Structural Features of Humic Acid of the Coastal Sediment in Ariake Sea Tidelands: Use of Humic Acid as an Environmental Indicator for River Basins and Coastal Regions

Abstract

Humic substances are heterogeneous mixtures of naturally occurring large molecules in soils, waters, and sediments. 1 Among these, humic acid (HA) is an insoluble material with an acidic pH and is soluble in alkaline solutions. Humic compounds are produced primarily by abiotic reactions of relatively small molecules, such as lignins, lipids, and carbohydrates from plant and microbial biopolymers involving direct conversion; these abiotic reactions are then followed by degradation. 2 The Ariake Sea, which is a typical semi-closed bay located at Kyushu Island in Japan, has a maximum tidal range of about 6 m during the spring tide, and has a vast tideland area covered with several living organisms that are unique in Japan. 3 The unique living systems of this area are likely to be influenced by the circulation of organic and biological compounds from a combination of marine algae and other marine microorganisms that are produced and metabolized. Concerning this area, fishery depression caused by environmental pollution has recently become a problem. 4 The HA in coastal sediments is thought to share most of its major characteristics with terrigenous HA. However, if the circulation of seawater and coastal sediments is sufficiently extensive, the HA in coastal regions would be expected to share some characteristics with the HA in the seawater. Differences between seawater HA and terrigenous HA have been identified and discussed in the literature. [5][6][7][8] The differences between the two types of HA, as proposed by such studies, appear to be quite significant. The mixing and interaction of terrigenous HA and the HA in seawater can be observed by the precise analysis of samples in a relatively large tideland field.Humic acid is a ubiquitous compound, and is abundant in soil and in the surface sediment of coastal regions. Thus, the structural characteristics of humic acid provide general information about the environment of the river basin and the coastal region; these characteristics can therefore be used as a general environmental indicator (such as pollution, civilization effects, and the bacterial activity of a particular region). However, the structural complexity of HA as well as the nature of the mixture of macromolecular compounds in HA and the low solubility of the material served as factors hindering structural investigations of HA for the purpose of larger environmental studies.The present study was intended to be used the HA in the tideland as a record of the present environment and further, an environmental indicator of this region (the tideland and coastal region) of the world generally. For this purpose, the humic acid was extracted from the estuary of a river emptying into the Ariake Sea; the structural features of HA in the tideland were then analyzed. ExperimentalSamples were collected on 6 August 2001 (HY0108) and 23 February 2002 (HY0202) from the coastal region (about 2 m from land) of the Hayatsuegawa-river heading toward Ariake Sea (33˚ 09′41″ N, 130˚ 19′58″ E). The surface sediment (0 -40 cm) w...

Humic Substances and Crude Oil Induce Cytochrome P450 1A Expression in the Amazonian Fish Species Colossoma macropomum (Tambaqui)

“…The NOM sample contained only one resolvable peak that appeared to be from the plastic container in which the material had been held. Analysis of AHA revealed principally aliphatic and partially oxidized compounds, in line with prior chemical analyses of AHA and of other humics (38), but most were not identified by GC-MS. There was a detectable amount of retene (7-isopropyl-1-methylphenanthrene) in the AHA.…”

Complement‐fixing activity of fulvic acid from Shilajit and other natural sources

“…Spectra of all Shilajit fractions and the parent Shilajit sample showed a broad proton resonance between 3.3 and 4.2 ppm, with a maximum near 3.6-3.7 ppm. Resonances in this region derive from protons belonging to methyl and methylene groups connected to electronegative atoms, primarily oxygen, which are present in carbohydrates, methoxy compounds, carboxylic acids, and organic amines (Sciacovelli et al, 1977;Wilson et al, 1983;Grasso et al, 1990;Yamauchi et al, 2004). The signals in the region of 4.0-5.5 ppm are partially due to protons on alcoholic OH groups.…”

Isolation, Characterization and Antifungal Behavior of Humic Acid and Fulvic Acid Fractions from Biowaste Derived Vermiproducts

“…8 conclude that the materials were well crystallized with sharp diffraction peaks at 2θ values 32 θ, 45 θ which are assigned to corresponding planes. There were some slight differences in the sorts of crystals observed in all sample may be due to physicochemical factors (Arroyo et al, 2004;Yamauchi et al, 2004).…”