Understanding Our Chemical Fingerprints: Safer Water for Our Cities
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[MUSIC PLAYING] MATT O’DONNELL: Hi,
I’m Matt O’Donnell. I’m the Dean Emeritus here. I used to do this. They let me back for one. So I thank everybody
very much for being able to host this one. I want to welcome
you, and thank you for joining us for the final
presentation of this year’s 2016 engineering
lecture series– City Smarts– Engineering
Resilient Communities. This is series. As it has in the
past, this year is a partnership with
U-Dub Alumni Association and the College of Engineering. If you’re not a member,
you should be a member, OK? There’s lots of good
things to go with it. And you can find out more at
the website for U-Dub Alumni Association– UWalum– as
you might guessed– dot com. OK, so tonight– tonight’s
the last in this series. And this morning I
thought it was absolutely appropriate– I was doing my
exercises early in the morning. NPR is in the background. And what do I hear? It’s that the EPA just
enacted stricter water quality rules for Washington State. So I knew what I
was doing tonight. So of course I go “click”– what
the hell is the new EPA water regulations? And there was, you
know, 37 dash– I don’t know what these
certain statutes are– but I found a little over
100 substances related to 65 compounds are
tracked by the EPA. But they only actually
actively monitor a few toxins, such as
dioxins and things like that, in our water supplies. But you notice 80,000
chemicals out there? 80,000– several thousand
new ones every year. And the EPA– just
higher standards– is monitoring just
a few of these. Well, where are
the substances go? They go somewhere. And so many leave chemical
traces– or fingerprints– in the water that
linger for years and impact our salmon
populations, animals and plants, and in fact
our own health and safety. So tonight’s speaker
will help us understand the scope of this
issue, and– I hope– describe some ways we
can engineer solutions to maintain our water sources. So who do we have tonight? Well, you will see quite a
contrast between short and tall in just a few seconds. And this talk will be given
by Ed Kolodziej, who’s joined the Department of Civil
and Environmental Engineering in September 2014 as part
of the UW Freshwater Science Initiative. It’s very interesting initiative
between U-Dub Tacoma and U-Dub Seattle. So he holds a joint
faculty appointment with interdisciplinary
arts and sciences at U-Dub Tacoma as a member of
the College of Engineering’s and Department of Civil and
Environmental Engineering, and is also a member of
the Center for Urban waters in Tacoma– a very
interesting institute. Maybe we’ll hear a little
bit about that tonight. His research interests include
water quality and contaminant fate in natural and
engineered systems. Now, we in academics like
that he’s published well. He’s been in Science and
other major journals. But what’s really cool
is the media’s caught on. So he’s been there for Nature,
Scientific American, US News and World Report, Yahoo! News, BBC– any others, Ed? ED KOLODZIEJ: [INAUDIBLE] MATT O’DONNELL: OK. But the list is too long, and
we should get on with the talk. So please join me in
welcoming at Kolodziej. ED KOLODZIEJ: Well, thanks
for that kind introduction. And I’d like to thank you
all for coming tonight. So the theme of our engineering
lecture series this year is resilient cities. And tonight I really
want to make a case that if we’re going to
consider resilient cities, we really need to
consider how we think and manage the
chemicals that we’re producing and using
and discharging out into the environment. Now, everyone in this
room knows there’s a lot of people on earth,
mostly in urban areas. We also know that
all those people make a wide variety
of synthetic chemicals that we really use as part
of our daily lives, right? We make pharmaceuticals
to keep us healthy. We make pesticides and
fertilizers to grow our crops and feed us. We make plastics and all
sorts of crazy chemicals that are in our clothes,
in our houses and our cars. What people don’t really
think nearly as much about is what happens to
all these chemicals after we’re done with them. In a lot of cases,
they don’t actually magically disappear, right? They actually linger
in the environment. And in fact, when you
go into the environment, you can actually find this
chemical fingerprint, composed of all these
chemicals that we’re making and using
and discharging, in a lot of places
where you look. You can find our
synthetic chemicals in our forests and
the soil under them. You can find them in the water
around us, the air we breathe, the organisms that live
in those environments, even humans– for
sure– or an organism in an aquatic environment. Really, there’s nowhere
you could go on Earth where you can’t find some trace–
some trace of chemicals that humans have
produced and used and has been discharged
out into the environment. How does that relate to cities? Well, cities are
places that concentrate people and resources together. And cities are also
places that concentrate chemical pollution and
all the adverse impacts of human actions. And it turns out that in
cities, if we can figure out our problems around urban
water an urban pollution, cities are the places
with the resources to investigate these problems
and then do something about them once we figure out
what the best solution is. So I wanted to start
thinking about resilience with this analysis that was
published in Science in 2009 by a research group led
by this guy Rockstrom. And Rockstrom and his
team of researchers basically made this case
that planetary systems are resilient if
human actions are operating within their
safe boundary spaces. And they define this
figure here– a little bit hard to see, but
these darker circles– that’s a boundary area. And if a human action for
climate change, or land system change, or using Freshwater is
within this center green area, it’s basically safe. You don’t have to worry
too much about it. But you exceed this
threshold boundary– you get up into the
yellow region– that’s an indication that you’re
in a zone of uncertainty. There might be some
adverse impacts happening from that action. And if you get out
here, near the edge, you exceed this final threshold
value into the red zone. That’s an area where
human actions are expected to have a significant
adverse impact on some important
planetary system. So really we want to make sure
that humans are staying away from these red areas,
and we’re operating within our safe boundary
places, because that’s a resilient system. So you’ll notice on
this figure that there’s this interesting label
up here– novel entities. What does that mean? Well, in the
original 2009 paper, that was originally
chemical pollution. But in 2015, it was
updated to novel entities to reflect the fact
that in addition to all these synthetic
chemicals that we’re making, we’re also making things like
nanomaterials and genetically engineered organisms. And so even though this
Rockstrom research group felt that the boundary was
really important for all these novel
entities, they didn’t feel they had enough data to
quantify it– even though they thought there was the
potential for great impacts in that category due
to our production and use of all of
these novel entities with toxic characteristics. So really, this is an indication
that we have insufficient data here. We don’t really have
enough information to really accurately assess
what all these chemicals we’re producing– putting out
into the environment, into organisms, even into our
own bodies– what that really means for us. So even though we
really haven’t addressed these chemical boundaries
holistically– for groups of synthetic
chemicals as a whole– there are some planetary
boundary estimates for individual chemicals. And here I put one up
that we’re probably all familiar with– DDT–
kind of a famous chemical. DDT actually has some
good characteristics. It’s actually a really
effective insecticide, which has probably saved
many billions of dollars in crop value since
it first started being used in the 1940s. One reason it’s effective
is that it’s long lived out in the environment. DDT is considered a
recalcitrant compound. It’s difficult for environmental
processes to break it down. In fact, DDT actually exists
out in the environment for decades and even centuries. DDT still has a use
in public health. It can be used in
less-developed countries to prevent malaria,
which is a disease that’s killing something like
700,000 people a year. And for reasons like that,
we’re still producing and using around 3,500 tons
of DDT globally. But we don’t know about DDT
because it’s a good chemical. We know about DDT
because it’s bad. It’s kind of a classic
case of a bad chemical. In addition to being
toxic to insects, DDT is actually toxic to
birds and fish as well. It’s a probable human
carcinogen. That’s not good. It bio accumulates
in the food chain. So as you move higher
in the food chain, concentrations go up. In fact, even though
DDT was banned in 1972, traces of DDT and
its metabolites are detectable in every
single person in this room here tonight. So it hasn’t even been used
in the US for 40 years, but we still have it
all within our bodies. DDT is globally transported. DDT was used nowhere
near the Arctic, but polar bears have
very high concentrations of DDT in their bodies. And DDT is an
endocrine disruptor. It disrupts calcium uptake
into bones and things like eggshells. So it results in eggshell
thinning for apex predators like bald eagles
and brown pelicans. When researchers first started
noticing localized extinction of these species in
the 1960s, that’s really what led to the
ban of DDT in 1972. We couldn’t make the bald
eagle go extinct, too. That would be traumatic
for us Americans. So because we have all
this information about DDT, we can actually calculate things
like a planetary boundary. We can really evaluate the
risk or safety the use of DDT out in the environment,
and that was an analysis that was done Selbekk in 2014. And basically Selbekk
back concluded that, because of all these
toxic characteristics or harmful attributes, that DDT
would exceed its safe space. It’d be way out
in that red region and that original
resilience diagram. DDT is also a
really good example of unintended consequences. We deal with a lot of problems
as environmental engineers that are basically
results of things that we didn’t expect to happen. We didn’t maybe think through
an action or an activity very well before we
started to do it. And somewhere along the
line we figured out, hey, that’s a big problem. We need to do
something about it. That’s really causing
us a lot of difficulty, either for humans or ecosystems
and things like that. Engineers often work on solving
these unintended consequences. That’s actually a
big thing that a lot of environmental engineers do. The real problem with
them, as a society, is that unintended consequences
are costly and difficult. They take us lot of time. We use a huge amount of
societal resources on them. So we should really
pay a lot of attention to cautionary tales like
DDT, because they point us toward where unintended
consequences might pop up. So what I want to really
cover the evening– let’s think about resilient
urban communities in a chemical context. I’ll give you a few examples
about chemical production and how we screen for
chemical safety and risk. We’ll talk about a few
research developments about the occurrence
of chemicals out in the environment. We’ll think about
their potential impacts on ecosystems and humans. And finally, we’ll take a
look at a few solutions that might lead us toward those
resilient cities– that might give us those
city smarts that we’re going to need to manage this
problem of synthetic chemical production, use, and discharge. So really, in a Seattle context,
we know Duwamish is a problem. That’s a classic example of
chemical pollution impacting our environment that costs
us a lot of resources. We want to avoid
Duwamish 2, 3, and 4. We want to see if we can head
them off before they happen. So production and
screening– so like Matt mentioned here in
the introduction, we’re producing something like
80,000 or 85,000 chemicals here in the US. In the US, we make something
like 50 billion kilograms of chemicals every
single day somewhere. And what’s even more
important to notice is that globally our chemical
production is increasing. So I put up this figure,
here, from the ACS chemical and
engineering news, which basically projects population
and chemical production out to 2050. And we can see that
global populations are expected to grow a
bit– be 30% or 40% higher. But more importantly, we
see that chemical production is expected to grow
quite substantially, to maybe be three, four, or five
times higher than it is now. And that’s an indication that
there’s an affluence effect occurring on Earth. We’re not just getting
more people on Earth, but we’re getting people who are
using the Earth more intensely. They’re using, producing, and
discharging more chemicals. So if you have a new
car, there’s about $3,500 worth of chemicals in it. If you have a new home–
$15,000 worth of chemicals. So as more and more people
get new cars and new homes, our chemical production is going
to scale disproportionately– much more dramatically
than population does. This data tells us we can expect
lots more growth in production, and we’re going to see
a lot more discharge of synthetic chemicals
out to the environment. So what can engineers
do about that? Well, engineers are
really the people that build technologies that
mitigate the adverse impacts of human actions. And to kind of illustrate
this example a little bit, I turn to kind of a famous
equation in sustainability science. This is the I=PAT equation. It says the environmental
impact of a human action is not just a function of
population, which is often something we think about
easily, but also affluence– that really represents the
intensity of an action– how intensely humans are
using resources– as well as the technology
that humans are applying toward that action. Sometimes technology
makes human actions worse. But engineers are
often the people who are building technologies
to mitigate the adverse impacts of human actions. And that’s really
where engineers have a role in this problem. So engineering– we’re
going to move the needle by building good
technologies to offset these affluence impacts that
seem to be happening globally. So if you want to
do something just to like maintain the
status quo here on Earth– you don’t want things to get
worse out in the environment. You don’t want more chemicals
going out in the environment. If this population
times affluence term is four or five
times higher, that tells us that our
technologies are going to need to be
four to five times better if we just want to
maintain the status quo. So the I=PAT
equation is actually a good way of kind of
giving a design objective to our engineering teams. It tells us where we need to
get to to maintain the status quo, or maybe in some
cases to even improve our environmental health, our
water quality, our air quality. So it’s important to
know that here in the US, there’s really a big gap between
our regulatory capabilities and the demand for
understanding chemical safety. We have 85,000 chemicals, right? We’re making 1,000
new ones per year. And yet when you look at the
US regulatory capabilities– the ability of the EPA or the
Food and Drug Administration to really evaluate
their safety– these circles are to scale. We can just do a few per year. In 1976, in the US we passed the
Toxic Substances Control Act. Since that time, we’ve been able
to screen chemicals that are about five to seven per year. The EPA has done
about 250 under TSCA. And when you include other
legislation like the Clean Water Act, we’ve
managed some look at maybe 1,200 chemicals or so. There’s a big difference
between 1,200 and 85,000, right? In that 40 year period,
we’ve banned five chemicals and we’ve mentioned
to label very, very few– maybe a few dozen–
as carcinogens or toxins. And that’s largely
because the people who are producing
and making chemicals don’t like it when
their chemicals are labeled carcinogens and toxins. We kind of have a slow
process that just is not very efficient at
collecting data and then doing something about
it, like banning a chemical that’s problematic. Here in the US, we also have
no safety screen prior to use. If you’re a chemical
manufacturer, you don’t actually
have to collect a lot of data on chemical
safety before you start to manufacture it. Production and ingredient data
is considered proprietary. It’s legally protected. So if you have something like
hydraulic fracturing fluid– we’re using huge volumes of it. We’re pumping it out into
the environment so we can get natural gas and oil back. There’s no
responsibility of anyone to actually release
the ingredient list, or understand what chemicals
are in those mixtures. And that’s kind of
a real problem when it comes to environmental
health and safety, and understanding the
consequences of human actions on the environment. So here in the US, I’d say we
have a regulatory paradigm– a way of thinking about
chemicals– that says, if a chemical makes you money
then you go ahead and make it. We’ll worry about it later. That’s really in stark
contrast to places like the EU, that use more precautionary
principle type approaches to chemicals. We have to prove that
something is safe before you can go and use it. In the US, we prove
it’s harmful and then we try and ban it later. That’s a slow process, and
it’s really inefficient. As an example of this,
I’ll point to a chemical that I’ve been working
on a little bit– this agricultural pharmaceutical
called Altrenogest. It’s this molecule up
here in the corner, if you like molecules. So Altrenoegest is actually
a potent steroidal progestin that’s actually really widely
used as an estrus synchronizer in animal agriculture. Well, what that
means is that if you give Altrenogest to an
animal, or a group of animals, you can actually control
the timing of reproduction. And that’s really important. If you want a constant supply
of pork chops, or bacon, or steaks down at
the supermarket, you need to make sure that
all your animals are basically reproducing on a very
controlled schedule, so you can produce meat
throughout the year. That’s not really
the way nature works. So Altrenogest just is the
pharmaceutical that big animal ag– industrial
agriculture– uses to accomplish this outcome. If you’re an animal
receiving Altrenogest you’ll get a dose of something
like 150 to 360 milligrams per animal over a
10 or 20 day period. I’m going to contrast that here
with ethinyl estradiol, which is a component of human
birth control pills. We’ve heard a lot of stories
in the last five or 10 years about birth control
pills in water. If you’re a human female taking
a birth control pill, roughly the same pharmaceutical
application, you might take 7.5 milligrams of
ethinyl estradiol every year– much, much less than that dose. So you think about
things like agriculture. That’s actually a big
source of pharmaceuticals to the environment. We very rarely
associate agriculture with pharmaceuticals. But there’s a lot of
pharmaceuticals and antibiotics that are used in
industrial agriculture. Altrenogest, if you use
it in swine production it’s called Matrix. If you use it in
horses, it’s actually called Regu-mate– as
in “regulate mating”. That’s actually the trade
name of Altrenogest. Incidentally, I pulled these
pictures off the manufacturer websites for these products. And I was kind of
struck by the fact that they show this happy pig
in the middle of a field, right? I can assure you that
industrial swine production looks nothing like this. Those pigs never see the sun. They never see grass. And they’re never
more than a foot away from all their companions. This picture of horses–
I think maybe these are horses that are
supposed to be dating or something like that. This might be a little
bit more accurate. So if you go on to Google
and you try and find an environmental impact
assessment for a product that’s called Regu-mate, the
top search on Google will come up with a
nine page document that was last updated in 2003. And basically that document
says that Altrenogest is not extensively metabolized. And what that data
says is that, really, those animals that are
taking Altrenogest changes can be expected they excrete it
out the environment unchanged– which is actually a
really common occurrence for a lot of pharmaceuticals. One way to make an
effective pharmaceutical is just to make sure that
your body doesn’t convert it into something else. So it’s really typical
for a lot of the drugs that humans and animals take. We excrete them out in
the environment unchanged. The data in that environmental
impact assessment took a look at the
effects of Altrenogest just on soil carbon and
nitrogen cycle microorganisms. They also looked at the
effect of Altrenogest on the growth of higher plants. And basically, the
one page of data in that environmental
impact assessment concluded that Altrenogest
was safe for lettuce, radish, wheat, and soy. And it was expected to
have no significant impacts on the environment. If you go into the
scientific literature, you look at something
like Web of Science, and you look up Altrenogest and
water– kind of a logical two terms to put together– up until
this year you actually found no results. A little earlier this year,
some collaborators and I published the first
paper thinking about Altrenogest and water. So I point to this
compound because here we have a product which is actually
called Regu-mate– “regulate mating”. We only give it a 9 page
environmental impact assessment. We don’t consider its effects on
fish– what happens to it when we release it out into water, or
any other really environmental compartment. So I think Altrenogest is a
great example of why there’s a high probability for us to
expect unintended consequences sometimes. We don’t really
have a system that’s capturing a lot of data
about these chemicals before we manufacture
a whole bunch of them and release them out
into the environment. So where does
pollution come from? So lots of people
have this stereotype about pollution,
especially in water or air, that these big point
sources are the problems. When people think
about pollution, they think about
some big factory, with a big smokestack
spewing all these toxins up into the air– or
these big pipes discharging all this dirty
foamy water into our waterways. But actually, here in
the US, big point sources are actually really
well managed. We’ve been working on
this problem as engineers for like 50 years. And we’ve actually got it mostly
under control, I would say. There are a few exceptions. And maybe I’d point to
municipal waste water effluent– this big pipe of treated
waste water– sewage– that goes out into
our receiving waters after we’re done
using that water. That might be an exception
of a point source we know we still need that
think a little bit about, and maybe improve our
treatment capabilities for. If you look at data from
the Washington Department of Ecology, they basically
say only about 10% of toxic loadings to Puget Sound
are coming from these point sources. So this is really
not the right picture for us when we think about
environmental pollution. So I’m an engineer, right? Lots of engineers in the
room– hopefully there’s some chemical and environmental
engineers in the room. That’s what my background is. I wanted to show you a
mass balance tonight. So let’s take a look at a
mass balance of ibuprofen in municipal wastewater. Ibuprofen is the active
ingredient in Advil. Lots of us take over-the-counter
pharmaceuticals like Advil when you have a headache, or
a little bit or joint pain, or something like that. And on average, in
the United States people take about five
capsules of ibuprofen per year. So that’s about 1 gram
per capita per year. We also use about 100 gallons of
water– each of us– every day. That’s about 138,000
liters per year. And if you divide
those two numbers by each other– the
mass over the volume to make concentration–
you come up with a predicted concentration
in municipal waste water for ibuprofen– which,
like Altrenogest, is basically it’s by humans unchanged. You come up with an
entry concentration in the environment of around
seven micrograms per liter. So that’s the concentration
we might logically expect to find at
a big point source like a municipal
wastewater effluent that we’re discharging out into
a river, or a lake, or Puget Sound. And I could do a
similar mass balance like this for dozens,
hundreds, and even thousands of compounds–
all with like roughly the same numbers. The numbers up here change
a little bit, right? This number varies. But for many, many
compounds, you can reasonably
expect low microgram per liter concentrations
for most wastewater derived pollutants. And then a lot of them
do have some attenuation and degradation processes. So nanogram per liter
is far more likely after you account for all
these environmental attenuation processes. Here’s an example
in Puget Sound. This is sucralose. Lots of us know this
compound as Splenda, right? It’s right over here. Sucralose is an
artificial sweetener. It has no calories. Why does it have no calories? It’s because it doesn’t
break down in your body. Your body can’t extract
any energy from it, so it’s a zero calorie
artificial sweetener. Well, we shouldn’t
be surprised, then, when we put sucralose
out in the environment that nothing happens to it. Or when you try and treat it
in a wastewater treatment, plant nothing happens
to it there, either. It’s a chemical structure
that’s resistant to breakdown. So when people like Joel
Baker and Andy James– some researchers down at the
Center for Urban Waters– have looked for sucralose
throughout Puget Sound, sucralose is basically
pervasive in Puget Sound. You basically find
it everywhere. It was detected in 94%
of Puget Sound samples, with concentrations averaging
about 20 nanograms per liter. And most all this is coming
from wastewater sources. So it’s a good example of our
chemical fingerprint coming from things like
artificial sweeteners, oftentimes highest
in concentration near our major
metropolitan areas. So what’s the pollution
reality, if it’s not those big giant smokestacks
and big ugly effluent pipes? The pollution reality is
really that non-point sources matter more. In fact, the cumulative effects
of small dispersed pollutant sources are really what seems to
be driving most adverse impacts out in the environment. I put a few examples up here. Here’s a picture of
some urban storm water. It has some motor oil. Urban storm water is
full of things from cars, like lubricants,
a lot of car care products– you know, the
waxes and polishes you put on your car. It has antifreeze in
there– brake fluid, you know, your windshield
washer fluid– all these things. So there’s a huge suite of
diverse synthetic compounds in something like
urban storm water. Around our homes
and lawns and yards, we use all sorts of
nutrients and fertilizers. We use all sorts of pesticides. A good example of pesticide
use in residential areas comes from California. California’s Central Valley is
one of the most agriculturally productive regions on Earth. You don’t actually find
the highest concentrations of pesticides in the
Central Valley way out in the agricultural areas. In fact, the city of
Sacramento is actually the pesticide hot spot in
California’s Central Valley. That comes from people using
pesticides like pyrethroids around their yard
for controlling ants, and termites, and
things like that. So usually we associate
pesticides with agriculture, but actually people on their
lawns doing something like this turn out to be really
big sources of some of these problematic compounds. So really all together
all these little polluted runoffs– all these
dispersed pollutant sources add up to big problems when
you consider them collectively. And I really think
the best mentality to have when you think
about chemicals going out the environment is
that everything we use will eventually end
up in the water. It’s not true for all compounds,
but it’s a good place to start. It’s the right it’s
the correct mentality to have when you start
thinking about this problem. So another example, here–
so I like this example. This is an article that was
published by the Puget Sound institute in 2014. And it was titled Citizens are
the Leading Cause of Toxics to Puget Sound. And I really like
this paragraph in it– “New research presented at
the 2014 Salish Sea Ecosystem Conference shows that some of
the greatest dangers to Puget Sound marine life come from our
common, everyday activities. These pervasive
sources of pollution are so woven into our lives that
they’re almost invisible to us, but it’s becoming impossible
to ignore their effects.” And I think that’s really a
classic case of what I like to call thoughtless pollution. These everyday activities were
doing– these habitual things that we do without even
thinking about them– of all our individual
citizens that, together– when you consider
them collectively– they are now the leading source
of toxic chemicals to Puget Sound. So I want to show
you another example of thoughtless pollution. Let’s just focus on
hand soap for a bit. About a month ago, I was in
Washington DC at a conference. I was at the Washington
Marriott at Metro Center hotel. The conference was low
down in the hotel here. And between a break
in sessions, I went to wash my hands
in the bathroom. And the bathroom had
the automatic water and soap dispensers. And as I wash my hands,
the soap dispenser was set such that it just kept
discharging soap into the sink. And I washed my hands, and
there probably discharged six or seven or eight squirts
of soap into the sink. It’s a little hard to see
with the lighting here, but there’s a little
puddle of green soap here that runs down into the drain. And this all
happened– you know, this was an accidental
incidental discharge. It wasn’t the soap I wanted
to get from that dispenser. I went around and looked
at the other sinks, and actually for the six
sinks in that bathroom had the same exact
soap plume, which told me that lots of the
sensors were incorrectly set. So hand soap– you
know, we think of it as a single product. But it’s really a complex
mixture of synthetic chemicals. It contains things like
triclosan, triclocarbon, ureas, diethanolamine, parabens,
lots of synthetic fragrances and colors, detergents and oils. That’s a whole suite
of synthetic chemicals that are going down the drain
from this hand soap plume. So being an engineer, I did a
mass balance on the hand soap, right? That makes me happy. I estimated that we had about
1 milliliter of hand soap in that sink. It was present four of the
six sinks in that bathroom. I counted the sinks
on that floor. There are about 40
of them, and there’s 15 floors in that hotel. I figured each sink down low
is about 10 times per hour. That’s where all the people
were in the restaurants and conference facilities. There’s a lot of traffic
in and out, right? Maybe up higher in the
hotel, I figured they’re used about four times per day. And if you just run
that mass balance, you see in that one hotel
every single day something like four to seven
liters of hand soap would be discharged
unintentionally. This is not accounting
for the hand soap that we’re using intentionally. And so we have a
gallon or two, right? Maybe you get
concerned about that. Maybe not. It’s not a huge amount. But when you scale these
types of things up to cities, they suddenly become
consequential. These numbers suddenly get
a lot bigger and more real. So we’re looking at one
product– hand soap, from one industry–
the hotel industry. And if you normalize for
the number of hotel rooms in that building–
there’s about 460 in the Washington
Marriott– you can estimate that there’s
about 9.5 milliliters of unintentional discharge
per hotel room per day. Scale that to Seattle
as an example, with its 35,000
hotel rooms, and you might expect 330 of 660 liters
of unintentional discharge of something like a hand soap. Putting that in pollution
units that we’re more comfortable with,
and more familiar, and feel more intuitive
to us– that’s like two to four barrels of hand
soap going out to Puget Sound every single day from
this accidental pathway. And I think we all
know that if this was a factory or an
industry or some big box with big smokestacks
over on the side, and we were told that hey
that industry is discharging two to four barrels of pollution
out into Puget Sound every day, we’d want to do
something about it. There would be
societally unacceptable. But the reality is,
because that impact is spread across all
the people and it comes from a habitual
thoughtless action, we end up really not
thinking much about it, even if it’s a really
important source of chemicals to our receiving waters. You do that same
type of analysis across all the other products
and all the other chemicals in all the industries we
have, and suddenly you have really significant
numbers for toxic loadings. So everything else– that’s
lots more barrels of pollution that are going to hit Puget
Sound from these sources. In fact, the Washington
Department of Ecology says something like 6
to 43 million kilograms of toxic pollutants are loaded
into Puget Sound every year, most of which is coming from
non-point source pathways. So what do we detect in water? Well, the first thing I’ll
say about detecting chemicals in water is that
the companies that make analytical instruments
do a wonderful job. Every single year they
give us instruments that are more powerful, more
capable, more sensitive– they can see all sorts of
chemicals in water and fish tissue and soil, down to
really, really low levels. So there actually happens to be
lots of chemical detections– I think especially in stories
that end up in the media– that derive simply from the fact that
we have instruments that are so powerful that we can now
see our synthetic chemical fingerprint everywhere. Right And as an example of
where we find chemicals, I put up this study here
that was led by James Meader. He’s actually a scientist
at NOAA, at the Montlake lab just down the street. He collaborates with
a U-DUb researcher named Evan Gallagher. And earlier this
year, they put out this paper called Contaminants
of Emerging Concern in Large Temperate
Estuary– that basically being Puget Sound. And that article got
a lot of attention in places like
the Seattle Times, because there are
headlines like drugs found in Puget Sound salmon
from tainted waste water. What the Meader
research group did is they went and analyzed
municipal wastewater from a couple of
places in Puget Sound. They looked at the Puget Sound
itself as the receiving water. And then they analyzed tissues
from salmon and sculpin for a wide variety of
synthetic chemicals. These are things
like surfactants, and anti bacterial
compounds, and illegal drugs like amphetamine,
things like caffeine, a whole bunch of
pharmaceuticals. And maybe not surprisingly,
these compounds are found to be pervasive in
all the samples they looked at, often at those low nanogram
per liter detections that we felt were reasonable
and kind of expected for trace contaminants
out in the environment. If you had tried to do this
study 10 or 20 years ago, lots of these detections
wouldn’t be there. The analytical power
just wasn’t there to really see these compounds. So always realize a little bit
that some of the detections we hear about and read about
come from really low levels and powerful instruments. That being said, it
is really interesting to think about the fact that
our salmon and our sculpins are actually kind of
full of the chemicals that we’re producing and
using and discharging out into the environment. That’s a problem that we’re
struggling to understand. Is it bad for those
organisms or not? I’ll talk about that
in a couple of minutes. We also have broader
detection capabilities. Our analytical
instruments give us the capability to detect
chemicals really broadly. We don’t actually need a
targeted method anymore. We just buy a
standard and really optimize a specific
instrument just to see that compound
out in the water. We have analytical instruments
like high resolution mass spectrometry instruments. This is the QTOF that’s down
at the Center for Urban Waters, that my research group
uses all the time. And they give us capabilities
for broad spectrum screening. Here I put up some data where
we looked at municipal waste water. And if we take a two liter
sample of municipal wastewater and concentrate it down onto
an extraction cartridge, we can actually detect
11,600 compounds in that single sample. Now, lots of these are actually
natural products and things that would be there even
if humans weren’t around. But this number of
detection tells us that there are
thousands and thousands of synthetic chemicals that
came from people in basically sources like
municipal wastewater. So what we’re trying to do
in my research group is look at all these detections– figure
out what chemicals are there, which ones are at high
concentrations, which ones might be toxic, which one
should we worry about the most– so maybe we can build
better treatment processes to remove them before they
add to the environment. These detections are
really our library that we look through to try and
understand chemical occurrence out the environment. So is this pollution important? Well I think it’s
really clear that we have some excellent cases where
it’s evident that poor water quality has some really
problematic effects, especially when you consider are
aquatic organisms. And a good example
of acute toxicity is what’s called pre-spawn
mortality and coho salmon. So researchers at NOAA,
and here at U-Dub, and Washington State
University Puyallup, and the Washington Department
of Fish and Wildlife have been working
on this problem for the last 10 or 20 years. Because what happens is
that here in the fall, right around the
October-November time frame– really right now– when
adult coho salmon come up into urban creeks to try
and spawn and reproduce, if it happens to rain when
they’re in those urban creeks, many of them end up dying
within about one to four hours. And that’s because there’s some
toxic chemical or chemicals in that urban storm water
that the coho are just very sensitive to. And it basically kills them. In some places in the Puget
Sound region here, up to 90% of the coho salmon that
return to these urban creeks end up dying from the
pre-spawn mortality phenomenon. So it’s really clear
that at least some of the synthetic chemicals
we’re putting out into the environment might
have some really problematic impacts. You have to recognize that if
you’re killing an adult fish– a big adult fish–
in one to four hours, that’s a pretty
powerful– that’s a pretty potent toxicant
that’s floating around out there, that
we’re probably going to need to do something about. So one thing my research
team is actually doing is we’re trying to link this
pre-spawn mortality phenomena to specific chemicals. People have been
trying to understand the cause of this toxicity
for a while– haven’t really nailed it down yet. So the toxicant or toxicants
that cause this phenomena are currently unknown. But they’re probably
car related– like highway runoff,
wet roadway runoff, might be part of the story. So what we’re
trying to do is use some of those strong
analytical capabilities in that broad
spectrum screening. We’re trying to understand
which chemicals are actually in this urban stormwater. And then we’re looking
at chemical uptake into the fish that are dying
from pre-spawn mortality phenomena. So we’re doing things
like pairing storm water samples with gill
samples– and samples from kidney and liver
and heart brain– from coho salmon that basically
died after that exposure, to understand that
the flow of chemicals from the environment
into organisms– especially to try and figure
out which ones of those are toxic and problematic. So we do that type of screening. We look for all these
suspect toxicants– or things we expect to be in storm
water– in these salmon. We start with a list of,
in this case 79, right? There’s 79 things we expect
to find in storm water that we think might
be toxic to fish. And we looked for them. And we actually can find 24 of
those toxicant candidates that are detected, not only
in that highway runoff, but are now entering the
fish after the fish are exposed to these chemicals. At least nine of our
toxicant candidates are detected in all
the tissue samples from those fish that died from
pre-spawn mortality, as well as the stormwater. And so for us, this
is a little bit of a part of the puzzle
for understanding what’s causing this
acute toxicity effect. We’re Really building the
analytical tools to watch toxicity in action. And I’m hopeful
that if we continue these efforts to
understand what chemicals are in all these different
environmental compartments– if we couple that
knowledge with insight into the biological
mechanisms of toxicity, we might be able to narrow down
our list to a specific toxicant that we can understand its
occurrence in stormwater, and we can do something
to treat it and remove it, to make the systems
better for salmon. So acute toxicity, you know,
it’s a compelling example. But it’s actually
on the rare side. Here in the US, we actually
fixed a lot of acute toxicity problems for aquatic organisms. What’s much more typical is
actually sublethal impacts. This is what’s really
quite commonly observed when you think about
synthetic chemicals getting out in the water and
affecting aquatic organisms. So as an example here, I use
the fish on Prozac example. This came out of Brian
Brooks’ research group in 2003, where he looked at
the environmental occurrence of a chemical called fluoxetine. That’s this chemical here. It’s really commonly used
as an antidepressant, right? It’s the active
ingredient in Prozac. So here in the US we have
about 25 million prescriptions for Prozac. Everybody on Prozac is taking
about 20 milligrams per day, and our per capita discharge is
about 7.3 grams of fluoxetine per person per year. So not all that different
from that ibuprofen mass balance that we did earlier. Fluoxetine ends up being
ubiquitous in wastewater because of that pervasive use. And like many other
synthetic chemicals, there’s actually
little or no removal during wastewater treatment. In many cases, wastewater
treatment plants were not designed to
remove synthetic chemicals, so they kind of remove
them only accidentally. We haven’t really
intentionally tried to remove lots of
these chemicals from sources like
municipal wastewater. So really we probably
shouldn’t be surprised that fluoxetine is
subsequently detected in fish that are
living downstream of those municipal
wastewater plant effluents. In fact, when
researchers look, they can actually detect fluoxetine
in the brains of fish that live downstream from
these municipal wastewater treatment plants. And the concentrations
in those fish brains are actually really close
to the concentrations that are pharmacologically
active in human brains. So that’s telling us that
fluoxetine is not only going from our wastewater,
it’s going into the fish and into their
brains, and probably having some effects like
antidepressant effects in the aquatic organisms
exposed to this compound. When researchers reproduce
this phenomena in the lab, they find that these types
of fluoxetine exposures reduce the fecundity of fish. So that reduces the
capability of fish to reproduce– the total
quantity of reproductive output that they have. It alters their gene expression. It makes male fish
more aggressive. Their ability to capture
prey seems to decrease. And their mating
success goes down. So this is really typical
for sublethal effects. And I could show a similar
slide with all sorts of different compounds
and all sorts of different aquatic
organisms here. These are cases where
nothing dies, right? There’s no fish up dead
on top of the water. There’s no cancer here. But important things
like reproduction, and gene expression, and
the way these animals behave and interact with
their environment are being changed
because of our exposures to the synthetic
chemicals that we’re putting out in the environment. The real challenge
for us as researchers is quantifying these. How do we make people care
that your behavior, or mating success, or fecundity
changes a little bit if you are an aquatic organism? And really the more
important question is– do these types
of sublethal impacts lead to smaller populations? From an ecological
perspective that’s really the critical question
for us to try and figure out. Because it’s important to
answer that question so we know which
chemicals we should be managing aggressively. Potential impacts on
humans– everybody is always interested in, well,
what’s it going to do to me? What’s the problem for me? And so I think it’s
quite clear that there’s plenty of low level
exposures to humans of things like pharmaceuticals
coming through indirect water pathways. And the example I
used here is one that was published by a Dutch
research group led by Houtman. And the paper was called
the Human Health Risk Assessment of a Mixture
of Pharmaceuticals in Dutch Drinking Water. And the key phrase
in that study was “unplanned, indirect
potable reuse. So let’s take a look
at what that is. Here I have a USGS
sewer service map. And basically, the
Pacific Northwest here– the Columbia River basin. And it’s a little
hard to see here, but you look up in
these watersheds and you see these
little green areas. These are areas
with sewer service. And it’s really typical,
here in the United States and throughout the
world, that you have an upstream community that
pulls water out of the river, uses it, drinks it. After we’re done with it,
it goes to the sewer system. We treat it. We put it back in the river. It gets diluted with
some other water. It flows downstream. The next community pulls it
up, uses it as drinking water, treats it, puts it back. The same thing happens
again and again as that water flows down stream. So we actually–
that’s what unplanned, indirect potable reuse is. It just means that there is
a community upstream of you. So my message here for
everyone is that everybody is downstream of somebody else. Somewhere, there’s a wastewater
effluent or a septic system upstream of you. And we should probably kind of
get comfortable with that fact. That’s the reality of
a crowded world, right? And the other thing there is
also that all water is reused. Water is actually four
billion years old. It’s been here since
the earth was formed. I have a colleague who likes
to say all water is reused– it was all dinosaur pee at least
once, and probably thousands of times. So maybe you should think
about that next time you have a nice, tall
cold glass of water. Back to pharmaceuticals in
water– one way of evaluating the risk of these
trace exposures is to compare the
concentrations we see in drinking water–
that’s all these bars right here– for a whole
range of pharmaceuticals that Houtman detected in
that Dutch drinking water, with the pharmacological
dose, which is basically the very top of the figure. So if you get up near this
risk level line, that basically says, well, the concentrations
in drinking water are close to the doses
you would receive if you took that pharmaceutical
as part of a prescription. And what you can see– note that
this is orders of magnitude. This is the log axis. It’s really typical
that the concentrations of pharmaceuticals
in our drinking water are many orders of magnitude
below the pharmacological dose levels. So from a big picture
perspective, that tells us we probably don’t
have a lot to worry about with these
exposures as humans. The health risks for
humans are likely minimal. But it’s very tough
to prove safety. And a lot of people are
kind of challenged by that. How do you prove
something is really safe? It’s not an easy thing to do. And I would say when you look
at the scientific literature as a whole, there’s no
clear sublethal impacts evident for humans
through water pathways. That story might
change a little bit when you look at chemical
exposures around your home or through your food. So here’s an example
from late October, titled The Human Cost
of Chemical Exposure. And it has this interesting
paragraph in here. “Long term, low level exposure
to endocrine disrupting chemicals costs
us $340 billion– that’s with a b–
in annual health care spending and
lost wages, according to our recent
epidemiological study.” So that’s an attention
grabbing headline. When you look at the data
that was published there, you see that most of
those economic costs came from things like PBDE
flame retardant exposure. PBDEs are these compounds here. They have all these
bromines on them. If you burn a PBDE,
it basically creates a blanket of bromine gas over
the fire and excludes oxygen. So PBDEs are
actually used really widely as flame retardants. The carpet in this
room has them. The foam in the seats
you’re sitting on have them. Probably your sofa
at home all has them. PBDEs end up coming
out of the foam. They’re not chemically
bound to the foam. You inhale them basically
as household dust. And they enter your body. And we actually have
exponentially increasing concentrations of PBDEs
in humans, especially here in the United States. Where PBDEs are implicated
in neural disruption. So there’s a case to be made
that PBDE exposure results in intellectual disability. So this study that
was recently published said that annual US prevalence
might be 43,000 cases that result in 11 million
IQ points being lost, which costs us $266 billion. You see a similar story here
for organophosphate pesticides. These are things that you
might find in your food. Again, they’re implicated
in neural development– or are altered neural
function– which results in IQ points being lost,
and a big economic cost being associated with that. So for studies
like this– there’s a lot of splashy numbers
there– but a lot of scientists would question some
aspects of this data. It’s really hard to
put a value on things like intellectual disability. What does that really mean? How accurate can
that estimate be? But I think I take home
the big picture here. Even if all these
numbers are wrong, PBDEs are things you’re going to
find in your home, where you’re spending a lot of your
time– where there’s a really complex mixture of
synthetic chemicals around you. Organophosphates–
agrochemicals are found in food. So this is a good
case to be made that our most significant
chemical burden comes from our exposures at home, and
probably not through pathways like water. So steps toward
resilient cities– because I know my own
research the best, I kind of focused a little
bit on research things I’m working on. Recognize there’s a
lot of steps we’re taking as an
environmental engineering and environmental
science community toward resilient cities. So one thing I
think we really need is better detection capabilities
and treatment capabilities for high risk chemicals. Here’s an example. Here, again, we’re
looking at pollutants in many municipal wastewater
with high resolution mass spectrometry. If we look at the influent to a
municipal wastewater treatment plant we can detect
3,200 different chemicals in this particular sample. If you look at the effluent–
the water coming out of the municipal
wastewater treatment plant that goes out
into the environment– we detect about 1,100 chemicals. 772 of them are the same
as what we detected before. That tells us our
engineered process removes about 2,400 chemicals–
maybe 70% or 80% of them are getting removed
pretty efficiently. Concentrations also decrease. You see this difference–
kind of the right side figure, the red is a little lower. The yellow is a little lower. The blue’s a little lower. That tells us that the
treatment plant is also removing some of the massive compounds. But it’s also making
some new compounds. There’s 370 new compounds,
that are probably transformation
products, that are now entering the environment. So really our challenge
as researchers is to look at all
these chemicals and figure out which
ones are most toxic. And once we figure
out which ones are most toxic and problematic
for aquatic ecosystems or humans, we can optimize
our treatment technologies to do a really good
job of removing them. That’s something that
there’s a lot of discussion, and kind of– we’re trying to
figure out, as a community, should we be really
putting a lot of investment into municipal
wastewater treatment to treat these residual levels
of contaminants that is still there, even when our
case for their safety is really not fully defined? Even better, something that
would be far cheaper and more effective, would
be doing something like source control– removing
them from production entirely. This is especially critical
for non-point source pollution. Almost all non-point
source pollution– things like urban storm water–
ends up being untreated. We simply can’t implement treat
systems across big land areas. So we’re really
going to need to look at source control as
our management tool for synthetic chemicals
in those environments, once we understand which
chemicals are most toxic. We’re also dealing
with the challenge of 85,000 different chemicals. And I can tell you, if
screening chemical safety for 85,000 things comes down
to little academic research teams– you know, a
handful of students and a professor
sitting in a room, or a group of 20 career
scientists at EPA– we’re never going
to really attack this problem effectively. So one thing myself and some
of my colleagues are doing is we’re basically trying to
build computational tools that allow us to accomplish
in silico screening. And as an example here, we’re
trying to look at receptor and enzyme binding as
a toxicity indicator. So there’s a lot of money to
be made making pharmaceuticals. And pharmaceutical
companies for many decades have created algorithms and
computational screening tools, where they can take a specific
molecule– there’s actually a chemical sitting right in the
middle of this big mix here– and try and understand if
it binds to a specific drug target, like a
protein or an enzyme, or some nuclear
steroid receptor. If you have a chemical that
fits in that binding pocket correctly, you
might have a drug. So pharmaceutical
companies build these tools to find drugs. And in this case, one
of my collaborators, Rubin Abagyan, who is down at
the University of California San Diego has this
pocketone screen which can screen different
chemicals across 2,700 different protein drug targets. So we’re trying to
take these tools that were built for drug
discovery, but now use them to identify
environmental toxicants. We can take chemicals that we
find out in the environment and put them in this
receptor binding pocket, and see if they
start to fit as maybe a first step in understanding
if they’re toxic or not. I showed a few examples
here of pharmaceuticals that you might expect to find
in municipal waste water. These are actually chlorinated
transformation products. We actually chlorinate
a lot of wastewater before we release it out
into the environment. And that actually
creates new products. So we’ve taken some
of those new products, and screened them against this. And we actually find that
some of these new products do bind to things like the
androgen receptor– this is androgen receptor here–
or the progesterone receptor, or the mineral
corticoid receptor. And that tells us
the specific pathway that we might start
to consider when assessing their potential
toxicity of compounds like this. So we really need
tools like in silico binding and computational
tools to get a handle on the tens of
thousands of chemicals we’re making and using. Because our real challenge is
to differentiate the high risk chemicals– that
small subset of that might be toxic– from
all the safe ones that the toxic ones
kind of coexist with. I also think there’s a
real opportunity for us to bring strong engineering
tools to non-point source pollution. This is especially important
in the Pacific Northwest. We all know how
much rain we get. We all know how much urban
storm water we’re generating. So I pulled the headline
here that came out early in October– “to
solve water pollution, Seattle turns to
an old solution.” And really, what we see here is
the typical urban rain garden. This is an example of
low impact development– things like urban rain gardens,
bioswales, riparian buffers. These are all kind of
like pretty simple tools that we’re trying
to use as means of improving the water
quality of things like urban stormwater. And there’s a good
quote from that article. It says “the main tools
are plants and dirt. It’s like the newest
oldest technology.” And as an engineer,
I really appreciate how wonderful and simple
plants and dirt are. But I can’t help but look at
a system like an urban rain garden and think, we
can do a better job than just mixing plants
and dirt together. There’s a lot of
opportunities to look at the systems as engineered,
multiple-barrier systems, and optimize their
performance– especially when we know which compounds in
things like urban storm water are most toxic, and
most in need of removal by our treatment systems. As an example of why
this is important, the Puget Sound
partnership estimates that we’re going to be
spending $16 billion here in urban storm
water treatment. And that’s still going to leave
most of our urban stormwater untreated. So there’s a real need for
effective mechanisms here. We’re going to be investing
a lot of resources in those, and we need to make sure
that those investments are smart and efficient. So a few closing thoughts–
why are we surprised? It’s really the case that
chemical production leads to environmental pollution. So I put an example here, again
looking at pharmaceuticals. In 2009, there were $300 billion
worth of pharmaceutical sales– Just a huge market. With a $300 billion
market– $300 billion chemical production
system– why are we surprised when we look
at drinking water? We can see traces of
pharmaceutical chemicals and hormones that have been
detected in the drinking water of 14% of the nation–
or 41 million Americans and 24 major metropolitan areas. With this big huge
production system, we shouldn’t be
surprised that 80% of 139 streams that
were sampled contained at least one pharmaceutical. So large market values–
large productions– are going to imply the
environmental occurrence of synthetic chemicals– either
the chemicals themselves, or something that’s related
to their production, or something that’s a
transformation product of them. I think our big challenge
is our research community is trying to understand what
the real environmental risks of these types of actions are. Because it’s really
hard for us to look through big mixtures of
chemicals and figure out which ones are most toxic, and
most problematic, and most in need of engineered solutions. So our themes for human actions
on synthetic chemicals– kind of wrapping up the things
we’ve talked about today– humanity, despite
cautionary tales like DDT, seems to be repeating the same
global scale chemical release experiments over and over. We take things like
DDT out of production, and we make a few simple
substitutions– like put a bromine molecule
in instead of a chlorine, and we make the same chemical
and start releasing it again. So I think we’re going to end
up learning this lesson over and over again. We don’t necessarily learn a
lot from our cautionary tales. I think if you’re an
environmental engineer, we probably have a lot of
good job security out there. I’m really confident we’re
not going to build our way out of our environmental problems. There’s also a lot of
thoughtless chemical pollution out there. We have lots of kind of
small habitual actions that individuals do. But when you scale them up to
big communities in urban areas, they end up being
really consequential and big sources of pollution
to the aquatic environment. I also want you to know that
our chemicals don’t just magically disappear when
we’re done with them. There, left behind, is
that chemical fingerprint that we can detect kind of
throughout our environment. And I think there are
some cases– we’re not sure which ones yet–
but there are some cases where we’re going to expect some
costly unintended consequences arising from that pervasive
discharge of chemicals out to the environment. So we have a lot of work to
do to try and maybe head off some of those
unintended consequences before they happen. Our big challenge as
a research community is understanding which
few chemicals are toxic. Probably 95%, 98%– maybe
even more than 99%– are probably totally safe
for humans and ecosystems. But there’s a few
bad actors in there, and we really need
capabilities to sort through our synthetic
chemical mixture and find out which ones
are the real problems. When it comes to water,
ecosystem impacts are definitely more
immediate and concerning. You’re a tiny little
fish, egg in water. You’re immersed in
water all the time. You have no liver–
no capability to detoxify chemicals. You have a real problem a
trace chemical exposures. There are all these
synthetic compounds we’re putting out
in the environment. If you’re a big human,
right– there’s 7 billion of us on Earth, we
have good livers– we can manage chemicals,
I think, a little more effectively than
aquatic organisms. So really, these
ecosystem impacts are kind of the place
where all the action is happening when thinking about
synthetic chemicals in water. And finally, chemical production
drives environmental release. Maybe if you’re concerned
about chemical production, or chemical burden, or your
exposures to chemicals, you should think about what
you’re do and use at home. That’s really the place
where you’re probably exposed to the widest array
of synthetic chemicals, and maybe a place with some
unintended consequences might pop up. And finally, I put one last one
here in light of the election last week. Environmental
regulations are there to maintain our health
and quality of life. And that’s something
we shouldn’t forget. It’s really easy for us,
if we travel overseas and we visit places that have
lax environmental regulations, or really don’t enforce our
environmental regulations, or don’t really care what they
destroy the environment– it’s easy to see, for the people
in ecosystems in those places, that they have a
distinctly different health profile and quality
of life relative to places that do use strong
environmental regulation. So think carefully
about what we’re going to do in this arena
over the next few years. We might have some
opportunities to get a little excited about our
environmental regulations in the next few years. A few acknowledgements–
I’d really like to thank all my
collaborators in my research group. These are all my
current students here at U-Dub– either U-Dub
Seattle or U-Dub Tacoma. I’d like to thank the National
Science Foundation, the USDA, and the EPA, for funding– as
well as a few other funding agencies. And I’d especially
like to thank the U-Dub College of Engineering,
the U-Dub Tacoma Division of Science
and Mathematics, and the Center for Urban Waters,
which are all places where I do lots of work. So that’s what I have today. Thank you for coming. If you have any questions,
please let me know.

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