Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Sci Total Environ. 2017 Dec 1;601-602:1015-1023. doi: 10.1016/j.scitotenv.2017.05.256. Epub 2017 Jun 9.
The aim of this study was to reveal the mechanisms on how biochar reduces bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in tuberous vegetables. Corn straw-derived biochar pyrolyzed at 300°C (CB300) or bamboo-derived biochar pyrolyzed at 700°C (BB700) was amended into PAH-contaminated soil planted with carrot (Daucus carota L.). After 150days, 2% CB300 or 2% BB700 amendments significantly reduced the bioaccumulation of PAHs in carrot root (p<0.05), especially for high-molecular-weight PAHs. In the non-rhizosphere, either CB300 or BB700 suppressed PAH dissipation and decreased the bioavailability via adsorption processes. Compared to the control, the total concentration of PAHs in the rhizosphere was higher in the 2% BB700 treatment but the bioavailable concentration was lower. This indicates that BB700 decreased the bioavailability of PAHs primarily via immobilization (adsorption processes). By contrast, the total and bioavailable PAH concentrations were both lower in the 2% CB300 treatment than those in the control. The abundance of bacteria such as Arthrobacter and Flavobacterium and the total number of genes playing important roles in microbial PAH degradation processes increased significantly (p<0.05), which were likely responsible for the rapid dissipation of PAHs in the 2% CB300 treatment in the rhizosphere. These results indicate that CB300 decreased the PAH bioavailability primarily via increasing degradation of PAHs by indigenous microorganisms. The two biochars both showed better effectiveness at reducing the bioavailability of high-molecular-weight PAHs than the low-molecular-weight PAHs in the rhizosphere. Therefore, the mechanisms on how biochar reduces the PAH uptake into carrot are dependent on the type of biochar (e.g., pyrolysis temperature and feedstock) and root presence.
本研究旨在揭示生物炭降低块茎类蔬菜中多环芳烃（PAHs）生物累积的机制。将在 300°C 热解的玉米秸秆生物炭（CB300）或在 700°C 热解的竹材生物炭（BB700）添加到种植胡萝卜（Daucus carota L.）的受 PAHs 污染的土壤中。150 天后，2% CB300 或 2% BB700 添加剂显著降低了胡萝卜根部的 PAHs 生物累积（p<0.05），特别是高分子量 PAHs。在非根际区，CB300 或 BB700 均通过吸附过程抑制 PAH 降解并降低其生物可利用性。与对照相比，2% BB700 处理的根际中 PAHs 的总浓度较高，但生物可利用浓度较低。这表明 BB700 主要通过固定化（吸附过程）降低 PAHs 的生物可利用性。相比之下，2% CB300 处理的总 PAH 和生物可利用 PAH 浓度均低于对照。在根际中，细菌如节杆菌属和黄杆菌属的丰度以及在微生物 PAH 降解过程中发挥重要作用的基因总数显著增加（p<0.05），这可能是 2% CB300 处理中 PAHs 快速降解的原因。这些结果表明，CB300 主要通过增加土著微生物对 PAHs 的降解来降低 PAH 的生物可利用性。两种生物炭在降低根际中高分子量 PAHs 的生物可利用性方面均优于低分子量 PAHs。因此，生物炭降低胡萝卜对 PAH 吸收的机制取决于生物炭的类型（例如，热解温度和原料）和根的存在。
