The Global Symposium on Soil Pollution #GSOP18 | 2 - 4 May 2018 | FAO Hq Mr. Taher Ajmi, ACTA, Direction des Sols, Tunisia

1. Research - Development Program
METALLIC CONTAMINATION ISSUE OF MINING WASTE
Assessment of heavy metal pollution in the
cultivated area around mining
Medjerda Tunisian Watershed Case Study
Mine Lakhouat ; FEJ Hdoum , Khanguet Kef tout- Tunisie
ATTIA.R, HAMROUNI.H, AJMI.T, HACHICHA.M
International Symposium on Soil Pollution
Sousse 24 to 27 November 2014

2. FRAMEWORK
 This work was the subject of partnership between DG / ACTA, D / SOIL
with several research institutions: FACULTY OF SCIENCES OF TUNIS -
INRGREF – CERTE
 This is a comparative study of morphology and texture impacts on the
Metal Trace Elements distribution and mobility between three sites El
Khouat, Fej el Hdoum, Khanguet Kef Ettout on Medjerda watershed

3. INTRODUCTION
Mining is a very important economic activity, but it generates many
polluants in the environment. Heavy metals are part of these polluants,
Northern Tunisia is an important metallogenic province, producing about 55
million tonnes (Mt) of iron, 2.3 Mt of lead, 2.0 Mt of zinc and 0.8 Mt of
fluorite.
In the northern region of Tunisia, 23 mining sites have been mined and are
now abandoned.
The speed of this pollution depends on several factors including the slope,
the geomorphology of the sites, the properties of the soil but especially the
quantity and the intensity of the rains.

4. PROBLEMATIC
The agriculture lands around the old mines with their high level of heavy
metals are occupied by various vegetation and crops.
The impacts of mine discharges on the sites and surrounding populations
are often disastrous: water quality problems, soil contamination, air
pollution and loss of biodiversity and vegetation cover,
Legislative: Absence of regulation and tunisian standard values.
Institutions: Lack of a clear responsible structure definition (Ministry of
Agriculture / Mines / Industry / Environment),
No clear strategy for the rehabilitation of residues.

5. OBJECTIVES
 Characterization and assessment of the pollution status of agricultural soils,
water and plants around abandoned mines of the Medjerda Watershed (surface
and depth)
 The content and natural dynamics of Metal Trace Elements in crops grown in
these agricultural soils
 Spatialization and mapping of contamination degree
 Assessment of heavy metals mobility and soil pollution risk on the downstream of
mines (diffuse pollution)
 Identifying the major processes and phenomena that influencing the contribution
of these trace elements
 Establishment of a tunisian standard for agricultural soils polluted by heavy
metals
 Support decision-makers in developing effective waste management strategies

6. This study is based on identification and assessment of nature and spatial distribution
of the heavy metal on the soil (surface and depth ) around abandoned mining and
their dynamic in low compartments of the landscape by runoff and wind movement.
It concerns different parts of Medjerdah Watershed (10 pilot areas were selected,
3areas were tested)
JUSTIFICATION WHY MEDJERDA
Fedj El Adoum
El Akhouat
Sidi Bou Aouane
Khanguet Kef Tout
El Grefa
Mateur
Djebba
Ghardimaou
Fedj Assene
Ressas Touiret
 Main watershed
 Dominance of mines on both
sides of the great watershed
 10 deposits sites are spotted
on the watershed

7.  Bibliography and archive consultation: Office of Mines; Dep. Geology - FST,
Other Institutions.
 Characterization and assessment of pollution state.
 30 samples/site divided between discharge, soil, plant and water.
 The strategy of sampling was defined by taking into account the position of
the mine site and the topography of the study area which influences the
dispersion of metals.
 Physical, chemical and mineralogical analyzes are conducted on the
different samples (solid, liquid and plants).
 The mapping of the spatial extent of pollution by toxic metal
METHODOLOGY

8. PRELIMINARY RESULTS

9. Mining district of Lakhouat
Mining district of Fej
Lahdoum
Mining district of Kanget Kef
Ettout
3 sites
STUDY OF MOBILITY OF HEAVY METALS
FROM MINING WASTE (PB-ZN-CD) ,
IMPACT ON SOIL,WATER,PLANTS
QUALITY

10. MINING DISTRICT OF LAKHOUAT
 located in north-western
Tunisia
 This deposit discovered in
1892 essentially treated the
lead and zinc mineral,
 It is a semi-humid bioclimatic
region
 The Lakhouat soils are brown
isohumic
 It is mainly cultivated area;

11.  The mineralogical characterization of
mining discharges shows the presence of:
- Lead sulphides (PbS: Galene),
- Zinc sulphides (ZnS: Sphalerite),
- Iron bisulfides (FeS2: Pyrite and Marcasite)
 The discharges are in the form of three
trapezoidal dikes, H = 10 m; Light gray
color; Without vegetation;
 Subject to water erosion during rainy
seasons.
 The geochemical characterization of
mining discharges shows high levels of
Metal Trace Elements
- Lead (1536 ppm-4184 ppm)
- Zinc (3912 ppm-10070 ppm)
- Cadmium (19 ppm-46 ppm)
0
2000
4000
6000
8000
10000
12000
D1 D2 D3 D4 D5
Teneurs(ppm)
Référence
Zn
Cd
Pb
GRANULOMETRY PH % CACO3
Sandy loam 7,98 – 8,35 36 % - 72 %

12. RESULTS AND INTERPRETATIONS
Sampling was done on 5 transects on agricultural soils
T1
T2
T3
T4
T5

13. SPATIAL DISTRIBUTION OF TOXIC METAL ON LAKHOUAT SOILS
0
500
1000
1500
2000
2500
S1 1 S1 2 S1 3 S1 4
Teneurs(ppm)
Référence
Zn
Pb
0
2
4
6
8
10
S1 1 S1 2 S1 3 S1 4
Teneurs(ppm)
Référence
Cd
The levels of heavy metals: - zinc (2206 ppm -2388 ppm) -pb (1510 ppm- 1820 ppm)- Cd (3-10 ppm)
This soil enrichment can be explained by the proximity to mine wastes following by runoff or wind during dry periods.
Relatively flat topography of the area promotes retention of metallic trace elements.
The first transect T1
0
2000
4000
6000
8000
10000
S1 5 S1 6 S1 7 S1 8
Teneurs(ppm)
Référence
Zn
Pb
0
1000
2000
3000
4000
5000
6000
7000
S1 9 S1 10 S1 11 S1 12
Teneurs(ppm)
Référence
Zn
Pb
The second transect T2 The third transect T3
The lead and zinc content shows a significant decrease while moving away from the source of pollution

14. The decrease of lead and zinc levels, explained by
two agents:
 Distance from the source of pollution
 Management by stabilizing: The benches playing
a crucial role in limiting the mobility of metallic
elements.
The fourth transect T4 The fifth transect T5
0
1000
2000
3000
S2 1 S2 2 S2 3 S2 4
Teneurs(ppm)
Référence
Zn
Pb
0
1000
2000
3000
4000
5000
S2 5 S26 S2 7 S2 4
Teneurs(ppm)
Référence
Zn
Pb
T4
T5
SPATIAL DISTRIBUTION OF TOXIC METAL ON LAKHOUAT SOILS

15. SOILS PROFILE
Profil I Profil II Profil III
THREE PROFILS WERE SAMPLED
METHODOLOGY

16. Profil I ( +rich, close to the dike ) Profil II Profil III
VerticaldistributionofPb,ZnandCdinsoilprofiles
Decrease in levels of Pb, Zn and Cd in a function of depth.

17. The major elements:
High levels of Mg++ (0,29 % - 0,83 %) presence of magnesian carbonates
High levels of Ca++ ( 0,17 % - 0,42 %) abundance of calcium carbonates
This abundance reduces the absorption of heavy metals
 Low levels of Na+ et K+.
The surroundings of the Lakhouat mine site are strongly affected
by the old mining activity
RESULTS AND INTERPRETATIONS
Zn (ppm) Pb (ppm) Cd (ppm)
Akhouat Soil 9780 2394 43
Sample (control) 42 0,45 37
Council of the European
communities (CEC),1986
300 300 3
OMS 90 35 0,35
Texture PH (H2O) Carbonates (%) Organic matter (%)
Silty-clay-sandy 7,80 - 8,97 35 % - 60 % 2,93 %- 6,43 %

18. Profils de sol Matériel végétal Pb (ppm) Zn (ppm) Cd (ppm)
P1
Hirshfilotier
geurculates
Roots 164,2 1529 0,6
Aerial part 151,4 757 1,9
P2 Atractylis sp
Roots 199,4 1184 2,2
Aerial part 33,5 277 2,1
Oenouhle
globuloser
Roots 121,4 821 2,5
Aerial part 51,95 290 0,95
P3 Blés
Roots 77,95 350 1,05
Aerial part 29,55 71 0,85
Teneur moyenne dans les plantes Cottenie (1983) 5 100 0,01
PLANTS
Significant accumulation in the roots than in the aerial part
RESULTS AND INTERPRETATIONS

19. The assessment of the impact of tailings from the old mine of Lakhouat on
farmland shows that :
 The sandy loam texture of tailings and the lack of vegetative cover in the
discharge causes erosion dikes and transport its sediment by wind and water
to the downstream region
 The soils have a high levels of Pb, Cd and Zn with a significant enrichment
on the surface layers close to the pollution source which decreases in
accordance with the depth and away from the dikes.
 the dispersion of toxic elements is limited due to the carbonate nature but
considerable power of wind and water action remains active.
 Storage of tailings dams form without prior care is a serious threat to the
environment. We must find solutions to best limit the dispersion of emissions.

20. Fedj El Adoum mining
Accented topography
Presence of a large ravine

21.  The soils of Fedj El Adoum are mainly
agricultural land.
 Crude mineral soils, Low alluvial soils,
Fersiallitic clay soils, Calcimagnetic soils
 Semi-arid bioclimatic stage with
temperate winter.
 An annual rainfall is about 400-460 mm
 The mining discharges are stored in the
form of three dikes (Height= 15m), Gray
color without vegetation
 Subject to water erosion during rainy
seasons
21

22. STUDY AREA: SAMPLING PATH
22

23. % CaCO3 pH EC (ms/cm)
7% -30% 6,55-7,4 2,6-10,62
0,00
500,00
1000,00
1500,00
2000,00
2500,00
D1 EcD1 EnD1 FnD1 EsD1 FsD1 EeD1 FeD1 EoD1 Fo D2 Ec D2 En D2 Fn D2 Es D2 Fs D2 Ee D2 Fe D2 Eo D2 Fo
Teneurs(ppm)
Référence
Cd (ppm)
Pb (ppm)
Zn (ppm)
RESULTS AND INTERPRETATIONS
Granulometry
sandy loam
23

24. pH Cd (ms/cm) Organic matter (%)
8,1-8,72 0,55-4,01 0,56-8,47
0
20
40
60
80
100
120
140
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16
Teneur(ppm)
Référence
Cd
Pb
Zn
Granulometry
Silty clay
RESULTS AND INTERPRETATIONS
24

25.  the contents of the trace element in the lake are low, more sampling and
investigation are needed to confirm this result
RESULTS AND INTERPRETATIONS
25

26.  The results of analysis of mining discharges show values of 1832 ppm for Pb
2180 ppm for Zn, 49ppm for cd
 The Lakhouat mine tailings are more contaminated than those of Fedj El
Adoum
 At the soil level there are relatively low concentrations of metallic trace
elements
 The topography of the area is very accentuated, a very deep ravine, wadi
crosses the landscape and drains the most important quantities of the MTE
 The waters of the lake are not contaminated
FOR THE CASE OF THE ABANDONED
MINE OF FEDJ EL ADOUM

27.  The study area belongs to the region of Nefza (Bèja) with a humid climate
 This is a very different particular context compared to the other two cases from the
morphological point of view (Dikes are flat)

28.  Mining discharges of Khanguet
Kef Ettout has a light gray color
and covered by dense vegetation
of trees, shrubs and herbaceous
plants scattered.
 This area is characterized by
vertisols, calcimorphic and a Red
Mediterranean soils.
 These soils are essentially
farmland with a very sensitive to
erosion

29. SAMPLING POINTS ON
AGRICULTURAL LAND
AND IN THE RIVER

31. 0
1000
2000
3000
4000
5000
6000
7000
8000
D1 D2 D3 D4 D5 D6
Teneursenppm
Echantillons
Cd (ppm)
Pb (ppm)
Zn (ppm)
• Plomb (1340,5 - 7384 ppm)
• Zinc (613,5 - 3185 ppm)
• Cadmium (18,2 - 43,6 ppm)
Granulometry pH
Calcaire
total
Calcaire
actif
Organic
matter
A sandy-loam facies 7-8,5 59- 82% 11-28% 0,69- 1,75%
The values shows that the maximum
of pollution focused on tailings ,high
levels exceeding CEE standards of soil
quality

32. 0
50
100
150
200
250
300
350
400
450
St
S1
S2
S3
S4
S5
S5
S7
S8
S9
S10
S11
S12
S13
Teneursenppm
Echantillons
Cd (ppm)
Pb (ppm)
Zn (ppm)
• Plomb (15,4 - 308 ppm)
• Zinc (4,6 - 432,7 ppm)
• Cadmium (0,1 - 4,6 ppm)
Metal Trace Elements values
in soils are relatively low

33. The concentration of organic matter in soils can be
responsible for the accumulation of heavy metals.
The abundance of carbonates (calcite) thus reducing the
mobility of MTE and generating an alkaline pH on the soil.
pH Calcaire total Organic Matter
7,1-8,5 3%- 38% 1,67- 3,1
 Lead sulphides (Galena : PbS )
 Iron sulphides (Pyrite : FeS2)
Granulometry Lime-clay soils and loamy soils

34.  It was important to characterize the metal content of the tailings and to
assess how far the district could contaminate soils, water and plants.
 The speed of this pollution depends on several factors: the slope, the
soils properties, the position of the mine, the intensity of rains and wind
direction.
 This results can lead:
-to establish a contamination tendency in Medjerdah watershed,
-to classify and compare pollution process and factors in different sites,
-to determine tunisian standard regulations for heavy metals in
cultivated lands,
-to propose control measure pollution,
-to develop advanced technology for management of mining and
industrial discharges.
CONCLUSION

35. THANK YOU FOR
YOUR ATTENTION