Gudrun Abbt-Braun

Structural characterization of aquatic humic substances: The need for a multiple method approach

Abstract.An overview of different characterization methods and the possibilities for describing structural elements of humic substances from aqueous environments (HS, or refractory organic substances (ROS)) is given within this review. The application of different analytical methods for the qualitative and quantitative characterization of HS, including physical/chemical analysis (elemental analysis, acid/base titration), spectroscopic methods (UV/VIS, NMR, fluorescence, mass spectrometry), fractionation methods (gel chromatography, flow-field-flow-fractionation), and degradation methods (oxidation, pyrolysis, hydrolysis) are discussed. The paper focuses on the most commonly used chemical, spectroscopic and chromatographic methods used in the last few years. Aspects concerning information related to newer procedures are considered. Case studies representing results gained from reference samples isolated from brown water and wastewater effluents are given to cross-check results gained from several methods. The influence of different isolation procedures on the specific character of the fractions is also discussed.

Refractory organic substances in the environment

Preface. List of Authors. List of Abbreviations. Setting the Scene. The Relevance of Reference Materials Isolation and General Characterization. Element Determination and its Quality Control in Fractions of Refractory Organic Substances and the Corresponding Original Water Samples. Structural Investigations. Heavy Metal and Halogen Interactions with Fractions of Refractory Organic Substances Separated by Size exclusion Chromatography. Characterization of Refractory Organic Substances and Their Metal Species by Combined Analytical Procedures. Application of Nuclear Magnetic Resonance Spectroscopy to Structural Investigations of Refractory Organic Substances Principles and Definitions. Structural Characterization of Refractory Organic Substances by Solid state High resolution 13C and 15N Nuclear Magnetic Resonance. Quantification of Substructures of Refractory Organic Substances by Means of Nuclear Magnetic Resonance. Nuclear Magnetic Resonance Spectroscopy Investigations of Silylated Refractory Organic Substances. Isotopic Evidence for the Origin and Formation of Refractory Organic Substances. Analytical Pyrolysis of Humic Substances and Dissolved Organic Matter in Water. Charaacterization of Refractory Organic Substances by HPLC/MS. UV Visible Spectroscopy and the Potential of Fluroscent Probes. Stationary and Time resolved Fluorescence for Refractory Organic Substances Characterization. Structural Characterization of Refractory Organic Substances by Pyrolysis GC/FTIR. X ray Microscopy Studies of Refractory Organic Substances. Fractionation of Refractory Organic Substances by Electrophoresis. Occurence of Amino Acids, Carbohydrates, and Low molecular weight Organic Acids in Refractory Organic Substances. Serological Characteization of Refractory Organic Substances. Biochemical and Biological Characterization. Formation, Utilization and Transformation of Some Refractory Organic Substances by Aquatic Microorganisms. Effect of Microorganisms on the Formation and Transformation of Iodine Species of Refractory Organic Substances. The Influence of Refractory Organic Substances on Bacterial Colonization and Diversity Patterns. Influence of Refractory Organic Substances on Enzyme Activity in vivo and DNA Damage of Aquatic Microorganisms. Effects of Dissolved Organic Matter on the Bioconcentration of Organic Contaminants and on Reproduction in Aquatic Invertebrates. Molecular Interactions. Sorption of Dissolved Organic Matter on Soil Particles and its Dependence on their Surface charge Properties. Dissolved Organic Carbon in Seepage Water Production and Transformation During Soil Passage. Refractory Organic Substances in Aggregated Forest Soils Retention versus Translocation. Refractory Organic Substances Derived from Organic Amendments in Soil Formation, Translocation, and Interaction with Xenobiotics. Analysis of the Binding Amitrole and Anilazine to Aquatic and Terrestrial Refractory Organic Substances. Sorption and Chemical Reactions of Polycyclic Aromatic Hydrocarbons with Dissolved Refractory Organic Substances and Related Model Polymers. Investigation of the Interactions between Polycyclic Aromatic Compounds and Refractory Organic Substances with Stationary and Time resolved Fluorescence and Absorption Spectroscopy. Index. Author Index.

Basic characterization of reference NOM from Central Europe: Similarities and differences

Abstract The FA and HA fractions represent 20 to 50% of the DOC of the original samples, depending on the origin, and serve as reference materials. The original aqueous samples and the aqueous solutions of the reference materials were characterized with methods suited for measuring samples at natural concentrations. The DOC normalized values of the spectral absorbances (λ = 254 nm; λ = 436 nm) in the original water samples were highest for the brown water and brown coal water and lowest for the secondary effluents. The FA fractions were similar in the UV-absorbance with the exception of the low-absorbing groundwater FA, reflecting a low density of double bonds. The DOC-normalized proton capacity of the FA fractions (10 to 20 μmol/mg) was highest for the brown coal, brown water, and soil-derived samples and again lowest for the groundwater FA. The high values are due to a higher contribution of the weak acids of phenolic type. Specific data for copper complexation capacity (0.5 to 2.5 μmol/mg) went parallel to the proton capacity. The characterization of the FAs by gel chromatography with organic carbon detection revealed three major fractions. The refractory part at short retention time dominated in the brown water and soil-derived samples, whereas the fractions for the lower molecular mass acids at long retention times were dominant in the secondary effluent and the brown coal isolate. Comparison with UV-detected chromatograms revealed a strong decrease in the specific absorbance of the secondary effluent. Up to 3% of the total mass of the FAs could be identified as hydrolyzable amino acids with the highest yield in the sample from secondary effluent and the lowest one in the groundwater sample. The nitrogen content was always higher in the FAs compared to the HAs of the same origin. The application of gel chromatography fluorescence and fluorescence decay time distribution analysis turned out to be a useful tool to differentiate between the different fractions of NOM, the isolates obtained by different methods (e.g., XAD-8, membrane separation) and the fractions of the samples from different origin and age. This is of special value, for the information can also be obtained for samples with natural NOM concentrations, even though further investigations required for full understanding of the data. This work is part of a multi-disciplinary research program (ROSIG: Refraktare Organische Sauren in Gewassern), funded by the German Research Association (DFG).

Basic characterization of Norwegian NOM samples — Similarities and differences

Abstract NOM (natural organic matter) samples, isolated by reverse osmosis (RO), and nine NOM samples, concentrated by low-pressure, low-temperature evaporation (EVA) from various origin in Norway, were characterized by different methods. The methods included elemental content of the freeze-dried samples (C, H, N, and O), elemental content of the redissolved samples (DOC, Na, Ca, Cu, Fe, and Mn), specific spectral absorbance at λ = 254 nm (A(254 nm)/DOC) and at λ = 436 nm (A(436 nm)/DOC), UV/Vis-spectra, specific fluorescence (excitation and emission spectra), proton capacity, Cu-complexation capacity, and content of hydrolysable amino acids and carbohydrates. In addition, chromatographic characterization by gel chromatography and reversed-phase chromatography was done. Studies on adsorption and flocculation abilities and the formation of trihalomethanes (THM) and organic halogens adsorbable on activated carbon (AOX) upon chlorination were also investigated. Comparison of the results showed that the samples were different according to the origin of the sample, isolation procedure, and time of sampling. The differences are not the same for all parameters used. Standardized procedures have to be applied to redissolve the organic material in water in order to compare data. For the samples investigated, it was shown that parameters like elemental analysis (H/C ratio), the specific spectral absorption in the UV range, proton capacity, complexation capacity and anionic particle charge, amount of hydrolysable amino acids and carbohydrates, adsorption behaviour on activated carbon, and the THM-FP are sensitive parameters to show differences concerning origin and isolation procedure.

Structural investigations of aquatic humic substances by pyrolysis-field ionization mass spectrometry and pyrolysis-gas chromatography/mass spectrometry

Abstract The present state-of-the-art in structural investigations of aquatic humic substances and their fractions such as fulvic and humic acids by pyrolysis-field ionization mass spectrometry is outlined. An integrated approach to interpretation uses complementary data of elemental analysis, functional group determinations, Cu 2+ -complexation, H + -capacity and results from u.v.-vis- and FT-i.r.-spectroscopy. Proposed building blocks of the molecular structure are supported by chromatographic investigations using Curie-point Py-GC/MS and the available literature reports. The potential and limitation of the applied methodology are discussed.

Humic-like substances from landfill leachates — Characterization and comparison with terrestrial and aquatic humic substances

Abstract XAD-isolated fractions of organic acids from landfill leachates and those from soil and bog lake water show similarities: yellow-brown color, acidic functionality of several μmol/mg DOC and high molecular weight. The humic-like substances isolated from the seepage water of the dumping areas, however, have higher carbon-, hydrogen- and sulphur-content, lower quantities of phenolic groups, lower complexation capacities for copper and lower molecular weight. Organic acids from anaerobic seepage water seem to represent an early stage in the genesis of humic substances.

Challenges of an integrated water resource management for the Distrito Federal, Western Central Brazil: climate, land-use and water resources

Land-use/cover change (LUCC) and climate change are major controlling factors for water resources in the Distrito Federal in Western Central Brazil. Dynamic LUCC in the region has severe impacts on water resources, while climate changes during the last three decades is thought to have only moderate effects. LUCC affects water quantity mostly during base flow conditions. River basins with substantial expansion of agriculture since the end 1970s show a dramatic decrease of base flow discharge by 40–70%, presumably due to irrigation. In contrast, the effects of urbanization on runoff are less distinct, since factors controlling runoff generation might be more variable. For water quality, we found urban areas to have a strong influence on the parameters CSB, NH4+, and suspended solids. In addition, we assume emerging pollutants, e.g. organic (micro)pollutants, might play a major role in the future. The project IWAS-ÁGUA DF focuses on creating the scientific base to face these problems in frame of an IWRM concept for the region. Results of our study will be a contribution to an IRWM concept for the Distrito Federal and will help to maintain high standards in water supply for the region.

Fluorescence Decay of Natural Organic Matter (NOM)—Influence of Fractionation, Oxidation, and Metal Ion Complexation

Time-resolved fluorescence measurements of aquatic natural organic matter (NOM) derived from different origins were performed using the time-correlated single-photon counting technique. The obtained experimental data were analyzed with nonlinear least-squares (NLLS) algorithms. The results of a global analysis with three exponential decay terms were compared with the results obtained in a distribution analysis (exponential series method; ESM). Fulvic acid fractions from a bog lake water, from a brown coal production effluent, and from a soil seepage water as well as NOM from a municipal waste water were investigated. The influence of the emission wavelength on the NOM fluorescence decay was monitored. Furthermore, the influence of fractionation using size exclusion chromatography, of ozonation, and of metal ion complexation on the fluorescence decay of the NOM samples was investigated.

Removal of hydrophilic pollutants from water with organic adsorption polymers: Part I. Adsorption behaviour of selected model compounds☆

Abstract The adsorbability of 2-aminonaphthalene-1-sulfonate, diuron, 1-naphthol and natural organic matter (NOM) onto an organic polymer resin and onto activated carbon was investigated. Isotherms with the substances alone and in the presence of dissolved NOM were measured. There was a good adsorbability of diuron and 1-naphthol on both sorbents. At low initial concentrations of the compounds the activated carbon showed higher adsorptivity, whereas for high initial concentrations the polymer resin showed an equal or better adsorption behaviour. 2-Aminonaphthalene-1-sulfonate and the NOM showed favorable adsorption behaviour to activated carbon but was only poorly adsorbed on the polymer resin. In the presence of NOM, the adsorbability of the single compounds decreased significantly on activated carbon. Nearly no influence was found for the adsorption of the pollutants on the resin. For the polymer resin, additionally, the breakthrough behaviour of the substances was investigated. The results obtained in the batch experiments for the single substances were confirmed. However, in the presence of NOM the breakthrough occurred at shorter times for all three substances. Regeneration of the resin with isopropanol proved to be a good cleaning method. A recovery of 92–96% of the substances was reached.

Adsorbed and bound residues in fulvic acid fractions of a contaminated groundwater : Isolation, chromatographic and spectroscopic characterization

Humic substances (HS) were isolated from two contaminated groundwater samples (B22 and B53) from a site of a former gas facility. The isolation yielded almost only the fulvic acid fractions (FA). For characterization spectroscopic (UV, fluorescence) and chromatographic techniques (hydrophobic interaction chromatography – HIC as well as size-exclusion chromatography – SEC) were applied. The sample designated B22 FA was collected from the contamination plume whereas the sample B53 FA was collected downstream. Distinct differences were exhibited by these samples. The UV and fluorescence spectra as well as the HIC and SEC chromatograms of the B53 FA sample resemble those of the FA fraction obtained from natural water (groundwater, bog). The HIC and SEC chromatograms reveal the presence of organic compounds in B22 FA which can be derived from coal tar contaminants or their metabolites. Some of the compounds can be extracted from the FA fraction with non-polar organic solvents indicating adsorptive forces between the contaminants and the FA fraction. Adsorbierte und gebundene Ruckstande in den Fulvinsaurefraktionen eines kontaminierten Grundwassers – Isolierung:, chromatographische und spektroskopische Charakterisierung Von den zwei kontaminierten Grundwasserproben B22 und B53 eines ehemaligen Gaswerksgelandes wurden Huminstoffe (HS) isoliert. Dabei wurde jeweils vorwiegend die Fulvinsaurefraktion (FA) erhalten. Zur Charakterisierung der FA-Fraktionen wurden spektroskopische (UV, Fluoreszenz) und chromatographische Methoden (hydrophobe Wechselwirkungschromatographie HIC auf Umkehrphasen und Grosenausschluschromatographie SEC) angewandt. Die Proben zeigen deutliche Unterschiede, wobei B22 FA direkt aus der Schadstoffahne und B53 FA aus dem Abstrombereich stammt. Berucksichtigt man die UV- und Fluoreszenzspektren sowie die Chromatogramme der HIC- und SEC-Trennung, so ist B53 FA sehr gut mit FA-Fraktionen naturlicher Gewasser (Grund- bzw. Braunwasser) vergleichbar. Die Anwesenheit von organischen Verbindungen in der Probe B22 FA wird besonders in den Chromatogrammen nach HIC- und SEC-Trennung deutlich. Diese Verbindungen konnen auf Kohleteerruckstande oder deren Metaboliten zuruckgefuhrt werden. Ein Teil der organischen Verbindungen last sich mit unpolaren organischen Losemitteln aus der FA-Fraktion extrahieren, was auf Sorptionswechselwirkungen zwischen den Kontaminanten und der FA-Fraktion hinweist.