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Julien Arsenault, Julie Talbot, Tim R Moore
Pools are common in northern peatlands but studies have seldom focused on their nutrient biogeochemistry, especially in relation to their morphological characteristics and through seasons. We determined the environmental characteristics controlling carbon (C), nitrogen (N) and phosphorus (P) biogeochemistry in pools and assessed their evolution over the course of the 2016 growing season in a subboreal ombrotrophic peatland of eastern Canada. We showed that water chemistry variations in 62 pools were significantly explained by depth (81...
March 12, 2018: Science of the Total Environment
Joshua D Sackett, Desiree C Huerta, Brittany R Kruger, Scott D Hamilton-Brehm, Duane P Moser
Devils Hole is the sole natural habitat of the critically endangered Devils Hole pupfish (Cyprinodon diabolis). To establish a backup population, the Ash Meadows Fish Conservation Facility (AMFCF), a full-scale replica of the uppermost 6.7 m of Devils Hole, was constructed by management agencies in the mid-2010s. Despite rigorous efforts to mimic the bathymetric and physical details of the Devils Hole environment, the biogeochemistry and microbiology of the AMFCF refuge tank remain largely unaddressed. We evaluated water physicochemistry and employed Illumina DNA sequencing of 16S rRNA gene libraries to evaluate planktonic and benthic bacterial and archaeal community composition within their respective physicochemical contexts in Devils Hole and AMFCF on the same day...
2018: PloS One
Siqi Li, Xunhua Zheng, Chunyan Liu, Zhisheng Yao, Wei Zhang, Shenghui Han
Quantifications of soil dissolvable organic carbon concentrations, together with other relevant variables, are needed to understand the carbon biogeochemistry of terrestrial ecosystems. Soil dissolvable organic carbon can generally be grouped into two incomparable categories. One is soil extractable organic carbon (EOC), which is measured by extracting with an aqueous extractant (distilled water or a salt solution). The other is soil dissolved organic carbon (DOC), which is measured by sampling soil water using tension-free lysimeters or tension samplers...
March 7, 2018: Science of the Total Environment
James C Stegen, Tim Johnson, James K Fredrickson, Michael J Wilkins, Allan E Konopka, William C Nelson, Evan V Arntzen, William B Chrisler, Rosalie K Chu, Sarah J Fansler, Emily B Graham, David W Kennedy, Charles T Resch, Malak Tfaily, John Zachara
The original version of this Article contained an error in Fig. 6e, in which the text in the legend was omitted. This has been corrected in both the PDF and HTML versions of the article.
March 7, 2018: Nature Communications
Mónica Rouco, Kyle R Frischkorn, Sheean T Haley, Harriet Alexander, Sonya T Dyhrman
The N2 -fixing cyanobacterium Trichodesmium is intensely studied because of the control this organism exerts over the cycling of carbon and nitrogen in the low nutrient ocean gyres. Although iron (Fe) and phosphorus (P) bioavailability are thought to be major drivers of Trichodesmium distributions and activities, identifying resource controls on Trichodesmium is challenging, as Fe and P are often organically complexed and their bioavailability to a single species in a mixed community is difficult to constrain...
February 28, 2018: ISME Journal
Mary R Gradoville, Byron C Crump, Claudia C Häse, Angelicque E White
Vibrio spp. have been a persistent concern for coastal bivalve hatcheries, which are vulnerable to environmental pathogens in seawater used for rearing larvae, yet the biogeochemical drivers of oyster-pathogenic Vibrio in their planktonic state are poorly understood. Here, we present data tracking oyster-pathogenic Vibrio bacteria in Netarts Bay and Yaquina Bay, Oregon, USA, as well as in adjacent coastal waters and a local shellfish hatchery, through the 2015 upwelling season. Vibrio populations were quantified using a culture-independent approach of high-throughput Vibrio -specific 16S rRNA amplicon sequencing paired with droplet digital PCR, and abundances were analyzed in the context of local biogeochemistry...
February 23, 2018: Applied and Environmental Microbiology
SungHyun Nam, Duk-Jin Kim, Seung-Woo Lee, Bong Guk Kim, Ki-Mook Kang, Yang-Ki Cho
Oceanic internal waves are known to be important to the understanding of underwater acoustics, marine biogeochemistry, submarine navigation and engineering, and the Earth's climate. In spite of the importance and increased knowledge of their ubiquity, the wave generation is still poorly understood in most parts of the world's oceans. Here, we use satellite synthetic aperture radar images, in-situ observations, and numerical models to (1) show that wave energy (having relatively high amplitude) radiates from a shallow sill in the East China Sea in all directions, but with a significant time lag dependent on background conditions, (2) reveal that wave fronts are locally formed with often favorable conditions for re-initiation, and (3) demonstrate the resulting variety of wave patterns...
February 22, 2018: Scientific Reports
Verena Schrameyer, Paul H York, Kathryn Chartrand, Peter J Ralph, Michael Kühl, Kasper Elgetti Brodersen, Michael A Rasheed
Seagrass meadows increasingly face reduced light availability as a consequence of coastal development, eutrophication, and climate-driven increases in rainfall leading to turbidity plumes. We examined the impact of reduced light on above-ground seagrass biomass and sediment biogeochemistry in tropical shallow- (∼2 m) and deep-water (∼17 m) seagrass meadows (Green Island, Australia). Artificial shading (transmitting ∼10-25% of incident solar irradiance) was applied to the shallow- and deep-water sites for up to two weeks...
February 12, 2018: Marine Environmental Research
Marc-André Cormier, Roland A Werner, Peter E Sauer, Darren R Gröcke, Markus C Leuenberger, Thomas Wieloch, Jürgen Schleucher, Ansgar Kahmen
Hydrogen (H) isotope ratio (δ2 H) analyses of plant organic compounds have been applied to assess ecohydrological processes in the environment despite a large part of the δ2 H variability observed in plant compounds not being fully elucidated. We present a conceptual biochemical model based on empirical H isotope data that we generated in two complementary experiments that clarifies a large part of the unexplained variability in the δ2 H values of plant organic compounds. The experiments demonstrate that information recorded in the δ2 H values of plant organic compounds goes beyond hydrological signals and can also contain important information on the carbon and energy metabolism of plants...
February 20, 2018: New Phytologist
E J Fleming, T Woyke, A R Donatello, M M M Kuypers, A Sczyrba, S Littmann, D Emerson
Leptothrix ochracea is known for producing large volumes of iron-oxyhydroxide sheaths that alter wetland biogeochemistry. For over a century, these delicate structures have fascinated microbiologists and geoscientists. Because L. ochracea still resists long-term in vitro culture, the debate regarding its metabolic classification dates back to 1885. We developed a novel culturing technique for L. ochracea using in situ natural waters, and coupled this with single cell genomics and nanoscale secondary ion mass spectrophotometry (nanoSIMS) to probe L...
February 16, 2018: Applied and Environmental Microbiology
Gretchen Lescord, Erik Emilson, Tom Johnston, Brian Branfireun, John Gunn
Dissolved organic matter (DOM) includes an array of carbon-based compounds that vary in size and structure and have complex interactions with mercury (Hg) cycling in aquatic systems. While many studies have examined the relationship between dissolved organic carbon concentrations ([DOC]) and methyl Hg bioaccumulation, few studies have considered the effects of DOM composition (e.g., protein-content, aromaticity). The goal of this study was to explore the relationships between total and methyl [Hg] in water, invertebrates, and fish, and optically-derived measures of DOM composition from 47 lake and river sites across a boreal watershed...
February 14, 2018: Environmental Science & Technology
Florian Reverey, Lars Ganzert, Gunnar Lischeid, Andreas Ulrich, Katrin Premke, Hans-Peter Grossart
Understanding interrelations between an environment's hydrological past and its current biogeochemistry is necessary for the assessment of biogeochemical and microbial responses to changing hydrological conditions. The question how previous dry-wet events determine the contemporary microbial and biogeochemical state is addressed in this study. Therefore, sediments exposed to the atmosphere of areas with a different hydrological past within one kettle hole, i.e. (1) the predominantly inundated pond center, (2) the pond margin frequently desiccated for longer periods and (3) an intermediate zone, were incubated with the same rewetting treatment...
February 2, 2018: Science of the Total Environment
Sanchita Mandal, Erica Donner, Sotirios Vasileiadis, William Skinner, Euan Smith, Enzo Lombi
Ammonia (NH3) volatilisation is one of the most important causes of nitrogen (N) loss in soil-plant systems worldwide. Carbon-based amendments such as biochar have been shown to mitigate NH3 volatilisation in agricultural soils to various degrees. In this study, we investigated the influence of biochar feedstocks (poultry manure, green waste compost, and wheat straw), pyrolysis temperatures (250, 350, 450, 500 and 700°C) and application rates (1 and 2%), on NH3 volatilisation from a calcareous soil. The 15 biochars were chemically characterized, and a laboratory incubation study was conducted to assess NH3 volatilisation from the soil over a period of four weeks...
February 2, 2018: Science of the Total Environment
Hugues Thouin, Fabienne Battaglia-Brunet, Marie-Paule Norini, Lydie Le Forestier, Mickael Charron, Sébastien Dupraz, Pascale Gautret
Thermal destruction of chemical munitions from World War I led to the formation of a heavily contaminated residue that contains an unexpected mineral association in which a microbial As transformation has been observed. A mesocosm study was conducted to assess the impact of water saturation episodes and input of bioavailable organic matter (OM) on pollutant behavior in relation to biogeochemical parameters. Over a period of about eight (8) months, the contaminated soil was subjected to cycles of dry and wet periods corresponding to water table level variations...
January 29, 2018: Science of the Total Environment
James C Stegen, Tim Johnson, James K Fredrickson, Michael J Wilkins, Allan E Konopka, William C Nelson, Evan V Arntzen, William B Chrisler, Rosalie K Chu, Sarah J Fansler, Emily B Graham, David W Kennedy, Charles T Resch, Malak Tfaily, John Zachara
The hyporheic corridor (HC) encompasses the river-groundwater continuum, where the mixing of groundwater (GW) with river water (RW) in the HC can stimulate biogeochemical activity. Here we propose a novel thermodynamic mechanism underlying this phenomenon and reveal broader impacts on dissolved organic carbon (DOC) and microbial ecology. We show that thermodynamically favorable DOC accumulates in GW despite lower DOC concentration, and that RW contains thermodynamically less-favorable DOC, but at higher concentrations...
February 8, 2018: Nature Communications
C T Christiansen, M J Lafreniére, G H R Henry, P Grogan
Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long-term (7-9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO2 exchange (NEE), and soil biogeochemistry in Canadian Low Arctic mesic shrub tundra.The snowfence treatment enhanced snow depth from 0.3 to ~1 m, increasing winter soil temperatures by ~3°C, but with no effect on summer soil temperature, moisture, or thaw depth...
February 7, 2018: Global Change Biology
Niloofar Karimian, Scott G Johnston, Edward D Burton
Acid sulfate soils (ASS) contain substantial quantities of iron sulfide minerals or the oxidation reaction products of these sulfidic minerals. Transformation of iron (Fe) and sulfur (S) bearing minerals is an important process in ASS wetlands with fluctuating redox conditions. A range of potentially toxic metals and metalloids can either be adsorbed on or incorporated into the structure of Fe and S bearing minerals. Therefore, transformation of these minerals as affected by dynamic redox conditions may regulate the mobility and bioavailability of associated metals/metalloids...
January 30, 2018: Chemosphere
Lipi Mukherjee, Peng-Wang Zhai, Yongxiang Hu, David M Winker
The single scattering properties of hydrosols play an important role in the study of ocean optics, ocean color remote sensing, and ocean biogeochemistry research. Measurements show that hydrosols can be of various sizes and shapes, suggesting general non-spherical models should be considered for the study of single scattering properties of hydrosols. In this work, light scattering by non-spherical hydrosols are modeled by randomly oriented spheroids with the Amsterdam discrete dipole approximation (ADDA) code...
January 22, 2018: Optics Express
Eri Kitamura, Tomonori Kotajima, Ken Sawada, Iwane Suzuki, Yoshihiro Shiraiwa
The cosmopolitan marine haptophyte alga Emiliania huxleyi accumulates very long-chain (C37-C40) alkyl ketones with two to four trans-type carbon-carbon double bonds (alkenones). These compounds are used as biomarkers of haptophytes and as palaeothermometers for estimating sea-surface temperatures in biogeochemistry. However, the biosynthetic pathway of alkenones in algal cells remains enigmatic, although it is well known that the C37 tri-unsaturated alkenone (K37:3) becomes dominant at low temperatures, either by desaturation of K37:2 or by a separate pathway involving the elongation of tri-unsaturated alkenone precursors...
February 2, 2018: Scientific Reports
R J Strickman, C P J Mitchell
Stormwater retention ponds effectively manage erosion, flooding, and pollutant loadings, but are also sources of methylmercury (MeHg), a bioaccumulative neurotoxin which is produced by anaerobic aquatic microorganisms. Stormwater retention ponds have a 10-15 year working life, after which they are dredged and reflooded. In this study, we related MeHg biogeochemistry to the different stages of the management lifecycle. In a new, a dredged, and a mature stormwater retention pond, we measured MeHg and inorganic mercury (IHg) concentrations, and the potential for MeHg formation (Kmeth), during the early summer, peak summer, and fall of 2013...
January 29, 2018: Environmental Science. Processes & Impacts
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