INITIAL TRANSMISSION ELECTRON MICROSCOPY (TEM) INVESTIGATION OF FINE PARTICULATE FROM SURFICIAL SEDIMENT IN KABWE, ZAMBIA: NEW CONSTRAINTS ON THE NATURE OF METALS OF ENVIRONMENTAL CONCERN IN A MAJOR LEAD IMPACTED REGION

Kabwe, Zambia is located in the central province of Zambia. It is located about 150 miles outside of the capital and was home to the Broken Hill Mine. The Broken Hill Mine was predominately a lead, zinc and cadmium mine that was in operation from 1902-1994. During this period of operation there were no regulations established to prevent or control human exposure and environmental contamination derived from mine waste. Although there is currently no mining activity, the site is still a major contributor to metal pollution in Kabwe owing to large volumes of abandoned tailings and limited smelting activity. This is a concern because lead, zinc and cadmium have significant negative impacts on the environment and organisms. Surficial sediment and soil samples were acquired to determine the nature of the mineralogical and geochemical composition of fine particulate matter in Kabwe. Surficial soil samples were analyzed by using (TEM). In the analysis, many samples contained PM2.5 that had iron-manganese oxide phases with detectable lead, zinc, chromium and nickel content. These phases varied from crystalline to amorphous, with selected area electron diffraction (SAED) of some particles being consistent with goethite or goethite-like minerals and others having faint rings or functionally no diffraction. Particles less than 300 nanometers in diameters commonly occur. Kaolinite, and to a lesser degree illite comprise the dominant phyllosiclates in the fine fraction and these particles have far less lead and zinc associated with them, however aggregates of these minerals and iron-manganese oxides with lead and zinc occur. Technogenic spherules that would be derived from smelting and other industrial activities are conspicuously absent in samples investigated thus far. Cadmium has not been detected in TEM samples to date. Preliminary TEM results indicate that there is a substantial reservoir of lead and zinc PM2.5 in surficial sediment that could be re-suspended by traffic and wind, thus being a potential source of metal exposure to the population. TEM data provide physical constraints that may be useful understanding details of lead and zinc exposure to the population and potentially provides constraints for interpreting geochemical patterns.