1. Acute Effects Of Single And Mixed Polycyclic Aromatic Hydrocarbons Associated To Oil Spills On The Copepod Oithona Davisae .
Carlos Barata1, Albert Calbet 2, Enric Sainz 2, Laura Ortíz 3, Josep Maria Bayona 3.
1 Laboratory of Environmental Chemistry, UPC, Terrassa
2 Dept. Biologia Marina i Oceanografia, CMIMA, CSIC, Barcelona
3 Dept of Environmental Chemistry, IIQAB-CSIC, Barcelona

2. Acknowledgements Financial Support:
MEC Spanish project PETROZOO (VEM ).
MEC R y C contract to Carlos Barata and Albert Calbet

3. Objectives
Develop a modelling framework to predict the toxicity of mixture combinations of petrogenic PAHs in copepod species

4. Overview – in brief
Effects of crude oil spills in marine planktonic food webs???
zooplankton species constitute the major food source for larval fish

5. Overview – in brief Polycyclic aromatic hydrocarbons (PAHs)
1. Most toxic and persistent components of class 2 fuel oils (Prestige)
2. Occur in complex mixtures
Environmental fate
Log Kow
Toxicity – EC50
Toxicity by non-polar narcosis
1.Toxicity = F (1/log Kow)
2.Toxicity complex mixtures is additive
Effect
PAHs

6. Methods Test Species: Oithona davisae Chemicals: Analysis: SP -HPLC-UV
Naphthalene, 1-methylnaphthalene, 1,2-Dimethylnaphthalene Phenanthrene,1-methylphenanthrene,3,6-dimethylphenanthrene Fluorene, Dibenzothiophene, Pyrene
Analysis: SP -HPLC-UV
Measured variables:
Lethal , Narcosis– after 48 h (%)

7. Experimental design Exposure scenarios Individual exposures 10 PAHs
Mixture combination of only 9 PAHs using an equitox ratio
Ci = EC50j / n ; n= 9; Cj = 1/9 TUj
Experimental conditions:
No food supply, filtered sea water (38 0/00) 20 oC

8. Data analysis [ ] EC % Mobile = mobile control ´ + EC PAH
Modeling % responses:
Allosteric decay function EC i %
Mobile =
mobile
control 50 [ ] i + i EC
PAH 50 50
100
Survival
PAHs (mmol/L)

9. Data analysis å b log a 50 1 + ´ = K EC Log c
Modelling single and mixture toxicities (EC50) of PAHj: b
log a 50 1 + =
owj j K EC
Log
Kow
EC50
Single - Quantitative Structure Activity Relationship (QSAR) å = n j
ECx c 1
1, For cj = EC 50j /n; 1 = 50%
Mixture - Concentration Addition model

10. Results- Single solutions
Naphthalenes (% mobile vs Control)
Narcosis, survival N N1
100 50 10 20 30 40 20 40 60 80 N2
100 50 5 10 15
PAHs (mmol/L)

11. Results- Single solutions
Phenanthrenes (% mobile vs control)
Narcosis, survival P
100 50 3 6 9 P1
100 50 1 2 3
PAHs (mmol/L)

12. Results- Single solutions
Rest of PAHs (% mobile vs control)
Narcosis, survival F
DBT
100 50 2 4 6 8 10 2 4 Ft Py
100 50
0.0
0.3
0.6
0.9
0.0
0.2
0.4
0.6
PAHs (mmol/L)

13. Results- QSAR Survival Narcotization R2 =0.9 EC 50( mmol/L) 1 Log = 1Ft
0.5 1
Log = 1
log K - 5 Py EC 50
owj
1.0 j
DBT
2.0 N2
EC 50( mmol/L) P1 P
5.0 F N1
20.0 N
R2 =0.9
60.0
3.0
3.5
4.0
4.5
5.0
5.5
Log K ow

14. Mixture of 9 PAHs at their EC50/9
Results- Mixtures
Mixture of 9 PAHs at their EC50/9
Survival
Narcotization
125
EC 50 = 1.1 ( )
100
(% mobile vs control 75 50 25 1 2 3 9 å
EC50 j
Toxic Units = 1 = 9 j = 1

15. Conclusions
1. Allosteric decay function predicted accurately acute responses
2. Acute responses were inversely related to log Kow
QSAR 9 PAH = Daphnia magna QSAR >100 non polar narcotics
3. Mixture toxicity of PAHs was additive following the CA model.

16. Risk Assessment Implications
Naphthalene
Alkylated Naphthalenes
1000
Highest
100
Prestige
EC 50 (m g/L) 10 1
Background
0.1 1 10
100
1000
Number Mixture components

17. Future Work Derive QSAR models for sublethal responses
2.9
log
0.9 50 1 - =
owj j K EC
Log
Clearance rates (feeding) 3 4 5 6
182 14 N N2
mg/L
Kow
Prestige
2 . How toxicity of real samples (elutriates or water –accommodated fractions of fuel Oil) can be predicted from Chemical analysis using QSAR models

18. Thanks
END
Environmental Toxicology and Chemistry. Volume 24, No. 11, November 2005.