Genesis of podzols on coastal dunes in southern Queensland .IV . Nature of the organic fraction as seen by 13C nuclear magnetic resonance spectroscopy

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 667 ◽  
Author(s):  
JO Skjemstad ◽  
AG Waters ◽  
JV Hanna ◽  
JM Oades
Keyword(s):  
Organic Matter ◽  
Carboxylic Acid ◽  
Signal To Noise Ratio ◽  
Coastal Dunes ◽  
Resonance Spectroscopy ◽  
Organic Fraction ◽  
Aromatic Rings ◽  
13C Nuclear Magnetic Resonance ◽  
Close Proximity ◽  
Inorganic Components

The organic matter in the A, Bh, Bhs and Bs horizons from a number of profiles from a chronosequence of podzols spanning some 7x105 years was studied using solid state 13C n.m.r. spectroscopy. Organic matter was effectively concentrated without chemicals using a Spex mixer and sedimentation. Acid dithionite treatment of samples containing appreciable amounts of iron significantly improved the signal to noise ratio. Acid oxalate treatment had a lesser effect. The organic matter from the A horizon was highly aromatic but was low in carboxylic acids. In the B horizons, aromaticity decreased in the order Bh-Bhs-Bs and increased with the degree of profile development. Only in the Bh horizons of the older highly developed profiles did aromatic carbon exceed alkyl carbon. The 'core' structure of these materials appeared to be aromatic rings heavily substituted (>90%) with alkyl and carboxylic acid groups. The Bhs and Bs horizons contained substantial amounts of carboxylic acid substituted alkyls with structures similar to the polymaleic or hydroxy acid models. Sixty per cent of the organic matter removed with iron on dithionite treatment was found to be alkyl. The aromatic and alkyl dominated horizons can exist in close proximity, occurring less than 10 cm apart in the case of the giant pipey podzols. None of the current theories on podzol genesis can adequately explain the arrangement of organic and inorganic components found in these profiles and a revised model based on existing theories is proposed.

Soil organic carbon dynamics under long-term sugarcane monoculture

Soil Research ◽  
1999 ◽  
Vol 37 (1) ◽  
pp. 151 ◽  
Author(s):  
J. O. Skjemstad ◽  
J. A. Taylor ◽  
L. J. Janik ◽  
S. P. Marvanek
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Samples ◽  
Resonance Spectroscopy ◽  
13C Nuclear Magnetic Resonance ◽  
Potential Impact ◽  
Soil Organic Carbon Dynamics

Comparisons of soil samples from virgin sites or sites recently planted to sugarcane (new) with sites that had been under cane production for many years (old) were made to investigate the potential impact of cane production on soil organic carbon (OC) levels and chemistry. The comparisons showed that very little change had occurred in total OC and in ‘light’ fraction (<1·6 Mg/m3). Increasing pyrophosphate extractability throughout the profile at some sites, as a result of cultivation, however, suggested that the organic matter generally became more ‘humified’ with long-term cane production. Evidence is presented for a redistribution of OC within profiles under cane production. Old, well-established cane sites had soils with lower OC levels in the surface horizons and higher levels in the subsoils relative to new sites. The overall chemistry of the soil organic matter, as indicated by solid state 13C nuclear magnetic resonance spectroscopy, did not change significantly at each site even though between site differences were large. Some soils contained substantial amounts of charcoal which was of pre-cane origin. In some of the coarse-textured soils, smaller amounts of charcoal produced during the burning of cane appeared to accumulate below the A1 horizons in the profiles. It also appeared likely that the redistribution of carbon in the upper horizons of some soils resulted from the movement of charcoal within the profile, probably as a result of tillage.

scholarly journals Preparation of a Water-Based Photoreactive Azosulphonate-Doped Poly(Vinyl Alcohol) and the Investigation of Its UV Response

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 169 ◽  
Author(s):  
Philipp Nothdurft ◽  
Jörg Schauberger ◽  
Gisbert Riess ◽  
Wolfgang Kern
Keyword(s):  
Vinyl Alcohol ◽  
Water Solubility ◽  
Uv Spectroscopy ◽  
Poly Vinyl Alcohol ◽  
Resonance Spectroscopy ◽  
Aromatic Rings ◽  
13C Nuclear Magnetic Resonance ◽  
Vis Spectroscopy ◽  
Water Based ◽  
Uv Response

Two different azosulphonate dyes were synthesised and purified for the preparation of a water-based photoreactive azosulphonate-doped poly(vinyl alcohol). The aim was the investigation of a novel azosulphonate-poly(vinyl alcohol) photoresist with decreased water solubility after illumination, setting a focus on environmentally benign substances. The electron distribution of the aromatic rings of the two different azosulphonate molecules were changed by the UV-induced cleavage of the –N=N–SO3− groups, which was evidenced by UV spectroscopy. The formation of ester groups was detected by Fourier-transform infrared and 13C nuclear magnetic resonance spectroscopy. UV–Vis spectroscopy was used to investigate the photoreactivity of the prepared films. Photolithographic experiments demonstrated the applicability of these newly produced materials as photoresist materials. In addition, these materials provide high thermal stability.

scholarly journals Design of High Performance Scroll Microcoils for Nuclear Magnetic Resonance Spectroscopy of Nanoliter and Subnanoliter Samples

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 170
Author(s):  
Meriam Khelifa ◽  
Denis Mounier ◽  
Nourdin Yaakoubi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Electromagnetic Properties ◽  
Resonance Spectroscopy ◽  
Intrinsic Signal ◽  
Close Proximity ◽  
Nuclear Magnetic

The electromagnetic properties of scroll microcoils are investigated with finite element modelling (FEM) and the design of experiment (DOE) approach. The design of scroll microcoils was optimized for nuclear magnetic resonance (NMR) spectroscopy of nanoliter and subnanoliter sample volumes. The unusual proximity effect favours optimised scroll microcoils with a large number of turns rolled up in close proximity. Scroll microcoils have many advantages over microsolenoids: such as ease of fabrication and better B1-homogeneity for comparable intrinsic signal-to-noise ratio (SNR). Scroll coils are suitable for broadband multinuclei NMR spectroscopy of subnanoliter sample.

scholarly journals Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of Central European forests

2014 ◽  
Vol 11 (10) ◽  
pp. 15087-15107 ◽  
Author(s):  
S. Bischoff ◽  
M. T. Schwarz ◽  
J. Siemens ◽  
L. Thieme ◽  
W. Wilcke ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tree Species ◽  
Forest Floor ◽  
Resonance Spectroscopy ◽  
Total Organic Matter ◽  
Allelopathic Potential ◽  
Central European ◽  
13C Nuclear Magnetic Resonance ◽  
Structural Differences ◽  
First Time

Abstract. For the first time, we investigated the composition of dissolved organic matter (DOM) compared to total OM (TOM, consisting of DOM and particulate OM, POM) in throughfall, stemflow and forest floor leachate of beech and spruce forests using solid state 13C nuclear magnetic resonance spectroscopy. We hypothesized that the composition and properties of OM in forest ecosystem water samples differed between DOM and TOM and between the two tree species. Under beech, a contribution of phyllosphere-derived fresh POM was echoed in structural differences. Compared with DOM, TOM exhibited higher relative intensities for the alkyl C region, representing aliphatic C from less decomposed organic material, and lower relative intensities for lignin-derived and aromatic C of the aryl C region, resulting in lower aromaticity indices and reduced humification intensities. Since differences in the structural composition of DOM and TOM were less pronounced under spruce than under beech, we suspect a~tree species-related effect on the origin of OM composition and resulting properties (e.g. recalcitrance, allelopathic potential).

Incorporation of uniformly labeled 13C glucose carbon into the organic fraction of a soil - carbon balance and CP MAS 13C NMR Measurements

Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 725 ◽  
Author(s):  
JA Baldock ◽  
JM Oades ◽  
AM Vassallo ◽  
MA Wilson
Keyword(s):  
Organic Matter ◽  
Solid State ◽  
Soil Organic Matter ◽  
13C Nmr ◽  
Carbon Balance ◽  
Chemical Structure ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
13C Nuclear Magnetic Resonance ◽  
Cp Mas 13C Nmr

The incorporation of uniformly labelled 13C-giucose into soil organic matter was followed using mass spectrometry to make carbon balance measurements, and using solid state CP/MAS 13C NMR (cross polarization/magic angle spinning 13C nuclear magnetic resonance) spectroscopy to determine changes in the chemical structure of the added 13C with time. A fine sandy loam soil was incubated in the presence and absence of the labelled 13C-glucose for up to 34 days at 22�C and a soil water matric potential of -33 kPa. Carbon balance measurements indicated that no priming effect of glucose addition on decomposition of the native organic carbon occurred, and that 65% of the glucose 13C was mineralized during the incubation period. The ability of solid-state CP/MAS 13C NMR to quantitatively detect all of the substrate 13C present in the samples was assessed by comparing the residual substrate 13C contents of the samples analysed with the corresponding CP/MAS 13C NMR signal intensities. Incorporation of the glucose 13C into the soil organic matter resulted in the synthesis of alkyl (26%), O-alkyl (66%), and carboxyl (8%) carbon, but little if any aromatic carbon. The influence of decomposition processes on the chemical characteristics of the soil organic matter is discussed, and the chemical structure of the materials synthesized by the microbial biomass is compared with that of the native soil organic matter.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

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