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.