Remediation of a historically Pb contaminated soil using a model natural Mn oxide waste

[Display omitted] •The use of a natural Mn oxide (NMO) waste for the remediation of Pb contaminated soils is reported.•The NMO shows one of the highest Pb sorption capacities reported to date.•Available Pb in contaminated soil effectively binds to the NMO.•NMO addition does not perturb soil microbial communities or their function. A natural Mn oxide (NMO) waste was assessed as an in situ remediation amendment for Pb contaminated sites. The viability of this was investigated using a 10month lysimeter trial, wherein a historically Pb contaminated soil was amended with a 10% by weight model NMO. The model NMO was found to have a large Pb adsorption capacity (qmax 346±14mgg−1). However, due to the heterogeneous nature of the Pb contamination in the soils (3650.54–9299.79mgkg−1), no treatment related difference in Pb via geochemistry could be detected. To overcome difficulties in traditional geochemical techniques due to pollutant heterogeneity we present a new method for unequivocally proving metal sorption to in situ remediation amendments. The method combines two spectroscopic techniques; namely electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). Using this we showed Pb immobilisation on NMO, which were Pb free prior to their addition to the soils. Amendment of the soil with exogenous Mn oxide had no effect on microbial functioning, nor did it perturb the composition of the dominant phyla. We conclude that NMOs show excellent potential as remediation amendments.