Nanoscale zero-valent iron mitigates arsenic mobilization and accumulation in Sinapis alba grown on a metal(loid)-polluted soil treated with a dunite mining waste-compost amendment

Background and aimThe use of amendments to immobilize metals in polluted soils is a widely accepted remediation approach, and in the framework of the circular economy, amendments produced from mining and/or biomass waste have gained relevance. However, the application of such amendments can also mobilize metalloids. Here we propose the combination of nanoscale zero-valent iron nanoparticles (nZVI) with dunite (mining waste) and compost for the remediation and restoration of soil affected by high concentrations of As and metals.MethodsTo this end, we treated pots containing the polluted soil with combinations of dunite, compost, and nZVI for 75 days. In addition, Sinapis alba was used to evaluate the effects of the amendments on pollutant accumulation in the plant. The mobility of the pollutants was monitored through TCLP extraction and by sampling pore water. Furthermore, pH, available P, and cation exchange capacity (CEC) were also determined.ResultsDunite application led to the immobilization of metals, and supplied Mg, thus improving CEC. On the other hand, compost increased nutrient content, and also promoted plant growth. However, this amendment caused a dramatic increase in As accumulation in the plants. Finally, the application of nZVI in combination with the other two amendments was found to be the most appropriate strategy since it not only prevented As mobilization and accumulation but also added nutrients to the soil, thus promoting plant growth.ConclusionThe combination of nZVI with dunite mining waste and compost proved effective for the remediation of soil simultaneously polluted by As and metals.