig. 1(b)) is characterised by the basin of the Oka River, and by some shorter rivers, including the Golako, Mape, Artike and Laga. The estuary, some 13 km long and 500 m wide, is located in relatively close proximity to
several industries (metallurgic, shipyards, dyes, cutlery manufacture) located in the surroundings of Gernika (population 20,000) upstream the Oka River (Irabien and Velasco, 1999). This paper reports (1) the spatial and seasonal variation of Hg, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and phthalate esters (PEs) in both estuaries; (2) the association of total concentration of these contaminants with particle size and TOC; and (3) the origin of these contaminants. Sediments were collected during five different sampling periods (December 2001, June 2002, September 2002, November 2002 and February 2003) at four sites in the estuary of Urdaibai and during two sampling periods (November 2002 and February 2003) at 12 points in the estuary of Bilbao. Fig. 1 shows the sampling points in both estuaries. Surficial sediment samples were collected by hand, stored in pre-cleaned glass flasks and transported to the laboratory in cool boxes. Once in the laboratory, the sediments were frozen and lyophilised at low temperatures (46/52 C) and pressures (0.17/0.22 mbar) in a Cryodos-50 freeze-drier (Telstar, Spain). The freeze-dried samples were treated in
Fig. 1. Sampling points in the estuaries of (a) Bilbao (1 = Bilbao; 2 = Deustu; 3 = Zorrotza; 4 = Kadagua; 5 = Portu; 6 = Galindo; 7 = La Benedicta; 8 = Lamiako; 9 = Gobela; 10 = Udondo; 11 = Axpe and 12 = Asua) and (b) Urdaibai (A = Kanala; B = Arteaga; D = Gernika and E = Murueta).
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
two different ways. Samples collected before February 2003 were ground in a ball grinder (Fristch Pulverisette 6, Germany), sieved (250 lm), stored in glass vials and kept at 4 C until analysis. Sediments from February 2003 were freeze-dried and then sieved at three different particles sizes: (i) sand, >250 lm; (ii) silt, 250 lm and (iii) clay, <63 lm. The smallest two fractions were stored at 4 C until analysis. The sand, silt and clay contents of these sediments were estimated by weighing the different fractions using an analytical balance. The sediments were further characterised by measuring total organic carbon (TOC) by the Walkley–Black titration method (Leong and Tanner, 1999). For the analysis of organic compounds, 1.0 g of dry sediment was accurately weighed and submitted to microwave-assisted extraction in 15 ml of acetone at 21 psi for 15 min and at 80% of microwave power in a MDS-2000 microwave (CEM, Matthews, NC, USA), after 25 ll of a mixture of acenaphthene-d10, chrysene-d12 and phenanthrene-d10 at 20 lg ml1 in acetone and 25 ll of a mixture of dibenzyl phthalate, diphenyl isophthalate and diphenyl phthalate at 20 lg ml1 in acetone were added as internal standards. The extract was concentrated under a gentle stream of nitrogen and loaded onto a 1 g Florisil cartridge (Supelco, Walton-on-Thames, UK) for further clean-up of the sample. PAHs and PCBs were eluted in 12 ml of a (4:1) n-hexane:toluene mixture and PEs in 5 ml of ethyl acetate. The eluates were concentrated to dryness, re-dissolved in 500 ll of iso-octane and kept in the dark at 18 C until analysis (Bartolome´ et al., 2005). The extracts were analysed in a 6890 N Agilent gas chromatograph coupled to a 5973 N Agilent mass spectrometer (Agilent Technologies Inc., Avondale, PA, USA) with a 7683 Agilent autosampler. 2 ll of sample were injected in splitless mode at 270 C into a 30 m · 0.25 mm · 0.25 lm HP-5 capillary column (Agilent Technologies Inc.). The method summarised above was validated in our laboratories using the certified reference marine sediment NIST 1944 (Gaithersburg, MD, USA) in the case of PAHs and PCBs and by comparison of different extraction techniques for phthalate esters (Cortazar et al., 2005). Regarding total mercury, 0.5 g of sediment were weighed, transferred into borosilicate vessels and digested in 20 ml of HCl (5 mol l1) in the microwave cavity of a focused Microdigest 3.6 microwave oven (Prolabo, France) for 12 min at 63% of microwave power (Sanz, 2002). Once the extraction period was completed, the extract was centrifuged, diluted to 50 ml and analysed by quartz furnace atomic absorption spectrometry (QFAAS; 4110 ZL spectrometer, Perkin Elmer) after hydride generation (HG) of the sample in a FIA system (FIAS 400, Perkin Elmer). The analysis was performed using the standard conditions recommended by the manufacturer (Perkin Elmer, 1994). The analysis of mercury was validated using NIST 1944, PACS-1 and CRM-580 materials, with satisfactory results (Sanz, 2002). Blank samples were processed in the same way as sediment samples in order to estimate the detection limits (1–
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22 lg kg1 for PAHs, 1–3 lg kg1 for PCBs, 1–43 lg kg1 for PEs and 0.6 lg kg1 for total mercury). A number of sediment samples were analysed in duplicate in order to calculate the repeatability of the method. The relative standard deviations (RSD) estimated in this way were lower than 20% for all the analytes studied, except for bis (2-ethyl-hexyl) phthalate (DEHP) with a RSD value of 40%. The results obtained for the total concentrations of PAHs, PCBs, PEs and Hg are summarised in Figs. 2 and 3 for the estuaries of Urdaibai and Bilbao respectively. In order to calculate the total concentration of each group of contaminant, the concentration of each congener or isomer was taken into account, including the values below the detection limits (where half of the detection limit was used). The estuary of Bilbao showed higher contaminant concentrations than Urdaibai. The organic matter content in the former ranged from 1.8% to 9.9%, while in the estuary of Urdaibai the values were between 1.6% and 5.4%. For PAHs and PEs, the differences were more significant. While the contents of PAHs and PEs ranged from 0.7 to 300 mg kg1 and from 0.8 to 140 mg kg1 respectively in Bilbao, the estuary of Urdaibai showed values between 0.7–7.2 mg kg1 and 0.05–14 mg kg1, respectively. The total concentration of PCBs was low in both estuaries; for samples from the estuary of Urdaibai most of the values were close to the detection limits, except for September 2002, when the total concentration of PCBs was unexpectedly higher in three of the four sampling stations. The same scenario was evident for Hg: the values from the estuary of Bilbao ranged from 0.2 to 7.2 mg kg1, while in Urdaibai values ranged from 0.4 to 1.4 mg kg1. For PAHs, high molecular isomers (Flu, BaA, Chr and BbF) were the most predominant species. DEHP was the most abundant phthalate ester with concentrations always higher than 60% of the total concentration of PEs. PCB-98 showed relatively higher concentrations amongst the PCB congeners. If all values from each estuary were considered, without regard to season, sampling station or grain size, only weak correlations were found. The highest correlations were those between PAHs and Hg (r2 = 0.620) in the estuary of Urdaibai and between TOC and PEs (r2 = 0.60) in the estuary of Bilbao. Considering the potential differences between each estuary, it was decided to focus data analysis on contaminant distribution and possible seasonal effects. In the estuary of Urdaibai (Fig. 2), the highest concentrations of PAHs, PCBs and PEs were found during summertime (September 2002). At this time, there was an unexpected increase in the concentration of PCBs, especially in Arteaga and Murueta, the two lowest points of this estuary (see previous). This pattern was repeated with anthracene concentrations at Arteaga. This may suggest a local contamination episode that partially affected the low channel of the estuary. Fig. 2 shows a rise in concentrations during February 2003, especially in the silty fraction (63–250 lm). The inter-dependence between trace organic contaminant
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Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117 8
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Murueta
Fig. 2. Variation of the total concentrations of (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot along the estuary of Urdaibai during all samplings. Lines showing observed or predicted concentrations that produce biological effects have been indicated as effects range low (ERL), effects range medium (ERM) and apparent effects threshold (AET) (Long et al., 1995).
350
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C PE (mg.Kg-1)
C PAH (mg.Kg-1)
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0 As
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Go
Ka
La
Po
Ud
Zo
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As
Ax
Az
Be
De
Ga
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Ka
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Fig. 3. Total concentrations of (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot in November 2002 and February 2003 in the estuary of Bilbao (Az = Bilbao; De = Deustu; Zo = Zorrotza; Ka = Kadagua; Po = Portu; Ga = Galindo; Be = La Benedicta; La = Lamiako; Go = Gobela; Ud = Udondo; Ax = Axpe and As = Asua). Lines showing observed or predicted concentrations that produce biological effects have been indicated as effects range low (ERL), effects range medium (ERM) and apparent effects threshold (AET) (Long et al., 1995). Results published by the Basque Government in 1997/1998 for certain sampling points considered in this work are also included for comparison in case of Hgtot (Basque Government, 1999).
concentrations, particle size and organic carbon content has been discussed by Horovitz (1991), but in our results no definitive patterns were observed. Indeed, the silty
fraction showed higher concentrations than the clay fraction, even if the total concentrations were normalised to TOC content.
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
Mercury values in Urdaibai ranged from 0.2 to 0.9 mg kg1. Except for Gernika, the highest concentrations were observed in June 2002, while the lowest corresponded to both of the winter periods studied. However, long-term monitoring investigations in this area are required to confirm or reject the observed seasonal behaviour. Arteaga and Murueta showed similar trends, with maximum concentrations in June 2002 and minimum concentrations in December 2001 and February 2003. In the case of Kanala, the variations in concentration with time were not so pronounced. However, at these three sampling points, the total concentration of mercury measured in December 2001 recovered in February 2003 (clay fraction). Gernika exhibited a totally different behaviour. This site is located in an industrialised area and, consequently, it is potentially exposed to spillages; such incidences in the Oka River could explain the unexpectedly high concentrations observed in December 2001 and September 2002. The estuary of Bilbao showed a different pattern (Fig. 3). Since the number of sampling periods was significantly lower, seasonal effects could not be interpreted but the spatial distribution of the contaminants could be discussed. Fig. 3 shows that each contaminant had its own fingerprint in this estuary. In the case of PAHs, the highest concentrations were found in Lamiako, La Benedicta and Udondo, three of the five docks. In the case of PCBs, highest concentrations were observed in Axpe, Galindo, Portu and Udondo; i.e., three docks and one of the tributaries (Galindo). At the latter station, the highest concentrations of PEs were also found, while mercury showed the highest concentrations in Lamiako and Udondo.
40 30 20 10 0 0
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The spatial distribution of the contaminants suggested at least two different scenarios; on the one hand the docks, which are seldom dredged and are close to industrial sewage discharges, and on the other the tributaries, especially Galindo. As shown in a previous study (Landajo et al., 2004), this latter station is immediately downstream of the city sewage treatment plant (which discharges 400,000 m3/day), making this one of the most polluted areas in the estuary. The relationship between concentration and particle size showed a clearer dependence than in Urdaibai Estuary. In the case of PAHs, a correlation coefficient of r2 = 0.752 was obtained (Fig. 4(a)) when all sampling points except for La Benedicta were considered. Regarding PCBs (Fig. 4(b)) and PEs (Fig. 4(c)), correlation coefficients of 0.881 and 0.657 were obtained, respectively when data from Galindo was excluded. Finally, in the case of mercury (Fig. 4(d)), only Asua, Bilbao, Lamiako, Udondo and Zorrotza were analysed, showing a correlation of 0.923. In all the cases, except for mercury, the clay fractions showed concentrations higher than the silty fractions. Only in the case of total mercury and the estuary of Bilbao was a relationship found between concentration and TOC. As indicated in Fig. 5, a relatively strong correlation (r2 = 0.722) was observed when samples with a total mercury content <2 mg kg1 were considered; the higher the TOC value, the higher the mercury concentration that was observed. The Basque Government published data on the total concentration of mercury in sediments collected in the estuary of Bilbao in January 1998 (Basque Government, 1999).
February 2003 63-250 um
y = 1.7699x - 1.9554 R2 = 0.7524
60
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20
15
Fig. 4. Correlations between total concentration and particle size for (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot in sediments collected in the estuary of Bilbao in February 2003.
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Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117 Table 1 PAH isomer average, maximum and minimum ratios
12.0 10.0
Ant/ (Ant + Phe)
BaA/ (BaA + Chr)
Fl/ (Fl + Py)
InP/ (InP + BghiP)
TOC %
8.0 6.0 4.0
Average Max Min
0.26 0.42 0.04
0.50 0.60 0.42
0.53 0.61 0.43
0.56 0.79 0.45
Urdaibai
Average Max Min
0.30 0.75 0.13
0.55 0.68 0.45
0.56 0.60 0.52
0.58 0.65 0.45
R2 = 0.7226
2.0 0.0 0.0
Bilbao
0.5
1.0
1.5
2.0
CHg (mg.g-1)
Fig. 5. Correlations between total mercury concentrations and TOC in the estuary of Bilbao for samples with a content lower than 2 mg kg 1.
Results corresponding to sampling points considered in this work are included for comparison in Fig. 3(d). At many sites, mercury content decreased significantly from 1998 to 2003. Sites at Udondo and Gobela, however, differed from this general trend. Udondo is a closed dock where the Gobela River discharges its waters. Lamiako is very close to these two sampling points, being located in the main channel of the estuary downstream from the Udondo dock. Even though a general, decreasing trend was observed in Lamiako, the site still showed unexpectedly high concentrations of mercury in both November 2002 and February 2003. This could be indicative of a direct input of mercury in the Gobela River which is finally deposited in the Udondo dock and, to a minor extent, in the sediments around the Lamiako area. Based on the following PAH isomer pair ratios, it is possible to suggest the sources of PAH in sediments (Yunker et al., 2002): Ant/(Ant + Phe), BaA/(BaA + Chr), Fl/ (Fl + Py) and InP/(InP + BghiP). Those four ratios were determined for the sediment samples and were compared to previously established ratios from major sources; i.e., environmental samples, petroleum and combustion. Ratios of Ant/(Ant + Phe) <0.10, BaA/(BaA + Chr) <0.20, Fl/ (Fl + Py) <0.40 and InP/(InP + BghiP) <0.20 suggest dominance of petroleum; BaA/(BaA + Chr) 0.20–0.35, Fl/ (Fl + Py) 0.40–0.50 and InP/(InP + BghiP) 0.20–0.50 indicate combustion or petroleum; and Ant/(Ant + Phe) >0.10, BaA/(BaA + Chr) >0.35, Fl/(Fl + Py) >0.50 and InP/(InP + BghiP) >0.50 suggest combustion of coal, grasses and wood. The average, maximum and minimum values from each estuary are summarized in Table 1. The high ratios, together with the narrow range of the values, were consistent with a common source for all the samples in both estuaries: the combustion of petroleum, coal or wood. In the case of Ant/(Ant + Phe), the low value observed in the estuary of Bilbao (0.04) only occurred once at this site (Asua, February 2003) and was considered to be an outlier. In the estuary of Urdaibai, the maximum PAH values during summertime were found at Arteaga and Kanala, while Gernika showed higher values in wintertime. The
Gernika samples were obtained from the centre of the village close to a car park, and contributions from car engines and the domestic heating systems possibly contributed to the high concentrations observed. Arteaga and Kanala are close to the road leading from Gernika to the beaches in the lower part of the estuary. During summertime, this area is extensively utilised for leisure activities, and traffic is much higher than in any other season. This is also a rural area, and domestic fireplaces and controlled burnings possibly contribute to the observed values. In the case of the estuary of Bilbao, the highest concentrations of PAHs were located in three docks: La Benedicta, Lamiako and Udondo. The La Benedicta dock is close to highly populated areas (Sestao and Portugalete) and is also adjacent to a large steel foundry (Aceria Compacta de Bizkaia). Lamiako and Udondo are located near a road from Bilbao to Getxo, which has high traffic flow all over the year except for summertime (July and August). Contaminant concentrations found in both estuaries were compared (Figs. 2 and 3) with the threshold values developed by the US National Oceanic and Atmospheric Administration (NOAA; Long et al., 1995). In the case of total PAHs, certain Urdaibai samples from June 2002 to February 2003 exceeded the ERL and AET values but the ERM value (45 mg kg1) was never exceeded. In the estuary of Bilbao, ERL values were exceeded in November 2002 in all the sampling points, except for the sample taken at the centre of Bilbao. It is noteworthy that the total PAH concentrations in La Benedicta, Lamiako and Udondo in November 2002 were between 3.8 and 7.5 times higher than the ERM values. In terms of individual concentrations of PAHs, almost all compounds exceeded the ERL values in both seasons (November 2002 and February 2003) and in some cases the ERM values were also exceeded. For PCBs, the ERL values were exceeded in all cases. Certain samples (Murueta and Arteaga in September 2002, and some of the sampling points of Bilbao) also exceeded the ERM values, but never the AET threshold (1000 lg kg1). In the case of PEs, the DEHP concentrations found in sediments collected in Bilbao were always higher than the AET threshold value. In a document published by the Spanish Government (1994) concerning the management of dredged materials from harbours and related areas, sediments were classified in different categories considering their metallic and
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
organic contaminant content. For mercury, the following categories were established: Category I, Hg < 1 mg kg1 (no significant chemical effect on biota and direct disposal to the sea); Category II, 1 < Hg < 3 mg kg1 (careful disposal); Category IIIa, 3 < Hg < 24 mg kg1 (soft isolation of sediments); and Category IIIb, Hg >24 mg kg1 (special enclosures for storage). According to this classification, all sediments collected in the estuary of Urdaibai were nonpolluted. Most of the sediments from Bilbao belonged to the first two categories. Samples from Lamiako and Udondo (November 2002 and February 2003), Axpe and Asua (November 2002) and Gobela (February 2003) could be considered as moderately polluted. Acknowledgements This work was supported by the Government of the Basque Country through the ETORTEK projects (IE03-110 and IE04-131) and by the University of the Basque Country through the UNESCO 05/12 project. E. Cortazar is grateful to the University of the Basque Country for his pre-doctoral fellowship. I. Tueros is grateful to the Basque Government for her pre-doctoral fellowship. J. Sanz is grateful to the Basque Government for his post-doctoral fellowship. References Azkona, A., Henkins, S.H., Roberts, H.M.G., 1984. Sources of contamination of the estuary of the river nervio´n, Spain- A case study. Water Sci. Technol. 16, 95–125. Bartolome´, L., Cortazar, E., Raposo, J.C., Usobiaga, A., Zuloaga, O., Etxebarria, N., Ferna´ndez, L.A., 2005. Simultaneous microwaveassisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments. J. Chromatogr. A 1068 (2), 229–236. Basque Government, 1999. La red de vigilancia y control de la calidad de las aguas litorales del Paı´s Vasco: an˜os 1997 y 1998. Departamento de 0025-326X/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2006.05.024
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ordenacio´n del territorio, vivienda y medioambiente. Gobierno VascoEusko Jaurlaritza, Vitoria-Gazteiz. Cearreta, A., Irabien, M.J., Leorri, E., Yusta, I., Croudce, I.W., Cundy, A.B., 2000. Recent anthropogenic impacts on the Bilbao estuary, Northern Spain: Geochemical and microfaunal evidence. Estuar. Coast. Shelf Sci. 50, 571–592. Cortazar, E., Bartolome´, L., Delgado, A., Etxebarria, N., Ferna´ndez, L.A., Usobiaga, A., Zuloaga, O., 2005. Optimisation of microwaveassisted extraction for the determination of nonlylphenols and phthalate esters in sediment samples and comparison with pressurised solvent extractions. Anal. Chim. Acta 534, 247–254. Horovitz, A., 1991. A primer on sediment-trace element chemistry. Lewis Publ., CRC Press, Boca Raton, FL, USA. Irabien, M.J., Velasco, F., 1999. Heavy metals in Oka river sediments (Urdaibai National Reserve, northern Spain): lithogenic and anthropogenic effects. Environ. Geol. 37, 54–63. Landajo, A., Arana, G., de Diego, A., Etxebarria, N., Zuloaga, O., Amouroux, D., 2004. Analysis of heavy metal distribution in superficial estuarine sediments (Estuary of Bilbao, Basque Country) by open-focused microwave-assisted extraction and ICP-OES. Chemosphere 56 (11), 1033–1041. Leong, L.S., Tanner, A., 1999. Comparison of methods for the determination of organic carbon in marine sediment. Mar. Pollut. Bull. 38 (10), 875–879. Long, E.R., MacDonald, D.D., Smith, S.L., Calder, F.D., 1995. Incidence of Adverse Biological Effects within Ranges of Chemical Concentrations in Marine and Estuarine Sediments. Environ. Manage. 19, 81–91. Perkin Elmer, 1994. Flow injection mercury/hydride analysis; Recommended analytical conditions and general information; Part number B959-1820; Publication B3505. Sainz-Salinas, J.I., Frances-Zubillaga, G., Imaz-Eizaguirre, X., 1996. Uso de bioindicadores en la evolucio´n de la contaminacio´n de la rı´a de Bilbao. University of the Basque Country, Publ. Services, Bilbao, Spain. Sanz, J., 2002. PhD Thesis. University of the Basque Country. Bilbao. Spanish Government, 1994. Recomendaciones para la gestio´n del material dragado en puertos espan˜oles, Ministerio Obras Pu´blicas, Transportes y Medio Ambiente, Madrid, Spain. Yunker, M.B., Macdonald, R.W., Vingarzan, R., Mitchell, R.H., Goyette, D., Silvestre, S., 2002. PAHs in the Fraser river basin: a critical appraisal of PAH ratios as indicators of PAH source and composition. Org. Geochem. 33 (4), 489–515.
manuscript is contribution number AED-06-047 of the Atlantic Ecology Division of the United States Environmental Protection Agency, Office of Research and Development, National Health Effects Environmental Research Laboratory. Mention of trade names does not constitute endorsement or recommendation for use. References Abramowicz, D.A., Brennan, M.J., Van Dort, H.M., Gallagher, E.L., 1993. Factors influencing the rate of polychlorinated biphenyl dechlorination in Hudson River sediments. Environ. Sci. Technol. 23, 1125– 1131. Agency for Toxic Substances and Disease Registry (ATSDR), 2000. Atlanta, GA: US Department of Health and Human Services, Public Health Service. Available from:
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Hartmann, P.C., Quinn, J.G., Cairns, R., King, J.W., 2004. Polychlorinated biphenyls in Narragansett Bay surface sediments. Chemosphere 57, 9–20. Hutzinger, O., Safe, S., Zitko, V., 1974. The Chemistry of PCBs. CRC Press, Cleveland, OH, pp. 1–269. Kannan, K., Maruya, K.A., Tanabe, S., 1997. Distribution and characterization of polychlorinated biphenyl congeners in soil and sediments from a superfund site contaminated with Aroclor 1268. Environ. Sci. Technol. 31, 1483–1488. Kannan, K., Nakata, H., Stafford, R., Masson, G.R., Tanabe, S., Giesy, J.P., 1998. Bioaccumulation and toxic potential of extremely hydrophobic polychlorinated biphenyl congeners in biota collected at a Superfund site contaminated with Aroclor 1268. Environ. Sci. Technol. 32, 1214–1221. Ko, F.C., Baker, J.E., 2004. Seasonal and annual loads of hydrophobic organic contaminants from the Susquehanna River Basin to the Chesapeake Bay. Mar. Pollut. Bull. 48, 840–851. Latimer, J.S., 1989. Polychlorinated biphenyls in Narragansett Bay. Ph.D. Dissertation Oceanography University of Rhode Island Narragansett RI, p. 413. Latimer, J.S., Quinn, J.G., 1996. Historical trends and current inputs of hydrophobic organic contaminants in an urban estuary: the sedimentary record. Environ. Sci. Technol. 30, 623–633. Maruya, K.A., Lee, R.F., 1998. Aroclor 1268 and Toxaphene in fish from a Southeastern US Estuary. Environ. Sci. Technol. 32, 1069–1075. Menzie-Cura & Associates, 2000. Muddy Cove ecological risk assessment. Monsanto Chemical Company, 1944. Salesmen’s manuals for Aroclor products. p. 41. Available from:
0025-326X/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2006.05.019
Distribution of trace organic contaminants and total mercury in sediments from the Bilbao and Urdaibai Estuaries (Bay of Biscay) L. Bartolome´, I. Tueros, E. Cortazar, J.C. Raposo, J. Sanz, O. Zuloaga *, A. de Diego, N. Etxebarria, L.A. Ferna´ndez, J.M. Madariaga Kimika Analitikoaren Saila, Euskal Herriko Unibertsitatea, 644 PK, E-48080 Bilbao, Spain
The estuary of Bilbao is one of the most industrialised and populated areas of the Bay of Biscay. Due to its geographic location, as well as its natural richness in mineral resources, the area has been subjected to intense industrial
*
Corresponding author. Tel.: +34 94 601 3269; fax: +34 94 601 3500. E-mail address: [email protected] (O. Zuloaga).
pressure (Azkona et al., 1984). For many years, urban and industrial effluents were discharged into the estuary without further treatment. By the 1970s, water sampling revealed extremely low oxygenation together with high organic matter and heavy metal concentrations (Cearreta et al., 2000; Sainz-Salinas et al., 1996). In 1979, an Integral Plan for the Drainage of the estuary was approved and new environmental protection policies resulted in improved
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wastewater treatment systems. This, together with the closure of several industries, has produced a gradual recovery of the estuarine environment, with a continuing decrease in heavy metal concentrations and an increase in oxygenation. The estuary of Bilbao (Fig. 1(a)) has been considerably constrained from its original state. The tidal channel flows into El Abra Bay, which is 3.5 km in width and 30 m in depth. The tidal zone of the Ibaizabal River forms the estuary, although four tributaries (Kadagua, Asua, Galindo and Gobela) also discharge in the estuary. There are docks and secondary channels (the channel of Deustu and the docks of Axpe, Udondo, La Benedicta, Lamiako and Portu) in the upper zone of the estuary. This area was the most affected by urban and industrial wastes (Cearreta et al., 2000). The estuary of Urdaibai and its surroundings have been a reserve since 1984, and are located in a rural environment about 50 km east from the Ibaizabal valley. The Urdaibai region (Fig. 1(b)) is characterised by the basin of the Oka River, and by some shorter rivers, including the Golako, Mape, Artike and Laga. The estuary, some 13 km long and 500 m wide, is located in relatively close proximity to
several industries (metallurgic, shipyards, dyes, cutlery manufacture) located in the surroundings of Gernika (population 20,000) upstream the Oka River (Irabien and Velasco, 1999). This paper reports (1) the spatial and seasonal variation of Hg, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and phthalate esters (PEs) in both estuaries; (2) the association of total concentration of these contaminants with particle size and TOC; and (3) the origin of these contaminants. Sediments were collected during five different sampling periods (December 2001, June 2002, September 2002, November 2002 and February 2003) at four sites in the estuary of Urdaibai and during two sampling periods (November 2002 and February 2003) at 12 points in the estuary of Bilbao. Fig. 1 shows the sampling points in both estuaries. Surficial sediment samples were collected by hand, stored in pre-cleaned glass flasks and transported to the laboratory in cool boxes. Once in the laboratory, the sediments were frozen and lyophilised at low temperatures (46/52 C) and pressures (0.17/0.22 mbar) in a Cryodos-50 freeze-drier (Telstar, Spain). The freeze-dried samples were treated in
Fig. 1. Sampling points in the estuaries of (a) Bilbao (1 = Bilbao; 2 = Deustu; 3 = Zorrotza; 4 = Kadagua; 5 = Portu; 6 = Galindo; 7 = La Benedicta; 8 = Lamiako; 9 = Gobela; 10 = Udondo; 11 = Axpe and 12 = Asua) and (b) Urdaibai (A = Kanala; B = Arteaga; D = Gernika and E = Murueta).
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
two different ways. Samples collected before February 2003 were ground in a ball grinder (Fristch Pulverisette 6, Germany), sieved (250 lm), stored in glass vials and kept at 4 C until analysis. Sediments from February 2003 were freeze-dried and then sieved at three different particles sizes: (i) sand, >250 lm; (ii) silt, 250 lm and (iii) clay, <63 lm. The smallest two fractions were stored at 4 C until analysis. The sand, silt and clay contents of these sediments were estimated by weighing the different fractions using an analytical balance. The sediments were further characterised by measuring total organic carbon (TOC) by the Walkley–Black titration method (Leong and Tanner, 1999). For the analysis of organic compounds, 1.0 g of dry sediment was accurately weighed and submitted to microwave-assisted extraction in 15 ml of acetone at 21 psi for 15 min and at 80% of microwave power in a MDS-2000 microwave (CEM, Matthews, NC, USA), after 25 ll of a mixture of acenaphthene-d10, chrysene-d12 and phenanthrene-d10 at 20 lg ml1 in acetone and 25 ll of a mixture of dibenzyl phthalate, diphenyl isophthalate and diphenyl phthalate at 20 lg ml1 in acetone were added as internal standards. The extract was concentrated under a gentle stream of nitrogen and loaded onto a 1 g Florisil cartridge (Supelco, Walton-on-Thames, UK) for further clean-up of the sample. PAHs and PCBs were eluted in 12 ml of a (4:1) n-hexane:toluene mixture and PEs in 5 ml of ethyl acetate. The eluates were concentrated to dryness, re-dissolved in 500 ll of iso-octane and kept in the dark at 18 C until analysis (Bartolome´ et al., 2005). The extracts were analysed in a 6890 N Agilent gas chromatograph coupled to a 5973 N Agilent mass spectrometer (Agilent Technologies Inc., Avondale, PA, USA) with a 7683 Agilent autosampler. 2 ll of sample were injected in splitless mode at 270 C into a 30 m · 0.25 mm · 0.25 lm HP-5 capillary column (Agilent Technologies Inc.). The method summarised above was validated in our laboratories using the certified reference marine sediment NIST 1944 (Gaithersburg, MD, USA) in the case of PAHs and PCBs and by comparison of different extraction techniques for phthalate esters (Cortazar et al., 2005). Regarding total mercury, 0.5 g of sediment were weighed, transferred into borosilicate vessels and digested in 20 ml of HCl (5 mol l1) in the microwave cavity of a focused Microdigest 3.6 microwave oven (Prolabo, France) for 12 min at 63% of microwave power (Sanz, 2002). Once the extraction period was completed, the extract was centrifuged, diluted to 50 ml and analysed by quartz furnace atomic absorption spectrometry (QFAAS; 4110 ZL spectrometer, Perkin Elmer) after hydride generation (HG) of the sample in a FIA system (FIAS 400, Perkin Elmer). The analysis was performed using the standard conditions recommended by the manufacturer (Perkin Elmer, 1994). The analysis of mercury was validated using NIST 1944, PACS-1 and CRM-580 materials, with satisfactory results (Sanz, 2002). Blank samples were processed in the same way as sediment samples in order to estimate the detection limits (1–
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22 lg kg1 for PAHs, 1–3 lg kg1 for PCBs, 1–43 lg kg1 for PEs and 0.6 lg kg1 for total mercury). A number of sediment samples were analysed in duplicate in order to calculate the repeatability of the method. The relative standard deviations (RSD) estimated in this way were lower than 20% for all the analytes studied, except for bis (2-ethyl-hexyl) phthalate (DEHP) with a RSD value of 40%. The results obtained for the total concentrations of PAHs, PCBs, PEs and Hg are summarised in Figs. 2 and 3 for the estuaries of Urdaibai and Bilbao respectively. In order to calculate the total concentration of each group of contaminant, the concentration of each congener or isomer was taken into account, including the values below the detection limits (where half of the detection limit was used). The estuary of Bilbao showed higher contaminant concentrations than Urdaibai. The organic matter content in the former ranged from 1.8% to 9.9%, while in the estuary of Urdaibai the values were between 1.6% and 5.4%. For PAHs and PEs, the differences were more significant. While the contents of PAHs and PEs ranged from 0.7 to 300 mg kg1 and from 0.8 to 140 mg kg1 respectively in Bilbao, the estuary of Urdaibai showed values between 0.7–7.2 mg kg1 and 0.05–14 mg kg1, respectively. The total concentration of PCBs was low in both estuaries; for samples from the estuary of Urdaibai most of the values were close to the detection limits, except for September 2002, when the total concentration of PCBs was unexpectedly higher in three of the four sampling stations. The same scenario was evident for Hg: the values from the estuary of Bilbao ranged from 0.2 to 7.2 mg kg1, while in Urdaibai values ranged from 0.4 to 1.4 mg kg1. For PAHs, high molecular isomers (Flu, BaA, Chr and BbF) were the most predominant species. DEHP was the most abundant phthalate ester with concentrations always higher than 60% of the total concentration of PEs. PCB-98 showed relatively higher concentrations amongst the PCB congeners. If all values from each estuary were considered, without regard to season, sampling station or grain size, only weak correlations were found. The highest correlations were those between PAHs and Hg (r2 = 0.620) in the estuary of Urdaibai and between TOC and PEs (r2 = 0.60) in the estuary of Bilbao. Considering the potential differences between each estuary, it was decided to focus data analysis on contaminant distribution and possible seasonal effects. In the estuary of Urdaibai (Fig. 2), the highest concentrations of PAHs, PCBs and PEs were found during summertime (September 2002). At this time, there was an unexpected increase in the concentration of PCBs, especially in Arteaga and Murueta, the two lowest points of this estuary (see previous). This pattern was repeated with anthracene concentrations at Arteaga. This may suggest a local contamination episode that partially affected the low channel of the estuary. Fig. 2 shows a rise in concentrations during February 2003, especially in the silty fraction (63–250 lm). The inter-dependence between trace organic contaminant
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Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117 8
nov-02 feb-03 <63 um
5
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1.4 1.2 C Hgtot (mg.Kg-1)
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300 250 200
feb-03 63-250 um ER-L
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dec-01 jun-02 sep-02 nov-02 feb-03 <63 um ER-L ER-M AET
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C PCB (µg.Kg-1)
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0
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sep-02
12 C PE (mg.Kg-1)
C PAH (mg.Kg-1)
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1 0.8 0.6
100
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50
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0
0
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Arteaga
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(d)
Murueta
Kanala
Arteaga
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Murueta
Fig. 2. Variation of the total concentrations of (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot along the estuary of Urdaibai during all samplings. Lines showing observed or predicted concentrations that produce biological effects have been indicated as effects range low (ERL), effects range medium (ERM) and apparent effects threshold (AET) (Long et al., 1995).
350
160
feb-03 <63 um
140
feb-03 63-250 um
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C PE (mg.Kg-1)
C PAH (mg.Kg-1)
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0 As
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Go
Ka
La
Po
Ud
Zo
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As
Ax
Az
Be
De
Ga
Go
Ka
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Po
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Zo
Fig. 3. Total concentrations of (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot in November 2002 and February 2003 in the estuary of Bilbao (Az = Bilbao; De = Deustu; Zo = Zorrotza; Ka = Kadagua; Po = Portu; Ga = Galindo; Be = La Benedicta; La = Lamiako; Go = Gobela; Ud = Udondo; Ax = Axpe and As = Asua). Lines showing observed or predicted concentrations that produce biological effects have been indicated as effects range low (ERL), effects range medium (ERM) and apparent effects threshold (AET) (Long et al., 1995). Results published by the Basque Government in 1997/1998 for certain sampling points considered in this work are also included for comparison in case of Hgtot (Basque Government, 1999).
concentrations, particle size and organic carbon content has been discussed by Horovitz (1991), but in our results no definitive patterns were observed. Indeed, the silty
fraction showed higher concentrations than the clay fraction, even if the total concentrations were normalised to TOC content.
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
Mercury values in Urdaibai ranged from 0.2 to 0.9 mg kg1. Except for Gernika, the highest concentrations were observed in June 2002, while the lowest corresponded to both of the winter periods studied. However, long-term monitoring investigations in this area are required to confirm or reject the observed seasonal behaviour. Arteaga and Murueta showed similar trends, with maximum concentrations in June 2002 and minimum concentrations in December 2001 and February 2003. In the case of Kanala, the variations in concentration with time were not so pronounced. However, at these three sampling points, the total concentration of mercury measured in December 2001 recovered in February 2003 (clay fraction). Gernika exhibited a totally different behaviour. This site is located in an industrialised area and, consequently, it is potentially exposed to spillages; such incidences in the Oka River could explain the unexpectedly high concentrations observed in December 2001 and September 2002. The estuary of Bilbao showed a different pattern (Fig. 3). Since the number of sampling periods was significantly lower, seasonal effects could not be interpreted but the spatial distribution of the contaminants could be discussed. Fig. 3 shows that each contaminant had its own fingerprint in this estuary. In the case of PAHs, the highest concentrations were found in Lamiako, La Benedicta and Udondo, three of the five docks. In the case of PCBs, highest concentrations were observed in Axpe, Galindo, Portu and Udondo; i.e., three docks and one of the tributaries (Galindo). At the latter station, the highest concentrations of PEs were also found, while mercury showed the highest concentrations in Lamiako and Udondo.
40 30 20 10 0 0
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-10
The spatial distribution of the contaminants suggested at least two different scenarios; on the one hand the docks, which are seldom dredged and are close to industrial sewage discharges, and on the other the tributaries, especially Galindo. As shown in a previous study (Landajo et al., 2004), this latter station is immediately downstream of the city sewage treatment plant (which discharges 400,000 m3/day), making this one of the most polluted areas in the estuary. The relationship between concentration and particle size showed a clearer dependence than in Urdaibai Estuary. In the case of PAHs, a correlation coefficient of r2 = 0.752 was obtained (Fig. 4(a)) when all sampling points except for La Benedicta were considered. Regarding PCBs (Fig. 4(b)) and PEs (Fig. 4(c)), correlation coefficients of 0.881 and 0.657 were obtained, respectively when data from Galindo was excluded. Finally, in the case of mercury (Fig. 4(d)), only Asua, Bilbao, Lamiako, Udondo and Zorrotza were analysed, showing a correlation of 0.923. In all the cases, except for mercury, the clay fractions showed concentrations higher than the silty fractions. Only in the case of total mercury and the estuary of Bilbao was a relationship found between concentration and TOC. As indicated in Fig. 5, a relatively strong correlation (r2 = 0.722) was observed when samples with a total mercury content <2 mg kg1 were considered; the higher the TOC value, the higher the mercury concentration that was observed. The Basque Government published data on the total concentration of mercury in sediments collected in the estuary of Bilbao in January 1998 (Basque Government, 1999).
February 2003 63-250 um
y = 1.7699x - 1.9554 R2 = 0.7524
60
1115
20
15
Fig. 4. Correlations between total concentration and particle size for (a) PAHs, (b) PCBs, (c) PEs and (d) Hgtot in sediments collected in the estuary of Bilbao in February 2003.
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Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117 Table 1 PAH isomer average, maximum and minimum ratios
12.0 10.0
Ant/ (Ant + Phe)
BaA/ (BaA + Chr)
Fl/ (Fl + Py)
InP/ (InP + BghiP)
TOC %
8.0 6.0 4.0
Average Max Min
0.26 0.42 0.04
0.50 0.60 0.42
0.53 0.61 0.43
0.56 0.79 0.45
Urdaibai
Average Max Min
0.30 0.75 0.13
0.55 0.68 0.45
0.56 0.60 0.52
0.58 0.65 0.45
R2 = 0.7226
2.0 0.0 0.0
Bilbao
0.5
1.0
1.5
2.0
CHg (mg.g-1)
Fig. 5. Correlations between total mercury concentrations and TOC in the estuary of Bilbao for samples with a content lower than 2 mg kg 1.
Results corresponding to sampling points considered in this work are included for comparison in Fig. 3(d). At many sites, mercury content decreased significantly from 1998 to 2003. Sites at Udondo and Gobela, however, differed from this general trend. Udondo is a closed dock where the Gobela River discharges its waters. Lamiako is very close to these two sampling points, being located in the main channel of the estuary downstream from the Udondo dock. Even though a general, decreasing trend was observed in Lamiako, the site still showed unexpectedly high concentrations of mercury in both November 2002 and February 2003. This could be indicative of a direct input of mercury in the Gobela River which is finally deposited in the Udondo dock and, to a minor extent, in the sediments around the Lamiako area. Based on the following PAH isomer pair ratios, it is possible to suggest the sources of PAH in sediments (Yunker et al., 2002): Ant/(Ant + Phe), BaA/(BaA + Chr), Fl/ (Fl + Py) and InP/(InP + BghiP). Those four ratios were determined for the sediment samples and were compared to previously established ratios from major sources; i.e., environmental samples, petroleum and combustion. Ratios of Ant/(Ant + Phe) <0.10, BaA/(BaA + Chr) <0.20, Fl/ (Fl + Py) <0.40 and InP/(InP + BghiP) <0.20 suggest dominance of petroleum; BaA/(BaA + Chr) 0.20–0.35, Fl/ (Fl + Py) 0.40–0.50 and InP/(InP + BghiP) 0.20–0.50 indicate combustion or petroleum; and Ant/(Ant + Phe) >0.10, BaA/(BaA + Chr) >0.35, Fl/(Fl + Py) >0.50 and InP/(InP + BghiP) >0.50 suggest combustion of coal, grasses and wood. The average, maximum and minimum values from each estuary are summarized in Table 1. The high ratios, together with the narrow range of the values, were consistent with a common source for all the samples in both estuaries: the combustion of petroleum, coal or wood. In the case of Ant/(Ant + Phe), the low value observed in the estuary of Bilbao (0.04) only occurred once at this site (Asua, February 2003) and was considered to be an outlier. In the estuary of Urdaibai, the maximum PAH values during summertime were found at Arteaga and Kanala, while Gernika showed higher values in wintertime. The
Gernika samples were obtained from the centre of the village close to a car park, and contributions from car engines and the domestic heating systems possibly contributed to the high concentrations observed. Arteaga and Kanala are close to the road leading from Gernika to the beaches in the lower part of the estuary. During summertime, this area is extensively utilised for leisure activities, and traffic is much higher than in any other season. This is also a rural area, and domestic fireplaces and controlled burnings possibly contribute to the observed values. In the case of the estuary of Bilbao, the highest concentrations of PAHs were located in three docks: La Benedicta, Lamiako and Udondo. The La Benedicta dock is close to highly populated areas (Sestao and Portugalete) and is also adjacent to a large steel foundry (Aceria Compacta de Bizkaia). Lamiako and Udondo are located near a road from Bilbao to Getxo, which has high traffic flow all over the year except for summertime (July and August). Contaminant concentrations found in both estuaries were compared (Figs. 2 and 3) with the threshold values developed by the US National Oceanic and Atmospheric Administration (NOAA; Long et al., 1995). In the case of total PAHs, certain Urdaibai samples from June 2002 to February 2003 exceeded the ERL and AET values but the ERM value (45 mg kg1) was never exceeded. In the estuary of Bilbao, ERL values were exceeded in November 2002 in all the sampling points, except for the sample taken at the centre of Bilbao. It is noteworthy that the total PAH concentrations in La Benedicta, Lamiako and Udondo in November 2002 were between 3.8 and 7.5 times higher than the ERM values. In terms of individual concentrations of PAHs, almost all compounds exceeded the ERL values in both seasons (November 2002 and February 2003) and in some cases the ERM values were also exceeded. For PCBs, the ERL values were exceeded in all cases. Certain samples (Murueta and Arteaga in September 2002, and some of the sampling points of Bilbao) also exceeded the ERM values, but never the AET threshold (1000 lg kg1). In the case of PEs, the DEHP concentrations found in sediments collected in Bilbao were always higher than the AET threshold value. In a document published by the Spanish Government (1994) concerning the management of dredged materials from harbours and related areas, sediments were classified in different categories considering their metallic and
Baseline / Marine Pollution Bulletin 52 (2006) 1090–1117
organic contaminant content. For mercury, the following categories were established: Category I, Hg < 1 mg kg1 (no significant chemical effect on biota and direct disposal to the sea); Category II, 1 < Hg < 3 mg kg1 (careful disposal); Category IIIa, 3 < Hg < 24 mg kg1 (soft isolation of sediments); and Category IIIb, Hg >24 mg kg1 (special enclosures for storage). According to this classification, all sediments collected in the estuary of Urdaibai were nonpolluted. Most of the sediments from Bilbao belonged to the first two categories. Samples from Lamiako and Udondo (November 2002 and February 2003), Axpe and Asua (November 2002) and Gobela (February 2003) could be considered as moderately polluted. Acknowledgements This work was supported by the Government of the Basque Country through the ETORTEK projects (IE03-110 and IE04-131) and by the University of the Basque Country through the UNESCO 05/12 project. E. Cortazar is grateful to the University of the Basque Country for his pre-doctoral fellowship. I. Tueros is grateful to the Basque Government for her pre-doctoral fellowship. J. Sanz is grateful to the Basque Government for his post-doctoral fellowship. References Azkona, A., Henkins, S.H., Roberts, H.M.G., 1984. Sources of contamination of the estuary of the river nervio´n, Spain- A case study. Water Sci. Technol. 16, 95–125. Bartolome´, L., Cortazar, E., Raposo, J.C., Usobiaga, A., Zuloaga, O., Etxebarria, N., Ferna´ndez, L.A., 2005. Simultaneous microwaveassisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments. J. Chromatogr. A 1068 (2), 229–236. Basque Government, 1999. La red de vigilancia y control de la calidad de las aguas litorales del Paı´s Vasco: an˜os 1997 y 1998. Departamento de 0025-326X/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2006.05.024
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