Trace Element Contaminents - Paul Grossl

Thanks, Dan.

What's a biogeochemist?

Well, I look at soil chemical interactions
and how that affects,

how those chemicals are taken up by plants

and eventually how
they're transferred into the food chain.

So that's probably
the simplest way of describing it.

But anyway, welcome to my talk on, trace

element
contaminants in urban soil environments.

And before I go
on, I'd like to, acknowledge

my coauthors, Melanie
Stark and Eli Oliver.

We've been working on, soil survey
of the whole Wasatch Front,

looking at different gardens, trying
to get an idea of what the metal levels

are in these soils,
as well as organic contaminants.

And we're kind of in the midst of that.

Right now.

Also, before I go on, I should probably
define what I mean by trace elements.

They are defined as having indigenous

poppy, indigenous concentrations,

less than a hundred parts per million.

So that's either in the solid
or liquid phase.

So it's interesting.

About 15 minutes before
Dan came to my office

to ask me to present here,
in this vegetable

session, I just got done
reading an article in the New York Times.

You may have seen it where it says
some baby food may contain toxic metals.

In the U.S., and it said that,

the levels were high in
some of these foods

with arsenic, lead and cadmium.

And as I was reading that, I noticed,

carrots came up and sweet potatoes
and I thought,

and then Dan comes to my office and
I said, well, this would be totally ideal.

I could talk a little bit about what I've
found in some of these urban communities.

Also, this

is about the time of year
where a lot of you and people in general

are getting, or planning
their backyard gardens, and they may not

even be aware that there could be issues
with, some of these trace elements.

Now, the two trace elements that I'm going
to focus on are lead and arsenic,

mostly because they're EPA's two priority
priority trace element pollutants.

And what I'd like to do
is just kind of give you an idea

of why you need to be concerned
and when you need to be concerned,

an idea of what soil tests to ask for

if you are concerned,
and then some tips on gardening.

If you have soils that are a little bit
elevated in terms of, lead and arsenic.

So what are

some of the health concerns, led?

It's the most ubiquitous toxic element
in the environment.

And mostly we're concerned about it
because it

impairs cognitive development,
especially in children.

So lead poisoning is the most. Oops.

I got my, panel picture here.

So I'm going to move
that, is the most universal

and serious disease
to impact young children.

The most frequent motor poisoning arising

from ingestion of lead,

paint chips and from soil.

And, anyway, most of us, in terms
of getting sick by land,

it's 70% of it comes from food,

arsenic, the acute symptoms are vomiting.

If you ingest too much arsenic
and gastrointestinal distress.

And if those levels are high enough,
you'll start getting numbness

and tingling
in the extremities. Muscle cramps.

And eventually, if you eat enough of it,
death, long term exposure.

It's a carcinogen, causes skin lesions.

It's also associated
with cardiovascular disease and diabetes.

And, it can be linked to negative impacts

on cognitive development
and increased deaths in young adults.

Oops.

Let me go on here.

Here we go.

So let me give you an idea of what
some of the background

levels of lead and arsenic are
and what they are in urban environments.

So lead in uncontaminated surface
soils ranges

from anywhere from 20 to 20:07 p.m.

or milligrams per kilogram of soil.

In urban soil, we find that those levels

start creeping up to 150mg/kg or higher,

some cases greater than a thousand ppm.

The EPA has set a

regional screening level of 400mg/kg,

and I'm going to use that as our kind of,
action level.

And that's why I have it here in red
arsenic.

Typical background
levels are anywhere from point one

less than 0.1 to 40 PM.

Now, the regional screening
levels are all over the place

in terms of how they vary from state
to state, even within states

and municipalities as well as EPA,

if EPA is set a level of 0.39.

But we're finding that all of the soils

that we test here along the Wasatch
Front exceed that.

And, we don't start getting concerned

until that level
starts approaching 20 p.m.

or higher.

So some of the urban sources of leading

arsenic contamination,
well, lead comes from auto emissions.

It could be from former paint chips.

In the past, lead
arsenic pesticides were frequently used.

Again, if you're close to any industry

and smelters, could be a source of lead

and arsenic, as well as mining activities
and biosolids.

Or, if you're adding, composted sewage
sludge to your soil.

So when to suspect
that you may have a contaminated soil?

Well, if you live within 20ft of an older
building

and usually where that building
had been painted

at least prior to 1978,

there could be the potential of leaded
paint having been used in those paint

chips, flaking off
and entering your soil near that building.

If you live within 20ft of roadways,
parking areas, and higher traffic areas,

there's potential for lead

being accumulating in your soil
because of, well, actually,

leaded gasoline was banned in 1996,
so it hasn't been that long ago.

If you live in one mile of smelters,
fossil

fuel power plants and cement facilities,

that could be the potential for lead
and arsenic contamination of your soils.

One thing people aren't aware about

is that if there was a former orchard

on your property and that's pre 1950

lead, arsenic was the pesticide of choice
and that's probably

still in your soil. So,

you might

want to have your soil checked
if it's the case.

If you live near tailings
from current and former metal or mines,

you might want to suspect
that your lead and arsenic

levels could be elevated as well
as, again, the addition of biosolids.

Now, before I go on to talk about
some of the best management

practices, I want to just,

briefly
go over this concept of bioavailability

and how not only plant nutrients,
but how these,

contaminant trace elements
enter the food chain.

So when I talk about bioavailability, I'm
focusing here and see here's my cursor.

The soil solution so far in order

for those elements
to be taken up by a plant,

they have to be present
in the soil solution.

So some things can be more bioavailable
if it's more soluble.

Or sometimes people refer to
an element as being mobile.

So there's a constant tug of war
going on between elements

being released or retained by the soil
and entering the soil solution,

and then making their way into the plant.

So I want to introduce this concept
of the soil plant barrier.

And fortunately leading arsenic
are strongly Zoar to soil

and very little is translocated
to the edible portions of plant

despite the amount present in the soil.

So if we look at this chart here,

lead and arsenic
tend to be retained by the soil particles.

They're not very soluble or mobile,
and therefore

they're not transferring into the food
chain.

So the toxicity from food chain
transfer is low.

And when you ask

for a soil testing those values
I reported earlier,

the test you should request
is the total elemental composition.

It's EPA test 3050.

But that test actually looks at

not only the bioavailable level,
but the total orbed or retained level.

So the values that we reported here
for leading arsenic are mostly

the values of lead, arsenic
that are retained by the soil.

So it's not giving you
an indication of its bioavailability.

Excellent article came out in

2020 2015 by Sally Brown.

And I'm just going to kind of summarize it
here.

Recent studies have shown that lead
in contaminated urban garden soils

mainly existed in the carbonate fraction

complex with organic matter
or absorbed iron oxide.

So in other words, again, lead
and I think are mostly retained

by some of these soil particle surfaces.

But you need to consider that lead
entering the soils

from lead based paint from the paint chips
or from,

leaky gas tanks will generally
have higher of bioavailability.

So when you do get your soil test
and you know that it's from paint chips

or gasoline, there's probably a greater
likelihood that the levels in your plant

tissue are going
to be a little bit higher.

Okay.

Let me talk about
some of the best management practices.

Now that we know how lead and arsenic
behave in soils,

let's focus on vegetables here.

So if you at all expect

that the concentrations of lead in charge
that could be higher.

So just avoid growing
any kind of vegetable in that area.

In particular, avoid growing

root vegetables and leafy greens
because there

that's where lead arsenic
tend to be higher.

So if we're looking at lead uptake,
typically

higher levels are found in root crops.

So we're looking at carrots

beets

and they're a little bit higher than leafy

crops
like your salad greens, spinach etc..

And typically we find that very little

of the latter
arsenic is transferred into fruiting.

The edible portions of,

fruiting plants like tomatoes

or peppers, legumes,
as well as growing crops.

But it's also just a good idea,
no matter what, to wash

or peel
any soil off the vegetables before eating.

Because that's where the lead and arsenic,
if there is any,

any lead laden soil particle,
that's where they're going

to be found.

Now, on the soil side,

if your levels come out high,

the best thing to do again,
because we're trying to minimize exposure,

especially exposure to small children,
keep your soils covered.

You want to minimize exposure,
to bare soil.

What you can do is plant turf over that.

Again, it doesn't transfer so much into
the turf or the plant portion of turf.

You can grow shrubs or etc.

and in between those bare areas
add a mulch layer.

So you do want to again
avoid any exposure to the bare bare soil.

Then if your levels aren't

real high,

you can always dilute that,
those levels out by adding

a contaminant free material
so you can bring in a quality topsoil.

Make sure you test it to make sure
that the lead and arsenic levels are, low.

Before you add it,
you can add a quality compost.

Again, make sure the lead arsenic levels
are low before adding it.

And by mixing that in with,
that's why you're going to be

deluding out the concentration of lead
and arsenic in that soil.

And, and,
and also these materials will help retain

more of that lead and arsenic so
that it doesn't make its way within the,

food chain.

And of course, in severe cases,
just get a raised bed

containing materials
that, again, are free of lead in arsenic,

always, no matter what,

if you're working in a garden, thoroughly

wash your hands
after working in the garden

and before eating any,
of your vegetable crops, just to make sure

that you're not transferring any soil

bound land.

To you.

And, all.

So you don't want to attract
a lot of material into your house.

Always remove or rinse off your garden
shoes before entering the house.

So those are some best management
practices.

Now, what I'd like to do is just,
go through two examples

here, and I'll do an okay time,

that we that I've encountered
through the last year.

So if you look at, the first example, I'm

going to look at a typical backyard
vegetable garden in Salt Lake City.

And this home was built in 1903.

And then in the

second example,
I want to talk about a garden area

where we know that that was contaminated
with lead containing paint chips.

And in that contaminated area,
they're still growing

some fruit trees,
in this case, peach and fig trees.

And there's a rhubarb patch there.

So let me go through what we found
and some of the recommendations

that I gave regarding those two scenarios.

So the first one, again
is a typical backyard garden.

You saw this picture before actually,
for those of you

there in the Salt Lake area, this is just
south of I-80 off of 700 east.

So it's kind of on that edge as you're

approaching SugarHouse.

So soil samples were taken throughout,

around this house.

And again, this house was built in 1903.

And, we collected some samples.

And let me get my cursor here.

Right here
where they have the vegetable garden.

Now, we did collect these samples
before this garden was actually planted.

And, we found that again requesting that

EPA test 3050,

we found that
the lead in the soil was at 100 ppm

and arsenic was at 7 p.m..

When I looked at those results.

It's pretty typical
of what we find in residential areas is,

within urban environments.

And I wasn't too concerned.

Again, even if they grew root crops,

as long as they wash those root crops.

There
shouldn't be any concern about any lead

getting into their, food.

So my recommendation is your soil is fine
and there's no restrictions on what

you grow now and the front of the house,
and you can't see it here.

This was the front east corner.

We took some samples within 20ft of that.

And we did find that the lead levels

were slightly elevated, 200 ppm

still below that level of,

400 ppm that I showed you earlier.

And arsenic was above 20.

So it's about 20:01 p.m..

So I'm starting to get concerned here
that,

there could be some issues,
especially if they grew edible food crops.

So my recommendation was no edible food
crops.

And luckily
that they didn't intend to grow any there

anyhow. And,

my recommendation was to keep that soil
covered so, so that it wasn't bare.

And they did have shrubs
that they were planning to grow there.

They were going to incorporate mulch
in between those shrubs

and, grow turf,

around that too.

So that took care of that soil

for that area.

And then the other one was that led that,

garden that had lead contaminated

paint chips or contaminated
with lead containing paint chips.

So there the level was 580 parts
per million and arsenic was a little bit

high, is around 19 p.m..

And, they were concerned
because they had some fruit trees

growing in that within 20ft area there.

And they had a rhubarb patch.

And I called back the,

gardeners for homeowners and told them,

why don't you just send me
some of your fruit tissue?

Send me some peaches and some figs
and some rhubarb stalks

and let me analyze those
and see if you need to be concerned.

And just like I thought,
when the land and arsenic levels came back

on the peaches and the, fig fruit,
they were actually below detection.

We couldn't even pick up a signal.

And we usually find
that it just doesn't transfer up into,

especially with

fruit trees into the actual fruit.

Now, with the rhubarb, we did pick up

some lead in the stocks
at a level of 2.5 parts per million.

No arsenic was detected. So that's good.

And then I started doing some back
of the envelope calculations.

And I thought, well, how much would they
eat in a piece of pie or whatever?

So I determined,

I had some of the values there for,

FDA levels
for how much lead you can ingest.

And I thought that if they ate

a cup of that rhubarb stock, I calculate

they still would be about a thousand times

lower than the FDA provisional tolerable

total intake level,
which is 75 micrograms of lead per day.

So, and that level would be 25 micrograms
for pregnant

women and six micrograms
per day for infants and children.

So they
weren't going to eat that rhubarb anyway,

and they were going to put the patch
in a different area

where there was total contamination
from white chips.

So the so those were two typical scenarios
that, I often see.

There's one I, I'm just going to mention,

there was a homeowner
that had, bought a property,

had some on that property.

They found out
that they had some old trucks

that were leaking gasoline into the soil.

And they're the levels total are lead

levels were over a thousand.

But again, the concern was that

the available levels were high.

So that was a, scenario
that you don't see too often,

but it was one where we actually called
the state,

Department of Environmental,

quality,

and they just put a cement slab over it.

So there was no exposure at all.

Anyway,
let me just summarize the talk here.

So if you're at all concerned,

about leading arsenic contamination,

get yourself tested and use that

EPA 3050 total elemental composition.

And again, the levels
that I presented here where we start

getting concern
are if your lead levels exceed 400

ppm and your arsenic levels,

exceed 20 p.m..

Now, I just want to point out to that
arsenic level may change

as we start getting more data
from our survey.

Again, avoid growing root

crops and leafy
greens and contaminated soils.

Follow best management practices.

In other words,
you want to cover your soil,

dilute that soil.

If you do have lead nasty contamination
issues or use raised beds in severe cases,

always you wash your hands and vegetables
before eating

and rinse your soil from shoes
before entering the house.

If you're still concerned,

I recommend and you have vegetables

that you collected,
have those analyzed for trace metals,

and you'll have a better idea
of what's going on there.

Okay.

I think
let me just I think that's, Well, I.