Patina formation and diffuse dispersion of alloying metals from weathering steels at urban atmospheric conditions—A combined laboratory and field investigation

The increasing use of weathering steels (WS) has raised concerns regarding the diffuse emission of alloying elements. This research paper investigates the release of iron (Fe) and the alloying elements (Cr), copper (Cu), manganese (Mn) and nickel (Ni) from two commercially available WS at urban field conditions in Stockholm, Sweden, during 1 year and in the laboratory at simulated urban conditions. The amount of released metals is evaluated and compared with recommended levels of metals in drinking water and the formation and evolution of the protective patina is studied in parallel to assess the influence on the metal release process. Only minor amounts of the alloying elements are released and is only linked to the outermost surface composition of the patina during the very beginning of the exposure. The released amounts are found to be lower compared with the corresponding levels recommended by the World Health Organisation for drinking water. The released amount of alloying constituents from weathering steels exposed to urban atmospheric conditions is below the corresponding limits of the drinking water guidelines recommended by the World Health Organisation.