Assessing the influence of compost and biochar amendments on the mobility and toxicity of metals and arsenic in a naturally contaminated mine soil, Environmental Pollution 186 (2014) 195-202


Amending contaminated soils with organic wastes can influence trace element mobility and toxicity.
Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts
following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a
pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and
Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility
and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved
organic carbon primarily controlled metal mobility after compost amendment. Individually, both
amendments induced considerable solubilisation of arsenic to pore water (>2500 μg/L) related to pH
and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous
reductions in extractable metals and increases in soluble nutrients (P). Thus the measureemonitor-
model approach taken determined that combining the amendments was most effective at
mitigating attendant toxicity risk.

Luke Beesley a,*, Onyeka S. Inneh b, Gareth J. Norton b, Eduardo Moreno-Jimenez c, Tania Pardo d, Rafael Clemente d, Julian J.C. Dawson a
a The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK - b Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU, UK - c Universidad Autónoma de Madrid, 28049 Madrid, Spain - d CEBAS-CSIC, PO Box 164, 30100 Espinardo, Murcia, Spain