Cadmium and lead concentration in rice grain, water and soil from the Anum valley irrigation project at Nobewam
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Date
2009-08-09
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Abstract
The Anum Valley Rice Project which is one of the 22 active rice irrigation projects in Ghana. The Oweri and Anum rivers are the two main sources of water for this project. However, wastewater from the Mechanic shops, “Galamsey” sites and Ghana Water Company Limited are discharged into both the Oweri and Anum rivers, which are in turned used to irrigate the rice. The main objective of the study was to determine the levels of cadmium and lead concentrations in the rice grains, irrigation water and soil samples. Also, the irrigation water quality parameters like the electrical conductivity, temperature and pH were determined. The levels of these heavy metals (Cd and Pb) and irrigation water quality were compared with those of WHO/FAO recommended values. At the end of the water quality analysis the electrical conductivity (EC) values of the irrigation water ranged from 17.34 to113.6 dS/m as against the WHO/FAO recommended value of 3.0 dS/m. The pH values of the water ranged between 1.1 and 1.7 as against the WHO/FAO recommended value range of 6.5-8.4. Again, all the values were outside FAO/WHO recommended limit. Cadmium values in the water samples ranged from <0.002 to 0.063 mg/l as against the WHO/FAO recommended value of 0.01 mg/l. All the samples exceeded the FAO/WHO recommended limit with the exception of only three samples which were within the limit. Lead values in the water samples were from <0.01 to 0.372 mg/l as against the WHO/FAO recommended value of 5 mg/l. All the samples were within the FAO/WHO recommended limit.
At the end of the rice grain samples analysis, cadmium levels in the rice grain recorded ranged between <0.002 mg/kg and 0.80 mg/kg as against the WHO/FAO recommended value of 0.5 mg/kg. All the rice grain samples were within the recommended value with the exception of two samples whose values exceeded the WHO value. Lead values in the rice grain ranged between <0.01 and 5.25 mg/kg as against the WHO/FAO recommended value of 3 mg/kg. All the rice grain samples were within the recommended value with the exception of three samples whose values exceeded the WHO/FAO limit.
Cadmium values in the soil samples were between 0.03 mg/kg and 0.47 mg/kg as against the WHO/FAO recommended value of 3 mg/kg. All the samples were within the FAO/WHO recommended limit. Lead values were between <0.01 and 1.74 mg/kg as against the WHO/FAO recommended value of 300 mg/kg. Also, all the samples were within the FAO/WHO recommended limit. The transfer factor values for both heavy metals in the rice grain were high giving a cause for concern for consumers.
Description
A Thesis submitted to the Department of Agricultural Engineering, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the degree of Master Of Science In Soil And Water Engineering.