Metals and alloys in external constructions – changes in speciation and bioavailability of corrosion-induced metal runoff upon environmental entry. Associate

Metals and alloys in external constructions Metals and alloys in external constructions – – changes in speciation and bioavailability of changes in speciation and bioavailability of

corrosion-induced metal runoff upon corrosion-induced metal runoff upon environmental entry.environmental entry.

Associate Professor I. Odnevall Wallinder, Ph.D. S. Bertling, J. Sandberg, G.Herting, K. Midander, B.Bahar, C. Leygraf

Div. Corrosion Science, KTH, Stockholm, Sweden

www.corrosionscience.se

MITF seminar, Stockholm, Oct. 18, 2007

http://www.corrosionscience.se/

The diffuse dispersion of metals in the societyhas many sources.

I. Odnevall Wallinder, Div. Corrosion Science, KTH

No material is inert! All metals/alloys interact with the environment.

SO2

Metal runoff/release

Me, Men+


metals / alloys

surface treatment organic

coatings

patina

0

1

2

3

4

Rat

e / µ

m y

r-11 2 3 4 5 6 70

CORROSION

RUNOFF

Ex. copper sheeturban site

Exposure period / years

Corrosion and runoff are totally different processes that occur independent of each other.


Metallic alloys possess totally different physical, mechanical and chemical properties

compared to their pure metal constituents.


Pure metals

Fe Fe

SteelCr

Fe

Metal alloys

Stainless steel

The proportion of released alloy constituents is usually significantly different from the

bulk composition.

Fe

Ni

Bulk alloy

Cr

Fe

Cr Ni

Metal release

stainless steel

oxide


The generation of accurate exposure assessment data is essential for reliable

effect- and environmental risk assessment.

Exposure assessment:Exposure assessment:Metal runoff rates

Corrosion ratesExposure parameter values

Effect assessment:Effect assessment:Metal chemical speciation

BioavailabilityEcotoxicity effects

Risk assessment, risk management

Legislations, restrictionsI. Odnevall Wallinder, Div. Corrosion Science, KTH

Zinc and zinc-based alloyswith and without surface

treatments or coatings

Stainless steelCopper and

copper-based alloys

Cu, Zn, Fe, Cr, Ni, Al, Sn….Cu, Zn, Fe, Cr, Ni, Al, Sn….

Metal runoff –urban field studyNaturally patinated copper – 10 years

Zinc-based materials – 9 yearsStainless steel – 4 years

Commercially available materialsAnnual runoff rates

Metal concentrations in runoff water Metal speciation modeling

Bioavailability towards bacteriaEcotoxicity effects on algae

Environmental interaction of metal runoff - laboratory study

Retention capacitiesChanges in metal speciation and availability

Metal concentrations in percolate water Future mobilization

Generated keyinformation for

expsosure assessment.

Me, Men+

Percolate

Recipient

Metal runoffMe, Men+

Surface retention

Metal runoff - laboratory studyRealistic simulations of rain events

Rain parameter dependenceInstantaneous runoff rates during rain events

Predictive runoff rate modeling

The runoff rate of metals, e.g. copper can be predicted for specific sites or regions.

Odnevall Wallinder et al J. Env. Monit., 9, 66-73, 2007

Effect assessment by linking generated runoff

data with the BLM model.

=(0.37.SO20.5 + 0.96.Rain.10-0.62pH).

cos(45º)

cos()Cu runoff rate [g Cutot m-2 y-1]


During environmental entry, the released metal will interact with solid surfaces already

in the near vicinity of a building.

Soil surfacesSoil surfaces

Concrete Concrete pavement, pavement, stormwaterstormwater

systemssystems

LimestoneLimestone

Inorganic, organicInorganic, organicmatter matter

Metal runoff

Me, Men+


The presence of e.g. organic matter at the immediate release situation greatly influence the

chemical speciation of released metals.

0

20

40

60

80

100

Pollen

No pollen

Fra

ctio

n C

u(H

2O) 62+

/ %

BioavailableCu-fraction Urban site

BioavailableCu-fraction

Marine site


Soil shows a high capacity to retain released metals. Measured metal concentrations in the percolate water are below the ecotoxic endpoint for algae.

Runoff water e.g. Zn

100% bioavailable

Metal runoff

Me, Men+

Zntot < EbC50

Backgroundconcentration

0

20

40

60

80

100 Zn2+

Znorg

Znother Zin

c sp

ecie

s %

95-100% SOIL interaction


Concrete acts as a sink for metal release and show a high capacity to reduce

the bioavailability of the released metal, e.g. copper.

8-40% bioavailable

copper

FICTIVESCENARIO

0

2.10-6

0 20 40 60 80 100 120

Cu2+

con

cent

rati

on /

g L

-1

distance in storm drain / m

1.5.10-6

1.10-6

5.10-7

Metal runoff

100% bioavailablecopper

CONCRETE

2.5 m


10-40% of released copper retained

The runoff water is considerably diluted with other water sources during environmental entry,

which reduces the total metal concentration and changes its chemical form.


Essential to compare corrosion-induced metal release with other sources of metal dispersion,

e.g. copper in Stockholm, Sweden.

Tap water systems:4 300 kg year-1

Buildings and externalapplications: 650 kg year-1

Traffic: 5 700 kg year-1


Hea

lth

Concentration of essential metal (Cu, Zn Fe...)

Optimum windowfor good health

Deficiency Toxic excess

Metal toxicity depends on chemicalform, compound, dose, etc.

Essential metals

Heavy metals60 elements

Light metals 14 elements

TiAu

W Ag

NiSn

FeZn

Cu

MnCr Na K

MgCa

PbHg

Cd Be

Al

Li

Ba

> 4.5 gcm-3 >Cs

CuThe definition ”heavy metal”

has nothing to dowith toxicity.


The total metal runoff is not a measure of potential adverse environmental effects. Chemical speciation

and bioavailability must be considered.

Corrosion & Wear

Complex Compound Ion(Zn-EDTA) (Zn4SO4(OH)6) (Zn(H2O)6

2+)

Mineral

Metal extraction

Metal

Mineralization

Immobilization

(Cu-EDTA) (Cu4SO4(OH)6) (Cu(H2O)62+)


National and international collaboration.

http://www.nipera.org/index.html

http://www.naturvardsverket.se/sv/

http://www.kuleuven.ac.be/english/

http://www.es.lancs.ac.uk/

Documents

Metals and alloys in external constructions – changes in speciation and bioavailability of corrosion-induced metal runoff upon environmental entry. Associate