Research on Concentration and Chemical Speciation of Heavy Met-Als in Urban Soils of Warri, Nigeria
To determine whether substantial concentrations of the metals are mobile and bioavailable in Warri’s urban soils, a chemical method (1) and Tessier’s method  were used to determine the pseudo total and chemical speciation of manganese, chromium, lead, and zinc. The intervention values were determined to determine whether the metal contamination had reached the point that the soils needed to be handled. Using a stainless steel augur, ten soil samples were collected from five sites (Esisi, Apala, Airport Road, Ugborikoko, and NPA Expressway Refuse dumps) (5 top soils 0 -15 cm and 5 bottom soils 15 – 30 cm). The Atomic Absorption spectrophotometer technique was used to analyse the sample solutions. The average total heavy metal concentrations in top soils were found to be 4. 00 0.00 to 111.00 7. 00 ppm Mn, 9. 13 0.13 to 292. 28 7.82 ppm Cr, 0.08 to 493.00 3.00ppm Pb, and 35.00 0.00 to 1012.00+ 2.00ppm Zn. 7.00 0,00 to 160.00 0.00 ppm Mn, 35.05 0.40 to 263.00 0.00 ppm Cr, 0.08 to 286.00 6.00 ppm Pb, and 64.00 4.00 to 1458.00 8.00 ppm Zn have been found in bottom soil samples. The abundance ratios mentioned were in the order Zn >Cr > Mn > Pb. In certain soil samples, the values recorded in this analysis are higher than those reported by the Federal Environmental Protection Agency (3). 190.40mg/kg Cr were collected as intervention values. Pb concentrations of 312.10 mg/kg and Zn concentrations of 257.67 mg/kg. In all of the soil samples, total Zn is higher than intervention values, total Cr is similar to intervention values, and Pb is lower than intervention values. Chemical properties such as pH, total organic carbon, and carbon equivalent content (CEC) were also examined. Six soil samples (3 top soils and 3 bottom soils) were chosen from three dump sites (Esisi, Apala, and NPA Expressway) and chemical partitioning was determined using Tessier’s method. Except for Pb, the metals showed the highest concentration in the Fe-Mn oxide fraction. The exchangeable process is not correlated with Pb. Except for Pb, all of the metals had large concentrations in the non-residual fraction. This demonstrates that large amounts of metals are mobile and bioavailable to plants and other ecological materials. The bioavailable values found in this analysis are higher than those found in soils that are not polluted. [two] The quality of Cr, Zn, and Mn in soils is also related to the pH of the soil. The distribution of a single chemical element among different species or groups is known as chemical speciation. Trace metals can be found in a variety of soil components and are associated with them in a variety of ways.
Author (s) Details
Chemistry Department, College of Education, Warri, Nigeria.
F. E. Okieimen
Chemistry Department, University of Benin, Benin – City, Nigeria.
E. G. Uwumarongie
Edo State Environmental Consultancy, Benin – City, Nigeria.
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