Spatial Distribution of Mercury and Arsenic Levels in Water, Soil and Cassava Plants in a Community with Long History of Gold Mining in Tanzania

摘要

This study examined the spatial distribution of total mercury (THg) and total arsenic (TAs) in water, soil and cassava (Manihot esculenta) (leaves and roots) samples taken from areas in Rwamagasa village in northwestern Tanzania where daily living activities occur in close proximity to extensive artisanal and small scale gold mining. Results indicated that 33.3 % of the water sources had THg levels above the WHO guideline of 1.0 mu g/L for safe drinking water, and 12.5 % had TAs levels above 10 mu g/L. Cassava leaves were found to have higher THg (ranging from 8.3 to 167 mu g/kg) and TAs (ranging from 60 to 1,120 mu g/kg) levels than cassava roots, which ranged between 1.2-8.3 mu g/kg for THg and 25-310 mu g/kg for TAs. Concentrations of THg and TAs in soil samples ranged between 5.8-1,759 and 183-20,298 mu g/kg, respectively. Both THg and TAs were found to be distributed throughout Rwamagasa village.