Humic oxygen content

FIGURE 14. Oxygen-containing functional groups in fulvic acids, humic acids, coal, and lignite as related to carbon and oxygen contents. From Stevenson and Butler (1969) as modified from Blom et al. (1957). 

Humic substances in peatlands are often hypothesized to be precursors in the formation of coal. In Table 2 the elemental analyses of several Canadian peats are compared with those of different coals. The data on peats show that the carbon, sulfur, and nitrogen contents increase with increasing degree of decomposition and the oxygen content decreases. The sulfur con-... 

Use of aqueous solutions of sodium hydroxide for the extraction of humic substances was first described by Achard (1786). Such solutions have been the solvents of choice by most workers since that time. Comparison of elemental analysis data (Table 5) for the 2.5M EDA- and for sodium hydroxide-extracted humic substances show that the carbon and nitrogen contents of the EDA-soluble substances were significantly higher than for those extracted with sodium hydroxide. The reverse was true for the oxygen contents of these substances. 

ATOMIC RATIOS OF CARBON, HYDROGEN, NITROGEN, AND OXYGEN CONTENT AS A GUIDE TO HUMIC SUBSTANCES IDENTIFICATION... 

Saito and Hayano (1981) have also interpreted the presence of a band between 3.3 and 4.6 ppm to indicate that there are polysaccharide ether structures in some of their samples. They found that this band was stronger in fulvic acids from marine sediments than the corresponding humic acids. The marine sediment fulvic acids were higher in oxygen than marine sediment humic acids. Aldrich humic, which is presumably terrestrial in origin, has a still lower oxygen content but does not have a band in this region. These data led Saito and Hayano to conclude that their marine sediment fulvic acids have a polysaccharide character. ... 

Major elements in humic and fulvic acids are oxygen and carbon. The carbon content of fulvic acid ranges from 41 to 51% as compared to 54-59% for humic acid. In contrast, the oxygen content of fulvic acids is higher (40-50%) compared to 33-38% for humic acids (Table 5.9). These data demonstrate that distinct differences exist between fulvic and humic acids. 

Compare and contrast humic and fulvic acids. What is the significance of the higher oxygen content of fulvic acids compared to humic acids ... 

Although widely ranging values for carboxyl content in humic substances have been reported, there is a general trend for fulvic acid fractions to have higher concentrations than humic acids. This is consistent with their higher oxygen content and greater water solubility. 

The objectives of the study presented in this paper were to observe and characterize phototransients produced by laser excitation of natural waters and humic substance (HS) solutions. The photosystems were studied on two scales. On the laboratory scale pulsed laser flash photolysis was used to study the time resolved and spectral behavior of the photochemical transients. Studies to Identify and quantify the transients Included adding energy and electron acceptors and model compounds to the solution and varying parameters such as pH, metal, and oxygen content. On the field scale laboratory data taken at solar actinic wavelengths Is extrapolated using published solar photon fluxes to predict environmental effects of the phototransients studied In this work. This paper thus contains an overview of many experiments performed over four years (16). 

The dissociation of water coordinated to exchangeable cations of clays results in Brtfnsted acidity. At low moisture content, the Brrfnsted sites may produce extreme acidities at the clay surface-As a result, acid-catalyzed reactions, such as hydrolysis, addition, elimination, and hydrogen exchange, are promoted. Base-catalyzed reactions are inhibited and neutral reactions are not influenced. Metal oxides and primary minerals can promote the oxidative polymerization of some substituted phenols to humic acid-like products, probably through OH radicals formed from the reaction between dissolved oxygen and Fe + sites in silicates. In general, clay minerals promote many of the reactions that also occur in homogenous acid or oxidant solutions. However, rates and selectivity may be different and difficult to predict under environmental conditions. This problem merits further study. 

With increasing age of the coals the carbon content increases, and the oxygen and methoxyl content decreases in the material free of bitumen as well as in the isolated humic acids (29). 

Cornelius Steelink. It is possible that other systems may give rise to the. radical species. However, one of our models for humic acids is a biradical cr oh whose radical character would not be changed on acetylation. Our humic acids change very little in spin content on methyladon. It IsJw would be interesting to form sodium salts from your coals to see if ho the spin content increased. This would be fairly convincing evidence for oxygen radicals. 

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