Transfer of organic carbon through marine water columns to sediments – insights from stable and radiocarbon isotopes of lipid biomarkers

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 11 (2014): 6895-6914, doi:10.5194/bg-11-6895-2014.Compound-specific 13C and 14C compositions of diverse lipid biomarkers (fatty acids, alkenones, hydrocarbons, sterols and fatty alcohols) were measured in sinking particulate matter collected in sediment traps and from underlying surface sediments in the Black Sea, the Arabian Sea and the Ross Sea. The goal was to develop a multiparameter approach to constrain relative inputs of organic carbon (OC) from marine biomass, terrigenous vascular-plant and relict-kerogen sources. Using an isotope mass balance, we calculate that marine biomass in sediment trap material from the Black Sea and Arabian Sea accounted for 66–100% of OC, with lower terrigenous (3–8%) and relict (4–16%) contributions. Marine biomass in sediments constituted lower proportions of OC (66–90%), with consequentially higher proportions of terrigenous and relict carbon (3–17 and 7–13%, respectively). Ross Sea data were insufficient to allow similar mass balance calculations. These results suggest that, whereas particulate organic carbon is overwhelmingly marine in origin, pre-aged allochthonous terrigenous and relict OC become proportionally more important in sediments, consistent with pre-aged OC being better preserved during vertical transport to and burial at the seafloor than the upper-ocean-derived marine OC.Grants OCE-9310364 and OCE-9911678 from the US National Science Foundation (NSF) and the NSF Cooperative Agreement for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-0753487 and OCE-123966) supported this research. S. G. Wakeham acknowledges the Hanse Wissenschaftskolleg (Hanse Institute for Advanced Studies), Delmenhorst, Germany, for a fellowship that supported the writing of this manuscript

The medicinal and pharmacological screening of wheatgrass juice (Triticum aestivum L.): an investigation into chlorophyll content and antimicrobial activity

Plant products are of increasing interest in the search for new drugs and medicines in the treatment of disease; and the discovery of new alternatives to existing antibiotics is an important area of this research due to pathogen resistance. One example of a plant product currently under pharmacological investigation is wheatgrass juice; a dietary supplement derived from Triticum aestivum L. There is both anecdotal and scientific evidence to suggest that the medicinal efficacy of this plant may be due to its high chlorophyll concentrations. In this study chlorophyll fresh weight was determined in mg/100g for organic field grown wheatgrass juice and samples grown hydroponically in a glasshouse. Broccoli and Kale samples were included for comparison. Fresh undiluted wheatgrass juice was then screened against bacteria: Escherichia coli NCTC 10418; Staphylococcus aureus NCTC 6571 and Streptococcus mutans NCIMB 702062, using the agar well diffusion method. Acetone extracts were also tested. Results showed field grown samples had the highest chlorophyll content, not significantly different to Kale (p =0.834) and significantly higher than Broccoli (p <0.001). Hydroponically grown samples contained 73.4% less chlorophyll than field grown wheatgrass (p <0.001). None of the extracts tested displayed any kind of antimicrobial activity against selected pathogens. There is growing evidence that dietary chlorophyll may have cancer preventing properties by limiting the bio-availability of carcinogens, and wheatgrass juice appears to be a good source of this phytopigment. Although this study reported no antimicrobial activity, previous studies have reported conflicting results, indicating further investigation is required in this area

Competing magnetic orders in the superconducting state of Nd-doped CeRhIn5_{5} under pressure

Applied pressure drives the heavy-fermion antiferromagnet CeRhIn$_{5}$ towards a quantum critical point that becomes hidden by a dome of unconventional superconductivity. Magnetic fields suppress this superconducting dome, unveiling the quantum phase transition of local character. Here, we show that $5\%$ magnetic substitution at the Ce site in CeRhIn$_{5}$, either by Nd or Gd, induces a zero-field magnetic instability inside the superconducting state. This magnetic state not only should have a different ordering vector than the high-field local-moment magnetic state, but it also competes with the latter, suggesting that a spin-density-wave phase is stabilized in zero field by Nd and Gd impurities - similarly to the case of Ce$_{0.95}$Nd$_{0.05}$CoIn$_{5}$. Supported by model calculations, we attribute this spin-density wave instability to a magnetic-impurity driven condensation of the spin excitons that form inside the unconventional superconducting state

Analysis of hybrid separation schemes for levulinic acid separation by process intensification and assessment of thermophysical properties impact

From the time levulinic acid was listed as one of the top-12 building blocks for the sugars-high value compounds conversion, the interest in this compound increased. As part of its possible production route, the definition of viable separation schemes appears of paramount importance in the overall development of levulinic acid exploitation. Hybrid sequences where liquid-liquid extraction is followed by distillation were considered proving how the direct and direct-indirect separation schemes appeared to be the best alternatives in terms of total annual cost and environmental impact. These alternatives were further analyzed to improve their design by complementing the process simulator database with thermophysical experimental values. After obtaining a reliable design for the hybrid direct and direct-indirect configurations used as benchmarks, two intensified al-ternatives were generated. The first intensified configuration is classified as thermodynamically equivalent sequence, while the second one includes a divided wall column. For both, it was achieved a reduction of the total annual cost of 11% without any penalty for the environmental impact compared to the reference case

Viscosity measurements on Ionic liquids : a cautionary tale

The vibrating-wire viscometer has proven to be an exceedingly effective means of determining the viscosity of liquids over a wide range of temperature and pressure. The instrument has a long history but a variety of technological and theoretical developments over a number of years have improved its precision and most recently have enabled absolute measurements of high accuracy. However, the nature of the electrical measurements required for the technique has inhibited its widespread use for electrically conducting liquids so that there have been only a limited number of measurements. In the particular context of ionic liquids, which have themselves attracted considerable attention, this is unfortunate because it has meant that one primary measurement technique has seldom been employed for studies of their viscosity. In the last 2 years systematic efforts have been made to explore the applicability of the vibrating-wire technique by examining a number of liquids of increasing electrical conductivity. These extensions have been successful. However, in the process we have had cause to review previous studies of the viscosity and density of the same liquids at moderate temperatures and pressures and significant evidence has been accumulated to cause concern about the application of a range of viscometric techniques to these particular fluids. Because the situation is reminiscent of that encountered for a new set of environmentally friendly refrigerants at the end of the last decade, in this paper the experimental methods employed with these liquids have been reviewed which leads to recommendations for the handling of these materials that may have consequences beyond viscometric measurements. In the process new viscosity and density data for 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [C6mim][NTf2], 1-ethyl-3-methylimidazolium ethyl sulfate [C2mim][EtSO4], and 1-ethyl-3-methylpyridinium ethyl sulfate [C2mpy][EtSO4] have been obtained