Date post: | 17-Dec-2015 |
Category: |
Documents |
Upload: | stuart-douglas |
View: | 214 times |
Download: | 1 times |
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
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+
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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.
I. Odnevall Wallinder, Div. Corrosion Science, KTH
Metallic alloys possess totally different physical, mechanical and chemical properties
compared to their pure metal constituents.
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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]
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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+
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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.
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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.
I. Odnevall Wallinder, Div. Corrosion Science, KTH
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+)
I. Odnevall Wallinder, Div. Corrosion Science, KTH
National and international collaboration.