Differentiating α-moganite, silanol and α-quartz by Raman spectroscopy.

The silica phases quartz, silanol and moganite are widely prevalent and consequential in industrial applications and natural science. However, methods for differentiating these important phases are few. Using Raman spectra simulated by density function and perturbation expansion after discretization theory, representative spectra could be obtained and the comingling of diagnostic Raman Bands for the three phases identified in samples. On this basis new methods to identify moganite in Raman spectra are proposed.

What about nitrogen? Using nitrogen as a carrier gas during the analysis of petroleum biomarkers by gas chromatography mass spectrometry.

Gas chromatography mass spectrometry (GC-MS) is a commonly used method for organic geochemistry for both academic research and applications such as petroleum analysis. Gas chromatography requires a carrier gas, which needs to be both volatile and stable and in most organic geochemical applications helium or hydrogen have been used, with helium predominating for gas chromatography mass spectrometry. Helium, however, is becoming an increasingly scarce resource and is not sustainable. Hydrogen is the most commonly considered alternative carrier gas to helium but has characteristics that in certain respects make its use less practical, foremost is that hydrogen is flammable and explosive. But as hydrogen is increasingly used as a fuel, higher demand may also make its use less desirable. Here we show that nitrogen can be used for the GC-MS analysis of fossil lipid biomarkers. Using nitrogen, chromatographic separation of isomers and homologues can be achieved, but sensitivity is orders of magnitude less than for helium. It is reasonable to use nitrogen as a carrier gas in applications where low levels of detection are not needed, such as the characterization of samples of crude oil or foodstuffs, or potentially as part of a gas-mixture seeking to reduce helium-demand but maintain a level of chromatographic separation sufficient to support proxy-based characterizations of petroleum.

Temperature limits to deep subseafloor life in the Nankai Trough subduction zone.

Microorganisms in marine subsurface sediments substantially contribute to global biomass. Sediments warmer than 40°C account for roughly half the marine sediment volume, but the processes mediated by microbial populations in these hard-to-access environments are poorly understood. We investigated microbial life in up to 1.2-kilometer-deep and up to 120°C hot sediments in the Nankai Trough subduction zone. Above 45°C, concentrations of vegetative cells drop two orders of magnitude and endospores become more than 6000 times more abundant than vegetative cells. Methane is biologically produced and oxidized until sediments reach 80° to 85°C. In 100° to 120°C sediments, isotopic evidence and increased cell concentrations demonstrate the activity of acetate-degrading hyperthermophiles. Above 45°C, populated zones alternate with zones up to 192 meters thick where microbes were undetectable.

Evidence in the Japan Sea of microdolomite mineralization within gas hydrate microbiomes.

Over the past 15 years, massive gas hydrate deposits have been studied extensively in Joetsu Basin, Japan Sea, where they are associated primarily with active gas chimney structures. Our research documents the discovery of spheroidal microdolomite aggregates found in association with other impurities inside of these massive gas hydrates. The microdolomites are often conjoined and show dark internal cores occasionally hosting saline fluid inclusions. Bacteroidetes sp. are concentrated on the inner rims of microdolomite grains, where they degrade complex petroleum-macromolecules present as an impurity within yellow methane hydrate. These oils show increasing biodegradation with depth which is consistent with the microbial activity of Bacteroidetes. Further investigation of these microdolomites and their contents can potentially yield insight into the dynamics and microbial ecology of other hydrate localities. If microdolomites are indeed found to be ubiquitous in both present and fossil hydrate settings, the materials preserved within may provide valuable insights into an unusual microhabitat which could have once fostered ancient life.

Identification, Geochemical Characterisation and Significance of Bitumen among the Grave Goods of the 7th Century Mound 1 Ship-Burial at Sutton Hoo (Suffolk, UK).

The 7th century ship-burial at Sutton Hoo is famous for the spectacular treasure discovered when it was first excavated in 1939. The finds include gold and garnet jewellery, silverware, coins and ceremonial armour of broad geographical provenance which make a vital contribution to understanding the political landscape of early medieval Northern Europe. Fragments of black organic material found scattered within the burial were originally identified as 'Stockholm Tar' and linked to waterproofing and maintenance of the ship. Here we present new scientific analyses undertaken to re-evaluate the nature and origin of these materials, leading to the identification of a previously unrecognised prestige material among the treasure: bitumen from the Middle East. Whether the bitumen was gifted as diplomatic gesture or acquired through trading links, its presence in the burial attests to the far-reaching network within which the elite of the region operated at this time. If the bitumen was worked into objects, either alone or in composite with other materials, then their significance within the burial would certainly have been strongly linked to their form or purpose. But the novelty of the material itself may have added to the exotic appeal. Archaeological finds of bitumen from this and earlier periods in Britain are extremely rare, despite the abundance of natural sources of bitumen within Great Britain. This find provides the first material evidence indicating that the extensively exploited Middle Eastern bitumen sources were traded northward beyond the Mediterranean to reach northern Europe and the British Isles.

Recreating mineralogical petrographic heterogeneity within microfluidic chips: assembly, examples, and applications.

To date, the visualisation of flow through porous media assembled in microfluidic chips was confined to mineralogically homogenous systems. Here we present a key evolution in the method that permits the investigation of mineralogically realistic rock analogues.

Survival of organic materials in hypervelocity impacts of ice on sand, ice, and water in the laboratory.

The survival of organic molecules in shock impact events has been investigated in the laboratory. A frozen mixture of anthracene and stearic acid, solvated in dimethylsulfoxide (DMSO), was fired in a two-stage light gas gun at speeds of ~2 and ~4 km s(-1) at targets that included water ice, water, and sand. This involved shock pressures in the range of 2-12 GPa. It was found that the projectile materials were present in elevated quantities in the targets after impact and in some cases in the crater ejecta as well. For DMSO impacting water at 1.9 km s(-1) and 45° incidence, we quantify the surviving fraction after impact as 0.44±0.05. This demonstrates successful transfer of organic compounds from projectile to target in high-speed impacts. The range of impact speeds used covers that involved in impacts of terrestrial meteorites on the Moon, as well as impacts in the outer Solar System on icy bodies such as Pluto. The results provide laboratory evidence that suggests that exogenous delivery of complex organic molecules from icy impactors is a viable source of such material on target bodies.

The use of surface-enhanced Raman scattering for detecting molecular evidence of life in rocks, sediments, and sedimentary deposits.

Raman spectroscopy is a versatile analytical technique capable of characterizing the composition of both inorganic and organic materials. Consequently, it is frequently suggested as a payload on many planetary landers. Only approximately 1 in every 10(6) photons are Raman scattered; therefore, the detection of trace quantities of an analyte dispersed in a sample matrix can be much harder to achieve. To overcome this, surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) both provide greatly enhanced signals (enhancements between 10(5) and 10(9)) through the analyte's interaction with the locally generated surface plasmons, which occur at a "roughened" or nanostructured metallic surface (e.g., Cu, Au, and Ag). Both SERS and SERRS may therefore provide a viable technique for trace analysis of samples. In this paper, we describe the development of SERS assays for analyzing trace amounts of compounds present in the solvent extracts of sedimentary deposits. These assays were used to detect biological pigments present in an Arctic microoasis (a small locale of elevated biological productivity) and its detrital regolith, characterize the pigmentation of microbial mats around hydrothermal springs, and detect fossil organic matter in hydrothermal deposits. These field study examples demonstrate that SERS technology is sufficiently mature to be applied to many astrobiological analog studies on Earth. Many current and proposed imaging systems intended for remote deployment already posses the instrumental components needed for SERS. The addition of wet chemistry sample processing facilities to these instruments could yield field-deployable analytical instruments with a broadened analytical window for detecting organic compounds with a biological or geological origin.

Benchmarking methods of enhanced heavy oil recovery using a microscaled bead-pack.

A microscaled bead-pack is capable of simulating two-phase fractional flow within porous media and can be applied to simulating interactions between fluids and geological materials under dynamic conditions within the laboratory.

Signal enhancement of surface enhanced Raman scattering and surface enhanced resonance Raman scattering using in situ colloidal synthesis in microfluidics.

We demonstrate the enhanced analytical sensitivity of both surface enhanced Raman scattering (SERS) and surface enhanced resonance Raman scattering (SERRS) responses, resulting from the in situ synthesis of silver colloid in a microfluidic flow structure, where both mixing and optical interrogation were integrated on-chip. The chip-based sensor was characterized with a model Raman active label, rhodamine-6G (R6G), and had a limit of detection (LOD) of ca. 50 fM (equivalent to single molecule detection). The device was also used for the determination of the natural pigment, scytonemin, from cyanobacteria (as an analogue for extraterrestrial life existing in extreme environments). The observed LOD of approximately 10 pM (ca. <400 molecules) demonstrated the analytical advantages of working with freshly synthesized colloid in such a flow system. In both cases, sensitivities were between 1 and 2 orders of magnitude greater in the microfluidic system than those measured using the same experimental parameters, with colloid synthesized off-chip, under quiescent conditions.

Determination of the asphaltene and carboxylic acid content of a heavy oil using a microfluidic device.

Heavy oil utilisation is set to increase over the coming decades as reserves of conventional oil decline. Heavy oil differs from conventional oil in containing relatively large quantities of asphaltene and carboxylic acids. The proportions of these compounds greatly influence how oil behaves during production and its utilisation as a fuel or feedstock. We report the development of a microfluidic technique, based on a H-cell, that can extract the carboxylic acid components of an oil and assess its asphaltene content. Ultimately this technology could yield a field-deployable device capable of performing measurements that facilitate improved resource management at the point of resource-extraction.

Surface-enhanced Raman signatures of pigmentation of cyanobacteria from within geological samples in a spectroscopic-microfluidic flow cell.

A simple surface-enhanced Raman spectroscopy (SERS) microflow cell was developed to investigate distributions of scytonemin pigment within cyanobacteria from samples of rock collected from an arctic desert that contained endolithic cyanobacteria. The assay, which has future potential use in a variety of applications, including astrobiology and analysis of microorganisms in remote environments, involved studying SERS spectra of bacteria from within geological samples. By using a dispersed colloidal substrate in the microfluidic device, surface enhancement of the order >10(5) was obtained for the determination of the pigment in the microorganisms when compared to the native Raman spectra. The SERS assay, which had a nM sensitivity for scytonemin, showed that the concentration of pigment was highest in samples that had experienced the highest stress environments, as a result of high doses of UV irradiation.

Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea.

The disappearance of iron formations from the geological record approximately 1.8 billion years (Gyr) ago was the consequence of rising oxygen levels in the atmosphere starting 2.45-2.32 Gyr ago. It marks the end of a 2.5-Gyr period dominated by anoxic and iron-rich deep oceans. However, despite rising oxygen levels and a concomitant increase in marine sulphate concentration, related to enhanced sulphide oxidation during continental weathering, the chemistry of the oceans in the following mid-Proterozoic interval (approximately 1.8-0.8 Gyr ago) probably did not yet resemble our oxygen-rich modern oceans. Recent data indicate that marine oxygen and sulphate concentrations may have remained well below current levels during this period, with one model indicating that anoxic and sulphidic marine basins were widespread, and perhaps even globally distributed. Here we present hydrocarbon biomarkers (molecular fossils) from a 1.64-Gyr-old basin in northern Australia, revealing the ecological structure of mid-Proterozoic marine communities. The biomarkers signify a marine basin with anoxic, sulphidic, sulphate-poor and permanently stratified deep waters, hostile to eukaryotic algae. Phototrophic purple sulphur bacteria (Chromatiaceae) were detected in the geological record based on the new carotenoid biomarker okenane, and they seem to have co-existed with communities of green sulphur bacteria (Chlorobiaceae). Collectively, the biomarkers support mounting evidence for a long-lasting Proterozoic world in which oxygen levels remained well below modern levels.