Yes.

Also with us or ship

here three years

ago stores fires.

Chemistry.

Today.

Thank you very much.

Brown I hope you all hear me fine.

I really enjoyed my trip
to Georgia Tech thus far.

Met a lot of the faculty here.

I know are on from years and

he has been gracious enough to serve
on our advisory committee for a while.

Georgia Tech has a lot to

come in our department we have at
least two faculty members who are.

Alumni I actually got Ph D.
from Georgia Tech.

The longest serving faculty member
in the department in the college.

Ratified forty five years and
is still going is from Georgia Tech and

we have a more recent
faculty addition John flake.

Who also got a speech to here.

So you have a lot of contributions
to our department and I.

Really welcome all the input from Braun
as to how our apartment could grow.

My research activity as you would
see slightly different from

conventional chemical engineering but it
is what I call a giant chemical reactor.

We're looking at something
in the atmosphere which is

essentially a giant chemical reactor.

So I'm going to tell you a little bit
about some of the air quality issues that.

We have been hoping.

OK.

What I'm going to tell you what we
know about informed chemistry and

form chemistry has to do with lower
atmospheric pollution that is

what happens in the lower atmosphere
there is a great deal to know about cause

fog is not a large system it pretty much

in compasses five hundred to a thousand
meters from the surface and all of

the local pollution problems can be seen
if you look at the form and ice the form.

We have done as I would say a lot
of field study now the study

of fog is very difficult in the sense that
you cannot just go out and collect fog and

make all of the analysis based on that
you have to come back to the lab dissect

the problem into different elements and
look at individual aspects before you

can actually make some sense of what
you see in them in the real world.

So we have.

Quite a bit of walk work on the field.

Data.

I will describe a little bit of that
data give give you a flavor for

what you see in form before we go
into the laboratory studies and

why we do all of that I'll tell you why
we do all of these various different

pieces of work which tie back in with the.

Field studies and then I wrap up with what
the conclusions are from some of our work

now aerosols are a very
important problem simply because

it is one of the constituents
which is very.

Not very well known in respect of
radiative forcing in the atmosphere.

This is a prat which is very common and
very well

known it is from the I.P.C.C.
two thousand and seven assessment of what

each individual compound the atmosphere
would contribute to the global warming.

You will see that everything in the red
is actually positive effects that is they

will do contribution global warming
everything in the blue is actually global

cooling effects or
the negative radiating effect and I was.

You would notice that
the confidence bands around these

things are fairly tied when it comes
to C O two into stratospheric ozone and

black carbon and the like and even so
I really inspired when it comes to

the compounds that the material that you
see here aerosols there is a very large

uncertainty and that is because we are you
know very little about aerosols and

their effects on global warming and
therefore there is a necessary and

there is a require there is an interest
in learning more about how aerosols

contribute to global warming and
in that respect for others I never saw and

that also has got some
effects in the US Now if you

look at concentrations all
over the world and the Tsar.

A sampling of aerosols from
different parts of the world

the United States Europe and
even Asia and what you need to see here.

What you need to look for

here is the fact that there are fewer
principal comp components here.

The Ariana's are the green sulphate is the
red nitrate the blue ammonium orange and

chloride is the purple these are the main
constituents that have been analyzing.

Almost all types of fog particle
aerosol particles in the atmosphere but

the one that is most significant
in all of these is this

green is this green one which is organic.

It forms a manger so of aerosols but yet

very little very little is known
about them more importantly we do

not even know what they are made out only
less than thirty to forty percent of

the material has actually been identified
and we are looking at the uncertainty

in terms of the global warming effect of
global cooling or whatever you call it.

We if we do not know what is in these
areas also there is very little likelihood

that we can actually predict it with much
certainty and so that's the reason why

there is a great deal of interest
in learning about yourselves.

Now there are other effects in the lower
atmosphere which we are also interested in

Iran is of course respiratory problems

when you have a fairly high air pollution
in the atmosphere the lower atmosphere you

obviously have attendant respiratory
problems that you have to consider and

of course ozone is a very important issue
in most of the lower areas and that also

has got something to do with aerosols
disability reduction that is fairly well

known aerosols effect disability and we
need to know more about aerosols we want

to predict there was ability even in the
lower atmosphere there are some effects

that are important in terms of solar
radiation for example hydrophilic aerosols

do a track water that leads to
more reflection of sunlight.

On the other hand the lifespan.

Will it will.

Increase and also the reflected
power will increase over time so

there are several issues with respect
to the lower atmosphere just as in

the upper atmosphere that we need to know.

Now and we talk about aerosols most
of you are very well we all know that

aerosols are essentially tiny
particles collectively and

in terms of the atmospheric literature.

There is a classification
of aerosols based on

the water properties that is
the water countervail soft.

For example most of
the typical air was almost

anywhere from ten to
the minus to ten microns.

And the range in size from ten
to minus two all the way to

ten to the fifty if you consider the snow
also as and ever saw in the atmosphere.

More importantly there was
a constant varies from

a very small water contant a case of air
assaults to very high in the case of rain.

Most importantly it is their lifetime.

That is more that you need to consider
rain and snow has very little very small

residence times in the atmosphere
aerosols a very long distance times and

that's the reason why there is a lot
of study on every song fallen cloud

generally have very small and
in between life time a few hours.

So if you want to sample or analyze these
things you have to do it within a few

hours and that also means you cannot get
a very large sample you'll get probably

a very limited sample and you have a lot
of difficulties trying to analyze and

determine what the properties
are of these function clubs.

Now the fog is generally formed
from the aerosol itself.

It picks up rather grows by condensation
at the same time it picks up a lot

away Pers that are in the lower atmosphere
anything that is in the lower atmosphere

will get picked up in the fog so that's
a very good indicator of the arts or

local police over time the fog rat lass.

For about three or
four hours probably some light comes on

water evaporates the fog dissipates and
the particles that

are generated in the fog remains in
the atmosphere the water's gone.

Comes back to or saw in areas such
as California on the East Coast.

When you have fog appear and
reappear appear disappear and reappear.

You have these cycles going on in
time to time on the Gulf Coast.

The same thing happens during the times
and certain times of the year

you have four forms dissipates
the air behind left behind.

We know nothing about although we
know we have a lot of things in

the air that are in those locations.

So that's the underpinning for
most of our work.

Now when the arrows are the farthest
forms in the atmosphere.

Now I've just shown this just to tell
you how complicated the system and us.

There are a variety of reactions
that can happen in the atmosphere

when a fog droplet forms how does it
form you have a very small sub Micron

cloud condensation nuclei typically
sodium chloride ammonium chloride any of

these various particles dust particles
pollen bacteria all of these

are cloud condensation nuclei around which
you have a few microns of water that.

Accumulates on the surface
into this water.

There's a likelihood of
any type of gases and so

to C O two ammonia it's seal
that can be introduced.

We have very good source of energy
sunlight with generates a very high P.

of free radicals hydroxyl proximal thing
with rocks and ozone and other radicals.

These are the primary radicals which.

Drive a certain number of
reactions in this atmosphere.

Combine that with a lot of organics and
acids and hydrocarbons and all the hives

that are generated from anthropogenic
activities industry activities.

Automobiles and such and
you now have a reactor which is

very complicated within the small micro
reactor a number of different reactions of

how would you study this it's very almost
impossible to study this at one stroke.

You have to dissect the problem
into individual problems and

that's what we really do remember also
that you now are looking at a surface

area which is much larger This is
a giant spray chamber as we work

very have a very high service area
compared to the wall and therefore most of

the process reactions are there on the
surface of these particles and droplets

that also you have to characterize so
the system is very complex.

And that leads us to this question of
what happens to chemicals when they enter

into fog reactions of water evaporates
all the particles settle out and

we know we need to know what is this
what is it that is left in the air.

Where did it start from
where it end up and

that is really where our entire research.

Now it's been clear for many years
that there's been a lot of work with

respect to the inorganic components of fog
mainly sulfur dioxide because of acidic.

Acid acidity problems in the atmosphere
some amount of work on C O two and

a lot of work on nitrates and
nitrogen compounds but

there's very little work really on
carbon compounds in the in form.

Very little almost you can see nothing.

That's the reason why we wanted to look
at what happens to gas particles and

carbon materials in fog as they form and
dissipate

the Gulf Coast area from back into
Baton Rouge where as you may all

know is one of the most heavily
industrialized areas in the country.

Probably the not the northeastern coast.

Is the only one which actually.

Has a higher concentration of industrial

components as and
used in this area there are about

if you can count of about four
hundred different chemical and

petrochemical industries located
along the border along this region.

Either they have storage
transportation manufacturing

all kinds of facilities in this area.

Iraq is also been very well known that

the pollution in one area in this in
this in the Gulf Coast is not exclusive.

It is it comes from several
different areas in that Gulf Coast

air pollutants actually migrate
across the corridor and for

example the ozone problems and
in Baton Rouge just really not a problem

that results exclusively from the problems
and Baton Rouge or Louisiana it actually

comes from some some part of it's
come from Houston and that area.

So we wanted to look at all of these
various aspects with respect to sampling

for itself in order to do this
we did a series of lab studies.

First I will show you I'm just going to
summarize the work that we did over there.

We had a lot of other collaborative work
all over the country but this is what I

was focusing on as a work that we did
along with Colorado State University.

Jeff Kalat head Colorado State has been
doing quite a bit of work in sampling.

Fog so we collaborated with him to
utilize some of us equipment and

the local universities and and.

Houston we collected several strong
samples of several air samples and

this fog samples were obtained using what
we call an active strand McLeod water

collector designed by Caltech many years
ago there were two sampling sites and

the samples were subjected to a lab
a number of different analysis primarily

the major ions Ph D.'s all rugelach carbon

major in our Gannett Highlands which
are out actually also tracked by the.

Deposition programs us years and
over our of organic compounds.

To analyze from most of these compounds
just to give you a brief summary.

The area between Baton Rouge and
New Orleans and

Baton Rouge and
Houston is about three hundred miles and

the source of pollution in the two
regions are fairly distinct in Houston.

It's mostly anthropogenic and
industrial some regular traffic.

Also in Baton Rouge there's a lot of
influence from the agricultural activities

in the northern part of the parish and

of course industrial activities
in that area as well.

So these two are fairly distinct areas
in terms of where the pollution comes

from and how.

It's migrate the type of collectors that
we use just to summarize it is one is

an impaction collector which is this one
which is actually ground based collector.

This is an active strand collector which
is about a few meters about the surface.

OK so
that this collective will actually collect

air which is not influenced
by the ground properties.

This one will collect air which is
actually right approach and the ground

surface and what better than what they do
is they draw air the in this case there

are they drop their drop of the air meets
up with a rotating screen here and.

By centrifugal force to form the.

Droplets are separated
they collect in the bars.

This is an active strand collector
the air is drawn in and you have strands.

Poly poly poly three and
half monstrous strands based on

the strand diameter you can collect
as a specific cut diameter for

droplets and the droplets
impact them impact on these and

these strands they coalesce
collect into the system

you can collect you can develop construct
devices which are three stages in this

case you have three stages there is you
can collect one particle size here.

Another particle size here and
on the third particle size here.

So you can actually determine the.

Droplets size dependent
properties as I was using this.

We also have different other collectors.

This is a single stage collector
it collects the belt fog.

This is a two stage collector and
this is a three stage collector and

all these collectors can be
employed simultaneously to do

to analyze are to obtain for example.

The single strange collector
collects about fog and the typical

diameters are about three point five
micron for the car after the fifty percent

efficiency in a single stage collector
the two the three stage version

collects droplets in these three diameters
twenty two sixteen and four microns.

So you have some.

Droplet size dependent
concentrations that you can obtain.

The large and the three stage collectors
can collect very high volumes of

air nineteen made a cuple mirror and that
is necessary here in order to get a fairly

concentrated streams of water that we
can analyze for all of these compounds.

A typical feel sampling will look
something like this and Baton Rouge.

You have several of these collectors.

Placed together and

you have an air sample which actually
collects the air simultaneously in the.

In those so
you can collect the particles separately.

We also have we also run these things.

Automatically.

So based on the visibility these
things will turn around there are some

automatic timing devices there that will
turn on when the fog starts and stops

when the fog dissipates that depending
on the visibility that the probe sees.

We will also have we also have generally
air samples that I collected before during

and after fog so you have some idea
about what is in the air before.

What is in the air during the fog and
after of arguments.

Now just to give you an example
the fog generally forms.

This is almost a ten year data
on the fog formation birth and

history in Baton Rouge it forms there's
a certain similarity in when fog forms and

fall and when it doesn't form for
example in Baton Rouge

most of the fall appears between the times
of January through April actually.

The day before yesterday we
had intense fog and back and

wrote it again appears in reappears doing
the latter part of the year which is

of trouble to November too but the reason
is the same situation with respect to.

Houston the same time period.

So we look a certain times
when we can capture the fog so

we set up these field campaigns
based on this past history.

In many cases we would either sample
during the month of January or

during the month of early
part of October November.

So we can have a.

Some chance of capturing the phone and

give you a flavor for what is in this fog.

Typically the PH of the fog is fairly low
four point three and about five in that.

RUDIN That's fairly a city a city in most
in both these regions and that's a common

a common characteristics of most fob you
have a very highly enriched system and so

the ph will be fairly low the organic
carbon actually you'll find that it

is higher in Houston than Baton Rouge
in most cases that has been in system.

There's a lot higher amount of
organic carbon that you see in the.

In the areas of Houston the water
content on the other hand is fairly

similar in both areas not a whole lot
of difference between the two areas

when it comes to the principal components
that are normally analyzed and

forgo rain and
all of the other properties mainly

chloride nitrite nitrate sulfate sodium
ammonia potassium magnesium and calcium.

You'll find that in most cases it's
dominated by either chloride or

sulphate or ammonia and for example

in most of the samples you had
a fairly high ammonium content and

content in Baton Rouge
lower in Houston and

that is mostly related to the fact that
you have a lot of agricultural activities

where you sample nitrogen
samples in Houston.

You'll find that it is more dominated by.

Chloride and and sulfate and
there is a reason for that as well.

So these characteristics are not that
different from other typical faults

that you'll feel see in other regions.

Depending on where you
are sampling the location.

Two words.

Whether you're near the Gulf Coast over
there in your urine era agricultural

areas you'll find some of these
principles components wearing

according to the location.

However they are going to compounds
that I said there's a variety of

organic compounds that you can see in this
fog but the ones that you normally can

pick out are the ones that you
call organic acids that is out.

Keynes.

I know you can sit around merits
carbon heels alkane to be zero.

Season among us and some to some extent or
else investors but then you will see that.

A large portion of it here in this case is
about thirty seven percent and this forty

one percent of the material is unknown in
the sense that not characterized at all.

They are either very high molecular weight
compounds or several compounds which we

don't know what their current composition
is but in both cases the majority of

the compounds are essentially organic
acids and that comes from oxidation.

Of several compounds in the water
as well as on the particles.

If you look at the total agony of
carbon in various samples that

we have done over the years all the way
from east best feet to California.

You'll find that for

the most proud used in samples generally
have some characteristics which

are similar to some of the four examples
that I've been collecting telephone.

Baton Rouge is somewhere in the middle.

So we have spanning a fairly
wide range in total Again

a carbon when we sample
these two locations and

that's one of the reasons why I picked out
these two to show you the variations but

there's a very very wide range of course
over the in the Rye and these past week.

You really have very little
organic carbon in the fall.

If you look at the advantage chemicals.

Here is plowed which shows the organic
carbon in the fog water in the air and

the particle separately.

What you would note is that
if you look at just the AL

canes most of the alkies the low molecular
weight Al cames are generally in

the part of particulates and
most of them are the particulates the that

is the I'm sorry the most of
the product of low molecular weight.

Generally in the air the higher molecular
weight particles are generally on

the particles and that's understandable.

The molecular way lower pressure
they have a an affinity for

these particles and
you find them in the particles.

Whereas if you get a come to something
like Poly of America you will see that

a lot of the compounds are generally
found in the particles but

then a lot of the oxy ph is that is
oxygenated once found in the water

and if you sample the air before and
after the fall and during the fall.

You can figure figure out where they
are coming from most of the oxy ph is you

don't find them in the air that we
collect very fine them in the water and

that's because the highest salability
in the water whether they result from

oxidation in the water or whether there is
some from oxidation on the particles and

then the solution the water that we don't
know and that's what we need to find out

is the same that some of the early hides
and acid tones and also all its investors.

So what type of organic
carbon Do we have in the fog.

There are two types one is obviously
disarm material soluble material and

then we have allowed a fairly large
amount of carbon which is just

dissolved in the colossal form which you
cannot separate out of the water and

the molecular rates range fairly
widely from in this case.

I don't know if you can see it but
it ranges from about five hundred two all

the way to about two thousand and

they're made up of all of these
specific compounds generally apart from

the ones that are now characterized mostly
command coming from the coral fraction.

Now and have as a matter of fact that size

related fashion if you since we are able
to collect particles are droplets

with size cutouts of four or ten and
sixteen micron or twenty two micron size.

Kind of we can actually see what is in
each particle of each size fraction what

you see is that most of the compounds are
generally and ration the smaller droplets.

And.

Most of the organic
compounds in this case.

So one is that they are enriched in
the lower in the smaller droplets

diluted away in the larger droplets and
therefore Now you can relate them to the.

Surface effects of these problems.

There's also a great deal of data that we
had obtained over the years showing that

if you look at the total again
of carbon of small droplets

as against large droplets they
are biased towards smaller droplets so

not only are the individual compounds but
on top of the total organic carbon

are biased toward smaller droplets so
they have a higher concentration and then.

In some series of wells that
we generated quite a bit of.

Pesticides were analyzed in this fog and
what we observed again was that

the concentrations of questions arise from
far higher than what you would observe.

If you were just looking at
the solubility of these chemicals and

water and this is just the measured value

against the solubility of
the compound which means that.

The value here says in this case one
hundred fifty six large times larger than

the salability in war so
again why is this why is it

that we're seeing such a high
concentration in the lower droplets and

why is it that you see some of these
compounds that you don't really

don't see in air now appearing in the fog
water and those are the questions.

Again and other series of words
most recent work on Al canes or

American dollars high showing that when
you have a very low rate of pressure

the enrichment in the water is very high.

There's a very high concentration of
form wore that seems also indicating

where the surface activity comes
into play and again for a the.

Scavenging effects you see that.

Lu molecular weight come and
the pressure compounds are a normal little

compound seem to be scavenged much
faster and the high pressure comes

that tells you to summarise
what I feel will showed

first most of the arcanes are present
in the particular gas face while

a smile is a moderate those
are present in a quest face

the carbon Professor index
shows that most of it is from.

Under projects or says the average
concentrations are generally in the range

of point eight one microgram a cubic
meter total basis we observe a lot of

low molecular weight ph in the gas phase
but only a few oxy ph is where detected no

ph is were really detected in
the liquid phase that is the aerosol.

Know we'll see these are the particles
we're up to mostly because those views

these are fairly high water so
to conclude on the field.

Well oxidation products are observed
in both regions in this

case they are rather Billy.

Of large amount of dissolved organic
carbon that we do not know what they

are about and what their
composition saw Now we also observe

very high partitioning into the fog water
much more than what you would expect from

a simple gas liquid equilibrium the drop
size dependent partitioning and Planet X.

was also interesting to observe in
these feel observations that led

us into a series of lab work that we did
in order to explain some of these effects.

Ron we wanted to look at the
characterization of organic compounds in

a most specific manner Well if you have
certain specific ph is for example poly or

matter of Commons.

What would be the oxidized products and
on the surface as well as

in the box with phase and can we tie them
back to what you see in the field work.

Do we know that because these things
are very tiny and the high surface area

what is the air water in official
It's option for these compounds and

how does that relate to the uptake
rates and want Forgan ten water films.

What type of reaction products do you
see in the fog water then finally

drop lights droplets
size dependent update and

their mass transfer effects as far
as the droplet size is concerned

if there isn't a lot of natural so
fractions in the form of water.

So what what does that have to do with
the uptake into the small problem so

there are a lot of questions
that we had from the field work

which we wanted to answer so
to do that and that was the rationale for

all this lab work and
we do the field work.

Then we do the lab work what
we have to know what the.

What the reason is the reason is we
want to obtain essentially finally for

some of the atmospheric modelers some
simplified parametric stations and

in the atmospheric models for

which we need to know some amount of
data from the field and lab on the.

We have to validate the measurement
techniques and also come up with some

master mechanism in Frost's models
which we need to employ into the.

Into the models.

To begin some of those were to claim back

from the earlier lines of work
that I did many years ago and

had to do with specific lines of evidence
for interface will accumulation of organic

compounds on droplets and
in service firms.

There were three publications
that I had in about ten years

that showed that in certain systems.

You can predict a very high concentration
on the surface of these air

water interfaces that worse that
lead us to believe that al-Qaeda and

you're looking at these systems you
now have to look at all three eclipse.

Process they collaborate in the battle
care an interface equilibrium in about

interface and the bulk water and then the
balcony equilibrium between the air and

the water and
they are all three are related.

Because if you know two of them you
can find the third one because it's

the thermodynamic relationship.

We ever had with this and

we did quite a bit of molecular dynamics
simulations with some group and

Czechoslovakia and
rubbish observers that if you look at the.

System which is a slab of water and
air on both sides.

We introduced a molecule in this case it's
benzene from one surface take it through

to the through the box and out the other
surface we look at the free energy

for that molecule we see we
find that there is a very high

a large minimum in the free
energy at the interface for

benzene showing demonstrating that
there is indeed a fairly large

accumulation of chemical at the interface
now is that also true of other compounds.

There is quite a bit of data which
shows that there is this interface and

behavior for
a lot of other compounds including.

Some of the oxidizing species
like hydraulics and species.

So we now look at a situation where

you have a high concentration of
the surface of both reactors and

there is a very good likelihood that there
is high reactivity on these surfaces.

It's also true of many other polymer
Matic compounds further work that we did.

So actually looking at
the dynamics of this process.

This is for naphthalene that is for
finance three and these minima that

you see the free energy minima now we want
to see whether we can reproduce that in.

Lab.
So we applied what we call

an inverse gas chromatography to obtain
these free energy at the surface.

What we have is you have
a primitive column loaded with

solid support in this case chromosome.

And then we have the column with
a certain amount of water so

that we know exactly precisely what
is the thickness of water in that

system then the further material
into the from a terrific column.

And look for the retention time on the
other material on the on the come out of

graph and the retention is going to be
dependent on an uptake on the surface and

the solution in the bulk surface so

the total net while I'm
retained will be on this.

So if you can get the net
Rottweiler attention from the.

Residence time and the area and the alum
of water that you have introduced in this

column then a platter will give you both
care I am capably way and it is that true.

This is for
bending a plot of the area to wall him

where he says that overall
net retention wall it

will give you a straight line
the slope will give you the slope

will give you this and the intercept will
give you the overall bulk partition.

So from this.

If you can get about partitioning
here you can relate that and

you can compare it to literature value
to show that you had the measurements

are correct in fact the rally that you
find here for Benzene is almost identical

to a variety of measurements on
the balcony equilibrium uptake.

This gives you the surface and

suction function from that
you can also get obtain.

The free energy.

Now to further do this and we also did
quite a bit of work on ten films of water.

So you can wait.

The firm take notes.

Now separately in they from
a tab of a column we can and

we are we have to indirectly obtain
that the Philip take notes here you can

actually precisely obtain the feeling by
using ellipse arbitrary by creating very

thin films of water Micron stick on
long glass films which are edged and

again we pass the paper through it and
to look for these signals at the outset.

And the variation the signals
will give you by integrating

the signal we can actually obtain
how much is on the surface.

A combined.

Set of data here.

Some of the data from the reactive
work and some of the radial work from

the inverse to ask a tad if you will as
we will see this is a logarithmic scale.

So this is one over Delta
that means Delta increases.

You are going in this direction.

So most of this data shows you both ways.

Partitioning.

This gives you the interface body and
the slopes of the two.

The slope of that line essentially
is the interface partition const.

The data that we have from
the earth compared to

the actual measured waiter and
they predicted value agrees very

well in terms of the overall free
energy the overall and be and

entropy and Sampson for many of these
compounds the predicted by the predictions

are actually from the molecular
dynamics simulations that I showed you.

Now use the data to correlate to so
you can get this for a few compounds and

then you extend the data for all the other
compounds that class in this is poly or

mavericks by using a correlation of
linear free energy correlation and

in this case it is either the so called
partition constant or the subcooling

could wave a pressure of a compound for
they both have fairly good correlations so

we have a mechanism by which we can
get this partition constant from our.

Available correlations.

So first what how do we look at
the fog droplet size depends

on the partition constants for
that we use a falling droplet reactor.

We have.

A drop of generator at the top of
our grating our office generator

we generate very fine
droplets in sequence.

We generate the compound of concern using
a generator so when this is a column.

And we introduce nitrogen to generate the
way post the waivers are introduced into

the column and we look for

the concentration of compounds in
the water that is collected here.

Within vary the droplets size and do that.

Repeat that for other droplets sizes.

And if you do that you'll have
to look at the system in terms

of what happens to the system the chemical
gets accommodated the surface and then

gets into the bulk of the liquid phase and
we generally work in it's a number much

less than a much greater than one so that
most of the individual particle regime.

They ever have partitioning to
the surface that you see here.

Depends on the this is
the droplet concentration to

the weight of concentration and fall for

that column that I showed you that is
the equation that you derive this is

the mass transfer coefficient and
for add the values are known.

So you can obtain the overall
mass transfer coefficient and

then use that mass transport for
efficient to relate to the overall.

Partition concert that I saw the overall
partitioning between the two faces.

We do that with for
many several different compounds for

let me explain this for the three parts
of concern here for benzene you see these

are the these plots are the experimental
pop rocks and there are two lines here.

One line is the simulation this
this line the broken line is

a simulation which explained which.

Introduces R. assumes only bad face
partition the solid line here assumes both

bowed and gas face partition and you don't
see a much of a difference for benzine

obviously it is not very hydrophobic But
when you go to Natalie in.

You see the the experimental
points are actually following

the the curve which shows that the which
includes the surface partitioning

is even more clearer when you
go to a compound like financing.

There is a vast difference between the
the two cases where we assume only about

face partitioning and one with both gas
trace parts service based partition.

So once again much of the data
that we obtain here can really

be tied to the fact that its
option is an important process for

many of these compounds in there
is not much of a dissolution.

We can obtain
the accommodation coefficients.

It's not much significant to explain this.

We also looked at quite a bit of things as
I said earlier I told you that a surface

tension actually has an effect
because the SO factions and

they are in this in this fog water
does affect the overall uptake

into the droplets so if you increase
the total organic carbon in the.

Droplets you will see a higher
partitioning to the surface.

This is typical So fracking fully Cason.

So fracking.

The surface tension actually goes
down as you increase the amount of SO

fact and then the question is showing
that yes indeed many of these

factors actually do present
themselves on the surface.

And the same effect.

We'll see if you look at.

The the partitioning of financing
in our benzene to the surface.

They also increase leniently as you
increase the carbon concentration

of these a factor.

Situation in the liquid face so
it's size dependent partitioning So

facts and the facts are both fairly
well established in the in this third.

Well you have all these
compounds on the surface and

you have these accidents on the surface.

Now where the presence of these compounds
of the surface and oxygen they increase or

enhance the uptake into the droplets and
to do that the same experiments that we

did with the same droplet reactor but
now introducing different types of

accidents in this reactor in this
case is also on just to explain.

And as a function of the ozone
concentration the total partitioning

to the surface there is a fairly sharp
drop a sharp increase as the ozone

concentration increases and then it
becomes fairly constant after a while.

How do we explain that one in
the overall mass transfer coefficient

is a function of three resistances
here is your resistance for a gas

phase diffusion here is the accommodation
and then that is the liquid phase.

Diffusion resistance.

If you consider those effects and airplane
the overall mass transfer coefficient and

then back out of plate your
total partition constant and

this is this is the actual reaction
rate constant at the surface.

Let me go back and show you all of this
everything else is known the case is known

from your experiment.

This is the rally that you're after you
can fit the valley to obtain the correct

value of the party and the rate constant
on the surface at the surface rate and

for both of those compounds they
follow a fairly Lang Marion

approach to constancy
in their in their rate.

How do we explain that it's a simple
language Henshilwood mechanism for

the surface reaction both the oxygen and
the compound and

so on the surface they react and they
over our rate of the reaction is then.

Surface reaction times the occupancy
times the concentration of the ozone and

the concentration of the SO
fact none the surface.

If you follow the rule
that you'll find that

the overall rate constant which is
this time status will be given by

a complex relationship ship like this
which means that case will have a linear

depends on ozone at low concentrations and
a non-linear actually and

a sympathetic approach to a constant value
at High Court was on Foreign Relations.

Exactly.
As we saw earlier and the flaw in the.

I'm sorry the the plaid
that you saw earlier.

The FIP the data was exactly based
on this particular mechanism

we also saw that many of
the water droplets that recorded

the particles also enhanced uptake and
the rate constants uptake

into these droplets are vastly enhanced
when you have even when you have so

facts on the surface obviously means
this is also a surface reaction.

Now the types of products that
we saw in these droplets for

the case of naphthalene we saw certain
very specific compounds been seen by

a couple of naphthalene diode and after
and all these are typical compounds and

in our flag samples that we saw we saw
up some amount of craftily in diode

which is actually a certain oxidation
product with respect to both from

a with respect to ozone the same

type of behavior for
a finance rain we found one thousand and

three in die on certain like a boxer and
I had drops of again alcohol.

Just like in the outhouse.

The mechanistic details for those
things we can actually go back and see.

Well if you have a naphthalene How
do you get to die own an alcohol or

an acid in this case
if you have a finance.

Three How you get back to die alone and
other compounds in this.

So most of the compounds and their
mechanisms are also fairly well known and

these mechanisms are.

Mediated essentially you have to invoke
a surface reaction out of the meat

in order to obtain these reactions.

Lastly on ten forms of water.

What happens is the same experiments
that I showed you earlier.

Now we can do this.

Introducing the typical accidents that you
need you produce these very tiny films.

Then you expose them to U.V. light.

Once you reach a certain.

Equilibrium concentration and
you can analyze both the liquid face.

By taking them to see directly.

And the gas phase by using portable M S.

What we find we find for
example in a fifteen Micron water filum or

a four hundred micron one of a limb
a follow the naphthalene concentration now

this is a constant feed of an afternoon
into the system so you have

a man constant after main concentration
then you see slow increase in the up and

the concentrations of products in these
systems because they are being formed and

what we're after is the initial rates
in A and in all these cases for

the case of naphthalene we find for
different products or for

products that you showed you earlier
by the mechanistic route and for

the from fifteen Micron film
also receive very similar.

Compound formation you find out
the the rate the rates on these

things using a very simple approach.

You look at the concentration of
the starting product the starting material

going to a product and then further going
to another product because you're fearing

a constant concentration offend your phone
or your experimental evolution of any

of the products will be followed by this
equation there are two returns one and

K two what is most interesting
is focus on the value of care.

One which is the first are a constant for

the suit of a storage constant
generally Flora about a quick reaction.

You have these great conscience for
the formation of feed.

All these products for a fifty micron.

You have these valleys which are more
in line with what you see for

the bulk reaction but with a thin
film you have a fairly higher value

compared to the take from the reaction.

It's not exclusive for this compound.

You also see it for

other compounds the way we theorize it is
that there are two reactions occurring

one is the PH transferring directly to the
liquid face and a homogeneous reaction and

the PH going to the surface phase forming
a product and the dissolving in the liquid

face the overall rate is given
by this the homogeneous rate is

independent of the Delta had previous rate
is dependent on the thickness of the cell.

So if you obtain the overall rate and

plotted against one over Delta you
should find a straight line with

an acim told of the swelling and for
both naphthalene going to come around and

the three in going to now after all you
find fairly interesting increase in

the concentration of the rate
constants and the Delta decreases.

So you're going in that range and
it's also.

Same for
many of the other compounds such as.

Finance rain and
some of the other materials as well.

Now as I said earlier you find a lot of
these new Cs are a factions in the fog

water and we have collected a lot of data
from different regions and we plot the top

of the surface tension as a function of
the salt all Gannett carbon concentration.

You'll find that the variation
is not that large it goes from

pure water seventy seventy two to about
sixty so it's the variation the surface

tension is not very large but
these materials are yet surface active.

So what are the effects of the fact and
generally you have.

Variations in concentrations anywhere
from fourteen to one hundred

milligrams of carbon per
liter in all of these things.

So let's look at what happens when
you add the fact and look for

the reactions in these products.

Strangely enough if you this is for
a naphthalene reactivity this is

the first of a rate constant as a function
of the concentration of the fact that you

introduce this the sharp decrease in the
initial state initial concentrations but

then it increases as the concentrations
of fact increase this

line here as well as here for the two
products are actually based on a reaction

mechanism which takes into account
two domains for the reaction one is

the other domain where homogeneous
an attribute is reacting softer and

then there's a heterogeneous reaction
that occurs in the Facundo me and

if you take both of those
combine combinations and

you write out the rate
constant you're going to find.

A variation based on
this because the single

garden is quenched by the surface
acting fairly rapidly

in the initial stages because
the surfactants are separated out.

However in the fact the concentration
is high the single Broxton actually

is trapped within these domains and

the reactivity is increased
because of the cage effect and

that is the reason why you see a
substantially different effect at low and

high concentrations of some facts and
that that is dependent on

the fact that you have a set of sensitized
reaction and a fact and sensitized.

Oxidation both occurring simultaneously.

So to summarize the work of the sour
face you have a triple of energy

of a sort of a which is very similar to
the triplet and idea of naphthalene and

therefore these transfer occurs because
of spin allowed and diffusion control.

Processes and that also tells you.

Something about the overall reactivity.

Of in the presence of so facts.

Some of these things can be
very complicated as it was now.

To summarize all of the things that
I've shown you two things one.

If you look at.

An air assault or a fog droplets
you have several places where these

reactions several one
the reaction in the rather or

the organic film in the air or
saw it can occur on the surface

direct reaction on the surface and
can even occur within the solid particles.

There is a reason why we need to know
all of these three things separately.

If you want to predict exactly what
happens in a form and we are far from it.

Finally just a concluding remarks.

I showed you that droplet size dependence
on uptake is explained based on

surface reactivity and
surface concentrations organic matter.

This all wrong and it matter actually
increases the concentration the liquid

face the presence of some oxidants on
the surface actually increases the uptake

of the U.V. photo chemical reactions occur
faster in thin films than in take films

and that is one of the reasons so
it was bound reaction products of earlier

in the in these cases exclusive to
the surface process and finally.

The fact that they can substantially
affect the atmospheric chemistry in high

surface area dispersal it such as for
the official behavior

becomes a very evident it's very small
full of tech misses and the photochemical

reactions occur faster in the bulk of
faster in the ten films than the bulb.

And lastly the fact it's a fact
the overall reactivity as well.

I would be remiss if I don't acknowledge
all the people who have worked with me.

My graduate students.

The post to the visiting professors and
several undergraduate students and

a group from Colorado stayed and also
from the Institute of physical chemistry

with school and
my own coworkers at Ellis you friend.

Judy.
Warner who was another faculty member who

does a lot of work on polymer
magic hydrocarbons and

that helps me analyze
a lot of the aromatic and

oxy pages that I know I
have left you with that

certain questions hanging now so
I'll be glad to answer any questions here.

Since.

I was curious to

see your office.

Concentrate.

So you.

It's all

one yes probably.

So you have these some of these typical
surface active materials in the droplets

which actually enhance the solubility
of the compound in the woman and so

you have a fairly high concentration of

compounds which are taken up into
these droplets plus the fact

that if you have very small droplets You
have also have a surface concentrations

which are not been included in their
overall bulk phase relationships.

But when you correct the overall
liquid fraction you are not

you have lost the surface space you are
essentially collecting everything that is

in the liquid You may even be a film
on the surface of the liquid which

are collecting your extracting it into
some solvent and analyzing it so you can.

Everything you know.

But all.

Air.

And we don't know why it is but
we were able to see very high.

Surface activity in that sample it
may very well be that there were

there were only one a few samples in there
that we didn't have a range built into it

if we get that for a few more samples
we'll probably be able to get a range and

it may not be an outlier it may be
just that that point isn't a lie but

the rain was within that long distance.

Yes I think so.

Myself generally do.

Yes they do and enhanced the
concentrations in those wild liquid faces.

We do not know it myself form but
if they do form yes they would and

we have no way of actually
our analyzing for it yet and

I said we still don't know exactly
what all of this ultimate compositions

ourself we can for figure out a little
bit more on the actual composition

then we can probably say well these
are my sources that are probably form.

We haven't done the black carbon yet.

So we don't know exactly yeah.

Yes Very much so

because we can see an evolution
in the size distribution of on.

Of droplets in the fog from
the formation till the dissipation

there's a certain change in the design and
they grow sensual.

And so yes there is a very distinct
likelihood that trout micro physics will

be an important effect and

we don't know much about that
here because we haven't tracked.

This.

And so.

This is what we want to know essentially
what would be the air quality.

What are the types of specific products
that are left on the particles.

Once the font dissipates
if it is actually ph is

oxidized ph is that our present there.

The implications that with regard to
respiratory inhalation toxicity is quite

different from what you would be inhaling
if it had only poly or magic sounding

so I don't know yet

about the regulatory framework but
certainly it will give you some R. and R.

And besides we were focusing mostly on
ph just by the compounds of concern and

we are al canes and out there and

some of the other compounds
which we haven't looked at.

If you have a composite knowledge
about all of these things and

you can tell you say something about the
overall toxicity of inhalation toxicity

of the air in that particular region
especially in regions which have high.

High emission.

So no no no no that's that's how I that
those are some of my pictures from

Howie so.

Thank you.