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| Titel |
Heavy metal input to agricultural soils from irrigation with treated wastewater: Insight from Pb isotopes |
| VerfasserIn |
Wolfram Kloppmann, Lise Cary, Georgios Psarras, Nicolas Surdyk, Kostas Chartzoulakis, Marie Pettenati, Laure Maton |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036011
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| Zusammenfassung |
| A major objective of the EU FP6 project SAFIR was to overcome certain drawbacks of
wastewater reuse through the development of a new irrigation technology combining
small-scale modular water treatment plants on farm level and improved irrigation hardware,
in the aim to lower the risks related to low quality water and to increase water use
efficiency. This innovative technology was tested in several hydro-climatic contexts
(Crete, Italy, Serbia, China) on experimental irrigated tomato and potato fields.
Here we present the heavy metal variations in soil after medium-term (3 irrigation
seasons from 2006-2008) use of treated municipal wastewater with a special focus on
lead and lead isotope signatures. The experimental site is located in Chania, Crete.
A matrix of plots were irrigated, combining different water qualities (secondary,
primary treated wastewater, tap water, partially spiked with heavy metals, going
through newly developed tertiary treatment systems) with different irrigation strategies
(surface and subsurface drip irrigation combined with full irrigation and partial root
drying).
In order to assess small scale heavy metal distribution around a drip emitter, Pb isotope
tracing was used, combined with selective extraction. The sampling for Pb isotope
fingerprinting was performed after the 3rd season of ww-irrigation on a lateral profile from a
drip irrigator (half distance between drip lines, i.e. 50cm) and three depth intervals
(0-10, 10-20, 20-40 cm). These samples were lixiviated through a 3 step selective
extraction procedure giving rise to the bio-accessible, mobile and residual fraction:
CaCl2/NaNO3 (bio-accessible fraction), DPTA (mobile fraction), total acid attack (residual
fraction). Those samples were analysed for trace elements (including heavy metals)
and major inorganic compounds by ICP-MS. The extracted fractions were then
analysed by Thermal Ionisation Mass Spectrometry (TIMS) for their lead isotope
fingerprints (204Pb, 206Pb, 207Pb, 208Pb). These fingerprints allowed discriminating
geogenic (rock-derived) and anthropogenic lead fractions. Both the bulk initial soil
before any wastewater irrigation (sampled in 2006) and the residual fractions of all
analysed samples have a typical signature of uncontaminated background soils (Erel
et al., 1997 and references therein). Mobile fractions fall on a mixing line with
an endmember comparable to Israeli aerosols, themselves dominated by gasoline
lead (Erel et al., 2006). Due to labour, this signature can be found throughout the
root zone. This shift from background values can be explained by the proximity
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