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Humic material/substances

Humic materials substances consist of a heterogeneous mixture of compounds for which no single structural formula will suffice. In fact, extracted humic materials are different from place to place. Therefore, no unique exact value could be represented the molecular weight of the extracted humics. Some researcher (Stevenson F.J., 1982) proposed that the molecular weight of humics are ranged from 2000 (fulvic acids) to 300000 (humins). Based on this point, a medium value of 150000 was used as the molecular weight in our quenching calculation. [Pg.57]

According to Hatcher and co-authors47 the CP/MAS NMR technique opens up new means of distinguishing between various structural features of aquatic and ter-restric humic materials of rather old origin. They found, for instance that the aliphatic carbons of the humic substances in Holocene sediments, are dominant components suggesting an input of lipid-like materials. [Pg.17]

The amphiphilic nature of dissolved humic substances (DHS) lends them the ability to associate with both hydrophobic organics and polar or ionic species [62-64]. Inorganic ions or mineral colloids in solution will interact with the electrically active surface of humic material in solution or in the solid phase according to the same bonding forces which lead to the association between SP0M and the solid mineral matrix. Humic matter in water is associated with... [Pg.123]

If released to water, 1,3-DNB and 1,3,5-TNB may be subject to direct photolysis when exposed to sunlight because both compounds can absorb light at wavelengths greater than 290 nm (ERA 1976 Mill and Mabey 1985). However, no data were located regarding the photolysis of 1,3,5-TNB in water. The photolytic half-life of 1,3-DNB in pure water was calculated to be 23 days (Simmons and Zepp 1986). A three-to four-fold increase in the rate of photoreaction of 1,3-DNB was observed in ambient waters containing natural humic substances or in distilled water containing dissolved humic materials compared to reaction without humic substances (Simmons and Zepp 1986). This enhancement of the reaction rate has been attributed to catalysis of the photoreaction by photosensitization effects of humic substances. [Pg.82]

An extraction method for isolating humic substances from water by using XAD-8 has been proposed by Thurman and Malcolm (9) (see box). Humic substances in natural waters represent almost the entire hydrophobic acid fraction. This method has been used to isolate 4.25 g of humic substances from 24,500 L of ground water from the Fox-hills-Laramie aquifer and to obtain 500 g of humic material from 10,400 L of the Suwannee River (Table II). The sample from the Suwannee River was collected as a reference sample of aquatic humic substances by the International Humic Substances Society. In both of the examples cited, a fc cutoff of 100 was used. [Pg.299]

Hatcher, P. G., Breger, I. A., Dennis, L. W., and Maciel, G. E. (1983). Solid-state 13C-NMR of sedimentary humic substances New revelations on their chemical compostion. In Aquatic and Terrestrial Humic Materials, Christman, R. F., and Gjessing, E. T., eds., Ann Arbor Science, Ann Harbor, MI, pp. 37-81. [Pg.34]

A beneficial effect of humic substances on the nutrient uptake and contents of plants has been reported for the major inorganic elements, such as nitrogen, phosphorus, potassium (Mylonas and McCants, 1980), and sulfur (Guminski, 1968). In addition, the uptake and contents of nutrients such as calcium, magnesium (Mylonas and McCants, 1980), sodium (Vaughan and McDonald, 1976) and copper (Rauthan and Schnitzer, 1981) are also enhanced by humic substances. Most of these reports on the effects of HS on the nutrient contents of plants are purely descriptive, and little attempt has been made to elucidate the mechanisms of the action of the humic material. The authors proposed both an indirect and a direct effect of HS on plant nutrition. In the former case HS may, for example, chelate a cation, thus changing... [Pg.311]

DOM in effluents of a wastewater treatment plant consist of fairly hydrophilic organic material. It is refractory in character and has been classified as humic-like substances (Frimmel et al., 2005). It is obvious from the data given in Table 10.5 (see... [Pg.389]

Weber, J. W. (1988). Binding and transport of metals by humic materials. In Humic Substances and Their Role in the Environment, Frimmel, F. H., and Christman, R. F., eds., John Wiley Sons, Chichester, pp. 165-178. [Pg.405]


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See also in sourсe #XX -- [ Pg.127 , Pg.132 , Pg.134 , Pg.134 ]




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Humic material/substances aqueous

Humic material/substances chlorination

Humic material/substances formation

Humic material/substances marine

Humic material/substances metal chelation

Humic material/substances pollutant associations

Humic material/substances precipitation

Humic material/substances soil/terrestrial

Humic materials

Humic substances

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