Barbara M. Scholz-Böttcher

Mono-, di- and trimethyl-branched alkanes in cultures of the filamentous cyanobacterium Calothrix scopulorum

The extractable lipids of the cyanobacterium Calothrix scopulorum contain a complex suite of mono-, di- and trimethylheptadecanes. We identified 21 isomers; most of them have not been reported previously. The major compounds are 4,13-, 5,13-, and 4,5-dimethyl-, and 4,5,13- and 4,5,14-trimethylheptadecane. Methyl substitution occurs preferentially, but not exclusively, at positions 4 and 5 (or ω-4 and ω-5) at either end of the carbon chain. In mass spectra, the location of methyl groups at opposite ends of the carbon chain can be deduced from the presence of a characteristic secondary CnH2n−1+ fragment ion. The interpretation of mass spectra was confirmed by calculated retention index values which closely match the measured data. Our data provide evidence that branched alkanes with 17 to 20 carbon atoms can be used as biomarkers for cyanobacterial contributions to sedimentary organic matter.

Early diagenesis of organic matter and related sulphur incorporation in surface sediments of meromictic Lake Cadagno in the Swiss Alps

Samples of Recent anoxic sediment (< 100 yr BP) from the meromictic Lake Cadagno (Switzerland) were examined to study sulphur incorporation into organic matter at a very early stage of diagenesis. Trace amounts of two organosulphur compounds were identified in the extractable organic matter. Desulphurization of the heterocompound and asphaltene fractions with nickel boride yielded hydrocarbons with a strong dominance of phytane and minor amounts of n-alkanes, steranes and squalane, but may also have converted ester-bound moieties into hydrocarbons as shown by a control experiment with a chloropyll a standard. The amount of sulphur-bound compounds is always higher than the amount of the free precursors, even in the shallowest sediments. This indicates that the formation of organosulphur compounds starts already in the water column or is very effective in the uppermost millimeters of the sediment layer. Stable carbon isotope data of the sedimentary compounds, and of biological material from the water column and from land biota growing around the lake, show that the sulphur-bound phytane in the youngest samples is dominated by phytane of bacterial origin. With increasing depth the amount of phytane of terrestrial origin slightly increases.

The record of climatic change in the geological archives of shallow marine, coastal, and adjacent lowland areas of Northern Germany.

Abstract The record of climatic change in shallow marine, coastal, and adjacent lowland areas has been investigated by three different approaches. A mass balance study focused on the interaction between sea-level rise and Holocene sediment accumulation in the coastal lowland area between the Ems and Weser rivers on the German North Sea coast. This region, which comprises various sedimentary environments, such as barrier islands, sheltered and open tidal flats, bay flats, and estuaries, is highly suitable for such quantitative studies, which can be used to create a model for general mass transport and accumulation processes connected with transgressions over coastal lowlands. An integrated geochemical and microfacies study was made to assess the response of shallow marine, intertidal, and limnic-semiterrestrial environments to the climate-controlled Holocene sea-level rise. The factors controlling the development of various palaeoenvironments were estimated from the distribution of biomarkers, major and trace elements, diatoms, foraminifera and sedimentary structures observed at high resolution in core sections. These data complement those of conventional geological, lithostratigraphical, archaeological and geobotanical investigations. The extensive raised bogs which occur in the Pleistocene hinterland, adjacent to the coastal zone, provided an excellent opportunity to examine peat formation in response to climatic changes in the past. On the basis of a large number of 14 C -age determinations special attention was paid to the onset and regional expansion of raised bogs in this region and to the question of whether or not the formation of raised bog peat started synchronously in one or in a series of different phases.

Simultaneous Trace Identification and Quantification of Common Types of Microplastics in Environmental Samples by Pyrolysis-Gas Chromatography–Mass Spectrometry

The content of microplastics (MP) in the environment is constantly growing. Since the environmental relevance, particularly bioavailability, rises with decreasing particle size, the knowledge of the MP proportion in habitats and organisms is of gaining importance. The reliable recognition of MP particles is limited and underlies substantial uncertainties. Therefore spectroscopic methods are necessary to ensure the plastic nature of isolated particles, determine the polymer type and obtain particle count related quantitative data. In this study Curie-Point pyrolysis-gas chromatography-mass spectrometry combined with thermochemolysis is shown to be an excellent analytical tool to simultaneously identify and optionally quantify MP in environmental samples on a polymer specific mass related trace level. The method is independent of any mechanical preselection or particle appearance. For this purpose polymer characteristic pyrolysis products and their indicative fragment ions were used to analyze eight common types of plastics. Further aspects of calibration, recoveries, and potential matrix effects are discussed. The method is exemplarily applied on selected fish samples after an enzymatic-chemically pretreatment. This new approach with mass-related results is complementary to established FT-IR and Raman methods providing particle counts of individual polymer particles.

Qualitative impact of salinity, UV radiation and turbulence on leaching of organic plastic additives from four common plastics - A lab experiment.

Four common consumer plastic samples (polyethylene, polystyrene, polyethylene terephthalate, polyvinylchloride) were studied to investigate the impact of physical parameters such as turbulence, salinity and UV irradiance on leaching behavior of selected plastic components. Polymers were exposed to two different salinities (i.e. 0 and 35 g/kg), UV radiation and turbulence. Additives (e.g. bisphenol A, phthalates, citrates, and Irgafos® 168 phosphate) and oligomers were detected in initial plastics and aqueous extracts. Identification and quantification was performed by GC-FID/MS. Bisphenol A and citrate based additives are leached easier compared to phthalates. The print highly contributed to the chemical burden of the analyzed polyethylene bag. The study underlines a positive relationship between turbulence and magnitude of leaching. Salinity had a minor impact that differs for each analyte. Global annual release of additives from assessed plastics into marine environments is estimated to be between 35 and 917 tons, of which most are derived from plasticized polyvinylchloride.

Cardiac glycosides from Yellow Oleander (Thevetia peruviana) seeds

Thevetia cardiac glycosides can lead to intoxication, thus they are important indicators for forensic and pharmacologic surveys. Six thevetia cardiac glycosides, including two with unknown structures, were isolated from the seeds of the Yellow Oleander (Thevetia peruviana (Pers.) K. Shum., Apocynaceae). LC-ESI⁺-MS(/MS) analysis under high-resolution conditions used as a qualitative survey of the primary glycosides did not lead to fragmentation of the aglycones. Acid hydrolysis of the polar and non-volatile thevetia glycosides under severe conditions yielded the aglycones of the thevetia glycosides and made them amenable to GC-MS analysis. Comparison of mass spectral fragmentation patterns of the aglycones, as well as high-resolution mass spectrometric and NMR data of four of the primary thevetia glycosides including the two unknowns, revealed the structures of the complete set of six thevetia glycosides. The identified compounds are termed thevetin C and acetylthevetin C and differ by an 18,20-oxido-20,22-dihydro functionality from thevetin B and acetylthevetin B, respectively. The absence of an unsaturated lactone ring renders the glycosides cardio-inactive. The procedures developed in this study and the sets of analytical data obtained will be useful for screening and structure assessment of other, particularly polar, cardiac glycosides.

Lipid biogeochemistry of surface sediments in the Lower Saxonian Wadden Sea, northwest Germany, and the effect of the strong winter 1995–1996

Ice rafting in the Lower Saxonian Wadden Sea, northwest Germany, in winter 1995-1996 had a dramatic effect on surface sediments. At the beginning of a longer-term biogeochemical study, the investigated area (six sampling sites) comprised beds of the mussel Mytilus edulis which disappeared under the severe weather conditions. Large amounts of sediment were eroded and redeposited. Evidence for emplaced biodeposits was given by TOC measurements and molecular distribution profiles of n-and iso/anteiso-fatty acids and of sterols. Absolute concentrations of fatty acids and sterols in 1996 were lower than in 1995, despite a higher organic carbon content in 1996 (> 1.4% compared to 0.8%). This indicates that redeposition was accompanied by a decrease in the labile organic matter fraction by oxidation. After removal of the mussels, the sedimentary organic matter composition was nearly uniform at all sampling sites. This was manifested in n-fatty acid distribution patterns, relative proportions of algal to terrigenous and bacterial acids, cholestanol/cholesterol ratios and sterol distributions. An enormous diatom bloom of Coscinodiscus concinnus in spring 1996 caused an increase in the amounts of n-C 14 and n-C 16 fatty acids in the surface sediments. These fatty acids then dominated the distribution patterns of almost all samples investigated.

Molecular composition of organic matter in the sediment of a mussel bee as an indicator of ecological variations

Surface sediments from a mussel bed (Mytilus edulis) and a transect into the adjacent sand flat of the Northwest German intertidal zone were analyzed for total organic carbon content and the molecular distributions of selected lipids. The mussel bed preferentially accumulates organic matter during phytoplankton blooms as faecal pellets and during macroalgae occurrence as detrital material, with the quantity depending on the epifaunistic structure and the population density. Lipid biomarkers (e.g., sterols) allow to distinguish between diatomaceous and macroalgal sources of organic matter. In late summer, these data appear to illustrate a dependence of the intensity of the diatom bloom on the extent of previous macroalgae occurrence. Molecular analysis ofPhaeogistis, mussel tissue and faeces from feeding experiments show that different life stages (single-cell, colonial) of the alga are reflected in the biomarker patterns of the corresponding faeces. Indicators of early diagenesis (e.g., A-ring saturated sterols) demonstrate that the anaerobic microbial hydrogenation of ingested sterols is less important than the same transformation occurring later in the sediment.KurzfassungOberflächensedimente aus einer Muschelbank (Mytilus edulis) und einem Transekt in das umliegende Sandwatt im nordwestdeutschen Wattengebiet wurden auf den Gesamtgehalt an organischem Kohlenstoff und die molekulare Zusammensetzung ausgewählter Lipide untersucht. Organisches Material wird in der Muschelbank in Abhängigkeit von der epifaunistischen Struktur und der Besiedlungsdichte vorwiegend während der Planktonblüten als Faeces und während des Auftretens von Makroalgen als Detritus angereichert. Mit Hilfe von Lipidbiomarkern kann zwischen organischem Material aus Diatomeen und solchem aus Makroalgen unterschieden werden. Gerade im späten Sommer scheint sich daraus eine Abhängigkeit des Ausmaßes der Phytoplankton-Herbstblüte von der Intensität des vorausgegangen Makroalgenauftretens ableiten zu lassen. Molekulare Untersuchungen anPhaeogistis, Muscheln und Faeces aus Fütterungsexperimenten zeigen, daß sich die verschiedenen Lebensstadien der Alge (Einzelzellen, Kolonien) in den Biomarkermustem der zugehörigen Faeces widerspiegeln. Mit molekularen Indikatoren frühdia-genetischer Prozesse (A-Ring-gesättigten Sterolen) läßt sich nachweisen, daß die anaerobe mikrobielle Hydrierung der filtrierten Algen im Verdauungssystem der Muscheln weniger ausgeprägt ist als die gleiche Umwandlung später im Sediment.

Alkylated phenol series in lacustrine black shales from the Nördlinger Ries, southern Germany

Several series of alkylated phenols were detected for the first time in the extractable bitumens of organic matter-rich sediments from the Nördlinger Ries (southern Germany). Most abundant and significant constituents comprise those with n-octadecyl, n-eicosanyl, phytanyl, and iso-pentadecyl and anteiso-pentadecyl substituents. The structures of these compounds are suggested from mass spectrometric and retention time data and coinjection with synthetic standards. Diagenetic alteration of phenolic algal lipids is suggested as a possible way to the formation of these compounds in the Nördlinger Ries sediments.

Effect of ice rafting on surface sediments in the Wadden Sea traced by organic geochemical methods

Ice rafting in the Lower Saxonian Wadden Sea in winter 1995/96 had a dramatic effect on surface sediments. Mussel beds ofMytilus edulis were destroyed and sediments redeposited. Organic material formerly biodeposited by mussels was found to have been shifted to a location almost one kilometer away. Evidence for this is taken from a change of the spatial organic carbon distribution in the study area and a comparison of molecular distribution profiles of fatty acids and sterols.KurzfassungDurch den Eiswinter 1996/97 wurden die Oberflächensedimente im Niedersächsischen Wattenmeer dramatisch in Mitleidenschaft gezogen. Eine Muschelbank vonMytilus edulis wurde zerstört, und die Sedimente wurden durch Eisschollen verfrachtet. Das organische Material der Biodeposite der früheren Muschelbank wurde in etwa einem Kilometer Entfernung wiedergefunden. Anhaltspunkte dafür lieferten die Veränderung der räumlichen Verteilung der organischen Kohlenstoffgehalte im Untersuchungsgebiet und die Verteilungsmuster von Fettsäuren und Sterolen.