1. Mobility and bioaccessibility of inorganic contaminants in soils in the vicinity of copper smelters (Copperbelt, Zambia) Vojtěch ETTLER 1, Martin MIHALJEVIČ 1 Bohdan Kříbek 2, Vladimír MAJER 2, Ondřej ŠEBEK 1 1 Charles University in Prague 2 Czech Geological Survey, Prague Czech Republic prepared for Windhoek 2012

2. Outline of the presentation Background information (Copperbelt) Spatial metal/metalloid distribution Pollutant mobility in soil profiles Pb isotopic tracing Gastric bioaccessibility of metals/metalloids Conclusions and implications Funding: Czech Science Foundation (GAČR 210/12/1413) IGCP Project No. 594 (Assessment of impact of mining…)

3. Cu-Co mining and smelting (Copperbelt province, Zambia) 30 Mt Cu produced since 1930s average ore grade 3 wt.% Cu 0.18 wt.% Co

4. Screening environmental study topsoils/subsurface maximum values Cu 41900 ppm Co 606 ppm Pb 503 ppm Zn 450 ppm As 255 ppm Kříbek et al. (2010) J. Geochem. Explor. 104, 69-86 Co, Cu – smelter emissions Pb, Zn, As - slags related Cr, Ni – bedrock related Nkana smelter

5. Nkana smelter (Kitwe) in operation 1930-2009 Nkana smelter - view from N

6. Copperbelt smelter emissions TEM Cu sulphide Cu sulphate dust fallout – high metals Cu 20170 ppm Co 1542 ppm Cu-bearing phases (TEM, XRD) chalcanthite (CuSO 4 ·5H 2 O) delafossite (CuFeO 2 ) Cu-(Fe) sulphides Vítková, Ettler et al. (unpublished data) Vítková et al. (2011) Appl. Geochem. 26, S263

7. Nkana smelter Nkana old slag dumps 20 Mt of Cu slag crushing to 15 mm reprocessing in Chambishi slag dust generation Vítková, Ettler et al. (2010) Mineral. Mag. 74, 581. Cu-Fe sulphides Co-Fe sulphides intermetallic compounds alloys

8. Research questions Spatial distribution of metals/metalloids in smelter-affected soils? Solid speciation/fractionation of inorganic contaminants? Vertical mobility in highly polluted soil profile? Bioacessibility of metals/metalloids?

9. Spatial distribution of metals 192 topsoils (Nkana, Kitwe) total digests ICP analyses prevailing wind E-SE to W-NW highly polluted soil profile 110-cm-deep Cu

10. Spatial distribution of metals/metalloids CoAs Ettler et al. (2011) Geoderma 164, 73.

11. Vertical distribution of metals/metalloids Soil mineralogy: quartz, clays (kaolinite), hematite ppm 0-5 cm topsoil TOC 7 wt.% Oxisol – Rhodic Haplustox

12. Chemical fractionation (SEP)

13. Tracing the pollution (3-isotope plot)

14. Spatial Pb distribution (bulk/isotopes) 206 Pb/ 207 PbPb Ettler et al. (2011) Geoderma 164, 73.

15. Pb isotopes and SEP fractions residual fraction – background 206 Pb/ 207 Pb signature (~ 1.35) reducible fraction (Fe oxides) – mixture of natural and anthropogenic Pb minute fraction of Pb bound in mobile forms in deeper soil horizons 1 ppm< 50 ppb 80 ppm Pb

16. Bioaccessibility - health implications soil ingestion 200 mg soil per day more critical for children pica behaviour (up to 10 g/day)

17. Polluted topsoils in the Copperbelt max. content (mg/kg): Cu 27410 Co 606 Pb 480 Zn 450 As 255 mining area (n = 52) smelting area (n = 55)

18. Simple Bioaccessibility Extraction Test (SBET) 0.4 M glycine, pH 1.5 (HCl) – gastric fluid simulation Bioaccessibility: As, Pb (81-100%) Co, Cu, Zn (58-83 %) Ettler et al. (2012) J. Geochem. Explor. 113, 68.

19. Ecotoxicological implications calculated for a child (10 kg) daily intake of 100 mg soil ingested TDI tolerable daily limit (µg/day) As6.7710 Co36.514 Cu17101400 Pb34.236 Zn22.55000 Ettler et al. (2012) J. Geochem. Explor. 113, 68.

20. spatial distribution of metallic/metalloid pollution corresponds to fall-out of the dust from the Nkana smelter chimney extreme contamination (Cu > 3.7 wt.%) remains in the uppermost soil horizons (0-5 cm) indication of minute contaminant downward leaching confirmed by Pb isotopic tracing Conclusions and implications

21. Cu, Pb and As are bound in available fractions (exchangeable and reducible) >>> bioavailability (crop contamination) >>> slow downward leaching during the rainy seasons high risk for human health related to soil ingestion

22. Thanks for your attention! Kříbek et al. (2010) J. Geochem. Explor. 104, 69. Vítková, Ettler et al. (2010) Mineral. Mag. 74, 581. Vítková, Ettler et al. (2011) Appl. Geochem. 26, S263. Ettler et al. (2011) Geoderma 164, 73. Ettler et al. (2012) J. Geochem. Explor. 113, 68.