Fulvic acid terrestrial

Stuermer and Payne (1976) compared the H and C NMR spectra of a Sargasso seawater fulvic acid to terrestrial fulvic acids. The proton spectrum of the Sargasso Sea fulvic acid that they isolated by adsorption on XAD-2 resin had broad bands in the following regions (their assignment of the protons is shown in parentheses) 1.0-1.7 ppm (aliphatic protons), 1.7-2.5 ppm (protons on carbon atoms adjacent to functional groups such as carbonyl groups), and 7.3-7.9 ppm (aromatic protons). The positions of these bands were measured relative to tetramethylsilane (TMS) as 0. The relative areas of these bands were 15 10 1. Stuermer and Payne (1976) pointed out that... 

Humic acids (HA) and fulvic acids (FA) are the main components of humic substances (HS), which are the most chemically and biochemically active and widely spread fractions of nonliving natural organic matter in all terrestrial and aquatic environments. They comprise a chemically and physically heterogeneous group of substances with colloidal, polydis-persed, polyelectrolyte characteristics and mixed aliphatic and aromatic nature (Senesi and Loffredo 1999). 

NOM is common in sediments, soils, and near ambient (<50 °C) water. The materials result from the partial decomposition of organisms. They contain a wide variety of organic compounds, including carboxylic acids, carbohydrates, phenols, amino acids, and humic substances (Drever, 1997, 107-119 Wang and Mulligan, 2006, 202). Humic substances are especially important in interacting with arsenic. They result from the partial microbial decomposition of aquatic and terrestrial plants. The major components of humic substances are humin, humic acids, and fulvic acids. By definition, humin is insoluble in water. While fulvic acids are water-soluble under all pH conditions, humic acids are only soluble in water at pH >2 (Drever, 1997, 113-114). 

We found consistent differences in the fluorescence properties of fulvic acids from streams where fulvic acids are terrestrially derived and from lakes where fulvic acids are microbially derived (McKnight et al., 2001). The upper maximum in microbially derived samples is more sharply defined and... 

In the Front Range of the Rocky Mountains, the N enrichment of alpine catchments from increased atmospheric N deposition from agricultural and urban development on the plains is an important environmental and resource issue (Williams et al., 1996). The difference in N content (about 0.5-1.0% for terrestrially derived DOM vs. about 2-3% for microbially derived DOM) could be significant in terms of estimating the contribution of dissolved fulvic acid flux to the yield of N from alpine and subalpine catchments in the Rocky Mountains. The example for this alpine catchment illustrates the potential usefulness of the fluorescence index in field studies addressing applied issues related to environmental management. 

Only 0.05% (about 4X1019 g) of the Earth s carbon is not locked up in sedimentary rocks and only about 9% of that is organic.538 The organic carbon is divided roughly among seawater (45%), soil (40%), and terrestrial plants (15%). Humic substances are traditionally considered to comprise three main fractions humic acids that are soluble in alkali, but insoluble in acid fulvic acids soluble both in alkali and in acid and humin insoluble both in alkali and in acid. 

Relative to soil humic substances, humic substances from Lake Celyn, Wales, and fulvic acids from lakes near Mt. St. Helens contain larger amounts of reactive acidic functional groups (especially carboxyl groups). The reason for this is not known. In Lake Celyn, 24% of the humic acid carbon is carboxyl and 40% is aromatic, suggesting that the Lake Celyn humic acids are largely of terrestrial origin (M. A. Wilson et al., 1981a). 

The ratios of humic to fulvic acids in estuarine and coastal sediments range from 0.4 to 3.4, the higher values being associated with areas or sediments having a terrestrial influence (Palacas et al., 1968 Brown et al., 1972 Hue and Durand, 1973 Pelet and Debyser, 1977 MacFarlane, 1978). These values are also consistent with those from other marine and terrestrial environments (Ishiwatari, 1966 Kononova, 1975 Stuermer et al., 1978 Cronin and Morris, 1982). Other parameters measured on coastal humic substances, such as elemental composition, spectral properties, organic components, stable isotope ratios, or C ages (Pelet and Debyser, 1977 Stuermer et al., 1978 Benoit et al., 1979 Nissenbaum, 1979) are consistent with terrestrial or marine humic compounds, or a mixture of these two endmembers. 

FIGURE 8. Pyrolysis-gas chromatography of fulvic acids, humic acids, and stable residues from marine sediments containing terrestrial organic input (Mahakam Delta) and planktonic organic input (Black Sea). 

Humic and fulvic acids are presumed to arise by two classical natural processes. Terrestrial humates are found in the following pathway plants soil humates peat — coal. Aquatic humates start with soil leachates or marine phytoplankton and go through a sequence sediments kerogen petroleum. There are conditions which mix the two processes as well. As a result, there are a host of names and symbols applied to these compounds, such as peat humic acid, coal fulvic acid, soil humic acid, and so on. Depending on their oxidation state, they may be heavily bound to metal ions. Within each class of humic acid, there are subclassifications, such as Podzol Bj, humic acid, lignite fulvic acid. Other types are classified by geological age, depth in a sediment, and type of aquatic environment. The following discussion will attempt to relate elemental composition to these broad classes of humates. 

Aquatic humic substances may be found in groundwater, river water, lakes, marshes, bogs, swamps, and seawater. The source of the humates may be autochthonous or allochthonous that is, the humates may be formed from phytoplankton in the water or they may be leached into the aquatic environment from terrestrial plants, leaf litter, soil, or subsurface deposits. Relatively undisturbed marine environments have humic and fulvic acids formed almost entirely from native phytoplankton inland surface waters contain major contributions from allochthonous sources. Mixing of the two types of materials may occur, as in the estuaries of rivers. 

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. ... 

Dempsey, B. A. and O Melia, C. R. (1983). Proton and calcium complexation of four fulvic acid fractions. In Aquatic and Terrestrial Humic Materials (R. F. Christman and E. T. Gjessing, eds.). Ann Arbor Science, Ann Arbor, MI, pp. 239-273. 

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