Assessment of uranium levels in waterand soils and its uptake by sorghum and sunflower in Singida Urban District, Tanzania

A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN SOIL SCIENCE AND LAND MANAGEMENT OFSOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA 2016

In Tanzania, uranium deposits have recently been found in Bahi and ManyoniDistricts. Due to suspected high uranium levels in water sources as reported by District water authoritiesin Singida District, this study was carried out to determine levels of uranium in soils, and water and its uptake by commonly grown food cropsfor enhancing public awareness and safety to the residents of Singida Urban District. Rock, soil and plant samples were collected randomly from farmer’s field.Water samples were collected from various water sources in Singida Urban District. Laboratory analyses of soil, rock and plant samples werecarried out at the Geological Survey of Tanzania in Dodoma and Soil Science laboratory at Sokoine University of Agriculture while water samples were analysed atthe Government Chief Chemist Laboratory in Dar es Salaam. Results foundin soil, water, and rocks. The highest U level in soil of 15.4mg kg-1was obtained at Burudani area and the lowest level of<0.01mg kg-1was obtained at Kwa Askofu area. The concentration of uranium in rocks ranged from 20.1 to 31.5 mg kg-1, which in some places washigher than the critical level of 23 mg kg-1 recommended for agricultural land use. Uranium concentrations in sorghum and sunflower grainswere found torange from 1.4 to 5.2 mgkg -1, while in leaves it was less than 2.3 mgkg -1. Uranium concentrations in water ranged from 0.058 to 1.097 mgL-1, the values which were higher than 0.03 mgL-1tolerable limit set by WHO for human and animal consumption. It was concluded that uranium contents found in soils are within the tolerable limit set for agricultural use and consequently sorghumand sunflower grown in the District are safe for human and animal consumption. Most water sources in the District had higher levels of Uranium and thus, should not be used for safety reasonsunless they are treated to reduce uranium concentration. Further studies are recommended to assess uranium concentration in fish, and soda ash,which are produced from lakes and in Singida Urban District.