Determination of heavy metals concentration in water, sediments, plant and fish in Nyumba ya Mungu dam, Tanzania

This study determined the heavy metals (Pb, Zn, Fe and Cu) concentration by atomic absorption spectrometry in water, sediments, plant and fishes from nine stations of Nyumba ya Mungu Dam in Kilimanjaro region. The dam serves a number of ecological functions, ranging from habitat to aquatic animals also supporting human life, wildlife, and plant growth. The concentration of copper ranged from 6.57 mg/kg to 126.21 mg/kg, iron ranged from 4796.11 mg/kg to 12012.46 mg/kg, lead ranges are 98.15 mg/kg to 142.67 mg/kg and zinc ranged from 77.65 mg/kg to 184.32 mg/kg. The content of heavy metals in plants were 1.07-142 mg/kg – CU, 2031.4498 – 555003.06 mg/kg-Fe, 39.71 -146.00 mg/kg-Pb and 73.58-169.00 mg/kg- Zn. The total concentration of heavy metals in water samples ranges from undetectable amount to 1.1 mg/ l for copper (Cu), 28.30 to 69.89 mg/l for iron (Fe) 0.5-4.0 mg/l for lead (Pb) and 0.2 to 0.8mg/l for zinc (Zn). The concentration of heavy metals in sediments ranged from 11.69-57.55 mg/kg for copper (Cu), 7119.83-91502.53 mg/kg for iron (Fe), 14.90-234.10 mg/kg for lead (Pb) and 168.77-320.77 mg/kg for zinc (Zn). The elevated level of heavy metals in Nyumba ya Mungu Dam may be attributed to natural factors, industries from Arusha and some parts of Kilimanjaro Region which directly and indirectly discharge their untreated wastes to the streams and rivers then later into Nyumba ya Mungu. There is a need for constant monitoring of heavy metals in Nyumba ya Mungu and planting more plants with high uptake of heavy metal also to refrain products with heavy metals, in order to ensure the environmental sustainability of the dam, as heavy metals are non biodegradable.