Use of Chemotaxonomy To Study the Influence of Benzalkonium Chloride on Bacterial Populations in Biodegradation Testing

Contradictory results are reported for the behaviour of quaternary ammonium compounds (QACs) in sewage treatment plants (STPs). QACs may sorb onto activated sludge. Only little information is available with respect to effects of QACs against bacteria in STPs. Only 5 to 15 % of bacteria present in sewage sludge can be detected by means of culture dependent microbiological methods. The shift of the bacterial populations due to effects of test compounds have not been studied up to now with culture independent methods. The microbial populations shift was studied in situ using culture independent chemotaxonomy profiling ubiquinones and polyamines. Additionally, toxic effects of QACs against bacteria present in the test vessels of the Zahn‐Wellens test (OECD 302 B) were assessed with a toxicity control in the test. The ubiquinone profiles representing changes in Gram‐negative populations mainly showed that the activated sludge was affected only in test vessels containing benzalkonium chloride. According to chemotaxonomy Acinetobacter or/and some members of Pseudomonas spp. have been selected by benzalkonium chloride after some adaptation period (8 to 12 days).     

Graphite content and isotopic fractionation between calcite-graphite pairs in metasediments from the Mgama Hills,Southern Kenya

Amphibolite-grade metasediments from the Mgama Hills region, Kenya, contain conspicuous quantities of graphite, most probably derived from organic progenitor materials. The highest graphite contents (5.1–20.4%) are found in schists whereas calcite marbles intercalated in the sequence contain relatively low amounts (0.1–2.0%). The graphitic constituents are consistently enriched in ¹³C relative to common sedimentary organic material, with the highest isotopic ratios in graphite from the marbles (δ¹³C = ?7.3 ± 5.0%.; n = 10). Carbon isotope fractionations between calcite and graphite mostly vary between 3.3 and 7.1‰, which comes close to both empirically recorded and thermodynamically calculated fractionations in the temperature range of the upper amphibolite faciès (550–650°C). However, larger values occasionally encountered in the marbles suggest that complete isotopic equilibrium is not always attained in amphibolite-facies metamorphism.     

Geochemical environment of Cenomanian - Turonian black shale deposition at Wunstorf (northern Germany)

Major- and minor- element determinations were carried out on a high-resolution sample set obtained from a sediment drill core at Wunstorf (N. Germany). This study interval includes the black shale-bearing Hesseltal Formation associated with the Oceanic Anoxic Event 2 (OAE 2), also referred to as Cenomanian-Turonian Boundary Event (CTBE). Seven black shale packages, each containing several black shale layers, were defined by elevated TOC values, with black shale packages 1-4 deposited during OAE 2. Packages 5-7 extend above the level of the positive carbon-isotope excursion defining OAE 2, indicating that conditions favouring organic carbon burial must have prevailed longer in the Wunstorf Basin than elsewhere. Geochemical analyses revealed no significant differences between black shale packages deposited during and after OAE 2. Enrichment patterns of sulphur, iron and redox-sensitive and sulphide-forming trace metals point to suboxic to anoxic conditions existing at the sediment-water interface during black shale deposition, whereas sulphidic conditions prevailed deeper in the sediment. Variations in element/Al ratios follow cyclic patterns which are interpreted to represent climatically-induced changes in sediment supply. Reduced vertical mixing led to water-column stratification and caused black shale deposition.     

The origin of non-porphyritic pyroxene chondrules in UOCs: Liquid solar nebula condensates?

A total of 56 non-porphyritic pyroxene and pyroxene/olivine micro-objects from different unequilibrated ordinary chondrites were selected for detailed studies to test the existing formation models. Our studies imply that the non-porphyritic objects represent quickly quenched liquids with each object reflecting a very complex and unique evolutionary history. Bulk major element analyses, obtained with EMPA and ASEM, as well as bulk lithophile trace element analyses, determined by LA-ICP-MS, resulted in unfractionated (solar-like) ratios of CaO/Al₂O₃, Yb/Ce as well as Sc/Yb in many of the studied objects and mostly unfractionated refractory lithophile trace element (RLTE) abundance patterns. These features support an origin by direct condensation from a gas of solar nebula composition. Full equilibrium condensation calculations show that it is theoretically possible that pyroxene-dominated non-porphyritic chondrules with flat REE patterns could have been formed as droplet liquid condensates directly from a nebular gas strongly depleted in olivine. Thus, it is possible to have enstatite as the stable liquidus phase in a 800 × Cl dust-enriched nebular gas at a ptot of 10⁻³ atm, if about 72% of the original Mg is removed (as forsterite?) from the system. Condensation of liquids from vapor (primary liquid condensation) could be considered as a possible formation process of the pyroxene-dominated non-porphyritic objects. This process can produce a large spectrum of chemical compositions, which always have unfractionated RLTE abundances. Late stage and subsolidus metasomatic events appear to have furthered the compositional diversity of chondrules and related objects by addition of moderately volatile and volatile elements to these objects by exchange reactions with the chondritic reservoir (e.g., V, Cr, Mn, FeO as well as K and Na). The strong fractionation displayed by the volatile lithophile elements could be indicative of a variable efficiency of metasomatic processes occurring during and/or after chondrule formation. Histories of individual objects differ in detail from each other and clearly indicate individual formation and subsequent processing.     

Stable isotope and organo-geochemical studies on phanerozoic sediments of the Williston Basin,North America

Carbon isotope studies have been carried out on marine Phanerozoic sediments of the Williston Basin, North America. Special attention was given to the recognition of systematic variations with age.δ ¹³C measurements on the carbonate fraction show a 3%₀ depletion from the Cambrian to the Mississippian and a 1–2%₀ enrichment to the Jurassic. Both the sign of these displacements and a good correlation with the organic carbon content suggest that real variations in the rate of photosynthesis may have been the driving force for these changes with age.Because of the large isotopic heterogeneities in the organic biomass, systematic fluctuations with age in the δ ¹³C-values of the total organic carbon record are hard to prove. Nevertheless, a significant 3%₀ depletion was observed from the Devonian to the end of the Carboniferous. This depletion seems to occur on a worldwide scale. It is therefore proposed that a rise in the rate of photosynthesis as a consequence of the colonization of the continents by higher plants is the global cause of this displacement in the isotope record of the total organic carbon.The bitumen fraction does not show any systematic isotope variations with age.Comparison of coexisting δ ¹³C_org?δ ¹³C_bit pairs demonstrates that during the Ordovician-Mississippian time period no significant (> 1%₀) differences in the isotope values of these two organic carbon sources can be observed. In contrast the bitumen fraction is depleted in ¹³C as compared to the total organic carbon in the Cambrian as well as in the Pennsylvanian-Cretaceous time interval. Several parameters, i.e. the depth of burial of these sediments, the $\text{1}\text{2}$(pristane/n-C₁₇ + phytane/n-C₁₈) ratio and the n-alkane distribution pattern support the theory that the rank of the organic matter may be responsible for the observed isotopic pattern.     

Nonporphyritic chondrules from equilibrated Rumuruti and ordinary chondrites: Chemical evidence of secondary processing

Abstract– Nineteen nonporphyritic pyroxene and pyroxene/olivine chondrules, chondrule fragments, and irregular objects were studied from two equilibrated chondrites, the ordinary (L/LL5) Knyahinya chondrite and the Rumuruti type (R4) Ouzina chondrite. Major element contents for almost all objects in the chondrites are disturbed from their chondritic ratios, most probably during metamorphic re‐equilibration. However, the volatile elements (Na₂O + K₂O) in Ouzina scatter around the CI line, probably the result of being generated and/or processed in different environments as compared with those for Knyahinya. All studied objects from Knyahinya and Ouzina possess systematically fractionated trace element abundances. Depletion of LREE with respect to HREE and ultra‐refractory HFSE documents variable degrees of LREE transport into an external mineral sink and restricted mobility of most of the HREE and HFSE. Moderately volatile elements preserve volatility‐controlled abundances. Strongly fractionated Rb/Cs ratios (up to 10× CI) in all studied objects suggest restricted mobility of the large Cs ion. All studied objects sampled and preserved Y and Ho in solar proportions, a feature that they share with the nonporphyritic chondrules of unequilibrated ordinary chondrites.     

Evolution of organic matter degradation in Cretaceous black shales inferred from authigenic barite: A reaction-transport model

A reaction-transport model was used to infer the long-term evolution of anaerobic organic matter degradation in Cretaceous black shales from the distribution of authigenic barite in sediments drilled at Demerara Rise (ODP Leg 207, Site 1258). In these sediments, sulfate-reduction and methanogenesis are the major pathways of organic matter decomposition and the depth-distribution of authigenic barite serves as an indicator for the temporal evolution of the sulfate-methane transition zone (SMTZ), the strength of the biogenic methane flux and, ultimately, the organic matter reactivity in the black shales over geological timescales. Organic matter degradation is described according to the reactive continuum model approach and parameters values are determined by inverse modeling, based on present-day porewater and authigenic barite profiles. Fully transient simulations were performed over a period of 100 Myrs and indicate that important features of the biogeochemical dynamics are associated to changes in the boundary forcing. Hiatuses in sediment accumulation rate result in quasi-steady-state conditions and lead to distinct accumulations of authigenic barites in the SMTZ. The inversely determined parameters reveal that the reactivity of the organic matter was already low (apparent first order rate constant ) at the time of its deposition in the Cretaceous. The geochemical characteristics of sediments drilled at Demerara Rise, as well as the presence of specific biomarkers, suggest that this low reactivity is most likely due to the euxinic palaeo-conditions which favored the sulfurization of the organic matter. Simulation results predict average initial organic carbon contents between 8.1 and 9.5 wt%, implying a high preservation efficiency of the organic matter (between 79% and 89%). Calculated mass accumulation rates (between 0.43 and 0.5 ) compare well with estimations for the western basin of the Cretaceous southern North Atlantic. Simulation results thus indicate that the enhanced preservation of organic matter under euxinic conditions may have been the main cause for the formation of organic-rich Cretaceous black shales at Demerara Rise.     

Variations in the carbon isotope composition and production yield of various pyrolysis products under open and closed system conditions

Production rates and carbon isotopic compositions of various pyrolysis products were investigated for three sediments from the Williston Basin under open and closed pyrolysis conditions in the temperature range of 300–600°C.Both parameters do not show any significant differences for kerogens and carbon dioxides with the analytical procedure. Contrary to open system pyrolysis, however, decreasing yields of pyrolysates and higher amounts of gaseous hydrocarbons (C_2–4 compounds) at temperatures of 500 and 600°C, point to their decomposition to give ultimately methane.Moreover, these pyrolysis products display distinct carbon isotopic variations under open and closed pyrolysis conditions. They are due to a kinetic isotope effect, i.e. the preferential cleavage of ¹²C-¹²C over ¹³C-¹²C bonds, but the extent of the shift in isotopic composition seems to depend primarily on the reservoir size and the type of source material.     

Autecology of Limnomysis benedeni Czerniavsky, 1882 (Crustacea: Mysida) in Lake Constance, Southwestern Germany

The Ponto-Caspian mysid Limnomysis benedeni was first recorded in Lake Constance in summer 2006, and a stable population developed at the site of discovery. Although this mysid is common in the Rhine and Danube rivers, little is known about its ecology and impact in systems of invasion. We investigated the autecology of L. benedeni in habitat-choice and food experiments. In the habitat-choice experiments, highly structured habitats, i.e., stones covered with zebra mussels (Dreissena polymorpha), macrophytes, and especially stonewort, were strongly preferred. In food experiments, L. benedeni fed mostly on food sources with a small particle size, e.g., biofilm on leaf litter, biodeposited material of zebra mussels, epilithon, and phytoplankton. We also compared the L. benedeni population data from Lake Constance with that from rivers. In Lake Constance, female L. benedeni were nearly 30% larger and carried more than three times more eggs in spring (9.4±0.6 mm and 28.4±5.7 eggs) than in summer (6.7±0.8 mm and 8.7±2.9 eggs). The mysids present in spring might be the generation that over-wintered; in summer, this generation was probably replaced by a new generation of smaller individuals. The large brood size and the detritivorous feeding strategy might allow L. benedeni to colonize Lake Constance rapidly.