2020同步年報

Environmental and Earth Science 073 biochar to agricultural and ecological systems might have an enduring impact on the enrichment and transformation of SRO minerals in the soil. The distribution of BC exhibited some patchy and con- densed regions of turbostratic crystallites among the py- rogenic amorphous carbon. The core of the condensed BC region was mainly aromatic (C=C, 1604 cm -1 , Fig. 1(c) ); the distribution of reactive functional groups (1650−1730 cm -1 , Fig. 1(d) ), including carbonyl (C=O in conjunction with an aromatic ring, 1666 cm -1 ) and carboxyl groups (C=OOH, 1715 cm -1 ), were mostly in the peripheral region of the aro- matic C. The distribution of the clay minerals (lattice water O−H, 3550−3750 cm -1 ) was by and large correlated with the presence of reactive functional groups on BC ( Figs. 1(c)– (e) ). Fe-minerals and Ca-minerals had a spatial correlation with BC. The broad and pronounced lines within spectral ranges 1200−1400 cm -1 and 1650−1730 cm -1 in BC indicat- ed a significant level of organo-mineral complexation ( Figs. 1(a), 1(c) and 1(e) ). A strong signal from the phenolic func- tional groups (aryl−OH) was observed at 1241 cm -1 ( Figs. 1(a) and 1(e) ). A line at 1380–1384 cm -1 was identified for the inner-sphere complexation of Fe and aromatic C ( Fig. 1(a) ). 1 Overall, SRO ferrihydrite and amorphous Fe-phases were more abundant in ADE than in the adjacent soil. Among the poorly crystalline phases, ferrihydrite was highly enriched in the BC particles. The µFTIR spectra of pyrogenic amorphous carbon were acquired by using infrared micro- spectroscopy endstation at TLS 14A1 . A larger CN denoted a greater degree of order in the coordination between neighboring Fe mineral crystals, re- sulting from the enrichment of SRO minerals in BC. A small but distinct feature was observed at 5.7 Å -1 in the EXAFS k oscillation of BC, corresponding to single scattering of the Fe−C bond (including Fe−O−C). 2 A weak shoulder at 5–5.2 Å -1 , a shoulder signal at 7.5 Å -1, and a small signal at 9.5 Å -1 were observed in BC, corresponding to the weak high-shell backscattering signal and the presence of ferrihydrite and ferrihydrite-like Fe domains. ( Fig. 2 ). The findings of Biqing Liang (National Cheng Kung Univer- sity) and her collaborators enabled a strong appeal that the complicated interplay between BC aging-driven surface modifications and SRO minerals might play an important role in the enduring stabilization of BC. Their research argues that both the interactive chemistry between BC and the associated minerals and their physical presence are important for the enduring stabilization of organic carbon. The enrichment of poorly crystalline minerals such as SRO ferrihydrite can have a positive feedback on the enduring stabilization of BC. Biochar applications enrich SRO minerals in the soil; these, in turn, enhance the stabilization of BC. Systematic investigations are required to understand the qualitative and quantitative correlations between SRO min- erals and soil organic-carbon storage at the modeling level. Perspectives on soil carbon stabilization and saturation might be revolutionized once the key role of SRO minerals is taken into carbon models, beyond the traditional param- eters, such as clay type and content. (Reported by Biqing Liang, National Cheng Kung University) This report features the work of Biqing Liang and her collab- orators published in Sci. Total Environ. 725 , 138195 (2020). TPS 21A X-ray Nanodiffraction TLS 01B1 SWLS − X-ray Microscopy TLS 14A1 BM − IR Microscopy TLS 16A1 BM Tender X-ray Absorption, Diffraction TLS 17C1 W200 − EXAFS • TXM, FITR, EXAFS • Chemistry, Environmental and Earth Science References 1. T. D. Sowers, J. W. Stuckey, D. L. Sparks, Geochem. Trans. 19 , 4 (2018). 2. W. Z. Tamrat, J. Rose, O. Grauby, E. Doelsch, C. Levard, P. Chaurand, I. Basile-Doelsch, Geochim. Cosmochim. Acta 260 , 15 (2019). 3. Y.-T. Weng, J. Rathod, B. Liang, C.-C. Wang, Y. Iizuka, N. Tamura, C.-L. Chen, Y.-C. Lee, Sci. Total Environ. 725 , 138195 (2020). Fig. 2 : Fe-EXAFS k oscillation for BC, ADE and adjacent soil. The green arrows mark the shoulder and signal at 5.2, 7.5 and 9.5 Å, indicat- ing the presence of ferrihydrite. The blue arrow points to a small feature at 5.7 Å, which is characteristic of Fe-O-C bonds. [Repro- duced from Ref. 3]