Characterization of artisanal gold mining activities in the tropics and their impact on sediment loading and stream flow in the Okame River catchment, Eastern Uganda
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- 作者：Bernard Barasa ; Vincent Kakembo ; Tiller Karl
- 刊名：Environmental Earth Sciences
- 出版年：2016
- 出版时间：July 2016
- 年：2016
- 卷：75
- 期：14
- 全文大小：2,800 KB
- 刊物类别：Earth and Environmental Science
- 刊物主题：None Assigned
- 出版者：Springer Berlin Heidelberg
- ISSN：1866-6299
- 卷排序：75
文摘
Artisanal gold mining activities continue to degrade water resources in the tropical watersheds. In this study, we examined the spatial distribution of artisanal gold mining activities and their impact on sediment and mercury concentration in the Okame River catchment, Eastern Uganda. The spatial distributions of mining activities were assessed using both a TerraSAR-X radar satellite image of 2008 and Landsat image of 2013. Water samples and river bed deposits were collected on a monthly basis for a period of 1 year to assess the impact of mining activities on the streamflow variations and sediment concentration. Our results showed that the distribution of gold mining activities increased from 4.5 km2 in 2008 to 19.9 km2 in 2013. Human-induced sediment loading due to gold stone washing in the sampled tributaries of Okame River was responsible for the high concentration of suspended sediments (CSS), mercury and low water levels than prior to gold stone washing. River Omanyi (0.0191 mg l−1) was the most highly contaminated stream with mercury followed by Nankuke River (0.0163 mg l−1) and Nabewo River (0.0158 mg 1−1) in the Okame. There was also a significant concentration and trend of soluble mercury contamination from the sampled rivers (R2 = 0.8). The average concentration of mercury was found to be 0.004 ± 0.0009 mg l. This paper notes that artisanal mining activities have led to the reduction in streamflow rates, change of streamflow course and colonization of stream banks by riparian vegetation.KeywordsArtisanal gold miningSedimentsTerraSAR-XMercuryStreamflow