Soil and Water Lead ContaminationFrom Flint to New York City

Benjamín Carlos Bostick and Ezazul Haque

Columbia University’s Lamont-Doherty Earth Observatory

School of International and Public Affairs

University of Iowa Superfund Research Program

Predicting Lead Content of Urban Soils: Using the history of lead fluxes to approximate lead inventory

NIEHS Presentation:

Seo Jeong Choi, Alondra Cruz, Jozef Hernandez, Abeera Saeed, Zachary Quoidbach, Shanon Dempster, Samantha Gordon, Robert Newton, Benjamin Bostick

AGU Presentation:

Mamadou Diallo, Dallas Abbott, and Benjamin Bostick

Tap Water in Flint Michigan

http://www.dogonews.com/2016/1/20/the-water-crisis-in-flint-michigan

Blood Lead in Flint

• Lead exposure is often estimated using the concentration of lead in blood. “Safe” is currently defined as 5 µg Pb/dL

• Comparison of Elevated Blood Lead Level Percentage, Before (Pre) and After (Post) Water Source Change From Detroit-Supplied Lake Huron Water to the Flint River: Flint, MI, 2013 and 2015.

• Source: Mona Hanna-Attisha, Jenny LaChance, Richard Casey Sadler, and Allison ChampneySchnepp. Elevated Blood Lead Levels in Children Associated With the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public Health Response. American Journal of Public Health: February 2016, Vol. 106, No. 2, pp. 283-290.

• doi: 10.2105/AJPH.2015.303003

Problem Statement

• The incidence of blood lead (Pb) levels have doubled in Flint, Michigan since the city changed from using Lake Huron, to Flint River water.

• Why?

• What can geochemistry tell us about the problem?

• How can we use geochemistry to solve environmental problems?

Hypotheses

• Blood lead levels increase due to increased lead exposure.

• The increase in lead exposure coincides with a change in the water supply, and an increase in tap water lead concentrations.• The lead is from lead in pipes, particularly in lead solders and joints.

• Pipes contain lead because they are older buildings and there is little new development.

• A change in water chemistry has enhanced the release of this Pb.

• The change in Pb released from pipes was predictable using geochemistry.

• There are straightforward changes to both infrastructure and water composition that would solve (or would have prevented this problem).

Water Sources:

Lake Huron

• Very large

• Clean water (mostly)

• Used by Detroit, where Flint bought water until a year or so ago

• No Pb in the water

Flint River

• Less clean (smaller), in particular organic and bacterial wastes are common

• Used for last year during an upgrade of the water system

• No Pb in the water

• Lower pH

Outcome of different sources

Flint River vs. Lake Huron

Connection to Population and Development

• Much of Flint is in decay, much lower water use, fewer people, little growth, lots of old buildings with old (lead-containing) infrastructure)

• New growth is largely free of Pb, although it can be built on contaminated land.

Lead in pipes

http://aclumich.org/article/groups-file-federal-lawsuit-secure-safe-drinking-water-flint

Lead in Pipes

• Lead in pipes is released in both dissolved and particulate forms.

pH of water supply

Lead in pipes

• Iron and lead metal are unstable in water.

• It rusts into:• PbCO3 and carbonate hydrates• Pb(OH)2

• Pb5(PO4)3(OH,F) or related compounds (some mixed phosphate-carbonates.

• These minerals are usually insoluble and coat the pipes.

• If the pH drops, then most of them become more soluble, releasing Pb into solution. Particles, some of which are rich in lead, also are mobilized by pH change.

• Chloride enhances rusting, and introduces more Pb oxidation into pipes.• PbCl2(aq) complexes soluble• Makes iron rust form much more readily as well.• Choride also destabilizes mineral colloids and causes them to be released into solution.

Solutions to Lead Water Contamination

• Adding phosphate to the water (as is done in many cities, like NYC), increasing pH, and lowing chloride levels all will stabilize Pb in the pipes.• Good for lowering drinking water exposure.

• It does not remove the Pb from the pipes.

• It does not prevent future risks of contamination within the home.

Blood Lead levels

• Blood lead levels are commonly measured as a means of measuring the exposure of an individual to lead, which is present in blood.

• Facts: blood lead levels are routinely measured in subsamples of the population.

• 2% of people in Flint have blood levels above the target level of 5 ug/dL.

• Following a change in water supply, this number increased to 4%. This is still lower than many cities in the US.

• This is a doubling, but is not very statistically significant (the total number of children with positive tests in the study were 5, when there were 4% detected).

Major Contributions to Blood Lead

• Water, Soil and Dust (aerosols) all can contribute Pb to blood.

• Based on Flint studies, we would assume that water was usually a major source of Pb to people, but we would be wrong. In Flint, and most other cities, Pb contamination in soil that is ingested or breathed is usually the major source of Pb to people.

• Soil is often contaminated by fossil fuel burning (Pb used to be added to gasoline), waste incineration, and from waste materials such as dusts from old painted surfaces that contain leaded paint or other Pbsouces.

Soil Lead levels in New Orleans

Lead levels in NYC

• Most every city has high Pblevels, particularly older cities, places where lots of burning occurred or near highways etc.

• This influences blood lead levels.

Cheng et al., (2015) Soil Science.

Population of New York

http://gizmodo.com/the-exact-age-of- almost-every-building-in-nyc-in-one-m-1348558392

Why does the age of a building affect soil Pb?Deposition of Pb over time reflects both sources, and persists.

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TEPb (10^6 ton/y)

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Pb accumulation rate(ug Pb/cm2 /y

MSW Incin.(103 tons/yr)

Blood Lead in NYC

• More here

http://www.nyc.gov/html/doh/downloads/pdf/lead/figures-complete.pdf

Blood Pb in NYC

• 10 ug//dL standard

• More than double as many people have more than the 5 ug/dLstandard

Neighborhoods and Pb

• Many NYC neighborhoods havee much higher blood Pblevels than Flint

• It is not from the water. It is from soil.

Pb in blood by NYC neighborhood

NYC Soil Pb-environmental soil samples

NYC Soil lead concentrations

Lead concentrations change in time because of changes in deposition of lead from the atmosphere in the past.

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Lead Concentration (ppm)D

ep

th (

cm)

Iron concentration (ppm)

Piermont Sediment Core: Lead and Iron concentration as a function of depth

Fe

NYC Soil lead fluxes

• Both histories show two clear

peaks in lead deposition rate.

This shows the trends in

atmospheric deposition was

similar for both locations,

while Piermont marsh had

less deposition as it was

further away from the city,

and returns to baseline more

rapidly than does NYC upon

enacting pollution controls.

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Pb

flu

x (m

g/c

m2

/y)

Year

Pb flux as a function of year: Comparison of NYC lead flux and Piermont New York lead fluxes over

time

Piermont Marsh LeadFlux

Central Park Lead FLux

NYC Soil lead inventories

Integrate soil Pb flux of the Central Park Core (Chillrud et al., 1999).

Error bars (and dotted lines for the flux) indicate representative sampling variation, and are much larger than analytical error. There is a strong correlation between the lead inventory of soil samples and the integrated lead flux of the core.

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ad In

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tory

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x (u

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NYC Soil Pb inventories (amount of Pb in soils) as a function of building construction year:

Central Park Core

Construction Year

NYC soil lead risks

Building ages (colored) reflect minimum soil lead inventories. They do not completely reflect risks because lead concentrations at the surface are affected by building renovations etc. Other sources of lead would be additional to these.

EC Soil Lead Maps• A number of soil

samples are high in lead.

a) Lead in soil

Figure 1: Maps showing soil concentrationof lead (a) and arsenic (b) in East Chicagofield site in proximity to participants in thecohort of the AESOP study. The legend,shown on the left corner of each map,

EC Soil Arsenic Maps• A number of soil

samples are high in lead.

Figure 1: Maps showing soilconcentration of lead (a) andarsenic (b) in East Chicago fieldsite in proximity to participantsin the cohort of the AESOPstudy. The legend, shown onthe left corner of each map,

b) Arsenic in soil

Bunker Hill Site, Idaho

Old CDC screening level

Old CDC screening level

EPA Action level

New CDC screening level

EPA Action level

Are Soils Safe?

• FRACTIONS BASED ON OLD ACTION LEVELS.• A large fraction of soils in East Chicago, not just in zones close to the

Superfund site, exceed recommended soil lead level thresholds. Other elements, like arsenic, are also often too high.

% o

f sa

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exce

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EPA

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il sc

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vels

Future Activities in East Chicago

Science Goals

• Measuring the concentration and the form (speciation) of lead and other contaminants in soil, dust and paint.

• Develop map tools that accurately predict exposures of metals to the population

• Looking at the effects of combined contaminants, like lead and PCBs, on health outcomes

Community Activities

• Community-based science and measurement, where you the community own the data and determine how it is used.

• Expertise in interpreting science issues that are pressing in East Chicago

• Develop practical solutions that minimize environmental contamination.

• Listen and respond to community interests. We would like you to help shape our efforts.

NYC: Very high blood lead by race

• Whites are somewhat less at risk as a whole (not in all areas).

• Asians have the highest increase (17/11) in rate of high blood lead levels. Arican-Americans are slightly higher in ovrall increase in risk of Pb exposure.

What controls the amount of Soil Pb, and potentially the risks of that lead to the population

• Hypothesis: the historical emissions of lead is a major source, but not the only source of Pb to soils.

• Hypothesis 2: The chemical form of Pb in emissions is different from that in paint and/or smelters. The current forms are altered from their original forms, and in most cases that renders them less toxic.

• The left shows the location of

Piermont Marsh relative to the

NYC area.

• Below is a map of building ages

used (not adjusted for renovation

)

Depth and Pb concentration

Pb increases in concentration with depth to a maximum and then decreases as depth increases further to about 50-70 cm. This coincides with human Pb emissions interval.

Age: determined by sedimentation rate (or sed. Rate constrained by measuring ages of soils at different depths

Conc. Converted to flux with density of the soil to account for variation in the amount of Pb that is deposited on the soil.

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Lead Concentration (ppm)

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pth

(cm

)

Iron concentration (ppm)

Figure 1. Piermont Sediment Core: Lead and Iron

concentration as a function of depth

Fe

Calculations: Age of soil (constant sedimentation rate)

Measurements taken: depth interval of bottom and top (cm), concentration of Pb (𝐶𝑃𝑏 inμg

g)

Givens/Assumed: sediment deposition (𝑠𝑑) (cm/y), density (ρ) (g/cm3)

Average depth interval d in cm =top of interval + bottom of interval

2

Age of soil ad in years =∆𝑑

𝑠𝑑+ previous age Year sample coresponds to (yd in years) =

2017 − ad

Calculations: Flux of Pb

Volume V in cm3 = ∆𝑑 × 1𝑐𝑚 × 1𝑐𝑚

Sediment accumulation 𝑠𝑎 ing

cm2 ∙ y=

ρ × V

∆yd

Year interval 𝑦𝑖 in years =𝑉

𝑠𝑑

Pb flux 𝑓𝑃𝑏 inμg

cm2 ∙ y= 𝐶 × 𝑠𝑎

Integrated Pb flux 𝑓𝑃𝑏,𝑖𝑛𝑡 in μg =

𝑡=0

t

𝐶𝑃𝑏,𝑖𝑛𝑡 𝑡 × 𝑠𝑎(𝑡)

Calculated lead fluxes

• Pb flux increased to maxima at 1940 and 1970, but were over background for most of its time.

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Pb

flu

x (m

g/c

m2

/y)

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Pb flux as a function of year: Comparison of NYC lead flux and Piermont New York lead fluxes over time

Piermont Marsh Lead Flux

Central Park Lead FLux

Inventory and Piermont Marsh

• Total Pb inventory increases with soil age

• Soil age is roughly a linear function over the duration of Pb inputs, but probably not over longer timescales.

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ad In

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Soil Pb inventories as a function of building construction year:

Comparison of soil Pb inventories and Integrated lead fluxes determined using Piermont Marsh core

Marsh Core

Marsh PushCores

Soil Inventory and Age• Older soils have

more Pb

• Amount of Age is predictable using Pb fluxes from cores, and the age of the construction a the site.

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Soil Pb inventories as a function of building construction year:

Comparison of soil Pb inventories and Integrated lead fluxes determined using Central Park core

Central Park Core

Construction Year

Surface Soil Concentration and Pb Inventory

• Not a strong relationship between the surface soil concentration and the total amount of Pb in the soil (inventory)

• Why: mixing? Erosion? Physical processes.

y = 0.0132x + 88.54R² = 0.198

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Pb inventory (ug/cm2)

Relationship between Surface concentration of lead in comparison with the Measured Pb inventory in

NYC soils

Hudson River Cores• Graphs showing Pb

and As concentrations in ppm versus depth in cm.

• No subsurface Pb peak due to mixing, all of the sediments in the top 60 cm were of similar age (about 50 y on average). MIXING.

Conclusions

• This method works to predict Pb inventory, but not the surface Pb concentration, in soils from urban areas.

• There are other sources that could contribute additional Pb to the system, or that focus Pb emissions, that also add additional Pb.

• The chemical form of Pb is these soils is highly variable, and the risks posed by Pb thus really need to know what these chemical forms are, to properly determine the risks of Pb exposure.