Global Centre for Environmental Remediation (GCER), Advanced Technology Center (ATC) Building, Faculty of Science, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
Global Centre for Environmental Remediation (GCER), Advanced Technology Center (ATC) Building, Faculty of Science, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
Sci Total Environ. 2018 Jan 1;610-611:1457-1466. doi: 10.1016/j.scitotenv.2017.08.228. Epub 2017 Sep 5.
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 (50mg/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 (CaCl 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.
本研究旨在探讨不同性质土壤中酸性和中性生物炭对镉（Cd）溶解度和生物有效性的影响。将 5%的酸性木屑生物炭（WS，pH=3.25）和中性鸡粪生物炭（CL，pH=7.00）添加到 4 种 Cd 污染（50mg/kg）土壤（EN：灰土、AL：淋溶土、VE：变性土、IN：始成土）中。经过 140 天的培养，评估了镉的溶解度和生物有效性/生物可及性。结果表明，两种生物炭都不能降低高吸附能力土壤（AL、IN）中可溶（孔隙水）和可利用（CaCl 可提取）的 Cd，而 CL 生物炭降低了低吸附能力土壤（EN、VE）中可溶和可利用的 Cd，降低幅度约为 50%。酸性 WS 生物炭对 Cd 的人体胃相（基于生理的提取试验（PBET）可提取）的生物可及性没有影响，但中性 CL 生物炭降低了 AL、EN、IN 和 VE 土壤的生物可及性分别为 18.8%、29.7%、18.0%和 8.82%。两种生物炭均显著降低了所有土壤中酸性条件下（毒性特征浸出程序（TCLP）可提取）的可溶 Cd。土壤中 Cd 溶解度的控制因素是孔隙水 pH 值。CL 生物炭降低 Cd 溶解度和生物有效性/生物可及性的原因可能是表面络合，而两种生物炭在酸性条件下（TCLP）降低 Cd 的迁移性可能是由于 Cd 重新分配到生物利用性较低的土壤固体部分。因此，如果只需要减轻酸性条件下 Cd 的浸出，应用低 pH 值的生物炭（如 WS 生物炭）可能是有价值的。
