School of Environmental Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , China.
School of Environment and Architecture , University of Shanghai for Science and Technology , Shanghai 200093 , China.
Environ Sci Technol. 2018 Aug 7;52(15):8321-8329. doi: 10.1021/acs.est.8b00306. Epub 2018 Jul 12.
Input of biomass-derived biochar into soil is recognized as a promising method of carbon sequestration. The long-term sequestration effect of biochar depends on the stability of both its dissolvable and undissolvable fractions in soil, which could be affected by their interactions with soil minerals. Here, walnut shell-derived biochar was divided into dissolvable and undissolvable fractions and then interacted with kaolinite. Stability of kaolinite-biochar associations was evaluated by chemical oxidation and biological degradation. At low dissolvable biochar concentrations, the association was mainly attributed to "Ca bridging" and "ligand exchange", whereas "van der Waals attraction" was dominant at high concentrations. For the undissolvable biochar, kaolinite raised the activation energy of its surface by 22.1%, causing a reduction in biochar reactivity. By chemical oxidation, kaolinite reduced the C loss of total biochar by 42.5%, 33.1% resulting from undissolvable biochar and 9.4% from dissolvable biochar. Because of the presence of kaolinite, the loss of biodegradable C in total biochar was reduced by 49.4% and 48.2% from undissolvable fraction and 1.2% from dissolvable fraction. This study indicates that kaolinite can increase the stability of both dissolvable and undissolvable biochar, suggesting that kaolinite-rich soils could be a beneficial environment for biochar for long-term carbon sequestration.
生物量衍生生物炭输入土壤被认为是一种有前途的碳封存方法。生物炭的长期封存效果取决于其在土壤中可溶部分和不可溶部分的稳定性，这可能受到它们与土壤矿物质相互作用的影响。在这里，我们将核桃壳衍生生物炭分为可溶部分和不可溶部分，然后与高岭土相互作用。通过化学氧化和生物降解来评估高岭土-生物炭结合物的稳定性。在低浓度可溶生物炭的情况下，结合主要归因于“Ca 桥接”和“配体交换”，而在高浓度下则主要归因于“范德华吸引力”。对于不可溶生物炭，高岭土通过提高其表面的活化能来降低生物炭的反应性，提高了 22.1%。通过化学氧化，高岭土减少了总生物炭的 C 损失，其中 33.1%来自不可溶生物炭，9.4%来自可溶生物炭。由于高岭土的存在，总生物炭中可生物降解 C 的损失减少了 49.4%和 48.2%，分别来自不可溶部分和 1.2%来自可溶部分。这项研究表明，高岭土可以增加可溶部分和不可溶部分生物炭的稳定性，这表明富含高岭土的土壤可能是生物炭进行长期碳封存的有益环境。
