Variation in the concentration of polycyclic aromatic hydrocarbons (PAHs) in mussels (Mytilus galloprovincialis) at the galician coast after the prestige oil

spill.

Ó. NIETO1, J. ABOIGOR1, L. SACO-ÁLVAREZ2 and R. BEIRAS2.

1 Department of Analytical and Food Chemistry

2 Department of Ecology and Animal BiologyFaculty of Marine Sciences

University of VigoE-36310 Vigo, Spain

www.lavozdegalicia.es

LOS HÉROES DEL 13-N. La Voz de Galicia. Jan. 2003. p 12

Sampling stations

M1: Furnas42º 38’ 38” N, 9º 02’ 15” W

M1

M2: Vilar42º 33’ 05” N, 9º 01’ 40” W

M2

M2

Sampling stations

Sampling stations

M3: Aguiño42º 30’ 59” N, 9º 01’ 00” W

M3

M3

Sampling dates

M1 M2 M3

21/11/02 X X -

17/12/02 X X -

3/01/03 X X X

22/01/03 X X X

5/02/03 X X X

4/04/03 X X X

9/06/03 X X X

12/08/03 X X X

27/10/03 X X X

23/12/03 X X X

Condition index

0

2

4

6

8

10

12C

ondi

tion

inde

x (g

m-1 d

.w.)

M1 M2 M3

Sample preparation• The mussels collected are of 40 to 60 mm length• The soft tissue is taken out from the shell and

frozen at -80ºC• Freeze-dry, trituration• Soxhlet extraction:

– solvent n-Hexane : Acetone– 4 cycles per hour

• Solid Phase extraction:– adsorbent: Florisil 10% deactivated– elution with n-Hexane.

• Solvent evaporation and adition of 1 ml acetonitrile

Determination: HPLC with fluorescence detection

• Chromatographic system model alliance 2690 (Waters)

• Fluorimetric detector model 474 (Waters)• Software Millenium 32 (Waters)• Column Vydac 201TP54, 4.6 x 250 mm, 5µm particle

size, Grace Vydac.• Injection volume: 20 µL• Gradient elution with water:methanol• Column temperature: 23,5ºC• Detection by programming the excitation and

emission wavelengths

Sum of PAHs

date

M1 M2 M3

PAH

(103

g K

g-1 d

.w.)

12/02 04/03 08/03 12/03 0,0

1,0

2,0

3,0

4,0

12/02 04/03 08/03 12/03 0,0

2,0

4,0

6,0

8,0

12/02 04/03 08/03 12/03 0,0

0,5

1,0

1,5

2,0

2,5

3,0

Percentage of parent PAHs

Phe Ant Fla

Pyr

BaA Chr

BeP BbF BkF

BaP

Bgh

iPD

ahA

Ipy0

5

10

15

20

25

30

35

Phe Ant Fla

Pyr

BaA Chr

BeP

BbF BkF

BaP

Bgh

iPD

ahA

Ipy

Phe Ant Fla

Pyr

BaA Chr

BeP

BbF BkF

BaP

Bgh

iPD

ahA

Ipy

Phe Ant Fla

Pyr

BaA Chr

BeP

BbF BkF

BaP

Bgh

iPD

ahA

Ipy0

10

20

30

40

50

Phe Ant Fla

Pyr

BaA Chr

BeP

BbF BkF

BaP

Bgh

iPD

ahA

Ipy

Phe Ant Fla

Pyr

BaA Chr

BeP

BbF BkF

BaP

Bgh

iPD

ahA

Ipy

% P

AH

November 2002 – April 2003

June - December 2003

M1 M2 M3

M1 M2 M3

Parent PAHs ratio

LPAH /HPAH0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

PA

H (1

03 g

Kg-1

d.w

.)

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

ΣLPAH = Nap + Ace + Flu + Phe + Ant ΣHPAH = Fla + Pyr + BaA + Chr + BbF + BkF + BeP + BaP + BghiP + DahA + Ipy

12/02 04/03 08/03 12/03 0,0

0,2

0,4

0,6

0,8

12/02 04/03 08/03 12/03 0,0

0,2

0,4

0,6

0,8

1,0

12/02 04/03 08/03 12/03 0,0

0,4

0,8

1,2

1,6

2,0

2,4

Sum of 6 PAHs 6

PAH

(103

g K

g-1 d

.w.)

date

M1 M2 M3

[BkF] + [BaA] + [BbF] + [BaP] + [DahA] + [Ipy] < 200 ng/g (d.w.)

Depuration rate, r (days-1)

Ct = C0 exp(-rt)

M1 M2 M3

Ant 0.0047 0.0120 / 0.0009 0.0023

Fla 0.0070 0.0019 0.0006

Pyr 0.0099 / 0.0030 0.0006 0.0088 / 0.0003

BaA 0.0121 / 0.0028 0.0218 / 0.0035 0.0162 / 0.0021

Chr 0.0145 / 0.0039 0.0194 / 0.0019 0.0100

BeP 0.0080 / 0.0020 0.0108 / 0.0022 0.0104 / 0.0022

BbF 0.0084 / 0.0027 0.0064 0.0119 / 0.0045

BkF 0.0120 / 0.0021 0.0157 / 0.0001 0.0038

BaP 0.0174 / 0.0018 0.0115 / 0.0026 0.0130 / 0.0011

DahA 0.0139 0.0056 0.0236

Conclusions• Overstated concentrations of PAH are found in

the mussel samples during the following months after the oil spillage– From April-June 2003, these concentrations are

similar to those found in a non polluted area.– Similar percentages of parent PAHs, with a higher

proportion of HPAH with respect to LPAH are found from November 2002 to April 2003.

• The decrease in the PAH concentrations in the mussel samples can be adjusted to the following equation:

– Ct = C0 exp(-rt)– Similar values of r are found for the studied

hydrocarbons.– The results suggest two mechanisms for depuration of

PAHs in mussels.

Acknowledgements

• MCyT (project VEM 2003-20068-C05-02) for financial support

• Dr. Emilio Fernández Suárez and the rest of LEM research group for material support and collaboration in sampling campaings

Thank you very much for your attention