1. Variation in the concentration of polycyclic aromatic hydrocarbons (PAHs) in mussels ( Mytilus galloprovincialis ) at the galician coast after the prestige oil spill. Ó. NIETO 1, J. ABOIGOR 1, L. SACO-ÁLVAREZ 2 and R. BEIRAS 2. 1 Department of Analytical and Food Chemistry 2 Department of Ecology and Animal Biology Faculty of Marine Sciences University of Vigo E-36310 Vigo, Spain

2. www.lavozdegalicia.es LOS HÉROES DEL 13-N. La Voz de Galicia. Jan. 2003. p 12

3. Sampling stations M1: Furnas 42º 38’ 38” N, 9º 02’ 15” W M1

4. M2: Vilar 42º 33’ 05” N, 9º 01’ 40” W M2 Sampling stations

5. M3: Aguiño 42º 30’ 59” N, 9º 01’ 00” W M3

6. Sampling dates M1M2M3 21/11/02XX- 17/12/02XX- 3/01/03XXX 22/01/03XXX 5/02/03XXX 4/04/03XXX 9/06/03XXX 12/08/03XXX 27/10/03XXX 23/12/03XXX

7. Condition index Condition index (g m -1 d.w.) M1 M2M3

8. 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

9. 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

10. Sum of PAHs date M1M2M3

11. Percentage of parent PAHs November 2002 – April 2003 June - December 2003 M1M2 M3 M1M2 M3

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

13. Sum of 6 PAHs date M1 M2 M3 [BkF] + [BaA] + [BbF] + [BaP] + [DahA] + [Ipy] < 200 ng/g (d.w.)

14. Depuration rate, r (days -1 ) C t = C 0 exp(-rt) M1M2M3 Ant0.00470.0120 / 0.00090.0023 Fla0.00700.00190.0006 Pyr0.0099 / 0.00300.00060.0088 / 0.0003 BaA0.0121 / 0.00280.0218 / 0.00350.0162 / 0.0021 Chr0.0145 / 0.00390.0194 / 0.00190.0100 BeP0.0080 / 0.00200.0108 / 0.00220.0104 / 0.0022 BbF0.0084 / 0.00270.00640.0119 / 0.0045 BkF0.0120 / 0.00210.0157 / 0.00010.0038 BaP0.0174 / 0.00180.0115 / 0.00260.0130 / 0.0011 DahA0.01390.00560.0236

15. 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: –C t = C 0 exp(-rt) –Similar values of r are found for the studied hydrocarbons. –The results suggest two mechanisms for depuration of PAHs in mussels.

16. 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