生物炭对植物的促进作用取决于热解温度，但对金属的固定作用则取决于残留生物炭。
Biochar DOM for plant promotion but not residual biochar for metal immobilization depended on pyrolysis temperature.
机构信息
Institute of Resources, Ecosystem and Environment of Agriculture and Center of Biomass and Biochar Green Technology, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China.
Institute of Resources, Ecosystem and Environment of Agriculture and Center of Biomass and Biochar Green Technology, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, China; School of Materials Science & Engineering, University of New South Wales, Australia.
出版信息
Sci Total Environ. 2019 Apr 20;662:571-580. doi: 10.1016/j.scitotenv.2019.01.224. Epub 2019 Jan 22.
While biochar on metal immobilization was well understood, a small pool of dissolvable organic matter (DOM) from biochar was recently recognized as a bioactive agent for plant growth promotion. However, how the molecular composition and plant effects of this fraction and the performance for metal immobilization of the DOM-removed biochar could vary with pyrolysis temperature had been not well addressed. In this study, wheat straw biochar pyrolyzed at a temperature of 350 °C, 450 °C, 550 °C were extracted with hot water to separate the DOM fraction. The obtained biochar extracts (BE350, BE450, and BE550) were tested as foliar amendment to Chinese cabbage while the extracted (DOM-removed) biochars were tested for heavy metal immobilization in a contaminated soil. The results showed that BE350 was higher in organic matter content, abundance of organic molecules and mineral nutrients than BE450 and BE550. Compared to control, foliar application of BE350 significantly enhanced the shoot biomass (by 89%), increased leaf soluble sugar content (by 83%) but reduced leaf content of nitrate (by 34%) and of potential toxic metals (by 49% for Cd and by 30% for Pb). Moreover, BE350 treatment increased gene expression of nitrate reductase and glutamine synthetase enzyme activity of the tested plant. Meanwhile, soil amendment of DOM-extracted biochars significantly decreased soil CaCl extractable pool of Cd, Pb, Cu and Zn in a range of 27%-78%. Thus, the performance of DOM extract of biochar on plant growth promotion was indeed dependent of pyrolysis temperature, being greater at 350 °C than at higher temperatures. In contrast, metal immobilizing capacity of biochar was regardless of pyrolysis temperature and DOM removal. Therefore, pyrolyzing wheat straw at low temperature could produce a biochar for valorized separation of a significant DOM pool for use in vegetable production, leaving the residual biochar for amendment to metal contaminated soil.
虽然生物炭对金属固定化的作用已经得到很好的理解，但最近人们认识到生物炭中一小部分可溶解的有机物（DOM）是一种促进植物生长的生物活性物质。然而，这种DOM 去除生物炭的分子组成和植物效应以及金属固定化性能如何随热解温度的变化而变化，尚未得到很好的解决。在这项研究中，将温度为 350°C、450°C 和 550°C 的小麦秸秆生物炭进行热解，用热水提取以分离 DOM 部分。获得的生物炭提取物（BE350、BE450 和 BE550）被用作小白菜的叶面添加剂，而提取的（DOM 去除）生物炭则被用于受污染土壤中重金属的固定化。结果表明，BE350 的有机质含量、有机分子丰度和矿质养分含量均高于 BE450 和 BE550。与对照相比，叶面喷施 BE350 显著提高了地上生物量（增加 89%），增加了叶片可溶性糖含量（增加 83%），但降低了叶片硝酸盐含量（减少 34%）和潜在有毒金属含量（Cd 减少 49%，Pb 减少 30%）。此外，BE350 处理增加了被测试植物硝酸还原酶和谷氨酰胺合成酶基因表达和酶活性。同时，DOM 提取生物炭的土壤添加显著降低了土壤中 Cd、Pb、Cu 和 Zn 的 CaCl2 可提取量，范围为 27%-78%。因此，生物炭 DOM 提取物对植物生长促进的性能确实依赖于热解温度，在 350°C 时比在更高温度时更大。相比之下，生物炭的金属固定能力与热解温度和 DOM 去除无关。因此，在低温下热解小麦秸秆可以产生一种生物炭，用于有价值地分离出大量的 DOM 池，用于蔬菜生产，而将剩余的生物炭用于受金属污染的土壤改良。
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