Lead Contamination: Environmental Geochemistry of Gold Mining Villages in Northwest Nigeria

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Mejia, Lucy Taylor
Geochemical analysis; Pb contamination in NW Nigeria; Cerussite; Galena; ICP-AES; XRD; XRD cluster analysis; SEM-EDS; Multivariate statistical analysis; GIS empirical bayesian kriging analysis; Carbonate combustion analysis
thesis / dissertation description
In summer of 2012, dust and processed ore were collected from ~54 villages by U.S. CDC and Nigerian colleagues after the discovery of widespread lead poisoning in northwest Nigeria, and provided to the Environmental Research Laboratory at GSU. Various geochemical analyses were conducted to assess the magnitude of Pb exposure. ICP-AES determined Pb concentrations as high as 61,000 ppm. SEM-EDS and XRD analyses of high concentration samples (>400 ppm) revealed the presence of gold, galena, and cerussite. XRD Cluster Analysis revealed one outlier and 3 clusters. Samples with Pb>400ppm Pb had a strong correlation between Pb and S. GIS Kriging maps illustrate geochemical spatial distribution. Carbonate combustion analysis found TIC has a negative correlation to Pb. Approximately 3% of samples contained >400ppm of Pb (U.S. EPA RSSL). Discovery of galena (PbS) and it’s secondary weathering product cerussite (PbCO3), a highly bioavailable Pb-bearing phase, were discovered in these high Pb samples, indicating a continuing threat to human health.