کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4575642 | 1629560 | 2006 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Characterization of allophanic Andisols by solid-state 13C, 27Al, and 29Si NMR and by C stable isotopic ratio, δ13C Characterization of allophanic Andisols by solid-state 13C, 27Al, and 29Si NMR and by C stable isotopic ratio, δ13C](/preview/png/4575642.png)
Three representative allophanic Andisols in Japan were evaluated by solid-state 13C, 27Al, and 29Si nuclear magnetic resonance (NMR) and stable isotopic ratio of carbon (δ13C). The solid-state cross polarization magic angle spinning (CPMAS) 13C NMR spectra were effective in characterizing crude soil C without any chemical treatment when soil C content was > 100 g C kg− 1. Aliphatic, O-alkyl, and carbonyl C were relatively abundant in the uppermost horizons, whereas aromatic C was concentrated in the subsurface horizons, showing its persistence and tolerance to degradation in subsurface horizons. Contribution ratios of C4-plant-derived C (mainly from Miscanthus sinensis) on the total CRC4 which were evaluated from δ13C value, were 35% to 42%, 59% to 62%, and 50% to 53% in subsurface horizons, and 12%, 23%, and 48% in uppermost horizons, for the three soils. The decline in CRC4 values in the uppermost horizons could be an effect of recent vegetation. Solid-state 27Al and 29Si NMR revealed that most part of the tetrahedral Al in volcanic glass had already weathered into octahedral Al and a large amount of allophanic constituents (allophane, imogolite, allophane-like constituents including protoimogolite) was formed in B horizon within the past 25,000 14C y. Allophanic constituents determined by 29Si NMR were compared with those dissolved by acid-oxalate, and differences between them were discussed.
Journal: Geoderma - Volume 136, Issues 3–4, 15 December 2006, Pages 696–707