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At least 217 records · Page 12

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NASA NTRS2005

Study Uncovers Dirty Little Secret: Soil Emissions are Much-Bigger-than-Expected Component of Air Pollution

Nitrogen oxides produced by huge fires and fossil fuel combustion are a major component of air pollution. They are the primary ingredients in ground-level ozone, a pollutant harmful to human health and vegetation. But new research led by a University of Washington atmospheric scientist shows that, in some regions, nitrogen oxides emitted by the soil are much greater than expected and could play a substantially larger role in seasonal air pollution than previously believed. Nitrogen oxide emissions total more than 40 million metric tons worldwide each year, with 64 percent coming from fossil fuel combustion, 14 percent from burning and a surprising 22 percent from soil, said Lyatt Jaegle, a UW assistant professor of atmospheric sciences. The new research shows that the component from soil is about 70 percent greater than scientists expected. Instead of relying on scattered ground-based measurements of burning and combustion and then extrapolating a global total for nitrogen oxide emissions, the new work used actual observations recorded in 2000 by the Global Ozone Monitoring Experiment aboard the European Space Agency's European Remote Sensing 2 satellite. Nitrogen oxide emissions from fossil fuel combustion are most closely linked to major population centers and show up in the satellite's ozone-monitoring measurements of nitrogen dioxide, part of the nitrogen oxides family.

Stricherz, Vince↗

NASA NTRS2004

Microbial Paleontology, Mineralogy and Geochemistry of Modern and Ancient Thermal Spring Deposits and Their Recognition on the Early Earth and Mars"

The vision of this project was to improve our understanding of the processes by which microbiological information is captured and preserved in rapidly mineralizing sedimentary environments. Specifically, the research focused on the ways in which microbial mats and biofilms influence the sedimentology, geochemistry and paleontology of modem hydrothermal spring deposits in Yellowstone national Park and their ancient analogs. Toward that goal, we sought to understand how the preservation of fossil biosignatures is affected by 1) taphonomy- the natural degradation processes that affect an organism from the time of its death, until its discovery as a fossil and 2) diagenesis- longer-term, post-depositional processes, including cementation and matrix recrystallization, which collectively affect the mineral matrix that contains fossil biosignature information. Early objectives of this project included the development of observational frameworks (facies models) and methods (highly-integrated, interdisciplinary approaches) that could be used to explore for hydrothermal deposits in ancient terranes on Earth, and eventually on Mars.

Farmer, Jack D.↗

NASA NTRS2008

Intercomparison of SCIAMACHY and OMI Tropospheric NO2 Columns: Observing the Diurnal Evolution of Chemistry and Emissions from Space

Concurrent (August 2006) measurements of tropospheric NO2 columns from OMI aboard Aura (1330 local overpass time) and SCIAMACHY aboard Envisat (1000 local overpass time) offer an opportunity to examine the consistency between the two instruments under tropospheric background conditions and the effect of different observing times. For scenes with tropospheric NO 2 columns <5.0 x 10(exp 15) molecules cm 2, SCIAMACHY and OMI agree within 1.0-2.0 x 10(exp 15) molecules cm 2, consistent with the detection limits of both instruments. We find evidence for a low bias of 0.2 x 10(exp 15) molecules cm 2 in OMI observations over remote oceans. Over the fossil fuel source regions at northern midlatitudes, we find that SCIAMACHY observes up to 40% higher NO2 at 1000 local time (LT) than OMI at 1330 LT. Over biomass burning regions in the tropics, SCIAMACHY observes up to 40% lower NO 2 columns than OMI. These differences are present in the spectral fitting of the data (slant column) and are augmented in the fossil fuel regions and dampened in the tropical biomass burning regions by the expected increase in air mass factor as the mixing depth rises from 1000 to 1330 LT. Using a global 3-D chemical transport model (GEOS-Chem), we show that the 1000-1330 LT decrease in tropospheric NO2 column over fossil fuel source regions can be explained by photochemical loss, dampened by the diurnal cycle of anthropogenic emissions that has a broad daytime maximum. The observed 1000-1330 LT NO2 column increase over tropical biomass burning regions points to a sharp midday peak in emissions and is consistent with a diurnal cycle of emissions derived from geostationary satellite fire counts.

Boersma, K. Folkert↗

NASA NTRS2011

Reducing US Oil Dependence Using Simulation

People across the world are addicted to oil; as a result, the instability of oil prices and the shortage of oil reserves have influenced human behaviors and global businesses. Today, the United States makes up only 5% of the global population but consumes 25% of the. world total energy. Most of this energy is generated from fossil fuels in the form of electricity. The contribution of this paper is to examine the possibilities of replacing fossil fuel with renewable energies to generate electricity as well as to examine other methods to reduce oil and gas consumption. We propose a system dynamics model in an attempt to predict the future US dependence on fossil fuels by using renewable energy resources such as, nuclear, wind, solar, and hydro powers. Based on the findings of our model, the study expects to provide insights towards promising solutions of the oil dependency problem.

Ayoub, Fadi↗

NASA NTRS2011

Global Night-Time Lights for Observing Human Activity

We present a concept for a small satellite mission to make systematic, global observations of night-time lights with spatial resolution suitable for discerning the extent, type and density of human settlements. The observations will also allow better understanding of fine scale fossil fuel CO2 emission distribution. The NASA Earth Science Decadal Survey recommends more focus on direct observations of human influence on the Earth system. The most dramatic and compelling observations of human presence on the Earth are the night light observations taken by the Defence Meteorological System Program (DMSP) Operational Linescan System (OLS). Beyond delineating the footprint of human presence, night light data, when assembled and evaluated with complementary data sets, can determine the fine scale spatial distribution of global fossil fuel CO2 emissions. Understanding fossil fuel carbon emissions is critical to understanding the entire carbon cycle, and especially the carbon exchange between terrestrial and oceanic systems.

Hipskind, Stephen R.↗

NASA NTRS2017

Young People's Burden: Requirement of Negative CO2 Emissions

Global temperature is a fundamental climate metric highly correlated with sea level, which implies that keeping shorelines near their present location requires keeping global temperature within or close to its preindustrial Holocene range. However, global temperature excluding short-term variability now exceeds +1 C relative to the 1880 - 1920 mean and annual 2016 global temperature was almost +1.3 C. We show that global temperature has risen well out of the Holocene range and Earth is now as warm as it was during the prior (Eemian) interglacial period, when sea level reached 6 - 9 m higher than today. Further, Earth is out of energy balance with present atmospheric composition, implying that more warming is in the pipeline, and we show that the growth rate of greenhouse gas climate forcing has accelerated markedly in the past decade. The rapidity of ice sheet and sea level response to global temperature is difficult to predict, but is dependent on the magnitude of warming. Targets for limiting global warming thus, at minimum, should aim to avoid leaving global temperature at Eemian or higher levels for centuries. Such targets now require "negative emissions", i.e., extraction of CO2 from the air. If phasedown of fossil fuel emissions begins soon, improved agricultural and forestry practices, including reforestation and steps to improve soil fertility and increase its carbon content, may provide much of the necessary CO2 extraction. In that case, the magnitude and duration of global temperature excursion above the natural range of the current interglacial (Holocene) could be limited and irreversible climate impacts could be minimized. In contrast, continued high fossil fuel emissions today place a burden on young people to undertake massive technological CO2 extraction if they are to limit climate change and its consequences. Proposed methods of extraction such as bioenergy with carbon capture and storage (BECCS) or air capture of CO2 have minimal estimated costs of USD 89 - 535 trillion this century and also have large risks and uncertain feasibility. Continued high fossil fuel emissions unarguably sentences young people to either a massive, implausible cleanup or growing deleterious climate impacts or both.

Hansen, James↗

NASA NTRS2018

A Diverse Mammal-Dominated, Footprint Assemblage from Wetland Deposits in the Lower Cretaceous of Maryland

A newly discovered assemblage of predominantly small tracks from the Cretaceous Patuxent Formation at NASA’s Goddard Space Flight Center, Maryland, reveals one of the highest track densities and diversities ever reported (~70 tracks, representing at least eight morphotypes from an area of only ~2 m(exp 2)). The assemblage is dominated by small mammal tracks including the new ichnotxon Sederipes goddardensis, indicating sitting postures. Small crow-sized theropod trackways, the first from this unit, indicate social trackmakers and suggest slow-paced foraging behavior. Tracks of pterosaurs, and other small vertebrates suggest activity on an organic-rich substrate. Large well-preserved sauropod and nodosaurs tracks indicate the presence of large dinosaurs. The Patuxent Formation together with the recently reported Angolan assemblage comprise the world’s two largest Mesozoic mammal footprint assemblages. The high density of footprint registration at the NASA site indicates special preservational and taphonomic conditions. These include early, penecontemporaneous deposition of siderite in organic rich, reducing wetland settings where even the flesh of body fossils can be mummified. Thus, the track-rich ironstone substrates of the Patuxent Formation, appear to preserve a unique vertebrate ichnofacies, with associated, exceptionally-preserved body fossil remains for which there are currently no other similar examples preserved in the fossil record.

Ray Stanford↗

NASA NTRS2021

Improved Constraints on Global Methane Emissions and Sinks Using δ13C-CH4

We study the drivers behind the global atmospheric methane (CH4) increase observed after 2006. Candidate emission and sink scenarios are constructed based on proposed hypotheses in the literature. These scenarios are simulated in the TM5 tracer transport model for 1984–2016 to produce three-dimensional fields of CH4 and δ13C-CH4, which are compared with observations to test the competing hypotheses in the literature in one common model framework. We find that the fossil fuel (FF) CH4 emission trend from the Emissions Database for Global Atmospheric Research 4.3.2 inventory does not agree with observed δ13C-CH4. Increased FF CH4 emissions are unlikely to be the dominant driver for the post-2006 global CH4 increase despite the possibility for a small FF emission increase. We also find that a significant decrease in the abundance of hydroxyl radicals (OH) cannot explain the post-2006 global CH4 increase since it does not track the observed decrease in global mean δ13C-CH4. Different CH4 sinks have different fractionation factors for δ13C-CH4, thus we can investigate the uncertainty introduced by the reaction of CH4 with tropospheric chlorine (Cl), a CH4 sink whose abundance, spatial distribution, and temporal changes remain uncertain. Our results show that including or excluding tropospheric Cl as a 13 Tg/year CH4 sink in our model changes the magnitude of estimated fossil emissions by ∼20%. We also found that by using different wetland emissions based on a static versus a dynamic wetland area map, the partitioning between FF and microbial sources differs by 20 Tg/year, ∼12% of estimated fossil emissions.

X. Lan↗

NASA NTRS2015

Ah, Sweet Mystery of Life, OSIRIS-REx May Find You

The nature of the origin of life is a topic that has engaged people since ancient times. Where did we come from? What was the first life? How are we related? Are we alone? The study of biologic remains and environments preserved in rocks (fossils) and biochemical pathways and structures found across organisms (molecular fossils) can address these questions. Molecular evidence shows that all life on Earth is related fundamentally, biology shares a genetic language, related molecular machinery, and common chemistry By looking at the details of genetic and protein sequences more detailed relationships can be determined for modern organisms.

origin of life↗

NASA NTRS1995

Microfossils from the Neoarchean Campbell Group, Griqualand West Sequence of the Transvaal Supergroup, and their paleoenvironmental and evolutionary implications

The oldest filament- and colonial coccoid-containing microbial fossil assemblage now known is described here from drill core samples of stromatolitic cherty limestones of the Neoarchean, approximately 2600-Ma-old Campbell Group (Ghaap Plateau Dolomite, Lime Acres Member) obtained at Lime Acres, northern Cape Province, South Africa. The assemblage is biologically diverse, including entophysalidacean (Eoentophysalis sp.), probable chroococcacean (unnamed colonial coccoids), and oscillatoriacean cyanobacteria (Eomycetopsis cf. filiformis, and Siphonophycus transvaalensis), as well as filamentous fossil bacteria (Archaeotrichion sp.); filamentous possible microfossils (unnamed hematitic filaments) also occur. The Campbell Group microorganisms contributed to the formation of stratiform and domical to columnar stromatolitic reefs in shallow subtidal to intertidal environments of the Transvaal intracratonic sea. Although only moderately to poorly preserved, they provide new evidence regarding the paleoenvironmental setting of the Campbell Group sediments, extend the known time-range of entophysalidacean cyanobacteria by more than 400 million years, substantiate the antiquity and role in stromatolite formation of Archean oscillatoriacean cyanobacteria, and document the exceedingly slow (hypobradytelic) evolutionary rate characteristic of this early evolving prokaryotic lineage.

Non-NASA Center↗

NASA NTRS1996

Lithofacies and biofacies of mid-Paleozoic thermal spring deposits in the Drummond Basin, Queensland, Australia

The Devonian to Carboniferous sinters of the Drummond Basin, Australia, are among the oldest well established examples of fossil subaerial hot springs. Numerous subaerial and subaqueous spring deposits are known from the geological record as a result of the occurrence of economic mineral deposits in many of them. Some are reported to contain fossils, but very few have been studied by paleobiologists; they represent an untapped source of paleobiological information on the history of hydrothermal ecosystems. Such systems are of special interest, given the molecular biological evidence that thermophilic bacteria lie near the root of the tree of extant life. The Drummond Basin sinters are very closely comparable with modern examples in Yellowstone National Park and elsewhere. Thirteen microfacies are recognisable in the field, ranging from high temperature apparently abiotic geyserite through various forms of stromatolitic sinter probably of cyanobacterial origin to ambient temperature marsh deposits. Microfossils in the stromatolites are interpreted as cyanobacterial sheaths. Herbaceous lycopsids occur in the lower temperature deposits.

NASA Center ARC↗

NASA NTRS1996

Integrated chronostratigraphy of Proterozoic-Cambrian boundary beds in the western Anabar region, northern Siberia

Carbonate-rich sedimentary rocks of the western Anabar region, northern Siberia, preserve an exceptional record of evolutionary and biogeochemical events near the Proterozoic/Cambrian boundary. Sedimentologically, the boundary succession can be divided into three sequences representing successive episodes of late transgressive to early highstand deposition; four parasequences are recognized in the sequence corresponding lithostratigraphically to the Manykal Formation. Small shelly fossils are abundant and include many taxa that also occur in standard sections of southeastern Siberia. Despite this coincidence of faunal elements, biostratigraphic correlations between the two regions have been controversial because numerous species that first appear at or immediately above the basal Tommotian boundary in southeastern sections have first appearances scattered through more than thirty metres of section in the western Anabar. Carbon- and Sr-isotopic data on petrographically and geochemically screened samples collected at one- to two-metre intervals in a section along the Kotuikan River, favour correlation of the Staraya Reckha Formation and most of the overlying Manykai Formation with sub-Tommotian carbonates in southeastern Siberia. In contrast, isotopic data suggest that the uppermost Manykai Formation and the basal 26 m of the unconformably overlying Medvezhya Formation may have no equivalent in the southeast; they appear to provide a sedimentary and palaeontological record of an evolutionarily significant time interval represented in southeastern Siberia only by the sub-Tommotian unconformity. Correlations with radiometrically dated horizons in the Olenek and Kharaulakh regions of northern Siberia suggest that this interval lasted approximately three to six million years, during which essentially all 'basal Tommotian' small shelly fossils evolved.

Non-NASA Center↗

NASA NTRS1992

Microfossils and possible microfossils from the Early Archean Onverwacht Group, Barberton Mountain Land, South Africa

There is widespread textural evidence for microbial activity in the cherts of the Early Archean Onverwacht Group. Layers with fine carbonaceous laminations resembling fossil microbial mats are abundant in the cherty metasediments of the predominantly basaltic Hooggenoeg and Kromberg Formations. In rare cases, filamentous microfossils are associated with the laminae. The morphologies of the fossils, as well as the texture of the encompassing laminae suggest an affinity to modern mat-dwelling cyanobacteria or bacteria. A variety of spheroidal and ellipsoidal structures present in cherts of the Hooggenoeg and Kromberg Formations resemble modern coccoidal bacteria and bacterial structures, including spores. The development of spores may have enabled early microorganisms to survive the relatively harsh surficial conditions, including the effects of very large meteorite impacts on the young Earth.

Non-NASA Center↗

NASA NTRS1989

The historic biogeography of India: isolation or contact?

Geophysical maps depicting continental movement have consistently shown India, as it moved northward, to be located far out in the Tethys Sea. India split off from the African east coast about 148 m.y.a. From that time onward, according to almost all geophysical accounts, India was isolated from all of other continents until the early Miocene when it made contact with Eurasia. But the biological data, both fossil and Recent, indicate that this concept cannot be correct. If India had really existed as an isolated, oceanic continent for about 100 m.y., it should have developed a peculiar biota with many endemic genera and families in its terrestrial and shallow marine habitats. But there are virtually no remains of organisms indicating that India was isolated for any substantial time (millions of years). Instead, we find that almost all Indian taxa were possessed in common with other continents. As time went on, the northern relationships became stronger and the southern ones weaker. Most of the recent geophysical accounts show India not making contact with Eurasia until the early Miocene, but fossil materials show that this event must have taken place by the early Eocene. It has been postulated that, as India moved northward, it created a biogeographic barrier that separated marine fish populations and resulted in the east-west provinces that are now apparent in the Indian Ocean. At the same time, the barrier effect was supposed to have resulted in the formation of sister species that are now located far apart. Information currently available indicates that most living, tropical marine species are probably not over 3 m.y. old. Consequently, the northward movement of India, which took place primarily between 148 and 50 m.y.a., could have no bearing on the relationships of modern species.

NASA Discipline Exobiology↗

NASA NTRS1988

Distribution and diagenesis of microfossils from the lower Proterozoic Duck Creek Dolomite, Western Australia

Two distinct generations of microfossils occur in silicified carbonates from a previously undescribed locality of the Lower Proterozoic Duck Creek Dolomite, Western Australia. The earlier generation occurs in discrete organic-rich clasts and clots characterized by microquartz anhedra; it contains a variety of filamentous and coccoidal fossils in varying states of preservation. Second generation microfossils consist almost exclusively of well-preserved Gunflintia minuta filaments that drape clasts or appear to float in clear chalcedony. These filaments appear to represent an ecologically distinct assemblage that colonized a substrate containing the partially degraded remains of the first generation community. The two assemblages differ significantly in taxonomic frequency distribution from previously described Duck Creek florules. Taken together, Duck Creek microfossils exhibit a range of assemblage variability comparable to that found in other Lower Proterozoic iron formations and ferruginous carbonates. With increasing severity of post-mortem alteration, Duck Creek microfossils appear to converge morphologically on assemblages of simple microstructures described from early Archean cherts. Two new species are described: Oscillatoriopsis majuscula and O. cuboides; the former is among the largest septate filamentous fossils described from any Proterozoic formation.

NASA Discipline Number 52-30↗

NASA NTRS1993

Did Mars once have martians?

Pictures of Mars from the Viking and Mariner 9 missions provide evidence of liquid water in Mars' past, indicating a warmer climate. It is speculated that outflow channels and valley networks were formed 3.5 to 4 billions years ago, at the same time life was developing on Earth. Current theories suggest that chemical reactions in Mars' early atmosphere depleted the original amounts of carbon dioxide with no mechanism to recycle it back into the atmosphere. Ecosystems in the cold, dry Antarctic valleys provide models of Mars on Earth and indicate that if life evolved on Mars there may be organic or fossil evidence under the surface. Lake beds on Mars surface are considered to be the best place to hunt for fossils.

NASA Center ARC↗

NASA NTRS1987

Early Archean (3.3-billion to 3.5-billion-year-old) microfossils from Warrawoona Group, Australia

Cellularly preserved filamentous and colonial fossil microorganisms have been discovered in bedded carbonaceous cherts from the Early Archean Apex Basalt and Towers Formation of northwestern Western Australia. The cell types detected suggest that cyanobacteria, and therefore oxygen-producing photosynthesis, may have been extant as early as 3.3 billion to 3.5 billion years ago. These fossils are among the oldest now known from the geologic record; their discovery substantiates previous reports of Early Archean microfossils in Warrawoona Group strata.

Non-NASA Center↗

NASA NTRS1994

The early evolution of life: solution to Darwin's dilemma

Recent studies of Precambrian fossils indicate that life on Earth originated earlier than assumed, microscopic life was prevalent in the Precambrian Eon, the tempo and mode of evolution during the Precambrian period were different from other periods, and that only the Precambrian fossil record can be used as evidence of early life. Implications for future research include directing the search for the origin of life away from the geological record, modification of hypotheses about molecular change, use of Precambrian microfossils in dating younger geological units, and progress in defining the nature of major events in early evolution.

Non-NASA Center↗