[sup 13]C-NMR spectra and contact time experiment for Skjervatjern fulvic and humic acids

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Environment International; (United States)

DOI:https://doi.org/10.1016/0160-4120(92)90028-3· OSTI ID:7064448

Malcolm, R L ^[1]

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1. Geological Survey, Denver, CO (United States)

The T[sub CP] and T[sub 1[rho]] time constants for Skjervatjern fulvic and humic acids were determined to be short with T[sub CP] values ranging from 0.14 ms to 0.53 ms and T[sub 1[rho]] values ranging from 3.3 ms to 5.9 ms. T[sub CP] or T[sub 1[rho]] time constants at a contact time of 1 ms are favorable for quantification of [sup 13]C-NMR spectra. Because of the short T[sub CP] values, correction factors for signal intensity for various regions of the [sup 13]C-NMR spectra would be necessary at contact times greater than 1.1 ms or less than 0.9 ms. T[sub CP] and T[sub 1[rho]] values have a limited non-homogeneity within Skjervatjern fulvic and humic acids. A pulse delay or repeat time of 700 ms is more than adequate for quantification of these [sup 13]C-NMR spectra. Paramagnetic effects in these humic substances are precluded due to low inorganic ash contents, low contents of Fe, Mn, and Co, and low organic free-radical contents. The observed T[sub CP] values suggest that all the carbon types in Skjervatjern fulvic and humic acids are fully cross-polarized before significant proton relaxation occurs. The [sup 13]C-NMR spectra for Skjervatjern fulvic acid is similar to most aquatic fulvic acids as it is predominantly aliphatic, low in aromaticity (fa[sub 1] = 24), low in phenolic content, high in carboxyl content, and has no resolution of a methoxyl peak. The [sup 13]C-NMR spectra for Skjervatjern humic acid is also similar to most other aquatic humic acids in that it is also predominantly aliphatic, high in aromaticity (fa[sub 1] = 38), moderate in phenolic content, moderate in carboxyl content, and has a clear resolution of a methoxyl carbon region. 10 refs., 6 figs., 3 tabs.

• OSTI ID: 7064448
• Journal Information: Environment International; (United States), Journal Name: Environment International; (United States) Vol. 18:6; ISSN ENVIDV; ISSN 0160-4120
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ACID RAIN
ATMOSPHERIC PRECIPITATIONS
CHEMICAL ANALYSIS
DATA
ENVIRONMENTAL EFFECTS
EXPERIMENTAL DATA
FULVIC ACIDS
HUMIC ACIDS
INFORMATION
NMR SPECTRA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
RAIN
SPECTRA
SURFACE WATERS