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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Drought re-routes soil microbial carbon metabolism towards emission of volatile metabolites in an artificial tropical rainforest

Drought impacts on microbial activity can alter soil carbon fate and lead to the loss of stored carbon to the atmosphere as CO 2 and volatile organic compounds (VOCs). Here we examined drought impacts on carbon allocation by soil microbes in the Biosphere 2 artificial tropical rainforest by tracking 13 C from position-specific 13 C-pyruvate into CO 2 and VOCs in parallel with multi-omics. During drought, efflux of 13 C-enriched acetate, acetone and C 4 H 6 O 2 (diacetyl) increased. These changes represent increased production and buildup of intermediate metabolites driven by decreased carbon cycling efficiency. Simultaneously, 13 C-CO 2 efflux decreased, driven by a decrease in microbial activity. However, the microbial carbon allocation to energy gain relative to biosynthesis was unchanged, signifying maintained energy demand for biosynthesis of VOCs and other drought-stress-induced pathways. Overall, while carbon loss to the atmosphere via CO 2 decreased during drought, carbon loss via efflux of VOCs increased, indicating microbially induced shifts in soil carbon fate.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Drought Reduces Formation, but Enhances Persistence, of Mineral‐Associated Organic Matter in a Grassland Soil

Drought effects are pervasive in terrestrial ecosystems, yet there is limited understanding of how drought impacts the transformation of plant carbon (C) inputs to mineral-associated organic matter (MAOM)—the largest and slowest-cycling pool of soil organic carbon (SOC). In a 12-week 13 C-CO 2 greenhouse labeling experiment, we tracked the formation of MAOM derived from the two dominant sources of plant C input to the mineral soil—living root inputs ( 13 C-rhizodeposits) and decaying root inputs ( 13 C-root detritus)—under normal moisture and droughted conditions in a semiarid grassland soil. At the end of the 12-week period, we also measured the persistence of 13 C-MAOM formed from rhizodeposits versus root detritus via a subsequent persistence assay. Drought reduced the formation of MAOM derived from living roots by decreasing rhizodeposits, reducing microbial growth rates, and altering the composition of organic matter, lipids, and metabolites. Drought initially delayed the formation of MAOM derived from root detritus by slowing the early stages of root litter decomposition (week 4–8), but did not decrease total MAOM formation by the end of the 12-week period. Notably, drought enhanced the persistence of MAOM derived from root detritus, but did not influence the persistence of MAOM derived from rhizodeposits. Our results provide some of the first direct evidence that drought can reduce the formation of MAOM in a grassland soil, but may enhance its persistence, based on the source of plant input from which MAOM is derived.

13C- labeling↗
DOE OSTI2020

Materials Data on Co3C by Materials Project

Co3C is Cementite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Co+1.33+ sites. In the first Co+1.33+ site, Co+1.33+ is bonded in a distorted water-like geometry to three equivalent C4- atoms. There are two shorter (1.98 Å) and one longer (2.38 Å) Co–C bond lengths. In the second Co+1.33+ site, Co+1.33+ is bonded in a bent 150 degrees geometry to two equivalent C4- atoms. There is one shorter (1.92 Å) and one longer (1.93 Å) Co–C bond length. C4- is bonded in a 6-coordinate geometry to eight Co+1.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co2C by Materials Project

Co2C is Hydrophilite structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Co2+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Co–C bond lengths are 1.90 Å. C4- is bonded to six equivalent Co2+ atoms to form a mixture of corner and edge-sharing CCo6 octahedra. The corner-sharing octahedral tilt angles are 52°.

36 MATERIALS SCIENCE↗