Humic-like substance

Measure SAC254 as indicator of the sum of aromatic compounds or SAC436 for humic-like substances. 

Hayes, M. H. B., Dawson, J. E., Mortensen, J. L., Clapp, C. E., and Hausler, M. J. (1985). Comparisons of synthetic humic-like substances with soil humic acids. In Volunteered Papers, 2nd International Conference, International Humic Substances Society (Birmingham, 1984), Hayes, M. H. B., and Swift, R. S., eds., IHSS, University of Minnesota, St. Paul, pp. 

Figure 2.15. FTIR spectra of the humic-like substances produced by (1) C. maxima, (2) C. maxima + C. hirsutus, and (3) C. hirsutus. Reprinted from Yavmetidinov, I. S., Stepnova, E. V., Gavrilova, V. R, et al. (2003). Isolation and characterization of humin-like substances produced by wood-degrading white rot fungi. Appl. Biochem. Microbiol. 39, 257-264, with permission from Springer.

Arafaioli, R, Pantani, O. L., Bosetto, M., and Ristori, G. G. (1999). Influence of clay minerals and exchangeable cations on the formation of humic-like substances (melanoidins) from D-glucose and L-tyrosine. Clay Miner. 34,487-497. 

Senesi, N., Miano, T. M., and Brunetti, G. (1996). Humic-like substances in organic amendments and effects on native soil humic substances. In Humic Substances in Terrestrial Ecosystems, Piccolo, A., ed., Elsevier, New York, pp. 531-593. 

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... 

HULIS humic-like substances, macromolecular organic substances in atmospheric aerosols. 

Biopolymers, Polycyclic Aromatics, Humic-Like Substances, Oxygenated Organic Compounds... 

Chan, M. N., and Chan, C. K. (2003). Hygroscopic properties of two model humic-like substances and their mixtures with inorganics of atmospheric importance. Environ. Sci. Technol. 37, 5109-5115. 

Havers, N., Burba, P., Lambert, J., and Klockow, D. (1998). Spectroscopic characterization of humic-like substances in airborne particulate matter. /. Atmos. Chem. 29,45-54. 

Hoffer, A., Kiss, G., Blazso, M., and Gelencser, A. (2004). Chemical characterization of humic-like substances (HULIS) formed from a lignin-type precursor in model cloud water. Geophys. Res. Lett., 31, doi 10.1029/2003GL018962. 

Kiss, G.,Tombacz,E., Varga, B., Alsberg,T., and Persson, L. (2003). Estimation of the average molecular weight of humic-like substances isolated from fine atmospheric aerosol. Atmos. 

Kiss, G.,Tombacz, E., and Hansson, H. C. (2005). Surface tension effects of humic-like substances in the aqueous extract of troposphere fine aerosol. J. Atmos. Chem. 50, 279-294, doi 10.1007/sl0874-005-5079-5. 

CM80nm, respectively) as peaks related to the component type of humic-like substances [1 (excitation at 310-320 nm and emission at 38(M20nm) as a peak related to the component type of marine humic-like substances y (excitation at 270-280 nm and emission at 300-320 nm) as a peak related to the component type of tyrosine-like and/or protein-like 8 (excitation at 270-280nm and emission at 320-350 nm) as a peak related to the component type of tryptophane-like, proteinlike, and/or phenol-like substances. Parlanti et al. (2002) used the p and y peaks as markers to estimate the biological activity in coastal zones and the different stages of the biological production. 

The effect of montmorillonite and kaolin, saturated with calcium, aluminium, or cupric ions, as well as quartz, on humic-like substances formed from glucose-tyrosine was examined by Arfaioli et al.541 All systems promoted their formation, the effectiveness being strictly related to the amount of added cation. Humification appeared to be due more to the cations than to the type of clay mineral. The clayey systems gave more complex (aromatic) substances than the quartz ones. The cations seemed more effective when free, i.e., associated with quartz rather than with the clays. The nature of the cation was also important, cupric being the most active here. In the end, all systems took on a deep dark colour. 

From the preceding discussions, it should be clear that photochemistry within all phases of the atmosphere is a major driver of chemical transformations in relatively short time scales. With increasing knowledge of the ever-widening array of chromophoric compounds emitted and produced in the atmosphere, there is definitely room for much more fundamental research into primary and secondary photochemical reactions of relevance. In particular, the role of humic-like substances in aerosol, cloud and ice phases needs to be studied. 

For smaller particles, the spectrum is close to the one of the reference spectrum of dissolved substances (see Chapter 4). Chemical absorbance induces a shoulder around 225 nm, often associated with the presence of surfactants in wastewater [23], This shoulder is especially marked on UV spectra of fine colloids in raw wastewater. This tends to show the general affinity of soluble compounds for fine particles and confirms that surface phenomena are more important for finer particles than for the larger ones. This behaviour can also be explained by the presence of macromolecules such as humic-like substances. 

The results show that, depending on fractions, several observations can be drawn. The different responses are related to the diffuse absorption response of solids and colloids. The general tendency is that the slope of the spectrum generally decreases as the particle size increases. Spectra corresponding to suspended solids are flat, confirming a mineral nature. Adsorption phenomenon can be seen mainly on fine colloids, and the shape of soluble fractions (artificially denitrified with the deconvolution method see Chapter 2) is related to the probable presence of humic-like substances (see Chapter 6). 

The spectrum of Munich leachate is more concave with no marked accident, and its absorbance decreases rapidly between 200 and 230 nm, due to a more important salinity, especially chloride ion. This spectrum also gives an indication of the composition of the leachate. Indeed, simple organic molecules that result from the initial degradation process absorb at the beginning of the UV wavelength range, and few humic-like substances are present (low shoulder at 270 nm). 

The studied leachates have a pH close to 7.5-8.5. Acidification has been then made by the addition of sulphuric acid until pH 2. Munich and Augsburg leachates show the same behaviour and are globally not affected by the pH change, proving the low concentration of humic-like substances (Fig. 3). 

On the contrary, Grospierres and Saint-Bres leachates are sensitive to pH (Fig. 4). After acidification, the shape of their UV spectra is the same, but the absorbance decreases all along the wavelength range the organic load is lowered, as shown by COD and DOC values before and after acidification (Table 3). In the same way, the shoulder around 270-280 nm is less important after treatment. This phenomenon is supported by the observation of a precipitate after acidification, probably humic-like substances. 

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