Kaolinite Enhances the Stability of the Dissolvable and Undissolvable Fractions of Biochar via Different Mechanisms,Environmental Science & Technology

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Kaolinite Enhances the Stability of the Dissolvable and Undissolvable Fractions of Biochar via Different Mechanisms
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-07-12 , DOI: 10.1021/acs.est.8b00306
Fan Yang _{1,

2} , Zibo Xu ₁ , Lu Yu ₁ , Bin Gao _{1,

3} , Xiaoyun Xu ₁ , Ling Zhao ₁ , Xinde Cao _{1,

4}

Affiliation

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 “Ca²⁺ 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.

中文翻译：

高岭石通过不同的机理增强了生物炭可溶和不可溶级分的稳定性

将源自生物质的生物碳输入土壤中被认为是一种有前途的固碳方法。生物炭的长期螯合效果取决于其可溶部分和不可溶部分在土壤中的稳定性，这可能会受到其与土壤矿物质相互作用的影响。在这里，核桃壳衍生的生物炭被分为可溶解的部分和不可溶解的部分，然后与高岭石相互作用。通过化学氧化和生物降解来评估高岭石-生物炭缔合的稳定性。在低的可溶解生物炭浓度下，该关联主要归因于“ Ca ²⁺桥联”和“配体交换”，而“范德华吸引力”在高浓度下占主导地位。对于不可溶解的生物炭，高岭石将其表面的活化能提高了22.1％，导致生物炭反应性降低。通过化学氧化，高岭石将总生物炭的碳损失减少了42.5％，其中3.％是由于不可溶生物炭造成的，而9.4％是由可溶生物炭造成的。由于高岭石的存在，总生物炭中可生物降解的C的损失从不可溶级分减少了49.4％和48.2％，从可溶级分减少了1.2％。这项研究表明，高岭石可以提高可溶解和不可溶解生物炭的稳定性，这表明富含高岭石的土壤可能是长期固碳生物炭的有利环境。

更新日期：2018-07-14

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