Lead immobilization in simulated polluted soil by Douglas fir biochar-supported phosphate
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Date
2021-12-16
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier Chemosphere
Abstract
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 < 7 through dissolution of hydroxyapatite embedded
in BP during modification, followed by precipitation of insoluble Pb10(PO4)6(OH)2. The residual lead fraction in
the lead-spiked soil increased by 20.9% following amendment with BP. These results indicate that biocharsupported phosphate is a candidate to reduce lead mobility (bioavailability) in polluted soil. This amendment
may lower Pb2+ uptake into plants while minimizing the potential for water contamination due to Pb2+mobility.
Description
Arwenyo_lead_article_2022
Keywords
Heavy metals, Biochar supported-phosphate, In-situ-immobilization, Bioavailability, Soil pollution
Citation
Beatrice, A., Varco, J. J., Dygert, A., Atsar, F. S., Solomon, S., Thirumalai, R. V. K., ... & Mlsna, T. (2022). Lead immobilization in simulated polluted soil by Douglas fir biochar-supported phosphate. Chemosphere, 292, 133355.