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Biogeochemistry

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https://www.readbyqxmd.com/read/28096366/iron-isotopes-reveal-distinct-dissolved-iron-sources-and-pathways-in-the-intermediate-versus-deep-southern-ocean
#1
Cyril Abadie, Francois Lacan, Amandine Radic, Catherine Pradoux, Franck Poitrasson
As an essential micronutrient, iron plays a key role in oceanic biogeochemistry. It is therefore linked to the global carbon cycle and climate. Here, we report a dissolved iron (DFe) isotope section in the South Atlantic and Southern Ocean. Throughout the section, a striking DFe isotope minimum (light iron) is observed at intermediate depths (200-1,300 m), contrasting with heavier isotopic composition in deep waters. This unambiguously demonstrates distinct DFe sources and processes dominating the iron cycle in the intermediate and deep layers, a feature impossible to see with only iron concentration data largely used thus far in chemical oceanography...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28088848/mercury-bioaccumulation-in-estuarine-fishes-novel-insights-from-sulfur-stable-isotopes
#2
James J Willacker, Collin A Eagles-Smith, Joshua T Ackerman
Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ(13)C), nitrogen (δ(15)N), and sulfur (δ(34)S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the San Francisco Bay Estuary. We employed a tiered approach that first examined processes influencing variation in fish THg among wetlands, and subsequently examined the roles of habitat and within-wetland processes in generating larger-scale patterns in fish THg...
January 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28073542/the-rise-of-toxic-benthic-phormidium-proliferations-a-review-of-their-taxonomy-distribution-toxin-content-and-factors-regulating-prevalence-and-increased-severity
#3
REVIEW
Tara G McAllister, Susanna A Wood, Ian Hawes
There has been a marked increase in the distribution, intensity and frequency of proliferations of some species of the benthic mat-forming, toxin-producing genus Phormidium in rivers globally over the last decade. This review summarises current knowledge on their taxonomy, distribution, toxin content, environmental drivers of proliferations, and monitoring and management strategies in New Zealand. Although toxic Phormidium proliferation occurs in rivers worldwide little is known about these factors in most countries...
May 2016: Harmful Algae
https://www.readbyqxmd.com/read/28055128/a-decade-of-boreal-rich-fen-greenhouse-gas-fluxes-in-response-to-natural-and-experimental-water-table-variability
#4
David Olefeldt, Eugénie S Euskirchen, Jennifer Harden, Evan Kane, A David McGuire, Mark P Waldrop, Merritt R Turetsky
Rich fens are common boreal ecosystems with distinct hydrology, biogeochemistry and ecology that influence their carbon (C) balance. We present growing season soil chamber methane emission (FCH4 ), ecosystem respiration (ER), net ecosystem exchange (NEE), and gross primary production (GPP) fluxes from a nine year water table manipulation experiment in an Alaskan rich fen. The study included major flood and drought years, where wetting and drying treatments further modified the severity of droughts. Results support previous findings from peatlands that drought causes reduced magnitude of growing season FCH4 , GPP, and NEE, thus reducing or reversing their C sink function...
January 5, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28049626/estimating-monotonic-rates-from-biological-data-using-local-linear-regression
#5
Colin Olito, Craig R White, Dustin J Marshall, Diego R Barneche
Accessing many fundamental questions in biology begins with empirical estimation of simple monotonic rates of underlying biological processes. Across a variety of disciplines, ranging from physiology to biogeochemistry, these rates are routinely estimated from non-linear and noisy time series data using linear regression and ad hoc manual truncation of non-linearities. Here, we introduce the R package LoLinR, a flexible toolkit to implement local linear regression techniques to objectively and reproducibly estimate monotonic biological rates from non-linear time series data, and demonstrate possible applications using metabolic rate data...
January 3, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28008067/mass-seasonal-bioflows-of-high-flying-insect-migrants
#6
Gao Hu, Ka S Lim, Nir Horvitz, Suzanne J Clark, Don R Reynolds, Nir Sapir, Jason W Chapman
Migrating animals have an impact on ecosystems directly via influxes of predators, prey, and competitors and indirectly by vectoring nutrients, energy, and pathogens. Although linkages between vertebrate movements and ecosystem processes have been established, the effects of mass insect "bioflows" have not been described. We quantified biomass flux over the southern United Kingdom for high-flying (>150 meters) insects and show that ~3.5 trillion insects (3200 tons of biomass) migrate above the region annually...
December 23, 2016: Science
https://www.readbyqxmd.com/read/28007171/arsenic-methylation-by-an-arsenite-s-adenosylmethionine-methyltransferase-from-spirulina-platensis
#7
Yuqing Guo, Ximei Xue, Yu Yan, Yongguan Zhu, Guidi Yang, Jun Ye
Arsenic-contaminated water is a serious hazard for human health. Plankton plays a critical role in the fate and toxicity of arsenic in water by accumulation and biotransformation. Spirulina platensis (S. platensis), a typical plankton, is often used as a supplement or feed for pharmacy and aquiculture, and may introduce arsenic into the food chain, resulting in a risk to human health. However, there are few studies about how S. platensis biotransforms arsenic. In this study, we investigated arsenic biotransformation by S...
November 2016: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/27995508/spatio-temporal-variability-of-fluorescent-dissolved-organic-matter-in-the-rh%C3%A3-ne-river-delta-and-the-fos-marseille-marine-area-nw-mediterranean-sea-france
#8
Nicolas Ferretto, Marc Tedetti, Catherine Guigue, Stéphane Mounier, Patrick Raimbault, Madeleine Goutx
The spatio-temporal variability of fluorescent dissolved organic matter (FDOM) and its relationships with physical (temperature, salinity) and chemical (nutrients, chlorophyll a, dissolved and particulate organic carbon, nitrogen and phosphorus) parameters were investigated in inland waters of the Rhône River delta and the Fos-Marseille marine area (northwestern Mediterranean, France). Samples were taken approximately twice per month in two inland sites and three marine sites from February 2011 to January 2012...
December 19, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27939209/methylmercury-production-and-accumulation-in-urban-stormwater-ponds-and-habitat-wetlands
#9
R J Strickman, C P J Mitchell
Stormwater management ponds and created habitat wetlands effectively manage erosion, flooding, and pollutant loadings while providing biodiversity and aesthetic benefits, but these structures are also potential sources of methylmercury (MeHg), a bioaccumulative neurotoxin. While MeHg accumulation has been confirmed in habitat wetlands, the extent of MeHg production and accumulation in stormwater ponds is unknown. Additionally, the fine-scale spatial variation in MeHg in these wetlands has never been explored despite the possibility that cycles of wetting and drying, and the presence of aquatic plants may stimulate methylation at their margins...
February 2017: Environmental Pollution
https://www.readbyqxmd.com/read/27939094/biogeochemistry-of-trace-elements-in-the-environment-editorial-to-the-special-issue
#10
EDITORIAL
Jörg Rinklebe, Jurate Kumpiene, Gijs Du Laing, Yong-Sik Ok
No abstract text is available yet for this article.
January 15, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/27936737/field-continuous-measurement-of-dissolved-gases-with-a-cf-mims-applications-to-the-physics-and-biogeochemistry-of-groundwater-flow
#11
Eliot Chatton, Thierry Labasque, Jérôme de La Bernardie, Nicolas Guihéneuf, Olivier Bour, Luc Aquilina
In the perspective of a temporal and spatial exploration of aquatic environments (surface and groundwater), we developed a technique for field continuous measurements of dissolved gases with a precision better than 1% for N2, O2, CO2, He, Ar, 2% for Kr, 8% for Xe, and 3% for CH4, N2O and Ne. With a large resolution (from 1 × 10(-9) to 1 × 10(-2) ccSTP/g) and a capability of high frequency analysis (1 measure every 2 s), the CF-MIMS (Continuous Flow Membrane Inlet Mass Spectrometer) is an innovative tool allowing the investigation of a large panel of hydrological and biogeochemical processes in aquatic systems...
December 28, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27936127/interactions-between-thermal-acclimation-growth-rate-and-phylogeny-influence-prochlorococcus-elemental-stoichiometry
#12
Adam C Martiny, Lanying Ma, Céline Mouginot, Jeremy W Chandler, Erik R Zinser
Variability in plankton elemental requirements can be important for global ocean biogeochemistry but we currently have a limited understanding of how ocean temperature influences the plankton C/N/P ratio. Multiple studies have put forward a 'translation-compensation' hypothesis to describe the positive relationship between temperature and plankton N/P or C/P as cells should have lower demand for P-rich ribosomes and associated depressed QP when growing at higher temperature. However, temperature affects many cellular processes beyond translation with unknown outcomes on cellular elemental composition...
2016: PloS One
https://www.readbyqxmd.com/read/27918615/top-down-control-of-methane-emission-and-nitrogen-cycling-by-waterfowl
#13
R Scott Winton, Curtis J Richardson
Aquatic herbivores impose top-down control on the structure of wetland ecosystems, but the biogeochemical consequences of herbivory on methane (CH4 ) and nitrogen (N) are poorly known. To investigate the top-down effects of waterfowl on wetland biogeochemistry, we implemented exclosure experiments in a major waterfowl overwintering wetland in the southeastern United States over two growing seasons. We found that herbivory inhibited the oxidation of CH4 , leading to a mean increase in emission by 230% over control plots, and prevented nitrification, as indicated by low nitrate availability and undetectable emissions of nitrous oxide...
November 4, 2016: Ecology
https://www.readbyqxmd.com/read/27916135/integrating-chemical-imaging-of-cationic-trace-metal-solutes-and-ph-into-a-single-hydrogel-layer
#14
Christoph Hoefer, Jakob Santner, Sergey M Borisov, Walter W Wenzel, Markus Puschenreiter
Gel-based, two-dimensional (2D) chemical imaging techniques are versatile methods for investigating biogeochemically active environments at high spatial resolution (sub-mm). State-of-the-art solute imaging techniques, such as diffusive gradients in thin films (DGT) and planar optodes (PO), employ passive solute sampling or sensing. Combining these methods will provide powerful tools for studying the biogeochemistry of biological niches in soils and sediments. In this study we aimed at developing a combined single-layer gel for direct pH imaging using PO and sampling of anionic and cationic solutes by DGT, with subsequent analysis of the bound solutes by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)...
January 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/27913016/biogenic-silica-composition-and-%C3%AE-13-c-abundance-in-the-changjiang-yangtze-and-huanghe-yellow-rivers-with-implications-for-the-silicon-cycle
#15
Xiangbin Ran, Bochao Xu, Jun Liu, Chenying Zhao, Sen Liu, Jiaye Zang
The study was carried out to address a method for separation of terrestrial and marine biogenic silica (BSi) in estuaries based on BSi compositions and δ(13)C values in BSi associated organic matter (δ(13)CBSi). We used two world-class major rivers - the Changjiang (Yangtze) and Huanghe (Yellow) Rivers as examples to illustrate our approach. Our results for these rivers indicate that riverine BSi is comprised mainly of phytoliths and diatoms. River BSi concentrations vary with terrestrial inputs and in-stream primary production...
February 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/27905613/unambiguous-identification-and-discovery-of-bacterial-siderophores-by-direct-injection-21-tesla-fourier-transform-ion-cyclotron-resonance-mass-spectrometry
#16
Lawrence R Walker, Malak M Tfaily, Jared B Shaw, Nancy J Hess, Ljiljana Paša-Tolić, David W Koppenaal
Under iron-limiting conditions, bacteria produce low molecular mass Fe(iii) binding molecules known as siderophores to sequester the Fe(iii), along with other elements, increasing their bioavailability. Siderophores are thought to influence iron cycling and biogeochemistry in both marine and terrestrial ecosystems and hence the need for rapid, confident characterization of these compounds has increased. In this study, the type of siderophores produced by two marine bacterial species, Synechococcus sp. PCC 7002 and Vibrio cyclitrophicus 1F53, were characterized by use of a newly developed 21 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR MS) with direct injection electrospray ionization...
December 1, 2016: Metallomics: Integrated Biometal Science
https://www.readbyqxmd.com/read/27905445/biogeochemistry-projections-of-the-soil-carbon-deficit
#17
Eric A Davidson
No abstract text is available yet for this article.
November 30, 2016: Nature
https://www.readbyqxmd.com/read/27902405/microbial-nanowires-an-electrifying-tale
#18
Sandeep K Sure, Leigh M Ackland, Angel A Torriero, Alok Adholeya, Mandira Kochar
Electromicrobiology has gained momentum in the last ten years with advances in microbial fuel cells and the discovery of microbial nanowires (MNWs). The list of MNWs producing microorganisms is growing and providing intriguing insights into the presence of such microorganisms in diverse environments and the potential roles MNWs can perform. This review discusses the MNWs produced by different microorganisms, including their structure, composition and role in electron transfer through MNWs. Two hypotheses, metallic-like conductivity and an electron hopping model, have been proposed for electron transfer and we present a current understanding of both these hypotheses...
October 21, 2016: Microbiology
https://www.readbyqxmd.com/read/27898193/modeling-long-term-changes-in-tundra-carbon-balance-following-wildfire-climate-change-and-potential-nutrient-addition
#19
Yueyang Jiang, Edward B Rastetter, Gaius R Shaver, Adrian V Rocha, Qianlai Zhuang, Bonnie L Kwiatkowski
To investigate the underlying mechanisms that control long-term recovery of tundra carbon (C) and nutrients after fire, we employed the Multiple Element Limitation (MEL) model to simulate 200-yr post-fire changes in the biogeochemistry of three sites along a burn severity gradient in response to increases in air temperature, CO2 concentration, nitrogen (N) deposition, and phosphorus (P) weathering rates. The simulations were conducted for severely burned, moderately burned, and unburned arctic tundra. Our simulations indicated that recovery of C balance after fire was mainly determined by the internal redistribution of nutrients among ecosystem components (controlled by air temperature), rather than the supply of nutrients from external sources (e...
August 4, 2016: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/27871750/biogeochemical-and-hydrological-drivers-of-the-dynamics-of-vibrio-species-in-two-patagonian-estuaries
#20
Germán A Kopprio, M Eugenia Streitenberger, Kentaro Okuno, Mónica Baldini, Florencia Biancalana, Anna Fricke, Ana Martínez, Sucharit B Neogi, Boris P Koch, Shinji Yamasaki, Rubén J Lara
The ecology of the most relevant Vibrio species for human health and their relation to water quality and biogeochemistry were studied in two estuaries in Argentinian Patagonia. Vibrio cholerae and Vibrio parahaemolyticus were reported in >29% of cases at the Río Colorado and Río Negro estuaries. Neither the pandemic serogroups of Vibrio cholerae O1, Vibrio cholerae O139 nor the cholera toxin gene were detected in this study. However, several strains of V. cholerae (not O1 or O139) are able to cause human disease or acquire pathogenic genes by horizontal transfer...
February 1, 2017: Science of the Total Environment
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