Composition of organic matter in suspended matter and bottom sediments of the southeastern Baltic Sea

Data on contents and compositions of hydrocarbons (HCs)-aliphatic (AHCs) and polycyclic aromatic (PAHs) are provided in comparison with contents of total organic carbon (Corg), lipids in suspended matter, and Corg in bottom sediments. Particular attention is paid to distribution of HCs in the area of the Kravtsov oil field. It is established that concentrations of AHCs in water are governed by concentrations of suspended matter and elevated AHC concentrations are confined to coastal areas. In the area of D-6 platform sandy bottom sediments are notable for great variability of HC concentrations, both laterally and from year to year. In summer of 2010 average content of AHCs was 40 ppm (19% of Corg) and that of PAHs was 0.023 ppm. Natural seepage from sediment mass is considered to be a source of HCs along with oil contamination.

Correlation of Kauzman temperature with odd-even effect in n-alkanes

A unique correlation has been established between Kauzmann temperature (Tk1) and the odd–even effect in n‐alkanes. The derived new parameter, i.e., Tm/Tk1 obtained from entropy conservation at Tk1, when plotted against chain length, provides a much sharper odd–even contrast than entropy of fusion plot reported earlier. © 1996 American Institute of Physics.

Biofilm Eradication Kinetics of the Ultrashort Lipopeptide C12-OOWW-NH2 Utilizing a Modified MBEC Assay™

In this study, we report the antimicrobial planktonic and biofilm kill kinetics of ultrashort cationic lipopeptides previously demonstrated by our group to have a minimum biofilm eradication concentration (MBEC) in the microgram per mL (μg/mL) range against clinically relevant biofilm-forming micro-organisms. We compare the rate of kill for the most potent of these lipopeptides, dodecanoic (lauric) acid-conjugated C₁₂-Orn-Orn-Trp-Trp-NH₂ against the tetrapeptide amide H-Orn-Orn-Trp-Trp-NH₂ motif and the amphibian peptide Maximin-4 via a modification of the MBEC Assay™ for Physiology & Genetics (P&G). Improved antimicrobial activity is achieved upon N-terminal lipidation of the tetrapeptide amide. Increased antimicrobial potency was demonstrated against both planktonic and biofilm forms of Gram-positive micro-organisms. We hypothesize rapid kill to be achieved by targeting of microbial membranes. Complete kill against established 24-h Gram-positive biofilms occurred within 4 h of exposure to C₁₂-OOWW-NH₂ at MBEC values [methicillin-resistant Staphylococcus epidermidis (ATCC 35984): 15.63 μg/mL] close to the values for the planktonic minimum inhibitory concentration (MIC) [methicillin-resistant Staphylococcus epidermidis (ATCC 35984): 1.95 μg/mL]. Such rapid kill, especially against sessile biofilm forms, is indicative of a reduction in the likelihood of resistant strains developing with the potential for quicker resolution of pathogenic infection. Ultrashort antimicrobial lipopeptides have high potential as antimicrobial therapy.

Calculating Flash Point Numbers from Molecular Structure: An Improved Method for Predicting the Flash Points of Acyclic Alkanes

We report a novel method for calculating flash points of acyclic alkanes from flash point numbers, N(FP), which can be calculated from experimental or calculated boiling point numbers (Y(BP)) with the equation N(FP) = 1.020Y(BP) - 1.083 Flash points (FP) are then determined from the relationship FP(K) = 23.369N(FP)(2/3) + 20.010N(FP)(1/3) + 31.901 For it data set of 102 linear and branched alkanes, the correlation of literature and predicted flash points has R(2) = 0.985 and an average absolute deviation of 3.38 K. N(FP) values can also be estimated directly from molecular structure to produce an even closer correspondence of literature and predicted FP values. Furthermore, N(FP) values provide a new method to evaluate the reliability of literature flash point data.

Sedimentary lipids and palynomorphs of sediment core ABC26 from the Eastern Mediterranean

Selective degradation of organic matter in sediments is important for reconstructing past environments and understanding the carbon cycle. Here, we report on compositional changes between and within lipid classes and kerogen types (represented by palynomorph groups) in relation to the organic matter flux to the sea floor and oxidation state of the sediments since the early Holocene for central Eastern Mediterranean site ABC26. This includes the initially oxic but nowadays anoxic presapropelic interval, the still unoxidised lower part of the organic rich S1 sapropel, its postdepositionally oxidised and nowadays organic-poor upper part as well as the overlying postsapropelic sediments which have always been oxic. A general ~ 2.3 times increase in terrestrial and marine input during sapropel formation is estimated on the basis of the total organic carbon (TOC), pollen, spore, dinoflagellate cyst, n-alkane, n-alkanol and n-alkanoic acid concentration changes in the unoxidised part of the sapropel. The long-chain alkenones, 1,15 diols and keto-ols, loliolides and sterols indicate that some plankton groups, notably dinoflagellates, may have increased much more. Apart from the terrestrial and surface water contributions to the sedimentary organic matter, anomalous distributions and preservation of some C23-C27 alkanes, alkanols and alkanoic acids have been observed, which are interpreted as a contribution by organisms living in situ. Comparison of the unoxidised S1 sapropel with the overlying oxidised sapropel and the organic matter concentration profiles in the oxidised postsapropelic sediments demonstrates strong and highly selective aerobic degradation of lipids and palynomorphs. There seems to be a fundamental difference in degradation kinetics between lipids and pollen which may be possibly related with the absence of sorptive preservation as a protective mechanism for palynomorph degradation. The n-alkanes, Impagidinium, and Nematosphaeropsis are clearly more resistant than TOC. The n-alkanols and n-carboxylic acids are about equally resistant whereas the pollen, all other dinoflagellate cysts and other lipids appear to degrade considerably faster, which questions the practice of normalising to TOC without taking diagenesis into account. Selective degradation also modifies the relative distributions within lipid classes, whereby the longer-chain alkanes, alcohols and fatty acids disappear faster than their shorter-chain equivalents. Accordingly, interpretation of lipid and palynomorph assemblages in terms of pre- or syndepositional environmental change should be done carefully when proper knowledge of the postdepositional preservation history is absent. Two lipid-based preservation proxies are tested the diol-keto-ol oxidation index based on the 1,15C30 diol and keto-ols (DOXI) and the alcohol preservation index (API) whereby the former seems to be the most promising.

Bitumen and n-alkanes in organic matter from sedimentary rocks sampled in DSDP Holes 47-397A and 47-398

A study of samples from DSDP Leg 47 shows that transformation of organic matter in deep sea sediments is completly analogous to evolution of organic matter in sedimentary sequences on continents and depends on the same factors. Crucial among these factors are: genesis of organic matter, nature of its diagenetic changes, and current stage of catagenesis.

Biomarker records of DSDP Hole 24-231 and terrestrial sediments

ntegrated terrestrial and marine records of northeast African vegetation are needed to provide long high resolution records of environmental variability with established links to specific terrestrial environments. In this study, we compare records of terrestrial vegetation preserved in marine sediments in the Gulf of Aden [Deep Sea Drilling Project (DSDP) Site 231] and an outcrop of lacustrine sediments in the Turkana Basin, Kenya, part of the East African Rift System. We analyzed higher plant biomarkers in sediments from both deposits of known equivalent age, corresponding to a ca. 50-100 ka humid interval prior to the b-Tulu Bor eruption ca. 3.40 Ma, when the Lokochot Lake occupied part of the Turkana Basin. Molecular abundance distributions indicate that long chain n-alkanoic acids in marine sediments are the most reliable proxy for terrestrial vegetation (Carbon Preference Index, CPI = 4.5), with more cautious interpretation needed for n-alkanes and lacustrine archives. Marine sediments record carbon isotopic variability in terrestrial biomarkers of 2-3 per mil, roughly equivalent to 20% variability in the C3/C4 vegetation contribution. The proportion of C4 vegetation apparently increased at times of low terrigenous dust input. Terrestrial sediments reveal much larger (2-10 per mil) shifts in n-alkanoic acid delta13C values. However, molecular abundance and isotopic composition suggest that microbial sources may also contribute fatty acids, contaminating the lacustrine sedimentary record of terrestrial vegetation.

n-Alkane, fatty acid and hopanoic acid concentrations of ODP Site 190-1178 samples

Ocean Drilling Program (ODP) Leg 190 was programmed to investigate deformational, diagenetic, and hydrologic processes and their interactions in the Nankai Trough accretionary prism. Site 1178 is the northernmost site in the Muroto Transect. Slope sediments and the underlying landward-dipping reflector zone were successfully cored. Temperature measurements and Cl concentrations in pore water indirectly indicate the presence of gas hydrate between 120 and 400 meters below seafloor (mbsf) at Site 1178, with the highest concentrations between 150 and 200 mbsf (Shipboard Scientific Party, 2001, doi:10.2973/odp.proc.ir.190.109.2001). Sedimentary structures show a broad range of deformation structures rich in fractures, suggesting active fluid circulation in the Nankai Trough prism. One of the objectives of Leg 190 was to clarify the interplay of various fundamental processes taking place in the Nankai Trough accretionary prism. Bacteria or prokaryotes in deep subsurface sediment play an important role for material transformation and circulation in an accretionary prism. Significant amounts of bacteria are detected in many of the samples examined (Shipboard Scientific Party, 2001, doi:10.2973/odp.proc.ir.190.109.2001). The type of organic matter in sediments is an important factor related to bacterial activity. To assist investigations on material circulation in deep subsurface sediments, the samples from Site 1178 were analyzed for geolipids (extractable organic matter). The basic data set is preliminarily compiled in the present report to show the types of organic matter and their concentrations in sediments from Site 1178.

Sterol, n-alcohol and n-alkane composition of living fen plants

In groundwater-fed fen peatlands, the surface biomass decays rapidly and, as a result, highly humified peat is formed. A high degree of humification constrains palaeoecological studies because reliable identification of plant remains is hampered. Organic geochemistry techniques as a means of identifying historical plant communities have been successfully applied tobog peat. The method has also been applied to fen peat, but without reference to the composition of fen plants. We have applied selected organic geochemistry methods to determine the composition of the neutral lipid fractions from 12 living fen plants, to investigate the potential for the distributions to characterize and separate different fen plants and plant groups. Our results show correspondence with previous studies, e.g. C23 and C25n-alkanes dominating Sphagnum spp. and C27 to C31 alkanes dominating vascular plants. However, we also found similarities in n-alkane distributions between Sphagnum spp. and the below ground parts of some vascular plants. We tested the efficiency of different n-alkane ratios to separate species and plant groups. The ratios used for bog studies (e.g. n-C23/n-C25 and n-C23/n-C29) did not work as consistently for fen plants. Some differences in sterol distribution were found between vascular plants and mosses; in general vascular plants had a higher concentration of sterols. When distributions of n-alkanes, n-alkane ratios and sterols were all included as variables, redundancy analysis (RDA) separated different plant groups into their own clusters. Our results imply that the pattern for bog biomarkers cannot directly be applied to fen environments. Nevertheless, they encourage further testing to determine whether or not the identification of plant groups, plants or plant parts from highly humified peat is possible by applying fen species-specific biomarker proxies.