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The search for in situ organic matter on Mars involves encounters with minerals and requires an understanding of their influence on lander and rover experiments. Inorganic host materials can be helpful by aiding the preservation of organic compounds or unhelpful by causing the destruction of organic matter during thermal extraction steps. Perchlorates are recognized as confounding minerals for thermal degradation studies. On heating, perchlorates can decompose to produce oxygen, which then oxidizes organic matter. Other common minerals on Mars, such as sulfates, may also produce oxygen upon thermal decay, presenting an additional complication. Different sulfate species decompose within a large range of temperatures. We performed a series of experiments on a sample containing the ferric sulfate jarosite. The sulfate ions within jarosite break down from 500°C. Carbon dioxide detected during heating of the sample was attributed to oxidation of organic matter. A laboratory standard of ferric sulfate hydrate released sulfur dioxide from 550°C, and an oxygen peak was detected in the products. Calcium sulfate did not decompose below 1000°C. Oxygen released from sulfate minerals may have already affected organic compound detection during in situ thermal experiments on Mars missions. A combination of preliminary mineralogical analyses and suitably selected pyrolysis temperatures may increase future success in the search for past or present life on Mars. Key Words: Mars—Life detection—Geochemistry—Organic matter—Jarosite. Astrobiology 15, 247–258.

The majority of global petroleum is in the form of highly viscous heavy oil. Traditionally heavy oil in sands at shallow depths is accessed by large scale mining activities. Recently steam has been used to allow heavy oil extraction with greatly reduced surface disturbance. However, in situ thermal recovery processes can generate hydrogen sulphide, high levels of which are toxic to humans and corrosive to equipment. Avoiding hydrogen sulphide production is the best possible mitigation strategy. Here we use laboratory aquathermolysis to reproduce conditions that may be experienced during thermal extraction. The results indicate that hydrogen sulphide generation occurs within a specific temperature and pressure window and corresponds to chemical and physical changes in the oil. Asphaltenes are identified as the major source of sulphur. Our findings reveal that for high sulphur heavy oils, the generation of hydrogen sulphide during steam assisted thermal recovery is minimal if temperature and pressure are maintained within specific criteria. This strict pressure and temperature dependence of hydrogen sulphide release can allow access to the world's most voluminous oil deposits without generating excessive amounts of this unwanted gas product.

The organic record of Earth older than ∼3.8 Ga has been effectively erased. Some insight is provided to us by meteorites as well as remote and direct observations of asteroids and comets left over from the formation of the Solar System. These primitive objects provide a record of early chemical evolution and a sample of material that has been delivered to Earth's surface throughout the past 4.5 billion years. Yet an effective chronicle of organic evolution on all Solar System objects, including that on planetary surfaces, is more difficult to find. Fortunately, early Earth would not have been the only recipient of organic matter–containing objects in the early Solar System. For example, a recently proposed model suggests the possibility that volatiles, including organic material, remain archived in buried paleoregolith deposits intercalated with lava flows on the Moon. Where asteroids and comets allow the study of processes before planet formation, the lunar record could extend that chronicle to early biological evolution on the planets. In this study, we use selected free and polymeric organic materials to assess the hypothesis that organic matter can survive the effects of heating in the lunar regolith by overlying lava flows. Results indicate that the presence of lunar regolith simulant appears to promote polymerization and, therefore, preservation of organic matter. Once polymerized, the mineral-hosted newly formed organic network is relatively protected from further thermal degradation. Our findings reveal the thermal conditions under which preservation of organic matter on the Moon is viable. Key Words: Moon—Regolith—Organic preservation—Biomarkers. Astrobiology 15, 154–168.

We have undertaken a comprehensive study of carbon and nitrogen elemental abundances and isotopic compositions of bulk carbonaceous chondrites. A strategy of multiple analyses has enabled the investigation of hitherto unconstrained small-scale heterogeneities. No systematic differences are observed between meteorite falls and finds, suggesting that terrestrial processing has a minimal effect on bulk carbon and nitrogen chemistry. The changes in elemental abundance and isotopic composition over the petrologic range may reflect variations in primary accreted materials, but strong evidence exists of the alteration of components during secondary thermal and aqueous processing. These changes are reflected within the CM2 and CO3 groups and follow the published alteration scales for those groups. The nitrogen isotope system appears to be controlled by an organic host, which loses a 15N-rich component with progressive alteration. This study recommends caution, however, over the use of bulk carbon and nitrogen information for classification purposes; variance in relative abundance of different components in carbonaceous chondrites is significant and reflects intrameteorite heterogeneities.

This study describes the reduction of functionalised model compounds to their corresponding hydrocarbons by catalytic hydropyrolysis to provide information on the release of biomarkers from kerogens and asphaltenes covalently bound through the functional groups investigated. Five model compounds were investigated, the n -C 18 carboxylic acids, stearic and oleic acids; the C 24 steroidal acid, 5β-cholanic acid; and the saturated and unsaturated C 27 sterols, 5α-cholestanol and cholesterol. The yield and distribution of the hydrocarbons generated were assessed for the model compounds adsorbed to silica and carbon substrates, and unsupported on a bed of catalyst. The n -C 18 acids are shown to be reduced to the n -C 18 alkane, with a selectivity of >95% for stearic acid, although due to its unsaturated structure, oleic acid is prone to cracking, with shorter chained n -alkanes also being formed. The conversion of these compounds, adsorbed to either silica or carbon is relatively low, even at hydropyrolysis temperatures significantly above their boiling point, suggesting that interactions between the acids and substrate leading to the formation of stable entities (Si–O–C linkages in the case of silica) significantly retard volatilisation. The yield can be increased by placing the compounds directly onto a bed of catalyst, but for low boiling compounds such as stearic acid this can result in volatilisation and cracking at temperatures below that of the activation point of the catalyst. This method produced improved yields of >95% pure product for higher boiling compounds such as 5β-cholanic acid. The presence of the functional group attached to the ring system of compounds such as 5α-cholestanol does not diminish the selectivity of the technique. The double bond in cholesterol resulted in more incomplete hydrogenation with sterenes being generated, and in addition to 5α and 5β-cholestane, diasteranes were also generated via migration of the double bond.

Antarctic subglacial lakes have, over the past few years, been hypothesised to house unique forms of life and hold detailed sedimentary records of past climate change. Testing this hypothesis requires in situ examinations. The direct measurement of subglacial lakes has been considered ever since the largest and best-known lake, named Lake Vostok, was identified as having a deep water-column. The Subglacial Antarctic Lake Environments (SALE) programme, set up by the Scientific Committee on Antarctic Research (SCAR) to oversee subglacial lakes research, state that prior exploration of smaller lakes would be a “prudent way forward”. Over 145 subglacial lakes are known to exist in Antarctica, but one lake in West Antarctica, officially named Ellsworth Subglacial Lake (referred to hereafter as Lake Ellsworth), stands out as a candidate for early exploration. A consortium of over 20 scientists from seven countries and 14 institutions has been assembled to plan the exploration of Lake Ellsworth. An eight-year programme is envisaged: 3 years for a geophysical survey, 2 years for equipment development and testing, 1 year for field planning and operation, and 2 years for sample analysis and data interpretation. The science experiment is simple in concept but complex in execution. Lake Ellsworth will be accessed using hot water drilling. Once lake access is achieved, a probe will be lowered down the borehole and into the lake. The probe will contain a series of instruments to measure biological, chemical and physical characteristics of the lake water and sediments, and will utilise a tether to the ice surface through which power, communication and data will be transmitted. The probe will pass through the water column to the lake floor. The probe will then be pulled up and out of the lake, measuring its environment continually as this is done. Once at the ice surface, any water samples collected will be taken from the probe for laboratory analysis (to take place over subsequent years). The duration of the science mission, from deployment of the probe to its retrieval, is likely to take between 24 and 36 h. Measurements to be taken by the probe will provide data about the following: depth, pressure, conductivity and temperature; pH levels; biomolecules (using life marker chips); anions (using a chemical analyzer); visualisation of the environment (using cameras and light sources); dissolved gases (using chromatography); and morphology of the lake floor and sediment structures (using sonar). After the probe has been retrieved, a sediment corer may be dropped into the lake to recover material from the lake floor. Finally, if time permits, a thermistor string may be left in the lake water to take time-dependent measurements of the lake’s water column over subsequent years. Given that the comprehensive geophysical survey of the lake will take place in two seasons during 2007–2009, a two-year instrument and logistic development phase from 2008 (after the lake’s bathymetry has been assessed) makes it possible that the exploration of Lake Ellsworth could take place at the beginning of the next decade.

The CR group of carbonaceous chondrites may represent some of the most primitive extraterrestrial materials available for analysis. However, in contrast to other chondrite groups, the CR organic fraction is poorly characterized. The carbonaceous chondrite literature shows that relatively anhydrous thermal processing results in a condensed, poorly alkylated, O-poor macromolecular material, while for aqueous processing the converse is true. Such characteristics can be used to discern the alteration histories of the carbonaceous chondrites. We have performed bulk elemental and isotopic analysis and flash pyrolysis on four CR chondrites (Renazzo, Al Rais, Elephant Moraine [EET] 87770, and Yamato [Y-] 790112) to determine the nature of their organic component. Renazzo, Al Rais, and Y-790112 release qualitatively similar pyrolysis products, although there are some variations. Al Rais' macromolecular structure contains substantially higher relative abundances of alkylated and oxidized species and relatively lighter ?15N, suggesting that it has endured more extensive aqueous processing than the other CR chondrites. Renazzo appears relatively unprocessed, with a low degree of alkylation, a lack of detectable nitrogen-bearing components, and low methylnaphthalene ratio. EET 87770's low abundance of alkylated species suggests its macromolecular structure may be relatively condensed, with condensation potentially assisted by a period of mild thermal alteration.

Aqueous and thermal processing of primordial materials occurred prior to and during planet formation in the early solar system. A record of how solid materials were altered at this time is present in the carbonaceous chondrites, which are naturally delivered fragments of primitive asteroids. It has been proposed that some materials, such as the clasts termed “dark inclusions” found in type III chondrites, suggest a sequence of aqueous and thermal events. Lithium isotopes (6Li and 7Li) can reveal the role of liquid water in dark inclusion history. During aqueous alteration, 7Li passes preferentially into solution leaving 6Li behind in the solid phase and, consequently, any relatively extended periods of interaction with 7Li-rich fluids would have left the dark inclusions enriched in the heavier isotope when compared to the meteorite as a whole. Our analyses of lithium isotopes in Allende and its dark inclusions reveal marked isotopic homogeneity and no evidence of greater levels of aqueous alteration in dark inclusion history.

Ionising radiation is an energy source capable of generating and altering complex organic matter. A full understanding of the radiolytic formation and evolution of organic matter is essential to appreciate the budget of organic chemicals that exist in cometary and interstellar ices, carbonaceous meteorites, and to understand the results of analyses of irradiated extraterrestrial organic matter, such as that in cometary nuclei. The effects of ionising radiation on a set of 10 naturally occurring, terrestrial organic assemblages have been revealed by pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), carbon isotopic analysis, and stepped combustion-isotope ratio mass spectrometry (SC-IRMS). Progressive radiolytic alteration of biogenic complex–hydrocarbon mixtures induces a decrease in the average size and extent of alkylation of polyaromatic hydrocarbons (PAH) and an increase in the abundance of oxygen-containing compounds, as indicated by Py–GC–MS, and an enrichment in 13C. These changes are attributed to reactions with free radicals, produced by ionising radiation. In contrast, the progressive radiolytic alteration of bitumens proposed to have derived from the radiolytic polymerisation of methane into an organic solid produces, upon pyrolysis, PAH of increasing average size and degree of alkylation. This, the opposite of the trend observed in the irradiated complex–hydrocarbons mixtures, cannot be explained in terms of the radiolytic alteration of a pre-existing array of complex organic molecules. Instead, it suggests the gradual construction of PAH from smaller molecules, supporting the hypothesis of a methane origin. Radiolytic alteration is also associated with a previously unrecognised increase in the mean combustion temperature of organic matter. This leads to predictions regarding the combustion characteristics of the irradiated organic matter present on cometary nuclei. A full understanding of the relationship between the combustion characteristics of organic polymers, radiation dose and the atomic H/C ratio should lead to the better design and implementation of in situ extraterrestrial sample analysis hardware and aid the interpretation of data from such missions. This study establishes predictable organic chemical responses of organic matter, upon exposure to ionising radiation. Our results support proposals that extraterrestrial PAH may be formed by the cosmic irradiation of simple hydrocarbons in interstellar ices. Our data may also be relevant to analogous material formed in other hydrocarbon-rich environments, such as the surface and atmosphere of Titan and other icy bodies, such as comets, and to the results of in situ analyses of extraterrestrial organic matter.

The carbonaceous chondrite meteorites are fragments of asteroids that have remained relatively unprocessed since the formation of the Solar System 4.56 billion years ago. The major organic component in these meteorites is a macromolecular phase that is resistant to solvent extraction. The information contained within macromolecular material can be accessed by degradative techniques such as pyrolysis. Hydropyrolysis refers to pyrolysis assisted by high hydrogen gas pressures and a dispersed sulphided molybdenum catalyst. Hydropyrolysis of the Murchison macromolecular material successfully releases much greater quantities of hydrocarbons than traditional pyrolysis techniques (twofold greater than hydrous pyrolysis) including significant amounts of high molecular weight polyaromatic hydrocarbons (PAH) such as phenanthrene, carbazole, fluoranthene, pyrene, chrysene, perylene, benzoperylene and coronene units with varying degrees of alkylation. When hydropyrolysis products are collected using a silica trap immersed in liquid nitrogen, the technique enables the solubilisation and retention of compounds with a wide range of volatilities (i.e. benzene to coronene). This report describes the hydropyrolysis method and the information it can provide about meteorite macromolecular material constitution.

In the next decade, numerous space missions will attempt to detect organic matter on planets and other objects in the Solar System. Recognizing carbon-based life or its remains will be a fundamental goal of future missions. In preparation, studies of organic matter in meteorites are enabling scientists how to discriminate between biogenic and abiogenic materials.

In northern Italy the base of the Tesero Oolite Horizon represents the lithological boundary between the Bellerophon and Werfen Formations and marks one of the most dramatic environmental perturbations in Phanerozoic time. The marl, which directly underlies the Tesero Horizon, contains many indicators of environmental change during the end-Permian mass extinction. At Vigo Meano, near Trento, the marl is relatively thermally immature and contains abundant terrestrially-sourced oxygen containing aromatic compounds such as xanthones, dibenzofurans and dibenzo-p-dioxin as well as abundant alkylated naphthalenes.

Aqueous processes were important modifiers of solid matter during the early stages of solar system history. Lithium isotopes are sensitive indicators of such solid-liquid interactions because 7Li passes preferentially into solution and 6Li remains behind in the solid phase. Lithium isotope ratios of inorganic phases in the Murchison meteorite reveal that the value for the whole rock is simply the average of individual components with widely different isotopic compositions. 7Li content increases from chondrules to phyllosilicate-rich matrices to carbonates, as would be expected from the relative duration each component has spent during aqueous alteration on the parent asteroid.

During the end-Permian ecological crisis, terrestrial ecosystems experienced preferential dieback of woody vegetation. Across the world, surviving herbaceous lycopsids played a pioneering role in repopulating deforested terrain. We document that the microspores of these lycopsids were regularly released in unseparated tetrads indicative of failure to complete the normal process of spore development. Although involvement of mutation has long been hinted at or proposed in theory, this finding provides concrete evidence for chronic environmental mutagenesis at the time of global ecological crisis. Prolonged exposure to enhanced UV radiation could account satisfactorily for a worldwide increase in land plant mutation. At the end of the Permian, a period of raised UV stress may have been the consequence of severe disruption of the stratospheric ozone balance by excessive emission of hydrothermal organohalogens in the vast area of Siberian Traps volcanism.

Macromolecular organic materials in chondrites display significant variations in carbon and nitrogen stable isotopes. In recent years, these variations have been interpreted as a record of aqueous and thermal processing on asteroids shortly after the birth of the Solar System. In this paper we review and summarize the key data and main interpretative approaches related to this study area. Armed with these methods we attempt to reinterpret the whole rock chondrite data set in the literature.

The recovery of large numbers of meteorites from Antarctica has dramatically increased the amount of extraterrestrial material available for laboratory studies of solar system origin and evolution. Yet, the great age of Antarctic meteorites raises the concern that significant amounts of terrestrial weathering has corrupted their pre-terrestrial record. Organic matter found in carbonaceous chondrites is one of the components most susceptible to alteration by terrestrial processes. To assess the effects of Antarctic weathering on both non-Antarctic and Antarctic chondritic organic matter, a number of CM chondrites have been analyzed. Mossbauer spectroscopy has been used to ascertain pre-terrestrial and terrestrial oxidation levels, while pyrolysis-gas chromatography-mass spectrometry was used to determine the constitution of any organic matter present. Increased oxidation levels for iron bearing minerals within the non-Antarctic chondrites are likely to be a response to increased amounts of parent body aqueous alteration. Parent body processing also appears to remove ether bonds from organic material and alkyl side chains from its constituent units. The iron in Antarctic chondrites is generally more oxidized than that in their non- Antarctic counterparts, reflecting terrestrial weathering. Antarctic weathering of chondritic organic matter appears to proceed in a similar way to parent body aqueous alteration and simply enhances the organic responses observed in the non-Antarctic data set. Degradation of the record of preterrestrial processes in Antarctic chondrites should be taken into account when interpreting data from these meteorites.

The major organic component of carbonaceous chondrites is a solvent-insoluble, high molecular weight macromolecular material that constitutes at least 70% of the total organic content in these meteorites. Analytical pyrolysis is often used to thermally decompose macromolecular organic matter in an inert atmosphere into lower molecular weight fragments that are more amenable to conventional organic analytical techniques. Hydropyrolysis refers to pyrolysis assisted by high hydrogen gas pressures and a dispersed catalytically-active molybdenum sulfide phase. Hydropyrolysis of meteorites has not been attempted previously although it is ideally suited to such studies due to its relatively high yields. Hydropyrolysis of the Murchison macromolecular material successfully releases significant amounts of high molecular weight PAH including phenanthrene, carbazole, fluoranthene, pyrene, chrysene, perylene, benzoperylene and coronene units with varying degrees of alklyation. Analysis of both the products and residue from hydropyrolysis reveals that the meteoritic organic network contains both labile (pyrolysable) and refractory (nonpyrolysable) fractions. Comparisons of hydropyrolysis yields of Murchison macromolecular materials with those from terrestrial coals indicate that the refractory component probably consists of a network dominated by at least five- or six-ring PAH units cross-linked together.

We have performed the first ever combined-element stable isotopic measurements of extraterrestrial molecules. Methane from two carbonaceous chondrites, Murchison and Cold Bokkeveld, was measured for its hydrogen and carbon isotopic compositions. The combined isotopic composition of meteoritic methane reveals information about the indigenous nature of volatile aliphatic organic matter in meteorites and its probable extraterrestrial source environment. Deuterium enrichments relative to the solar nebula 4.6 Gyr ago reflect a contribution from low-temperature chemical reactions in interstellar space. Similar carbon but different hydrogen isotopic compositions for methane in the two meteorite samples probably represent comparable primary origins but varying levels of secondary processing and exchange with isotopically light hydrogen. Our high precision laboratory-obtained measurements provide valuable reference points for observational spectroscopists undertaking astronomical investigations of the stable isotopic composition of extraterrestrial methane.

The carbonaceous chondrites contain significant amounts of carbon- and nitrogen-bearing components, the most abundant of which is organic matter. Stepped combustion data of whole rock and HF/HCl residues of carbonaceous chondrites reveal that the organic material can be subdivided operationally into three components: (1) free organic matter (FOM), which is readily extractable from whole-rock meteorites and is enriched in 13C and 15N; (2) labile organic matter (LOM), which has a macromolecular structure but is liberated by hydrous pyrolysis; LOM is the parent structure for some FOM and is also enriched in 13C and 15N; and (3) refractory organic matter (ROM), which is also macromolecular but is virtually unaffected by hydrous pyrolysis and is relatively depleted in 13C and 15N. The macromolecular entities (LOM and ROM) are by far the most abundant organic components present, and as such, the relative abundances of the 13C- and 15N-enriched LOM and the 13C- and 15N-depleted ROM will have a major influence on the overall isotopic composition of the whole-rock meteorite. Laboratory experiments designed to simulate the effects of parent body aqueous alteration indicate that this form of processing removes LOM from the macromolecular material, allowing ROM to exert a stronger influence on the overall isotopic compositions. Hence, aqueous alteration of macromolecular materials on the meteorite parent body may have a significant control on the stable isotopic compositions of whole-rock carbonaceous chondrites. The enstatite chondrites are also carbon rich but have been subjected to high levels of thermal metamorphism on their parent body. Stepped combustion data of HF/HCl residues of enstatite chondrites indicate, that if they and carbonaceous chondrites inherited a common organic progenitor, metamorphism under reducing conditions appears to incorporate and preserve some of the 13C enrichments in LOM during graphitisation. However, when metamorphism is at its most extreme, the 15N enrichments in LOM are lost.

The free organic components of the Orgueil carbonaceous chondrite have been the subject of much controversy. Several proposals for their source have been put forward including extraterrestrial abiotic processes, extraterrestrial life and terrestrial contamination. In this study we have analysed the free components to assess their distribution and possible sources. Compounds suggestive of terrestrial contamination by essential plant oil derivatives are evident. Their distribution suggests a source such as cleaning products, disinfectant and air-freshener, where they are present in refined form. This study strongly highlights the need for extreme care when interpreting organic data from meteorites with long curational histories. Future meteorites falls and extraterrestrial sample returns should be stored so as to avoid being compromised by similar terrestrial substances.

The exact location of planetary noble gases in meteorites remains unknown but it is inferred to be closely associated with, if not precisely some portion of, the macromolecular organic material in carbonaceous chondrites [1] . Herein we show that for enstatite chondrites the major carbonaceous component is not the carrier of the gases. This may also be true for other chondritic groups. Rather, these gases are all contained in a minor combustible constituent. This situation has all the hallmarks of a Russian matryoshka doll problem, as was witnessed previously in the study of meteorites prior to the understanding of the presence of presolar grains. A possible conclusion, which is in line with previous suggestions [2] , [3] , is that planetary noble gases are also presolar and located in a new, and as yet unidentified, form of presolar material.

We have performed an investigation to detect high molecular weight organic matter in martian meteorites. Solvent-extracted samples of two Antarctic 5nds (ALH 84001, sub-sample 106 and EET A79001, sub-sample 351) and one non-Antarctic fall (Nakhla) were analysed by :ash pyrolysis–gas chromatography–mass spectrometry. Results suggest that our sub-sample of ALH 84001 contains no pyrolysable organic matter. In contrast, our samples of EET A79001 and Nakhla contain organic matter of high molecular weight, which releases aromatic and alkylaromatic hydrocarbons, phenol and benzonitrile as major compounds upon pyrolysis. The detection of similar pyrolysis products from Nakhla and EET A79001 indicates that these martian meteorites may have a common high molecular weight organic phase. Carbon isotopic measurements of individual molecules in the Nakhla pyrolysate, by :ash pyrolysis– gas chromatography–isotope ratio mass spectrometry, reveal that this high molecular weight organic matter has some similarities to that found in carbonaceous chondrites. At this point, an origin by terrestrial contamination cannot be unequivocally ruled out, but the data seem to support proposals that martian samples contain organic matter originating from meteoritic infall on Mars. The results suggest that a wider, pyrolysis-based study of martian meteorites would be a justi5able use of these precious samples. ? 2002 Elsevier Science Ltd. All rights reserved.

Covering: 1950s to the present day The carbonaceous chondrite meteorites are fragments of asteroids that have remained relatively unprocessed since the formation of the solar system 4.6 billion years ago. These carbon-rich objects contain a variety of extraterrestrial organic molecules that constitute a record of chemical evolution prior to the origin of life. Compound classes include aliphatic hydrocarbons, aromatic hydrocarbons, amino acids, carboxylic acids, sulfonic acids, phosphonic acids, alcohols, aldehydes, ketones, sugars, amines, amides, nitrogen heterocycles, sulfur heterocycles and a relatively abundant high molecular weight macromolecular material. Structural and stable isotopic characteristics suggest that a number of environments may have contributed to the organic inventory, including interstellar space, the solar nebula and the asteroidal meteorite parent body. This review covers work published between 1950 and the present day and cites 193 references.

Data from the Viking and Mars Science Laboratory missions indicate the presence of organic compounds that are not definitively martian in origin. Both contamination and confounding mineralogies have been suggested as alternatives to indigenous organic carbon. Intuitive thought suggests that we are repeatedly obtaining data that confirms the same level of uncertainty. Bayesian statistics may suggest otherwise. If an organic detection method has a true positive to false positive ratio greater than one, then repeated organic matter detection progressively increases the probability of indigeneity. Bayesian statistics also reveal that methods with higher ratios of true positives to false positives give higher overall probabilities and that detection of organic matter in a sample with a higher prior probability of indigenous organic carbon produces greater confidence. Bayesian statistics, therefore, provide guidance for the planning and operation of organic carbon detection activities on Mars. Suggestions for future organic carbon detection missions and instruments are as follows: (i) On Earth, instruments should be tested with analog samples of known organic content to determine their true positive to false positive ratios. (ii) On the mission, for an instrument with a true positive to false positive ratio above one, it should be recognized that each positive detection of organic carbon will result in a progressive increase in the probability of indigenous organic carbon being present; repeated measurements, therefore, can overcome some of the deficiencies of a less-than-definitive test. (iii) For a fixed number of analyses, the highest true positive to false positive ratio method or instrument will provide the greatest probability that indigenous organic carbon is present. (iv) On Mars, analyses should concentrate on samples with highest prior probability of indigenous organic carbon; intuitive desires to contrast samples of high prior probability and low prior probability of indigenous organic carbon should be resisted.

The production of gaseous sulfur-containing species during the steam-assisted recovery of heavy oil and bitumen have important consequences for both economics and safety. Factors such as the effects of mineral matrices require laboratory data to produce accurate models. To study mineral effects on gas production we studied a well-characterized oil-containing core and the isolated crude oil from that core. The samples were run at 250–300°C in the continued presence of liquid water for 24 hours. The reaction products of all experiments include gases, oil flotate, oil sinkate, water-soluble products, and water-insoluble residues. All reaction products were studied with a variety of analytical techniques, including FTIR spectroscopy, chromatographic fractionation (SARA analysis), GC-MS, pyrolysis GCMS and GC-FPD/TCD. These techniques were applied to whole oil, maltenes and asphaltene fractions. Physical properties including viscosity and density were also measured. Our data provide insights into the physical and chemical consequences of steam assisted recovery of heavy oils and bituments from sedimentary rock reservoirs and reveal that geological and geochemical context is an essential consideration.

The nesting habits of ants play an important role in structuring ant populations. They vary from monodomy, a colony occupies a single nest, via polydomy, a colony occupies multiple adjacent nests, to supercoloniality, a colony spans over large territories comprising dozen to thousands nests without having any boundaries. The population structure of the desert ant Cataglyphis niger, previously considered to form supercolonies, was studied using genetic, chemical, and behavioral tools in plots of 50 × 50 m at two distinct populations. At the Palmahim site, the plot comprised 15 nests that according to the genetic analysis constituted three colonies. Likewise at the Rishon Leziyyon site 14 nests constituted 5 genetic colonies. In both sites, both chemical analysis and the behavioral (aggression) tests confirmed the colony genetic architecture. The behavioral tests also revealed that aggression between colonies within a population was higher than that exhibited between colonies of different populations, suggesting the occurrence of the “nasty neighbor” phenomenon. In contrast to supercolony structure previously reported in another population of this species, the presently studied populations were composed of polydomous colonies. However, both the genetic and chemical data revealed that the inter-colonial differences between sites were larger than those within site, suggesting some within-site population viscosity. Thus, C. niger exhibits flexible nesting characteristics, from polydomy to supercoloniality, and can be considered at the brink of supercoloniality. We attribute the differences in population structure among sites to the intensity of intraspecific competition.

Primitive meteorites contain significant amounts of carbon, the majority of which is present as organic matter. Low molecular weight compound classes include aliphatic and aromatic hydrocarbons, amino acids, nucleic acid bases, carboxylic acids, phosphonic acids, sulfonic acids, sugar-related compounds, and organohalogens. Yet, the low molecular weight compounds are minor components relative to a high molecular weight, predominantly aromatic network. Some of the organic matter exists in morphologically distinct microvesicles or nanoglobules and appears to associate with clay minerals in the matrix. As bona fide prebiotic organic compounds, the meteoritic organic matter provides valuable insights into the chemical evolution in the early solar system and the reactions that preceded the origin of life on Earth.

A number of extraterrestrial objects, such as meteorites and interplanetary dust particles, are known to contain organic matter in the form of complex macromolecular materials. These organic networks constitute a useful record of the extraterrestrial environment in which they were formed. This record is most successfully accessed by using a combination of isotopic and structural data. However, obtaining this type of information with current analytical strategies involves relatively large amounts of precious extraterrestrial samples. We have assessed the ability of on-line pyrolysis–gas chromatography–isotope ratio mass spectrometry (Py–GC–IRMS) to obtain isotopic and structural information from the macromolecular material in the Murchison meteorite. Py–GC–IRMS provides results that are consistent with previously published data from other analytical strategies, but with considerably reduced sample sizes. Py–GC–IRMS can now be used to obtain combined isotopic and structural information from macromolecular materials in milligram-sized extraterrestrial samples.

In the time period since 1961, n-alkanes (straight-chain hydrocarbons) have been detected in varying amounts in many meteorites. Proposed origins for these compounds have included extraterrestrial biotic, extraterrestrial abiotic and terrestrial contamination processes. To help establish the source of these compounds, we determined the carbon isotopic compositions of individual n-alkanes in meteorites of several different classes and terrestrial histories: Orgueil (CI1), Cold Bokkeveld (CM2), Murchison (CM2), Vigarano (CV3), Allende (CV3), Ornans (CO3), and Bishunpur (LL3). The efficiency of supercritical fluid extraction (SFE) was exploited to provide extractable non-polar organic matter from the meteorites. The n-alkanes in these extracts were then identified with gas chromatography–mass spectrometry (GC–MS) and the carbon isotopic composition of individual molecules was determined using isotope ratio monitoring–gas chromatography–mass spectrometry (irm–GC–MS). n-Alkanes were found in all but one of the meteorites analysed (Allende), but carbon number distributions varied between samples. Pristane and Phytane were also detected in five of the seven meteorites. δ13C values for the individual n-alkanes occupied a range from −25.3 to −38.7‰. The δ13C values for the meteoritic n-alkanes have a similar range as those for n-alkanes measured from petroleum in the literature. Therefore, the n-alkanes in meteorites appear to be terrestrial contaminants which may have originated from fossil hydrocarbons or petroleum products. This type of contamination is analogous to that which will be threatening future meteorite falls and the samples returned from spaceflight missions over the next two decades and beyond. For falls already contaminated, irm–GC–MS appears useful in discriminating between indigenous compounds and those introduced by terrestrial contamination.

The carbonaceous chondrite meteorites contain a variety of extraterrestrial organic molecules. These organic components provide a valuable insight into the formation and evolution of the solar system. Attempts at obtaining and interpreting this information source are hampered by the small sample sizes available for study and the interferences from terrestrial contamination. Supercritical fluid extraction represents an efficient and contamination-free means of isolating extraterrestrial molecules. Gas chromatography-mass spectrometry analyses of extracts from Orgueil and Cold Bokkeveld reveal a complex mixture of free non-polar organic molecules which include normal alkanes, isoprenoid alkanes, tetrahydronaphthalenes and aromatic hydrocarbons. These organic assemblages imply contributions from both terrestrial and extraterrestrial sources.

The carbonaceous chondrite meteorites contain a record of the formation of the solar system, part of which is present within organic matter. This organic matter is predominantly aromatic, and its sources remain controversial. The d13C values for individual free and macromolecular aromatic moieties from Cold Bokkeveld and Murchison suggest that these units originate from radiation-induced ii circle ˇˇ reac- tions involving simultaneous bond synthesis and cracking. Large carbon isotope fractionations and a deuterium enrichment for these entities suggest that these reactions occurred in a dense interstellar cloud. The juxtaposition of the synthesis and cracking products implies that the reactions occurred in a restricting medium, the most likely candidate for which is the icy organic mantles of interstellar grains. In contrast, the d13C record in aromatic moieties from Orgueil is mostly obscured, possibly due to the increased levels of parent body aqueous alteration experienced by this meteorite. These novel obser- vations are consistent with the interstellarparent body hypothesis, where the —nal form of meteoritic organic matter results from the trans—guration of interstellar organic precursors by aqueous reactions on the meteorite parent body. Subject headings: ISM: moleculesmeteors, meteoroidsmethods: laboratory The carbonaceous chondrites are a unique class of mete- orite that may originate from the C-type asteroids in the outer asteroid belt. These asteroids are ancient and, together with the meteorites derived from them, constitute a record of the birth of the solar system following the collapse of its dense interstellar cloud precursor. Carbonaceous chondrites can contain up to 5% of carbon by weight, the majority of which is present as organic matter. Using the Murchison meteorite as an example, over 90% of the organic matter in carbonaceous chondrites is present as high molecular weight macro- molecular material, with the remainder made up of low molecular weight free compounds (Mullie & Reisse 1987). Aromatic hydrocarbons account for over 5% of the free organic matter (Mullie & Reisse 1987) and are genetically related to the dominantly aromatic macromolecular material (Sephton, Pillinger, & Gilmour 1998). It follows, therefore, that aromatic moieties are quantitatively the most important organic constituents in carbonaceous chon- drites. The dominance of aromatic moieties in carbonaceous chondrites indicates that they are key to understanding the origin of meteoritic organic matter as a whole. The sources of aromatic organic matter in meteorites remain controver- sial, and circumstellar space (Allamandola, Sandford, & Wopenka 1987), the solar nebula (Basile, Middleditch, & 1984; Morgan et al. 1991), and the asteroidal meteorite Oroc

Hydrous pyrolysis, supercritical fluid extraction (SFE), gas chromatography-mass-spectrometry (GC-MS) and isotope ratio monitoring-gas chromatography-mass spectrometry (irm-GC-MS) were used to investigate the constitution of macromolecular materials in meteorites. Results from the carbonaceous chondrites Orgueil (CI1) and Cold Bokkeveld (CM2) were compared with those obtained previously from Murchison (CM2). Fragments of meteoritic macromolecular materials were produced by hydrous pyrolysis, extracted by SFE, and identified by GC-MS. The CI1 and CM2 hydrous pyrolysates all contain volatile aromatic compounds, some of which have aliphatic side chains, hydroxyl groups, and thiophene rings attached. The results indicate that the macromolecular materials in these meteorites are qualitatively similar. However, the pyrolysates show significant quantitative differences, with the products of ether linkages and condensed aromatic networks being less abundant in the more aqueously altered meteorites. In addition, the methylnaphthalene maturity parameter negatively correlates with aqueous alteration. These features are interpreted as the result of chemical reactions favored under hydrous conditions. Hence, the extent of aqueous alteration on the meteorite parent body appears to be the most important evolutionary stage in determining the final structure of macromolecular materials in the CI1 and CM2 meteorites. The carbon isotopic compositions of the fragments of macromolecular materials were determined by irm-GC-MS. δ13C values for the hydrous pyrolysis products range from −25.5 to −10.2‰ for Orgueil and −22.9 to +4.0‰ for Cold Bokkeveld. These values can be compared to the −24.6 to −5.6‰ range obtained previously for Murchison. The low molecular weight components in each hydrous pyrolysate display shifts to increased 13C contents with carbon number. This indicates the production of simple organic entities by the preferential cracking of 12C-12C bonds in more complex starting materials. The shifts extend from C7 to C8 for Orgueil and Cold Bokkeveld but from C7 to C10 for Murchison. Higher molecular weight components for all of the hydrous pyrolysates show a general trend of decreasing 13C content with carbon number. The higher molecular weight features can be explained by the preferential addition of 12C during the primary synthesis of the macromolecular materials. In addition, δ13C values for the methylnaphthalenes are consistent with the addition of 12C to the most reactive site on the naphthalene parent molecule providing supporting evidence for synthesis. Hence, the macromolecular materials are composed of organic units created by both synthesis and cracking. Therefore, secondary processing by liquid water on the meteorite parent body exerts a strong control on the final molecular architecture of meteoritic macromolecular materials. Yet, the carbon isotopic compositions of some individual moieties may retain a record of primary synthesis.

Abundant cyclic diaryl ethers, such as dibenzofuran and its alkyl derivatives are found in solvent extracts and kerogen pyrolysates of a Late Permian organic-rich marl from northern Italy. These organic compounds are distinguishable from biphenyl and its alkyl derivatives by high resolution GC–MS. Bulk geochemical (Rock-Eval) and transmitted/reflected light microscopic analyses indicate that the dominant source of organic matter in the sediment is from partially decomposed land plant debris which has been transported into the marine depositional setting. A likely origin for the cyclic diaryl ether moieties is dehydrated and condensed polysaccharides. Possible sources for the polysaccharides are the organic constituents of land plants, microbes and fungi.

Analyses of the organic compounds in the Murchison meteorite have led to a greater understanding of the nature of extraterrestrial organic materials. However, the relationship between low and high molecular weight material remains poorly understood. To investigate this relationship, untreated Murchison was subjected to supercritical fluid extraction (SFE) to obtain the free organic components in the meteorite. Toluene and other volatile aromatic hydrocarbons dominated the extract, and the carbon isotopic composition of these molecules was determined by gas chromatography-isotope ratio-mass spectrometry (GCIRMS). δ 13 C values of the aromatic hydrocarbons ranged from −28.8 to −5.8‰. These compounds displayed a 13 C-enrichment with increasing carbon number suggesting an origin by cracking. The high molecular weight organic material in the meteorite was isolated and subjected to hydrous pyrolysis. This procedure produced a number of aromatic products, the majority of which were volatile aromatic hydrocarbons, particularly toluene. SFE was used to extract and successfully retain them. This enabled the first carbon isotopic analysis of this poorly understood material to be performed at the molecular level by GCIRMS. δ 13 C values for aromatic pyrolysis products occupied a range from −24.6 to −5.6‰. The trend of 13 C-enrichment with increasing carbon number, observed in the free compounds, was also evident in the macromolecular fragments. Furthermore, the organic fragments of the macromolecular material were consistently 13 C-enriched when compared to structurally identical free molecules. This suggested that the free aromatic hydrocarbons in Murchison were produced by the preterrestrial degradation of the organic macromolecular material. This natural degradation event was extended by the hydrous pyrolysis experiment.

Compound-specific stable carbon isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry is an effective and risk-free means of investigating fatty acid metabolism. Straightforward analysis, however, leads to poor chromatographic resolution, while derivatization adds carbon thereby corrupting the starting stable isotopic composition. Hydropyrolysis is a new approach which defunctionalizes fatty acids to yield the corresponding n-alkanes thus retaining the carbon skeleton intact and improving chromatography, allowing the faithful measurement of carbon isotope ratios.

The production of gaseous sulfur-containing species during the steam-assisted recovery of heavy oil and bitumen presents problems owing to their toxicity, corrosion properties and odor. In order to quantitatively study aquathermolysis sulfur chemistry during the thermal (steam-assisted) recovery of heavy oils we have subjected a well-characterized and sulfur-rich bitumen core sample to 150 - 325°C and 70 - 1740 psia (0.48 - 12 MPa) conditions in the continued presence of liquid water for 24 hours. The reaction products include gases, oil flotate, oil sinkate, water-soluble products, and water- insoluble residues. All have been studied with a variety of analytical techniques, including FTIR spectroscopy, chromatographic fractionation (SARA analysis), GC-FPD and GC-MS. Moreover, these techniques have been extended to analysis of the asphaltene fractions. Results suggest that some in-situ upgrading of the oil occurs under these conditions; additionally, gaseous hydrogen sulfide is released at temperatures at and above 250 °C. Variations in the relative abundances of solubility classes and chemical fractions imply that the source of sulfur is via the thermal degradation of resins and/or asphaltenes. The experimental methods, results and quantification approach discussed herein will be useful to support the development of models for engineering design of facilities for the steam-assisted recovery of heavy oils and bitumen.

Understanding the processes involved in the evolution of organic matter in the early Solar System requires extensive experimental work. The scientifically valuable carbonaceous chondrites are principal targets for organic analyses, but these meteorites are rare. Meteoritic analog materials available in larger quantities, on which experiments can be performed, would be highly beneficial. The bulk of the organic inventory of carbonaceous chondrites is made up of solvent-insoluble macromolecular material. This high-molecular-weight entity provides a record of thermal and aqueous parent-body alteration of precursor organic structures present at the birth of the Solar System. To identify an effective analogue for this macromolecular material, we analyzed a series of terrestrial kerogens by pyrolysis-gas chromatography-mass spectrometry. Type I and II kerogens are unsuitable analogues owing to their highly aliphatic nature. Type III kerogens show some similarities to meteoritic macromolecular materials but display a substantial biological heritage. Type IV kerogens, in this study derived from Mesozoic paleosols and produced by the reworking and oxidation of organic matter, represent an effective analogue. Some isomeric differences exist between meteoritic macromolecular materials and type IV kerogens, and stepped pyrolysis indicates variations in thermal stability. In addition to being a suitable material for novel experimentation, type IV kerogens also have the potential to aid in the optimization of instruments for deployment on Mars.

International audience; Abstract-Hydrothermal processing on planetesimals in the early solar system produced new mineral phases, including those generated by the transformation of anhydrous silicates into their hydrated counterparts. Carbonaceous chondrites represent tangible remnants of such alteration products. Lithium isotopes are known to be responsive to aqueous alteration, yet previously recognized variability within whole rock samples from the same meteorite appears to complicate the use of these isotopes as indicators of processing by water. We demonstrate a new way to use lithium isotopes that reflects aqueous alteration in carbonaceous chondrites. Temperature appears to exert a control on the production of acetic acid-soluble phases, such as carbonates and poorly crystalline Fe-oxyhydroxides. Temperature and degree of water-rock interaction determines the amount of lithium isotope fractionation expressed as the difference between whole rock and acetic acid-leachable fractions. Using these features, the type 1 chondrite Orgueil (d7Li(whole rock) = 4.3&; D7Li(acetic-whole) = 1.2&) can be distinguished from the type 2 chondrites Murchison (d7Li(whole rock) = 3.8; D7Li(acetic-whole) = 8.8&) and carbonate-poor Tagish Lake (d7Li(whole rock) = 4.3; D7Li(acetic-whole) = 9.4&). This initial study suggests that lithium isotopes have the potential to reveal the role of liquid water in the early solar system.

The Life Marker Chip intends to use an aqueous surfactant solution to extract both polar AND nonpolar biomarkers from the martian soil for transport to an antibody-based detection system. Currently, a solution of 1.5 g l-1 polysorbate 80 in 20:80 (vol:vol) methanol:water is being considered and appears to be suitable. However, should this solution be shown to be unsuitable for the LMC or the martian environment, it will be necessary to use a different surfactant. Here, we have investigated the ability of a range of other surfactant solutions to extract a suite of eight standards spiked on the surfaces of the martian soil simulant JSC Mars-1 and tested the compatibility of the best two surfactants with a representative antibody assay for the detection of pyrene. The results show that using 20:80 (vol:vol) methanol:water as the solvent leads to greater recoveries of standards than using water alone. The poloxamer surfactants Pluronic® F-68 and F-108 are not effective at extracting the standards from JSC Mars-1 at any of the concentrations tested here. The fluorosurfactant Zonyl® FS- 300 is able to extract the standards, but not as efficiently as polysorbate 80 solutions. Most successful of the alternative surfactants was the siloxane-based surfactant poly[dimethylsiloxane-co-[3-(2-(2- hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) which is able to extract the standards from JSC Mars-1 about as efficiently as polysorbate 80 solutions. Enhanced recovery of the standards using polysorbate 80 solutions can be achieved by increasing the concentration of polysorbate 80, from 1.5 g l-1 to 10 g l-1, leading to an increase in the recovery of standards of about 50%; a similar increase in effectiveness is also apparent for PDMSHEPMS. Polysorbate 80 at concentrations of 1.5 g l-1 and 10 g l-1 and Zonyl® FS-300 and PDMSHEPMS (both at a concentration of 10 g l-1) are also compatible with the representative pyrene antibody ass

Several robotic exploration missions will travel to Mars during this decade to investigate habitability and the possible presence of life. Field research at Mars analogue sites such as desert environments can provide important constraints for instrument calibration, landing site strategies and expected life detection targets. We have characterized the mineralogy, organic chemistry and microbiology of ten selected sample sites from the Utah desert in close vicinity to the Mars Desert Research Station (MDRS) during the EuroGeoMars 2009 campaign (organized by International Lunar Exploration Working Group (ILEWG), NASA Ames and ESA ESTEC). Compared with extremely arid deserts (such as the Atacama), organic and biological materials can be identified in a larger number of samples and subsequently be used to perform correlation studies. Among the important findings of this field research campaign are the diversity in the mineralogical composition of soil samples even when collected in close proximity, the low abundances of detectable polycyclic aromatic hydrocarbons (PAHs) and amino acids and the presence of biota of all three domains of life with significant heterogeneity. An extraordinary variety of putative extremophiles, mainly Bacteria and also Archaea and Eukarya was observed. The dominant factor in measurable bacterial abundance seems to be soil porosity and lower small (clay-sized) particle content. However, correlations between many measured parameters are difficult to establish. Field research conducted during the EuroGeoMars 2009 campaign shows that the geological history and depositional environment of the region, as well as the mineralogy influence the ability to detect compounds such as amino acids and DNA. Clays are known to strongly absorb and bind organic molecules often preventing extraction by even sophisticated laboratory methods. Our results indicate the need for further development and optimization of extraction procedures that release biological compounds from host matrices to enable the effective detection of biomarkers during future sampling campaigns on Earth and Mars.

Future space missions that aim to detect life should search for molecules that are vital to all living organisms. Although the Viking landers did not find any signs of organic molecules on Mars, signatures of past and/or present life may still exist in the Martian regolith. In this paper, we describe amino acid analyses performed in several Martian analogue soil samples collected close to the Mars Desert Research Station (MDRS), Utah, during the International Lunar Exploration Working Group (ILEWG) EuroGeoMars campaign in February 2009. The Utah desert around Hanksville is characterized as shale desert and is cold and arid with an average annual temperature of 12°C. It is subjected to wind erosion and was shaped by fluvial erosion. The data show large differences in the total amino acid abundances between all the collected soil samples, with values ranging from non-detectable to 100 000 parts per billion (ppb). These results are explained in the context of mineralogical differences (namely different clay content) among the soil samples. The data have implications for future life-detection missions and the target mineralogy that may host biological signatures.

Current attempts to develop a proxy for Earth’s surface ultraviolet-B (UV-B) flux focus on the organic chemistry of pollen and spores because their constituent biopolymer, sporopollenin, contains UV-B absorbing pigments whose relative abundance may respond to the ambient UV-B flux. Fourier transform infrared (FTIR) microspectroscopy provides a useful tool for rapidly determining the pigment content of spores. In this paper, we use FTIR to detect a chemical response of spore wall UV-B absorbing pigments that corresponds with levels of shade beneath the canopy of a high-latitude Swedish birch forest. A 27% reduction in UV-B flux beneath the canopy leads to a significant ( p

Compound-specific stable carbon isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is an important method for the determination of the 13C/12C ratios of biomolecules such as steroids, for a wide range of applications. However, steroids in their natural form exhibit poor chromatographic resolution, while derivatisation adds carbon thereby corrupting the stable isotopic composition. Hydropyrolysis with a sulphided molybdenum catalyst has been shown to defunctionalise the steroids, while leaving their carbon skeleton intact, allowing for the accurate measurement of carbon isotope ratios. The presence of double bonds in unsaturated steroids such as cholesterol resulted in significant rearrangement of the products, but replacing the original catalyst system with one of platinum results in higher conversions and far greater selectivity. The improved chromatographic performance of the products should allow GC/C/IRMS to be applied to more structurally complex steroid hormones and their metabolites. Copyright © 2010 John Wiley & Sons, Ltd.

Surface features observed on Mars and evidence from martian meteorites both suggest that hydrothermal systems have operated in the crust of the planet. Hydrothermal systems are a potential habitat for living organisms and identifying these on Mars is, therefore, important in the search for life beyond the Earth. One of the surface expressions of hydrothermal systems on Earth are silica sinters, deposited during the cooling of hydrothermal solutions. In this paper we present analyses of the mineralogy, textures, chemistry and organic chemistry of silica sinters from two very different geothermal provinces, Waiotapu, New Zealand and Haukadalur, Iceland, in order to determine common features by which silica sinters can be identified. Infrared reflectance spectroscopy was utilised in combination with textural studies to evaluate the mineralogy of sinter deposits in terms of the abundances of different polymorphs of SiO2. Concentrations of organic molecules, principally lipids, within regions of the sinters in which there is textural evidence for micro-organisms were identified in the infrared spectral data and their presence was confirmed using gas chromatography mass spectroscopy. The results of this study indicate that reflectance spectra in the wavelength region from 2.5 to 14 μm, when calibrated against natural terrestrial analogues, can be used to identify silica sinters, as well as the possible presence of recent microbial communities on Mars.

Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)-FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are known to vary depending on the rate of heating, with lower heating rates of biomass associated with increased yields of solid char and decreased yields of volatiles, as well as a greater opportunity for secondary reactions between the residue and the pyrolysis products. Hence, it is difficult to relate the products of organic matter thermally degraded at

Lipid biomarker analyses of sedimentary organic matter from a marine Triassic-Jurassic (T-J) section at Queen Charlotte Islands, British Columbia reveal significant bacterial activity and microbial community changes that coincide with faunal extinctions across the T-J boundary. Bacterial activity is indicated by the 25-norhopane biodegradation index (25-norhopanes / 25-norhopanes+regular hopanes). Microbial community changes is revealed by variations in relative abundance of 2-methylhopane which is mainly generated from cyanobacteria. The 2-methylhopane index (2-methyl hopane/ C30 hopane + C29 25-norhopane) increases above the radiolarian based T-J boundary, and coincides with changes in the 25-norhopane index. The data reveal a complex microbial event involving both autotrophic and heteorotrophic bacteria responding to variations in allochthonous organic matter and nutrient supply.