 |
| Titel |
Chromium in urban sediment particulates: an integrated micro-chemical and XANES study |
| VerfasserIn |
Kevin Taylor, Patrick Byrne, Karen Hudson-Edwards |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107708
|
| Publikation (Nr.) |
 EGU/EGU2015-7421.pdf |
|
|
|
|
|
| Zusammenfassung |
| Chromium is generally common within the urban sediment cascade as a result of abundant
industrial and transport-related sources. The risks that Cr-bearing particles pose to
ecosystems and humans depend on the solid phase chemical speciation of Cr in the particles.
In this study, we use bulk chemical digests, sequential chemical extraction analysis, electron
microscopy, electron microprobe and microfocus XANES analysis to describe the solid-phase
speciation of Cr in urban particulate matter from both aquatic sediment and road dust
sediment (RDS) in Manchester, UK.
Cr-bearing grains within RDS are predominantly iron oxide grains, commonly of goethite
or haematite mineralogy, but Cr-bearing silicate glass grains are also present. Iron oxide glass
grains most likely have sorbed Cr, and derive from the rusting of Cr-steel particles from
vehicles. Electron microprobe analysis indicates concentrations of Cr up to 3200 μg/g in
these grains, and XANES analysis indicates that Cr(III) is the dominant oxidation state, with
some trace amounts of Cr(VI). Cr-bearing grains within aquatic sediments are dominated by
alumino-silicate glass grains derived from industrial waste. These grains contain Cr-rich
areas with up to 19% Cr2O3 and XANES analysis indicates that Cr is present as
Cr(III).
The dominance of Cr(III) in these urban particulate grains suggests limited bioavailability
or toxicity. However, the presence within two markedly different grain types (iron
oxides and silicate glasses) indicates that the long-term geochemical behaviour
and environmental risk of RDS and the aquatic sediments studied are likely to be
quite different. These findings highlight the importance of understanding sources of
metal contaminants in urban environments and the geochemical processes that
affect their transfer through the urban sediment cascade and the wider river basin. |
|
|
|
|
|
|