|Elliott Hamilton (right) sampling with partners from CBU and ZARI|
In November 2014, barely a month into my part-time PhD, I visited Africa for the first time with Michael Watts and Murray Lark to undertake fieldwork in the Copperbelt region of Zambia.
Chromium exists in the environment as trivalent (Cr(III)) and hexavalent (Cr(VI)) forms. Cr(III) plays a role in the metabolism of carbohydrate, fat and protein. Cr(VI) is released primarily through industrial processes such as wood preservation and leather tanning, it is toxic and a known carcinogen. Cr(VI) is also more mobile in the environment, with common soil parameters such as pH and soil organic carbon (SOC) dictating species distribution and bioavailability.
|The Black Mountain, Kitwe|
These studies focused predominantly on the metals mined, such as copper, cobalt and zinc, with little attention devoted to chromium and its species. The vicinity of Kitwe was chosen for a preliminary sampling campaign undertaken in November 2014 to establish chromium concentrations at a number of sites in close proximity to mine tailings, with a view to carrying out crop trials and species kinetics experiments in parallel with experiments undertaken during a recently funded RS-DFID project (see Michael Watts blog "Geochemisty brings societal benefits ...").
The fieldwork was carried out with partners from the Zambian Agricultural Research Institute (ZARI), Copperbelt University (CBU) and the University of Zambia (UNZA). Four locations were sampled, within half a mile of a tailings heap or smelter. To understand variation at different spatial scales, a nested sampling design was implemented (discussed in more detail in Murray’s blog “Random variables and field sampling”). The laboratory analysis of the soils is now complete; once the data have been interpreted in the context of the sample design I’ll have a better understanding of the spatial variation to plan future sampling and experimental plots with greater efficiency.
|A smelter in Kalulushi|
Ettler, V., M. Vítková, et al. (2014). "Dust from Zambian smelters: mineralogy and contaminant bioaccessibility." Environmental Geochemistry and Health 36(5): 919-933.
Ikenaka, Y., S. Nakayama, et al. (2010). "Heavy metal contamination of soil and sediment in Zambia." African Journal of Environmental Science and Technology 4(11).
Ndilila, W., A. C. Callan, et al. (2014). "Environmental and toenail metals concentrations in copper mining and non mining communities in Zambia." International Journal of Hygiene and Environmental Health 217(1): 62-69.