Correlation between humic-like substances and heavy metals in composts

Abstract

The purpose of this work was to correlate the humic-like substances content with the content of six heavy metals (Zn, Pb, Ni, Cu, Cr and Cd) in some composts commercialised in Portugal. Four commercial composts, two from non-separated municipal solid waste (MC1, MC2), one from source-separated municipal solid waste (MC3) and one produced from poultry litter (PC), were analysed. The maturity of composts was characterised using the generally accepted humification indices. The MC3 compost showed the lowest heavy metal content. Zn was the heavy metal present in the highest concentration (861 mg/kg dry matter), while Cd showed to be the least representative (3.0 mg/kg dry matter). A correlation analysis indicated that the maturation characteristics of the composts, such as the humic-like substances content, play a significantly role in the bioavailability of heavy metals. Â(c) 2013 Zhejiang University Press and Springer Science+Business Media Dordrecht. All rights are reserved.