The data collected were analyzed for descriptive statistics (meanand standard deviations) using the Statistical Package for SocialSciences (SPSS) for Windows (SPSS 13.0).The metal remediated (%) by ‘compost-only’ and ‘com-post + plant’ in the contaminated soil was calculated using theformula shown in Eq. (1).
% Metal Remediated
= Cm −
Cr
Cm
×
100 (1)where Cmis the concentration of metals in polluted soil and Cristhe concentration of metals in remediated soil.Enrichment Factor (EF) of soil samples was also calculated toassess the impacts of anthropogenic or natural activities in soil.EF value less than 2 indicates low enrichment and less influenceof anthropogenic activities. EF value between 2 and 5 shows amoderate enrichment while EF value greater than 5 is significantlyenriched [27]. EF was calculated as the double ratio of the concen-tration of a measured element to the reference element in soil andthe earth crust [28]. Calculation of EF is expressed in Eq. (2).
EF
= [Ca] / [Xa] Soil
[Cb] / [Xb] Crust
(2)where Caand Xaare the concentrations of desired and referenceelements in the soil samples while Cband Xbare the concentra-tions of desired and reference elements in the earth crust. Referenceelements are usually taken as Al, Li, Sc, Ti, Zr, Mn and Fe [29]. Inthis study, Mn was selected as the reference material being themost abundant element observed in the analyzed soil samples. The[Cb]/[Xb] crust ratio was adopted from Wedepohl [30] composi-tional values for continental earth crust.Bioaccumulation Factor (BF) was determined as an indicationof metal accumulation in plant. BF value greater than 1.0 indi-cates high accumulation of metal. BF was calculated to determinethe amount of metals accumulated by the plant using the formulashown in Eq. (3).
Bioaccumulation Factor
= Cp
Cs
(3)where Cpis the concentration of metals in plant and Csis the con-centration metals in soil.