Showing papers on "Humic acid published in 1980"

Effect of pH and uranium concentration on interaction of uranium(VI) and uranium(IV) with organic ligands in aqueous solutions

Abstract: The effect of pH and uranium concentration on the interactions of uranium(VI) and uranium(IV) with organic ligands was studied by employing dialysis and ultrafiltration techniques. The interactions of U(VI) and U(IV) with organic ligands in nitrate or chloride aqueous solution have been found to be pH-dependent. The stability constants of uranium-organic complexes decrease in the order: fulvic acid>humic acid>tannic acid for U(VI) and humic acid>tannic acid>fulvic acid for U(IV). Scatchard plots for the uranium-organic acid systems indicate two types of binding sites with a difference in stability constants of about 10/sup 2/. Ultrafiltration of uranium-humic acid complexes indicates that U(VI) and U(IV) ions are concentrated in larger molecular size fractions (>5.1 nm) at pH less than or equal to 3 and in smaller molecular size fractions (in the range 5.1 to 3.1 nm and 2.4 to 1.9 nm) at pH greater than or equal to 5. 7 figures, 4 tables.

Biodegradation and Stabilization after 2 Years of Specific Crop, Lignin, and Polysaccharide Carbons in Soils

Abstract: The purpose of this study was to follow the biodegradation and stabilization in two soils of specific carbons of model and cornstalk lignins, lignin monomer alcohols, wheat straw, and the polysaccharide fraction of wheat straw over a 2-year incubation period using C-labeled substrates. Incubations were carried out in a closed, constantly aerated system and the CO2 released determined at specific intervals. After incubation the amounts of residual C in various soil humus fractions, in the biomass, and that solubilized by acid hydrolysis were determined. During the 2-year period, about 40% of the ring and two-side chain carbons of coniferyl and coumaryl alcohol units in model and cornstalk lignins had evolved as CO2. Losses of CH2OH and three-side chain and of OCH3 carbons varied from 52 to 69%. The degradation rate was most rapid during the first 3 to 6 months of incubation. Total C losses from whole wheat straw and cornstalks for comparison at 2 years were about 72% and for the polysaccharide portion of the wheat straw, 83%. During the first 6 months about 47% of the twoside chain and ring carbons and 61 to 66% of the other carbons of free coniferyl alcohols had evolved as CO2. During the next 18 months these values had increased only about 11%. A major portion of the residual lignin carbons was recovered in the HA fractions, relatively small quantities were lost upon 6M HCl hydrolysis, and < 1% was estimated to be in the biomass. Most of the residual wheat straw C and especially the polysaccharide carbon was solubilized upon 6M HC1 hydrolysis, 3 to 8% was still present in biomass, and 50% remained in the NaOH extracted soil. The results indicate that the major portions of the lignin carbons are incorporated into the more resistant or aromatic portions of the soil humus. The polysaccharide carbons, on the other hand, are metabolized and utilized for energy and synthesis of cell polymers, primarily proteins and polysaccharides, some of which are stabilized in the humus but are still susceptible to acid hydrolysis. Loss as CO2 and distribution of the residual carbons of free lignin alcohols in HA and losses upon 6M HC1 hydrolysis were intermediate between the lignin and polysaccharide carbons. Additional Index Words: lignin C2 incorporation in biomass; lignin C, incorporation in humic acid; lignin alcohols, biodegradation of View complete article To view this complete article, insert Disc 4 then click button8

Phenolic ethers in the organic polymer of the Murchison meteorite

Abstract: Seven phenolic acids and many nonphenolic organic acids, including large amounts of meta-hydroxy (3-hydroxy) benzoic acid and 3-hydroxy-1,5-benzene-dicarboxylic acid, were obtained from the organic polymer of the Murchison C2 chondrite upon oxidation with alkaline cupric oxide. The phenolic acids apparently were derived from phenolic ethers in the polymer, which in turn probably were formed from carbon monoxide and hydrogen by catalytic Fischer-Tropsch type reactions in the solar nebula. In contrast, terrestrial polymers such as lignin, humic acid, and coal yield mainly para-hydroxy (4-hydroxy) benzene derivatives by the same oxidation procedure.

Fluorescence excitation spectra of humic substances

Abstract: Fluorescence excitation spectra of fulvic acid (FA) and humic acid (HA) were recorded at different pH as well as at different netural salt concentrations. Spectra of both FA and HA exhibited distin...

Microbial degradation and stabilization of 14C-labeled lignins, phenols, and phenolic polymers in relation to soil humus formation.

Abstract: Humus is a natural product of the soil environment which is formed during the biological degradation of plant residues. Although the humus generally constitutes less than 1 to about 10% of the soil mass, it is a very important fraction. Simple phenolic substances in soil can be derived from degradation of plant phenolic polymers, such as lignin, and through microbial synthesis. Use of specifically 14C-labeled phenols, lignins, fungal melanins, and model humic acid polymers makes it possible to determine which of the constituent carbons of polymers are utilized most readily by the soil organisms and which are relatively more important in soil humus formation. The lignins of corn stalks were labeled by injecting specifically 14C-labeled ferulic or p-coumaric acids as lignin precursors into the stalks of growing plants and extraction of the ground stalks after harvest with hot ethanol to remove low-molecular- weight, labeled compounds.

Eolian particulates from oceanic and rural areas—their lipids fulvic and humic acids and residual carbon

Abstract: The lipids of eolian particulates from oceanic areas (primarily the Atlantic) consist of predominantly terrestrial higher plant waxes and microbial lipid residues of mainly a lacustrine origin. Their solvent-insoluble organic matter has been separated into fulvic acid, humic acid and residual carbon fractions. The humic acids exhibit properties typical of terrestrial soil humates. The residual carbon consists primarily of amorphous carbon (soot). The lipids of rural particulate samples consist primarily of higher plant wax (based on the distributions of the n-alkanes, n-fatty acids and n-alcohols), with lesser amounts of higher plant terpenes and of microbial lipid residues from various sources. Some minor anthropogenic pollutants are also present. These samples were collected during summer and winter in the western United States. These data indicate that primary biogenic residues (i.e. plant waxes and terpenes, etc.) are major components of eolian particulates in the troposphere away from urban areas. This natural background of eolian organic matter is a significant component in the global cycling and flux of carbon.

Effects of heavy metals in combination with NTA, humic acid, and suspended sediment on natural phytoplankton photosynthesis.

Abstract: The tested heavy metal concentrations: Cd, Cu≥5·10−8M, Zn, Pb≥5·10−7M, Hg≥5·10−9M, and a mixture with the concentrations of each metal ten times more dilute, had inhibitory effects on the photosynthesis of phytoplankton from Lake Tyrifjorden. A moderate increase in the water's turbidity or colour reduced the biological availability of the metals and thus their effect on the photosynthetic rate. The increase in anthropogeneous metal load which has taken place in most watercourses may thus be counteracted by the natural influence of dissolved organic matter and by processes in lakes and rivers causing increased turbidity. NTA led to detoxification of Cd, Zn, Pb, and Cu while Hg and the metal mixture became more toxic. An increase in NTA concentration may be the result if this substance comes into use as a substitute for phosphorus in detergents. In Lake Tyrifjorden this may have some unwanted implications since the sediments in the deeper part of the lake are severely contaminated by mercury (HONGVE and SKOGHEIM unpubl.), and NTA may release this as an NTA-Hg complex to the water (CHAU and SHIOMI 1972). NTA complexations of mercury adsorbed to the sediment may thus give a new and quantitatively important contribution to the internal cycle of mercury in the lake. It will also give directly, without microbiological methylation, a substance which may affect the plankton photosynthesis at a concentration which is only a little higher than the present concentration of mercury in the water.

Towards a direct, non‐destructive method of characterising soil humic substances using 13c n.m.r.

Abstract: Summary The structure of a humic acid from a New Zealand pasture topsoil has been investigated by conventional solution 13C n.m.r. spectroscopy and by the cross polarisation technique. Relaxation results showed that a pulse spacing of about 0.2 s was optimum for n.m.r. of the humic acid dissolved in 0.5 M aqueous NaOH. Aromatic rings accounted for 26 per cent of the total carbon. Cross polarisation n.m.r. is a viable method for obtaining 13C spectra of solid humic acids, although aromaticity cannot be estimated as accurately as for coals.

The effect of pH on the retention of Cu, Pb, Zu and Cd by clay-humic acid mixtures

Abstract: The amount of metal ion sorbed by the solids increased with increasing pH over the range 3 to 6, and with mixtures of clay-cellulose or illite-humic acid the uptake corresponded to the direct addition of individual substrate adsorption values. When the humic acid samples were admixed with Na+-form kaolinite or montmorillonite, there was some reduction in adsorption, attributable to component interactions, and this effect was most marked in the presence of Cu and Zn ions.

Humus fraction ratios as a means of discriminating between horizon types

Abstract: Humus fraction distribution in a wide range of horizon samples was examined by measuring carbon content in humic acid (Ch), in fulvic acid (Cf) and in the strongly colored polyphenolic component of the fulvic acid fraction (Ca). Fraction distribution was described by the ratios Ch/Cf and Ca/Cf. It was concluded that humus fraction ratios were related to horizon types as used in the Canadian System of Soil Classification, and were effective in discriminating between certain horizon types, particularly between Luvisolic Bt and Podzolic Bf. The results also suggested that humus fraction ratios may be effective in separating distinct sub-populations within Ah horizons and Bf horizons in general, based on qualitative differences in organic matter present. Aspects of the role of humus fractions in soil genesis are discussed.

Effect of Low pH on the Chemical Structure and Reactions of Humic Substances

Abstract: Humic substances are probably the most widely distributed organic carbon-containing compounds on the earth’s surface, occurring in soils, fresh waters and in the sea After many years of stagnation, interest in humic substances has been increasing in recent years Soil and water scientists, geochemists, environmentalists, biologists and chemists have come to realize that humic substances participate in, and often control, many of the reactions that take place in soils and waters Also, the relatively recent commercial availability of such sophisticated and powerful analytical instruments as the gas chromatographic-mass spectrometric-computer system and advanced Nuclear Magnetic Resonance and Electron Spin Resonance Spectrometers have made possible significant advances in our knowledge of the chemical structure and reactions of humic substances

Humid acid influence on the growth and copper tolerance of chlorella sp.

Abstract: The authors describe and discuss experiments carried out withChlorella sp. in which the effect of humic acid on its growth was studied. Also the coupled effect of humic acid and tolerance to cupric ions was demonstrated. Some ecological implication are discussed.

Method of producing humic acid

Abstract: A liquid humic acid concentrate and a process for making the same is disclosed in which the humic acid is formed by mixing a humic acid bearing ore in a quantity of water and caustic soda for a specified period of time and continuing to mix to form a liquid product of humic acid.

Determining the role of human substances in the fate of pesticides in the environment.

Abstract: The data presented in this paper emphasize that the behavior and fate of pesticides in the environment is influenced by humic substances. Various methods most frequently used for the characterization of humic substances are discussed. Both humic acid and fulvic acid can solubilize in water certain organic compounds and are important carriers of some pesticides in soil. Humic substances have the potential for promoting the nonbiological degradation of many pesticides. Several methods of bleaching humus color from drinking water, including chlorination, ozonation, and UV-radiation, are described. Finally, the photochemical stability to UV-radiation of certain pesticides in aqueous fulvic acid solution is discussed.

Effect of humic acids on the activity of two peroxidases

Abstract: The activity of two peroxidases-from horseradish roots and Streptococcus faecalis-is inhibited by synthetic and natural humic acids Kinetic analyses revealed that inhibition of the horseradish enzyme is due to binding of the donor substrate guaiacol to humic acids Peroxidase from Streptococcus faecalis is inhibited by competitive interactions between the donor substrate NADH and humic acids for the enzyme Binding of H2O2 to any of the enzymes was not influenced The rate of inhibition by synthetic and natural humic acids was different; hydroquinone humic acid and an acetylated derivative were considerably more effective than humic acids from white peat Der Einflus von Huminsauren auf die Aktivitat zweier Peroxidasen Die Aktivitat zweier Peroxidasen-aus Meerrettichwurzeln und Streptococcus faecalis-wird durch synthetische und naturliche Huminsauren herabgesetzt Kinetische Analysen ergaben fur das Meerrettichenzym, das die Hemmung auf eine Bindung zwischen dem Donorsubstrat Guaiacol und den Huminsauren zuruckzufuhren ist Fur das Bakterienenzym konnte gezeigt werden, das die Huminsauren als mit dem Donorsubstrat NADH konkurrierende Inhibitoren auftreten, also kompetitiv wirken Die Bindung des H2O2 wurde bei keinem der beiden Enzyme beeinflust Die Hemmwirkung von synthetischen und naturlichen Huminsauren erwies sich als unterschiedlich; die Hemmung durch Hydrochinon-Huminsaure und deren acetylierter Form war erheblich ausgepragter als durch Huminsaure aus Weistorf

Soil Dating by Fractional Extraction of Humic Acid

Abstract: . The addition of organic materials derived from the upper soil layer yields, for samples at greater depth, younger 14C dates than the date of deposition. To find a criterion for the contamination with younger carbon in a soil sample, we examined the radiocarbon concentrations in two humic acid fractions and humin taken from the same sample. The humic acid extracted from a soil sample was divided into two fractions HA1 and HA2. HA1 is the first fraction extracted by 30 minutes' heating with 2 percent NaOH solution, and HA2 is the second fraction extracted by 2 hours' heating with 2 percent NaOH solution after the extraction of HAI. The residue was assumed as the humin (HM). Many of the peat or soil samples taken from the layer just above the nonpermeable layer contain appreciable amounts of organic materials transported from the upper layer after the sedimentation of the deposits. For the limited number of cases tested here, there is a trend in which the contaminants are selectively extracted by HAl or HA2. When the soil samples are contaminated the ages of the HA1 and HA2 fractions appeared to differ widely in most cases. Agreement between the HAI, HA2, and HM ages may be used as a criterion for the reliability of the soil dating.

Distribution of oxygen-containing functional groups and elements in humic acids from marine sediments

Abstract: The elemental composition and oxygen-containing functional groups contents in the marine humic acids from the five sediment samples from Sagami Bay and Suruga Bay were determined. Kumada's method of classification of soil humic acids was applied to the marine humic acids. The carbon, nitrogen, hydrogen, oxygen and sulfur contents of the marine humic acids were, on average, 52.96, 5.12, 5.79, 34.99 and 1.13%, respectively, without wide variation. In comparison with terrestrial humic acids, the marine ones had relatively lower carbon content and higher hydrogen and nitrogen contents. It is suggested that the marine humic acids have more aliphatic and less aromatic character, as expected from their possible origins, e.g., phytoplankton. The total acidity, carboxyl, phenolic and alcoholic hydroxyl, carbonyl and methoxyl group contents in the marine humic acids were, on average, 5.80, 3.27, 2.53, 2.53, 3.09 and 0.41 milliequivalents per gram of dry ash-free humic acid (me g−1), respectively. From quantitative data on the elemental composition and functional groups of the average marine humic acid, its empirical formula was calculated to be C107H138O20(COOH)9(OH)7 phenolic (OH)7 alcoholic (CO)9(OCH)3N10S. The marine humic acids were similar to the so-called B type of soil humic acids with regard to the distribution of functional groups and spectroscopic properties.

Organocation speciation. I. A comparison of the interactions of methylene blue and paraquat with bentonite and humic acid

Abstract: A model System composed of bentonite, humic acid (HA), polystyrene sulphonic acid (PSSA), methylene blue (MB), and paraquat was used to characterize the possible interactions of organocations in natural waters. The adsorption and desorption studies with bentonite indicated that the clay had a strong preference for the organocations over alkali and alkaline earth cations. Paraquat saturated the bentonite up to the cation exchange capacity whereas methylene blue did not completely saturate the clay but did form methylene blue aggregates on the clay surface. The aggregates could be readily removed by washing with distilled water. The organocation interactions with the anionic polyelectrolytes were more susceptible to changes in pH or ionic strength. Paraquat could be completely desorbed from HA and PSSA by raising the solution ionic strength to 0.1. Methylene blue could not be completely removed from the humic acid but could be removed from PSSA by raising the ionic strength to 0.1. The studies indicate that...

Characteristics of the green fraction of P type humic acid

Abstract: P type humic acid which has absorption bands near 615, 570, and 450 run due to the presence of dihydroxyperylenequinone (DHPQ) was investigated by gel-chromatography. Humic acid samples were fractionated using Sephadex G-50 as gel material and 0.1 n NaOH, with or without 1.5 m urea, as eluent. The absorption spectra of the effluent fractions were measured, and elution curves were drawn on the basis of the optical density at 600 nm. In general, the intensity of the absorption bands due to DHPQ increased with increasing fraction number, accompanied by a change in effluent color from brown, greenish brown to green. Based on the elution curves, the effluent fractions of a humic acid containing a large amount of the green fraction were divided into six groups: B1, B2, BG, G1, G2, and G3. These fraction groups, especially the G groups and cercosporin, a dihydroxyperylenequinone pig ment, were compared by absorption spectroscopy, ultrafiltration, ultimate analysis, TLC, and gel-chromatography. The green...