Preprints
Filtering by Subject: Biogeochemistry
The organic component of the earliest sulfur cycling
Published: 2019-01-16
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
The chemistry of the Early Earth is widely inferred from the elemental and isotopic compositions of sulfidic sedimentary rocks, which are presumed to have formed globally through the reduction of seawater sulfate or locally from hydrothermally supplied sulfide. Here we argue that, in the sulfate-poor ferruginous oceans of the Archean eon, organic sulfur must have played an important and [...]
Critical Review of Polyphosphate and Polyphosphate Accumulating Organisms for Agricultural Water Quality Management
Published: 2018-12-04
Subjects: Agriculture, Biogeochemistry, Earth Sciences, Environmental Microbiology and Microbial Ecology Life Sciences, Environmental Sciences, Life Sciences, Microbiology, Natural Resources Management and Policy, Physical Sciences and Mathematics, Soil Science, Water Resource Management
Despite ongoing management efforts, phosphorus (P) loading from agricultural landscapes continues to impair water quality. Wastewater treatment research has enhanced our knowledge of microbial mechanisms influencing P cycling, especially regarding microbes known as polyphosphate accumulating organisms (PAOs) that store P as polyphosphate (polyP) under oxic conditions and release P under anoxic [...]
Geomorphology and Climate Interact to Control Organic Carbon Stock and Age in Mountain River Valley Bottoms
Published: 2018-10-09
Subjects: Biogeochemistry, Earth Sciences, Geomorphology, Physical Sciences and Mathematics
Organic carbon (OC) in valley bottom downed wood and soil that cycles over short to moderate timescales represents a large, dynamic, and poorly quantified pool of carbon whose distribution and residence time affects global climate. We compare four disparate mountain river basins to show that mountain river valley bottoms store substantial estimated OC stocks in floodplain soil and downed wood. [...]
Grand Challenges (and Great Opportunities) in Sedimentology, Stratigraphy, and Diagenesis Research
Published: 2018-09-23
Subjects: Biogeochemistry, Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Technological advances make these exciting times for geoscientists studying Earth surface processes, their depositional products, and interactions with the biosphere, hydrosphere, atmosphere, and lithosphere; from monitoring contemporary sediment transport processes to interpretation of sedimentary archives that record ancient environmental changes. We set out three research challenges: 1) [...]
Quantifying the Fate of Wastewater Nitrogen Discharged to a Canadian River
Published: 2018-06-21
Subjects: Biogeochemistry, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics, Systems Biology, Water Resource Management
Addition of nutrients, such as nitrogen, can degrade water quality in lakes, rivers, and estuaries. To predict the fate of nutrient inputs, an understanding of the biogeochemical cycling of nutrients is needed. We develop and employ a novel, parsimonious, process-based model of nitrogen concentrations and stable isotopes that quantifies the competing processes of volatilization, uptake, [...]
Pervasive iron limitation at subsurface chlorophyll maxima of the California Current
Published: 2018-05-25
Subjects: Biogeochemistry, Earth Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Subsurface chlorophyll maximum layers (SCMLs) are nearly ubiquitous in stratified water columns and exist at horizontal scales ranging from the submesoscale to the extent of oligotrophic gyres. These layers of heightened chlorophyll and/or phytoplankton concentrations are generally thought to be a consequence of a balance between light energy from above and a limiting nutrient flux from below, [...]
Towards a global interpretation of dual nitrate isotopes in natural water
Published: 2018-05-23
Subjects: Biogeochemistry, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Sciences, Physical Sciences and Mathematics, Water Resource Management
Modern anthropogenic activities have significantly increased nitrate (NO3-) concentrations in surface waters. Stable isotopes (δ15N and δ18O) in NO3- offer a tool to deconvolute some of the human-made changes in the nitrogen cycle. They are often graphically illustrated on a template designed to identify different sources of NO3- and denitrification. In the two decades since this template was [...]
Metabolite cycling indicated by long-range correlation in a sediment bioreactor mixed microbial community
Published: 2018-05-17
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
Geophysical surveys add value to biogeochemical studies because of their ability to characterize systems remotely, and their precise time resolution. One limitation, however, is their lack of biogeochemical process specificity. Here, electrochemical time series from an oxic-anoxic cyclical bioreactor experiment were reanalyzed with detrended fluctuation analysis (DFA) to distinguish dominant [...]
EarthN: A new Earth System Nitrogen Model
Published: 2018-05-04
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth’s biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, [...]
What caused Earths largest mass extinction event? New evidence from the Permian-Triassic boundary in northeastern Utah
Published: 2018-02-27
Subjects: Biogeochemistry, Biology, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Indicators and Impact Assessment, Environmental Sciences, Geology, Life Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology
The discovery of a Permian-Triassic boundary section in northeastern Utah reveals a detailed record of events that led to one of the greatest mass extinctions on the planet. From 83% to 97% of the species living on the planet went extinct during this relatively short interval of geological time, which defines the major geological boundary between the Paleozoic and Mesozoic Eras. The cause and [...]
Distributions of geohopanoids in peat: implications for the use of hopanoid-based proxies in natural archives
Published: 2018-02-05
Subjects: Biogeochemistry, Chemistry, Earth Sciences, Environmental Sciences, Geochemistry, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Hopanoids are pentacyclic triterpenoids produced by a wide range of bacteria. Within modern settings, hopanoids mostly occur in the biological 17β,21β(H) configuration. However, in some modern peatlands, the C31 hopane is present as the thermally-mature 17α,21β(H) stereoisomer. This has traditionally been ascribed to isomerisation at the C-17 position catalysed by the acidic environment. However, [...]
Macrostrat: a platform for geological data integration and deep-time Earth crust research
Published: 2018-01-27
Subjects: Biogeochemistry, Earth Sciences, Geology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Characterizing the lithology, age, and physical-chemical properties of rocks and sediments in the Earths upper crust is necessary to fully assess energy, water, and mineral resources and to address many fundamental questions in the Earth sciences. Although a large number of geological maps, regional geological syntheses, and sample-based measurements have been produced, there is no openly [...]
Drought Conditions Maximize the Impact of High-Frequency Flow Variations on Thermal Regimes and Biogeochemical Function in the Hyporheic Zone
Published: 2018-01-16
Subjects: Biogeochemistry, Earth Sciences, Hydrology, Physical Sciences and Mathematics
Anthropogenic activities, especially dam operations, often induce larger and more frequent stage fluctuations than those occurring in natural rivers. However, long-term impacts of such flow variations on thermal and biogeochemical dynamics of the associated hyporheic zone (HZ) are poorly understood. In this study, we built a heterogeneous, two-dimensional, thermo-hydro-biogeochemical model for a [...]
Recycling of archaeal biomass as a new strategy for extreme life in Dead Sea deep sediments
Published: 2017-12-15
Subjects: Biogeochemistry, Chemistry, Earth Sciences, Organic Chemistry, Physical Sciences and Mathematics
Archaea and Bacteria that inhabit the deep subsurface (known as the deep biosphere) play a prevalent role in the recycling of sedimentary organic carbon. In such environments, this process can occur over millions of years and requires microbial communities to cope with extremely limited sources of energy. Because of this scarcity, metabolic processes come at a high energetic cost, but the ways [...]
Quantifying closed-basin lake temperature and hydrology by inversion of oxygen isotope and trace element paleoclimate records
Published: 2017-11-09
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Lake systems are important paleoclimate archives that preserve ecosystem and hydrologic responses to critical periods in Earth history, such as carbon cycle perturbations and glacial-interglacial cycles. Geochemical measurements of biogenic carbonate (for example, δ18O, δ13C, 87Sr/86Sr, [Li], [U], [Sr], and [Mg]) are indicators of hydrologic variability in lake systems throughout the geologic [...]