Poly(methylene) Crystallites in Humic Substances Detected by Nuclear Magnetic Resonance

Hu, Weiguo; Mao, Jingdong; Xing, Baoshan; Schmidt‐Rohr, Klaus

doi:10.1021/es990506l

Cited by 191 publications

(169 citation statements)

References 31 publications

Supporting

Mentioning

153

Contrasting

Unclassified

Order By: Relevance

“…First, the enhanced desorption resistance of PAHs in DHS may merit alternative mechanistic interpretations other than partitioning concept because of the structural heterogeneity of HA. Hu et al found that crystalline polyethylene-like domains existed in HA and proposed that the presence of the poly(methylene)crystallites may contribute specific properties [37]. Dissolved HA has been proved to contain semimicelle or pseudomicelle structures even below the critical micelle concentration [38].…”

Section: Possible Mechanisms Contributing To Desorption Resistancementioning

confidence: 99%

Aging effects on sorption–desorption behaviors of PAHs in different natural organic matters

Wang

Chen

et al. 2012

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

a b s t r a c tThe aging effects of sorption-desorption of two polycyclic aromatic hydrocarbons (PAHs), that is, phenanthrene and chrysene on different natural organic matters (NOMs), that is, humic acid, fulvic acid, and humins of different sources were studied. Both organic carbon-normalized distribution coefficients (K oc ) and the reversible desorption fractions (f rd ) were evaluated. Results showed that aging effects were both sorbent and sorbate specific. With increasing aging duration, K oc s of phenanthrene on humins increased, whereas K oc s of chrysene did not change significantly. Significant f rd declinations over aging times were observed for all the NOMs, which demonstrated the effects of aging on availability of PAHs. Furthermore, the f rd was not only positively correlated with the atomic O/C ratio of NOMs, which represent the geological maturity of NOMs, but also varied with the property of sorbates. We conclude that aging effects of HOCs on NOMs should be a case-specific process and the desorption reversibility depends on the structure and characteristics of both NOMs and sorbates.

show abstract

Section: Possible Mechanisms Contributing To Desorption Resistancementioning

confidence: 99%

Aging effects on sorption–desorption behaviors of PAHs in different natural organic matters

Wang

Chen

et al. 2012

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

show abstract

“…In many spectra of litter, organic layers and light fractions, the main CH 2 peak has two components; those at 30 and 33 ppm, respectively, being associated with more mobile and more rigid fractions (Kögel-Knabner et al 1992;Lee et al 1998;Hu et al 2000). With increasing humification and binding to mineral matter, the more mobile component decreases relative to the rigid fraction.…”

Section: Dd and Dd-toss Spectramentioning

confidence: 99%

“…The purpose is not to repeat what is available elsewhere, such as reviews of applications, noted previously, or basic theory and factors affecting quantitative reliability of NMR spectra (Preston et al 1984;Axelson 1985;Wilson 1987Wilson , 1991Fründ et al 1994a, b;Kinchesh et al 1995;Conte et al 1997a, b;Veeman 1997;Oades 1999, 2000a, b;Hu et al 2000;Mao et al 2000). The second purpose is to raise awareness of the need to develop NMR infrastructure and expertise in SOM studies in a variety of contexts.…”

mentioning

confidence: 99%

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Preston¹

2001

Can. J. Soil. Sci.

112

104

View full text Add to dashboard Cite

).Preston, C. M. 2001. Carbon-13 solid-state NMR of soil organic matter -using the technique effectively. Can. J. Soil Sci. 81: 255-270. Solid-state 13 C CPMAS NMR offers many options for characterizing carbon in soil organic matter (SOM). Its effectiveness, however, is often limited by a poor understanding of the techniques, and lack of hands-on access and training opportunities for students. Of nearly 250 modern NMR systems in Canada, approximately one is genuinely available for SOM studies, and there is poor communication between NMR operators and SOM users. While quantitative reliability can be addressed to some extent by multiple contact-time experiments or single-pulse (Bloch decay) spectra, it is also important to consider the effects of spectrometer background, spinning sidebands (especially with higher magnetic fields) and processing operations such as linebroadening, phasing and baseline correction. In many studies, more consideration needs to be given to instrument specifications, the type of information needed, and whether sample fractionation or pretreatment should be used. Structural information can be greatly enhanced by dipolar-dephasing and sideband suppression sequences. Sequences based on relaxation differences can reveal pools of carbon with different structures. Data analysis can be enhanced by principal component analysis, spectrum deconvolution and difference spectra. Studies of xenobiotics and C metabolism can be greatly aided by 13 C-labeling. However, a key limitation to SOM applications remains the gap in culture and expectations of the users.Key words: Soil organic matter, 13 C CPMAS NMR, Bloch decay, dipolar dephasing, spinning sidebands Preston, C. M. 2001. Analyse de la matière organique du sol par RMN au 13 C électronique -de l'importance de bien utiliser la technique. Can. J. Soil Sci. 81: 255-270. La RMN CPMAS 13 C électronique permet de caractériser le carbone présent dans la matière organique du sol (MOS) de diverses manières. Il arrive souvent cependant que cette technique perde de son efficacité parce qu'on la connaît mal et parce que les étudiants n'ont pas eu la chance de l'examiner ou de l'expérimenter. Sur les 250 systèmes modernes de RMN existant au Canada, un seul, à peu près, est vraiment réservé à l'étude de la MOS; de plus, la communication passe mal entre les opérateurs de systèmes RMN et les utilisateurs de MOS. Bien qu'on puisse remédier dans une certaine mesure au problème de la fiabilité quantitative en multipliant les expériences sur la durée de contact ou en recourant au spectre obtenu après une seule impulsion (décroissance de Bloch), il ne faut pas négliger les effets de l'arrière-plan du spectromètre, de la rotation des bandes latérales (surtout quand le champ magnétique est puissant) et des opérations de traitement comme l'élargissement des lignes, la mise en phase et la correction de la ligne de base. Dans de nombreux cas, on devrait accorder plus d'attention aux paramètres de l'instrument, au genre de données requises et à la nécessité de fractionner et...

show abstract

“…These properties have been attributed to long alkyl side chains. Tombacz and Hu et al recently found considerable polymethylene-(CH 2 ) characteristic peaks in the 13 C NMR spectra (22,23). One of the problems interpreting spectroscopic studies of the aliphatic character of soil HAs is the different nomenclature.…”

Section: A Ar Ro Om Ma At Ti Ic C a An Nd D A Al Li Ip Ph Ha At Ti Icmentioning

confidence: 99%

Peer Reviewed: Investigating Humic Acids in Soils

Steelink¹

2002

Anal. Chem.

View full text Add to dashboard Cite

Poly(methylene) Crystallites in Humic Substances Detected by Nuclear Magnetic Resonance

Cited by 191 publications

References 31 publications

Aging effects on sorption–desorption behaviors of PAHs in different natural organic matters

Aging effects on sorption–desorption behaviors of PAHs in different natural organic matters

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Peer Reviewed: Investigating Humic Acids in Soils

Contact Info

Product

Resources

About