Filtering by Subject: Biogeochemistry

Separating isotopic impacts of karst and in-cave processes from climate variability using an integrated speleothem isotope-enabled forward model

Pauline Treble, Mukhlis Mah, Alan David Griffiths, Andy Baker, Michael Deininger, Bryce Kelly, Denis Scholz, Stuart Hankin

Published: 2019-03-12
Subjects: Biogeochemistry, Earth Sciences, Hydrology, Physical Sciences and Mathematics, Speleology

Speleothem δ18O values are commonly used to infer past climate variability. However, both non-linear karst hydrological processes and in-cave disequilibrium isotope fractionation are recognised and hinder the interpretation of δ18O values. In recent years, proxy system models (PSMs) have emerged to quantitatively assess the confounding effects of these processes. This study presents the first [...]

Human-induced fire regime shifts during 19th century industrialization: a robust fire regime reconstruction using northern Polish lake sediments

Elisabeth Dietze, Dariusz Brykała, Laura T. Schreuder, Krzysztof Jażdżewski, Olivier Blarquez, Achim Brauer, Michael Dietze, Milena Obremska, Florian Ott, Anna Pieńczewska

Published: 2019-02-22
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Other Earth Sciences, Physical Sciences and Mathematics

Fire regime shifts are driven by climate and natural vegetation changes, but can be strongly affected by human land management. Yet, it is poorly known how exactly humans have influenced fire regimes prior to active wildfire suppression. Among the last 250 years, the human contribution to the global increase in fire occurrence during the mid-19th century is especially unclear, as data sources are [...]

Long Range Correlation in Redox Potential Fluctuations Signals Energetic Efficiency of Bacterial Fe(II) Oxidation

Allison Enright, Brock Edwards, Grant Ferris

Published: 2019-02-21
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics

Differentiating biotic and abiotic processes in nature remains a persistent challenge, specifically in evaluating microbial contributions to geochemical processes through time. Building on previous work reporting that biologically-influenced systems exhibit stronger long-range correlation than abiotic systems, this study evaluated the relationship between long-range correlation of redox [...]

The organic component of the earliest sulfur cycling

Mojtaba Fakhraee, Sergei Katsev

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 [...]

A Critical Review of Polyphosphate Accumulating Organisms for Agricultural Water Quality Management

Sheila M. Saia, Hunter J. Carrick, Anthony R. Buda, John M. Regan, M. Todd Walter

Published: 2018-12-03
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 plant research has enhanced our knowledge of microbial mechanisms influencing P cycling, especially related to microbes known as polyphosphate accumulating organisms (PAOs) that store P as polyphosphate (polyP) under aerobic conditions and release P under [...]

Geomorphology and Climate Interact to Control Organic Carbon Stock and Age in Mountain River Valley Bottoms

Daniel N. Scott, Ellen Wohl

Published: 2018-10-08
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

David Mark Hodgson, Anne Bernhardt, Michael Clare, Anne-Christine da Silva, Julie Fosdick, Barbara Mauz, Ivar Midtkandal, Amanda Owen, Brian Romans

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

Jason J. Venkiteswaran, Sherry Schiff, Brian Ingalls

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

Shane Hogle, Chris L. Dupont, Brian Hopkinson, Andrew L. King, Kristen N. Buck, Kelly L. Roe, Rhona K. Stuart, Andy Allen, Elizabeth L. Mann, Zackary I. Johnson

Published: 2018-05-24
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

Jason J. Venkiteswaran, Pascal Boeckx, Daren Gooddy

Published: 2018-05-22
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

Allison Enright, Christopher T. Parsons, Mihaela Glamoclija

Published: 2018-05-16
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

Benjamin William Johnson, Colin Goldblatt

Published: 2018-05-03
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

Benjamin Burger

Published: 2018-02-26
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

Gordon Neil Inglis, B. David. A. Naafs, Yanhong Zheng, Erin McClymont, Richard Evershed, Richard D. Pancost

Published: 2018-02-04
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

Shanan E Peters, Jon M. Husson, John Czaplewski

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 [...]


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