Metals and alloys in external constructions – changes in speciation and bioavailability of corrosion-induced metal runoff upon 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 MITF seminar, Stockholm, Oct. 18, 2007

The diffuse dispersion of metals in the society has many sources. I. Odnevall Wallinder, Div. Corrosion Science, KTH

No material is inert! All metals/alloys interact with the environment. SO 2 Metal runoff/release Me, Me n+ I. Odnevall Wallinder, Div. Corrosion Science, KTH

metals / alloys surface treatment organic coatings patina  Rate / µm yr CORROSION RUNOFF Ex. copper sheet urban 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 Steel Cr 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 CrNi 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: Metal runoff rates Corrosion rates Exposure parameter values Effect assessment: Metal chemical speciation Bioavailability Ecotoxicity effects Risk assessment, risk management Legislations, restrictions I. Odnevall Wallinder, Div. Corrosion Science, KTH Zinc and zinc-based alloys with and without surface treatments or coatings Stainless steel Copper and copper-based alloys Cu, Zn, Fe, Cr, Ni, Al, Sn….

Metal runoff –urban field study Naturally patinated copper – 10 years Zinc-based materials – 9 years Stainless steel – 4 years Commercially available materials Annual runoff rates Metal concentrations in runoff water Metal speciation modeling Bioavailability towards bacteria Ecotoxicity effects on algae Environmental interaction of metal runoff - laboratory study Retention capacities Changes in metal speciation and availability Metal concentrations in percolate water Future mobilization Generated key information for expsosure assessment. Me, Me n+ Percolate Recipient Metal runoff Me, Me n+ Surface retention Metal runoff - laboratory study Realistic simulations of rain events Rain parameter dependence Instantaneous 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. =( SO Rain pH ). cos(45º) cos(  ) Cu runoff rate [g Cu tot 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 surfaces Concretepavement,stormwatersystems Limestone Inorganic, organic matter Metal runoff Me, Me n+ 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 Pollen No pollen Fraction Cu(H 2 O) 6 2+ / % Bioavailable Cu-fraction Urban site Bioavailable Cu-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, Me n+ Zn tot < EbC 50 Background concentration Zn 2+ Zn org Zn other Zinc species % % 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 FICTIVE SCENARIO Cu 2+ concentration / g L -1 distance in storm drain / m Metal runoff 100% bioavailable copper 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: kg year -1 Buildings and external applications: 650 kg year -1 Traffic: kg year -1 I. Odnevall Wallinder, Div. Corrosion Science, KTH

Health Concentration of essential metal (Cu, Zn Fe...) Optimum window for good health DeficiencyToxic excess Metal toxicity depends on chemical form, compound, dose, etc. Essential metals Heavy metals 60 elements Light metals 14 elements Ti Au W Ag Ni Sn Fe Zn Cu Mn Cr Na K Mg Ca Pb Hg Cd Be Al Li Ba > 4.5 gcm -3 > Cs Cu The definition ”heavy metal” has nothing to do with 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) (Zn 4 SO 4 (OH) 6 ) (Zn(H 2 O) 6 2+ ) Mineral Metal extraction Metal Mineralization Immobilization (Cu-EDTA) (Cu 4 SO 4 (OH) 6 ) (Cu(H 2 O) 6 2+ ) I. Odnevall Wallinder, Div. Corrosion Science, KTH

National and international collaboration.