In soil humic substances

Stumm W, Morgan JJ (1995) Aquatic chemistry, 3rd edn. WUey, New York Sutton R, Sposito G (2005) Molecular structure in soil humic substances The new view. Environ Sci Technol 39 9009-9015... 

Xia, K., Bleam, W., and Flelmke, P. A. (1997a). Studies of the nature of and Pb binding sites in soil humic substances using X-ray absorption spectroscopy. Geochim. Cosmochim. Acta 61, 2211-21. 

Sutton, R., and Sposito, G. (2005). Molecular structure in soil humic substances the new view. Environ. Sci. Technol. 39, 9009-9014. 

Freeze-dried DOM samples collected with the siphon-elution system (Kuzyakov and Siniakina, 2001) for the first time showed diurnal dynamics in the molecular-chemical composition of maize rhizodeposits (Kuzyakov et al., 2003). In a forthcoming study with maize, Melnitchouck et al. (2005) showed that amino acids, especially aspartic acid, asparagine, glutamic acid, phenylalanine, leucine and isoleucine contributed to the more intensive rhizodeposition during daytime than during nighttime. Furthermore, the maximum of thermal volatilization of peptides at low pyrolysis temperature in Figure 14.8 indicates the rhizodeposition or microbial formation of free amino acids rather than amino acids bound in peptides or trapped in soil humic substances. 

The occurrence of a predominantly aliphatic humin in marine sediments has been known for some time (Stadnikov, 1930 Breger, 1960 Cane, 1976 Stuermer et al., 1978). This humin was believed to be the precursor of aquatic kerogen in ancient shales and as such has been extensively studied. However, the discovery that a structurally similar aliphatic component exists in humin from peats and even soils is a major new finding that has demonstrated the usefulness of solid-state C NMR. The analytical visibility of this component in soil humic substances has been masked by the over-... 

Xia K, Skyllberg UL, Bleam WF, Bloom PR, Nater EA, Helmke PA (1999) X-ray absorption spectroscopic evidence for the complexation of Hg(II) by reduced sulfur in soil humic substances. Environ Sci Technol 33 257-261... 

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