A comparison of two digestion methods and heavy metals determination in sediments

This study was conducted to evaluate the levels of heavy metal concentrations in sediments and also involves a comparison of two different digestion protocols. The first digestion procedure was done with a mixture of hydrochloric acid and nitric acid while the second digestion method was done using the United States Environmental Protection Agency method 3052 which comprises nitric acid, hydrofluoric acid, hydrochloric acid, and hydrogen peroxide. The sediment samples were analyzed for cadmium, copper, iron, lead, zinc, chromium, manganese, nickel (Cd, Cu, Fe, Pb, Zn Cr, Mn, and Ni) with the aid of atomic absorption spectrophotometer. Concentrations of metals ranged 0-7.0 mg/kg for Cr, 0.5-20.0 mg/kg for Cd, 10.8-112.0 mg/kg for Fe, 0.10-7.20 mg/kg for Pb, 45.69-184.96 mg/kg for Cu, 1.0-73.75 mg/kg for Zn, 1.5-19.7 mg/kg for Mn and nd -3.0 mg/kg for Ni. The order of concentrations of the metals in the samples are Cu > Fe > Zn > Cd > Mn > Pb > Cr > Ni. The second digestion method yielded higher levels of metal concentration. Comparison with theWorld Health Organization (W.H.O) standards for marine sediments showed that the average concentrations of heavy metals were within the permissible limits. Close monitoring and more publicity are further needed to discourage further pollution of the area.