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PubMed2003

Residue analysis of the pharmaceutical diclofenac in different water types using ELISA and GC-MS.

A highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of diclofenac in water samples was developed. With pure water, the limit of detection (LOD, S/N = 3) and IC50 were found to be 6 ng/L and 60 ng/L, respectively. The analytical working range was about 20-400 ng/L. Highest cross-reactivity (CR) of 26 tested pharmaceuticals, metabolites, and pesticides was found for 5-hydroxydiclofenac (100%). Other estimated values were well below 4% and, therefore, are negligible. The assay was applied for the determination of diclofenac in tap and surface water samples as well as wastewater collected at 20 sewage treatment plants (STPs) in Austria and Germany. Humic substances were identified as main interference in surface water. Wastewater samples which were only submitted to filtration and dilution yielded about 25% higher diclofenac concentrations using the ELISA compared to GC-MS. However, the ELISA turned out to be a simple, inexpensive, and accurate method for the determination of diclofenac both in influent and effluent wastewater after rather simple sample preparation, i.e., filtration, acidification, and readjustment to neutral pH-value, and at least 10-fold dilution with pure water.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2004

Evidence for pi-pi electron donor-acceptor interactions between pi-donor aromatic compounds and pi-acceptor sites in soil organic matter through pH effects on sorption.

Elucidation of molecular-level interactions controlling the sorption of organic compounds in soils is of major theoretical and practical interest. Sorption of pi-electron donor compounds, pentamethylbenzene (PMB), naphthalene (NAPH), and phenanthrene (PHEN), in a number of soils was found to increase with decreasing pH in the range of approximately pH 2.5-7. This behavior could not be attributed to pH-dependent alteration of the hydrophobic character of humic substances, pi-H-bonding, interaction with mineral surfaces, interaction with black carbons, solute coplanarity, or pH effects on solute activity coefficient. No significant effect of pH was observed for non-pi-donor hydrophobic compounds, whether planar or not: trans-1,2-dichlorocyclohexane (DCCH), hexachloro-1,3-butadiene (HCBD), 1,2,4-trichlorobenzene (TCB), 2,2',5,5'-tetrachlorobiphenyl, and 3,3',4,4'-tetrachlorobiphenyl. The opposite pH effect was observed for 2-nonanol and 2-nonanone, which are non-pi-donors, but capable of H-bonding. Also, no pH-dependent sorption was observed between the pi-donor PHEN and alumina, a model inorganic surface. We propose that the pi-donor solutes interact with pi-acceptor sites in soil organic matter (SOM), including aromatic rings with multiple carboxyl groups, aromatic amines, or heteroaromatic amines. The pi-acceptor ability of such aromatic moieties would increase with protonation. pi-pi Interactions between PMB, NAPH, and PHEN, and model SOM acceptors, 1,3,5-benzenetricarboxylic acid (BTA), 1,4,5,8-naphthalenetetracarboxylic acid (NTA), and pyridine (PY) in methanol and methanol-water, were verified by the appearance of pH-dependent upfield 1H NMR chemical shifts induced by ring current effects. UV/vis spectra showed pH-dependent charge-transfer bands for various donors with NTA. No NMR shifts or charge-transfer bands were found for nondonor compounds paired with the model acceptors.

Adsorption↗

PubMed2005

Desorption kinetics of Cd, Zn, and Ni measured in soils by DGT.

DGT (diffusive gradients in thin films) was used to measure the distribution and rates of exchange of Zn, Cd, and Ni between solid phase and solution in five different soils. Soil texture ranged from sandy loam to clay, pH ranged from 4.9 to 7.1, and organic carbon content ranged from 0.8% to 5.8%. DGT devices continuously remove metal to a Chelex gel layer after passage through a well-defined diffusion layer. The magnitude of the induced remobilization flux from the solid phase is related to the pool size of labile metal and the exchange kinetics between dissolved and sorbed metal. DGT devices were deployed over a series of times (4 h to 3 weeks), and the DIFS model (DGT induced fluxes in soils) was used to derive distribution coefficients for labile metal (Kdl) and the rate at which the soil system can supply metal from solid phase to solution, expressed as a response time. Response times for Zn and Cd were short generally (<8 min). They were so short in some soils (<1 min) that no distinction could be made between supply of metal being controlled by diffusion or the rate of release. Generally longer response times for Ni (5-20 min) were consistent with its slow desorption. The major factor influencing Kdl for Zn and Cd was pH, but association with humic substances in the solid phase also appeared to be important. The systematic decline, with increasing pH, in both the pool size of Ni available to the DGT device and the rate constant for its release is consistent with a part of the soil Ni pool being unavailable within a time scale of 1-20 min. This kinetic limitation is likely to limit the availability of Ni to plants.

Cadmium↗

PubMed2005

Biodegradability of fractions of dissolved organic carbon leached from decomposing leaf litter.

Dissolved organic matter leached from decomposing organic matter is important in the leaching of nutrients from the root zone of ecosystems, eluviation of metals, and transport of hydrophobic pollutants. The objective of this study was to compare microbial mineralization rates in intact soil cores of various fractions of water-soluble dissolved organic matter. Uniformly 14C-labeled Populus fremontii leaf litter that had decomposed for 1 year was extracted in water and this extract was fractionated into phenolic, humic acid, fulvic acid, hydrophilic acid, and hydrophilic neutral fractions. Fulvic acid comprised 42.1% of C in dissolved organic carbon (DOC) extracted from the litter. These fractions were added to intact cores of soil or sand, and respired 14CO2 was collected. The percentage of labeled substrate C mineralized in soil at the end of 1 year was, in order from least to greatest, hydrophilic acid (30.5), fulvic acid (33.8), humic acid (39.0), whole, unfractionated DOC (43.5), unseparated hydrophilic acid and neutral (44.7), phenolic (63.3), glucose (66.4), and hydrophilic neutral (70.2). In acid-washed nutrient-amended sand that was inoculated with soil microbes, mineralization rates of fulvic acid and glucose were lower. The fractionation appeared to separate the DOC into components with widely different rates of mineralization. Results also supported the ideas that the dissolved humic substance and hydrophilic acid fractions are inherently difficult for microbes to mineralize, and this property can contribute to movement of refractory C in soil and into aquatic ecosystems.

Biodegradation, Environmental↗

PubMed2006

Size-based speciation of natural colloidal particles by flow field flow fractionation, inductively coupled plasma-mass spectroscopy, and transmission electron microscopy/X-ray energy dispersive spectroscopy: colloids-trace element interaction.

Flow field flow fractionation (FIFFF), inductively coupled plasma-mass spectroscopy (ICP-MS), and transmission electron microscopy (TEM) coupled to X-ray energy dispersive spectrometry (X-EDS) are used in series for the first time to characterize colloids. Results demonstrate the utility of FIFFF-ICP-MS-TEM/X-EDS to relate physical properties (size) of colloids to their chemical properties (chemical composition, surface chemical composition, and colloids-trace elements association). Results suggest that the major part of natural organic matter (NOM) is concentrated in the fraction < 0.01 microm (C2). Aluminum, iron, and manganese are the main colloidal components in the fraction 0.01-0.45 microm (C1). Aluminum occurs as aluminum oxides or aluminosilicates in the whole size range, while iron and manganese occur as individual oxyhydroxides in the size range < 0.20 microm. Within the C2 fraction, Al, Mn, Cu, and Ni elements are complexed to NOM (e.g., humic substances). Iron is complexed to NOM in some samples and probably free in other samples. Lead is totally free in all samples. Within the C1 fraction, Cu and Pb are mostly associated to Fe and Mn oxyhydroxides. Consequently, NOM with Fe and Mn oxyhydroxides are the main colloidal carriers of trace elements in the Loire watershed system.

Colloids↗

PubMed2006

Effect of accelerated aging of MSWI bottom ash on the leaching mechanisms of copper and molybdenum.

The effect of accelerated aging of Municipal Solid Waste Incinerator (MSWI) bottom ash on the leaching of Cu and Mo was studied using a "multisurface" modeling approach, based on surface complexation to iron/aluminum (hydr)oxides, mineral dissolution/precipitation, and metal complexation by humic substances. A novel experimental method allowed us to identify that the solid/liquid partitioning of fulvic acids (FA) quantitatively explains the observed beneficial effect of accelerated aging on the leaching of Cu. Our results suggestthat iron/aluminum (hydr)oxides are the major reactive surfaces that retain fulvic acid in the bottom ash matrix, of which the aluminum (hydr)oxides were found to increase after aging. A new modeling approach, based on the surface complexation of FA on iron/aluminum (hydr)oxides is developed to describe the pH-dependent leaching of FA from MSWI bottom ash. Accelerated aging results in enhanced adsorption of FA to (neoformed) iron/aluminum (hydr)oxides, leading to a significant decrease in the leaching of FA and associated Cu. Accelerated aging was also found to reduce the leaching of Mo, which is also attributed to enhanced adsorption to (neoformed) iron/aluminum (hydr)oxides. These findings provide important new insights that may help to improve accelerated aging technology.

Adsorption↗

PubMed2006

Donnan membrane approach: from equilibrium to dynamic speciation.

Metal ion toxicity is not simply related to the total concentration but to the free or labile metal ion concentration. One of the techniques that can measure the free metal ion concentration is the Donnan Membrane Technique (DMT). However, this method has limitations in terms of a relatively high detection limit (in relation to typical environmental concentrations) and a long equilibration time. We have therefore developed the Flux Donnan Membrane (FDM) Technique, which is a dynamic modification of the standard DMT with improved detection limits and a more rapid response. We show that experimental calibrations of metal ion transport in the FDM can be used to measure [M]free under conditions of either solution-controlled or membrane-controlled diffusive transport. The FDM was used to measure cobalt binding isotherms by a humic substance over a large range of free Co concentrations and pH.

Calibration↗

PubMed2006

A density functional study of uranyl monocarboxylates.

We studied uranium(VI) monocarboxylate complexes by a relativistic density functional method using simple carboxylic acids as ligands, i.e. [UO2(OOCR)]+ (R = H, CH3, CH2CH3). These complexes exist in aqueous solution and, for R = CH3 and CH2CH3, may also be considered as models of uranyl complexated by humic substances. We investigated mono- and bidentate coordination modes. Short-range solvent effects were accounted for explicitly via aqua ligands of the first hydration shell and long-range electrostatic interactions were described via a polarizable continuum model. The calculated results for the uranyl U=O bond, the bond to aqua ligands, and the averaged uranium distances to equatorial oxygen atoms, U-Oeq, agreed quite well with EXAFS-derived interatomic distances. However, the uranyl-carboxylate bond was calculated to be notably shorter than the experimentally determined value. Experimental differences between mono- and bidentate coordination, obtained mainly from crystal structures, were qualitatively reproduced for the U-C distance but not for the average bond length, U-Oeq. We discuss these discrepancies between calculated and experimental results in some detail and suggest changes in the coordination number rather than variations of the coordination geometry as the main source of the experimentally observed variation of the U-Oeq distance.

Carboxylic Acids↗

PubMed2001

Physicochemical factors affecting the sensitivity of Ceriodaphnia dubia to copper.

The effects of physicochemical conditions, such as pH, water hardness, flow rates and natural organic substances on the sensitivity of Ceriodaphnia dubia to the toxic effects of copper were investigated using static bioassay cups and specially designed flow-through bioassay chambers. We found that C. dubia was very sensitive to pH changes and the total copper LC50 values of C. dubia neonates increased by 15-fold as the pH increased from pH 7 to 10. It was also observed that the LC50 values increased sharply upon increasing the water hardness value to 2.4 meq. In addition, increasing flow rates from zero to 50 mL hr(-1) also increased its sensitivity to copper, which was possibly due to hydrodynamic stress. The presence of natural organic substances (humic acid and dissolved organic matter) and suspended particles decreased the toxic effect of copper. This significant decrease in the toxicity of copper in the presence of natural organic materials can be explained by a reduction in the free ion concentration due to complexation. Furthermore, we observed that the kinetics of copper interactions with natural organic materials are a significant factor in the toxic effect of copper and that the acute LC50 values increased with increasing reaction time between solubilized copper and water-borne organics.

Animals↗

PubMed2001

Effects of olive mill wastewater addition in composting of agroindustrial and urban wastes.

In order to study the suitability of olive mill wastewater (OMW) for composting, this liquid waste was added to two different mixtures of agroindustrial and urban wastes and the composting process was compared with two other piles of similar composition, but without OMW. These four piles were studied in a pilot plant using the Rutgers static pile system. The addition of OMW produced a greater proportion of degradable organic matter or a higher degradation rate, higher electrical conductivity values, greater losses of total N and lower nitrification than in piles without OMW. Its addition also restricted the increase of the cation exchange capacity and provoked the appearance of phytotoxicity or a longer persistence of phytotoxicity. However, in general, all the composts showed increases in the cation exchange capacity, the percentage of humic acid-like carbon, the polymerisation ratio of these humic substances (which revealed that the organic matter had been humified during composting) and the germination index, the latter indicating the reduction of phytotoxicity during the process.

Agriculture↗

PubMed1992

Size, morphology and composition of particulates in aquatic ecosystems: solving speciation problems by correlative electron microscopy.

Particulates can impact directly on aquatic ecosystems by determining the availability and mode of dispersion of both contaminants and nutrients. An understanding of the mechanisms of such particle-associated phenomena is being augmented by particle analysis technology. In this context, microscopic and spectroscopic techniques, devised for problem solving, are being applied to frequently encountered sub-micrometre particulates which are 'unstable' with respect to methods of sample preparation and storage used routinely for particulates prior to analysis. These unstable aquatic particulates include 'species' sensitive to dehydration and to artificial aggregation induced by surfaces within a fractionation apparatus. These species, as defined broadly, include polysaccharide gels, hydrated humic substances, iron oxyhydroxides, viruses, the smallest micro-organisms and decomposing parts of cells. To develop predictive models of their roles as dispersing agents for contaminants, and to speciate such associations, it is necessary to characterize them in a state as close to the natural as possible. This critical review presents the state-of-the-art in the realistic characterization of hydrated sub-micrometre particulates by correlative electron microscopy (EM) used in conjunction with spectroscopy and minimally perturbing preparatory techniques. Correlative EM is a strategy for using several different kinds of microscopes and accessory techniques in a multi-method context to analyse a given specimen for different kinds of information, including relationships in three dimensions within colloid systems. Sizing, morphology and gross composition are determined on a 'per particle' basis by transmission EM used in conjunction with energy-dispersive spectroscopy, electron diffraction and molecule-specific stains.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2000

Structural characterisation of macromolecular organic material in air particulate matter using Py-GC-MS and solid state 13C-NMR.

Organic air particulate matter was analysed by applying the techniques of Py-GC-MS (pyrolysis-gas chromatography-mass spectrometry) and solid state 13C-NMR (nuclear magnetic resonance). Particles dislodged from air particulate filters and humic acid extracted from these filters were studied for structural components. The structural components of the air particles and extracted humic acid consisted of compounds originating from biomacromolecules, namely, lignin, carbohydrates, protein and lipids. The main components identified for each class included: (1) methoxyphenols originating from lignin; (2) furans, aldehydes and ketones from carbohydrates; (3) pyrrole, indoles from protein; and (4) many hydrocarbons from lipid structures. Single ion monitoring (SIM) and tetramethyl ammonium hydroxide (TMAH) methylation were utilised for detection of aliphatic hydrocarbons and acidic components, respectively. Hydrocarbons ranging from C9 to C28 were detected by SIM analysis, while aliphatic acids ranged from C9 to C18. The majority of components analysed directly in the air particles were similar to those from the humic acid extracts. Many of the structural components of air particles were typical of humic substances of soil and aqueous systems and these were attributed to both biogenic and anthropogenic sources.

Air Pollution↗

PubMed2001

Partitioning of mercury onto suspended sediments in estuaries.

Radiochemical partitioning experiments using 203Hg have been undertaken with mixtures of river, seawater and sediment samples taken from three geochemically contrasting UK estuaries: the Plym, Beaulieu and Mersey. Species of dissolved Hg were determined using reversed-phase C18 chelating columns and particulate species were determined by sequential leaching with 1 M NH4OAc and 1 M HCl. Mercury had a high particle reactivity with partition coefficients, KDs, ranging from 10(4) to 5 x 10(5) ml g(-1), depending on salinity, the chemical composition of the end-member waters, and on the physico-chemical characteristics of the sediment. Dissolved organic matter present in the waters (humic substances and/or anthropogenic compounds) was found to be the main factor governing the forms of dissolved Hg and their reactivity. From the spiked 203Hg, up to 95% of the dissolved metal was retained on the C18 columns for the Mersey waters, whereas this fraction was < 60% in the Plym and Beaulieu waters. Quasi-irreversible adsorption of Hg onto particles from each estuary was observed over a time-scale of a few hours and < 20% of total particulate Hg was released by the sequential leach. In this paper, physico-chemical processes are proposed to explain the estuarine behaviour of Hg and the results are discussed in terms of Hg availability in estuarine systems.

Adsorption↗

PubMed2003

Effects of organic ligands and pH on the leaching of copper from brake wear debris in model environmental solutions.

Copper leaching from a disc brake wear debris sample was examined in a variety of aqueous solutions to simulate potential leaching processes during rain events and in surface waters. Synthetic rainwater leached 40% of the total copper present in the brake wear debris into solution after 18 h in batch reactors, which was approximately three times more copper than that extracted by the US Environmental Protection Agency's Synthetic Precipitation Leaching Procedure. Formate and acetate were responsible for the enhanced copper leaching, as demonstrated by higher average amounts of leached copper in synthetic rainwater with- versus without the organic acids (40 versus 31% recovery). This observation suggests leaching tests that do not incorporate the appropriate types and concentrations of organic ligands present in rainwater will likely underestimate copper mobilization from brake wear debris during rain events. Leaching of copper from the brake wear debris ranged from 23 to 40% in solutions containing 3 to 15 mg C L(-1) dissolved humic substances, and was higher still in solutions containing relatively high concentrations of the synthetic metal chelating agent ethylenediaminetetraacetic acid. Static pH tests demonstrated that copper leaching from brake wear debris is highly pH dependent, with more leaching occurring at lower solution pH values. Leaching rate studies revealed that equilibrium generally was not attained within 48 h in the model solutions, indicating that additional copper can be expected to be released in environments where brake wear debris is exposed to long-term leaching processes.

Copper↗

PubMed2004

Catechin and hydroxybenzhydrols as models for the environmental photochemistry of tannins and lignins.

The photochemistry of several model plant-derived compounds has been studied in aqueous solution. In particular, the reactions of catechin as a model tannin and methoxy-substituted hydroxybenzhydrols as model lignin functionalities were investigated. Tannins and lignins constitute a significant portion of the humic substances in aquatic systems, which are themselves the main component of dissolved organic matter thought to be responsible for the absorption and attenuation of light in these environments. Catechin (1) was found to undergo a reversible photoisomerization reaction to give epicatechin (2). Such a reaction is an explicit example of a photon absorbing process that enables catechin (1) and its derivatives to act as natural sunscreens by attenuating light energy through non-destructive reactions. The methoxy-substituted hydroxybenzhydrols were found to undergo photosolvolysis reactions via efficient generation of quinone methide intermediates. The intermediate quinone methides were observed to be longer lived, and thus more stable, than previously studied hydroxybenzhydrol derivatives. The meta-hydroxybenzhydrol isomer (5) was found to undergo additional chemistry leading to the production of a ring-closed fluorene from the quinone methide intermediate.

Journal Article↗

PubMed2000

Microbial succession during a composting process as evaluated by denaturing gradient gel electrophoresis analysis.

Microbial succession during a laboratory-scale composting process of garbage was analysed by denaturing gradient gel electrophoresis (DGGE) combined with measurement of physicochemical parameters such as temperature, pH, organic acids, total dissolved organic carbon and water-soluble humic substance. From the temperature changes, a rapid increase from 25 to 58 degrees C and then a gradual decrease, four phases were recognized in the process as follows; mesophilic (S), thermophilic (T), cooling (C) and maturing (M). The polymerase chain reaction-amplified 16S rDNA fragments with universal (907R) and eubacterial (341F with GC clamp) primers were subjected to DGGE analysis. Consequently, the DGGE band pattern changed during the composting process. The direct sequences from DGGE bands were related to those of known genera in the DNA database. The microbial succession determined by DGGE was summarized as follows: in the S phase some fermenting bacteria, such as lactobacillus, were present with the existing organic acids; in the T phase thermophilic bacillus appeared and, after the C phase, bacterial populations were more complex than in previous phases and the phylogenetic positions of those populations were relatively distant from strains so far in the DNA database. Thus, the DGGE method is useful to reveal microbial succession during a composting process.

Bacteria↗

PubMed1999

Reduction of (per)chlorate by a novel organism isolated from paper mill waste.

As part of a study on the microbiology of chlorate reduction, several new dissimilatory chlorate-reducing bacteria were isolated from a broad diversity of environments. One of these, strain CKB, was selected for a more complete characterization. Strain CKB was enriched and isolated from paper mill waste with acetate as the sole electron donor and chlorate as the sole electron acceptor. Strain CKB is a completely oxidizing, non-fermentative, Gram-negative, facultative anaerobe. Cells of strain CKB are 0.5 x 2 microm and are highly motile, with a single polar flagellum. In addition to acetate, strain CKB can use propionate, butyrate, lactate, succinate, fumarate, malate or yeast extract as electron donors, with chlorate as the sole electron acceptor. Strain CKB can also couple chlorate reduction to the oxidation of ferrous iron, sulphide, or the reduced form of the humic substances analogue 2,6-anthrahydroquinone disulphonate. Fe(II) is oxidized to insoluble amorphous Fe(II) oxide, whereas sulphide is oxidized to elemental sulphur. Growth is not associated with this metabolism, even when small quantities of acetate are added as a potential carbon source. In addition to chlorate, strain CKB can also couple acetate oxidation to the reduction of oxygen or perchlorate. Chlorate is completely reduced to chloride. Strain CKB has an optimum temperature of 35 degrees C, a pH optimum of 7.5 and a salinity optimum of 1% NaCl. Strain CKB can grow in chlorate and perchlorate concentrations of 80 or 20 mM respectively. Under anaerobic conditions, strain CKB can dismutate chlorite into chloride and O2, and is only the second organism shown to be capable of this metabolism. Oxidized minus reduced spectra of whole-cell suspensions of strain CKB showed absorbance maxima at 423, 523 and 552nm, which are indicative of the presence of c-type cytochrome(s). Analysis of the complete sequence of the 16S rDNA indicates that strain CKB is a member of the beta subclass of the Proteobacteria. The phototroph Rhodocyclus tenuis is the closest known relative. When tested, strain CKB could not grow by phototrophy and did not contain bacteriochlorophyll. Phenotypically and phylogenetically, strain CKB differs from all other described bacteria and represents the type strain of a new genus and species.

Betaproteobacteria↗

PubMed1999

Characterization of complex mineral assemblages: implications for contaminant transport and environmental remediation.

Surface reactive phases of soils and aquifers, comprised of phyllosilicate and metal oxohydroxide minerals along with humic substances, play a critical role in the regulation of contaminant fate and transport. Much of our knowledge concerning contaminant-mineral interactions at the molecular level, however, is derived from extensive experimentation on model mineral systems. Although these investigations have provided a foundation for understanding reactive surface functional groups on individual mineral phases, the information cannot be readily extrapolated to complex mineral assemblages in natural systems. Recent studies have elucidated the role of less abundant mineral and organic substrates as important surface chemical modifiers and have demonstrated complex coupling of reactivity between permanent-charge phyllosilicates and variable-charge Fe-oxohydroxide phases. Surface chemical modifiers were observed to control colloid generation and transport processes in surface and subsurface environments as well as the transport of solutes and ionic tracers. The surface charging mechanisms operative in the complex mineral assemblages cannot be predicted based on bulk mineralogy or by considering surface reactivity of less abundant mineral phases based on results from model systems. The fragile nature of mineral assemblages isolated from natural systems requires novel techniques and experimental approaches for investigating their surface chemistry and reactivity free of artifacts. A complete understanding of the surface chemistry of complex mineral assemblages is prerequisite to accurately assessing environmental and human health risks of contaminants or in designing environmentally sound, cost-effective chemical and biological remediation strategies.

Journal Article↗