ENVIRONMENTAL EFFECTS OF ARTISANAL GOLD MINING AT ABANDONED ROSTERMAN MINE AND ITS SURROUNDING, KAKAMEGA COUNTY, KENYA

Abstract

Rosterman mine is an abandoned gold mine located in Kakamega County, of Western Kenya. The mine was started in 1935 and was abandoned without rehabilitation in 1952 with deep open excavations and huge amount of tailings due to non enforcement of rehabilitation policy during the time. Locals have been panning the tailings for gold remains, unaware of the impacts of the leached elements. Water form the nearby stream is used for domestic purposes. Water that has ponded in the abandoned mine pits has been dangerous to both people and animals that drown in it. To enable future rehabilitation there was need to establish the quality of the mine water. The study aimed at assessing the concentration of the leached elements in the abandoned mine water and their influence on the soil pH, salinity and runoff to nearby streams. Samples of mine and the stream water were analysed for various selected total elements (Iron (Fe), Manganese (Mg), Zinc (Zn), Copper (Cu), Lead (Pb), Cadmium (Cd), and Chromium (Cr)) concentrations during the period of October, 2006 to March, 2007. Topographical map Sheets of the area at scale 1:50,000 were used as a base map to plot the sampling sites. The locations sites were geo referenced using a global positioning system (GPS) in Universal Transverse Mercator. Photographs of the sampled areas were also taken. The results showed that the average concentrations of the selected trace elements in stream water were generally higher that in the mine water. However, concentrations Pb, and Cd in both waters were found to exceed the recommended WHO limits of 0.005 ppm, for drinking water and the applies to Fe, which exceeded the 0.3 ppm limit recommended. The results also indicated that the waters’ pH lies between 6.48 and 7.48 which were within the neutral range under neutral range. Partial correlation revealed low correlation between heavy metals and sulphates under the field pH conditions. At 95% confidence level, there was found no variation between levels of heavy metals in the mine waters and the streams suggesting possible other sources of heavy metals into the steams. Recommendations for further studies on the sources of heavy metals to the streams waters were made.