Research Center for Coastal Environment Engineering Technology of Shandong Province, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China; University of Chinese Academy of Sciences, Beijing, China.
Research Center for Coastal Environment Engineering Technology of Shandong Province, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
Sci Total Environ. 2020 Apr 15;713:136650. doi: 10.1016/j.scitotenv.2020.136650. Epub 2020 Jan 15.
Remediation of Cd pollution in sediments is crucial for the safety of aquatic environments and human health. In this study, four effective, common, and low-cost remediation materials (zeolite, sepiolite, red mud (RM), and biochar (BC)) loaded with nanoscale zero-valent iron (nZVI) and themselves were employed to immobilize Cd in sediments. The effects of different materials on sediment properties, immobilization effectiveness, bacterial communities, enzyme activities, and dissolved organic matter (DOM) were investigated. Results showed that sediment properties were significantly changed by the addition of immobilization materials (P < 0.05). The geochemical fraction analysis showed that the labile Cd was partially transformed to the stable fraction after immobilization, with an 11-47% decrease in the acid-soluble fraction and a 50-1000% increase in the residual fraction. The Cd immobilization effectiveness peaked at the nZVI/RM and nZVI/BC treatments, and the Cd toxicity characteristic leaching procedure (TCLP) leachabilities decreased by 42% and 44%, respectively. The modified materials were more effective for immobilizing Cd than the raw materials owing to the presence of nZVI, and the Cd TCLP leachabilities with the modified materials decreased by 15%-22% compared with the raw material treatments. Immobilization-driven reduction of bioavailable Cd enhanced the richness and diversity of bacterial communities and enzyme activities. Moreover, the immobilization treatment promoted the Fe(III)-reducing process by increasing the Fe(III)-reducing bacteria (e.g. Geobacteraceae, Bacillus, and Clostridium), which are conducive to Cd immobilization. Additionally, the DOM composition presented more autogenetic characteristics in treated groups. BC (nZVI/BC) can be selected as the priority material for Cd immobilization in sediments due to higher immobilization effectiveness and lower adverse effects on sediments.
修复沉积物中的 Cd 污染对于水环境保护和人类健康至关重要。本研究采用沸石、海泡石、赤泥（RM）和生物炭（BC）四种常用且廉价的修复材料负载纳米零价铁（nZVI）及其本身，用于固定沉积物中的 Cd。考察了不同材料对沉积物性质、固定效果、细菌群落、酶活性和溶解有机质（DOM）的影响。结果表明，添加固定材料后，沉积物性质发生了显著变化（P<0.05）。地球化学形态分析表明，固定化后部分可交换态 Cd 转化为稳定态，酸可提取态 Cd 减少了 11-47%，残渣态 Cd 增加了 50-1000%。nZVI/RM 和 nZVI/BC 处理的 Cd 固定效果最佳，Cd 毒性特征浸出程序（TCLP）浸出率分别降低了 42%和 44%。与原始材料相比，改性材料由于含有 nZVI，对 Cd 的固定效果更好，改性材料处理的 Cd TCLP 浸出率比原始材料处理的降低了 15%-22%。可利用 Cd 的减少促进了细菌群落和酶活性的丰富度和多样性的提高。此外，固定化处理通过增加铁还原菌（如 Geobacteraceae、芽孢杆菌和梭菌）来促进 Fe(III)-还原过程，这有利于 Cd 的固定。此外，处理组中的 DOM 组成呈现出更多的自生特征。由于具有更高的固定效果和对沉积物的不利影响较低，BC（nZVI/BC）可被选为沉积物中 Cd 固定的首选材料。
