Group 3
JICA-JST Project
The project for visualization of impact ofchronic/latent chemical hazard and geoecological remediation in Zambia
Toshifumi IGARASHI
Vice dean of Faculty of Engineering

http://www.eng.hokudai.ac.jp/english/

CONTENTS
1. Background and purposesof group 3

5. Dust investigation
6. Probable countermeasures

2. Activities of group 3
3. Preliminary experiments
4. Pilot-scale tests** sheets1Background and purposes of group 3

Hokkaido University2

SceneryBackground and purposes of group 3• Group 1: Investigation of surface conditions by remotesensing methods and evaluation of effectiveness ofvegetation• Group 2: Epidemiological survey of Pb intake• Group 3: Investigation of Pb diffusivity in theenvironments and proposal of candidate remediation
methods• Full-scale remediation in Kabwe by WB and satreps etc.

3

Main activities of Group 3• Preliminary experiments for pilot-scale experiments

Characterization of mine wastes disposed and/or recycled
Application of promising remediation methods (Physical, chemical,biological, and/or electrokinetic methods) in the laboratory• Pilot-Scale is situ experiments in UNZA
Plan and construction of impoundments
Monitoring the diffusivity of Pb contained in the impoundments

Evaluation of the diffusivity of Pb
Proposal of remediation methods• Investigation of hydrogeological condition and dust distributionin kabwe
Investigation of hydrogeological condition in Kabwe
Characterization of Pb in dusts
Spatial distribution of dust
• Proposal of candidate remediation method in Kabwe

4

Major Exposure pathways of Pb

5

Concept of exposure of Pb• Critical pathways of Pb during a rainy season consist of surface runoff andinfiltration into underground.

• Critical pathways of Pb during a dry season is dispersion with dust.
Dust

Dust

Subsidence
Mine wastes
Primary source

Groundwater/ surface watercontamination

Dispersed wastes → Reprecipitation
Secondary source
6Promising countermeasures against cutting the pathways
To reduce the concentration of dust
Covering with uncontaminated soils
Covering with sheet or other materials

To reduce the solubility of Pb
Mixing with chemicals (e.g., adsorbents) for reducing the solubility

To clean up surface soils
Washing contaminated soils

Removing contaminated surface soil

To prevent contaminated groundwater from diffusing out
Constructing low-permeable layer
Constructing permeable reactive barrier
Monitored natural attenuation
7Preliminary experiments
Characterization of mine wastes/ recycable minerals
Distribution of wastes
Leachability and content of Pb

Investigation of hydrogeology in Kabwe
Geology and hydrogeology in Kabwe
Geochemistry in Kabwe

Investigation of hydrogeology in pilot-scale in situ experiments
in UNZA
Geology and hydrogeology in UNZA site
Geochemistry in UNZA site

Application of candidate remediation methods using collectedsoil samples in Kaber in the laboratory
8Drilling Site/Soil Excavation Site・Drilling Plan No.3 (14°45′48.64′′S28.43′8.02′′N)
Drilling Depth: 15 m

・Drilling Plan No.2 (14°45′9.29′′S28°42′58.45′′N)
Drilling Depth: 15 m
・Drilling Plan No.1 (14°46′25.13′′S28°42′7.72′′N)
Drilling Depth: 20 m
・ Site/Soil Ex. Plan No.1A
Sampling of tailings: 20 t

・Drilling plan No.4 (14°46′56.9′′S28°43′6.03′′N)
Drilling Depth: 15 m

1m

Pilot-scale in situ experiments

2m
Case 1 No countermeasures
Only mine wastes

Case 2 Covering soil 1

Case 3 Covering soil 2

Case 4 Immobilization 1

Case 5 Immobilization 2

Case 6 Other method
10Plan view of the experimental site
Groundwater observation well

Monitoring room
Case 2

Case 1

Meteorological observation

Groundwater observation well Case 6

Case 3

10 m

Groundwater observation well

Case 4

Case 511

Meteorological observation in UNZA

1. Direction of wind
2. Velocity of wind
3. Atmospheric pressure
4. Solar radiation
5. Rainfall
6. Temperature
7. Humidity

12

Storage place of Soil in UNZA

Transportation route
Panorama◎Storage place of Samples in UNZA(15°39′7.85′′S28°33′6.77′′N)

Particle size entering lungs> 7 μm mouth, naris
3.3-5 μm trachea
2.0-3.3 μm bronchus

1.1-2.0 μm<1.1 μm alveolus

14Structure of mobile dust sampler

1. Shelter
2. Sampler with 7 filters
3. Flow meter
4. Switch
5. Vacuum pump

15

Pb content (mg/kg)

Dust concentration (mg/m3)

Distribution of Pb content in dust

Particle size (μm)

Residual
Organic/sulfide
Fe/Mn oxide
Carbonate
Ion exchage

Particle size (μm)
16Organizing the research
UNZA

Related ministries
in Zambia

JICA/JSTWB

HU17Scenery18

end19