College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province, 712100, China.
China Nonferrous Metal Industry Xi 'an Survey and Design Institute Co., LTD, Xian, Shaanxi Province, 710054, China.
J Environ Manage. 2024 Jun;361:121231. doi: 10.1016/j.jenvman.2024.121231. Epub 2024 May 28.
Insitu stabilization and phytoextraction are considered as two convenient and effective technologies for the remediation of toxic elements (TEs) in soils. However, the effectiveness of these two remediation technologies together on the bioavailability and phytoextraction of TEs in field trials has not been explored yet. Specifically, the remediation potential of fly ash (FA; as stabilizing agent) and ryegrass (as a TE accumulator) intercropped with a target crop for soil polluted with multiple TEs has not been investigated yet, particularly in long-term field trials. Therefore, in this study, a six-month combined remediation field experiment of FA stabilization and/or ryegrass intercropping (IR) was carried out on the farmland soils contaminated with As, Cd, Cr, Cu, Hg, Ni, Pb and Zn where Zanthoxylumbungeanum (ZB) trees as native crops were grown for years. The treatments include soil cultivated alone with ZB untreated- (control) and treated-with FA (FA), produced by burning lignite in Shaanxi Datong power plant, China, soil cultivated with ZB and ryegrass untreated- (IR) and treated-with FA (FA + IR). This was underpinned by a large-scale survey in Daiziying (China), which showed that the topsoils were polluted by Cd, Cu, Hg and Pb, and that Hg and Pb contents in the Zanthoxylumbungeanum fruits exceeded their allowable limits. The TEs contents in the studied FA were lower than their total element contents in the soil. The DTPA-extractable TEs contents of the remediation modes were as follows: FA < FA + IR < IR < control. Notably, TEs contents in the ZB fruits were lowest under the FA + IR treatment, which were decreased by 27.6% for As, 42.3% for Cd, 16.7% for Cr, 30.5% for Cu, 23.1% for Hg, 15.5% for Ni, 33.2% for Pb and 38.1% for Zn compared with the control treatment. Whereas the FA + IR treatment enhanced TEs contents in ryegrass shoots and roots, and the TEs contents in ryegrass shoots were below their regulatory limits for fodder crops. The findings confirmed that the combined remediation strategy, i.e., FA (with low content of TEs) stabilization effect and intercropping of ZB (target crop) and ryegrass (accumulating plant) could provide a prospective approach to produce target plants within safe TEs thresholds with greater economic benefits, while remediating soils polluted with multiple TEs and mitigating the potential ecological and human health risk. Those results are of great applicable concern.
原位稳定和植物提取被认为是修复土壤中有毒元素（TEs）的两种方便有效的技术。然而，这两种修复技术在田间试验中对 TEs 的生物有效性和植物提取的协同作用尚未得到探索。具体来说，尚未研究在农田土壤中同时使用粉煤灰（FA；作为稳定剂）和黑麦草（作为 TEs 积累者）与目标作物修复受多种 TEs 污染的修复潜力，尤其是在长期田间试验中。因此，在这项研究中，在中国陕西大同火力发电厂燃烧褐煤产生的 FA 稳定和/或黑麦草间作（IR）的为期六个月的联合修复田间实验在种植多年花椒树（ZB）的农田土壤上进行。处理包括单独用未经处理的花椒（对照）和用 FA（FA）处理的土壤，FA 是在中国陕西大同火力发电厂燃烧褐煤产生的，用未经处理的黑麦草（IR）和用 FA 处理的土壤种植花椒和黑麦草（FA+IR）。这是在中国代子营进行的一项大规模调查的基础，该调查显示，表层土壤受到 Cd、Cu、Hg 和 Pb 的污染，花椒果实中的 Hg 和 Pb 含量超过了允许限值。研究中 FA 的 TEs 含量低于土壤中总元素含量。修复模式下的 DTPA 可提取 TEs 含量如下：FA<FA+IR<IR<对照。值得注意的是，FA+IR 处理下 ZB 果实中的 TEs 含量最低，与对照处理相比，As 降低了 27.6%，Cd 降低了 42.3%，Cr 降低了 16.7%，Cu 降低了 30.5%，Hg 降低了 23.1%，Ni 降低了 15.5%，Pb 降低了 33.2%，Zn 降低了 38.1%。然而，FA+IR 处理增加了黑麦草地上部分和地下部分的 TEs 含量，并且黑麦草地上部分的 TEs 含量低于饲料作物的监管限值。研究结果证实，FA（TEs 含量低）稳定效应与 ZB（目标作物）和黑麦草（积累植物）间作的联合修复策略可以为在安全 TEs 阈值内生产目标植物提供一种有前景的方法，同时修复受多种 TEs 污染的土壤并减轻潜在的生态和人类健康风险。这些结果具有重要的应用意义。
