A unique subseafloor microbiosphere in the Mariana Trench driven by episodic sedimentation.

Unlabelled: Hadal trenches are characterized by enhanced and infrequent high-rate episodic sedimentation events that likely introduce not only labile organic carbon and key nutrients but also new microbes that significantly alter the subseafloor microbiosphere. Currently, the role of high-rate episodic sedimentation in controlling the composition of the hadal subseafloor microbiosphere is unknown. Here, analyses of carbon isotope composition in a ~ 750 cm long sediment core from the Challenger Deep revealed noncontinuous deposition, with anomalous C ages likely caused by seismically driven mass transport and the funneling effect of trench geomorphology.

Relationships between riverine and terrestrial dissolved organic carbon: Concentration, radiocarbon signature, specific UV absorbance.

The transfer of dissolved organic carbon (DOC) from land to watercourses plays a major role in the carbon cycle, and in the transport and fate of associated organic and inorganic contaminants. We investigated, at global scale, how the concentrations and properties of riverine DOC depend upon combinations of terrestrial source solutions. For topsoil, subsoil, groundwater and river solutions in different Köppen-Geiger climatic zones, we compiled published and new values of DOC concentration ([DOC]), radiocarbon signature (DOC), and specific UV absorbance (SUVA).

Proliferation of hydrocarbon-degrading microbes at the bottom of the Mariana Trench.

Background: The Mariana Trench is the deepest known site in the Earth's oceans, reaching a depth of ~ 11,000 m at the Challenger Deep. Recent studies reveal that hadal waters harbor distinctive microbial planktonic communities. However, the genetic potential of microbial communities within the hadal zone is poorly understood.

Contrasting controls on the phosphorus concentration of suspended particulate matter under baseflow and storm event conditions in agricultural headwater streams.

Whilst the processes involved in the cycling of dissolved phosphorus (P) in rivers have been extensively studied, less is known about the mechanisms controlling particulate P concentrations during small and large flows. This deficiency is addressed through an analysis of large numbers of suspended particulate matter (SPM) samples collected under baseflow (n=222) and storm event (n=721) conditions over a 23-month period across three agricultural headwater catchments of the River Wensum, UK. Relationships between clay mineral and metal oxyhydroxide associated elements were assessed and multiple linear regression models for the prediction of SPM P concentration under baseflow and storm event conditions were formulated.

Apportioning sources of organic matter in streambed sediments: an integrated molecular and compound-specific stable isotope approach.

We present a novel application for quantitatively apportioning sources of organic matter in streambed sediments via a coupled molecular and compound-specific isotope analysis (CSIA) of long-chain leaf wax n-alkane biomarkers using a Bayesian mixing model. Leaf wax extracts of 13 plant species were collected from across two environments (aquatic and terrestrial) and four plant functional types (trees, herbaceous perennials, and C3 and C4 graminoids) from the agricultural River Wensum catchment, UK. Seven isotopic (δ13C27, δ13C29, δ13C31, δ13C27-31, δ2H27, δ2H29, and δ2H27-29) and two n-alkane ratio (average chain length (ACL), carbon preference index (CPI)) fingerprints were derived, which successfully differentiated 93% of individual plant specimens by plant functional type.

The impact of environmental factors on molecular and stable isotope compositions of n-alkanes in Mediterranean extra virgin olive oils.

The impact of climatic factors on the molecular and stable carbon and hydrogen isotope compositions of n-alkanes in extra virgin olive oils from eight Mediterranean countries is studied, and the applicability of these data for olive oil regional classification is discussed. n-Alkane average chain length values are positively correlated with the amount of precipitation and are the lowest in olive oils from Morocco and Greece and the highest in oils from Spain and Portugal. Stable carbon and hydrogen isotope compositions of n-alkane C29 show significant correlation with climatic parameters and are significantly more positive in olive oils from the southern compared with northern Mediterranean countries.

The inhibitor of wax 1 locus (Iw1) prevents formation of β- and OH-β-diketones in wheat cuticular waxes and maps to a sub-cM interval on chromosome arm 2BS.

Glaucousness is described as the scattering effect of visible light from wax deposited on the cuticle of plant aerial organs. In wheat, two dominant genes lead to non-glaucous phenotypes: Inhibitor of wax 1 (Iw1) and Iw2. The molecular mechanisms and the exact extent (beyond visual assessment) by which these genes affect the composition and quantity of cuticular wax is unclear.

New on-line methods for determining the deuterium/hydrogen composition of water and hydrocarbon gases using O(2-) ion-conducting solid electrolyte reactor.

Rationale: The deuterium/hydrogen (D/H) composition of water and hydrocarbon gases is widely used in geological, environmental and petroleum studies. The aim of this work was to develop a simple reduction zirconium dioxide solid electrolyte reactor (SER) for water decomposition and new methods for measuring hydrogen isotope ratios in water and hydrocarbon gases.

Methods: δ(2)H(VSMOW) values were determined using two new different on-line methods: solid electrolyte reactor isotope ratio mass spectrometry (SER-IRMS) for water and gas chromatography combustion solid electrolyte reactor isotope ratio mass spectrometry (GC-C-SER-IRMS) for hydrocarbon gases.

Arctic hydrology during global warming at the Palaeocene/Eocene thermal maximum.

The Palaeocene/Eocene thermal maximum represents a period of rapid, extreme global warming 55 million years ago, superimposed on an already warm world. This warming is associated with a severe shoaling of the ocean calcite compensation depth and a >2.5 per mil negative carbon isotope excursion in marine and soil carbonates.

Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum.

The Palaeocene/Eocene thermal maximum, approximately 55 million years ago, was a brief period of widespread, extreme climatic warming, that was associated with massive atmospheric greenhouse gas input. Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. Here we identify the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence obtained during the Arctic Coring Expedition.