Agriculture Reference
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soil nature (Luvisol) with a dominance of swelling-shrinking clays and iron oxides, which
agrees with the findings of previous works (Darwish et al. 1988; Lamouroux et al. 1968;
Sayegh et al. 1990). In addition, Cu was accumulated in the oxidizable fraction (F4) (20%), in
agreement with other findings reported in the literature (Kuo et al. 1983; Zaccone et al. 2007).
Characterization of Amendment Product
PF and PG Amendment
XRD results of PF showed that the main peak recorded in the diffractogram was calcium
phosphate (Ca (H
2
PO
4
)
2
•H
2
O) and to less extent Anhydrite (CaSO
4
). The presence of CaSO
4
in PF is the result of the acidulation of phosphate rock with H
2
O and H
2
SO
4
. The PF sample
showed an acidic pH value of 2.63 ± 0.8. As for PG, XRD results showed that the main peak
recorded in the diffractogram was Gypsum (CaSO
4
.2H
2
O) and to a less extent Bassanite
(CaSO
4
·1/2H
2
O) and Anhydrite (CaSO
4
). The measured pH value of 6.51 ± 0.5 showed slight
acidity of the PG sample.
TEM elemental mapping of PF showed particles of phosphorus, sulfur and calcium. Ca
was associated with sulfur (Ca/S=1) and with phosphorus (Ca/P=0.5). Particles of gypsum
(CaSO
4
) and acidulated P-fertilizers (Ca (H
2
PO
4
)
2
) were thus identified.
The total concentration of the studied elements (Cu, Zn, Pb and Cd) in the Lebanese
manufactured PF showed that Zn was the most abundant TE (199.3 mg kg
-1
), with the lowest
concentration being for Pb (2.66 mg kg
-1
). Copper and cadmium concentrations were found to
be 16.62 and 6.18 mg kg
-1
, respectively. These results were generally within the average
metal concentrations analyzed from a total of 196 European PFs (Cd, 7.4; Zn, 166; Pb, 2.9 mg
kg
-1
) (Nziguheba and Smolders 2008). The total concentration of the studied elements (Cu,
Zn, Pb and Cd) in the Lebanese manufactured PG showed that Zn was the most abundant TE
(123.60 mg kg
-1
), with the lowest concentration being for Pb (2.46 mg kg
-1
). Copper and
cadmium concentrations were found to be 5.13 and 3.44 mg kg
-1
, respectively.
Results of PF speciation showed that the studied metals (Zn, Cd, Cu, and Pb) were
mainly present in the exchangeable fraction (F1) (60%, 41.9%, 40.7% and 38%, respectively).
They were also found in the acid-soluble fraction (F2) (27.7%, 10.4%, 19% and 34.7%;
respectively). Moreover, part of these TEs mass (27% and 23.6% for Pb and Cd; respectively)
was bound with reducible fraction (F3). According to the sequential extractions of TEs in PG,
however, results of PG speciation showed that the studied metals (Pb, Cu, Zn and Cd) were
generally present inside the gypsum lattice (F2) (30%, 47%, 28% and 54%; respectively).
Moreover, part of these TEs mass (30, 18, and 32% for Zn, Pb and Cu; respectively) was
bound with organic matter (F4) incorporated within the PG. In addition, Pb was also found in
the residual fraction (F5) (46%), Cd in the reducible fraction (F3) (20%) and Zn in silica
fraction (F5) (36%).
Variation of Total Concentrations in Soil Profile
To analyze the PG or PF originated TEs transfer in soil with time, the concentrations of
Cd, Zn, Pb, and Cu, in different soil horizons were plotted against time for the reference
parcel R at T0 and incubated parcels PG1, PG2, PG3, PF1, PF2 and PF3 (corresponding to
T1=5-, T2=12- and T3=16-month period for PG amendment; T1=4, T2=11 and T3=15
month period for PF amendment). The time axis was started at the date when the PG or PF
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