Organic matter in sediment layers of an acidic mining lake as assessed by lipid analysis. Part II: Neutral lipids.

Natural neutralization of acidic mining lakes is often limited by organic matter. The knowledge of the sources and degradability of organic matter is crucial for understanding alkalinity generation in these lakes. Sediments collected at different depths (surface sediment layer from 0 to 1 cm and deep sediment layer from 4 to 5cm) from an acidic mining lake were studied in order to characterize sedimentary organic matter based on neutral signature markers.

Rapid screening of phytoremediation effluents by off-line tetramethylammonium hydroxide assisted thermochemolysis.

Tetramethylammonium hydroxide-assisted thermochemolysis performed in an off-line mode proved a useful tool in determining organic compounds in the effluent from laboratory-scale phytoremediation systems. Studies were performed with artificial wastewaters contaminated with xylenols and densely rooted Juncus effuses plants. Analytes in these molecular-level based studies included xylenol substrates, an array of stable intermediates such as low molecular weight carboxylic acids and oxidative coupling products (tetramethyl biphenyldiols, tetramethyl diphenylether monools), diagnostic fatty acid biomarkers, as well as lignin-, carbohydrate-, and protein-based phenols and carboxylic acids.

Sorption determination of phenols and polycyclic aromatic hydrocarbons in a multiphase constructed wetland system by solid phase microextraction.

Non-degradative sorption of organic pollutants onto plant roots during phytoremediation is an essential retardation mechanism. To determine the extent of the attenuation processes the freely dissolved concentrations of organic solutes must be determined rather than their total concentrations. Thus, the assessment of attenuation caused by sorption onto plant compartments can be biased when using traditional methods.

Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: fatty acids.

Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5 cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far.

Kinetics of desorption of organic compounds from dissolved organic matter.

This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute-DOM sorption equilibrium and drives the desorption process.

Aromatic intermediate formation during oxidative degradation of Bisphenol A by homogeneous sub-stoichiometric Fenton reaction.

The elimination of Bisphenol A (BPA) from contaminated waters is an urgent challenge. This contribution focuses on BPA degradation by homogeneous Fenton reagent based on reactive ()OH radicals. Pronounced sub-stoichiometric amounts of H(2)O(2) oxidant were used to simulate economically viable processes and operation under not fully controlled conditions, as for example in in situ groundwater remediation.

Pathways of advanced oxidation of phenol by Fenton's reagent--identification of oxidative coupling intermediates by extractive acetylation.

Homogeneous Fenton reaction (H(2)O(2)/Fe(2+) system) using significantly substoichiometric concentrations of H(2)O(2) oxidant to oxidize phenol was characterized focusing on the formation of stable aromatic intermediates. Beyond the most abundant benzenediols, the pattern of aromatic intermediates was chiefly characterized by hydroxylated biphenyls and diphenyl ethers with different degrees of hydroxylation. Hydroxylated dibenzofurans (DBF), p,p'-dioxins, as well as highly condensed aromatic intermediates including polyols of polycyclic aromatic hydrocarbons (PAHs), could also be detected, but in lower concentrations.

Formation of chlorinated biphenyls, diphenyl ethers and benzofurans as a result of Fenton-driven oxidation of 2-chlorophenol.

Homogeneous catalytic Fenton oxidation proved to be very efficient in the degradation of high concentrations (3.9 mM) of 2-chlorophenol (2-CP) in aqueous matrices. When using [H(2)O(2)](0)/[2-CP](0) substoichiometric molar ratios of 4 and 16, the detected aromatic intermediates included mainly chlorinated benzenediols, with the virtual absence of condensation products of higher molecular weight.

Fatty acid patterns of genetically modified Cry3Bb1 expressing Bt-maize MON88017 and its near-isogenic line.

Fatty acid (FA) profiles of the Bt-maize line MON88017 expressing the Cry3Bb1 protein and its near-isogenic line DKC5143 were examined. Plant compartments under study included leaves taken from different internodes and roots. Sample preparation involved pressurized liquid extraction (PLE) of the biomass, transmethylation of the extracted lipids to give fatty acid methyl esters (FAMEs), and finally GC-MS analysis.

Molecular level lignin patterns of genetically modified Bt-maize MON88017 and three conventional varieties using tetramethylammonium hydroxide (TMAH)-induced thermochemolysis.

Bt-maize MON88017, its near-isogenic line DKC5143, and the two conventional varieties DK315 and Benicia were subjected to tetramethylammonium hydroxide (TMAH)-induced thermochemolysis to reveal molecular level lignin patterns. MON88017 is genetically modified to express the Cry3Bb1 protein aimed at the Western corn rootworm Diabrotica virgifera virgifera, a serious threat for European maize production. The results indicated that roots of the Bt-maize were characterized by a slightly enhanced total lignin content (by approximately 7%) compared to the near-isogenic line, whereas the molecular-based patterns, expressed by the relative fractions of p-hydroxyphenyl, guaiacyl, and syringyl breakdown products (P-, G-, and S-units, respectively) were virtually identical for both lines.

Polymerized coumaric acid as a model substrate for terrestrial-derived dissolved organic carbon utilized by aquatic microorganisms.

It is now widely accepted that many surface waters receive more terrestrial carbon than assumed in the past, and that aquatic food webs are largely based on the supply of external dissolved organic carbon. However, very little information is available on how efficiently external carbon is utilized by microorganisms and transported to consumers of higher trophic levels. To address this issue, we prepared and tested polymers of 14C-p-coumaric acid (PCA) as a model substrate for terrestrial organic carbon.

Complexation-flocculation of organic contaminants by the application of oxyhumolite-based humic organic matter.

Control of hazardous organic micropollutants is a challenging water quality issue. Dissolved humic organic matter (DOM) isolated from oxyhumolite coal mined in Bohemia was investigated as a complexation agent to remove polycyclic aromatic hydrocarbons (PAHs) and functionalized phenols from water by a two-stage process involving complexation and flocculation. After the formation of humic-contaminant complexes, ferric salts were added resulting in the precipitation and flocculation of the DOM and the associated pollutants.

Combined application of non-discriminated conventional pyrolysis and tetramethylammonium hydroxide-induced thermochemolysis for the characterization of the molecular structure of humic acid isolated from polluted sediments from the Ravenna Lagoon.

Humic acid (HA) isolated from highly polluted sediment from the Ravenna Lagoon (Italy) was subjected to pyrolysis/tetramethylammonium hydroxide (TMAH)-induced thermochemolysis to reveal the impact of industrial activities on humification. Special effort was made to distinguish between analytes originating from the polymeric humic organic matter network along with sequestered compounds (which cannot be released by solvent extraction), and the solvent-extractable lipid fraction sorbed onto the organic matrix. Exhaustive solvent extraction of the isolated HA proved mandatory to avoid biased results when identifying the origin of the pyrolyzates of untreated samples.

Investigation of the solvent extracts of humic organic matter (HOM) isolated from the Ravenna Lagoon to study environmental pollution and microbial communities.

Solvent extracts of HOM isolated from highly polluted sediments from the Ravenna Lagoon were studied. Diagnostic indicators included polycyclic aromatic hydrocarbons (PAHs) and nonylphenols as hazardous organic pollutants to characterize anthropogenic pollution, as well as fatty acids (FA, analysed as methyl esters, FAME) to characterize microbial communities responsible for natural attenuation processes. The distribution of PAHs including cyclopentafused surrogates pointed to a significant pyrogenic origin, characteristic for methane combustion.

Molecular composition of leaves and stems of genetically modified Bt and near-isogenic non-Bt maize--characterization of lignin patterns.

Transformation of crops, including maize (Zea mays L.), with the cry1Ab gene from Bacillus thuringiensis to combat lepidopteran pests results in pleiotropic effects regarding lignin biosynthesis. Lignin patterns in stems and leaves of two genetically modified Bt-maize varieties (Novelis T and Valmont T) were studied along with their non-Bt near-isolines (Nobilis and Prelude, respectively).

Characterization of non-discriminating tetramethylammonium hydroxide-induced thermochemolysis-capillary gas chromatography-mass spectrometry as a method for profiling fatty acids in bacterial biomasses.

Thermochemolysis using tetramethylammonium hydroxide (TMAH) as a method for profiling fatty acids (FAs) as methyl esters (FAMEs) was studied with respect to discrimination of bacterial fatty acid patterns in Gram-negative Pseudomonas putida in comparison with patterns obtained by classical preparation schemes (pressurized solvent extraction, alkaline saponification). A new, non-discriminating pyrolysis approach was used in these experiments. In this method, pyrolysis is carried out inside a deactivated stainless steel capillary constituting a part of the column train.