Biochar Engineering Technology Research Center of Guangdong Province, School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China; University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany.
Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China.
Environ Int. 2021 Nov;156:106628. doi: 10.1016/j.envint.2021.106628. Epub 2021 May 12.
Functionalized biochar has gained extensive interests as a sustainable amendment for an effective remediation of paddy soils contaminated with heavy metals (HMs). We examined the efficiency of pig carcass-derived biochar (P-rich biochar, total P = 8.3%) and pristine (raw biochar, total Fe = 0.76%) and Fe-modified (Fe-rich biochar, total Fe = 5.5%) green waste-derived biochars for the immobilization of cadmium (Cd) and lead (Pb) in a paddy soil under pre-defined redox conditions (Eh, from -400 to +300 mV). Average concentrations (μg L) of dissolved Cd increased under reducing conditions up to 10.9 in the control soil, and decreased under oxidizing conditions to below the detection limit (LDL = 2.7) in the raw and Fe-rich biochar treated soils. Application of the raw biochar decreased the concentrations of dissolved Cd by 43-59% under Eh ≤ -100 mV, compared to the non-treated control, which was more effective than the Fe-rich biochar (31-59%) and the P-rich biochar (8-19%). The immobilization of Cd under low Eh might be due to its precipitation with sulfide (S), whereas its immobilization under high Eh might be due to the associated increase of pH. Concentrations (μg L) of Pb ranged from 29.4 to 198.2 under reducing conditions, and decreased to LDL (12.5) under oxidizing conditions. The P-rich biochar was more effective in immobilizing Pb than the raw and Fe-rich biochars, particularly under Eh ≤ 0 mV (55-82%), which might be due to the retention of Pb by phosphates. The raw and Fe-rich biochars immobilized Pb under low Eh (≤ -300 mV), but both biochars, particularly the Fe-rich biochar mobilized Pb under Eh higher than -200 mV, especially at +100 mV, due to the decrease of pH at this point (pH = 6.0 to 6.5). These results improved our understanding of using P-rich and Fe-rich functionalized biochars for the immobilization of Cd and Pb in a paddy soil under stepwise redox changes. The amendment of P-rich pig carcass-derived biochar to paddy soils could be a promising approach for mitigating the risk of Pb for human health and the environment. The raw and Fe-rich green waste-derived biochars can be used for immobilizing Cd and mitigating its risk in paddy soils under both reducing and oxidizing conditions.
功能化生物炭作为一种可持续的改良剂，在有效修复重金属（HM）污染的稻田方面引起了广泛关注。我们研究了猪尸源生物炭（富磷生物炭，总磷= 8.3%）和原始（生生物炭，总铁= 0.76%）和铁改性（富铁生物炭，总铁= 5.5%）绿色废物源生物炭对镉（Cd）和铅（Pb）在预定义氧化还原条件（Eh，从-400 到+300 mV）下在稻田中的固定化效率。在还原条件下，对照土壤中溶解态 Cd 的浓度增加到 10.9μg/L，而在氧化条件下，原始和富铁生物炭处理的土壤中 Cd 的浓度降至检测限以下（LDL=2.7）。与未处理的对照相比，在 Eh≤-100 mV 下，原始生物炭的应用使溶解态 Cd 的浓度降低了 43-59%，这比富铁生物炭（31-59%）和富磷生物炭（8-19%）更有效。在低 Eh 下 Cd 的固定可能是由于其与硫化物（S）的沉淀，而在高 Eh 下 Cd 的固定可能是由于 pH 的升高。在还原条件下，Pb 的浓度范围为 29.4 至 198.2μg/L，在氧化条件下降至 LDL（12.5μg/L）。富磷生物炭比原始和富铁生物炭更有效地固定 Pb，特别是在 Eh≤0 mV（55-82%）时，这可能是由于磷酸盐对 Pb 的保留。原始和富铁生物炭在低 Eh（≤-300 mV）下固定 Pb，但两种生物炭，特别是富铁生物炭，在 Eh 高于-200 mV 下固定 Pb，特别是在+100 mV 时，因为此时 pH 下降（pH=6.0 至 6.5）。这些结果提高了我们对在逐步氧化还原变化下使用富磷和富铁功能化生物炭固定 Cd 和 Pb 来固定 Cd 和 Pb 的理解。向稻田中添加富磷猪尸源生物炭可能是减轻 Pb 对人类健康和环境风险的一种有前途的方法。原始和富铁的绿色废物源生物炭可用于在还原和氧化条件下固定 Cd 并减轻其在稻田中的风险。
