Lead immobilization in simulated polluted soil by Douglas fir biochar-supported phosphate

• Published in: Chemosphere (Oxford) 2022-04, Vol.292, p.133355-133355, Article 133355
• Main Authors: Beatrice, Arwenyo, Varco, Jac J., Dygert, Andrew, Atsar, Felix S., Solomon, Sabrina, Thirumalai, Rooban Venkatesh K.G., Pittman Jr, Charles U., Mlsna, Todd
• Format: Article
• Language: English
• Subjects: Bioavailability; Biochar supported-phosphate; Charcoal; Heavy metals; In-situ-immobilization; Lead; Phosphates; Pseudotsuga; Soil; Soil Pollutants - analysis; Soil pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2021.133355

This study compared the lead (Pb2+) immobilization efficacy of biochar-supported phosphate to conventional in-situ heavy metal immobilization methods (with lime, neat biochar and phosphate). The biochar-supported phosphate was obtained by treating Douglas fir biochar (BC) with anhydrous calcium chloride and potassium dihydrogen phosphate. The amount of Pb2+ immobilized was determined by comparing the concentration of ammonium nitrate extractable Pb2+ lead from lead-spiked soil (without amendment) to that of a 30 d incubation with (a) lead-spiked soil plus 5% (wt./wt.) biochar supported-phosphate, (b) lead-spiked soil plus 5% (wt./wt.) untreated Douglas fir biochar, (c) lead-spiked soil plus 5% (w/w) lime and (d) lead-spiked soil plus 5% (wt./wt.) potassium dihydrogen phosphate. The control (lead-spiked soil without amendment) produced the largest quantity (96.08 ± 9.22 mg L−1) of NH4NO3-extractable Pb2+, while lead-spiked soil treated with 5% (wt./wt.) biochar-supported phosphate resulted in the lowest quantity of NH4NO3 extractable Pb2+ (0.3 ± 0.2 mg L−1). The mechanism for immobilization of Pb2+ by BP occurs at pH