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| Titel |
Effective radium concentration of lead-contaminated topsoils |
| VerfasserIn |
Frédéric Girault, Frédéric Perrier, Charles Poitou, Francis Douay, Hervé Theveniaut, Valérie Laperche, Laurent Bollinger |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093676
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| Publikation (Nr.) |
 EGU/EGU2014-8628.pdf |
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| Zusammenfassung |
| As the global amount of topsoil is decreasing and its importance for agricultural purposes is
increasing, the detection and quantification of metallic pollutions in topsoils has become a
topical concern of the utmost importance. Radium, which is generally concentrated in metal
oxides and hydroxides and relatively easily leached from rock and soil, could potentially give
precious information about the extent of the pollution at large spatial scales. In this study, the
radon source term (effective radium concentration, ECRa) of more than 300 topsoils
from a lead-contaminated site in the North of France has been measured using the
accumulation technique. After placing the sample in a container, sampling of the air is done
using a scintillation flask after some accumulation time. Radon concentration in
the flask is inferred from counting in a photomultiplier 3.5 h after sampling, from
which the effective radium concentration (ECRa) of the soil sample is calculated,
expressed in Bq kg-1. This technique allows the measurement of large numbers
of samples. The ECRa results of the topsoils, obtained over ca. 800 km2, show
remarkable spatial organization and the values are compared with the results of their
chemical analyses performed at ISA (Lille, France) and BRGM (Orléans, France).
The highly lead-contaminated zone (with Pb concentrations larger than 250 ppm)
is also relatively well circumscribed using ECRa apart. Indeed, ECRa values of
topsoils are larger in the contaminated area than outside, compared with the average
regional ECRa value. The mapping of ECRa of topsoils at large spatial scale appears
therefore as an important asset to characterize this polluted area. Our ECRa data are
also compared with the low-field specific magnetic susceptibility (Ïm) and other
magnetic parameters to infer some insights from the magnetic fabrics in the soil and the
ECRa–Ïm relations. Relations between ECRa and others metallic elements (Cr, Co, Hg,
Ag) or others intrinsic characteristics (amount of sand, silt, organic matter) of the
topsoils are also provided. ECRa appears as a powerful parameter to characterize the
spatial structure of soils, and in addition provides clues on the susceptibility to
heavy metal contamination. This study opens some interesting perspectives for the
understanding of the relation between radium and heavy metals in the environment. |
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