『Abstract
Trace element (TE) distribution and mobility were monitored in
a typical profile of Mediterranean red soil massively amended
with phosphate fertilizers (PFs), over a period of 15 months.
Samples of soil (across a depth of 55 cm) and entire plants (roots
and shoots), collected at different points in time, an addition
to PF samples, were analyzed for TEs (Cu, Cd, Zn, and Pb) concentrations,
sequentially extracted, and examined under a Scanning Electron
Microscopy (SEM) coupled with an Energy Dispersive X-ray Spectrometer
(EDX). Results showed peaks in TE mean concentrations (Cu: 43.13,
Cd: 0.52, Zn: 116.36, and Pb:14.92 mg kg-1) in the
soil profile 4 months following PF application, but they did not
reach harmful levels. Sequential extractions revealed that the
studied TEs were transferred from residual to exchangeable fractions
in the amended soil profile (except for Cs), which may consequently
lead to their transfer to the saturated zone. The order of TE
mobility was: Zn>Cd>Cu>Pb. Amended-soil plants, Cichorium intybus
L, accumulated higher TE concentrations (Cu: 9.67, Cd: 0.37; Zn:
13.81, and Pb: 2.58 mg kg-1) than the reference plants,
but they remained within normal reported levels for plants (Cu:
3-30, Cd: 0.5-1.0. Zn: 15-150, and Pb: 2-5 mg kg-1).
Soil-plant transfer factor was notably affected by PF application,
with highest acquired values being for Cd. Evidence of fluorine
presence was detected by SEM in the amended soil, which should
be a matter of concern in PF application.
Keywords: Trace elements; Phosphate fertilizers; Soil amendment;
Mobility; Trace element uptake; Transfer factor』
1. Introduction
2. Materials and method
2.1. Field survey and soil sampling
2.2. Sample preparation and analytical methods
2.2.1. Soil pH
2.2.2. Soil and PF total concentrations
2.2.3. Vegetation analysis
2.2.4. Speciation of soil and PF samples
2.3. Mineralogical analysis
2.4. Statistical analysis
3. Results and discussion
3.1. Soil background values: reference parcel
3.2. Characterization of PF amendment
3.3. Variation of total concentrations in the soil profile
3.4. Metals mobility in soil
3.4.1. Cd speciation
3.4.2. Pb speciation
3.4.3. Zn speciation
3.4.4. Cu speciation
3.4.5. Cu, Pb and Zn versus Cd
3.5. TEs concentration in plants
3.6. TE mobility comparison
3.7. Mineral phases
4. Conclusion
Acknowledgments
References