Use of 13C NMR and FTIR for elucidation of degradation pathways during senescence and litter decomposition of Aspen leaves
No abstract available.
Book chapter↗
Geology topics
J.A. Leenheer
Publications and source records attributed to J.A. Leenheer.
Models of metal binding structures in fulvic acid from the Suwannee River, Georgia
Fulvic acid, isolated from the Suwannee River, Georgia, was assessed for its ability to bind Ca2+, Cd2+, Cu2+, Ni2+, and Zn2+ ions at pH 6 before and after extensive fractionation that was designed to reveal the nature of metal binding functional groups. The binding constant for Ca2+ ion had the greatest increase of all the ions in a metal binding fraction that was selected for intensive characterization for the purpose of building quantitative average model structures. The 'metal binding' fraction was characterized by quantitative 13C NMR, 1H NMR, and FT-1R spectrometry and elemental, titrimetric, and molecular weight determinations. The characterization data revealed that carboxyl groups were clustered in short- chain aliphatic dibasic acid structures. The Ca2+ binding data suggested that ether-substituted oxysuccinic acid structures are good models for the metal binding sites at pH 6. Structural models were derived based upon oxidation and photolytic rearrangements of cutin, lignin, and tannin precursors. These structural models rich in substituted dibasic acid structures revealed polydentate binding sites with the potential for both inner-sphere and outer-sphere type binding. The majority of the fulvic acid molecule was involved with metal binding rather than a small substructural unit.Fulvic acid, isolated from the Suwannee River, Georgia, was assessed for its ability to bind Ca2+, Cd2+, Cu2+, Ni2+, and Zn2+ ions at pH 6 before and after extensive fractionation that was designed to reveal the nature of metal binding functional groups. The binding constant for Ca2+ ion had the greatest increase of all the ions in a metal binding fraction that was selected for intensive characterization for the purpose of building quantitative average model structures. The `metal binding' fraction was characterized by quantitative 13C NMR, 1H NMR, and FT-IR spectrometry and elemental, titrimetric, and molecular weight determinations. The characterization data revealed that carboxyl groups were clustered in short-chain aliphatic dibasic acid structures. The Ca2+ binding data suggested that ether-substituted oxysuccinic acid structures are good models for the metal binding sites at pH 6. Structural models were derived based upon oxidation and photolytic rearrangements of cutin, lignin, and tannin precursors. These structural models rich in substituted dibasic acid structures revealed polydentate binding sites with the potential for both inner-sphere and outer-sphere type binding. The majority of the fulvic acid molecule was involved with metal binding rather than a small substructural unit.
Georiga↗
Aqueous infrared carboxylate absorbances: Aliphatic di-acids
Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA − species is linearly related to the microscopic acidity constantof the H 2 A species, with σ p K <0.25 log units; this relationship falls on the same line as previously observed for mono-carboxylic acids. The linear relationship applies to the acidity constant of the HA − species only when the two acid groups are well separated (>2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate `intrinsic' p K a values of carboxylic acids, in addition to providing quantitative estimates of ionization.
Spectrochimica Acta - Part A: Molecular and Biomol↗
Use of 13C NMR and ftir for elucidation of degradation pathways during natural litter decomposition and composting I. early stage leaf degradation
Oxidative degradation of plant tissue leads to the formation of natural dissolved organic carbon (DOC) and humus. Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectrometry have been used to elucidate the chemical reactions of the early stages of degradation that give rise to DOC derived from litter and compost. The results of this study indicate that oxidation of the lignin components of plant tissue follows the sequence of O-demethylation, and hydroxylation followed by ring-fission, chain-shortening, and oxidative removal of substituents. Oxidative ring-fission leads to the formation of carboxylic acid groups on the cleaved ends of the rings and, in the process, transforms phenolic groups into aliphatic alcoholic groups. The carbohydrate components are broken down into aliphatic hydroxy acids and aliphatic alcohols.
Soil Science↗
Mechanism of formation of humus coatings on mineral surfaces 1. Evidence for multidentate binding of organic acids from compost leachate on alumina
Measurements of the infrared linear dichroism of carboxylate groups of organic acids from compost leachate adsorbed to an alumina surface and the enthalpy of adsorption of this reaction have been made. The linear dichroism measurements indicated that the carboxylate groups are not free to rotate. This limited rotation probably results from bidentate binding of the carboxylate groups. The molar enthalpy of adsorption of the acids is approximately −100 kJ mol −1 . This high value for enthalpy of adsorption may best be explained by assuming that two or more carboxylate groups on a single dissolved organic carbon (DOC) molecule coordinate to the surficial aluminium ions.
Colloids and Surfaces A: Physicochemical and Engin↗
Data on natural organic substances in dissolved, colloidal, suspended-silt and -clay, and bed-sediment phases in the Mississippi River and some of its tributaries, 1987-90
The Mississippi River and some of its tributaries were sampled for natural organic substances dissolved in water and in suspended and bed sediments during seven sampling cruises from 1987-90. The sampling cruises were made during different seasons, in the free-flowing reaches of the river from St. Louis, Missouri, to New Orleans, Louisiana. The first three cruises were made during low-water conditions, and the last four cruises during high-water conditions. The purpose for sampling and characterizing natural organic substances in the various phases in the river was to provide an understanding of how these substances facilitate contaminant transport and transformations in the Mississippi River. Significant conclusions of this study were: (1) Natural organic substances appear to stabilize ' certain colloids against aggregation; therefore, these colloids remain in suspension and can act as transport agents that are not affected by sedimentation. Bacteria were found to be a significant fraction of organic colloids. (2) A new class of organic contaminants (polyethylene glycols) derived from nonionic surfactant residues was discovered dissolved with natural organic substances in water. These polyethylene glycols have the potential to affect both organic and inorganic contaminant transport in water. (3) The entire dissolved organic-matter component under varying hydrologic and seasonal conditions was characterized. (4) A method was developed to characterize organic matter in sediment by solid-state, 13C-nuclear magnetic resonance spectrometry. (5) The organic matter in suspended sediments was characterized by a variety of spectral and nonspectral methods. The protein component (significant in trace-metal binding) and lipid component (significant in organic-contaminant binding) were found to be major constituents in natural organic matter in suspended sediment. (6) Pools are reservoirs acting as traps of sedimentary organic matter of allochthonous origin and export material of autochthonous nitrogen. (7) A major portion of the mass of organic colloids in transport consisted of bacterial cells.
Mississippi River↗
Humic substances in the Suwannee River, Georgia: Interactions, properties, and proposed structures
No abstract available.
Georgia↗
Identification of persisten anionic surfactant-derived chemicals in sewage effluent and groundwater
Preparative isolation and fractionation procedures coupled with spectrometric analyses were used to identify surfactant-derived contaminants in sewage effluent and sewage-contaminated groundwater from a site located on Cape Cod, Massachusetts. Anionic surfactants and their biodegradation intermediates were isolated from field samples by ion exchange and fractionated by solvent extraction and adsorption chromatography. Fractions were analyzed by 13C nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry. Carboxylated residues of alkylphenol polyethoxylate surfactants were detected in sewage effluent and contaminated groundwater. Linear alkylbenzenesulfonates (LAS) were identified in sewage effluent and groundwater. Groundwater LAS composition suggested preferential removal of select isomers and homologs due to processes of biodegradation and partitioning. Tetralin and indane sulfonates (DATS), alicyclic analogs of LAS, were also identified in field samples. Although DATS are a minor portion of LAS formulations, equivalent concentrations of LAS and DATS in groundwater suggested persistence of alicyclic contaminant structures over those of linear structure. Sulfophenyl-carboxylated (SPC) LAS biodegradation intermediates were determined in sewage effluent and groundwater. Homolog distributions suggested that SPC containing 3-10 alkyl-chain carbons persist during infiltration and groundwater transport. Surfactant-derived residues detected in well F300-50 groundwater have a minimum residence time in the range of 2.7-4.6 yr. LAS detected in groundwater at 500 m from infiltration has been stable over an estimated 50-500 half lives.
Conference Paper↗
Presence and potential significance of aromatic-ketone groups in aquatic humic substances
Aquatic humic- and fulvic-acid standards of the International Humic Substances Society were characterized, with emphasis on carbonyl-group nature and content, by carbon-13 nuclear-magnetic-resonance spectroscopy, proton nuclear-magnetic-resonance spectroscopy, and infrared spectroscopy. After comparing spectral results of underivatized humic and fulvic acids with spectral results of chemically modified derivatives, that allow improved observation of the carbonyl group, the data clearly indicated that aromatic ketone groups comprised the majority of the carbonyl-group content. About one ketone group per monocyclic aromatic ring was determined for both humic and fulvic acids. Aromatic-ketone groups were hypothesized to form by photolytic rearrangements and oxidation of phenolic ester and hydrocarbon precursors; these groups have potential significance regarding haloform formation in water, reactivity resulting from active hydrogen of the methyl and methylene adjacent to the ketone groups, and formation of hemiketal and lactol structures. Aromatic-ketone groups also may be the point of attachment between aliphatic and aromatic moieties of aquatic humic-substance structure.
Georgia↗
A filtration and column-adsorption system for onsite concentration and fractionation of organic substances from large volumes of water
A portable filtration and column-adsorption system which can concentrate suspended sediment and dissolved-aqueous organic substances onsite was developed. Organic solutes also are fractionated into hydrophobic- and hydrophilic-acid, base, and neutral fractions. Subsequent isolation of organic solutes from fraction concentrates and extraction of organic constituents in suspended sediment entrained on filter tubes is performed by a variety of procedures in the laboratory. Three surface-water samples and one ground-water sample ranging in volume from 300 to 1,100 liters were processed through the filtration and column-adsorption system, yielding from about 0.8 to 3.0 grams of recovered organic carbon per sample.
Water Supply Paper↗
Physical, chemical, and biological aspects of subsurface organic waste injection near Wilmington, North Carolina
Explore the source record for details and available documents.
Open-File Report↗
Physical, chemical, and biological aspects of subsurface organic waste injection near Wilmington, North Carolina
From May 1968 to December 1972, an industrial organic waste was injected at rates of 100 to 200 gallons per minute (6.3 to 12.6 litres per second) into a sand, gravel, and limestone aquifer of Late Cretaceous age by Hercules Inc. located near Wilmington, North Carolina. This report presents both field and laboratory data pertaining to the physical, chemical, and biological effects of waste injection into the subsurface at this particular site, a case history of the operation, predictions of the reactions between certain organic wastes and the aquifer components, and descriptions of the effects of these reactions on the subsurface movement of the wastes. The case history documents a situation in which subsurface waste injection could not be considered a successful means of waste disposal. The first injection well was used only for 1 year due to excessive wellhead pressure build-up above the specified pressure limit of 150 pounds per square inch (10.3 bars). A second injection well drilled as a replacement operated for only 5 months before it too began to have problems with plugging. Upward leakage of waste into shallower aquifers was also detected at several wells in the injection-observation well system. The multiple problems of plugging, high pressures, and waste leakage suggested that the reactive nature of the waste with the aquifer into which it was injected was the primary reason for the difficulties experienced with waste injection. A site study was initiated in June 1971 to investigate waste-aquifer interactions. The first stage of the study determined the hydrogeologic conditions at the site, and characterized the industrial waste and the native ground water found in the injection zone and other aquifers. The injection zone consisted of multiple permeable zones ranging in depth from about 850 to 1,000 feet (259 to 305 metres) below land surface. In addition to the injection zone, aquifers were found near depths of 60, 300, 500, and 700 feet (18, 91, 152, and 213 metres) below land surface. The aquifers from 300 feet (91 metres) down to the injection zone were flowing artesian with the natural pressure of the injection zone being 65 feet (20 metres) above land surface at the site. The dissolved solids concentration in the native ground water increased with depth to an average value of 20,800 mg/l (milligram per litre) (two-thirds that of seawater) in the water from the injection zone. Sodium chloride was the major dissolved solid, and all of the ground water below 300-feet (91-metres) depth was slightly alkaline. Dissolved organic carbon of the industrial waste averaged 7,100 mg/l and 95 percent of the organic carbon was identified and quantified. The major organic waste constituents in order of decreasing abundance were acetic acid, formic acid, p-toluic acid, formaldehyde, methanol, terephthalic acid, phthalic acid, and benzoic acid. Prior to injection, the waste was neutralized with lime to pH 4 so that the major inorganic waste constituent was calcium at a concentration of 1,300 mg/l. The second stage of the site study involved the observation of waste-aquifer interactions at various wells as the waste arrived and passed by the wells. Water samples obtained from three observation wells located 1,500 to 2,000 feet (457 to 607 metres) from the original injection well gave evidence for biochemical waste transformations at low waste concentrations. Gas that effervesced from these water samples contained up to 54 percent methane by volume. Ferrous iron concentrations as high as 35 mg/l, hydrogen sulfide gas, and sulfide precipitates were additional indicators of biochemical reductive processes in the subsurface environment. Approximately 3,000 organisms per millilitre were found in uncontaminated ground water from the injection zone whereas in waste-contaminated wells, the number increased to levels as high as 1,000,000 organisms per millilitre. High concentrations of waste were found to be toxic to microo
Professional Paper↗
Classification of organic solutes in water by using macroreticular resins
A series of macroreticular resin adsorbents was evaluated for ability to extract and fractionate organic solutes found in natural waters. Studies with organic solute standards and natural water samples lead to the development of dissolved organic carbon (DOC) fractionation analysis whereby the DOC is concentrated and fractionated by macroreticular resins into acid, base, and neutral hydrophobic organic solute fractions and into acid, base, and neutral hydrophilic organic solute fractions. The hydrophobic solutes were sorbed and fractionated on nonionic, nonpolar macroreticular resins, and the hydrophilic solutes were sorbed and fractionated by macroreticular ion-exchange resins. Organic-inorganic complexes as well as organic solutes were isolated by resin sorption. DOC fractionation analysis was developed to serve as a compound classification that fills the gap in organic solute characterization between the organic solute concentration (DOC) and specific compound identification.
Journal of Research of the U.S. Geological Survey↗