Showing papers on "Humic acid published in 1989"

Acute toxicity of aluminium to fish eliminated in silicon-rich acid waters

Abstract: AN increased level of aluminium in acidified natural waters is a primary cause of fish death from damage to gill epithelia and loss of osmoregulatory capacity1–4. Aluminium toxicity depends on the species of aluminium present (cationic, neutral or anionic) and hence is affected by pH and the presence of complexing ligands, such as fluoride, and organic material, such as humic acid, which may ameliorate aluminium toxicity5,6. But silicic acid, Si(OH) 4, present in natural waters as a consequence of the weathering of the aluminosilicates of rocks and soil minerals, has a strong and unique affinity for aluminium7, although its influence on toxicity has not been investigated. Here we show that, with an excess of Si over Al and with the formation of hydroxy-aluminosilicate species, the bioavailability of aluminium at pH 5 is reduced and acute toxicity is eliminated. Silicic acid concentration should therefore be considered as a key parameter in toxicity studies and could be important for the treatment of vulnerable waters.

Diagenesis of organic matter in georgia salt marshes

Abstract: Organic matter preserved in sediments of Georgia salt marshes derives from Spartina alterniflora and planktonic and bacterial substances. Sources and diagenesis of sedimentary organic material were studied by means of stable C and N isotopes and gas chromatography of pyrolysates from plants, suspended sediments, and a series of muds (modern to 1400 years old) from St Catherines Island, Georgia. Suspended particulate matter ( > 20 μm) has isotopic compositions (δ 13 C = −18 to −22), which are composed of an average 34–42% plankton carbon and 58–65% higher plant detritus, as determined by isotopic mass balance of the system. The δ 13 C of bulk sediments and humic acids (δ 13 C = −18 to −19) extracted from them remain relatively constant over time. The δ 13 C of acid hydrolysates, however, changed from − 15‰ in surface marsh sediment to a δ 13 C of −19 from sediment sampled at a depth of 125 cm. Higher-plant normal-hydrocarbons are present in muds and in particulate matter from the water column, and δ 13 C in lipids and gas chromatography of pyrolysates of samples reflect this addition. With increasing age, δ 15 N of total sediments and acid hydrolysates increases, and the ratio of odd-to-even hydrocarbons in the pyrolysates decreases. Initially, low density material in sediments consists primarily of plant fragments. With time, this material is decayed and diluted by microbial material, changes that are reflected by more negative δ 13 C of −15 to −17·5, as compared to δ 13 C of −12 for moden Spartina , and the addition of n-alkanes in the range of C 13–19 . The isotopic heterogeneity in surface sediments with carbon as an example, ranged from a δ 13 C of −15 (plant fragments) to −22 (sediment following lipid, humic acid, and plant fragment extraction). Nowhere was the C isotopic composition of total Spartina expressed even though microscopic plant pieces, lignocellulose pyrolysis fragments, and n-alkanes from C 22–27 were detected in suspended particulate matter, total sediments, and humic acids.

Dissolved organic matter interaction with napropamide and four other nonionic pesticides

Abstract: Equilibrium dialysis was used to measure the extent of interaction between dissolved organic matter (DOM) and five nonionic pesticides. The association-dissociation of DOM with the relatively polar, nonionic pesticide napropamide [2-(a-naphthoxy)-N,N-diethylpropionamide], was emphasized in this study. A negative linear correlation was found between the log of the solubility and the log of the association coefficient of these five pesticides with dissolved humic acid derived from peat (peat-DHA) (...)

A Spectroscopic and Chemical Investigation on the De-ashing of a Humin

Abstract: (…) This study investigated the effect of de-ashing with aqueous HCl/HF (1.16 M HCl and 2.88 M HF) on chemical properties and 13 C CPMAS NMR spectra of a humin. With progressive de-ashing, the humin became partly soluble in 0.5 M NaOH, and its ash-free composition approached that of the humic acid fraction. The CPMAS NMR spectra showed increasing improvement in resolution and signal-to-noise ratio. (…)

Sequential photochemical and microbial degradation of organic molecules bound to humic Acid.

Abstract: We studied the effects of photochemical processes on the mineralization by soil microorganisms of [2-14C]glycine bound to soil humic acid. Microbial mineralization of these complexes in the dark increased inversely with the molecular weight of the complex molecules. Sunlight irradiation of glycine-humic acid complexes resulted in loss of absorbance in the UV range and an increase in the amount of 14C-labeled low-molecular-weight photoproducts and the rate and extent of mineralization. More than half of the radioactivity in the low-molecular-weight photoproducts appears to be associated with carboxylic acids. Microbial mineralization of the organic carbon increased with solar flux and was proportional to the loss of A330. Mineralization was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. Only light at wavelengths below 380 nm had an effect on the molecular weight distribution of the products formed from the glycine-humic acid complexes and on the subsequent microbial mineralization. Our results indicate that photochemical processes generate low-molecular-weight, readily biodegradable molecules from high-molecular-weight complexes of glycine with humic acid.

Chemical Properties of Metal-Humic Acid Fractions of a Sewage Sludge-Amended Aridisol

Abstract: Humic acid (HA) was extracted from a Domino soil (Xerollic Calciorthids) cropped with barley (Hordeum vulgare L.) and sorghum [Sorghum bicolor (L.) Moench] in experimental plots that received applications of sewage sludge for 4, 5, 6, or 7 yr at rates of 0,22.5, 45, or 90 Mg ha⁻¹ yr⁻¹. The HA samples were characterized chemically by elemental and functional group analyses, total trace metal content, infrared (IR), and electron spin resonance (ESR) spectroscopy. As compared to the nonamended Domino (Xerollic Paleorthids) soil HA, the highest sludge-amended soil HA was extracted in higher yields and had higher N and S contents, lower C/N molar ratios, higher total acidity and phenolic OH content, lower organic free radical content, and higher relative intensity of the amide I and amide II IR absorption bands. These differences are believed to be caused by the incorporation of components typical of the applied sludge organic fraction into the soil HA, i.e., proteinaceous materials, sulfur-containing compounds, and phenolic components. The HA also exhibited a well-defined selectivity in respect to trace metal adsorption/desorption. Copper, Ni, Zn, Fe, and Cr were adsorbed strongly onto readily available sites, or through exchange with more weakly adsorbed trace metal ions (Mn, V, Ti, and Mo). However, the soil HA tended to reach metal saturation at the highest sludge application rates. The ESR analysis showed the presence of indigenous Cu²⁺, Fe³⁺, and VO²⁺-HA complexes in all HA samples. These complexes had similar chemical and structural properties, and were concluded to represent the speciation of the metals in association with HA. In general, the impact of the organic constituents in fresh sludge on the soil HA appeared to be mitigated somewhat by the continual tendency of soil organic matter to attain equilibrium, whereas the metal-organic portion of the soil HA was significantly affected by sludge application. Contribution from the Dep. of Soil and Environ. Sci., Univ. of California, Riverside.

Complexation of Americium(III) with Humic Acid

Abstract: The complexation of the A m 3 + ion with humic acid has been investigated at different pH (5.0, 5.5, 6.0) in 0.1 M and 1.0 M NaC104 by laser-induced photoacoustic spectroscopy (LPAS), UV spectroscopy and ultrafiltration. Two humic acids are included in the study: one is extracted from lake Bradford in Florida and the other is the commercially available Aldrich humic acid, which are purified and protonated. The loading capacity of the Bradford humic acid for the Am 3 + ion is found to be a function of the pH and ionic strength. In solution with the equivalent concentration ratio of humic acid to Am being larger than one, a tridentate complexation is prevalent. The húmate complexation constants determined by taking account of the loading capacity are shown to be independent of the pH and ionic strength. The different methods have resulted in comparable constants: log β = 6.27 ± 0.04 for Aldrich humic acid and log β = 6.36 + 0.14 for Bradford humic acid.

Interactions of toxic organic chemicals with humic substances.

Abstract: Humic substances (HS) are the most widespread and ubiquitous natural nonliving organic materials occurring in all terrestrial and aquatic environments. HS occur not only as the major fraction of soil organic matter (OM), but also in marine, river and lake waters and sediments, sewage effluents of various nature, peat, coal and lignite. The amount of carbon on the earth occurring as humic substances (60×1011 tons) has been estimated to exceed about 10-fold of that occurring in living organisms (7×1011 tons).

Effect of farmyard manure and its humic fractions on the aggregate stability of a sandy–loam soil

Abstract: The effect of cattle manure and its humic fractions on the aggregate stability of a sandyloam soil has been studied. Cattle manure was extracted with 0.1 m NaOH and the extract was dialysed to obtain a combined fulvic acid + humic acid fraction (FHA). Humic acid (HA) was precipitated from this extract, redissolved in 0.1 m NaOH solution and dialysed. The manure and the organic fractions were added at two rates to a sandy–loam soil and the mixtures incubated for 2 and 17 weeks. Changes in the water‐stable aggregation of the soil were followed. In these tests, the effects on water stability of pre‐wetting with alcohol or benzene were also examined. Addition of manure, by itself, was rather ineffectual, but stability was significantly improved after two weeks of incubation by addition of the organic fractions. FHA was much more effective than HA, particularly in increasing stability after the benzene pretreatment. There were only slight changes in aggregation after 17 weeks as compared with 2 weeks. Copyright © 1989, Wiley Blackwell. All rights reserved

Uptake of mercury from aqueous solution by duckweed: The effects of pH, copper and humic acid

Abstract: Studies indicated that duckweed absorbed mercury in water (e.g. lakes) strongly and that after three days it contained up to 2000 ppm of mercury by weight of duckweed. The uptake of mercury was little affected by acidity at pH 4.0 and pH 5.0. The presence of copper ion suppressed the mercury uptake significantly. The presence of 1.0 mM EDTA in solution also suppressed the mercury uptake significantly. Further 10 mg of humic acid in 400 mL solution suppressed the mercury uptake to some degree, probably by complexing the mercury.

Chemical and biological studies on environmental humic acids II. 1H-nmr and IR spectra of humic acids

Abstract: Forty humic acids from various types of soils were examined by 1H nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The 1H-NMR spectra were characterized by peaks which were attributed to aromatic, lactone, methoxyl, and aliphatic protons a, s, and y to aromatic carbon rings. Andisol humic acid showed high percentages of aromatic protons and low percentages of aliphatic and methoxyl protons. Sediment and Inceptisol humic acids showed low aromatic proton and high aliphatic proton percentages. Based on the relationships between the H/C ratio and various proton percentages, it was found that with the progression of humiflcation, aliphatic side chain and methoxyl groups split off, and condensed aromatic rings were introduced into the humic molecules. The characteristic absorption of lignin appeared in the IR spectra of Entisol, Histosol, and Inceptisol humic acids. Entisol, Oxisol, and sediment humic acids showed a strong absorption arising from peptides. Andisol humic acid showed no evidence o...

Contribution by pigmented fungi to P-type humic acid formation in two forest soils

Abstract: A study of the microfungi in two forest soils containing P-type humic acids was carried out to examine their possible contribution to the accumulation of humic substances in soils. A total of 23 fungal species was identified, but only Acremonium fusidioides, Cladosporium herbarum, Geomyces pannorum, Oidiodendron tenuissimum. Penicillium citrinum, Torulomyces humicola and Trichoderma harzianum synthesized acid-insoluble pigments with possible chemical similarity to soil humic acids. Amongst them, the formation of the green pigment characteristic of P-type humic acids was demonstrated only in C. herbarum. The analytical characteristics of the melanins of C. herbarum and O. tenuissimum suggested that these fungal polymers tend to accumulate in the soil humic fraction, in spite of the abundance of biodegradable materials. Successive oxidative degradation with potassium persulphate followed by alkaline permanganate oxidation of the residue was carried out on the melanin from C. herbarum. It showed that polymers from this fungus yielded similar products to those obtained from humic acids. Among the degradation products, the aliphatic compounds were dominant, mainly consisting of fatty acids with a different pattern to that found in the free lipid fraction, while the aromatic compounds were mainly benzenecarboxylic acids.

Fertilizer and/or soil amendment

Abstract: The present invention relates to a fertilizer and/or soil amendment containing L ascorbic acid, marine algae, and humic acid The fertilizer and/or soil amendment may be produced in a solid form or a liquid form The fertilizer has utility in promoting the growth of grass and plants A method of preparing the fertilizer and/or soil amendment is also described

Characterization of Humic Acid from No‐Tilled and Tilled Soils Using Carbon‐13 Nuclear Magnetic Resonance

Abstract: Chemical composition of humic acids is important due to their reactivity with soil-applied pesticides and fertilizer amendments. Humic acids from continuously (7 yr) no-tilled and tilled cotton, corn, and soybean plots in West Tennessee were characterized by ¹³C-NMR from soils sampled at various depths. Humic acids were extracted with dilute NaOH solution and purified with KOH-KCL and HCL-HF solution, respectively. NMR solution spectra generated on a Jeol FX 90Q spectrometer (Jeol Co., Tokyo, Japan) were divided into six regions (0–40, 40–62, 62–105, 105–150, 150–170, and 170–190 ppm) and peak areas compared. Humic acid composition differed by soil depth and crop. Small differences were observed between tillage systems. Aliphatic and aromatic carbons ranged from 48 to 65% and 25 to 40% of total peak area, respectively. Carboxyl groups of humic acids as determined by ¹³C-NMR ranged from 9 to 13%. Humic acids extracted from those soils containing larger amounts of C (surface no-tilled treatments) had greater aliphatic to aromatic ratios, perhaps due to earlier stages of decomposition.