Projects

Decomposition of complex organics in icy satellite interiors  (NASA 80-NSSC-19K0559)

Miller K., Foustoukos D., G. Cody and C. Alexander

Complex organic material comprises approximately 4 wt.% of carbonaceous chondrites and up to 25 wt.% of comets. Since small bodies record conditions during planet formation, organic materials may have been a major component of planetary building blocks in the outer solar system. During partial differentiation, icy satellites therefore may have incorporated significant masses of organics in their cores. Open pyrolysis experiments at ambient pressure on insoluble organic matter (IOM) from carbonaceous chondrites show that these materials begin to decompose to more volatile species at temperatures below 200 degrees Celsius. This is consistent with production of oil and gas from terrestrial kerogen, which begins at ~100 degrees Celsius. However, parallel pyrolysis experiments on IOM and kerogen differ significantly in the temperature dependence of volatile products (e.g. Okumura and Mimura, 2011). Although there is extensive literature on pyrolysis of kerogen, there are clear limitations to the use of kerogen as an analog for extraterrestrial materials. We study the thermal degradation of extraterrestrial complex organic material in the context of the evolution of outer solar system interiors. Our study will provide the first experimental data on decomposition of extraterrestrial complex organics at pressures (up to 3 kbar) and temperatures (300 to 350 °C) relevant to the interiors of icy satellites to test the extent of volatilization under these conditions. We will study three different samples: 1. synthetic dextrose-based IOM, which is an analog for primitive IOM before alteration on chondrite parent bodies; 2. demineralized IOM extracted from the CM2 chondrite Murchison, which has been selected because it is a relatively abundant relatively organic-rich, and well characterized meteorite sample; 3. whole rock Murchison samples. 

Collaborative Research: Experimental Controls on Clumped Isotope Signatures of CH4 in Deep-Sea Vents   

(NSF - OCE 2308386)

Foustoukos D.I., G.C. Lazar and J. Farquhar

Deep-sea hydrothermal vent systems affect the cycling of carbon between the Earth’s interior and oceans by introducing organic compounds of thermogenic, abiotic and microbial origin to the overlying water column. Vent fluids from both basalt and ultramafic-hosted hydrothermal systems contain abundant CH4 in addition to other organic species. This project focus on the stable C and H isotopic signatures of dissolved CH4 that provide insights on the temperature and mechanisms of formation. This proposal aims to explore the origin and evolution of CH4 in deep-sea vents by employing the use of double-substituted and doubly-deuterated isotopologues (13CH3D, 12CH2 D2 ). In a series of hydrothermal experiments involving organic matter decomposition. CO2  reduction and non-equilibrated CH4 gases in the presence of mineral catalysts, the distribution of rare methane isotopologue will be assessed by the use of a high-mass-resolution gas-source multiple collector mass spectrometer (Panorama, UMD). Experiments will assess the equilibrium relationships in the 12CH2 D2 -13CH3D-12CH3D-12CH4-13CH4-HD-HDO-H2O system and describe isotope effects associated with the impact of mineral phases and H2O H isotope composition on the abiotic and thermogenic formation mechanisms. This study aims to be a comprehensive study of 12CH2D2  and 13CH3D evolution applied to subseafloor hydrothermal systems and water/rock interactions deeper in the oceanic crust.

Collaborative Research: Microbial hydrogen oxidation at high pressure: Role of hydrogenases and interspecies hydrogen transfer   (NSF-IOS 1951673 )

Foustoukos D. and Vetriani C.

A large fraction of Earth’s biosphere lives in the deep ocean and within the oceanic subsurface. This deep biosphere thrives under conditions of high hydrostatic pressures (>10 MPa, 1000 meter depth) and often high-temperatures and is adapted not only to pressure, but also to sharp temperature and redox gradients. Considering the contribution of these thermopiezophilic microbial communities to the Earth’s microbiome, their role in linking the geological and biological element cycles in the deep-ocean, and their relevance for the evolution of early life on Earth, it is striking how little we know about the function and physiological responses of thermopiezophiles to the physical and chemical conditions they encounter in their habitats. This project aims to gain insight into the adaptation mechanisms of thermopiezophilic, hydrogen-oxidizing bacteria to different pressure and hydrogen concentration regimes.  The model organism is Nautilia sp. strain PV-1, a deep-sea vent thermopiezophilic, anaerobic chemolithoautotroph that couples H2 oxidation to either to NO3- or S0 reduction, and whose genome has been sequenced. In aim 1, this project will investigate the expression of the different hydrogenases of strain PV-1 in response to pressures up to 40 MPa, and to limiting and non-limiting concentration of hydrogen. In aim 2, this project will investigate the homeoviscous adaptation of strain PV-1 by investigating membrane lipid saturation at various pressures. In aim 3, this project will investigate synthrophic growth by interspecies hydrogen transfer between Marinitoga piezophila, a fermentative, hydrogen-producing thermopiezophile and the hydrogen consuming strain PV-1. To simulate in-situ physical (temperature, pressure) and chemical (hydrogen concentration) conditions, novel culturing techniques will be employed to recreate the high-pressure, temperature and nutrient conditions of deep-sea hydrothermal vents. 

Kinetics of H and O isotope exchange during hydrothermal alteration of insoluble organis matter 

(NASA 80-NSSC-20K0344)

Foustoukos D., C. Alexander and G. Cody

We investigate alteration processes affecting the isotopic and elemental composition of water and insoluble organic matter (IOM) in chondrite parent bodies. Specifically, experiments have been conducted to constrain: (1) the kinetics of Murchison IOM modification (H/C, N/C) and IOM-water H isotope exchange under hydrothermal conditions as a function of pH and down to lower temperatures than in previous experiments; (2) the elemental/isotopic response of CR IOM at similar hydrothermal conditions to determine if all C1/2 IOM could have a common CR-like precursor; (3) the kinetics of D/H exchange at the molecular level of the functional groups in analog IOM (syn-IOM); and (4) the variation in O/C and O isotope systematics between hydrothermally altered chondritic/syn-IOM and H2O. The aim of the project is to develop a detailed understanding of how the elemental/isotopic composition and structure of IOM in chondrites was modified by metamorphism and aqueous alteration in the chondrite parent bodies. Experimental results will shed light on the isotopic evolution of chondrites after accretion, and the origins of the H2O and organics accreted, the thermal histories of aqueously altered and mildly metamorphosed chondrites. Our experimental results will have implications for: (i) the formation of organics and ice, and their transport in the disk, (ii) the accretion locations, thermal histories and dynamical evolution of asteroids, and (iii) the delivery of volatiles and organics to the terrestrial planets. Ultimately, these experiments will help us to quantitatively understand the origins and evolution of water and organic matter in chondrites and their parent bodies, constrain the chemical and thermal evolution of chondrites/asteroids during alteration, and describe processes of planetesimal and planet formation.

Physiological Adaptations in Hydrogenotrophic Bacteria at Extreme Pressures 

(NASA 80-NSSC-21K0485)

Foustoukos D. and Vetriani C.

We aim to constrain: i) the physiological adaptation of extremophiles to the pressure and nutrient levels found at deep-sea hydrothermal vents, and ii) phage-host interactions and coevolution. We will employ a novel anaerobic, chemolithoautotrophic and thermophilic Epsilonproteobacterium (Nautilia strain PV-1) that exhibits piezophilic growth. The genome of strain PV-1 carries a complete prophage. Task 1: How do piezophiles adapt to pressure gradients present at deep-sea and subsurface environments? We hypothesize that the membrane lipids saturation in Nautilia strain PV-1 decreases as the hydrostatic pressure increases. We will determine the changes in the membrane lipid composition (fatty acids and polar lipids) of strain PV-1 during growth at different pressures. Task 2: What is the role of environmental DNA uptake as an adaptation mechanism to pressure and nutrient-limitation stresses? We hypothesize that low and/or high pressure and nutrient availability regimes differentially affect the expression of DNA uptake genes in Nautilia strain PV-1 when exposed to exogenous DNA. We propose experiments to assess the level of expression of competence-related genes during the uptake of free DNA in strain PV-1. Task 3: We hypothesize that the life cycle of the prophage hosted in Nautilia strain PV-1 is affected by pressure and nutrient conditions that differ from those for optimum growth. We aim to: (i) investigate the pressure adaptation that triggers the lytic cycle of the bacteriophage; (ii) identify the nutrient regimes that trigger lytic cycle in PV-1; and (iii) investigate the ability of the PV-1 phage to infect its relatives in the order Nautiliales.

Investigating the influence of parent-body aqueous alteration on the stable isotopic compositions of meteoritic soluble organic matter

(NASA 80-NSSC-21K0654)

Simkus D., Foustoukos D.I., Dorwkin J., Aponte J., Alexander C., Cody G.

The organic contents of carbonaceous chondrite (CC) meteorites provide a record of the chemical processes and prebiotic inventory of the early Solar System. Stable isotopic analyses of meteoritic organic matter offer insights into their chemical origins, including the synthetic relationships between meteoritic organic compound classes, and the processing history of parent body asteroids. Varying isotopic ratios (δ13C) for soluble organic matter (SOM) across different CC petrologic types indicate a potential relationship between degree of parent body alteration and isotopic values. Likewise, meteoritic insoluble organic matter (IOM) shifts towards isotopically lighter compositions (i.e., towards more negative δ13C values) with increasing degree of hydrothermal alteration, potentially partially attributable to a loss of isotopically heavy labile organic matter. We propose to use laboratory simulations of aqueous alteration followed by δ13C analyses to trace these trends within a controlled system.

REU Site: Earth and Planetary science Interdisciplinary Internships at Carnegie (EPIIC) (NSF-GEO 2244322)

Foustoukos D.I. and J. Teske

The Earth and Planetary science Interdisciplinary Internships program at Carnegie will introduce the process of research at the intersections of: Astronomy, Astrobiology, Bio-/Isotope Geochemistry, Cosmochemistry, Data Science, Experimental Geochemistry, Geophysics, High-Pressure Mineral Physics, Mineralogy, Organic Geochemistry, and Petrology; to undergraduate students without significant previous research experience. The 10-week program is planned to ensure successful completion of students’ research activities and expects their participation in national meetings and peer-review publications. Students will be full members of their mentors’ research groups, attend weekly seminars and social events, and reside together on the campus of American University to help establish a collegial cohort. EPIIC’s intensity and training will prepare its participants for graduate student life. Maintaining student-mentor(s) communications beyond the summer REU program is encouraged to facilitate participant transition into STEM-related careers. The program will be evaluated by a series of surveys and tools employed under the guidance of an external advisor. The long-term success of the program success will be measured by: i) the number of REU students who follow a STEM-related career, including the number of community college students that transfer to a 4-year university as science majors, ii) the extent of the participation of students underrepresented in STEM education, iii) students’ understanding of the broader impacts of scientific discovery on the establishment of an ethical, inclusive and fact-driven society