ASSESSMENT OF TRACE-METAL EXTRACTION TECHNIQUES WITH REFERENCE TO AQUATIC SEDIMENTS

Different techniques have been employed to determine the extractability of non-residual metals from aquatic sediments. The methods classified as acid extractable, cold extractable and alkaline fusion extractable were compared on the basis of their efficiency in extracting metals responsible for pollution in streams and rivers in the Plateau state of Nigeria. The results show that optimum recovery of any metal depends on the choice of the decomposition procedure. While the cold extractable method showed affinity for most of the metals, copper and tin were optimally recovered by the acid digestion method. Generally, fusion methods gave scant metal recoveries which could be attributed to the low silicate content of the sample and volatilisation losses. In all cases the samples were quantitatively analysed by atomic absorption spectrophotometry and the error due to determination calculated as standard deviation.