Levels of Heavy metals in Soil, Water, and Plants and Variation of water Quality Parameters at Vikuge in Kibaha District, Tanzania

The levels of toxic heavy metals ( cadmium, lead, copper, zinc, chromium and iron) were checked in soil, water, plant leaves, fruits and roots obtained at Vikuge in Kibaha, Tanzania. The samples of water from the three wells were taken in triplicate, similar to the samples of plants, fruits and roots. The samples were analyzedusing standard methods. Majority of samples had higher levels of heavy metals than the acceptable by WHO and Tanzanian limits. High levels were detected in vegetables compared to fruits and water samples. In sweet potato leaves lead levels ranged from 0.85 mg/kg to 0.98 mg/kg which is over 1500 times greater than the WHO acceptable limits (0.02 mg/kg). Highest alarming levels for Pb in all samples ranged from 0.790 mg/kg to 1.450 mg/glare much associated with the contamination of water around used to irrigate the plants. Water samples had high levels of Pb ranging from 1.146 mg/kg – 1.190 mg/kg which were about 12 times higher than WHO acceptable limits and 40times higher than the Tanzania acceptable limits (0.100 mg/kg). The highest levels of iron in all samples determined are not surprising as this may be from the contamination of soil and water due to natural and anthropogenic sources. The average of metal concentrations in vegetables i.e cassava leaves, which is commonly used in Tanzania and Vikuge were Pb1.101 mg/kg, Cu 0.306 mg/kg, Zn 5.640 mg/kg, Cr 0.262 mg/kg and Fe 2.568 mg/kg, then if consumed as recommended the contribution of heavy metal intake for an average human being from the vegetable diet is approximately 440.4 mg Pb, 122.4 mg Cu, 2.256mg Zn, 104.8mg Cr and 1,027.2mg/kg Fe. The mean daily intake recommended value of these elements are 2.4 mg Cu, 8.4 mg Zn and 18.0 mg Fe. Regarding the Water Quality Parameters, the results indicated all iterms have their values below WHO/FAO limits thus brings no health hazards