Abstract
This study was designed to investigate the effects of acidic and neutral biochars on solubility and bioavailability of cadmium (Cd) in soils with contrasting properties. Four Cd contaminated (50 mg/kg) soils (EN: Entisol, AL: Andisol, VE: Vertisol, IN: Inceptisol) were amended with 5% acidic wood shaving biochar (WS, pH = 3.25) and neutral chicken litter biochar (CL, pH = 7.00). Following a 140-day incubation, the solubility and bioavailability/bioaccessibility of cadmium (Cd) were assessed. Results showed that both biochars had no effect on reducing soluble (pore water) and bioavailable (CaCl2 extractable) Cd for higher sorption capacity soils (AL, IN) while CL biochar reduced those in lower sorption capacity soils (EN, VE) by around 50%. Bioaccessibility of Cd to the human gastric phase (physiologically based extraction test (PBET) extractable) was not altered by the acidic WS biochar but reduced by neutral CL biochar by 18.8%, 29.7%, 18.0% and 8.82% for soil AL, EN, IN and VE, respectively. Both biochars reduced soluble Cd under acidic conditions (toxicity characteristic leaching procedure (TCLP) extractable) significantly in all soils. Pore water pH was the governing factor of Cd solubility among soils. The reduction of Cd solubility and bioavailability/bioaccessibility by CL biochar may be due to surface complexation while the reduced mobility of Cd under acidic conditions (TCLP) by both biochars may result from the redistribution of Cd to less bioavailable soil solid fractions. Hence, if only leaching mitigation of Cd under acidic conditions is required, application of low pH biochars (e.g., WS biochar) may be valuable.
Original language | English |
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Pages (from-to) | 1457-1466 |
Number of pages | 10 |
Journal | Science of the Total Environment |
Volume | 610-611 |
DOIs | |
Publication status | Published - 2018 Jan 1 |
Bibliographical note
Funding Information:We acknowledge M.A.H. Johir from Center for Technology in Water and Wastewater, University of Technology, Sydney for DOC and anion analysis, the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment ( CRC CARE ) for financial support.
Publisher Copyright:
© 2017 Elsevier B.V.
Keywords
- Bioaccessibility
- Bioavailability
- Leaching
- PBET
- Surface complexation
- TCLP
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Pollution