Preprints

Filtering by Subject: Biogeochemistry

Redox-informed models of global biogeochemical cycles

Emily Zakem, Martin Polz, Mick Follows

Published: 2019-10-07
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics

Microbial activity mediates the global flow of carbon, oxygen, nitrogen, and other elements, including climatically significant gases. However, non-photosynthetic microbial activity is typically not resolved dynamically or mechanistically in global models of the marine and terrestrial biospheres, inhibiting predictive capability. Understanding the global-scale impact of complex microbial [...]

Controls of River Dynamics on Residence Time and Biogeochemical Reactions of Hydrological Exchange Flows in A Regulated River Reach

Xuehang Song, Xingyuan Chen, John M. Zachara, Jesus D. Gomez-Velez, Pin Shuai, Huiying Ren, Glenn Hammond

Published: 2019-10-06
Subjects: Biogeochemistry, Earth Sciences, Hydrology, Physical Sciences and Mathematics

Residence Time Distributions (RTDs) exerts an important control on biogeochemical translations in watershed systems. RTDs tend to follow time-invariant exponential, lognormal, or heavy-tailed RTDs that have power-law behaviors for long tails in headwater or low-order streams. However, there is increasing recognition that RTDs can be more complicated and time-variable in response to dynamic [...]

Mercury loading within the Selenga River Basin and Lake Baikal, Siberia

Sarah Roberts, Jennifer K Adams, Anson W. Mackay, George Swann, Suzanne McGowan, Neil L. Rose, Virginia Panizzo, Handong Yang, Elena Vologina, Michael Sturm

Published: 2019-09-28
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics

Mercury (Hg) loading in Lake Baikal, a UNESCO world heritage site, is growing and poses a serious health concern to the lake’s ecosystem due to the ability of Hg to transform into a toxic form, known as methylmercury (MeHg). Monitoring of Hg into Lake Baikal is spatially and temporally sparse, highlighting the need for insights into historic Hg loading. This study reports measurements of Hg [...]

What Fractionates Oxygen Isotopes During Respiration? Insights from Multiple Isotopologues and Theory

Jeanine Ash, Huanting Hu, Laurence Y Yeung

Published: 2019-08-21
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics

The precise mass dependence of respiratory O2 consumption underpins the “oxygen triple-isotope” approach to quantifying gross primary productivity in modern and ancient environments. Yet, the physical-chemical origins of the key 18O/16O and 17O/16O covariations observed during respiration have not been tied to theory; thus the approach remains empirical. First-principles calculations on enzyme [...]

Vertical Eddy Iron Fluxes Support Primary Production in the Open Southern Ocean

Takaya Uchida, Dhruv Balwada, Ryan Abernathey, Galen McKinley, Shafer Smith, Marina Levy

Published: 2019-08-04
Subjects: Biogeochemistry, Earth Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

The primary productivity of the Southern Ocean ecosystem, and associated biological carbon pump, is limited by the availability of the micronutrient iron. Riverine sediments and atmospheric dust supply iron at the ocean margins, but in the vast open ocean, iron reaches phytoplankton primarily when iron-rich sub-surface waters enter the euphotic zone, linking vertical transport processes to [...]

Relationships between soil chemical properties and rare earth element concentrations in the aboveground biomass of a tropical herbaceous plant

Olivier Pourret, Lange , Martinez RE, Wiche O, Faucon MP

Published: 2019-07-18
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics

The geochemical behavior of rare earth elements (REE) has been mainly investigated in geological systems where they represent the best proxies for processes occurring at the interface between different media. REE concentrations, normalized with respect to the upper continental crust, were used to assess their behavior. In this study, REE geochemical behavior was investigated in plant shoots of a [...]

The Baltic TRANSCOAST approach – investigating shallow coasts as terrestrial-marine interface of water and matter fluxes

Manon Janssen, Michael E Böttcher, Martin Brede, Hans Burchardt, Stefan Forster, Ulf Karsten, Peter Leinweber, Bernd Lennartz, Gregor Rehder, Hendrik Schubert

Published: 2019-07-16
Subjects: Biogeochemistry, Biology, Earth Sciences, Environmental Monitoring, Environmental Sciences, Hydrology, Life Sciences, Marine Biology, Oceanography and Atmospheric Sciences and Meteorology, Other Oceanography and Atmospheric Sciences and Meteorology, Other Plant Sciences, Physical Sciences and Mathematics, Plant Sciences, Soil Science

In Baltic TRANSCOAST we study the physical, biogeochemical, and biological processes at the land-ocean interface. The coastal zone is heavily impacted by various human activities as well as by geomorphological and climatic processes – on both the land and the sea side. Land-sea interactions at low lying coastal areas that are often dominated by peatlands, and are a common feature along the Baltic [...]

δ13C values of bacterial hopanoids and leaf waxes as tracers for methanotrophy in peatlands

Gordon Neil Inglis, B. David. A. Naafs, Yanhong Zheng, Judith Schellekens, Richard D. Pancost

Published: 2019-07-08
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics

Methane emissions from peatlands contribute significantly to atmospheric CH4 levels and play an essential role in the global carbon cycle. The stable carbon isotopic composition (δ13C) of bacterial and plant lipids has been used to study modern and past peatland biogeochemistry, especially methane cycling. However, the small number of recent peatlands that have been characterised and the lack of [...]

Probing the chemical transformation of seawater-soluble crude oil components during microbial oxidation

Yina Liu, Helen White, Rachel Simister, David Waite, Shelby Lyons, Elizabeth Kujawinski

Published: 2019-06-18
Subjects: Biogeochemistry, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Sciences, Life Sciences, Microbiology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Physical Sciences and Mathematics

Studies assessing the environmental impacts of oil spills focus primarily on the non-water-soluble components, leaving the fate of the water-soluble fraction (WSF) largely unexplored. We employed untargeted chemical analysis along with biological information to probe the transformation of crude oil WSF in seawater, in the absence of light, in a laboratory experiment. Over a 14-day incubation, [...]

The glacial express

Kevin Geyer Harrison

Published: 2019-05-31
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics

Glacial calcium carbonate (CaCO3) shells are larger than interglacial CaCO3 shells. My research explores the consequences of this size difference. Because larger CaCO3 shells sink faster and dissolve more slowly than smaller CaCO3 shells, larger glacial shells underwent less dissolution than smaller interglacial shells. The resulting CaCO3 transport efficiency increase, coupled with observations [...]

Marine biomarkers from ice cores reveal enhanced high-latitude Southern Ocean carbon sink during the Antarctic Cold Reversal

Christopher Fogwill, Chris Stewart MacGregor Turney, Laurie Menviel, Andy Baker, Michael Weber, Bethany Ellis, Zoë Thomas, Nick Golledge, David Etheridge, Mauro Rubino

Published: 2019-05-31
Subjects: Biogeochemistry, Earth Sciences, Glaciology, Paleontology, Physical Sciences and Mathematics

Determining the feedbacks that modulate Southern Ocean carbon dynamics is key to understanding past and future climate. The global pause in rising atmospheric CO2 during the period of mid- to high-latitude southern surface cooling known as the Antarctic Cold Reversal (ACR, 14,700-12,700 years ago) provides an opportunity to disentangle competing influences. We present highly-resolved and [...]

Dark carbon fixation contributes to sedimentary organic carbon in the Arabian Sea oxygen minimum zone

Sabine Lengger, Darci Rush, Jan Peter Mayser, Jerome Blewett, Rachel Schwartz-Narbonne, Helen Talbot, Jack Middelburg, Mike Jetten, Stefan Schouten, Jaap Damste

Published: 2019-05-18
Subjects: Biogeochemistry, Earth Sciences, Environmental Microbiology and Microbial Ecology Life Sciences, Life Sciences, Microbiology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

In response to rising CO2 concentrations and increasing global sea surface temperatures, oxygen minimum zones (OMZ), or “dead zones”, are expected to expand. OMZs are fueled by high primary productivity, resulting in enhanced biological oxygen demand at depth, subsequent oxygen depletion, and attenuation of remineralization. This results in the deposition of organic carbon-rich sediments. Carbon [...]

A first look at dissolved Ge isotopes in marine sediments

J. Jotautas Baronas, Douglas E Hammond, Olivier Rouxel, Danielle R Monteverde

Published: 2019-04-28
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics

The removal of chemical species from seawater during the precipitation of authigenic minerals is difficult to constrain but may play a major role in the global biogeochemical cycles of some elements, including silicon (Si) and germanium (Ge). Here, we present Ge/Si, δ74Ge, and supporting chemical data of pore waters and core incubations at three continental margin sites in California and the Gulf [...]

Terrestrial environmental change across the onset of the PETM and the associated impact on biomarker proxies: a cautionary tale

Gordon Neil Inglis, Alexander Farnsworth, Margaret Collinson, Matthew Carmichael, B. David. A. Naafs, Dan Lunt, Paul J Valdes, Richard D. Pancost

Published: 2019-04-28
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics

The Paleocene-Eocene Thermal Maximum (PETM; ~ 56 million years ago (Ma) is the most severe carbon cycle perturbation event of the Cenozoic. Although the PETM is associated with warming in both the surface (~up to 8°C) and deep ocean (~up to 5°C), there are relatively few terrestrial temperature estimates from the onset of this interval. The associated response of the hydrological cycle during the [...]

A long-term, high-latitude record of Eocene hydrological change in the Greenland region

Gordon Neil Inglis, Matthew Carmichael, Alexander Farnsworth, Dan Lunt, Richard D. Pancost

Published: 2019-04-26
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics

A range of proxy approaches have been used to reconstruct short-term changes to Earth’s hydrological cycle during the early Eocene hyperthermals. However, little is known about the response of Earth’s hydrological and biogeochemical systems to long-term Cenozoic cooling, which began following the Early Eocene Climatic Optimum (53.3 – 49.4 million years ago; Ma). Here, we use the molecular [...]

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