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Gago-Ferrero P.,National and Kapodistrian University of Athens | Schymanski E.L.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Hollender J.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Hollender J.,Institute of Biogeochemistry and Pollutant Dynamics | Thomaidis N.S.,National and Kapodistrian University of Athens
Comprehensive Analytical Chemistry | Year: 2016

The existing target analytical methods described in the literature only cover a tiny fraction of the large number of compounds present in environmental samples. As a result, many potential chemical stressors are systematically omitted and there is an urgent need of analytical methodologies capable of detecting and identifying compounds using nontarget methods. In this regard, high resolution mass spectrometry coupled to liquid chromatography (LC-HRMS) has opened up new windows of opportunity for the detection of polar organic contaminants in complex samples. The objective of this chapter is to provide a critical overview of the state-of-the-art of the application of LC-HRMS to the nontarget analysis of organic contaminants in environmental samples. The existing methodologies and the different prioritisation strategies as well as workflows to characterise unknown organic pollutants are evaluated. © 2016 Elsevier B.V. Source

Ozuolmez D.,Wageningen University | Na H.,University of Vienna | Lever M.A.,Institute of Biogeochemistry and Pollutant Dynamics | Kjeldsen K.U.,University of Aarhus | And 2 more authors.
Frontiers in Microbiology | Year: 2015

Acetate is a major product of fermentation processes and an important substrate for sulfate reducing bacteria and methanogenic archaea. Most studies on acetate catabolism by sulfate reducers and methanogens have used pure cultures. Less is known about acetate conversion by mixed pure cultures and the interactions between both groups. We tested interspecies hydrogen transfer and coexistence between marine methanogens and sulfate reducers using mixed pure cultures of two types of microorganisms. First, Desulfovibrio vulgaris subsp. vulgaris (DSM 1744), a hydrogenotrophic sulfate reducer, was cocultured together with the obligate aceticlastic methanogen Methanosaeta concilii using acetate as carbon and energy source. Next, Methanococcus maripaludis S2, an obligate H2- and formate-utilizing methanogen, was used as a partner organism to M. concilii in the presence of acetate. Finally, we performed a coexistence experiment between M. concilii and an acetotrophic sulfate reducer Desulfobacter latus AcSR2. Our results showed that D. vulgaris was able to reduce sulfate and grow from hydrogen leaked by M. concilii. In the other coculture, M. maripaludis was sustained by hydrogen leaked by M. concilii as revealed by qPCR. The growth of the two aceticlastic microbes indicated co-existence rather than competition. Altogether, our results indicate that H2 leaking from M. concilii could be used by efficient H2-scavengers. This metabolic trait, revealed from coculture studies, brings new insight to the metabolic flexibility of methanogens and sulfate reducers residing in marine environments in response to changing environmental conditions and community compositions. Using dedicated physiological studies we were able to unravel the occurrence of less obvious interactions between marine methanogens and sulfate-reducing bacteria. © 2015 Ozuolmez, Na, Lever, Kjeldsen, Jørgensen and Plugge. Source

Lazzaro A.,Institute of Biogeochemistry and Pollutant Dynamics | Risse-Buhl U.,TU Brandenburg | Risse-Buhl U.,Helmholtz Center for Environmental Research | Brankatschk R.,Institute of Biogeochemistry and Pollutant Dynamics
Acta Protozoologica | Year: 2015

Phagotrophic protist diversity in oligotrophic soils such as alpine glacier forefields is still poorly studied. Combining morphologic observations with molecular-based analyses, we assessed the diversity of major phagotrophic protist groups in two contrasting glacier forefields in the Swiss Alps (Tiefen glacier forefield, siliceous bedrock, and Wildstrubel glacier forefield, calcareous bedrock), at sites differing in soil development. Ciliates and heterotrophic flagellates could be detected with both approaches, while amoebae could be observed only microscopically. Soils from Tiefen and Wildstrubel glacier forefields harboured distinctly different ciliate, flagellate and amoebae communities. The ciliate clone libraries from the Tiefen glacier forefield were dominated by Oligohymenophorea-related sequences while those from the Wildstrubel glacier forefield were dominated by Spirotrichea-related sequences. Testate amoebae morphospecies of the genera Corythion, Cryptodifflugia, Euglypha and Tracheleuglypha were restricted to the Tiefen glacier forefield, while Centropyxis and Trinema to the Wildstrubel one. No ciliate sequences and only a few ciliate and testate amoebae morphospecies could be retrieved from unvegetated soils of both glacier forefields. The ciliate and testate amoebae community detected at unvegetated sites were a subset of the community developed at vegetated sites. Overall, our results suggest that alpine glacier forefields are colonised by a diverse community of phagotrophic protists which seems to be shaped by bedrock geology and vegetation cover. © 2015, Jagiellonian University. All rights resereved. Source

Byrne D.,Institute of Biogeochemistry and Pollutant Dynamics | Byrne D.,ETH Zurich | Munnich M.,Institute of Biogeochemistry and Pollutant Dynamics | Frenger I.,Princeton University | And 3 more authors.
Nature Communications | Year: 2016

Although it is well established that the large-scale wind drives much of the world's ocean circulation, the contribution of the wind energy input at mesoscales (10-200 km) remains poorly known. Here we use regional simulations with a coupled high-resolution atmosphere-ocean model of the South Atlantic, to show that mesoscale ocean features and, in particular, eddies can be energized by their thermodynamic interactions with the atmosphere. Owing to their sea-surface temperature anomalies affecting the wind field above them, the oceanic eddies in the presence of a large-scale wind gradient provide a mesoscale conduit for the transfer of energy into the ocean. Our simulations show that this pathway is responsible for up to 10% of the kinetic energy of the oceanic mesoscale eddy field in the South Atlantic. The conditions for this pathway to inject energy directly into the mesoscale prevail over much of the Southern Ocean north of the Polar Front. Source

Mikutta C.,Institute of Biogeochemistry and Pollutant Dynamics | Mandaliev P.N.,Institute of Biogeochemistry and Pollutant Dynamics | Mahler N.,Institute of Biogeochemistry and Pollutant Dynamics | Kotsev T.,Bulgarian Academy of Science | Kretzschmar R.,Institute of Biogeochemistry and Pollutant Dynamics
Environmental Science and Technology | Year: 2014

Floodplain soils are frequently contaminated with metal(loid)s due to present or historic mining, but data on the bioaccessibility (BA) of contaminants in these periodically flooded soils are scarce. Therefore, we studied the speciation of As and Fe in eight As-contaminated circumneutral floodplain soils (≤21600 mg As/kg) and their size fractions using X-ray absorption spectroscopy (XAS) and examined the BA of As in the solids by in-vitro gastrointestinal (IVG) extractions. Arsenopyrite and As(V)-adsorbed ferrihydrite were identified by XAS as the predominant As species. The latter was the major source for bioaccessible As, which accounted for 5-35% of the total As. The amount of bioaccessible As increased with decreasing particle size and was controlled by the slow dissolution kinetics of ferrihydrite in the gastric environment (pH 1.8). The relative BA of As (% of total) decreased with decreasing particle size only in a highly As-contaminated soil - which supported by Fe XAS - suggests the formation of As-rich hydrous ferric oxides in the gastric extracts. Multiple linear regression analyses identified Al, total As, Corg, and P as main predictors for the absolute BA of As (adjusted R2 ≤ 0.977). Health risk assessments for residential adults showed that (i) nearly half of the bulk soils may cause adverse health effects and (ii) particles <5 μm pose the highest absolute health threat upon incidental soil ingestion. Owing to their low abundance, however, health risks were primarily associated with particles in the 5-50 and 100-200 μm size ranges. These particles are easily mobilized from riverbanks during flooding events and dispersed within the floodplain or transported downstream. © 2014 American Chemical Society. Source

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