Lead immobilization in simulated polluted soil by Douglas fir biochar-supported phosphate
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Date
2021-12-16
Authors
Varco, Jac J.
Dygert, Andrew
Atsar, Felix S.
Solomon, Sabrina
Venkatesh, Rooban
Thirumalai, K.G.
Pittman Jr., Charles U.
Mlsna, Todd
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.