1. Assessment Heavy Metals (Pb, Zn, Cd) and Metalloids (Sb, As) Mobility in Carbonated Soils Contaminated by Mining Wastes (Northern Tunisia)
Yosra Achour1,2,3, Radhia Souissi1, Haifa Tlil1,3, Mikael Motelica Heino2, Fouad Souissi3
1Laboratoire des Matériaux Utiles, Institut National de Recherche et d’Analyse Physico-chimique, Pôle Technologique,
Sidi Thabet, 2020 Tunis, Tunisia
2CNRS/ISTO Institut des Sciences de la Terre d’Orléans, UMR-CNRS 7327 Campus Géosciences, 1A rue de la Férollerie, Orléans, France
3Universite´ Tunis El Manar, Faculte´ des Sciences de Tunis,2092 Tunis, Tunisia
Thursday, 22nd August 2019

2. Fig.1: Location map of the study areas
GOLDSCHMIDT 2019
Purpose of study
The main objective of this work was to study the mobility of these potentially toxic elements (PTE) in soils developed on carbonated source rocks near several abandoned mining sites in northern Tunisia (Jalta, Jebel Hallouf - Sidi Bouaouane, Jebel Ghozlane and Hammam Zriba).
Fig.1: Location map of the study areas 2

3. Physico-chemical parameters Test de lixiviation
GOLDSCHMIDT 2019
Materials & Analysis techniques
Sampling
Rhizosphere samples
Drying  
Seving (2 mm)
AFNOR 
Grinding
Physico-chemical parameters
Test de lixiviation
Extraction cinétique avec LMWOAS (pH = 2,8)
Shan et al. (2003), Wang et al. (2004), Feng et al. (2005)
1-pH
2-Conductivity
3-Carbonate rate
4-Cation Exchange Capacity
Mixture of organic acids (pH=2,8)(4/2/1/1/1)
Mineralogical
Acetic acid C2H4O2
DRX
Lactic acid C3H6O3
Citric acid monohydrate C6H8O7.H2O
Chemical analysis
ICP-AES
Malic acid C4H6O5
Formic acid CH2O2

4. 1- Physico-chemical parameters
GOLDSCHMIDT 2019
Results
1- Physico-chemical parameters
Samples
EC (µs/cm) pH
% CaCO3
CEC (meq/100g)
Jebel Hallouf
217.20
8.31
75.64
127.53
Sidi Bouaouane (Control)
237.50
7.84
39.74
Not measured
Sidi Bouaouane
499.00
7.78
46.15
424.18
Jalta
367.50
7.12
1.28
531.22
Hammam Zriba
115.40
7.69
24.36
41.78
Hammam Zriba (Control)
271.50
7.07
21.79
Jebel Ghozlane
865.50
33.33
74.97
Jebel Ghozlane (Control)
233.10
7.99
50.00
 Not measured 4

5. Sidi Bouaouane (control) Jebel Ghozlane (control)
GOLDSCHMIDT 2019
Results
2- Chemical analysis
Locality As
mg/kg Sb Pb Zn Cd
Sidi Bouaouane (control) 44
0.5
391
418 7
Sidi Bouaouane
683
145
17350
8620 64
Jebel Hallouf
669
103
10321
7951 55
Jalta
110 Nd
3061
1240 9
Jebel Ghozlane (control)
331 1
Jebel Ghozlane
348
7943
36999
205
Hammam Zriba
(control) 8 91
493 nd
2235
12674 35
Nd: not detected
The agricultural soils near the old mining sites are rich in EPT, their contents exceed that of the local geochemical background. 5

6. GOLDSCHMIDT 2019 Results Dissolution of carbonates
3- Evaluation of PTE mobility in soil
Dissolution of carbonates
Evolution of conductivity and pH as a function of time
Dissolution of calcite & dolomite
Evolution of the concentration of Mg and Ca as a function of time during extraction with LMWOAs 6

7. Thank you for your attention