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
Acknowledgements
Financial Support:Financial Support:• MEC Spanish project PETROZOO (VEM2003-20037).
•MEC R y C contract to Carlos Barata and Albert Calbet
Objectives
Develop a modelling framework to predict the toxicity of mixture combinations of petrogenic
PAHs in copepod species
Effects of crude oil spills in marine planktonic food webs???
zooplankton species constitute the major food source for larval fish
Overview – in brief
Overview – in briefPolycyclic aromatic hydrocarbons (PAHs)
Log Kow
To
xic
ity
– E
C50
Toxicity by non-polar narcosis
1.Toxicity = F (1/log Kow)
1. Most toxic and persistent components of class 2 fuel oils (Prestige)
2. Occur in complex mixtures
Environmental fate
2.Toxicity complex mixtures is additive
Eff
ect
PAHs
Methods
Measured variables:
Lethal , Narcosis– after 48 h (%)
Test Species: Oithona davisae
Chemicals:
Naphthalene, 1-methylnaphthalene, 1,2-Dimethylnaphthalene Phenanthrene,1-methylphenanthrene,3,6-dimethylphenanthrene Fluorene, Dibenzothiophene, Pyrene
Analysis: SP -HPLC-UV
Experimental designExposure 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
Data analysis
ii
i
PAHEC
ECcontrol mobileMobile
50
50%
Modeling % responses:
Allosteric decay function
Su
rviv
al
PAHs (mol/L)
0
50
100
Data analysisModelling single and mixture toxicities (EC50) of PAHj:
bloga50
1 owj
j
KEC
Log
Kow
EC
50
Single - Quantitative Structure Activity Relationship (QSAR)
n
j j
j
ECx
c
1
1, For cj = EC 50j /n; 1 = 50%
Mixture - Concentration Addition model
Results- Single solutionsNaphthalenes (% mobile vs Control)
0 20 40 60 80
0
50
100
0 10 20 30 40
0 5 10 15
0
50
100
PAHs (mol/L)
N N1
N2
Narcosis, survival
Results- Single solutionsPhenanthrenes (% mobile vs control)
PAHs (mol/L)
Narcosis, survival
0 3 6 9
0
50
100
0 1 2 3
0
50
100
P
P1
Results- Single solutionsRest of PAHs (% mobile vs control)
0 2 4 6 8 10
0
50
100
0 2 4
0.0 0.3 0.6 0.9
0
50
100
0.0 0.2 0.4 0.6
Narcosis, survival
PAHs (mol/L)
F DBT
Ft Py
Results- QSAR
Log K ow
3.0 3.5 4.0 4.5 5.0 5.5
0.5
1.0
2.0
5.0
20.0
60.0
NarcotizationSurvival
N
N1
P1
F
DBTN2
P
PyFt
EC
50(
m
ol/
L)
R2 =0.9
5log1501 owj
j
KEC
Log
Results- MixturesMixture of 9 PAHs at their EC50/9
0 1 2 3
0
25
50
75
100
125
Toxic Units = 1 =
Survival Narcotization
(% m
ob
ile
vs c
on
tro
l
EC 50 = 1.1 (0.9-1.3)
9
j
j
9EC50
1
Conclusions
3. Mixture toxicity of PAHs was additive following the CA model.
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
Risk Assessment Implications
1 10 100 1000
0.11
10
100
1000
Naphthalene Alkylated Naphthalenes
EC
50
(g
/L)
Number Mixture components
Prestige
Highest
Background
Future Work
2 . How toxicity of real samples (elutriates or water –accommodated fractions of fuel Oil) can be predicted from Chemical analysis using QSAR models
1. Derive QSAR models for sublethal responses
2.9log0.9501 owj
j
KEC
Log
Clearance rates (feeding)
3 4 5 6
182
14
N
N2
g/L
Kow
Prestige50
Thanks
END
Environmental Toxicology and Chemistry. Volume 24, No. 11, November 2005.