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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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THE BOXES, THE ARROWS, TIME and SPACE
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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THE BOXES, THE ARROWS, TIME and SPACE
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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THE BOXES, THE ARROWS, TIME and SPACE
Degradation (chemical)Photolysis
Hydrolysis
Redox
Biodegradation
Cx
Fin Fout
CinCout
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THE BOXES, THE ARROWS, TIME and SPACE
Dissipation (physical)Volatilization
Partitioning
Cx
Fin Fout
CinCout
Cy
Abiotic
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THE BOXES, THE ARROWS, TIME and SPACE
Dissipation (physical)Volatilization
Partitioning
Cx
Fin Fout
CinCout
Cy
Cz
Abiotic
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THE BOXES, THE ARROWS, TIME and SPACE
Dissipation (physical)Partitioning
Cx
Fin Fout
CinCout
Cw
Cy
Cz
Biotic
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THE BOXES, THE ARROWS, TIME and SPACE
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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THE BOXES, THE ARROWS, TIME and SPACE
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)
Same family different isomers?
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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
Same family different isomers?
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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