Shi Yao, Zhang Fengjiao, Du Chengqiong, Zhao Zezhou, Zhong Yi, Li Hongbo, Hou Huijie, Wang Linling, Wu Xiaohui, Crittenden John C, Chen Jing
School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China.
Powerchina Zhongnan Engineering Corporation Limited, 16 East Cinnamomum, Changsha 410014, China.
Sci Total Environ. 2023 Mar 20;865:161265. doi: 10.1016/j.scitotenv.2022.161265. Epub 2022 Dec 29.
Field-scale trials were conducted to remove cadmium (Cd) from paddy soil by using recycled hydroxyapatite modified biochar (HBC) plus low-level CaCl washing. Synergistic reduction efficiencies of total and available Cd in soil (45.6 % and 36.8 %) were achieved by the combined amendments compared with only HBC or CaCl. The release of Cd from soil particulates was facilitated by CaCl washing and the increased soluble Cd in soil water (hardly removed by drainage) could be removed efficiently by recycled HBC adsorption. Significantly decreases in Cd translocation and accumulation in rice plants benefited from the decrease of Cd level and availability in soil and the increase of available silicon (Si). As a result, Cd contents in early/late rice grains decreased by ~85 % and met the Chinese national food standard. SOM, CEC, and soil nutrients after remediation were increased due to 10 %-15 % of HBC residual. Grain yields of the early and late rice increased by 34.1 % and 9.91 %, respectively. The collected HBC (>85 % of the total used HBC) was in-situ regenerated and could be used in the next field trials. The generated wastewater together with drainage from field treatment could be reused as irrigation water after the treatment with a small-scale reclamation ecosystem. The work provides a novelty remediation strategy for Cd-contaminated paddy soil. The noticeable remediation efficiency for Cd reduction in soil and grains, and improved productivity-relevant soil properties have important implications for paddy soil with poor fertility, severe desilicification, and Cd contamination in South China whereas the application of biochar or chemical washing alone did not.
开展了田间试验，以利用再生羟基磷灰石改性生物炭（HBC）加低水平氯化钙洗涤从稻田土壤中去除镉（Cd）。与仅使用HBC或氯化钙相比，联合改良剂实现了土壤中总镉和有效镉的协同降低效率（分别为45.6%和36.8%）。氯化钙洗涤促进了土壤颗粒中镉的释放，土壤水中增加的可溶性镉（难以通过排水去除）可通过再生HBC吸附有效去除。水稻植株中镉的转运和积累显著降低，这得益于土壤中镉水平和有效性的降低以及有效硅（Si）的增加。结果，早/晚稻籽粒中的镉含量降低了约85%，符合中国国家食品标准。由于10%-15%的HBC残留，修复后土壤中的土壤有机质、阳离子交换量和土壤养分增加。早稻和晚稻的产量分别提高了34.1%和9.91%。收集到的HBC（占使用的总HBC的85%以上）进行原位再生，可用于下一次田间试验。经过小规模回收生态系统处理后，产生的废水与田间处理的排水可作为灌溉水再利用。这项工作为镉污染稻田土壤提供了一种新颖的修复策略。在土壤和籽粒中镉降低方面显著的修复效率以及与生产力相关的土壤性质改善，对中国南方肥力差、严重脱硅和镉污染的稻田土壤具有重要意义，而单独应用生物炭或化学洗涤则没有这种效果。
