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| Titel |
Magnetic tracing of coal slag and ash in a river basin |
| VerfasserIn |
Erwin Appel, Stanislav Frančišković-Bilinski, Qi Zhang, Wolfgang Rösler, Qian Zhang |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128485
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| Publikation (Nr.) |
 EGU/EGU2016-8475.pdf |
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| Zusammenfassung |
| Atmospheric distribution of pollutants by magnetic means has been extensively studied, but
only little is known about pollution-related magnetic signatures for aquatic transport. The
case of a textile factory in Croatia that released heavy-metal polluted and highly magnetic ash
and slag material from coal burning into Mrežnica River for 110 years (1884-1994)
represents an ideal target for studying principles of magnetic tracing through a river
system. Samples from the riverside close to the factory show high concentrations of
magnetite (mass-specific susceptibility χ ∼1-4 x10−5 m3kg−1) with low frequency
dependence (χfd% <3%). However, quantitative detection of slag and ash transport in
the downstream direction through the riverbed is hindered by extremely variable
magnetic properties of the river sediments, presumably due to hydrodynamic sorting.
Surface mapping of χ on riverbanks ∼3 km downstream of the factory reveals clear
evidence for substantial distribution of slag and ash materials in the river basin due to
flooding; the affected area reaches to >100 m from the riverside. The spatial pattern of
shallow vertical sections of χ (surface to ∼0.5 m depth) shows different layers of coal
burning residues which may even allow discriminating different flooding events
(historical flooding). In order to assess the possible influence of fly ash from the
factory, we studied vertical soil profiles at locations which cannot be reached by
floods. These (red) soils, formed on limestones, are strongly magnetic (χ >10−6
m3kg−1). Despite this strong natural magnetic signals, the depth dependence of χfd%
and characteristic chemical properties (sulfur content, Ni/Cu ratio) as well as the
dependence of the vertical χ distribution with distance to the point source indicate a
contribution of fly ash to soil contamination near the factory (within about one
kilometer). The presently available results indicate that with a strong magnetic point
source as in the case of the studied textile factory, magnetic tracing can contribute
important information on the transport and mass balance of sediments in a river basin. |
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