ABSTRACT
As indicated in Chapter 1, the elemental composition of humic matter is a very big issue among scientists, with one group being very critical about the presence of an elemental composition, and the other group proclaiming the existence of an elemental composition characterizing humic matter. A number of scientists in the first group above fail to see the significance of an elemental composition, indicating that extraction procedures may have effected changes in the elemental composition of humic substances. However, Steelink (1985) declares that this issue is not clear yet and needs to be resolved by more detailed research. Except for a generous number of criticisms, no further information of interest is available from this group, and as stated by Ziechmann (1994), elemental composition is a dead issue among these scientists. In contrast, a lot of information has been supplied by the second group. Many of them have analyzed the C, H, O, N, and S contents of humic and fulvic acids extracted from a variety
of soils in tropical and temperate regions. These are considered the major elements in humic matter, and a summary of the data is given as examples in Table 5.1. The lignite samples listed in the table above were from the deposits in North Dakota, and the data for the lignite-humic and fulvic acids are the average figures of data reported by Mathur and Parnham (1985), Steelink (1985), Tan et al. (1991), Lobartini et al. (1992), and from unpublished data of the present author. The elemental composition of aquatic humic and fulvic acids are also the average figures of data supplied by Lobartini et al. (1991), Thurman and Malcolm (1981), and from unpublished data of the present author. The black water samples for extraction of these humic substances are from the Okefenokee swamps, Satilla, Ohopee, and Suwannee rivers in the southeastern United States.
