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| Titel |
Relationships between magnetic parameters, chemical composition and clay minerals of topsoils near Coimbra, central Portugal |
| VerfasserIn |
A. M. Lourenço, F. Rocha, C. R. Gomes |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 8 ; Nr. 12, no. 8 (2012-08-14), S.2545-2555 |
| Datensatznummer |
250011047
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| Publikation (Nr.) |
 copernicus.org/nhess-12-2545-2012.pdf |
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| Zusammenfassung |
| Magnetic measurements, mineralogical and geochemical studies were carried
out on surface soil samples in order to find possible relationships and to
obtain environmental implications. The samples were taken over a square grid
(500 × 500 m) near the city of Coimbra, in central Portugal. Mass specific
magnetic susceptibility ranges between 12.50 and 710.11 × 10−8 m3 kg−1
and isothermal magnetic remanence at 1 tesla values range
between 253 and 18 174 × 10−3 Am−1. Chemical analysis by atomic
absorption spectrometry shows that the concentration of various toxic
elements was higher than the mean background values for world soils. Higher
values of susceptibility and toxic elements content were reported near roads
and rivers. Urban pollution and road traffic emission seem to be the main
influence for these values. A semi-quantitative X-ray diffraction study has
been carried out on a representative set of subsamples, using peak areas.
Illite (average 52%), kaolinite (average 55%), chlorite (average 6%)
and irregular illite-smectite mixed-layers (average 9%) are the
major clay minerals groups identified. Mineral composition of total fraction
confirms the presence of magnetite/maghemite. The clay minerals results
point to a contrast in the behavior of the main clay minerals: illite,
chlorite, and kaolinite (also, smectite in some samples), which are
generally in agreement with the magnetic and geochemical data. The results
showed that magnetic measurements are a sensitive, fast, inexpensive and
robust method, which can be advantageously applied for studying soils
affected by urban and road pollution. |
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