Heavy Metal Pollution of In-situ and Surrounding Soils Profiles at Municipal Solid Waste Dumpsite

Abstract

Aims: To investigate the levels, variability and degree of heavy metal pollution in in-situ municipal solid waste dumpsite soil (WDS) compared to adjoining area (CS) at 100 – 120m from dumpsite as a contribution to global knowledge of pattern of pollution and data base at dumpsite. Study Design: Field-scale investigation of nine heavy metals (HM) at source pollution site and surrounding soil. Place and Duration of Study: Uyo municipal solid waste dumpsite in 2010. Methodology: Core sampling of soil at solid waste dumpsite and at 100 – 120m away, taken at 0-10cm and 10-20cm profile depths at 4 spatially different points. Acid digestion of HM in soil samples and determination of elemental HM concentration by flame AAS. HM pollution level was assessed using contamination factor, metal pollution index; ANOVA, and covariance for spatial variability. Results: Mean concentrations of nine heavy metals at municipal waste dumpsite soil were significantly (P < .01) higher than the un-dumped surrounding soil, and gave high mean metal pollution index of 5.21 for the overall soil profile. Toxicity was indicated for Fe, Ni, Pb, and B. Correlation between mean HMs at WDS and CS was very low (R = .488) but difference was significant (P = .05), indicating no lateral transfer to fringe area at 100 – 120m away. Conclusion: Heavy metal pollution in municipal solid waste dumpsite soil was higher at all profile depths than in control soil with contamination factors of 3-22 times the control soil values. Pollution was site-specific / anthropogenic (from waste deposition and leachate) rather than terrigenous. Fringe fields at 100-120m from dumpsite, except downslope, were buffered from dumpsite pollution. More research on deeper profile and minimum pollution - free buffer distance are recommended.