Mercury transport through a porous medium in presence of natural organic matter

Natural organic matter (NOM), derived from degradation of living organism matter, can significantly control the fate and transport of chemical components, particularly metal ions, by forming organometallic complexes in aquatic systems. Column experiments were performed to study the mobility of humic acids (HA) and Hg. Single component (HA or Hg) and multicomponent (Hg and HA) experiments were conducted to assess transport behaviour of Hg in the presence of HA. A natural quartz sand was used as porous sorbing medium. HA breakthrough curves (BTCs) showed a first step with a sharp front followed by an important tailing over a long period of time. The tailing of HA BTCs is assumed to be due to slow sorption kinetics of HA onto the quartz sand and the non linear nature of the sorption isotherms. The time required to get steady-state concentration for organic C depended on the inlet HA concentration. HA sorption depends also on pH, the highest HA sorption being observed at $\rm pH<pH_{\rm pzc}$ due to electrostatic attractions. The Hg transport is strongly enhanced in the presence of HA and the Hg BTCs are quite similar to the HA BTCs. These results suggest strong aqueous complexation between Hg and HA and the formation of ternary surface complexes of type B

Fractionation and characterization of ozonated and post chlorinated aquatic fulvic acid using gel chromatography

Extracted aquatic fulvic acid samples (HO10FA) from a brown lake Hohloh in the Black Forest (Germany) were ozonated at two different ozone doses and then chlorinated. In connection with liquid chromatography and further detection systems (UV and DOC) on gel matrix, a combined system (gel chromatography) was used for a detailed characterization of ozonated and post-chlorinated fulvic acid samples. The gel chromatographic characterization showed a slight decrease in DOC (14%) and SAC254 (36%) at the end of 20 min ozonation whereas the low ozonation time (5 min) caused increased in DOC (6%) and SAC254 (56%).Extracted aquatic fulvic acid samples (HO10FA) from a brown lake Hohloh in the Black Forest (Germany) were ozonated at two different ozone doses and then chlorinated. In connection with liquid chromatography and further detection systems (UV and DOC) on gel matrix, a combined system (gel chromatograpy) was used for a detailed characterization of ozonated and post-chlorinated fulvic acid samples. The gel chromatographic characterization showed a slight decrease in DOC (14%) and SAC254 (36%) at the end of 20 min ozonation whereas the low ozonation time (5 min) caused increases in DOC (6%) and SAC254 (56%).German Academic Exchange Service London Deutscher Akademischer Austauschdienst Deutsche ForschungsgemeinschaftThe authors thank the 32nd International Seminar(IS), German Academic Exchange Service (DAAD) and Deutsche Forschungsgemeinschaft (DFG, ROSIG) for financial support. We are grateful to Sebastian Hesse for experimental assistance

Use of gel permeation chromatography to characterize the changes in natural organic matter through oxidative treatments

Gel permeation chromatography (GPC) in combination with ultraviolet (UV) and sensitive dissolved organic carbon (DOC) detection was used to investigate the structural changes caused by ozonation and chlorination. Oxidation processes were applied to a fulvic acid (HO10FA) sample which was extracted from Hohloh Lake, Germany. Biological degradation by means of assimilable organic carbon (AOC) of the FA sample was monitored by GPC elution diagrams. It is shown that ozonation and subsequent chlorination result in partial decomposition of the high-molecular-mass components of FA to low-molecular-mass hydrophilic compounds which are more biodegradable by microorganisms

Fluorescence of humic acids (HA) and pyrene-HA complexes at ultralow temperature

The interaction of pyrene with humic acids of different origins was investigated using fluorescence line narrowing (FLN) spectroscopy at 10 K. FLN spectroscopy can be used to obtain vibrationally resolved fluorescence spectra from samples that under ordinary conditions suffer from extensive spectral broadening. Due to the presence of humic acid the site distribution and the relative intensities of the ground-state vibrations in the fluorescence spectrum (Ham-effect) of pyrene were changed. Both effects were related to the altered microenvironment of pyrene in the presence of humic acid. On the other hand, for humic acids no fluorescence line narrowing effect was observed indicating the occurrence of intra- and intermolecular processes

Sanierungstechnologien fuer anorganische Schadstoffe im Untergrund. Teilvorhaben 2: In-situ-Immobilisierung von Arsenverbindungen im wassergesaettigten Bereich Abschlussbericht

SIGLEAvailable from TIB Hannover: F02B1525+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Weitergehende Oxidationsverfahren in der Trinkwasseraufbereitung -Desinfektionsmittelminimierung und Verringerung des Wiederverkeimungspotentials. Bd. 2. T. 4: Vergleich der Oxidationsverfahren Abschlussbericht

The different Advanced Oxidation Processes (AOP), which produce OH-radicals by a combination of conventional oxidants, were compared with oxonation. The ozone/hydrogen peroxide (peroxone) process, the ozone/UV- and the hydrogen peroxide/UV process were examined. The removal of micropollutants (EDTA, diuron) in water of the river Ruhr, was nearly similar using ozone and peroxone, respectively. The degree of removal of EDTA after the peroxone process was higher than after ozonation. Diuron was removed more effectively by ozone. The removal of micropollutants with UV-based AOP was less effective than with ozone and peroxone, respectively. An effective application of the peroxone process needs an absorbed ozone mass of at least 1 mg/mg DOC. Otherwise the hydrogen peroxide consumption is too low. For quantifying the influence of preoxidation on the formation of disinfection by-products (DBP) the THM- and AOX-formation potential were examined. The most effective removal of precursors for DBP was achieved using ozonation alone. In the peroxone process the DBP formation increases in comparison to ozonation with an increasing addition of hydrogen peroxide. An increasing THM-formation was observed using the hydrogen peroxide/UV process with short irradiation time. A reduction of DBP formation was observed after long irradiation times and a high hydrogen peroxide consumption. An effective removal of DBP precursors in this process is only possible using a higher energy input compared to ozonation. The regermination potential is lower after AOP than after ozonation. However, every oxidation process increases the regermination potential. The application of oxidation processes without a following biological treatment step should be avoided. (orig.)SIGLEAvailable from TIB Hannover: F00B423 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Engler-Bunte-Institut der Universitaet Karlsruhe (TH). Das Institut im Jahre 1991

SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Metabolites indicate hot spots of biodegradation and biogeochemical gradients in a high-resolution monitoring well.

Anaerobic degradation processes play an important role in contaminated aquifers. To indicate active biodegradation processes signature metabolites can be used. In this study field samples from a high-resolution multilevel well in a tar oil-contaminated, anoxic aquifer were analyzed for metabolites by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry. In addition to already known specific degradation products of toluene, xylenes, and naphthalenes, the seldom reported degradation products benzothiophenemethylsuccinic acid (BTMS), benzofuranmethylsuccinic acid (BFMS), methylnaphthyl-2-methylsuccinic acid (MNMS), and acenaphthene-5-carboxylic acid (AC) could be identified (BFMS, AC) and tentatively identified (BTMS, MNMS). The occurrence of BTMS and BFMS clearly show that the fumarate addition pathway, known for toluene and methylnaphthalene, is also important for the anaerobic degradation of heterocyclic contaminants in aquifers. The molar concentration ratios of metabolites and their related parent compounds differ over a wide range which shows that there is no simple and consistent quantitative relation. However, generally higher ratios were found for the more recalcitrant compounds, which are putatively cometabolically degraded (e.g., 2-carboxybenzothiophene and acenaphthene-5-carboxylic acid), indicating an accumulation of these metabolites. Vertical concentration profiles of benzylsuccinic acid (BS) and methyl-benzylsuccinic acid (MBS) showed distinct peaks at the fringes of the toluene and xylene plume indicating hot spots of biodegradation activity and supporting the plume fringe concept. However, there are some compounds which show a different vertical distribution with the most prominent concentrations where also the precursor compounds peaked