Water, Air, and Soil Pollution

, 204:271

Changes of Heavy Metal and PCB Contents in Surficial Sediments of the Barcelona Harbour after the Opening of a New Entrance

Authors

  • Oriol Gibert
    • Environmental Technology Area, CTM, Chemical Engineering Dep.UPC
  • Xavier Martínez-Lladó
    • Environmental Technology Area, CTM, Chemical Engineering Dep.UPC
  • Vicens Martí
    • Environmental Technology Area, CTM, Chemical Engineering Dep.UPC
    • Environmental Chemistry DepartmentIDAEA-CSIC
  • Javier Romo
    • Departament de Seguretat Industrial i Medi AmbientAutoritat Portuària de Barcelona
  • Josep M. Bayona
    • Environmental Chemistry DepartmentIDAEA-CSIC
  • Joan de Pablo
    • Environmental Technology Area, CTM, Chemical Engineering Dep.UPC
Article

DOI: 10.1007/s11270-009-0044-6

Cite this article as:
Gibert, O., Martínez-Lladó, X., Martí, V. et al. Water Air Soil Pollut (2009) 204: 271. doi:10.1007/s11270-009-0044-6

Abstract

The Barcelona harbour is one of the biggest and most important in commercial and passenger traffic in the Mediterranean Sea. In 2003, construction works for the enlargement of the port were carried out with the opening of a new entrance for large boats in the northern area. Following the opening of this new mouth, the redistribution of heavy metals (Hg, Cd, Pb, Cu, Zn, Ni and Cr), As and polychlorinated biphenyls (PCBs) was investigated to discuss their origin and to evaluate the environmental implications. A previous study of the sediments provided a first picture of high levels of heavy metals and PCBs in the innermost harbour (Port Vell). Then, the opening of the northern mouth led to a remarkable decline in the contaminant concentrations and to an improvement of the sediment quality. During the period 2002–2005, the percentage of concentration decreases in Port Vell for Hg, Pb and PCB (from 20% to 34%), for Zn and Cd (from 10% to 15%) and for the remaining metals with values lesser than 10%. This general decline was probably due to a more efficient water flushing between the original and the new northern entrance. Concentrations of target contaminants were also compared against sediment quality guidelines to assess the ecotoxicological significance of sedimentary contaminants on the benthic communities.

Keywords

Surficial sedimentsPollutionHeavy metalsPCBsBarcelona harbour

1 Introduction

Harbour environments are permanently subjected to anthropogenic stressors that result in the incorporation of many contaminants into the harbour ecosystems. Bottom sediments are usually considered the final repository of a wide range of contaminants, deserving a special consideration in marine pollution studies (Birch and Taylor 1999; Galanopoulou et al. 2005).

Sediments in harbours can be contaminated by hundreds of individual compounds. The occurrence of polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT) in sediments of Barcelona harbour and their impact on benthic communities were evaluated in a previous study (Martínez-Lladó et al. 2007). That study revealed that sediments were low to moderately contaminated by PAHs but highly to extremely highly contaminated by TBT, which could represent a serious environmental threat for the benthic community in the Barcelona harbour. However, other persistent and potentially harmful contaminants like heavy metals, arsenic and polychlorinated biphenyls (PCBs) have been reported to exert adverse effects on the benthic fauna (Salas et al. 2004; Borja et al. 2003; Solis-Weiss et al. 2004; van den Hurk et al. 1997) and must also be taken into consideration.

Heavy metals and arsenic are acknowledged to be serious pollutants in the aquatic ecosystems above a certain threshold because of their persistence, toxicity, and bioaccumulation (Islam and Tanaka 2004; Solis-Weiss et al. 2004; Sprovieri et al. 2007). Although natural sources cannot be neglected, they are by-products of many industrial processes and are introduced into the marine environment through industrial discharges, domestic sewage, and atmospheric deposition (Guerra-García and García-Gómez 2005; Kelderman et al. 2000). Once introduced into the marine environment, heavy metals are related to interferences of metabolic processes, suppression of the immune system and loss of cellular integrity and lesions of a number of organs in marine mammals (Islam and Tanaka 2004 and references therein).

PCBs are persistent organic pollutants of synthetic origin and highly lipophilic depending on the chlorination degree. Due to their high toxicity, persistence, low solubility in water and hydrophobic nature, PCBs are mainly accumulated in the food chain (Galanopoulou et al. 2005; Islam and Tanaka 2004) or absorbed in sediments (Kang et al. 2000). Despite a 1970s ban on the use of PCBs in many countries, their presence is linked to a wide range of anthropogenic activities, mainly from the electrical transformer industry, electrical equipment and other industrial applications (Barakat et al. 2002; Wurl and Obbard 2005, Islam and Tanaka 2004). Similar to heavy metals, the introduction of PCBs is mainly via sewage, industrial discharges and atmospheric deposition (Galanopoulou et al. 2005). Once in the marine compartment, they tend to adsorb onto sediment particulates or bioaccumulate into lipids in aquatic biota (Hartmann et al. 2004). Their toxicological impacts have been observed at relatively low concentrations and include reproductive and immunological abnormalities and endocrine disruption in aquatic populations and probable human carcinogenicity (Hartmann et al. 2004; Islam and Tanaka 2004).

The aim of the present study was to report on the concentrations of heavy metals: Hg, Cd, Pb, Cu, Zn, Ni and Cr, As and PCBs in sediments throughout the Barcelona harbour, Catalonia (Spain), and to assess their potential ecological impact on the benthic communities inhabiting the harbour sediments. Thus, surface sediments were analysed from representative locations of the harbour during three campaigns over the 2002–2005 period. During this period, the opening of a second entrance in the north area of the harbour provides an ideal chance to report changes in the final concentration of target contaminants. Hence, comparison with sediment quality guidelines (SQGs), data from other harbours and temporal trends was also performed.

2 Methods

2.1 Barcelona Harbour Description

The Barcelona harbour (41° 20′ N, 2°10′ E) is one of the most important harbours in the western Mediterranean Sea. It is heavily trafficked with large vessels (>9,500 arrivals per year), ferries (2.5 million passengers per year) and tankers (>46 million tons per year; data referred to 2006), with a progressive annual increase in the activity (http://www.apb.es/). The outer concrete breakwater stretches about 4 km, encompassing a total area of 374 ha (Fig. 1). The harbour is divided into two main sections: the civil port (Port Vell), which is located in the inner core and holds yachting and recreational boating activities, and the industrial harbour, which is used for the loading and unloading of marine cargoes and the handling shipping (Fig. 1). The harbour main entrance (southern mouth) lies between the Flammables Pier and the outer breakwater with a horizontal clearance of approximately 370 m. The harbour had been affected by stormwater runoff and combined sewer overflows (CSO) from the metropolitan area of Barcelona (1.6 million inhabitants). These discharges, together with the intense shipping activities, made Barcelona harbour a polluted environment and prompted environmental restoration activities (Martínez-Lladó et al. 2007; Díez et al. 2002, 2006).
https://static-content.springer.com/image/art%3A10.1007%2Fs11270-009-0044-6/MediaObjects/11270_2009_44_Fig1_HTML.gif
Fig. 1

Map of the Barcelona harbour with sampling stations for the campaigns reported in this study. Port Vell is the section included in the insert

These actions included the implementation of measures in order to prevent the direct harbour inflow from stormwater runoff and CSO in 2000, and the opening of a new entrance mouth (northern mouth) at the end of 2003, close to the Port Vell area. This strategic plan was performed to increase the infrastructures of the port, avoid the transit of some ships through industrial harbour and hopefully contribute to the renewal of water in Port Vell. Accordingly, a preliminary simulation study of an idealised Mediterranean harbour with one or two entrances (Sánchez-Arcilla et al. 2002) showed, as expected, an increase in seawater circulation for the second-harbour entrance. In addition, relevant data on hydrodynamics of Barcelona harbour, as a tool to solve certain water quality problems, have been recently presented (Caceres et al. 2008). The main water current follows north–south circulation (e.g. the water enters the harbour through the north entrance, runs along the channel parallel to the main dike and leaves the harbour through the south entrance). This new mouth has a clearance of 145 m and has significantly changed the previous water flushing since the water residence time in the transect from stations S1 to S12 decreased from 40 days in 2002 (Sánchez-Arcilla et al. 2002) to 11 days in 2004 (Barrero 2004).

2.2 Sediment Sampling and Analysis

Sediments along the harbour area were collected for analysis of granulometry, organic matter content, a suite of seven heavy metals Hg, Cd, Pb, Cu, Zn, Ni and Cr, As and PCBs (seven congeners) in July 2002 (before the opening of the northern mouth) and December 2003 and December 2005 (after the opening of the northern mouth). The position of the sampling stations is summarised in Fig. 1 and Table 1 (mainly, points C# have been studied in 2002 and are located in Port Vell; S# have been studied in 2003 and are distributed along the whole harbour and T# have been studied in 2005). A global positioning system was used to record each location accurately.
Table 1

Physicochemical characterisation of sediments at sampling stations, comprising granulometry (%), organic matter content (TOC, g kg−1 dw), heavy metals and As (g kg−1 dw) and PCBs (μg kg−1 dw)

 

Campaign 2002

Campaign 2003

Campaign 2005

Inner harbour (Port Vell)

Port Vell

Outer harbour

Port Vell

Outer harbour

C-1

C-2

C-3

C-4

C-5

C-6

C-7

C-8

C-9

C-10

C-11

C-12

C-13

C-14

C-15

C-1

C-7

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

S-9

S-10

S-11

S-12

C-1

T-1

T-2

S-1

T-3

S-9

S-11

S-12

Gravel (>2 mm)

8

5

10

23

17

3

7

2

1

10

12

20

3

14

4

1

2

2

20

4

1

<1

<1

<1

<1

nd

nd

2

1.4

2

<1

9

1

1

<1

<1

2

Sand (63 μm–2mm)

39

41

54

45

41

67

46

78

22

62

32

22

64

30

61

40

87

71

66

42

36

37

59

34

39

nd

nd

29

65

42

62

46

80

52

98

44

50

Mud (<63 μm)

53

53

37

32

42

29

47

20

77

28

56

58

38

56

36

59

11

27

14

54

63

63

41

65

61

nd

nd

69

34

56

37

44

19

47

<1

56

48

TOC

61

42

28

25

26

18

18

15

53

22

53

73

26

36

20

61

10

15

8

17

26

23

17

24

24

nd

nd

29

11

50

18

40

12

19

3

20

20

Hg

4.8

4.4

5.3

4.4

3.7

4.0

0.9

6.0

4.9

8.0

6.9

9.0

19.8

4.3

4.9

4.1

3.3

3.8

2.4

1.2

1.2

0.9

1.1

0.9

1.1

1.2

1.1

1.6

1.0

3.9

3.0

7.7

3.3

1.0

1.1

1.2

0.9

Cd

3.8

1.9

1.7

1.2

0.9

0.7

0.3

1.3

2.0

2.0

2.4

2.1

2.2

1.2

2.8

2.9

0.4

0.7

0.6

0.6

0.7

0.6

0.8

1.0

0.8

1.5

1.8

1.2

0.9

1.8

0.6

2.1

1.1

0.7

0.9

0.9

1.0

Pb

571

388

454

350

288

231

52

305

388

555

493

459

696

356

382

455

201

228

155

92

91

79

79

78

72

104

117

131

87

340

158

431

151

71

67

78

83

Cu

534

384

417

371

359

312

55

366

621

478

543

676

784

447

360

601

228

219

137

102

116

72

79

76

82

160

162

96

75

539

220

664

175

69

78

69

64

Zn

1,116

694

704

569

512

424

106

452

766

717

859

898

927

770

711

1,165

332

369

274

220

259

204

212

217

216

424

474

305

254

715

270

834

290

172

174

186

208

As

31

32

39

30

27

27

19

28

33

39

35

35

47

28

28

29

28

30

27

19

19

17

18

17

17

21

20

19

17

28

23

36

26

11

20

20

18

Ni

46

35

38

31

29

28

25

28

38

41

47

40

41

33

45

32

20

22

21

22

23

21

20

18

20

29

31

24

19

39

27

42

28

32

30

30

30

Cr

97

99

105

89

103

78

32

74

109

107

101

70

73

74

124

94

63

68

70

60

65

54

78

72

82

104

96

106

105

105

76

117

73

45

64

64

69

Σ7 PCB

217

319

309

239

181

120

14

185

278

502

445

915

1,829

297

220

273

137

137

126

85

92

107

91

72

75

96

49

233

136

428

134

69

0.6

54

47

Estimated by loss of ignition

nd not determined

Surface sediments were sampled using a Van Veen grab (0.025 m2) and stored in air-tight jars at 4°C and in darkness prior to analysis. The analyses were carried out according to well-established procedures outlined by the “Recommendations for the management of dredged material in the ports of Spain” and described elsewhere (CEDEX 1994; Casado-Martínez et al. 2006). The dry weight fraction was determined by weight loss at 105°C and granulometry was determined by passing homogenised samples through 63- and 2,000-μm nylon mesh sieves according to UNE 103-101/95. Total organic carbon (TOC) was determined gravimetrically by ashing to 550°C homogenised subsamples of the fraction <2 mm for 6 h and using TOC (g·kg−1) = 0.35 × LOI (g·kg−1) where LOI is the loss on ignition (CEDEX 1994).

For heavy metal analysis, subsamples of the fine fraction (<63 μm) were dried at 55°C for 24 h and then powdered with a mortar. Subsamples (0.5 g) were acid-digested (HNO3 and aqua regia in a proportion of 1:3) in a microwave using Teflon beakers in a pressurised system following a standard operating procedure. The supernatants were collected and stored in polyethylene vials at 4°C until analysis. Heavy metals such as Zn, Ni, Cr, Cu, Pb and Cd were analysed by atomic absorption spectrophotometry (AAS) using air-acetylene flame or graphite furnace instrumentation; Hg was analysed by cold vapour atomic absorption spectroscopy after reduction with SnCl2 and As by hydride generation coupled to AAS using NaBH4 as a reductant.

In order to perform the PCB determination, freeze-dried sediment samples (sieved at 63 μm) were extracted using sonication with cyclohexane and dichloromethane, followed by reduction in volume and purification through silica gel. Seven PCB congeners (#28, #52, #101, #118, #138, #153, #180) were then identified and quantified by gas chromatography coupled to an electron capture detection, following US Environmental Protection Agency Method 8080. Detection limits for the individual PCBs compounds in the sediment samples were 0.8 μg kg−1 (on a dry weight [dw] basis). Quantification of the PCBs is reported in this study as summed total concentration of the seven individual congeners.

All the concentrations reported in this work are presented on a dw basis.

3 Results and Discussion

Table 1 summarises the results of the physicochemical analysis (granulometry, organic matter content, heavy metals, As and PCBs) for surface sediments collected throughout the Barcelona harbour for the campaigns carried out in 2002, 2003 and 2005.

3.1 Granulometry and Total Organic Matter Content

The percentage of muds (<63 μm) determined in this study ranged from <1% to 77% (with an average of 42%), while the percentages of sands and gravels ranged between 22% and 98% (average 52%) and between <1% and 20% (average 5%), respectively. The proportions of mud and sand varied irregularly across the harbour and no trends could be distinguished. Considering the elevated percentages of fine particles (<63 μm), sediments throughout the Barcelona harbour could be typified as muddy or silty sediments (Gray 1996; Stronkhorst and van Hattum 2003). Organic matter distribution also showed an irregular distribution, with peak values of >60 g kg−1 at stations C-1 and C-12 and an average of 27 g kg−1.

3.2 Heavy Metals and As

For the campaign carried out in 2002, on an individual metal basis and among the metals analysed, the sedimentary levels of Zn, Cu and Pb (and to a lesser extent Cr) were the highest, with average concentrations in the inner port of 682, 447, 398 and 88 mg kg−1, respectively. Enrichment of marine sediments with Zn, Cu and Pb is common and was also found in a number of harbours and city channel sediments (Guerra-García and García-Gómez 2005; Kelderman et al. 2000; Birch and Taylor 1999). The remaining metals presented much lower concentrations, with average concentrations in the order of Ni (36 mg kg−1) > As (32 mg kg−1) > Hg (6 mg kg−1) > Cd (2 mg kg−1). These high values are not surprising since Port Vell suffers intense boat traffic and continuous moorings of recreational boats. The confinement of these stations in semi-enclosed areas with limited water exchange clearly contributed to the accumulation of contaminants at these locations.

Concerning the spatial distribution in Port Vell, stations C-1 and C-13 appeared to be hot spot stations and, into a lesser extent, C-11, C-12 and C-15. These high values could be attributed to sampling sites with a lesser seawater flushing and near fuelling stations, boat repairing and painting facilities, which can lead to an increase of heavy metals deposited from fuel and ship paint (Fig. 1). Peak values of PAHs and TBT were also detected at these locations (Martínez-Lladó et al. 2007; Díez et al. 2002, 2006).

Sampling campaigns conducted in 2003 and 2005 showed that Zn, Cu and Pb remained to be dominant, though a remarkable decline in the concentration of all heavy metals (particularly Hg and Pb) and PCB throughout the harbour was observed. Over the period 2002–2005, the percentage of average concentration in Port Vell decreases in the range between 20% and 34% for Hg, Pb and PCB, between 9% and 15% for As, Zn and Cd, and no decline was observed for Cr and Cu. The opening of the northern mouth is likely to play an important role with the increase of the harbour flushing and new currents across the harbour. A similar effect of the two opposing entrances in the Ceuta harbour (Spain) that represents an important environmental advantage in relation to conventional harbours (with a single entrance) has been reported (Guerra-García and García-Gómez 2005).

Figure 2 shows the concentrations of contaminants over the period 2002–2005 for the sampling station C-1. It must be pointed out that this sampling station is located in the innermost part of the harbour, and, consequently, it is expected to be the less-affected station by the opening of the new harbour mouth. Figure 2 shows that the highest decrease corresponds to Cd, Pb and Zn (with percentages of 53%, 41% and 36%, respectively). The decline observed for Hg, Ni and As was less pronounced (20%, 15% and 10%, respectively), whereas no decline was observed for Cu, Cr and PCB.
https://static-content.springer.com/image/art%3A10.1007%2Fs11270-009-0044-6/MediaObjects/11270_2009_44_Fig2_HTML.gif
Fig. 2

Evolution of sedimentary concentrations of heavy metals, arsenic and PCB at station C-1. Dotted line defines the exact time when the new entrance was opened

3.3 PCBs

Analysis of sedimentary PCBs revealed that they were widespread at Barcelona harbour, with a distribution pattern that generally paralleled that of metals (Table 1). In the 2002 sampling campaign, the PCB concentrations ranged from 14 μg kg−1 up to 1,829 μg kg−1 (average concentration of 405 μg kg−1). Similar to heavy metals, the most enriched sediments were encountered at stations C-13 (1,829 μg kg−1) and C-12 (915 μg kg−1). A second hot spot was located around locations C-10 and C-11 (502 and 445 μg kg−1, respectively). The remaining stations in the inner harbour show an average PCB value of 216 μg kg−1.

Campaigns carried out in 2003 and 2005 showed a slight decrease in average concentrations of PCBs in Port Vell after the opening of the northern mouth (Table 1). On an average basis, the PCB values in the inner port were 205 μg kg−1 (in 2003) and 266 μg kg−1 (in 2005). These campaigns also showed a remarkable decrease towards the southern mouth with averages of 93 and 61 μg kg−1 in the outer harbour for 2003 and 2005, respectively.

Temporal PCB trends at station C-1 are shown in Fig. 2, with levels of 233 μg kg−1 in 2005 (versus 273 μg kg−1 in 2003 and 217 μg kg−1 in 2002). Following the opening of the new entrance, this sampling station did not reveal any significant decline of its concentration since PCB degradation is very slow and it is basically by anaerobic reductive dechlorination and only when coupled with aerobic biodegradation, a complete PCB mineralization is achieved (Bedard 2008).

3.4 Comparison of Sedimentary Metals and PCB Contents with Literature Data

Heavy metal, As and PCB levels in Barcelona harbour were compared in Table 2 with data from other European and Mediterranean harbours. Of particular interest is the study carried out by Casado-Martínez et al. (2006), where four locations in Barcelona harbour were sampled for a rapid ecological assessment.
Table 2

Comparison between the Barcelona harbour and different Mediterranean and European harbours reported in the literature

Harbour location

No. stations

TOC

Hg

Cd

Pb

Cu

Zn

As

Ni

Cr

Σ PCBs

Reference

%

mg kg−1

mg kg−1

mg kg−1

mg kg−1

mg kg−1

mg kg−1

mg kg−1

mg kg−1

μg kg−1

Bilbao (Spain)

3

1.5–1.7

0.2–1.4

0.04–2.0

40.7–285.9

23.0–204.1

122.4–777.5

21.71–104.0

15.7–32.0

3.5–23.1

22.1–256.2

Casado-Martínez et al. 2006

Pasajes (Spain)

3

1.4–2.0

1.1–1.4

0.04–0.7

154.9–293.7

158.1–167.1

576–1,085

23.8–39.1

19.6–33.5

18.6–26.7

240–740

Casado-Martínez et al. 2006

A Coruña (Spain)

3

0.5–0.8

0.5–6.4

0.3–1.0

54.1–259.6

35.3–209.1

134.9–513.2

13.6–27.4

19.2–20.0

28.7–33.4

40.4–254.4

Casado-Martínez et al. 2006

Barcelona (Spain)

4

0.3–1.8

0.9–4.12

0.9–2.9

86.7–455.3

74.9–601.1

219.7–1,165

17.4–29.0

18.9–32.3

59.5–105.2

49.2–272.9

Casado-Martínez et al. 2006

Huelva (Spain)

4

0.1–2.0

0.04–2.4

1.3–4.4

5.3–384.7

1.9–1,938.0

20.9–2,458

4.7–840

0.8–129.0

9.7–32.9

2.0–2.3

Casado-Martínez et al. 2006

Cadiz (Spain)

4

0.1–2.4

0.05–2.0

0.9–1.3

5.1–86.9

7.0–202.8

21.2–378.3

3.4–30.8

0.06–21.2

0.1–14.9

nr

Casado-Martínez et al. 2006

Cartagena (Spain)

4

0.8–1.1

21.6–136.4

6.8–98.5

486.7–1,397

171.1–665.9

900.8–8,661.0

62.6–101.5

15.3–29.0

29.5–66.6

107.6–468.2

Casado-Martínez et al. 2006

Ceuta (Spain)

21

0.8–13.9a

nr

nr

10–516

5–865

29–695

4–42

8–671

13–381

nr

Guerra-García & García-Gómez 2005

Keratsini (Greece)

10

nr

nr

nr

nr

nr

nr

nr

nr

nr

47.8–351.8

Galanopoulou et al. 2005

Bagnoli (Italy)

42

1.4–6.2a

0.01–9.3

0.01–3.2

52–896

0.5–126.1

91–2,313

0.5–4.0

0.01–52.5

4–54

4.5–91.1

Romano et al. 2004

Trieste (Italy)

7

nr

nr

4.2–7.4

166–494

50.7–390

277–879

nr

nr

nr

nr

Solis-Weiss et al. 2004

Naples (Italy)

189

0.1–4.0

0.01–139

0.01–3

19–3,083

12–5,743

17–7,234

1–1,121

4–362

7–1,798

3–899

Sprovieri et al. 2007

Cortiou (France)

26

0.2–4.8

nr

nr

nr

nr

nr

nr

nr

nr

12.7–1,559.3c

Wafo et al. 2006

Alexandria (Egypt)

25

nr

nr

nr

nr

nr

nr

nr

nr

nr

0.9–1,210

Barakat et al. 2002

No. 31 Dutch harbours (The Netherlands)

279

<0.5–9.8

<0.05–9.9

<0.3–8.4

<5–250

<5–180

<10–1,000

<4–69

<3–80

<15–200

<1–456

Stronkhorst and van Hattum 2003

Rotterdam (The Netherlands)

51

11–16a

0.4–0.8

0.6–1.8

40–60

20–40

120–190

nr

9–20

nr

nr

van den Hurk et al. 1997

Cork (Ireland)

4

2.8–3.7

nr

<0.1–0.6

16.4–51.8

13.3–54.3

99.1–214.1

nr

nr

nr

0.4–1.1

Kilemade et al. 2004

Ventspils (Latvia)

35

nr

0.01–0.07

<1

3–44

2.8–28.9

16.9–254

<3

5–35

12–71

nr

Müller-Karulis et al. 2003

Bergen (Norway)

27

nr

0.3–38

nr

24.0–1,920

25.2–1,090

46.0–2,900

nr

nr

nr

nr

Paetzel et al. 2003

Barcelona (Spain)

30

<1–7.7b

0.9–19.8

0.3–3.8

52–696

55–784

106–1,165

11–47

18–47

32–109

0.6–1,829

This study

nr not reported

aReported as organic matter

bEstimated by loss of ignition

cIncluding congeners #118, #138, #153, #180

The percentage of organic matter found in our study ranged from 0.3% to 7.3% (average 2.5%). This average content is typical of Dutch, French and Italian harbour sediments (Stronkhorst and van Hattum 2003) but higher than those reported in other Spanish harbours (Casado-Martínez et al. 2006).

Levels of Pb, Cu, Zn and Hg in Barcelona harbour were generally higher than those reported for a number of Dutch (Van den Hurk et al. 1997; Stronkhorst and van Hattum 2003), Spanish (Casado-Martínez et al. 2006; Guerra-García and García-Gómez 2005), Irish (Kilemade et al. 2004) and Latvian harbours (Müller-Karulis et al. 2003). They were similar to the levels reported in Italy (Solis-Weiss et al. 2004; Romano et al. 2004; Sprovieri et al. 2007) or Norway (Paetzel et al. 2003) and lower than those reported for Cartagena harbour (Casado-Martínez et al. 2006). The Cd, Ni, Cr and As levels were comparable or slightly lower than those reported in Table 2. It is worth stating that the metal concentration ranges found in this study were wider than those reported for Barcelona harbour in a previous work (Casado-Martínez et al. 2006), probably due to the higher number of stations in the present study.

PCB concentrations observed in Barcelona harbour revealed that it is somewhat more contaminated than other harbours and coastal sediments. The PCB levels in coastal sediments were generally comparable to Marseille (France; Wafo et al. 2006), Alexandria (Egypt; Barakat et al. 2002) and Naples (Italy; Sprovieri et al. 2007); and to a lesser extent to Keratsini (Greece; Galanopoulou et al. 2005) and Pasajes and Cartagena (Spain; Casado-Martínez et al. 2006) but generally one to two orders of magnitude higher than those reported in Cork (Ireland; Kilemade et al. 2004) and Huelva (Spain; Casado-Martínez et al. 2006).

3.5 Parameter Correlations

Table 3 gives the correlation coefficient matrix for parameters determined in the sediments of the Barcelona harbour for the 2002, 2003 and 2005 campaigns.
Table 3

Linear correlation coefficient matrix for parameters determined in the surface layer of the Barcelona harbour

 

TOC

Hg

Cd

Pb

Cu

Zn

As

Ni

Cr

2002 n = 15

Hg

0.01

        

Cd

0.33

0.11

       

Pb

0.16

0.59

0.57

      

Cu

0.35

0.61

0.36

0.74

     

Zn

0.49

0.27

0.75

0.78

0.72

    

As

0.06

0.71

0.22

0.81

0.67

0.45

   

Ni

0.30

0.17

0.84

0.64

0.42

0.72

0.36

  

Cr

0.03

0.00

0.33

0.20

0.10

0.24

0.11

0.39

 

Σ PCB

0.04

0.95

0.08

0.50

0.60

0.25

0.65

0.15

0.01

2003 n = 14

Hg

0.09

        

Cd

0.84

0.08

       

Pb

0.43

0.79

0.44

      

Cu

0.53

0.64

0.58

0.95

     

Zn

0.68

0.42

0.81

0.83

0.93

    

As

0.02

0.91

0.06

0.64

0.52

0.33

   

Ni

0.76

0.06

0.74

0.28

0.41

0.60

0.09

  

Cr

0.11

0.01

0.37

0.02

0.28

0.13

0.01

0.23

 

Σ PCB

0.49

0.70

0.57

0.93

0.93

0.86

0.58

0.75

0.00

2005 n = 8

Hg

0.34

        

Cd

0.65

0.55

       

Pb

0.62

0.89

0.71

      

Cu

0.65

0.86

0.73

0.99

     

Zn

0.72

0.80

0.83

0.97

0.98

    

As

0.31

0.83

0.61

0.77

0.77

0.74

   

Ni

0.69

0.52

0.84

0.74

0.75

0.83

0.40

  

Cr

0.60

0.76

0.78

0.88

0.90

0.91

0.88

0.64

 

Σ PCB

0.56

0.61

0.76

0.61

0.66

0.69

0.57

0.59

0.66

Statistically significant correlation coefficients (P < 0.05) are printed in bold

Although a correlation of heavy metals with organic carbon in marine sediments has been well documented (Kilemade et al. 2004; Müller-Karulis et al. 2003), no apparent correlation (r2 < 0.50) was found between organic matter content and each contaminant in Barcelona harbour. Secondary processes in sediments (e.g. complexation of metals with dissolved organic and inorganic ligands, co-precipitation with Fe and Mn oxides and adsorption onto these precipitates) may contribute to the partitioning of metals into marine sediments and might, at least partially, explain the poor correlation of contaminants with organic matter (Daka et al. 2003; Cappuyns and Swennen 2004). Moreover, it should be taken into account that this is not a “natural” ecosystem but a highly impacted one, where additional spills of heavy metals and/or organic matter may take place not allowing the equilibration between both phases.

In general, for all the campaigns and among individual metals, a good correlation (r2 > 0.8) was found for pairs Pb/Cu, Pb/Zn and Cu/Zn (Table 3). This high correlation, coupled to the analogous spatial distributions observed in the harbour area, suggests that common sources and/or similar processes might govern the behaviour of these heavy metals. Zn/Cu-based anti-fouling boat paints have been reported to be commonly used since the ban of TBT-based anti-fouling paints in the late 1980s (Paetzel et al. 2003; Guerra-García and García-Gómez 2005; Sprovieri et al. 2007). These anti-fouling paints typically contain Zn and Cu in the range of 15–30% (Guerra-García and García-Gómez 2005). Moreover, Pb/Zn pair in marine sediments has also previously been reported and it is related to vehicle emissions associated to high traffic conditions (Paetzel et al. 2003; Sprovieri et al. 2007). Furthermore, the presence at high levels of Zn/Pb/Cu has also been related to the corrosion of water pipelines and to the leaching of anti-fouling paints used to protect submerged structures (Guerra-García and García-Gómez 2005; Kelderman et al. 2005). Finally, urban sewage typically contains high levels of Zn/Pb/Cu and its discharge into the harbour may have contributed to the loads of these metals. Considering that the volume of ship and vehicle traffic in and around the harbour is both considerably high and the discharge of urban sewage and other wastewater in the harbour was common practise for many years, the sources mentioned above should not be disregarded in the present study and may explain, at least partially, the relationships between Zn/Pb/Cu.

High correlations (r2 > 0.8) were also sporadically found for Pb/As, Cu/As, Cd/Ni, Cd/Zn and Hg/PCB pairs, and there were also reasonable cross-correlations between several of the substances (Table 3). However, on the basis of the current data, it is difficult to point out a single major source for these contaminants in Barcelona harbour. Potential sources of contamination were numerous and widespread across the Barcelona harbour, including historical domestic and industrial wastewater discharges, shipping activities, air pollution, corrosion of submerged structures and urban development, among others.

It is noteworthy that, despite the enhanced portuary flushing caused by the opening of the northern mouth, an increase in the number of correlated pairs was observed over time (Table 3). This might be speculated to be due to a reduction in either the local contaminant loads and/or the number of point sources.

3.6 Comparison of Sedimentary Concentrations Against SQGs for Ecotoxicological Significance

In order to assess the likely toxicity resulting from the presence of heavy metals and PCBs in the harbour sediments, the concentration of these chemicals was compared against SQGs. SQGs are being effectively employed as a screening tool to identify and prioritise chemicals of most concern and to assess the ecotoxicological significance of sedimentary contaminants in the absence of direct biological effects data (DelValls et al. 2004).

Generally, SQGs categorise the risk using two assessment benchmarks: the effects range low (ERL) and the effects range median (ERM). Concentrations below ERL are considered to exert minimal toxic effects, while concentrations greater than ERM are associated to probable toxic effects. Concentrations between ERL and ERM represent a range within which biological effects would occur occasionally. These SQGs have been widely applied to marine sediments worldwide (Birch and Taylor 1999, Hartmann et al. 2004; Casado-Martínez et al. 2006).

The SQGs used in the current study (Table 4) were those proposed by the National Oceanic and Atmospheric Administration (Long et al. 1995), MacDonald et al. (2000) and Riba et al. (2004). Values proposed by MacDonald et al. (2000) are consensus-based SQGs derived from published SQGs and include a threshold effect concentration (TEC) and a probable effect concentration (PEC). For comparative purposes, Spanish action levels (AL) were also included. AL1 is used to identify stations where additional investigations must be carried and AL2 to identify dredged materials that are not adequate for disposal (CEDEX 1994). Finally, the SQGs proposed by Riba et al. (2004), which are defined the highest concentration non-associated with adverse biological effects (V1) and the lowest concentration associated with adverse biological effects (V2), were also considered.
Table 4

Sediment quality guidelines included in this study

Substance

NOAA (Long et al. 1995)

MacDonald et al. (2000)

CEDEX (1994)

Riba et al. (2004)

ERL

ERM

TEC

PEC

AL1

AL2

V1

V2

Metals (in mg kg−1 dw)

Hg

0.15

0.71

0.18

1.06

0.6

3.0

0.54

1.47

Cd

1.2

9.6

0.99

4.98

1.0

5.0

0.51

0.96

Pb

46.7

218

35.8

128

120

600

260

270

Cu

34

270

31.6

149

100

400

209

979

Zn

150

410

121

459

500

3,000

513

1,310

As

8.2

70

9.79

33.0

80

200

27.4

213

Ni

20.9

51.6

22.7

48.6

100

400

Cr

81

370

43.4

111

200

1,000

Total PCB (μg kg−1)

22.7

180

59.8

676

The sampling campaign carried out in 2002 before the opening of the new entrance exhibited by far the highest concentrations (Table 1). Most of the stations showed Zn, Cu, Pb and PCB concentrations exceeding the ERMs considered and falling between the two values proposed by CEDEX and Riba et al. (2004). For Hg in particular, some concentrations were up to 30 times greater than the ERM. Ni and As also showed relatively high levels in relation to their benchmarks, surpassing ERL, TEC and V1 at most of the stations but generally lower than ERM, PEC, AL2 and V2. Levels of Cr are between the ERL and ERM, and Cd showed lower concentrations than ERL, PEC and AL1. The station C-7 is the only one that did not exceed any of the upper SQGs values for none of the contaminants.

According to these results, sediments of the inner port were clearly polluted by heavy metals (mainly Hg, Zn, Cu and Pb) and PCB and showed concentrations where adverse biological effects should be expected.

Subsequent sampling campaigns carried out in 2003 and 2005 showed a clear decrease in the concentrations of the contaminants (Table 1 and Fig. 2). Hg remained above ERM and PEC values at most of the stations located in the inner harbour. Furthermore, much lower values can be noticed in stations located in the inner harbour and those located in the outer harbour.

Zn, Cu and Pb exceeded their respective ERMs at stations C-1 in 2003 and C-1 and T-2 in 2005. Though below ERM, PEC, AL1 and V1, their concentrations in the remaining stations were always above ERL and TEC, although significantly lower values were observed in the outer harbour stations than those in the inner harbour. Ni and As remained above the TEC value throughout the harbour. Cr and Cd were generally lower than their respective ERL.

Distribution of exceedances of ERL and ERM is shown in Fig. 3. The major number of exceedances was found in Port Vell mostly during the 2002 survey, i.e. before the opening. Hence, in 2002, all stations in Port Vell surpassed five ERM (Hg, Zn, Cu, Pb and PCBs) in all cases except stations C-6 and C-7 (four and one exceedance, respectively). According to the AL2 values from CEDEX, most of the sediments, even in the inner harbour, would be adequate for disposal if they were dredged.
https://static-content.springer.com/image/art%3A10.1007%2Fs11270-009-0044-6/MediaObjects/11270_2009_44_Fig3_HTML.gif
Fig. 3

Number of exceedances of the effects range median (ERM) threshold found at each sampling station for the campaigns carried out before (2002) and after (2003 and 2005) the opening of the northern mouth

In accordance with these exceedances, it is noteworthy that toxicity in sediments in Port Vell could be ranked as high. These findings are consistent with the distribution of the biotic index defined by Borja et al. (2000) and derived in a previous work for a campaign carried out in 2002 (Martínez-Lladó et al. 2007).

The new entrance led to a noticeable improvement of the quality of the sediments in Port Vell. Only the stations C-1 (situated in the innermost harbour where the water flushing is lower) and T-2 (located in the neighbouring of a fuelling station) continued to show five exceedances of ERM (Hg, Zn, Cu, Pb and PCB) for 2003 and 2005 campaigns, although these exceedances were not as pronounced as in 2002. The other stations in Port Vell C-7 and T-1 exhibited only one exceedance of ERM (Hg), together with five and six exceedances of ERL, respectively. Hence, it can be concluded that the opening of the northern mouth resulted in a remarkable improvement of the quality of Port Vell sediments; however, occasional/frequent adverse biological effects are still expected.

On the other hand, stations in the outer harbour presented generally one exceedance of ERM (Hg), except for S1, S9 and S10, which showed two or three exceedances (Pb and Zn). Consequently, toxicity in sediments in the outer harbour could be categorised as intermediate. Nevertheless, it should be pointed out that previous discussion should be regarded with care. From the definition of ERM, the exceedance of ERM for a single contaminant would theoretically be enough to eliminate (or to have probable toxic effects) the fauna inhabiting a sediment. However, many species were found to survive in sediments even where ERM were surpassed (Martínez-Lladó et al. 2007). This fact leads to the conclusion that the comparison of the benthic fauna composition with the levels of contaminants (and particularly with the exceedances of ERM) cannot be simplified to a direct cause–effect relation.

It must be stressed that the bioavailability of contaminants is affected by many site-specific environmental factors such as sediment type, temperature, salinity, microbial activity and redox potential among others. SQGs must be regarded, therefore, as a screening approach providing an overall prioritisation of environmental sensitivity. Exceedances of SQG values do not guarantee actual detrimental effects (DelValls et al. 2004). Further investigations based on biological parameters (i.e. richness, density, diversity of the benthic community) would be needed to establish accurate significance of the level of pollution.

4 Conclusions

This study assesses the contamination by selected heavy metals such as Hg, Cd, Pb, Cu, Zn, Ni and Cr, As and PCBs in the Barcelona harbour sediments and reports the changes in their concentration resulting from the opening of a new mouth in the northern area.

Before the opening, the sedimentary metal contents in the inner harbour ranged from about 30 to a few thousands milligramme per kilogramme for Pb, Cu, Zn and Cr whereas from <1 to approximately 50 mg kg−1 for Hg, Cd, As and Ni. PCB concentrations ranged from 14 to 1,829 μg kg−1.

A comparison with SQGs and data from other harbours on a worldwide basis showed that Hg, Zn, Cu, Pb and PCBs appeared to be the contaminants with greatest potential to cause adverse biological effects. These contaminants exceeded the ERM's threshold in most of the sampling stations and Hg in all of them.

The opening also led to a remarkable decrease in the contaminant concentrations and an improvement of the sediment quality, due likely to a higher renewal of water which decreases the residential time of the harbour waters from 17 days (2002) to the current 5 days (2007). Sampling stations located in the innermost area of Port Vell still presented exceedances of ERM for some contaminants (particularly Hg, Zn, Cu, Pb and PCBs). Hence, it can be concluded that while the opening of the northern mouth resulted in a decrease in the concentrations of contaminants, frequent adverse effects to benthic communities are still expected in some locations of Port Vell.

Acknowledgements

This work was funded by MCYT (project PROFIT FIT-140100-2003-121) and CICYT (project REN2002-04138-C02-02). V. Martí and S. Díez would like to express their gratitude for the financial support of the MCYT through the Ramon y Cajal programme and X. Martínez-Lladó for the financial support of Generalitat de Catalunya (FI programme). The Institut Cartogràfic de Catalunya provided the cartographic layers used.

Copyright information

© Springer Science+Business Media B.V. 2009