Method Verification of Total Digestion Technique for the Determination of Nine Heavy Metals in Soil Using Flame, Graphite Furnace and Cold Vapor, Coupled With Atomic Absorption Spectrometer

In this study a method of quantitative analysis for the determination of total heavy metals in soils by atomic absorption spectroscopy (flame, graphite furnace and cold-vapour options) using USEPA method 3052 sample digestion technique was evaluated and applied. Method parameters such as linearity, accuracy, repeatability, limit of detection, limit of quantification and robustness were assessed using laboratory fortified soil for all heavy metals studied. The results showed satisfactory average recoveries for all metals (65% - 107%) and good linearity in terms of regression co-efficient greater than or equal to 0.997. Repeatability was also verified with relative standard deviation values all less than 10%. Thus, the method was deemed satisfactory and effective, and was used for the intended purpose of heavy metal determinations in surface soils of twenty (20) public parks in Greater Accra Region, Ghana. The results from the monitoring study demonstrated the contributions of anthropogenic activities as sources to heavy metal contamination in the study area as a result of industrialization and urbanization. With mercury ranging from 0.001 – 0.094 mg/kg, cadmium (0.12 – 0.50 mg/kg) and even higher concentrations of lead observed (11.28 – 628.31 mg/kg) confirming the use of leaded fuel in the study area. The abundance order of the heavy metals in surface soils for this study was Fe >> Mn > Zn > Cr > Pb > Cu > Ni > Cd > Hg.