Xie Shengyu, Yu Guangwei, Ma Jianli, Wang Gang, Wang Qichuan, You Futian, Li Jie, Wang Yin, Li Chunxing
CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.
CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
Environ Res. 2020 Dec;191:110188. doi: 10.1016/j.envres.2020.110188. Epub 2020 Sep 11.
Potentially toxic elements in municipal sewage sludge can be effectively immobilized during biochar production via pyrolysis. However, the bioavailability of these elements when biochar is applied in soilless cultivation to improve substrate quality has yet to be sufficiently established. In this study, we investigated the chemical speciation and cucumber plant uptake of potentially toxic elements in soilless cultivation when the growth substrate was amended with sewage sludge biochar (0, 5, 10, 15, and 20 wt%). It was found that the addition of 10 wt% biochar was optimal with respect to obtaining a high cucumber biomass and achieving low environmental risk considering the occurrence of hormesis. When the substrate was amended with 10 wt% biochar, cucumber fruit contained lower concentrations of As, Cr, and Zn and smaller bioavailable fractions of As, Cd, Cr, Ni, Cu, and Zn compared with the fruit of control plants, thereby meeting national safety requirements (standard GB 2762-2012, China). Most of the As and Cd taken up by cucumbers accumulated in the leaves and fruit, whereas Cr was found primarily in the roots, and most Ni, Cu, and Zn was detected in the fruit. Importantly, only small proportions of the potentially toxic elements in biochar were taken up by cucumber plants (As: 0.0075%; Cd: 0.038%; Ni: 0.0064%; Cu: 0.0016%; and Zn: 0.0015%). Given that the As, Cd, Ni, and Zn speciation in sewage sludge biochar was effectively immobilized after cultivation, the findings of this study indicate that sewage sludge biochar is a suitable substrate amendment in terms of the risk posed by potentially toxic elements.
城市污水污泥中的潜在有毒元素可在通过热解生产生物炭的过程中得到有效固定。然而，当生物炭应用于无土栽培以改善基质质量时，这些元素的生物有效性尚未得到充分证实。在本研究中，我们调查了在无土栽培中，当生长基质用污水污泥生物炭（0、5、10、15和20 wt%）改良时，潜在有毒元素的化学形态以及黄瓜植株对这些元素的吸收情况。研究发现，考虑到刺激效应的发生，添加10 wt%的生物炭对于获得高黄瓜生物量和实现低环境风险是最佳的。当基质用10 wt%的生物炭改良时，与对照植株的果实相比，黄瓜果实中砷、铬和锌的含量较低，砷、镉、铬、镍、铜和锌的生物可利用部分较小，从而符合国家安全要求（中国国家标准GB 2762 - 2012）。黄瓜吸收的大部分砷和镉积累在叶片和果实中，而铬主要存在于根部，大部分镍、铜和锌则在果实中被检测到。重要的是，黄瓜植株仅吸收了生物炭中一小部分潜在有毒元素（砷：0.0075%；镉：0.038%；镍：0.0064%；铜：0.0016%；锌：0.0015%）。鉴于污水污泥生物炭中的砷、镉、镍和锌形态在栽培后得到有效固定，本研究结果表明，就潜在有毒元素带来的风险而言，污水污泥生物炭是一种合适的基质改良剂。
