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1. Physicochemistry of oil and related substances and how these properties influence environmental fate and organism exposure 2. Environmental toxicology of oil and related substances, including key mechanisms of toxicity and population-level

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1. Physicochemistry of oil and related substances

and how these properties influence environmental fate and organism exposure

Ted Henry

School of Life Sciences, Heriot Watt University, Edinburgh UK

T.Henry@hw.ac.uk

Slides: http://epaquatic.org/nerc-dtc-2015/

2. Environmental toxicology of oil and related

substances, including key mechanisms of toxicity and population-level responses

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What is Oil?

Some terminology

– Oil: – Petroleum: – Organic substance: – Hydrocarbon: – Crude oil:

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What is Oil?

Some terminology

– Oil: any neutral, nonpolar viscous liquid that is hydrophobic and lipophilic (may be animal, vegetable, or petrochemical in origin) – Petroleum: a mixture of naturally occurring substances including hydrocarbons and other organic compounds – Organic substance: most substances containing carbon, almost all substances that contain C-H or C-C bond – Hydrocarbon: a compound consisting entirely of hydrogen and carbon – Crude oil: the term “petroleum” includes unprocessed crude oil and products made from refined crude oil

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But remember, release of oil is also a natural process

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But remember, release of oil is also a natural process

Santa Barbara, CA

Natural Oil Seeps account for >60%

f annual releases of oil to marine

environments

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Boiling points of some crude oil constituents

Alkanes, cycloalkanes, alkenes Branched/straight chain, aromatics 8-21 carbon atoms

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Crude Oil

Complex mixtures - weathering

– Alkanes – Cycloalkanes – Naphtheno-aromatics – Aromatics (mono – poly) – Sulfur-, nitrogen-, oxygen-ated organics – Metallo-porphyrins – Asphaltenes

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Physicochemical Properties

Molecular weight (g/mol)
Aqueous solubility (mg/L)
Vapour pressure (press. of gas (mm Hg) in eq with liq)
Henry’s Law Constant (diss. gas related to partial press.
Octanol-water partition coefficient (Kow)
Boiling point (temp: sat. vap. press. = atm. press.)

Particular to individual substances and describe their physical form and behaviour and in different media

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Clathrate is a term used to describe

the structural organization of “host” molecules around a “guest” molecule.

Hydrogen bonds hold the water

molecules together to surround a hydrophobic contaminant

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Air Octanol Water

10 50 90 50 50 10 10 90 90

2,3,7,8-TCDD Phenol Benzene

Evaluative triangle Relative partitioning of substances among different compartments

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PAHs

Naphthalene (2)

128.17 31.0 36.81 3.37

Phenanthrene (3)

178.23 1.1 0.113 4.57

Pyrene (4)

202.26 0.13 0.012 5.18

Benzo(a)pyrene (5) 252.32

0.0038 2.1E-5 6.04

Coronene (7)

300.36 0.00014 2.0E-10 6.75

Poly-aromatic hydrocarbons

MW WS Log Kow VP

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Bioavailability
Bioconcentration
Bioaccumulation

– Uptake, depuration: factors and figures

Biomagnification

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1. Physicochemistry of oil and related substances

and how these properties influence environmental fate and organism exposure Ted Henry

School of Life Sciences, Heriot Watt University, Edinburgh UK

T.Henry@hw.ac.uk epaquatic.org

2. Environmental toxicology of oil and related

substances, including key mechanisms of toxicity and population-level responses

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ADME

Absorption: routes, barriers,
Distribution: carrier proteins etc. tissue types
Metabolism: tissues, hydrophobic-hydrophilic
Excretion: renal, biliary

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AhR-Mediated Toxicity

Cyp1A

ther

mRNA Other proteins Cyp1A Toxic responses Cyp1A PAH-OH PAH PAH AhR ARNT AhR Detoxification

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Hicken et al., 2011

Introduction (topic sentences of each paragraph)

– “Oil spills such as the 1989 Exxon Valdez spill and the 2010 Deep Water Horizon disaster pose major threats to fish health and population vitality.” – “Because of logistical difficulties of identifying mechanisms

f toxicity in wild species, we use the zebrafish (Danio

rerio) model to explore the long-term impacts of sub-lethal

il exposure”

– “We hypothesized that low levels of embryonic oil exposure might influence ventricular shape, and, ultimately, cardiac output in adult animals because previous studies showed that intermediate PAH concentrations caused a compensatory dilation of the cardiac chambers in larvae”

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Hicken et al., 2011

Methods

– ZF embryos exposed (48 h) to weathered crude oil – Cyp1A activity measured – Adult fish swimming performance assay – Histology of heart

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Hicken et al., 2011

Results

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AhR-Mediated Toxicity

Cyp1A

ther

mRNA Other proteins Cyp1A Toxic responses Cyp1A PAH-OH PAH PAH AhR ARNT AhR Detoxification

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Wirgin et al., 2011

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“Our results indicate that recent evolution has
ccurred in the population as a results of

selective pressures. The bioaccumulation of high levels of persistent HAHs, minimal gene flow with populations in nearby estuaries , and strong selective pressure lead us to conclude that HR tomcod have experienced rapid evolutionary change in the 50-100 years since the release of these contaminants”