1 Multivariate analysis of the effects of age, particle size and landfill depth on heavy metals pollution content of closed and active landfill precursors 3 4 A.O. Adelopo 1 , P. I. Haris 3 , B. I. Alo 2 , K. Huddersman 3 , R. O. Jenkins 3 5 1 Department of Works and Physical Planning, University of Lagos, Lagos, Nigeria 6 2 Department of Chemistry, University of Lagos, Lagos, Nigeria. 3 Faculty of Health 7 and Life Sciences, De Montfort University, The Gateway, Leicester LE1 9BH, UK 8 9 Abstract: Multivariate analysis of a heavy metal pollution survey of closed and active landfill 10 precursors was carried out in order to compare environmental risk levels in relation to age, 11 particle size and depth of the precursors. Landfill precursors (77) were collected and analyzed 12 for 15 USEPA toxic heavy metals using ICP-MS. Heavy metals concentrations in closed 13 landfill precursors were significantly higher than those in the active landfill for 11 of 15 heavy 14 metals investigated (closed landfill order: Fe > Al > Mn > Cu > Pb > Ba> Co > Cr > Ni > Cd 15 > As > Se > Ti). Cluster analysis and correlation studies indicated the distribution of the 16 metals was more influenced by landfill precursor size than by depth of the sample. Principal 17 component analysis (PCA) showed that 10 of 15 of heavy metals of both landfill precursors 18 were from similar anthropogenic sources. Heavy metals pollution indices (Igeo > 5, EF > 40 19 and CF > 7) of both active and closed landfill precursors exceeded limits in the order of Zn > 20 Cd > Pb > Cu > Ag, indicating a major potential health risk influenced by age and particle 21 size of precursor. Zn, Cd, Cu and Pb of both landfill precursors exceeded the USEPA set 22 standard for assessment of human health risk for each of the metals (1×10 -4 to 1× 10 -3 ). This 23 study highlights the need for the integration of a clean-up process for precursors from both 24 types of landfill to reduce possible environmental pollution during a reuse process. 25 Keywords: landfill precursor, pollution index, particle size, heavy metals, human health 26 risk, landfill 27