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Andrew J Rushby, Martin Johnson, Benjamin J W Mills, Andrew J Watson, Mark W Claire
The potential habitability of an exoplanet is traditionally assessed by determining whether its orbit falls within the circumstellar "habitable zone" of its star, defined as the distance at which water could be liquid on the surface of a planet (Kopparapu et al., 2013 ). Traditionally, these limits are determined by radiative-convective climate models, which are used to predict surface temperatures at user-specified levels of greenhouse gases. This approach ignores the vital question of the (bio)geochemical plausibility of the proposed chemical abundances...
May 2018: Astrobiology
Kerstin Jerosch, Hendrik Pehlke, Patrick Monien, Frauke Scharf, Lukas Weber, Gerhard Kuhn, Matthias H Braun, Doris Abele
The coasts of the West Antarctic Peninsula are strongly influenced by glacier meltwater discharge. The spatial structure and biogeochemical composition of inshore habitats are shaped by large quantities of terrigenous particulate material deposited in the vicinity of the coast, which impacts the pelagic and benthic ecosystems. We used a multitude of geochemical and environmental variables to identify the radius extension of the meltwater impact from the Fourcade Glacier into the fjord system of Potter Cove, King George Island...
June 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
John N Christensen, Baptiste Dafflon, Alyssa E Shiel, Tetsu K Tokunaga, Jiamin Wan, Boris Faybishenko, Wenming Dong, Kenneth H Williams, Chad Hobson, Shaun T Brown, Susan S Hubbard
Recharge of alluvial aquifers is a key component in understanding the interaction between floodplain vadose zone biogeochemistry and groundwater quality. The Rifle Site (a former U-mill tailings site) adjacent to the Colorado River is a well-established field laboratory that has been used for over a decade for the study of biogeochemical processes in the vadose zone and aquifer. This site is considered an exemplar of both a riparian floodplain in a semiarid region and a post-remediation U-tailings site. In this paper we present Sr isotopic data for groundwater and vadose zone porewater samples collected in May and July 2013 to build a mixing model for the fractional contribution of vadose zone porewater (i...
May 11, 2018: Science of the Total Environment
Sebastian Haas, Dirk de Beer, Judith M Klatt, Artur Fink, Rebecca McCauley Rench, Trinity L Hamilton, Volker Meyer, Brian Kakuk, Jennifer L Macalady
We report extremely low-light-adapted anoxygenic photosynthesis in a thick microbial mat in Magical Blue Hole, Abaco Island, The Bahamas. Sulfur cycling was reduced by iron oxides and organic carbon limitation. The mat grows below the halocline/oxycline at 30 m depth on the walls of the flooded sinkhole. In situ irradiance at the mat surface on a sunny December day was between 0.021 and 0.084 μmol photons m-2 s-1 , and UV light (<400 nm) was the most abundant part of the spectrum followed by green wavelengths (475-530 nm)...
2018: Frontiers in Microbiology
Sreejata Bandopadhyay, Lluis Martin-Closas, Ana M Pelacho, Jennifer M DeBruyn
Agricultural plastic mulch films are widely used in specialty crop production systems because of their agronomic benefits. Biodegradable plastic mulches (BDMs) offer an environmentally sustainable alternative to conventional polyethylene (PE) mulch. Unlike PE films, which need to be removed after use, BDMs are tilled into soil where they are expected to biodegrade. However, there remains considerable uncertainty about long-term impacts of BDM incorporation on soil ecosystems. BDMs potentially influence soil microbial communities in two ways: first, as a surface barrier prior to soil incorporation, indirectly affecting soil microclimate and atmosphere (similar to PE films) and second, after soil incorporation, as a direct input of physical fragments, which add carbon, microorganisms, additives, and adherent chemicals...
2018: Frontiers in Microbiology
Federico Maggi, Fiona H M Tang, Céline Pallud, Chuanhui Gu
A soil-based cropping unit fuelled with human urine for long-term manned space missions was investigated with the aim to analyze whether a closed-loop nutrient cycle from human liquid wastes was achievable. Its ecohydrology and biogeochemistry were analysed in microgravity with the use of an advanced computational tool. Urine from the crew was used to supply primary (N, P, and K) and secondary (S, Ca and Mg) nutrients to wheat and soybean plants in the controlled cropping unit. Breakdown of urine compounds into primary and secondary nutrients as well as byproduct gases, adsorbed, and uptake fractions were tracked over a period of 20 years...
May 2018: Life Sciences in Space Research
Jiri Kopacek, Christopher D Evans, Josef Hejzlar, Jiří Kaňa, Petr Porcal, Hana Šantrůčková
Forest disturbances affect ecosystem biogeochemistry, water quality and carbon cycling. We analysed water chemistry before, during and after a dieback event at a headwater catchment in the Bohemian Forest (central Europe), together with an unimpacted reference catchment, focusing on drivers and responses of dissolved organic carbon (DOC) leaching. We analysed data on carbon input to the forest floor via litter and throughfall, changes in soil moisture and composition, stream water chemistry, discharge and temperature...
May 8, 2018: Environmental Science & Technology
Laura Barral-Fraga, Diego Martiñá-Prieto, María Teresa Barral, Soizic Morin, Helena Guasch
Gold mining activities in fluvial systems may cause arsenic (As) pollution, as is the case at the Anllóns River (Galicia, NW Spain), where high concentrations of arsenate (AsV ) in surface sediments (up to 270 mg kg-1 ) were found. A 51 day-long biofilm-translocation experiment was performed in this river, moving some biofilm-colonized substrata from upstream (less As-polluted) to downstream the mine area (more As-polluted site), to explore the effect of As on benthic biofilms, as well as their role on As retention and speciation in the water-sediment interface...
May 2, 2018: Science of the Total Environment
Ryan P McClure, Kathleen D Hamre, B R Niederlehner, Zackary W Munger, Shengyang Chen, Mary E Lofton, Madeline E Schreiber, Cayelan C Carey
Metalimnetic oxygen minimum zones (MOMs) commonly develop during the summer stratified period in freshwater reservoirs because of both natural processes and water quality management. While several previous studies have examined the causes of MOMs, much less is known about their effects, especially on reservoir biogeochemistry. MOMs create distinct redox gradients in the water column which may alter the magnitude and vertical distribution of dissolved methane (CH4 ) and carbon dioxide (CO2 ). The vertical distribution and diffusive efflux of CH4 and CO2 was monitored for two consecutive open-water seasons in a eutrophic reservoir that develops MOMs as a result of the operation of water quality engineering systems...
April 30, 2018: Science of the Total Environment
Emmanuel Boss, Nils Haëntjens, Toby K Westberry, Lee Karp-Boss, Wayne H Slade
High spatial and temporal resolution estimates of the particle size distribution (PSD) in the surface ocean can enable improved understanding of biogeochemistry and ecosystem dynamics. Oceanic PSD measurements remain rare due to the time-consuming, manual sampling methods of common particle sizing instruments. Here, we evaluate the utility of measuring particle size data at high spatial resolution with a commercially-available submersible laser diffraction particle sizer (LISST-100X, Sequoia Scientific), operating in an automated mode with continuously flowing seawater...
April 30, 2018: Optics Express
Gabriela Onandia, Gunnar Lischeid, Thomas Kalettka, Andreas Kleeberg, Mohamed Omari, Katrin Premke, George B Arhonditsis
Kettle holes, small shallow ponds of glacial origin, represent hotspots for biodiversity and biogeochemical cycling. They abound in the young moraine landscape of Northeast Germany, potentially modulating element fluxes in a region where intensive agriculture prevails. The Rittgarten kettle hole, with semi-permanent hydroperiod and a surrounding reed belt, can be considered as a representative case study for such systems. Aiming to provide insights into the biogeochemical processes driving nutrient and primary producer dynamics in the Rittgarten kettle hole, we developed a mechanistic model that simulates the carbon, nitrogen, phosphorus and oxygen, phytoplankton, and free-floating macrophyte biomass dynamics...
April 24, 2018: Science of the Total Environment
Andreas Kreuzeder, Jakob Santner, Vanessa Scharsching, Eva Oburger, Christoph Hoefer, Stephan Hann, Walter W Wenzel
Aims: We imaged the sub-mm distribution of labile P and pH in the rhizosphere of three plant species to localize zones and hot spots of P depletion and accumulation along individual root axes and to relate our findings to nutrient acquisition / root exudation strategies in P-limited conditions at different soil pH, and to mobilization pattern of other elements (Al, Fe, Ca, Mg, Mn) in the rhizosphere. Methods: Sub-mm distributions of labile elemental patterns were sampled using diffusive gradients in thin films and analysed using laser ablation inductively coupled plasma mass spectrometry...
2018: Plant and Soil
Indika Herath, Meththika Vithanage, Saman Seneweera, Jochen Bundschuh
Thiolated arsenic compounds are the sulfur analogous substructures of oxo-arsenicals as the arsinoyl (As = O) is substituted by an arsinothioyl (As = S) group. Relatively brief history of thioarsenic research, mostly in the current decade has endeavored to understand their consequences in the natural environment. However, thioarsenic related aspects have by far not attached much research concern on global scale compared to other arsenic species. This review attempts to provide a critical overview for the first time on formation mechanisms of thioarsenicals, their chemistry, speciation and analytical methodologies in order to provide a rational assessment of what is new, what is current, what needs to be known or what should be done in future research...
April 26, 2018: Environment International
Thomas Valdemarsen, Cintia O Quintana, Sandra W Thorsen, Erik Kristensen
How will coastal soils in areas newly flooded with seawater function as habitat for benthic marine organisms? This research question is highly relevant as global sea level rise and coastal realignment will cause flooding of soils and form new marine habitats. In this study, we tested experimentally the capacity of common marine polychaetes, Marenzelleria viridis, Nereis (Hediste) diversicolor and Scoloplos armiger to colonize and modify the biogeochemistry of the newly established Gyldensteen Coastal Lagoon, Denmark...
2018: PloS One
Kyle F Edwards, Grieg F Steward
Viruses are integral to ecological and evolutionary processes, but we have a poor understanding of what drives variation in key traits across diverse viruses. For lytic viruses, burst size, latent period, and genome size are primary characteristics controlling host-virus dynamics. Here we synthesize data on these traits for 75 strains of phytoplankton viruses, which play an important role in global biogeochemistry. We find that primary traits of the host (genome size, growth rate) explain 40%-50% of variation in burst size and latent period...
May 2018: American Naturalist
Hitoshi Matsui, Natalie M Mahowald, Nobuhiro Moteki, Douglas S Hamilton, Sho Ohata, Atsushi Yoshida, Makoto Koike, Rachel A Scanza, Mark G Flanner
Atmospheric iron affects the global carbon cycle by modulating ocean biogeochemistry through the deposition of soluble iron to the ocean. Iron emitted by anthropogenic (fossil fuel) combustion is a source of soluble iron that is currently considered less important than other soluble iron sources, such as mineral dust and biomass burning. Here we show that the atmospheric burden of anthropogenic combustion iron is 8 times greater than previous estimates by incorporating recent measurements of anthropogenic magnetite into a global aerosol model...
April 23, 2018: Nature Communications
Gilad Antler, André Pellerin
Separating the contributions of anaerobic oxidation of methane and organoclastic sulfate reduction in the overall sedimentary sulfur cycle of marine sediments has benefited from advances in isotope biogeochemistry. Particularly, the coupling of sulfur and oxygen isotopes measured in the residual sulfate pool (δ18 OSO4 vs. δ34 SSO4 ). Yet, some important questions remain. Recent works have observed patterns that are inconsistent with previous interpretations. We differentiate the contributions of oxygen and sulfur isotopes to separating the anaerobic oxidation of methane and organoclastic sulfate reduction into three phases; first evidence from conventional high methane vs...
2018: Frontiers in Microbiology
Benjamin D Duval, Rajan Ghimire, Melannie D Hartman, Mark A Marsalis
External inputs to agricultural systems can overcome latent soil and climate constraints on production, while contributing to greenhouse gas emissions from fertilizer and water management inefficiencies. Proper crop selection for a given region can lessen the need for irrigation and timing of N fertilizer application with crop N demand can potentially reduce N2O emissions and increase N use efficiency while reducing residual soil N and N leaching. However, increased variability in precipitation is an expectation of climate change and makes predicting biomass and gas flux responses to management more challenging...
2018: PloS One
Kai Xu, David Hutchins, Kunshan Gao
Background: The globally abundant coccolithophore, Emiliania huxleyi , plays an important ecological role in oceanic carbon biogeochemistry by forming a cellular covering of plate-like CaCO3 crystals (coccoliths) and fixing CO2 . It is unknown how the cells arrange different-sized coccoliths to maintain full coverage, as the cell surface area of the cell changes during daily cycle. Methods: We used Euler's polyhedron formula and CaGe simulation software, validated with the geometries of coccoliths, to analyze and simulate the coccolith topology of the coccosphere and to explore the arrangement mechanisms...
2018: PeerJ
Patricia M Valdespino-Castillo, Ping Hu, Martín Merino-Ibarra, Luz M López-Gómez, Daniel Cerqueda-García, Roberto González-De Zayas, Teresa Pi-Puig, Julio A Lestayo, Hoi-Ying Holman, Luisa I Falcón
Microbialites are modern analogs of ancient microbial consortia that date as far back as the Archaean Eon. Microbialites have contributed to the geochemical history of our planet through their diverse metabolic capacities that mediate mineral precipitation. These mineral-forming microbial assemblages accumulate major ions, trace elements and biomass from their ambient aquatic environments; their role in the resulting chemical structure of these lithifications needs clarification. We studied the biogeochemistry and microbial structure of microbialites collected from diverse locations in Mexico and in a previously undescribed microbialite in Cuba...
2018: Frontiers in Microbiology
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