Occurrence of arsenic in groundwater, soil and sediments in Tanzania

摘要

Tanzania is among the sub-Sahara African countries where most of the rural populations use ground water for drinking and other household activities. The presence of elevated concentrations of arsenic in some parts of Tanzania is possibly related to both geogenic and anthropogenic sources. From its origin in the bedrock, inorganic As enters into soil where its concentration depends on the parent rock, climate, forms of As, redox conditions of the soils as well as anthropogenic activities. The interactions of water with rocks and sediments together with environmental deposition have resulted into high concentration in groundwater. Microbial activities in soil and sediments may produce the methylated form of As which are volatile in nature and can re-enter the atmosphere and ultimately be re converted back to inorganic forms. Exposure to elevated concentration of arsenic causes arsenicosis. Further investigations are needed in order to come up with a comprehensive report concerning the occurrence and distribution of As in Tanzania.