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THE HOMEWORK

Show me your nasty molecule

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THE HOMEWORK

What makes it environmentally

problematic?

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THE HOMEWORK

What properties do you

remember from organic andp-chem?

If any

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THE BOXES, THE ARROWS, TIME and SPACE

What is a pollutant?

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What is a pollutant?

Generally, any substance

introduced into the environmentthat adversely affects the

usefulness of a resource or the

health of humans, animals, or

ecosystems.

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What makes a substance a

pollutant?

Generally, any substance

introduced into the environmentthat adversely affects the

usefulness of a resource or the

health of humans, animals, or

ecosystems that is persistent,

and easily transportable.

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Degradation (chemical)Photolysis

Hydrolysis

Redox

Biodegradation

Cx

Fin Fout

CinCout

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Dissipation (physical)Volatilization

Partitioning

Cx

Fin Fout

CinCout

Cy

Abiotic

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Dissipation (physical)Volatilization

Partitioning

Cx

Fin Fout

CinCout

Cy

Cz

Abiotic

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Dissipation (physical)Partitioning

Cx

Fin Fout

CinCout

Cw

Cy

Cz

Biotic

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Dissipation (physical)PartitioningBioccumulation

Bioconcentration

Biomagnification

C0.1

Fin Fout

CinCout

C1

Cy

Cz

Biotic

C10

C1000

C10000

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A NEVER ENDING CIRCLE

AIR WATER SOIL PLANTS ANIMALS

NON-CONTAMINATED COMPARTMENTS

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REACTIONS AIR WATER SOILS PLANTS ANIMALS

Hydrolysis Y Y Y Y Y

Phototransformation Y Y Y Y Y

Dissociation Y Y Y Y Y

Solubility Y Y Y Y Y

Sorption Y Y Y Y Y

Biodegradation Y Y Y Y YMetabolism N N N Y Y

Accumulation N N Y N N

Bioaccumulation N N N Y Y

Volatilization Y Y Y N N

Respiration N N N Y Y

Excretion N N N N Y

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The most toxic compound

ever known to manDioxin

2,3,7,8-tetrachlorodibenzo[b,e][1,4]dioxin (TCDD)

has a reported LD50 of 0.045 mg of dioxin/kg of body mass for rats.

(LD50 is the concentration expected to kill half a given population.)

Byproduct of synthesis of chlorophenols

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Some compounds were better!

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DDT, DDD and DDE: environmental legacy

Rappolt, RT (1973). "Use of oral DDT in three human barbiturate intoxications: hepatic enzyme

induction by reciprocal detoxicants". Clin Toxicol 6 (2): 147-51

Paul Hermann Mller won the 1948 Nobel Prize in Physiology or Medicine for his 1939 discovery ofDDT as an insecticide useful in the control of malaria, yellow fever and many other insect-vector

diseases.

Cl Cl

ClClCl

Cl Cl

HClCl

Cl Cl

ClCl

DDT

DDD

DDE

DDMU, DDA, DBP

p,p-DDT

+

o,p-DDT

SOIL

SEDIMENT

ORGANISMS

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DDT, DDD and DDE: environmental legacy

Rachel Carson (1962)

Silent Spring DDT

world-wide distribution

accumulating in organisms

ClCl

Cl

Cl Cl

2,2-Bis(p-chlorophenyl)-1,1,1-trichloroethane

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k

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Love Canal (1976)

Hooker Chemical buriedwastes in canal

residential construction on

site

chlorinated hydrocarbons

seeping into homes, schools

first large-scale EPA

intervention

led to CERCLA (Superfund)

Organic Contaminants: environmental legacy

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Woburn, MA (1980s)

TCE

wide-spread in groundwater disputed source

suspected to cause cancer

(leukemia)

A Civil Action

Jonathan Harr (1995)

Cl

Cl

Cl

H

Organic Contaminants: environmental legacy

TETRACHLOROETHYLENE

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Organic Contaminants: how do we know we did it?

biology.queensu.ca/~pearl/taste/tpics/core.jpg

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Organic Contaminants: BOXES AND ARROWS

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Organic Contaminants: BOXES AND ARROWS

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OUR GOALS?

Can we evaluate everycompound for every

compartment???

The book is 1313 pages long!

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Analytical capabilities

Low concentrations

Specific compounds

Positive identification

No metabolites

Lessons from the past: almost everything at the same time

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Different structure causesdifferent toxicity

reactivity

Partitioning

If you are not planar or largerthan 10A not that bad!

Quantitative structure-activityrelationship (QSAR) is theprocess by which chemicalstructure is quantitativelycorrelated with a well defined

process, such as biologicalactivity or chemical reactivity

Cl

Cl

Cl

Cl

O

O Cl

O

O

Cl Cl

Cl

Cl

Cl

O

O

Cl

Cl

> 1 g kg-1 >0.1 g kg-1 0.00004 g kg-1

acute toxicity (LD50 for rats)

Same family different isomers?

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Different structure

causes different toxicity

reactivity

partitioning

H3C

H2C

C

H2

H2C

Cl

H2C

CH

H3C

Cl

H3C

C Cl

CH3

H3C

CH3

~ 1 yr ~ 40 d ~ 30 s

degradation (hydrolysis half-life, pH 7)


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Different structure

causes different toxicity

reactivity

partitioning Cl

Cl Cl

Cl

OH

Cl

Cl

Cl

Cl

OH

Cl

Cl

Cl

Cl

OH

pKa: 5.04 5.40 6.35

Kp: 10 L kg-1 20 L kg-1 180 L kg-1

sorption to river sediments at pH 7


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Simplify to box models

air water

suspended matter

soil and sediment organisms

etc.

Remember the details dont simplify if simplification

underestimates an important

process

Value Engineering make your li fe easier

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PUTTING YOUR NECK ON THE LINE

http://www.youtube.com/watch?v=z4lijvIjpRw

class 1_2014

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