Cadmium, lead, arsenic and mercury levels in earthenware clay deposits atvume, in the South Tongu district of Ghana, using atomic absorption spectrophotometric technique

This paper screened for potentially harmful heavy metals such as As, Pb, Cd and Hg in earthenware clay deposits at Vume in the Volta region of Ghana using Atomic Absorption Spectrophotometric (AAS) technique. The concentrations of As in the clay samples ranged from 0.90µg/g to 2.04 µg/g with a mean of 1.49 µg/g, and standard deviation of 0.47. Lead levels ranged from 2.85 µg/g to 4.08 µg/g with a mean of 3.67µg/g, and a standard deviation of 0.38. Cadmium was below the detection limit of 0.002 µg/g in some samples: however, the levels measured ranged from 0.15 µg/g to 0.51 µg/g with a mean of 0.29 µg/g, and a standard deviation of 0.13. The concentrations of mercury ranged from 0.18 µg/g to 0.69 µg/g with a mean of 0.53 µg/g, and a standard deviation of 0.15. The levels of Hg,Cd and Pb fell below their respective US EPA(1990) safe levels of 18.0 µg/g, 1.7 µg/g and 80.0 µg/g, except that of As which was above its US EPA(1990) safe level of 0.07 µg/g.The levels of Arsenic in the study area, though higher than the US EPA safe level, were comparable to the worldwide background level of 5 µg/g in soil. The precision and the accuracy of the AAS method were assessed via the use of reference material IAEA Soil-7. The values obtained for the various elements in the standard reference material (by analysing it with the AAS method) compared favourably well with the recommended values as Spearman’s correlation coefficient was + 0.96. The experimental values were within ±5% of the recommended value. The measurement precision determined by the relative standard deviation was within ±4%. With the exception of As levels which need some remediation, the quality of the clay at Vume was found to be generally good for the production of earthenware products.