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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
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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 Biology Faculty of Marine Sciences University of Vigo E-36310 Vigo, Spain
www.lavozdegalicia.es LOS HÉROES DEL 13-N. La Voz de Galicia. Jan. 2003. p 12
M1 Sampling stations M1: Furnas 42º 38’ 38” N, 9º 02’ 15” W
Sampling stations M2: Vilar 42º 33’ 05” N, 9º 01’ 40” W M2 M2
M3 M3 Sampling stations M3: Aguiño 42º 30’ 59” N, 9º 01’ 00” W
Condition index Condition index (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 M1 M2 M3 date
Percentage of parent PAHs November 2002 – April 2003 M3 M1 M2 June - December 2003 M3 M1 M2
Parent PAHs ratio ΣLPAH = Nap + Ace + Flu + Phe + Ant ΣHPAH = Fla + Pyr + BaA + Chr + BbF + BkF + BeP + BaP + BghiP + DahA + Ipy
Sum of 6 PAHs M1 M3 M2 date [BkF] + [BaA] + [BbF] + [BaP] + [DahA] + [Ipy] < 200 ng/g (d.w.)
Ct = C0 exp(-rt) Depuration rate, r (days-1)
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