Comparison of the effectiveness of biochar vs. magnesite amendments to immobilize metals and restore a polluted soil

• Published in: Environmental geochemistry and health Vol. 43; no. 12; pp. 5053 - 5064
• Main Authors: Baragaño, Diego, R. Gallego, José Luis, Forján, Rubén
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-12-2021; Springer Nature B.V
• Subjects: Availability; Brassica; Cadmium; Cation exchange; Cation exchanging; Cations; Charcoal; Composts; Copper; Earth and Environmental Science; Environment; Environmental Chemistry; Environmental Health; Exchange capacity; Geochemistry; Heavy metals; Magnesite; Magnesium carbonate; Metals; Organic soils; Original Paper; Plant growth; Pots; Public Health; Revegetation; Soil amendment; Soil chemistry; Soil contamination; Soil improvement; Soil pH; Soil pollution; Soil properties; Soil remediation; Soil Science & Conservation; Soil stabilization; Soils; Spoil; Stabilizing; Terrestrial Pollution; Zinc; Brownfield; Compost; Soil recovery; Magnesite; Metal; Biochar
• ISSN: 0269-4042; 1573-2983
• DOI: 10.1007/s10653-021-00981-4

Here we addressed the remediation of a soil severely contaminated by Cu, Cd, Pb and Zn. In this regard, we tested the capacity of magnesite and biochar, inorganic and organic soil amendments, respectively, to reduce metal availability and improve soil properties. To this end, 1-kg pots containing the polluted soil were amended with either magnesite or biochar. Metal availability and soil properties were then measured at days 15 and 75. Also, to evaluate the impact of the two treatments on plant growth, we conducted experimental trials with
Brassica juncea
L. and compost addition. Both amendments, but particularly magnesite, markedly decreased metal availability. Soil properties were also enhanced, as reflected by increases in the cation exchangeable capacity. However, plant growth was inhibited by magnesite amendment. This observation could be attributable to an increase in soil pH and cation exchange capacity as well as a high Mg concentration. In contrast, biochar increased biomass production but decreased the quantity of metals recovered when the plants are harvested. In conclusion, on the basis of our results, we propose magnesite as a suitable approach for stabilizing contaminated soils (or even spoil heaps) where revegetation is not a priority. In contrast, although biochar has a lower, but still significant, capacity to immobilize metals, it can be used to restore natural soil properties and thus favor plant growth.