Are iron-phosphate minerals a sink for phosphorus in anoxic Black Sea sediments?

Science.gov (United States)

Dijkstra, Nikki; Kraal, Peter; Kuypers, Marcel M M; Schnetger, Bernhard; Slomp, Caroline P

2014-01-01

Phosphorus (P) is a key nutrient for marine organisms. The only long-term removal pathway for P in the marine realm is burial in sediments. Iron (Fe) bound P accounts for a significant proportion of this burial at the global scale. In sediments underlying anoxic bottom waters, burial of Fe-bound P is generally assumed to be negligible because of reductive dissolution of Fe(III) (oxyhydr)oxides and release of the associated P. However, recent work suggests that Fe-bound P is an important burial phase in euxinic (i.e. anoxic and sulfidic) basin sediments in the Baltic Sea. In this study, we investigate the role of Fe-bound P as a potential sink for P in Black Sea sediments overlain by oxic and euxinic bottom waters. Sequential P extractions performed on sediments from six multicores along two shelf-to-basin transects provide evidence for the burial of Fe-bound P at all sites, including those in the euxinic deep basin. In the latter sediments, Fe-bound P accounts for more than 20% of the total sedimentary P pool. We suggest that this P is present in the form of reduced Fe-P minerals. We hypothesize that these minerals may be formed as inclusions in sulfur-disproportionating Deltaproteobacteria. Further research is required to elucidate the exact mineral form and formation mechanism of this P burial phase, as well as its role as a sink for P in sulfide-rich marine sediments.

An open ocean record of the Toarcian oceanic anoxic event

Directory of Open Access Journals (Sweden)

D. R. Gröcke

2011-11-01

Full Text Available Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰ negative (organic carbon isotope excursion (CIE which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE. If the T-OAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (δ¹³C_org of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (>6 ‰ negative excursion in δ¹³C_org that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epi- and pericontinental strata. A smaller negative excursion in δ¹³C_org (ca. 2 ‰ is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric.

Methane oxidation in anoxic lake waters

Science.gov (United States)

Su, Guangyi; Zopfi, Jakob; Niemann, Helge; Lehmann, Moritz

2017-04-01

Freshwater habitats such as lakes are important sources of methante (CH4), however, most studies in lacustrine environments so far provided evidence for aerobic methane oxidation only, and little is known about the importance of anaerobic oxidation of CH4 (AOM) in anoxic lake waters. In marine environments, sulfate reduction coupled to AOM by archaea has been recognized as important sinks of CH4. More recently, the discorvery of anaerobic methane oxidizing denitrifying bacteria represents a novel and possible alternative AOM pathway, involving reactive nitrogen species (e.g., nitrate and nitrite) as electron acceptors in the absence of oxygen. We investigate anaerobic methane oxidation in the water column of two hydrochemically contrasting sites in Lake Lugano, Switzerland. The South Basin displays seasonal stratification, the development of a benthic nepheloid layer and anoxia during summer and fall. The North Basin is permanently stratified with anoxic conditions below 115m water depth. Both Basins accumulate seasonally (South Basin) or permanently (North Basin) large amounts of CH4 in the water column below the chemocline, providing ideal conditions for methanotrophic microorganisms. Previous work revealed a high potential for aerobic methane oxidation within the anoxic water column, but no evidence for true AOM. Here, we show depth distribution data of dissolved CH4, methane oxidation rates and nutrients at both sites. In addition, we performed high resolution phylogenetic analyses of microbial community structures and conducted radio-label incubation experiments with concentrated biomass from anoxic waters and potential alternative electron acceptor additions (nitrate, nitrite and sulfate). First results from the unamended experiments revealed maximum activity of methane oxidation below the redoxcline in both basins. While the incubation experiments neither provided clear evidence for NOx- nor sulfate-dependent AOM, the phylogenetic analysis revealed the

Previously unknown evolutionary groups dominate the ssDNA gokushoviruses in oxic and anoxic waters of a coastal marine environment

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Jessica M. Labonté

2015-04-01

Full Text Available Metagenomic studies have revealed that ssDNA phages from the family Microviridae subfamily Gokushovirinae are widespread in aquatic ecosystems. It is hypothesized that gokushoviruses occupy specialized niches, resulting in differences among genotypes traversing water column gradients. Here, we use degenerate primers that amplify a fragment of the gene encoding the major capsid protein to examine the diversity of gokushoviruses in Saanich Inlet, a seasonally anoxic fjord on the coast of Vancouver Island, British Columbia. Amplicon sequencing of samples from the mixed oxic surface (10 m and deeper anoxic (200 m layers indicated a diverse assemblage of gokushoviruses, with greater richness at 10 m than 200 m. A comparison of amplicon sequences with sequences selected on the basis of RFLP patterns from eight surface samples collected over a one-year period revealed that gokushovirus diversity was higher in spring and summer during stratification, and lower in fall and winter after deep-water renewal, consistent with seasonal variability within gokushovirus populations. Phylogenetic analysis of clustered amplicons revealed at least five new phylogenetic clades of previously unknown sequences, with the most abundant group associated with viruses that infect SUP05, a ubiquitous and abundant member of marine oxygen minimum zones. Our results provide persuasive evidence that, while specific gokushovirus genotypes may have a narrow host range, hosts for gokushoviruses in Saanich Inlet consist of a wide range of bacterial taxa, including SUP05, a taxonomic clade of gamma proteobacterial sulfur oxidizers. Members of SUP05 are abundant in Saanich Inlet and involved in carbon, nitrogen, and sulfur cycling along the redoxline; thus, gokushoviruses are likely important mortality agents of these bacteria and have consequent influences on biogeochemical cycling in this system.

Evolutionary and geologic consequences of organic carbon fixing in the primitive anoxic ocean

Science.gov (United States)

Berry, W. B. N.; Wilde, P.

1983-03-01

Steps leading to development of the modern photic-based marine food web are postulated as the result of modifications of the environment, enhanced by the activity of Archean sulfur chemoautotrophs. Such organisms (Anoxium) evolved in an anoxic ocean prior to 3.9 × 109 yr ago at Archean analogs of modern oceanic hydrothermal vents. At this time geothermal energy was more readily available to organisms than photic energy, given atmospheric conditions at the surface similar to Venus, where intensity is low and only middle and red visible wavelengths penetrate the cloudy CO2-rich atmosphere. Competition for the reduced sulfur developed due to oxidation and loss of sulfur to sediments. Consequently, evolutionary advantage shifted to Anoxium isolates that could use alternate energy sources such as light to supplement the diminished supplies of reduced sulfur. Initially, photo-sulfur organisms evolved similar to modern purple bacteria that absorb in the red visible spectra. Subsequent carbon fixing and oxidation improved both the quantity and range of light reaching the ocean surface. This permitted absorption in the blue visible range so that water splitting was now feasible, releasing free oxygen and accelerating oxidation. Eventually, reducing environments became restricted, completing the shift in the principal marine carbon-fixing activity from anoxic chemoautotrophic to aerobic photosynthetic organisms.

A marine biogeochemical perspective on black shale deposition

Science.gov (United States)

Piper, D. Z.; Calvert, S. E.

2009-06-01

Deposition of marine black shales has commonly been interpreted as having involved a high level of marine phytoplankton production that promoted high settling rates of organic matter through the water column and high burial fluxes on the seafloor or anoxic (sulfidic) water-column conditions that led to high levels of preservation of deposited organic matter, or a combination of the two processes. Here we review the hydrography and the budgets of trace metals and phytoplankton nutrients in two modern marine basins that have permanently anoxic bottom waters. This information is then used to hindcast the hydrography and biogeochemical conditions of deposition of a black shale of Late Jurassic age (the Kimmeridge Clay Formation, Yorkshire, England) from its trace metal and organic carbon content. Comparison of the modern and Jurassic sediment compositions reveals that the rate of photic zone primary productivity in the Kimmeridge Sea, based on the accumulation rate of the marine fraction of Ni, was as high as 840 g organic carbon m - 2 yr -1. This high level was possibly tied to the maximum rise of sea level during the Late Jurassic that flooded this and other continents sufficiently to allow major open-ocean boundary currents to penetrate into epeiric seas. Sites of intense upwelling of nutrient-enriched seawater would have been transferred from the continental margins, their present location, onto the continents. This global flooding event was likely responsible for deposition of organic matter-enriched sediments in other marine basins of this age, several of which today host major petroleum source rocks. Bottom-water redox conditions in the Kimmeridge Sea, deduced from the V:Mo ratio in the marine fraction of the Kimmeridge Clay Formation, varied from oxic to anoxic, but were predominantly suboxic, or denitrifying. A high settling flux of organic matter, a result of the high primary productivity, supported a high rate of bacterial respiration that led to the

Geochemical characterization and miospore biochronostratigraphy of the Frasnian anoxic event in the Parnaiba basin, Northeast Brazil

International Nuclear Information System (INIS)

Rodrigues, R.; De Melo, J.H.G.; Alves, D.B.; Loboziak, S.

1995-01-01

Radioactive shales of Frasnian age in the Parnaiba Basin present high concentrations of organic matter. They correspond to a condensed section related to the Devonian maximum marine transgression. Combined geochemical, palynological and clay mineral data point out to a dominant algal contribution in the composition of the organic matter, as well as to anoxic depositional settings. This radioactive shale interval corresponds to the onset of a long-lasting, global anoxic event which was to be intensified in the Late Frasnian, and thus can be regarded as a marker for chronostratigraphic correlations. It includes the main source rocks of Devonian age in the Palaeozoic basins of north Brazil, and therefore represents a target of potential interest for hydrocarbon exploration. (authors). 16 refs., 10 figs., 1 tab., 17 photos

Geochemical characterization and miospore biochronostratigraphy of the Frasnian anoxic event in the Parnaiba basin, Northeast Brazil

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, R.; De Melo, J.H.G.; Alves, D.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil); Loboziak, S. [Lille-1 Univ., 59 - Villeneuve-d`Ascq (France)

1995-12-31

Radioactive shales of Frasnian age in the Parnaiba Basin present high concentrations of organic matter. They correspond to a condensed section related to the Devonian maximum marine transgression. Combined geochemical, palynological and clay mineral data point out to a dominant algal contribution in the composition of the organic matter, as well as to anoxic depositional settings. This radioactive shale interval corresponds to the onset of a long-lasting, global anoxic event which was to be intensified in the Late Frasnian, and thus can be regarded as a marker for chronostratigraphic correlations. It includes the main source rocks of Devonian age in the Palaeozoic basins of north Brazil, and therefore represents a target of potential interest for hydrocarbon exploration. (authors). 16 refs., 10 figs., 1 tab., 17 photos.

Association of marine archaea with the digestive tracts of two marine fish species

NARCIS (Netherlands)

Maarel, Marc J.E.C. van der; Artz, Rebekka R.E.; Haanstra, Rene; Forney, Larry J.

Recent studies have shown that archaea which were always thought to live under strict anoxic or extreme environmental conditions are also present in cold, oxygenated seawater, soils, the digestive tract of a holothurian deep-sea-deposit feeder, and a marine sponge, In this study we show, by using

OAE2 in marine sections at high northern palaeolatitudes?

DEFF Research Database (Denmark)

Lenniger, Marc; Pedersen, Gunver Krarup; Bjerrum, Christian J.

oceanic anoxic events is the Cenomanian–Turonian boundary event (OAE2). The event is characterised by a major positive d13C excursion (ca. 2-4 ‰) in marine carbonate and both marine and terrestrial organic matter, which indicates that a major disturbance of the global carbon cycle occurred in the ocean...

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean

Directory of Open Access Journals (Sweden)

Fabián Pina-Amargós

2014-02-01

Full Text Available Marine reserves can restore fish abundance and diversity in areas impacted by overfishing, but the effectiveness of reserves in developing countries where resources for enforcement are limited, have seldom been evaluated. Here we assess whether the establishment in 1996 of the largest marine reserve in the Caribbean, Gardens of the Queen in Cuba, has had a positive effect on the abundance of commercially valuable reef fish species in relation to neighboring unprotected areas. We surveyed 25 sites, including two reef habitats (reef crest and reef slope, inside and outside the marine reserve, on five different months, and over a one-and-a-half year period. Densities of the ten most frequent, highly targeted, and relatively large fish species showed a significant variability across the archipelago for both reef habitats that depended on the month of survey. These ten species showed a tendency towards higher abundance inside the reserve in both reef habitats for most months during the study. Average fish densities pooled by protection level, however, showed that five out of these ten species were at least two-fold significantly higher inside than outside the reserve at one or both reef habitats. Supporting evidence from previously published studies in the area indicates that habitat complexity and major benthic communities were similar inside and outside the reserve, while fishing pressure appeared to be homogeneous across the archipelago before reserve establishment. Although poaching may occur within the reserve, especially at the boundaries, effective protection from fishing was the most plausible explanation for the patterns observed.

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean.

Science.gov (United States)

Pina-Amargós, Fabián; González-Sansón, Gaspar; Martín-Blanco, Félix; Valdivia, Abel

2014-01-01

Marine reserves can restore fish abundance and diversity in areas impacted by overfishing, but the effectiveness of reserves in developing countries where resources for enforcement are limited, have seldom been evaluated. Here we assess whether the establishment in 1996 of the largest marine reserve in the Caribbean, Gardens of the Queen in Cuba, has had a positive effect on the abundance of commercially valuable reef fish species in relation to neighboring unprotected areas. We surveyed 25 sites, including two reef habitats (reef crest and reef slope), inside and outside the marine reserve, on five different months, and over a one-and-a-half year period. Densities of the ten most frequent, highly targeted, and relatively large fish species showed a significant variability across the archipelago for both reef habitats that depended on the month of survey. These ten species showed a tendency towards higher abundance inside the reserve in both reef habitats for most months during the study. Average fish densities pooled by protection level, however, showed that five out of these ten species were at least two-fold significantly higher inside than outside the reserve at one or both reef habitats. Supporting evidence from previously published studies in the area indicates that habitat complexity and major benthic communities were similar inside and outside the reserve, while fishing pressure appeared to be homogeneous across the archipelago before reserve establishment. Although poaching may occur within the reserve, especially at the boundaries, effective protection from fishing was the most plausible explanation for the patterns observed.

A marine heatwave drives massive losses from the world's largest seagrass carbon stocks

Science.gov (United States)

Arias-Ortiz, A.; Serrano, O.; Masqué, P.; Lavery, P. S.; Mueller, U.; Kendrick, G. A.; Rozaimi, M.; Esteban, A.; Fourqurean, J. W.; Marbà, N.; Mateo, M. A.; Murray, K.; Rule, M. J.; Duarte, C. M.

2018-04-01

Seagrass ecosystems contain globally significant organic carbon (C) stocks. However, climate change and increasing frequency of extreme events threaten their preservation. Shark Bay, Western Australia, has the largest C stock reported for a seagrass ecosystem, containing up to 1.3% of the total C stored within the top metre of seagrass sediments worldwide. On the basis of field studies and satellite imagery, we estimate that 36% of Shark Bay's seagrass meadows were damaged following a marine heatwave in 2010/2011. Assuming that 10 to 50% of the seagrass sediment C stock was exposed to oxic conditions after disturbance, between 2 and 9 Tg CO2 could have been released to the atmosphere during the following three years, increasing emissions from land-use change in Australia by 4-21% per annum. With heatwaves predicted to increase with further climate warming, conservation of seagrass ecosystems is essential to avoid adverse feedbacks on the climate system.

Oxygen intrusion into anoxic fjords leads to increased methylmercury availability

Science.gov (United States)

Veiteberg Braaten, Hans Fredrik; Pakhomova, Svetlana; Yakushev, Evgeniy

2013-04-01

Mercury (Hg) appears in the oxic surface waters of the oceans at low levels (sub ng/L). Because inorganic Hg can be methylated into the toxic and bioaccumulative specie methylmercury (MeHg) levels can be high at the top of the marine food chain. Even though marine sea food is considered the main risk driver for MeHg exposure to people most research up to date has focused on Hg methylation processes in freshwater systems. This study identifies the mechanisms driving formation of MeHg during oxygen depletion in fjords, and shows how MeHg is made available in the surface water during oxygen intrusion. Studies of the biogeochemical structure in the water column of the Norwegian fjord Hunnbunn were performed in 2009, 2011 and 2012. In autumn of 2011 mixing flushing events were observed and lead to both positive and negative effects on the ecosystem state in the fjord. The oxygenated water intrusions lead to a decrease of the deep layer concentrations of hydrogen sulfide (H2S), ammonia and phosphate. On the other hand the intrusion also raised the H2S boundary from 8 m to a shallower depth of just 4 m. Following the intrusion was also observed an increase at shallower depths of nutrients combined with a decrease of pH. Before flushing events were observed concentrations of total Hg (TotHg) increased from 1.3 - 1.7 ng/L in the surface layer of the fjord to concentrations ranging from 5.2 ng/L to 6.4 ng/L in the anoxic zone. MeHg increased regularly from 0.04 ng/L in the surface water to a maximum concentration of 5.2 ng/L in the deeper layers. This corresponds to an amount of TotHg present as MeHg ranging from 2.1 % to 99 %. The higher concentrations of MeHg in the deeper layer corresponds to an area where no oxygen is present and concentrations of H2S exceeds 500 µM, suggesting a production of MeHg in the anoxic area as a result of sulphate reducing bacteria activity. After flushing the concentrations of TotHg showed a similar pattern ranging from 0.6 ng/L in the

Biological phosphorus uptake under anoxic and aerobic conditions

DEFF Research Database (Denmark)

Kerrn-Jespersen, Jens Peter; Henze, Mogens

1993-01-01

Biological phosphorus removal was investigated under anoxic and aerobic conditions. Tests were made to establish whether phosphorus accumulating bacteria can take up phosphate under anoxic conditions and thus utilise nitrate as oxidant. Furthermore, it was tested how the amount of organic matter...... as oxidant. The phosphorus uptake was more rapid under aerobic conditions than under anoxic conditions. The explanation of this is that all phosphorus accumulating bacteria take up phosphate under aerobic conditions, whereas only part of the phosphorus accumulating bacteria take up phosphate under anoxic...

Immobilization of metal wastes by reaction with H2S in anoxic basins: concept and elaboration.

Science.gov (United States)

Schuiling, R D

2013-10-01

Metal wastes are produced in large quantities by a number of industries. Their disposal in isolated waste deposits is certain to cause many subsequent problems, because every material will sooner or later return to the geochemical cycle. The sealing of disposal sites usually starts to leak, often within a short time after the disposal site has been filled. The contained heavy metals are leached from the waste deposit and will contaminate the soil and the groundwater. It is evident that storage as metal sulfides in a permanently anoxic environment is the only safe way to handle metal wastes. The world's largest anoxic basin, the Black Sea, can serve as a georeactor. The metal wastes are sustainably transformed into harmless and immobile solids. These are incorporated in the lifeless bottom muds, where they are stored for millions of years.

A marine heatwave drives massive losses from the world’s largest seagrass carbon stocks

KAUST Repository

Arias-Ortiz, A.

2018-03-29

Seagrass ecosystems contain globally significant organic carbon (C) stocks. However, climate change and increasing frequency of extreme events threaten their preservation. Shark Bay, Western Australia, has the largest C stock reported for a seagrass ecosystem, containing up to 1.3% of the total C stored within the top metre of seagrass sediments worldwide. On the basis of field studies and satellite imagery, we estimate that 36% of Shark Bay’s seagrass meadows were damaged following a marine heatwave in 2010/2011. Assuming that 10 to 50% of the seagrass sediment C stock was exposed to oxic conditions after disturbance, between 2 and 9 Tg CO could have been released to the atmosphere during the following three years, increasing emissions from land-use change in Australia by 4–21% per annum. With heatwaves predicted to increase with further climate warming, conservation of seagrass ecosystems is essential to avoid adverse feedbacks on the climate system.

Biogeochemical and microbiological variables measured by CTD and Niskin bottles from the Hermano Gines in the Caribbean Sea for the CARIACO Ocean Time-Series Program from 1995-11-13 to 2015-11-14 (NCEI Accession 0164194)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The goal of this project was to examine the interrelationship between microbial activity and water column geochemistry in the world’s largest, truly marine anoxic...

Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation

Science.gov (United States)

Bourke, Michael F.; Marriott, Philip J.; Glud, Ronnie N.; Hasler-Sheetal, Harald; Kamalanathan, Manoj; Beardall, John; Greening, Chris; Cook, Perran L. M.

2017-01-01

Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to bacteria and archaea. Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H2 production rates, suggesting the presence of fermentation. The production of both dissolved inorganic carbon and H2 persisted following administration of broad spectrum bactericidal antibiotics, but ceased following treatment with metronidazole. Metronidazole inhibits the ferredoxin/hydrogenase pathway of fermentative eukaryotic H2 production, suggesting that pathway as the source of H2 and dissolved inorganic carbon production. Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae. Cell counts revealed a predominance of microalgae in the sediments. H2 production was observed in dark anoxic cultures of diatoms (Fragilariopsis sp.) and a chlorophyte (Pyramimonas) isolated from the study site, substantiating the hypothesis that microalgae undertake fermentation. We conclude that microalgal dark fermentation could be an important energy-conserving pathway in permeable sediments.

Uranium(IV) adsorption by natural organic matter in anoxic sediments

Energy Technology Data Exchange (ETDEWEB)

Bone, Sharon E.; Dynes, James; Cliff, John B.; Barger, John

2017-01-09

Uranium is an important fuel source and a global environmental contaminant. It accumulates in the tetravalent state, U(IV), in anoxic sediments, including ore deposits, marine basins, and contaminated aquifers. However, very little is known about the speciation of U(IV) in low temperature geochemical environments, inhibiting the development of a conceptual model of U behavior. Until recently, U(IV) was assumed to exist predominantly as the sparingly soluble mineral uraninite (UO₂) in anoxic sediments; yet studies now show that UO₂ is not often dominant in these environments. However, a model of U(IV) speciation under environmentally relevant conditions has not yet been developed. Here we show that complexes of U(IV) adsorb on organic carbon and organic carbon-coated clays in an organic-rich natural substrate under field-relevant conditions. Whereas previous research assumed that the U(IV) product depended on the reduction pathway, our results demonstrate that UO₂ formation can be inhibited simply by decreasing the U:solid ratio. Thus, it is the number and type of surface ligands that controls U(IV) speciation subsequent to U(VI) reduction. Projections of U transport and bioavailability, and thus its threat to human and ecosystem health, must consider retention of U(IV) ions within the local sediment environment.

Fallout plutonium in two oxic-anoxic environments

International Nuclear Information System (INIS)

Sanchez, A.L.; Murray, J.W.; Schell, W.R.; Miller, L.G.

1986-01-01

The profiles of soluble fallout plutonium in two partially anoxic waters revealed minimum concentrations at the O 2 -H 2 S interface, indicating Pu removal onto particulate phases of Fe and other oxidized species that form during the redox cycle. In Saanich Inlet, an intermittently anoxic fjord in Vancouver Island, Canada, the concentration of soluble Pu in the anoxic zone was slightly less than in the oxygenated surface layer. In Soap Lake, a saline meromictic lake in eastern Washington State, Pu concentrations i the permanently anoxic zone were at least an order of magnitude higher than at the surface. Differences in the chemical characteristics of these two waters suggest important chemical species that influenced the observed Pu distribution. In the permanently anoxic zone of Soap Lake, high values of total alkalinity ranging from 940 to 1500 meq liter -1 , sulfide species from 38 to 128 μM, dissolved organic carbon from 163 to 237 mg liter -1 , and total dissolved solids from 80 to 140 ppt, all correlated with the observed high concentration of Pu. In Saanich Inlet, where total alkalinity ranged from 2.1 to 2.4 meq liter -1 and salinity from 25 to 32 per thousand and H 2 S concentration in May 1981 showed a maximum of 8μM, the observed Pu concentrations were significantly lower than for the Soap Lake monimolimnion

Single neuron dynamics during experimentally induced anoxic depolarization

NARCIS (Netherlands)

Zandt, B.; Stigen, Tyler; ten Haken, Bernard; Netoff, Theoden; van Putten, Michel Johannes Antonius Maria

2013-01-01

We studied single neuron dynamics during anoxic depolarizations, which are often observed in cases of neuronal energy depletion. Anoxic and similar depolarizations play an important role in several pathologies, notably stroke, migraine, and epilepsy. One of the effects of energy depletion was

Studies of anoxiC conditions in Framvaren fjord, Gullmaren fjord and Byfjorden and of mixing between seawater and freshwater at the Kalix river and estuary

International Nuclear Information System (INIS)

Roos, P.

2001-01-01

The sediments in the anoxic Framvaren fjord acts as a source for actinides to the overlaying water column. The remobilisation process is most likely linked to early diagenetic alteration of the marine organic material in the sediments. This is indicated by the close correlation between Pu, Am and dissolved organic carbon depth profiles in the water column. Speciation studies of the plutonium and americium in the water column shows that both to a large degree are associated to colloidal material in the size range 0.01-0.45 μm. Less than 2% is retained by a 0.45 μm filter which is reflected in the low K D -values obtained of about 20 000, which is at least a factor of 10 lower than in typical coastal waters. It is also proven that the plutonium exist almost entirely in the trivalent state in the anoxic water column. This study is the first ever to show extensive remobilisation of plutonium and americium from sediments in anoxic marine basins. Similar remobilisation from sediments most likely occur in other anoxic marine waters where early diagenesis results in humic and fulvic acid production. Although the remobilised actinides in the Framvaren fjord at present don't pose any radiological hazard due to the lack of fish in anoxic waters, it is of great concern to identify processes involved in the remobilisation of actinides from anoxic sediments as such sediments likely will be a major source for actinides in the Baltic Sea and other oxygen sensitive basins in the long term perspective. In such basins the remobilised plutonium may reach oxygenated and biological productive waters by convection. Results from the temporarily oxygen deficient Gullmaren fjord on the Swedish west coast shows that remobilisation from sediments can not be identified during short (a few months) periods of oxygen deficient water. The rapid bioturbation (quantified by tracer studies) in this fjord results in that sedimenting organic material rapidly is buried and distributed within the upper

Studies of anoxiC conditions in Framvaren fjord, Gullmaren fjord and Byfjorden and of mixing between seawater and freshwater at the Kalix river and estuary

Energy Technology Data Exchange (ETDEWEB)

Roos, P. [Univ. of Lund, Lund (Sweden)

2001-04-01

The sediments in the anoxic Framvaren fjord acts as a source for actinides to the overlaying water column. The remobilisation process is most likely linked to early diagenetic alteration of the marine organic material in the sediments. This is indicated by the close correlation between Pu, Am and dissolved organic carbon depth profiles in the water column. Speciation studies of the plutonium and americium in the water column shows that both to a large degree are associated to colloidal material in the size range 0.01-0.45 {mu}m. Less than 2% is retained by a 0.45 {mu}m filter which is reflected in the low K{sub D}-values obtained of about 20 000, which is at least a factor of 10 lower than in typical coastal waters. It is also proven that the plutonium exist almost entirely in the trivalent state in the anoxic water column. This study is the first ever to show extensive remobilisation of plutonium and americium from sediments in anoxic marine basins. Similar remobilisation from sediments most likely occur in other anoxic marine waters where early diagenesis results in humic and fulvic acid production. Although the remobilised actinides in the Framvaren fjord at present don't pose any radiological hazard due to the lack of fish in anoxic waters, it is of great concern to identify processes involved in the remobilisation of actinides from anoxic sediments as such sediments likely will be a major source for actinides in the Baltic Sea and other oxygen sensitive basins in the long term perspective. In such basins the remobilised plutonium may reach oxygenated and biological productive waters by convection. Results from the temporarily oxygen deficient Gullmaren fjord on the Swedish west coast shows that remobilisation from sediments can not be identified during short (a few months) periods of oxygen deficient water. The rapid bioturbation (quantified by tracer studies) in this fjord results in that sedimenting organic material rapidly is buried and distributed

Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation

DEFF Research Database (Denmark)

Bourke, Michael F.; Marriott, Philip J.; Glud, Ronnie N.

2017-01-01

Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to prokaryotes such as bacteria and archaea....... Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H....../hydrogenase pathway of fermentative eukaryotic H2 production, suggesting that pathway as the source of H2 and dissolved inorganic carbon production. Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae...

Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

Science.gov (United States)

Alperin, M. J.; Blair, Neal E.; Albert, D. B.; Hoehler, T. M.; Martens, C. S.

1993-01-01

The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from 'noncompetitive' substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 per thousand. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in C-13, reaching a maximum delta(C-13) value of -42 per thousand. Third, the acetate pool experienced a precipitous decline from greater than 5 mM to less than 20 micro-M and methane production was again dominated by CO2 reduction. The delta(C-13) of methane produced during this final phase ranged from -46 to -58 per thousand. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8 percent of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane

The behavior of scavenged isotopes in marine anoxic environments: 210Pb and 210Po in the water column of the Black Sea

International Nuclear Information System (INIS)

Wei, C.L.; Murray, J.W.

1994-01-01

Vertical profiles of dissolved and particulate 210 Pb and 210 Po were determined at two stations in the Black Sea in June 1988. Vertical fluxes of 210 Pb and 210 Po were also measured in the upper 150 m, using floating sediment traps. The fractionation of 210 Pb between dissolved and particulate phases in the Black Sea is strongly influenced by the redox conditions in the water column. Dissolved 210 Pb dominates in the oxic zone, while particulate 210 Pb is the major form in the deep sulfide-rich anoxic zone. The distribution of 210 Pb across the suboxic zone appears to be mainly controlled by redox cycling of manganese and iron. In the sulfide-rich layer coprecipitation of lead with iron sulfide is probably the dominant scavenging mechanism. A simple scavenging model was used to calculate the residence times of dissolved and particulate 210 Pb in the oxic, suboxic, and anoxic zones. The residence times of dissolved 210 Pb relative to scavenging by particles are 0.5-1, 2-3, and 3.5 years in the oxic, suboxic, and anoxic layers, respectively. The corresponding residence times of particulate 210 Pb relative to particle removal processes in the same layers are 0.1, 1.5-2.5, and 8.5 years, respectively. A particle settling velocity of about 40 m y -1 was derived from the 210 Pb/ 226 Ra disequilibrium in the deep Black Sea. The relatively short residence times of 210 Pb support the hypothesis that anoxic basins are important sites for boundary scavenging of 210 Pb. The 210 Po profiles indicate that biological rather than inorganic particles are the major carrier phases for Po in the Black sea. Based on the magnitude of distribution coefficients, the relative partitioning of Pb, Po, and Th to particles found in the oxic and anoxic layers of the Black Sea are Po > Th > Pb and Po = Pb > Th, respectively. Colloidal phases may be important for the scavenging of these radionuclides

Ether lipids of planktonic archae in the marine water column

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Hoefs, M.J.L.; Schouten, S.; King, L.L.; Wakeham, S.G.; Leeuw, J.W. de

1997-01-01

Acyclic and cyclic biphytanes derived from the membrane ether lipids of archaea were found in water column particulate and sedimentary organic matter from several oxic and anoxic marine environments. Compound-specific isotope analyses of the carbon skeletons suggest that planktonic archaea utilize

The first metazoa living in permanently anoxic conditions

Directory of Open Access Journals (Sweden)

Heiner Iben

2010-04-01

Full Text Available Abstract Background Several unicellular organisms (prokaryotes and protozoa can live under permanently anoxic conditions. Although a few metazoans can survive temporarily in the absence of oxygen, it is believed that multi-cellular organisms cannot spend their entire life cycle without free oxygen. Deep seas include some of the most extreme ecosystems on Earth, such as the deep hypersaline anoxic basins of the Mediterranean Sea. These are permanently anoxic systems inhabited by a huge and partly unexplored microbial biodiversity. Results During the last ten years three oceanographic expeditions were conducted to search for the presence of living fauna in the sediments of the deep anoxic hypersaline L'Atalante basin (Mediterranean Sea. We report here that the sediments of the L'Atalante basin are inhabited by three species of the animal phylum Loricifera (Spinoloricus nov. sp., Rugiloricus nov. sp. and Pliciloricus nov. sp. new to science. Using radioactive tracers, biochemical analyses, quantitative X-ray microanalysis and infrared spectroscopy, scanning and transmission electron microscopy observations on ultra-sections, we provide evidence that these organisms are metabolically active and show specific adaptations to the extreme conditions of the deep basin, such as the lack of mitochondria, and a large number of hydrogenosome-like organelles, associated with endosymbiotic prokaryotes. Conclusions This is the first evidence of a metazoan life cycle that is spent entirely in permanently anoxic sediments. Our findings allow us also to conclude that these metazoans live under anoxic conditions through an obligate anaerobic metabolism that is similar to that demonstrated so far only for unicellular eukaryotes. The discovery of these life forms opens new perspectives for the study of metazoan life in habitats lacking molecular oxygen.

Chromium isotope composition of reducing and anoxic sediments from the Peru Margin and Cariaco Basin

Science.gov (United States)

Gueguen, B.; Planavsky, N.; Wang, X.; Algeo, T. J.; Peterson, L. C.; Reinhard, C. T.

2014-12-01

Chromium isotope systematics in marine sediments are now being used as a new redox proxy of the modern and ancient Earth's surface. Chromium is primarily delivered to the oceans by riverine inputs through weathering of Cr(III)-rich minerals present in the continental crust and oxidation of insoluble Cr(III) to soluble Cr(VI) species. Since oxidation-reduction reactions fractionate Cr isotopes whereby oxidized Cr(VI) species are preferentially enriched in heavy Cr isotopes, the Cr isotope composition of marine sediments may be useful tracers of redox conditions at the Earth's surface through geological time. Chromium is quantitatively removed in organic-rich sediments where reducing conditions prevail and promote reduction of Cr(VI) to Cr(III), and thus, these sediments should capture the ambient seawater Cr isotope composition. However, the isotopic composition of modern organic-rich sediments is poorly documented so far, and this step is essential for further modeling the global oceanic Cr isotope mass balance and assessing the effects of sedimentation and post-depositional processes on the marine Cr isotopes archive. In this study, we have characterized modern marine organic-rich sediments for their Cr isotope composition (δ53/52Cr) from two different settings, the Peru margin upwelling zone and the anoxic Cariaco Basin (Venezuela). Chromium isotopes were measured on a MC-ICP-MS (Nu Plasma) using a double-spike correction method. The authigenic fraction of shallow samples from the Peru margin sedimentary sequence with a high Total Organic Carbon (TOC) content (>10 wt%) yield an average δ53/52Crauthigenic value of +0.67 ±0.05 ‰ (2sd). However, although this value is close to the seawater value (Atlantic Ocean) and to Cariaco basin sediments (~ +0.6 ‰), reducing sediments from the Peru margin are on average isotopically slightly heavier, especially in samples having a low authigenic fraction and a low TOC content (δ53/52Crauthigenic values up to +1.30 �

The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela

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José Alejandro Méndez Dot

Full Text Available ABSTRACTCarbonates of Cogollo Group (Apón, Lisure and Maraca formations constitute the broader calcareous platform system originated during Aptian and Albian of Cretaceous in north-western South America, Maracaibo Basin, Venezuela. On the shallow shelf, a variety of calcareous sedimentary facies were deposited during marine transgressive and regressive cycles. Some of them developed porosity and constitute important hydrocarbon reservoirs. Due to some major marine transgressions, from early Aptian, the anoxic environment and characteristic facies of a pelagic environment moved from the outer slope and basin to the shallow shelf, during specific time intervals, favouring the sedimentation of organic matter-rich facies, which correspond to the oceanic anoxic events (OAEs 1a and 1b. The source rock of Machiques Member (Apón Formation was deposited during early Aptian OAE 1a (~ 120 Ma. The source rock of Piché Member, located at the top of the Apón Formation, was deposited during late Aptian OAE 1b (~ 113 Ma. Finally, La Luna Formation, from Cenomanian, that covers the OAE 2 (~ 93 Ma, represents the most important source rock in the Maracaibo Basin. In this way and based on sedimentological and organic geochemistry results from the determinations performed on 247 samples belonging to six cores in the Maracaibo Basin, we propose these two organic-rich levels, deposited on the shallow shelf of the Cogollo Group, as "effective source rocks", additional to La Luna Formation, with oil migration in relatively small distances to the porosity facies.

Management of Reflex Anoxic Seizures

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J Gordon Millichap

2013-10-01

Full Text Available Investigators at the Roald Dahl EEG Unit, Alder Hey Children’s NHS Foundation, Liverpool, UK, review the definition, pathophysiology, clinical presentation, and management of reflex anoxic seizures (RAS in children.

Photochemical synthesis of biomolecules under anoxic conditions

Science.gov (United States)

Folsome, C.; Brittain, A.; Zelko, M.

1983-01-01

The long-wavelength UV anoxic photosynthesis of uracil, various sugars (including deoxyribose and glycoaldehyde), amino acids, and other organic photoproducts is reported. The reactions were conducted in a mixture of water, calcium carbonate, hydrazine, and formaldehyde which were subjected to 24 hr or 72 hr radiation. Product yields were greatest when the hydrazine/formaldehyde ratio was one, and when the reactant concentrations were low. These data suggest that organic products can be formed in variety from those amounts of formaldehyde and hydazine precursors which are themselves formed under anoxic UV photochemical conditions.

Long distance electron transmission in marine sediment

DEFF Research Database (Denmark)

Risgaard-Petersen, Nils; Nielsen, Lars Peter

processes leads to formation of electrical fields, which modifies ion transport. The local proton producing and proton consuming half reactions induces pH extremes that accelerate dissolution of iron sul-phides and calcium carbonates in anoxic layers and promotes the formation of Mg-calcite and iron oxides......Geochemical observations in marine sediment have recently shown that electric currents may intimately couple spatially separated biogeochemical processes like oxygen reduction at the sediment surface and hydrogen sul-phide oxidation in anoxic layers centimeters below 1. Further experimental studies...... suggest that the electron conductance is mediated by microorgan-isms. The spatial separation of electron and proton donors and acceptors has major impacts on element cycling by redox processes, pH balances, mineral dissolution/precipitations, and electromigration of ions. The sepa-ration of redox...

Uranium and plutonium in anoxic marine sediments of the Santiago River mouth (Eastern Pacific, Mexico).

Science.gov (United States)

Almazán-Torres, María Guadalupe; Ordóñez-Regil, Eduardo; Ruiz-Fernández, Ana Carolina

2016-11-01

The uranium (U) and plutonium (Pu) content with depth in a sediment core collected in the continental shelf off the mouth of the Santiago River in the Mexican Pacific was studied to evaluate the contamination effects of the effluent of the Santiago-Lerma River as it moves into the sea. The large mass of terrestrial detritus delivered by the river influences the physicochemical and geochemical processes in the seafloor. Abnormal concentrations of U and Pu in sediments were examined as indicative of the effects of anoxic conditions. One of the indicators of pollution of seawater is the bacterial activity of the shallow seabed layer; and among the prevailing bacteria, the magnetotactic ones induce the formation of euhedral and framboidal shapes (pyrite). These pyrite entities are by-products of anoxic environments loaded with decomposing detrital material and are very abundant in the surface layers of the sediment core analyzed. The pyrite formation is the result of a biochemical reaction between iron and organic sulphur reduced by bacteria, and the pyrite entities precipitate to the seafloor. In the same upper zone of the profile, 238 U is readily immobilized, while 234 U is oxidized and dissolved in seawater by the effect of hot atom chemistry. This may cause the activity ratio (AR) 234 U/ 238 U disequilibrium (near 0.41). Furthermore, in the shallow layer of the sediment core, an abnormally high concentration of 239+240 Pu was detected. In this upper layer, the activity concentrations found were 3.19 Bq kg -1 for 238 U, 1.32 kg -1 for 234 U and 2.78 Bq kg -1 for 239+240 Pu. In the lower fractions of the sediment core, normal values of AR 234 U/ 238 U (≈1) were found, with traces of 239+240 Pu. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polyphosphates as a source of enhanced P fluxes in marine sediments overlain by anoxic waters: Evidence from 31P NMR

Directory of Open Access Journals (Sweden)

Ingall Ellery

2005-06-01

Full Text Available Sedimentary phosphorus (P composition was investigated in Effingham Inlet, a fjord located on the west coast of Vancouver Island in Barkley Sound. Solid-state 31P nuclear magnetic resonance (NMR spectroscopy was applied to demineralized sediment samples from sites overlain by oxic and anoxic bottom waters. The two sites were similar in terms of key diagenetic parameters, including the mass accumulation rate, integrated sulfate reduction rate, and bulk sediment organic carbon content. In contrast, P benthic fluxes were much higher at the anoxic site. 31P NMR results show that P esters and phosphonates are the major organic P species present at the surface and at depth in sediments at both sites. Polyphosphates were only found in the surface sediment of the site overlain by oxic waters. The varying stability of polyphosphates in microorganisms under different redox conditions may, in part, explain their distribution as well as differences in P flux between the two sites.

Role of chemolithoautotrophic microorganisms involved in nitrogen and sulfur cycling in coastal marine sediments

NARCIS (Netherlands)

Lipsewers, Y.A.

2017-01-01

SummaryThe role of chemolithoautotrophic microorganisms has been considered to be of minor importancein coastal marine sediments although it has not been investigated in depth. Additionally,the impact of seasonal hypoxic/anoxic conditions on microbial chemolithoautotrophy in coastalmarine sediments

Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

Science.gov (United States)

Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

2016-11-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

Flourishing ocean drives the end-Permian marine mass extinction.

Science.gov (United States)

Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas; Strauss, Harald; Korn, Dieter; Korte, Christoph

2015-08-18

The end-Permian mass extinction, the most severe biotic crisis in the Phanerozoic, was accompanied by climate change and expansion of oceanic anoxic zones. The partitioning of sulfur among different exogenic reservoirs by biological and physical processes was of importance for this biodiversity crisis, but the exact role of bioessential sulfur in the mass extinction is still unclear. Here we show that globally increased production of organic matter affected the seawater sulfate sulfur and oxygen isotope signature that has been recorded in carbonate rock spanning the Permian-Triassic boundary. A bifurcating temporal trend is observed for the strata spanning the marine mass extinction with carbonate-associated sulfate sulfur and oxygen isotope excursions toward decreased and increased values, respectively. By coupling these results to a box model, we show that increased marine productivity and successive enhanced microbial sulfate reduction is the most likely scenario to explain these temporal trends. The new data demonstrate that worldwide expansion of euxinic and anoxic zones are symptoms of increased biological carbon recycling in the marine realm initiated by global warming. The spatial distribution of sulfidic water column conditions in shallow seafloor environments is dictated by the severity and geographic patterns of nutrient fluxes and serves as an adequate model to explain the scale of the marine biodiversity crisis. Our results provide evidence that the major biodiversity crises in Earth's history do not necessarily implicate an ocean stripped of (most) life but rather the demise of certain eukaryotic organisms, leading to a decline in species richness.

Bioturbation: impact on the marine nitrogen cycle.

Science.gov (United States)

Laverock, Bonnie; Gilbert, Jack A; Tait, Karen; Osborn, A Mark; Widdicombe, Steve

2011-01-01

Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significantly affect these microbial processes by altering the physicochemical properties of the sediment. For example, the building and irrigation of burrows by bioturbators introduces fresh oxygenated water into deeper sediment layers and allows the exchange of solutes between the sediment and water column. Burrows can effectively extend the oxic/anoxic interface into deeper sediment layers, thus providing a unique environment for nitrogen-cycling microbial communities. Recent studies have shown that the abundance and diversity of micro-organisms can be far greater in burrow wall sediment than in the surrounding surface or subsurface sediment; meanwhile, bioturbated sediment supports higher rates of coupled nitrification-denitrification reactions and increased fluxes of ammonium to the water column. In the present paper we discuss the potential for bioturbation to significantly affect marine nitrogen cycling, as well as the molecular techniques used to study microbial nitrogen cycling communities and directions for future study.

Tracking Early Jurassic marine (de)oxygenation

Science.gov (United States)

Them, T. R., II; Caruthers, A. H.; Gill, B. C.; Gröcke, D. R.; Marroquín, S. M.; Owens, J. D.

2017-12-01

It has been suggested that the carbon cycle was perturbed during the Toarcian OAE (T-OAE) as observed in the carbon isotope record, and more recently other elemental cycles (e.g., Hg, Mo, Os, S). The most widely accepted hypothesis focuses on the emplacement of the Karoo-Ferrar large igneous province, outgassing of greenhouse gases, and subsequent feedbacks in the Earth system, which caused severe environmental change and biological turnover. Feedbacks to elevated atmospheric pCO2 include enhanced weathering rates, dissociation of methane clathrates, increased terrestrial methanogenesis, and widespread marine anoxia. The sequence of events related to the development and duration of marine anoxia are not well constrained for this time interval due to a lack of open-ocean geochemical records. In order to reconstruct the timing of marine deoxygenation during the Early Jurassic T-OAE, we have utilized thallium isotopes, a novel geochemical proxy from multiple anoxic basins in North America and Germany. Three sites representing a basin transect from the Western Canada Sedimentary Basin, and one site from the South German Basin, were chosen to reconstruct the thallium isotopic composition (ɛ205Tl) of the ocean. The ɛ205Tl composition of sediments deposited under anoxic and euxinic water columns records the global seawater ɛ205Tl composition, a function of the amount of manganese oxides that are precipitated. Increased geographic extent of marine anoxia will cause a decrease in manganese oxide precipitation and perturb the thallium system. Importantly, the inputs of thallium are nearly identical, thus changes in these fluxes cannot drive the observed perturbation. Our new Early Jurassic ɛ205Tl records suggest that the onset of marine deoxygenation occurred concurrently with Karoo-Ferrar magmatism in the late Pliensbachian and continued until after the T-OAE. These new data support a Karoo-Ferrar trigger of the T-OAE. However, thallium isotopes also suggest that

Acid azo dye remediation in anoxic-aerobic-anoxic microenvironment under periodic discontinuous batch operation: bio-electro kinetics and microbial inventory.

Science.gov (United States)

Venkata Mohan, S; Suresh Babu, P; Naresh, K; Velvizhi, G; Madamwar, Datta

2012-09-01

Functional behavior of anoxic-aerobic-anoxic microenvironment on azo dye (C.I. Acid black 10B) degradation was evaluated in a periodic discontinuous batch mode operation for 26 cycles. Dye removal efficiency and azo-reductase activity (30.50 ± 1 U) increased with each feeding event until 13th cycle and further stabilized. Dehydrogenase activity also increased gradually and stabilized (2.0 ± 0.2 μg/ml) indicating the stable proton shuttling between metabolic intermediates providing higher number of reducing equivalents towards dye degradation. Voltammetric profiles showed drop in redox catalytic currents during stabilized phase also supports the consumption of reducing equivalents towards dye removal. Change in Tafel slopes, polarization resistance and other bioprocess parameters correlated well with the observed dye removal and biocatalyst behavior. Microbial community analysis documented the involvement of specific organism pertaining to aerobic and facultative functions with heterotrophic and autotrophic metabolism. Integrating anoxic microenvironment with aerobic operation might have facilitated effective dye mineralization due to the possibility of combining redox functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mechanisms of browning development in aggregates of marine organic matter formed under anoxic conditions: A study by mid-infrared and near-infrared spectroscopy

Science.gov (United States)

Mecozzi, Mauro; Acquistucci, Rita; Nisini, Laura; Conti, Marcelo Enrique

2014-03-01

In this paper we analyze some chemical aspects concerning the browning development associated to the aggregation of marine organic matter (MOM) occurring in anoxic conditions. Organic matter samples obtained by the degradation of different algal samples were daily taken to follow the evolution of the aggregation process and the associated browning process. These samples were examined by Fourier transform mid infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopy and the colour changes occurring during the above mentioned aggregation process were measured by means of Colour Indices (CIs). Spectral Cross Correlation Analysis (SCCA) was applied to correlate changes in CI values to the structural changes of MOM observed by FTIR and FTNIR spectra which were also submitted to Two-Dimensional Hetero Correlation Analysis (2HDCORR). SCCA results showed that all biomolecules present in MOM aggregates such as carbohydrates, proteins and lipids are involved in the browning development. In particular, SCCA results of algal mixtures suggest that the observed yellow-brown colour can be linked to the development of non enzymatic (i.e. Maillard) browning reactions. SCCA results for MOM furthermore suggest that aggregates coming from brown algae also showed evidence of browning related to enzymatic reactions. In the end 2HDCORR results indicate that hydrogen bond interactions among different molecules of MOM can play a significant role in the browning development.

Anoxic denitrification of BTEX: Biodegradation kinetics and pollutant interactions.

Science.gov (United States)

Carvajal, Andrea; Akmirza, Ilker; Navia, Daniel; Pérez, Rebeca; Muñoz, Raúl; Lebrero, Raquel

2018-05-15

Anoxic mineralization of BTEX represents a promising alternative for their abatement from O 2 -deprived emissions. However, the kinetics of anoxic BTEX biodegradation and the interactions underlying the treatment of BTEX mixtures are still unknown. An activated sludge inoculum was used for the anoxic abatement of single, dual and quaternary BTEX mixtures, being acclimated prior performing the biodegradation kinetic tests. The Monod model and a Modified Gompertz model were then used for the estimation of the biodegradation kinetic parameters. Results showed that both toluene and ethylbenzene are readily biodegradable under anoxic conditions, whereas the accumulation of toxic metabolites resulted in partial xylene and benzene degradation when present both as single components or in mixtures. Moreover, the supplementation of an additional pollutant always resulted in an inhibitory competition, with xylene inducing the highest degree of inhibition. The Modified Gompertz model provided an accurate fitting for the experimental data for single and dual substrate experiments, satisfactorily representing the antagonistic pollutant interactions. Finally, microbial analysis suggested that the degradation of the most biodegradable compounds required a lower microbial specialization and diversity, while the presence of the recalcitrant compounds resulted in the selection of a specific group of microorganisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

A carbon isotope budget for an anoxic marine sediment

International Nuclear Information System (INIS)

Boehme, S.E.; Blair, N.E.

1991-01-01

A carbon isotope budget has been determined for the coastal marine site, Cape Lookout Bight, NC. Isotope measurements of methane and σCO 2 fluxing out and buried in these sediments were applied to previously measured flux data (Martens et al., in press) to predict the isotopic composition of the incoming metabolizable organic matter. Methane leaves the sediment predominantly via ebullition with an isotopic composition of -60 per mil. Less than 2% of the methane produced is buried with an average diffusional flux value of -17 per mil and a burial value of +11 per mil. The isotope budget predicts a metabolizable organic carbon isotope signature of -19.3 per mil which is in excellent agreement with the measured total organic carbon value of -19.2 ± 0.3 per mil implying that the dominant remineralization processes have been identified

The Microworld of Marine-Bacteria

DEFF Research Database (Denmark)

JØRGENSEN, BB

1995-01-01

Microsensor studies show that the marine environment in the size scale of bacteria is physically and chemically very different from the macroenvironment. The microbial world of the sediment-water interface is thus dominated by water viscosity and steep diffusion gradients. Because of the diverse...... metabolism types, bacteria in the mostly anoxic sea floor play an important role in the major element cycles of the ocean. The communities of giant, filamentous sulfur bacteria that live in the deep-sea hydrothermal vents or along the Pacific coast of South America are presented here as examples....

Autotrophic and heterotrophic nitrification-anoxic denitrification dominated the anoxic/oxic sewage treatment process during optimization for higher loading rate and energy savings.

Science.gov (United States)

Zhang, Xueyu; Zheng, Shaokui; Zhang, Hangyu; Duan, Shoupeng

2018-04-30

This study clarified the dominant nitrogen (N)-transformation pathway and the key ammonia-oxidizing microbial species at three loading levels during optimization of the anoxic/oxic (A/O) process for sewage treatment. Comprehensive N-transformation activity analysis showed that ammonia oxidization was performed predominantly by aerobic chemolithotrophic and heterotrophic ammonia oxidization, whereas N 2 production was performed primarily by anoxic denitrification in the anoxic unit. The abundances of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria, and anaerobic AOB in activated sludge reflected their activities on the basis of high-throughput sequencing data. AOB amoA gene clone libraries revealed that the predominant AOB species in sludge samples shifted from Nitrosomonas europaea (61% at the normal loading level) to Nitrosomonas oligotropha (58% and 81% at the two higher loading levels). Following isolation and sequencing, the predominant culturable heterotrophic AOB in sludge shifted from Agrobacterium tumefaciens (42% at the normal loading level) to Acinetobacter johnsonii (52% at the highest loading level). Copyright © 2018 Elsevier Ltd. All rights reserved.

Culture-Dependent and Independent Studies of Microbial Diversity in Highly Copper-Contaminated Chilean Marine Sediments

NARCIS (Netherlands)

Besaury, L.; Marty, F.; Buquet, S.; Mesnage, V.; Muijzer, G.; Quillet, L.

2013-01-01

Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions,

Sulfur Isotope Exchange between S-35 Labeled Inorganic Sulfur-Compounds in Anoxic Marine-Sediments

DEFF Research Database (Denmark)

FOSSING, H.; THODEANDERSEN, S.; JØRGENSEN, BB

1992-01-01

Isotope exchange reactions between S-35-labeled sulfur compounds were studied in anoxic estuarine sediment slurries at 21-degrees-C and pH 7.4-7.7. Two experiments labeled with radioactive elemental sulfur (S-35-degrees) and one labeled with radioactive sulfate ((SO42-)-S-35) were performed as time......% of the total S-35 was recovered in the SIGMA-HS- pool in less than 1.5 h. With no detectable SIGMA-HS- (less than 1-mu-M) in the slurry, 58% of the total S-35 was observed in the pyrite pool within 1.5 h. The FeS pool received up to 31% of all S-35 added. The rapid S-35 incorporation from S-35-degrees...... into SIGMA-HS- and FeS pools was explained by isotope exchange reactions. In contrast, there was evidence that the radioactivity observed in the 'pyrite pool' was caused by adhesion of the added S-35-degrees to the FeS2 grains. In all S-35-degrees-labeled experiments we also observed oxidation...

An Updated View of the Microbial Diversity in Deep Hypersaline Anoxic Basins

KAUST Repository

Mapelli, Francesca

2017-03-02

Deep hypersaline anoxic basins (DHABs) are marine extreme habitats, firstly discovered in the 1970s of the last century, located in several oceanographic regions, including the Mediterranean and Red Sea and the Gulf of Mexico. These basins are filled with brines that do not mix with the overlying seawater, due to a density difference. Brine and seawater result separated by a thick interface acting as a trap for particulate and cells. Some microbiological studies focused on seawater-brine interfaces of DHABs, showing that microbial populations are differentially distributed according to the gradient of salinity, oxygen, and nutrients occurring in such transition zones. Moreover, DHABs’ brines were intensively studied showing that specific bacterial, archaeal, and eukaryotic populations thrive there. In the last few years, cultivation and “omics”-based approaches have been used with samples collected from DHABs around the world, allowing clarifying metabolic processes of paramount ecological importance and pointing out the high biotechnological potential of the inhabiting extremophiles.

Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

Science.gov (United States)

Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction.

The global marine phosphorus cycle: Response to climate change and feedbacks on ocean biogeochemistry. Geologica Ultraiectina (329)

NARCIS (Netherlands)

Tsandev, I.

2010-01-01

This thesis focuses on the marine phosphorus (P) cycle and its response to changing environmental conditions, particularly those associated with glacial-interglacial cycles of the late Pleistocene and Ocean Anoxic Events in the Cretaceous. From a box model of the ocean phosphorus, organic carbon and

Survival and Recovery of Methanotrophic Bacteria Starved Under Oxic and Anoxic Conditions

Science.gov (United States)

Roslev, Peter; King, Gary M.

1994-01-01

The effects of carbon deprivation on survival of methanotrophic bacteria were compared in cultures incubated in the presence and absence of oxygen in the starvation medium. Survival and recovery of the examined methanotrophs were generally highest for cultures starved under anoxic conditions as indicated by poststarvation measurements of methane oxidation, tetrazolium salt reduction, plate counts, and protein synthesis. Methylosinus trichosporium OB3b survived up to 6 weeks of carbon deprivation under anoxic conditions while maintaining a physiological state that allowed relatively rapid (hours) methane oxidation after substrate addition. A small fraction of cells starved under oxic and anoxic conditions (4 and 10%, respectively) survived more than 10 weeks but required several days for recovery on plates and in liquid medium. A non-spore-forming methanotroph, strain WP 12, displayed 36 to 118% of its initial methane oxidation capacity after 5 days of carbon deprivation. Oxidation rates varied with growth history prior to the experiments as well as with starvation conditions. Strain WP 12 starved under anoxic conditions showed up to 90% higher methane oxidation activity and 46% higher protein production after starvation than did cultures starved under oxic conditions. Only minor changes in biomass and niorpholow were seen for methanotrophic bacteria starved tinder anoxic conditions. In contrast, starvation under oxic conditions resulted in morphology changes and an initial 28 to 35% loss of cell protein. These data suggest that methanotrophic bacteria can survin,e carbon deprivation under anoxic conditions by using maintenance energy derived Solelyr from an anaerobic endogenous metabolism. This capability could partly explain a significant potential for methane oxidation in environments not continuously, supporting aerobic methanotrophic growth.

Meta-omic signatures of microbial metal and nitrogen cycling in marine oxygen minimum zones

Directory of Open Access Journals (Sweden)

Jennifer B. Glass

2015-09-01

Full Text Available Iron (Fe and copper (Cu are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO3-, NO2-, Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metagenomes and 9 metatranscriptomes from Eastern Tropical North and South Pacific oxygen minimum zones and 7 metagenomes from the Bermuda Atlantic Time-series Station. Dissolved Fe concentrations increased sharply at upper oxic-anoxic transition zones, with the highest Fe:Cu molar ratio (1.8 occurring at the anoxic core of the Eastern Tropical North Pacific oxygen minimum zone and matching the predicted maximum ratio based on data from diverse ocean sites. The relative abundance of genes encoding Fe-binding proteins was negatively correlated with O2, driven by significant increases in genes encoding Fe-proteins involved in dissimilatory nitrogen metabolisms under anoxia. Transcripts encoding cytochrome c oxidase, the Fe- and Cu-containing terminal reductase in aerobic respiration, were positively correlated with O2 content. A comparison of the taxonomy of genes encoding Fe- and Cu-binding vs. bulk proteins in OMZs revealed that Planctomycetes represented a higher percentage of Fe genes while Thaumarchaeota represented a higher percentage of Cu genes, particularly at oxyclines. These results are broadly consistent with higher relative abundance of genes encoding Fe-proteins in the genome of a marine planctomycete vs. higher relative abundance of genes encoding Cu-proteins in the genome of a marine thaumarchaeote. These findings highlight the importance of metalloenzymes for microbial processes in oxygen minimum zones and suggest preferential Cu use in oxic habitats with Cu > Fe vs. preferential Fe use in anoxic niches with Fe > Cu.

Archaeal remains dominate marine organic matter from the early Albian oceanic anoxic event 1b

DEFF Research Database (Denmark)

Kuypers, M.M.M.; Blokker, P.; Hopmans, E.C.

2002-01-01

The sources for both soluble and insoluble organic matter of the early Albian (∼112 Myr) oceanic anoxic event (OAE) 1b black shales of the Ocean Drilling Program (ODP) site 1049C (North Atlantic Ocean off the coast of Florida) and the Ravel section of the Southeast France Basin (SEFB) were...... in C/C ratios was used to estimate that up to ∼40% of the organic matter of the SEFB and up to ∼80% of the organic matter of ODP site 1049C preserved in the black shales is derived from archaea. Furthermore, it is shown that, even though there are apparent similarities (high organic carbon (OC) content......, distinct lamination, C-enrichment of OC) between the black shales of OAE1b and the Cenomanian/Turonian (∼94 Myr) OAE, the origin of the organic matter (archaeal versus phytoplanktonic) and causes for C-enrichment of OC are completely different....

Reefs and islands of the Chagos Archipelago, Indian Ocean: why it is the world’s largest no-take marine protected area

Science.gov (United States)

SHEPPARD, C. R. C.; ATEWEBERHAN, M.; BOWEN, B. W.; CARR, P.; CHEN, C. A.; CLUBBE, C.; CRAIG, M. T.; EBINGHAUS, R.; EBLE, J.; FITZSIMMONS, N.; GAITHER, M. R.; GAN, C-H.; GOLLOCK, M.; GUZMAN, N.; GRAHAM, N. A. J.; HARRIS, A.; JONES, R.; KESHAVMURTHY, S.; KOLDEWEY, H.; LUNDIN, C. G.; MORTIMER, J. A.; OBURA, D.; PFEIFFER, M.; PRICE, A. R. G.; PURKIS, S.; RAINES, P.; READMAN, J. W.; RIEGL, B.; ROGERS, A.; SCHLEYER, M.; SEAWARD, M. R. D; SHEPPARD, A. L. S.; TAMELANDER, J.; TURNER, J. R.; VISRAM, S.; VOGLER, C.; VOGT, S.; WOLSCHKE, H.; YANG, J. M-C.; YANG, S-Y.; YESSON, C.

2014-01-01

The Chagos Archipelago was designated a no-take marine protected area (MPA) in 2010; it covers 550 000 km2, with more than 60 000 km2 shallow limestone platform and reefs. This has doubled the global cover of such MPAs.It contains 25–50% of the Indian Ocean reef area remaining in excellent condition, as well as the world’s largest contiguous undamaged reef area. It has suffered from warming episodes, but after the most severe mortality event of 1998, coral cover was restored after 10 years.Coral reef fishes are orders of magnitude more abundant than in other Indian Ocean locations, regardless of whether the latter are fished or protected.Coral diseases are extremely low, and no invasive marine species are known.Genetically, Chagos marine species are part of the Western Indian Ocean, and Chagos serves as a ‘stepping-stone’ in the ocean.The no-take MPA extends to the 200 nm boundary, and. includes 86 unfished seamounts and 243 deep knolls as well as encompassing important pelagic species.On the larger islands, native plants, coconut crabs, bird and turtle colonies were largely destroyed in plantation times, but several smaller islands are in relatively undamaged state.There are now 10 ‘important bird areas’, coconut crab density is high and numbers of green and hawksbill turtles are recovering.Diego Garcia atoll contains a military facility; this atoll contains one Ramsar site and several ‘strict nature reserves’. Pollutant monitoring shows it to be the least polluted inhabited atoll in the world. Today, strict environmental regulations are enforced.Shoreline erosion is significant in many places. Its economic cost in the inhabited part of Diego Garcia is very high, but all islands are vulnerable.Chagos is ideally situated for several monitoring programmes, and use is increasingly being made of the archipelago for this purpose. PMID:25505830

Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

DEFF Research Database (Denmark)

Arnosti, Carol; Finke, Niko; Larsen, Ole

2005-01-01

of activity that it fueled, its soluble nature, and its relatively high (50%) carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity to react rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar to observations made......Complex substrates are degraded in anoxic sediments by the concerted activities of diverse microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently cold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high...... which they were derived. Although Spirulina and Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate content), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbon was respired, despite the initial burst...

Microbial oceanography of anoxic oxygen minimum zones

DEFF Research Database (Denmark)

Ulloa, Osvaldo; Canfield, Donald E; DeLong, Edward F

2012-01-01

oxide (N(2)O) gases. Anaerobic microbial processes, including the two pathways of N(2) production, denitrification and anaerobic ammonium oxidation, are oxygen-sensitive, with some occurring only under strictly anoxic conditions. The detection limit of the usual method (Winkler titrations) for measuring...

A model for microbial phosphorus cycling in bioturbated marine sediments

DEFF Research Database (Denmark)

Dale, Andrew W.; Boyle, R. A.; Lenton, Timothy M.

2016-01-01

A diagenetic model is used to simulate the diagenesis and burial of particulate organic carbon (Corg) and phosphorus (P) in marine sediments underlying anoxic versus oxic bottom waters. The latter are physically mixed by animals moving through the surface sediment (bioturbation) and ventilated...... P pump) allows preferential mineralization of the bulk Porg pool relative to Corg during both aerobic and anaerobic respiration and is consistent with the database. Results with this model show that P burial is strongly enhanced in sediments hosting fauna. Animals mix highly labile Porg away from....... The results also help to explain Corg:Porg ratios in the geological record and the persistence of Porg in ancient marine sediments. © 2016 Elsevier Ltd....

Microbial Oxidation of Pyrite Coupled to Nitrate Reduction in Anoxic Groundwater Sediment

DEFF Research Database (Denmark)

Jørgensen, Christian Juncher; Elberling, Bo; Jacobsen, Ole Stig

2009-01-01

denitrification process with pyrite as the primary electron donor. The process demonstrates a temperature dependency (Q10) of 1.8 and could be completely inhibited by addition of a bactericide (NaN3). Experimentally determined denitrification rates show that more than 50% of the observed nitrate reduction can...... be ascribed to pyrite oxidation. The apparent zero-order denitrification rate in anoxic pyrite containing sediment at groundwater temperature has been determined to be 2-3 µmol NO3- kg-1 day-1. The in situ groundwater chemistry at the boundary between the redoxcline and the anoxic zone reveals that between 65......-anoxic boundary in sandy aquifers thus determining the position and downward progression of the redox boundary between nitrate-containing and nitrate-free groundwater....

Marine Mammal and Sea Turtle Research Collection (MMASTR)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Southwest Fisheries Science Center in La Jolla houses one of the largest marine mammal and marine turtle sample collections in the world, with over 140,000...

Reassessment of anoxic storage of ethnographic rubber

DEFF Research Database (Denmark)

Shashoua, Yvonne; Dyer, Joanne; Ward, Clare

2011-01-01

This paper revisits the 1991–1995 British Museum field trial on anoxic storage, where 23 registered ethnographic rubber objects were enclosed in oxygen barrier film Cryovac BDF200 with sachets of the oxygen absorbent Ageless Z. A unique opportunity for study was presented since most of the enclos...

Microbially mediated barite dissolution in anoxic brines

International Nuclear Information System (INIS)

Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren; Renock, Devon

2017-01-01

Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO_4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO_4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic

Contaminant removal performances on domestic sewage using modified anoxic/anaerobic/oxic process and micro-electrolysis.

Science.gov (United States)

Zhou, Jun; Gao, Jingqing; Liu, Yifan; Xiao, Shuai; Zhang, Ruiqin; Zhang, Zhenya

2013-01-01

The objective of this study was to enhance removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) from domestic sewage in a sequencing batch reactor with added new materials. A modified anoxic/anaerobic/oxic (MAAO) process, integrating a micro-electrolysis (ME) bed in an anoxic tank, and complex biological media (CBM) in anoxic, anaerobic and oxic tanks to treat domestic sewage, and their performances were investigated. The MAAO system was operated at controlled hydraulic retention time (HRT) of 8 h and mixed liquor recirculation (MLR) at 75%. The results showed that the MAAO system could effectively remove COD, TN and TP with average rates of 93%, 80% and 94%, respectively, in March, and 94%, 76% and 91%, respectively, in August. In this system, TP was primarily removed from the anoxic tank regardless of the operational conditions; removal contribution ratios to TP of the anoxic tank reached 56% both in March and August, indicating that the ME bed can effectively enhance phosphorus removal. TN was primarily removed from the anoxic and anaerobic tanks; removal contribution ratios to TN of anoxic and anaerobic tanks reached 36-38% and 37-38%, respectively. The oxic tank had the highest share of COD removal (56% both in March and August) in the removal of phosphorus. The outflow concentrations of COD, TN and TP were 3-46, 7-14 and 0.3-0.5 mg/L, respectively, in March, and 26-49, 9-15 and 0.04-0.1 mg/L, respectively, in August. COD and TN removal performances indicated that the innovative materials of the ME bed and CBM can effectively enhance COD and TN removal.

High bacterial biodiversity increases degradation performance of hydrocarbons during bioremediation of contaminated harbor marine sediments

International Nuclear Information System (INIS)

Dell'Anno, Antonio; Beolchini, Francesca; Rocchetti, Laura; Luna, Gian Marco; Danovaro, Roberto

2012-01-01

We investigated changes of bacterial abundance and biodiversity during bioremediation experiments carried out on oxic and anoxic marine harbor sediments contaminated with hydrocarbons. Oxic sediments, supplied with inorganic nutrients, were incubated in aerobic conditions at 20 °C and 35 °C for 30 days, whereas anoxic sediments, amended with organic substrates, were incubated in anaerobic conditions at the same temperatures for 60 days. Results reported here indicate that temperature exerted the main effect on bacterial abundance, diversity and assemblage composition. At higher temperature bacterial diversity and evenness increased significantly in aerobic conditions, whilst decreased in anaerobic conditions. In both aerobic and anaerobic conditions, biodegradation efficiencies of hydrocarbons were significantly and positively related with bacterial richness and evenness. Overall results presented here suggest that bioremediation strategies, which can sustain high levels of bacterial diversity rather than the selection of specific taxa, may significantly increase the efficiency of hydrocarbon degradation in contaminated marine sediments. - Highlights: ► Bioremediation performance was investigated on hydrocarbon contaminated sediments. ► Major changes in bacterial diversity and assemblage composition were observed. ► Temperature exerted the major effect on bacterial assemblages. ► High bacterial diversity increased significantly biodegradation performance. ► This should be considered for sediment remediation by bio-treatments. - Bioremediation strategies which can sustain high levels of bacterial diversity may significantly increase the biodegradation of hydrocarbons in contaminated marine sediments.

MRI demonstration of cortical laminar necrosis and delayed white matter injury in anoxic encephalopathy

International Nuclear Information System (INIS)

Sawada, H.; Udaka, F.; Seriu, N.; Shindou, K.; Kameyama, M.; Tsujimura, M.

1990-01-01

We performed serial radiological examinations on a patient with anoxic encephalopathy. In the early term after the anoxic insult, T1-weighted MRI revealed high signal intensity area distributed laminarly in the cerebral cortex and diffusely in the putamen, which were thought to refect the cortical necrosis and necrosis in the putamen. Single photon emission computed tomography using I-123 isopropylamphetamine showed persistent hypoperfusion in the arterial watershed zones. T2-weighted MRI performed several months after the anoxic episode revealed diffuse high-intensity lesions in the arterial watershed zones. These delayed-onset white matter lesions continued to extend over several months. (orig.)

Multiple episodes of extensive marine anoxia linked to global warming and continental weathering following the latest Permian mass extinction.

Science.gov (United States)

Zhang, Feifei; Romaniello, Stephen J; Algeo, Thomas J; Lau, Kimberly V; Clapham, Matthew E; Richoz, Sylvain; Herrmann, Achim D; Smith, Harrison; Horacek, Micha; Anbar, Ariel D

2018-04-01

Explaining the ~5-million-year delay in marine biotic recovery following the latest Permian mass extinction, the largest biotic crisis of the Phanerozoic, is a fundamental challenge for both geological and biological sciences. Ocean redox perturbations may have played a critical role in this delayed recovery. However, the lack of quantitative constraints on the details of Early Triassic oceanic anoxia (for example, time, duration, and extent) leaves the links between oceanic conditions and the delayed biotic recovery ambiguous. We report high-resolution U-isotope (δ 238 U) data from carbonates of the uppermost Permian to lowermost Middle Triassic Zal section (Iran) to characterize the timing and global extent of ocean redox variation during the Early Triassic. Our δ 238 U record reveals multiple negative shifts during the Early Triassic. Isotope mass-balance modeling suggests that the global area of anoxic seafloor expanded substantially in the Early Triassic, peaking during the latest Permian to mid-Griesbachian, the late Griesbachian to mid-Dienerian, the Smithian-Spathian transition, and the Early/Middle Triassic transition. Comparisons of the U-, C-, and Sr-isotope records with a modeled seawater PO 4 3- concentration curve for the Early Triassic suggest that elevated marine productivity and enhanced oceanic stratification were likely the immediate causes of expanded oceanic anoxia. The patterns of redox variation documented by the U-isotope record show a good first-order correspondence to peaks in ammonoid extinctions during the Early Triassic. Our results indicate that multiple oscillations in oceanic anoxia modulated the recovery of marine ecosystems following the latest Permian mass extinction.

Uranium isotope evidence for an expansion of marine anoxia during the end-Triassic extinction

Science.gov (United States)

Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas; Lau, Kimberly V.; Weaver, Karrie L.; Maher, Kate; Payne, Jonathan L.

2017-08-01

The end-Triassic extinction coincided with an increase in marine black shale deposition and biomarkers for photic zone euxinia, suggesting that anoxia played a role in suppressing marine biodiversity. However, global changes in ocean anoxia are difficult to quantify using proxies for local anoxia. Uranium isotopes (δ238U) in CaCO3 sediments deposited under locally well-oxygenated bottom waters can passively track seawater δ238U, which is sensitive to the global areal extent of seafloor anoxia due to preferential reduction of 238U(VI) relative to 235U(VI) in anoxic marine sediments. We measured δ238U in shallow-marine limestones from two stratigraphic sections in the Lombardy Basin, northern Italy, spanning over 400 m. We observe a ˜0.7‰ negative excursion in δ238U beginning in the lowermost Jurassic, coeval with the onset of the initial negative δ13C excursion and persisting for the duration of subsequent high δ13C values in the lower-middle Hettangian stage. The δ238U excursion cannot be realistically explained by local mixing of uranium in primary marine carbonate and reduced authigenic uranium. Based on output from a forward model of the uranium cycle, the excursion is consistent with a 40-100-fold increase in the extent of anoxic deposition occurring worldwide. Additionally, relatively constant uranium concentrations point toward increased uranium delivery to the oceans from continental weathering, which is consistent with weathering-induced eutrophication following the rapid increase in pCO2 during emplacement of the Central Atlantic Magmatic Province. The relative timing and duration of the excursion in δ238U implies that anoxia could have delayed biotic recovery well into the Hettangian stage.

Physiology, Fe(II oxidation, and Fe mineral formation by a marine planktonic cyanobacterium grown under ferruginous conditions

Directory of Open Access Journals (Sweden)

Elizabeth D. Swanner

2015-10-01

Full Text Available Evidence for Fe(II oxidation and deposition of Fe(III-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF. While the exact mechanisms of Fe(II oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II-rich waters in terms of growth, Fe uptake and homeostasis, and Fe mineral formation. We therefore grew the common marine cyanobacterium Synechococcus PCC 7002 in closed bottles that began anoxic, and contained Fe(II concentrations that span the range of possible concentrations in Precambrian seawater. These results, along with cell suspension experiments, indicate that Fe(II is likely oxidized by this strain via chemical oxidation with oxygen produced during photosynthesis, and not via any direct enzymatic or photosynthetic pathway. Imaging of the cell-mineral aggregates with scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM are consistent with extracellular precipitation of Fe(III (oxyhydroxide minerals, but that >10% of Fe(III sorbs to cell surfaces rather than precipitating. Proteomic experiments support the role of reactive oxygen species (ROS in Fe(II toxicity to Synechococcus PCC 7002. The proteome expressed under low Fe conditions included multiple siderophore biosynthesis and siderophore and Fe transporter proteins, but most siderophores are not expressed during growth with Fe(II. These results provide a mechanistic and quantitative framework for evaluating the geochemical consequences of perhaps life’s greatest metabolic innovation, i.e. the evolution and activity of oxygenic photosynthesis, in ferruginous

Increased thermohaline stratification as a possible cause for an ocean anoxic event in the Cretaceous period.

Science.gov (United States)

Erbacher, J; Huber, B T; Norris, R D; Markey, M

2001-01-18

Ocean anoxic events were periods of high carbon burial that led to drawdown of atmospheric carbon dioxide, lowering of bottom-water oxygen concentrations and, in many cases, significant biological extinction. Most ocean anoxic events are thought to be caused by high productivity and export of carbon from surface waters which is then preserved in organic-rich sediments, known as black shales. But the factors that triggered some of these events remain uncertain. Here we present stable isotope data from a mid-Cretaceous ocean anoxic event that occurred 112 Myr ago, and that point to increased thermohaline stratification as the probable cause. Ocean anoxic event 1b is associated with an increase in surface-water temperatures and runoff that led to decreased bottom-water formation and elevated carbon burial in the restricted basins of the western Tethys and North Atlantic. This event is in many ways similar to that which led to the more recent Plio-Pleistocene Mediterranean sapropels, but the greater geographical extent and longer duration (approximately 46 kyr) of ocean anoxic event 1b suggest that processes leading to such ocean anoxic events in the North Atlantic and western Tethys were able to act over a much larger region, and sequester far more carbon, than any of the Quaternary sapropels.

QTL Analysis of Anoxic Tolerance at Seedling Stage in Rice

Directory of Open Access Journals (Sweden)

Yang WANG

2010-09-01

Full Text Available Coleoptile lengths of 7-day-old seedlings under anoxic stress and normal conditions were investigated in two permanently segregated populations and their parents in rice (Oryza sativa L.. Using anoxic response index, a ratio of coleoptile length under anoxic stress to coleoptile length under normal conditions, as an indicator of seedling anoxic tolerance (SAT, QTLs for SAT were detected. Two loci controlling SAT, designated as qSAT-2-R and qSAT-7-R, were detected in a recombinant inbred line (RIL population (247 lines derived from a cross between Xiushui 79 (japonica variety and C Bao (japonica restorer line. qSAT-2-R, explaining 8.7% of the phenotype variation, was tightly linked with the SSR marker RM525. qSAT-7-R, explaining 9.8% of the phenotype variation, was tightly linked with the marker RM418. The positive alleles of the two loci came from C Bao. Six loci controlling SAT, designated as qSAT-2-B, qSAT-3-B, qSAT-5-B, qSAT-8-B, qSAT-9-B and qSAT-12-B, were detected in a backcross inbred line (BIL population (98 lines derived from a backcross of Nipponbare (japonica/Kasalath (indica//Nipponbare (japonica. The positive alleles of qSAT-2-B, qSAT-3-B and qSAT-9-B, which explained 16.2%, 11.4% and 9.5% of the phenotype variation, respectively, came from Nipponbare. Besides, the positive alleles of qSAT-5-B, qSAT-8-B and qSAT-12-B, which explained 7.3%, 5.8% and 14.0% of the phenotype variation, respectively, were from Kasalath.

Organic geochemistry of the early Toarcian oceanic anoxic event in Hawsker Bottoms, Yorkshire, England

Science.gov (United States)

French, K. L.; Sepúlveda, J.; Trabucho-Alexandre, J.; Gröcke, D. R.; Summons, R. E.

2014-03-01

A comprehensive organic geochemical investigation of the Hawsker Bottoms outcrop section in Yorkshire, England has provided new insights about environmental conditions leading into and during the Toarcian oceanic anoxic event (T-OAE; ∼183 Ma). Rock-Eval and molecular analyses demonstrate that the section is uniformly within the early oil window. Hydrogen index (HI), organic petrography, polycyclic aromatic hydrocarbon (PAH) distributions, and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the T-OAE and across a lithological transition. Unlike other ancient intervals of anoxia and extinction, biomarker indices of planktonic community structure do not display major changes or anomalous values. Depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the T-OAE. In addition to carotenoid biomarkers for green sulfur bacteria (GSB), we report the first occurrence of okenane, a marker of purple sulfur bacteria (PSB), in marine samples younger than ∼1.64 Ga. Based on modern observations, a planktonic source of okenane's precursor, okenone, would require extremely shallow photic zone euxinia (PZE) and a highly restricted depositional environment. However, due to coastal vertical mixing, the lack of planktonic okenone production in modern marine sulfidic environments, and building evidence of okenone production in mat-dwelling Chromatiaceae, we propose a sedimentary source of okenone as an alternative. Lastly, we report the first parallel compound-specific δC13 record in marine- and terrestrial-derived biomarkers across the T-OAE. The δC13 records of short-chain n-alkanes, acyclic isoprenoids, and long-chain n-alkanes all encode negative carbon isotope excursions (CIEs), and together, they support an injection of isotopically light

Benthic fluxes of mercury during redox changes in pristine coastal marine sediments from the Gulf of Trieste (northern Adriatic Sea)

Energy Technology Data Exchange (ETDEWEB)

Koron, Neza [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Faganeli, Jadran [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences

2012-12-15

Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxygen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methods: Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stages: oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that in the oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hypothesis that MeHg desorption from reduced metal hydroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, represent areas with a risk of high benthic release of

Does a strong pycnocline impact organic-matter preservation and accumulation in an anoxic setting? The case of the Orca Basin, Gulf of Mexico

Science.gov (United States)

Tribovillard, Nicolas; Bout-Roumazeilles, Viviane; Sionneau, Thomas; Serrano, Jean Carlos Montero; Riboulleau, Armelle; Baudin, François

2009-01-01

The Orca Basin (an intraslope depression located in the Gulf of Mexico) collects sedimentary particles of terrestrial origin (clastic and organic particles mainly supplied by the Mississippi River) and of marine origin (biogenic productivity). The basin is partly filled with dense brines leached from salt diapirs cropping out on the sea floor, and is permanently stratified. A strong pycnocline induces anoxic bottom conditions, expectedly favorable to organic matter (OM) preservation. Here, we report on OM in the upper 750 cm below sea floor of Core MD02-2552 (Holocene). The organic content is dominated by marine-derived amorphous OM. The organic assemblage is unexpectedly degraded to some extent, which may be accounted for by a relatively long residence time of organic particles at the halocline-pycnocline at ˜2240 m. Thus the organic particles are temporarily trapped and kept in contact with the dissolved oxygen-rich overlying water mass. Lastly, the land-derived organic fraction shows co-variations with the land-derived clay mineral supply.

Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

DEFF Research Database (Denmark)

Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V.

2014-01-01

The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are re......The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid...... caused massive organic-carbon burial on the Arctic shelf in general, with important implications for hydrocarbon source-rock distribution in the Arctic region....

Apparent Minimum Free Energy Requirements for Methanogenic Archaea and Sulfate-Reducing Bacteria in an Anoxic Marine Sediment

Science.gov (United States)

Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Martens, Christopher S.; DeVincenzi, Don (Technical Monitor)

2000-01-01

Among the most fundamental constraints governing the distribution of microorganisms in the environment is the availability of chemical energy at biologically useful levels. To assess the minimum free energy yield that can support microbial metabolism in situ, we examined the thermodynamics of H2-consuming processes in anoxic sediments from Cape Lookout Bight, NC, USA. Depth distributions of H2 partial pressure, along with a suite of relevant concentration data, were determined in sediment cores collected in November (at 14.5 C) and August (at 27 C) and used to calculate free energy yields for methanogenesis and sulfate reduction. At both times of year, and for both processes, free energy yields gradually decreased (became less negative) with depth before reaching an apparent asymptote. Sulfate reducing bacteria exhibited an asymptote of -19.1 +/- 1.7 kj(mol SO4(2-)(sup -1) while methanogenic archaea were apparently supported by energy yields as small as -10.6 +/- 0.7 kj(mol CH4)(sup -1).

Natural attenuation potential of phenylarsenicals in anoxic groundwaters.

Science.gov (United States)

Hempel, Michael; Daus, Birgit; Vogt, Carsten; Weiss, Holger

2009-09-15

The extensive production of chemical warfare agents in the 20th century has led to serious contamination of soil and groundwater with phenyl arsenicals at former ammunition depots or warfare agent production sites worldwide. Most phenyl arsenicals are highly toxic for humans. The microbial degradation of phenylarsonic acid (PAA) and diphenylarsinic acid (DPAA) was investigated in microcosms made of anoxic groundwater/sediment mixtures taken from different depths of an anoxic, phenyl arsenical contaminated aquifer in Central Germany. DPAA was not transformed within 91 days incubation time in any of the microcosms. The removal of PAA can be described by a first order kinetics without a lag-phase (rate: 0.037 d(-1)). In sterilized microcosms, PAA concentrations always remained stable, demonstrating that PAA transformation was a biologically mediated process. PAA transformation occurred under sulfate-reducing conditions due to sulfate consumption and production of sulfide. The addition of lactate (1 mM), a typical substrate of sulfate-reducing bacteria, increased the transformation rate of PAA significantly up to 0.134 d(-1). The content of total arsenic was considerably reduced (> 75%). Intermediates of PAA transformation were detected by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Experiments with a pure strain and sterile controls of Desulfovibrio gigas spiked with PAA showed that the elimination process is linked to the presence of sulfide formed through bacterial activity. Phenyl arsenicals were likely immobilized in the sedimentthrough sulfur substitution and a subsequent sulfur bond under the prevailing sulfate reducing condition. The results of this study indicate that PAA can undergo microbiologically mediated transformation in anoxic aquifers, leading to reduced concentrations in groundwater, which indicate a (enhancend) natural attenuation potential.

Does vivianite control phosphate solubility in anoxic meadow soils?

DEFF Research Database (Denmark)

Walpersdorf, Eva Christine; Bender Koch, Christian; Heiberg, Lisa

2013-01-01

Vivianite (Fe3(PO4)2·8H2O) may precipitate in anoxic wetland soils where it may control orthophosphate (Pi) equilibrium solution concentrations at micromolar levels, and thus be of key importance in reducing excessive P from agricultural sources and eutrophication. However, vivianite equilibria...... and kinetics under in situ conditions are not fully understood and the occurrence of vivianite in wetland soils is rarely documented. In the present investigation we have monitored the temporal (November to June) variation in the pore water chemistry of a wet meadow soil (Sapric Medihemist) including...... restored. Even after 120 days following perturbation the supersaturation was still high (SIviv~6). It seems that vivianite does contribute to Pi immobilization in anoxic soil horizons, but due to slow precipitation kinetics such soils cannot maintain Pi concentrations at levels below critical thresholds...

Microbial electricity driven anoxic ammonium removal.

Science.gov (United States)

Vilajeliu-Pons, Anna; Koch, Christin; Balaguer, Maria D; Colprim, Jesús; Harnisch, Falk; Puig, Sebastià

2018-03-01

Removal of nitrogen, mainly in form of ammonium (NH 4 + ), in wastewater treatment plants (WWTPs) is a highly energy demanding process, mainly due to aeration. It causes costs of about half a million Euros per year in an average European WWTP. Alternative, more economical technologies for the removal of nitrogen compounds from wastewater are required. This study proves the complete anoxic conversion of ammonium (NH 4 + ) to dinitrogen gas (N 2 ) in continuously operated bioelectrochemical systems at the litre-scale. The removal rate is comparable to conventional WWTPs with 35 ± 10 g N m -3 d -1 with low accumulation of NO 2 - , NO 3 - , N 2 O. In contrast to classical aerobic nitrification, the energy consumption is considerable lower (1.16 ± 0.21 kWh kg -1 N, being more than 35 times less than for the conventional wastewater treatment). Biotic and abiotic control experiments confirmed that the anoxic nitrification was an electrochemical biological process mainly performed by Nitrosomonas with hydroxylamine as the main substrate (mid-point potential, E ox  = +0.67 ± 0.08 V vs. SHE). This article proves the technical feasibility and reduction of costs for ammonium removal from wastewater, investigates the underlying mechanisms and discusses future engineering needs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Discovery of enzymes for toluene synthesis from anoxic microbial communities

DEFF Research Database (Denmark)

Beller, Harry R.; Rodrigues, Andria V.; Zargar, Kamrun

2018-01-01

Microbial toluene biosynthesis was reported in anoxic lake sediments more than three decades ago, but the enzyme catalyzing this biochemically challenging reaction has never been identified. Here we report the toluene-producing enzyme PhdB, a glycyl radical enzyme of bacterial origin that catalyzes...... phenylacetate decarboxylation, and its cognate activating enzyme PhdA, a radical S-adenosylmethionine enzyme, discovered in two distinct anoxic microbial communities that produce toluene. The unconventional process of enzyme discovery from a complex microbial community (>300,000 genes), rather than from...... a microbial isolate, involved metagenomics- and metaproteomics-enabled biochemistry, as well as in vitro confirmation of activity with recombinant enzymes. This work expands the known catalytic range of glycyl radical enzymes (only seven reaction types had been characterized previously) and aromatic...

A marine heatwave drives massive losses from the world’s largest seagrass carbon stocks

KAUST Repository

Arias-Ortiz, Ariane; Serrano, Oscar; Masqué , Pere; Lavery, P. S.; Mueller, U.; Kendrick, G. A.; Rozaimi, M.; Esteban, A.; Fourqurean, J. W.; Marbà , N.; Mateo, M. A.; Murray, K.; Rule, M. J.; Duarte, Carlos M.

2018-01-01

Seagrass ecosystems contain globally significant organic carbon (C) stocks. However, climate change and increasing frequency of extreme events threaten their preservation. Shark Bay, Western Australia, has the largest C stock reported for a seagrass

Anoxic and aerobic values for the yield coefficient of the ...

African Journals Online (AJOL)

2008-04-15

Apr 15, 2008 ... Simulations with dual values (aerobic and anoxic conditions) for heterotrophic yield (modified ... mittently aerated processes can achieve a significant nitrate ...... dynamic calibration and long-term validation for an intermittently.

Microbial ecology of deep-sea hypersaline anoxic basins

KAUST Repository

Merlino, Giuseppe

2018-05-09

Deep hypersaline anoxic basins (DHABs) are unique water bodies occurring within fractures at the bottom of the sea, where the dissolution of anciently buried evaporites created dense anoxic brines that are separated by a chemocline/pycnocline from the overlying oxygenated deep-seawater column. DHABs have been described in the Gulf of Mexico, the Mediterranean Sea, the Black Sea and the Red Sea. They are characterized by prolonged historical separation of the brines from the upper water column due to lack of mixing and by extreme conditions of salinity, anoxia, and relatively high hydrostatic pressure and temperatures. Due to these combined selection factors, unique microbial assemblages thrive in these polyextreme ecosystems. The topological localization of the different taxa in the brine-seawater transition zone coupled with the metabolic interactions and niche adaptations determine the metabolic functioning and biogeochemistry of DHABs. In particular, inherent metabolic strategies accompanied by genetic adaptations have provided insights on how prokaryotic communities can adapt to salt-saturated condition. Here, we review the current knowledge on the diversity, genomics, metabolisms and ecology of prokaryotes in DHABs.

Global niche of marine anaerobic metabolisms expanded by particle microenvironments

Science.gov (United States)

Bianchi, Daniele; Weber, Thomas S.; Kiko, Rainer; Deutsch, Curtis

2018-04-01

In ocean waters, anaerobic microbial respiration should be confined to the anoxic waters found in coastal regions and tropical oxygen minimum zones, where it is energetically favourable. However, recent molecular and geochemical evidence has pointed to a much broader distribution of denitrifying and sulfate-reducing microbes. Anaerobic metabolisms are thought to thrive in microenvironments that develop inside sinking organic aggregates, but the global distribution and geochemical significance of these microenvironments is poorly understood. Here, we develop a new size-resolved particle model to predict anaerobic respiration from aggregate properties and seawater chemistry. Constrained by observations of the size spectrum of sinking particles, the model predicts that denitrification and sulfate reduction can be sustained throughout vast, hypoxic expanses of the ocean, and could explain the trace metal enrichment observed in particles due to sulfide precipitation. Globally, the expansion of the anaerobic niche due to particle microenvironments doubles the rate of water column denitrification compared with estimates based on anoxic zones alone, and changes the sensitivity of the marine nitrogen cycle to deoxygenation in a warming climate.

Laboratory experiments on the transfer dynamics of plutonium from marine sediments to sea water and to marine organisms

International Nuclear Information System (INIS)

Mo, T.; Lowman, F.G.

1975-01-01

The leachability of 239 240 Pu from a fine contaminated calcareous sediment to aerated open sea water and to anoxic sea water was measured. The distribution coefficient for 239 240 Pu from sediment to sea water was 6.1 x 10 -5 for aerated water and 2.6 x 10 -6 for anoxic water. Experiments on the uptake of 239 240 Pu by the clams Donax denticulatus, and Lucina pectinata, were done in aquaria containing kilogram quantities of sediment from the Bravo Crater at Bikini Atoll. The concentration factor for 239 240 Pu by the soft parts of these clams was about 200. All the plutonium taken up in the soft parts was associated with the gill, mantle and siphon. No plutonium was detected in the adductor muscles or hepatopancreas. The smooth surfaces of the shells of the Donax did not show any detectable plutonium, but the rough shell surfaces of the Lucina concentrated plutonium by a factor of 1.10 x 10 4 over that in the sea water. Marine periphyton cultured on glass plates in an aquarium concentrated 239 240 Pu by a factor of about 7 x 10 3 over that in the sea water. (U.S.)

Anoxic conditions drive phosphorus limitation in humid tropical forest soil microorganisms

Science.gov (United States)

Gross, A.; Pett-Ridge, J.; Weber, P. K.; Blazewicz, S.; Silver, W. L.

2017-12-01

The elemental stoichiometry of carbon (C), nitrogen (N) and phosphorus (P) of soil microorganisms (C:N:P ratios) regulates transfers of energy and nutrients to higher trophic levels. In humid tropical forests that grow on P-depleted soils, the ability of microbes to concentrate P from their surroundings likely plays a critical role in P-retention and ultimately in forest productivity. Models predict that climate change will cause dramatic changes in rainfall patterns in the humid tropics and field studies have shown these changes can affect the redox state of tropical forest soils, influencing soil respiration and biogeochemical cycling. However, the responses of soil microorganisms to changing environmental conditions are not well known. Here, we incubated humid tropical soils under oxic or anoxic conditions with substrates differing in both C:P stoichiometry and lability, to assess how soil microorganisms respond to different redox regimes. We found that under oxic conditions, microbial C:P ratios were similar to the global optimal ratio (55:1), indicating most microbial cells can adapt to persistent aerated conditions in these soils. However, under anoxic conditions, the ability of soil microbes to acquire soil P declined and their C:P ratios shifted away from the optimal ratio. NanoSIMS elemental imaging of single cells extracted from soil revealed that under anoxic conditions, C:P ratios were above the microbial optimal value in 83% of the cells, in comparison to 41% under oxic conditions. These data suggest microbial growth efficiency switched from being energy limited under oxic conditions to P-limited under anoxic conditions, indicating that, microbial growth in low P humid tropical forests soils may be most constrained by P-limitation when conditions are oxygen-limited. We suggest that differential microbial responses to soil redox states could have important implications for productivity of humid tropical forests under future climate scenarios.

Anoxic conditions are beneficial for abiotic diclofenac removal from water with manganese oxide (MnO2)

NARCIS (Netherlands)

Liu, Wenbo; Sutton, Nora B.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

2018-01-01

This is the first study examining pharmaceutical removal under anoxic conditions with MnO2. This study compares the abiotic removal of seven pharmaceuticals with reactive MnO2 particles in the presence of oxygen (oxic conditions) and in the absence of oxygen (anoxic conditions). Due to the novelty

Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets

Science.gov (United States)

Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

2011-01-01

Abstract We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases—and therefore the life that produces them—if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. Key Words: Exoplanets—Biosignatures—Anoxic atmospheres—Planetary atmospheres—Remote life detection—Photochemistry. Astrobiology 11, 419–441. PMID:21663401

Pressure adaptation is linked to thermal adaptation in salt-saturated marine habitats.

Science.gov (United States)

Alcaide, María; Stogios, Peter J; Lafraya, Álvaro; Tchigvintsev, Anatoli; Flick, Robert; Bargiela, Rafael; Chernikova, Tatyana N; Reva, Oleg N; Hai, Tran; Leggewie, Christian C; Katzke, Nadine; La Cono, Violetta; Matesanz, Ruth; Jebbar, Mohamed; Jaeger, Karl-Erich; Yakimov, Michail M; Yakunin, Alexander F; Golyshin, Peter N; Golyshina, Olga V; Savchenko, Alexei; Ferrer, Manuel

2015-02-01

The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5°C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65°C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16°C, was shown to contain halopiezophilic-like enzymes that are most active at 70°C and with denaturing temperatures of 71.4°C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Sedimentary Mercury Enrichments as a Marker for Submarine Large Igneous Province Volcanism? Evidence From the Mid-Cenomanian Event and Oceanic Anoxic Event 2 (Late Cretaceous)

Science.gov (United States)

Scaife, J. D.; Ruhl, M.; Dickson, A. J.; Mather, T. A.; Jenkyns, H. C.; Percival, L. M. E.; Hesselbo, S. P.; Cartwright, J.; Eldrett, J. S.; Bergman, S. C.; Minisini, D.

2017-12-01

Oceanic Anoxic Event 2 (OAE 2), during the Cenomanian-Turonian transition (˜94 Ma), was the largest perturbation of the global carbon cycle in the mid-Cretaceous and can be recognized by a positive carbon-isotope excursion in sedimentary strata. Although OAE 2 has been linked to large-scale volcanism, several large igneous provinces (LIPs) were active at this time (e.g., Caribbean, High Arctic, Madagascan, Ontong-Java) and little clear evidence links OAE 2 to a specific LIP. The Mid-Cenomanian Event (MCE, ˜96 Ma), identified by a small, 1‰ positive carbon-isotope excursion, is often referred to as a prelude to OAE 2. However, no underlying cause has yet been demonstrated and its relationship to OAE 2 is poorly constrained. Here we report sedimentary mercury (Hg) concentration data from four sites, three from the southern margin of the Western Interior Seaway and one from Demerara Rise, in the equatorial proto-North Atlantic Ocean. We find that, in both areas, increases in mercury concentrations and Hg/TOC ratios coincide with the MCE and the OAE 2. However, the increases found in these sites are of a lower magnitude than those found in records of many other Mesozoic events, possibly characteristic of a marine rather than atmospheric dispersal of mercury for both events. Combined, the new mercury data presented here are consistent with an initial magmatic pulse at the time of the MCE, with a second, greater pulse at the onset of OAE 2, possibly related to the emplacement of LIPs in the Pacific Ocean and/or the High Arctic.

Effects of soil erosion and anoxic–euxinic ocean in the Permian–Triassic marine crisis

Directory of Open Access Journals (Sweden)

Kunio Kaiho

2016-08-01

Full Text Available The largest mass extinction of biota in the Earth’s history occurred during the Permian–Triassic transition and included two extinctions, one each at the latest Permian (first phase and earliest Triassic (second phase. High seawater temperature in the surface water accompanied by euxinic deep-intermediate water, intrusion of the euxinic water to the surface water, a decrease in pH, and hypercapnia have been proposed as direct causes of the marine crisis. For the first-phase extinction, we here add a causal mechanism beginning from massive soil and rock erosion and leading to algal blooms, release of toxic components, asphyxiation, and oxygen-depleted nearshore bottom water that created environmental stress for nearshore marine animals. For the second-phase extinction, we show that a soil and rock erosion/algal bloom event did not occur, but culmination of anoxia–euxinia in intermediate waters did occur, spanning the second-phase extinction. We investigated sedimentary organic molecules, and the results indicated a peak of a massive soil erosion proxy followed by peaks of marine productivity proxy. Anoxic proxies of surface sediments and water occurred in the shallow nearshore sea at the eastern and western margins of the Paleotethys at the first-phase extinction horizon, but not at the second-phase extinction horizon. Our reconstruction of ocean redox structure at low latitudes indicates that a gradual increase in temperature spanning the two extinctions could have induced a gradual change from a well-mixed oxic to a stratified euxinic ocean beginning immediately prior to the first-phase extinction, followed by culmination of anoxia in nearshore surface waters and of anoxia and euxinia in the shallow-intermediate waters at the second-phase extinction over a period of approximately one million years or more. Enhanced global warming, ocean acidification, and hypercapnia could have caused the second-phase extinction approximately 60 kyr after

The relationship between the anoxic sensitivity and the extent of sensitization by nitrous oxide

International Nuclear Information System (INIS)

Ewing, D.; Walton, H.L.; Guilfoil, D.S.; Ohm, M.B.

1991-01-01

Nitrous oxide reacts during irradiation to increase the yield of ·OH, a radical many believe to be a major cause of lethality. Logically, one would expect N 2 O to be a radiation sensitizer. In some instances it is, while in others it is not. In some cases we can explain why N 2 O fails to sensitize; factors such as dose rate, cell concentration, buffer composition and ionic strength all influence when N 2 O will sensitize and if it sensitizes, by what magnitude. Based on the results presented here with multiple strains of procaryotic and eucaryotic cells, we believe the anoxic sensitivity is another critical factor that governs whether N 2 O will sensitize. Our data, with data from the literature, show a relationship between the anoxic sensitivity and the N 2 O enhancement ratio. N 2 O does not sensitize in vitro unless the anoxic sensitivity (inactivation constant, K) is less than ∼ 0.2 daGy -1 . (author)

Alternating anoxic feast/aerobic famine condition for improving granular sludge formation in sequencing batch airlift reactor at reduced aeration rate.

Science.gov (United States)

Wan, Junfeng; Bessière, Yolaine; Spérandio, Mathieu

2009-12-01

In this study the influence of a pre-anoxic feast period on granular sludge formation in a sequencing batch airlift reactor is evaluated. Whereas a purely aerobic SBR was operated as a reference (reactor R2), another reactor (R1) was run with a reduced aeration rate and an alternating anoxic-aerobic cycle reinforced by nitrate feeding. The presence of pre-anoxic phase clearly improved the densification of aggregates and allowed granular sludge formation at reduced air flow rate (superficial air velocity (SAV)=0.63cms(-1)). A low sludge volume index (SVI(30)=45mLg(-1)) and a high MLSS concentration (9-10gL(-1)) were obtained in the anoxic/aerobic system compared to more conventional results for the aerobic reactor. A granular sludge was observed in the anoxic/aerobic system whilst only flocs were observed in the aerobic reference even when operated at a high aeration rate (SAV=2.83cms(-1)). Nitrification was maintained efficiently in the anoxic/aerobic system even when organic loading rate (OLR) was increased up to 2.8kgCODm(-3)d(-1). In the contrary nitrification was unstable in the aerobic system and dropped at high OLR due to competition between autotrophic and heterotrophic growth. The presence of a pre-anoxic period positively affected granulation process via different mechanisms: enhancing heterotrophic growth/storage deeper in the internal anoxic layer of granule, reducing the competition between autotrophic and heterotrophic growth. These processes help to develop dense granular sludge at a moderate aeration rate. This tends to confirm that oxygen transfer is the most limiting factor for granulation at reduced aeration. Hence the use of an alternative electron acceptor (nitrate or nitrite) should be encouraged during feast period for reducing energy demand of the granular sludge process.

Timing of the Toarcian Ocean Anoxic Event (Early Jurassic) from correlation of astronomically forced global stratigraphic sections

Science.gov (United States)

Huang, C.; Hinnov, L. A.; Hesselbo, S. P.

2012-12-01

The Early Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic Period is associated with a major negative carbon isotope excursion (CIE), mass extinction, marine transgression and global warming. The Toarcian OAE is thought to have been caused by flood basalt magmatism, and may have been a trigger for mass extinction. However, these proposed causes of the Toarcian OAE and associated biotic crisis are not adequately resolved by a precise chronology. The duration of the Toarcian OAE has been estimated to be anywhere from ~0.12 to ~0.9 Myr, most recently 0.74 to 3.26 Myr from U-Pb dating. The CIE associated with the Toarcian OAE has a similar pattern at numerous localities, and there is evidence for astronomical forcing of marine carbon isotopes. Here we estimate a duration of ~625 kyr for the main negative CIE, ~860 kyr for the polymorphum zone and >1.58 Myr for the levisoni zone based on 405-kyr astronomical eccentricity tuning of the marine section at Peniche (Portugal). This 405-kyr tuned series provides a ~2.5 Myr continuous high-resolution chronology through the Early Toarcian. There are 6, or possibly 7 short eccentricity cycles in the main CIE interval at Peniche. To confirm this astronomically based estimate, we analyzed five other sections at Yorkshire (UK), Dotternhausen (Germany), Valdorbia (Italy), Mechowo (Poland) and Serrucho, Neuquén (Argentina), from marine and terrestrial carbon isotopic series. These six stratigraphic sections from Early Jurassic western Tethys and eastern Panthalassa record the Toarcian OAE with ~6 prominent carbon isotope cycles in the CIE that provide us a 600 ± 100 kyr duration. The Peniche 405 kyr-tuned series indicates that the pre- and post-CIE intervals experienced strong precession-eccentricity-forced climate change, whereas the CIE interval is marked by dominant obliquity forcing. These dramatic and abrupt changes in astronomical response in the carbon isotopes point to fundamental shifting in the Early Toarcian

Research and Application of Marine Microbial Enzymes: Status and Prospects

Science.gov (United States)

Zhang, Chen; Kim, Se-Kwon

2010-01-01

Over billions of years, the ocean has been regarded as the origin of life on Earth. The ocean includes the largest range of habitats, hosting the most life-forms. Competition amongst microorganisms for space and nutrients in the marine environment is a powerful selective force, which has led to evolution. The evolution prompted the marine microorganisms to generate multifarious enzyme systems to adapt to the complicated marine environments. Therefore, marine microbial enzymes can offer novel biocatalysts with extraordinary properties. This review deals with the research and development work investigating the occurrence and bioprocessing of marine microbial enzymes. PMID:20631875

Anaerobic degradation of cyclohexane by sulfate-reducing bacteria from hydrocarbon-contaminated marine sediments

Directory of Open Access Journals (Sweden)

Ulrike eJaekel

2015-02-01

Full Text Available The fate of cyclohexane, often used as a model compound for the biodegradation of cyclic alkanes due to its abundance in crude oils, in anoxic marine sediments has been poorly investigated. In the present study, we obtained an enrichment culture of cyclohexane-degrading sulfate-reducing bacteria from hydrocarbon-contaminated intertidal marine sediments. Microscopic analyses showed an apparent dominance by oval cells of 1.5×0.8 m. Analysis of a 16S rRNA gene library, followed by whole-cell hybridization with group- and sequence-specific oligonucleotide probes showed that these cells belonged to a single phylotype, and were accounting for more than 80% of the total cell number. The dominant phylotype, affiliated with the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria, is proposed to be responsible for the degradation of cyclohexane. Quantitative growth experiments showed that cyclohexane degradation was coupled with the stoichiometric reduction of sulfate to sulfide. Substrate response tests corroborated with hybridization with a sequence-specific oligonucleotide probe suggested that the dominant phylotype apparently was able to degrade other cyclic and n-alkanes, including the gaseous alkanes propane and n-butane. Based on GC-MS analyses of culture extracts cyclohexylsuccinate was identified as a metabolite, indicating an activation of cyclohexane by addition to fumarate. Other metabolites detected were 3-cyclohexylpropionate and cyclohexanecarboxylate providing evidence that the overall degradation pathway of cyclohexane under anoxic conditions is analogous to that of n-alkanes.

Assessing global carbon burial during Oceanic Anoxic Event 2, Cenomanian-Turonian boundary event

Science.gov (United States)

Owens, J. D.; Lyons, T. W.; Lowery, C. M.

2017-12-01

Reconstructing the areal extent and total amount of organic carbon burial during ancient events remains elusive even for the best documented oceanic anoxic event (OAE) in Earth history, the Cenomanian-Turonian boundary event ( 93.9 Ma), or OAE 2. Reports from 150 OAE 2 localities provide a wide global distribution. However, despite the large number of sections, the majority are found within the proto-Atlantic and Tethyan oceans and interior seaways. Considering these gaps in spatial coverage, the pervasive increase in organic carbon (OC) burial during OAE2 that drove carbon isotope values more positive (average of 4‰) can provide additional insight. These isotope data allow us to estimate the total global burial of OC, even for unstudied portions of the global ocean. Thus, we can solve for any `missing' OC sinks by comparing our estimates from a forward carbon-isotope box model with the known, mapped distribution of OC for OAE 2 sediments. Using the known OC distribution and reasonably extrapolating to the surrounding regions of analogous depositional conditions accounts for only 13% of the total seafloor, mostly in marginal marine settings. This small geographic area accounts for more OC burial than the entire modern ocean, but significantly less than the amount necessary to produce the observed isotope record. Using modern and OAE 2 average OC rates we extrapolate further to appropriate depositional settings in the unknown portions of seafloor, mostly deep abyssal plains. This addition significantly increases the predicted amount buried but still does not account for total burial. Additional sources, including hydrocarbon migration, lacustrine, and coal also cannot account for the missing OC. This difference points to unknown portions of the open ocean with high TOC contents or exceptionally high TOC in productive marginal marine regions, which are underestimated in our extrapolations. This difference might be explained by highly productive margins within the

ENVIRONMENTAL CHARACTERISTICS AFFECTING REDUCTIVE TRANSFORMATION OF ORGANIC POLLUTANTS IN ANOXIC SEDIMENTS

Science.gov (United States)

Reductive transformations are important processes for determining the fate of organic pollutants in anoxic environments. These processes are most often microbially mediated by both direct and indirect means. For example, specific bacteria transform organic pollutants directly as ...

Protist communities in a marine oxygen minimum zone off Costa Rica by 454 pyrosequencing

Science.gov (United States)

Jing, H.; Rocke, E.; Kong, L.; Xia, X.; Liu, H.; Landry, M. R.

2015-08-01

Marine planktonic protists, including microalgae and protistan grazers, are an important contributor to global primary production and carbon and mineral cycles, however, little is known about their population shifts along the oxic-anoxic gradient in the water column. We used 454 pyrosequencing of the 18S rRNA gene and gene transcripts to study the community composition of whole and active protists throughout a water column in the Costa Rica Dome, where a stable oxygen minimum zone (OMZ) exists at a depth of 400~700 m. A clear shift of protist composition from photosynthetic Dinoflagellates in the surface to potential parasitic Dinoflagellates and Ciliates in the deeper water was revealed along the vertical profile at both rRNA and rDNA levels. Those protist groups recovered only at the rDNA level represent either lysed aggregates sinking from the upper waters or potential hosts for parasitic groups. UPGMA clustering demonstrated that total and active protists in the anoxic core of OMZ (550 m) were distinct from those in other water depths. The reduced community diversity and presence of a parasitic/symbiotic trophic lifestyle in the OMZ, especially the anoxic core, suggests that OMZs can exert a selective pressure on protist communities. Such changes in community structure and a shift in trophic lifestyle could result in a modulation of the microbial loop and associated biogeochemical cycling.

Incineration of tannery sludge under oxic and anoxic conditions: study of chromium speciation.

Science.gov (United States)

Kavouras, P; Pantazopoulou, E; Varitis, S; Vourlias, G; Chrissafis, K; Dimitrakopulos, G P; Mitrakas, M; Zouboulis, A I; Karakostas, Th; Xenidis, A

2015-01-01

A tannery sludge, produced from physico-chemical treatment of tannery wastewaters, was incinerated without any pre-treatment process under oxic and anoxic conditions, by controlling the abundance of oxygen. Incineration in oxic conditions was performed at the temperature range from 300°C to 1200°C for duration of 2h, while in anoxic conditions at the temperature range from 400°C to 600°C and varying durations. Incineration under oxic conditions at 500°C resulted in almost total oxidation of Cr(III) to Cr(VI), with CaCrO4 to be the crystalline phase containing Cr(VI). At higher temperatures a part of Cr(VI) was reduced, mainly due to the formation of MgCr2O4. At 1200°C approximately 30% of Cr(VI) was reduced to Cr(III). Incineration under anoxic conditions substantially reduced the extent of oxidation of Cr(III) to Cr(VI). Increase of temperature and duration of incineration lead to increase of Cr(VI) content, while no chromium containing crystalline phase was detected. Copyright © 2014 Elsevier B.V. All rights reserved.

Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots

NARCIS (Netherlands)

Peuke, A.D.; Gessler, A.; Trumbore, S.; Windt, C.W.; Homan, N.; Gerkema, E.; As, van H.

2015-01-01

Anoxic conditions should hamper the transport of sugar in the phloem, as this is an active process. The canopy is a carbohydrate source and the roots are carbohydrate sinks.By fumigating the shoot with N2 or flooding the rhizosphere, anoxic conditions in the source or sink, respectively, were

Succession of Bacterial Communities in a Seasonally Stratified Lake with an Anoxic and Sulfidic Hypolimnion

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Muhe Diao

2017-12-01

Full Text Available Although bacteria play key roles in aquatic food webs and biogeochemical cycles, information on the seasonal succession of bacterial communities in lakes is still far from complete. Here, we report results of an integrative study on the successional trajectories of bacterial communities in a seasonally stratified lake with an anoxic hypolimnion. The bacterial community composition of epilimnion, metalimnion, and hypolimnion diverged during summer stratification and converged when the lake was mixed. In contrast, bacterial communities in the sediment remained relatively stable over the year. Phototrophic Cyanobacteria and heterotrophic Actinobacteria, Alphaproteobacteria and Planktomycetes were abundant in the aerobic epilimnion, Gammaproteobacteria (mainly Chromatiaceae dominated in the metalimnion, and Chlorobi, Betaproteobacteria, Deltaproteobacteria, and Firmicutes were abundant in the anoxic sulfidic hypolimnion. Anoxic but nonsulfidic conditions expanded to the surface layer during fall turnover, when the epilimnion, metalimnion and upper hypolimnion mixed. During this period, phototrophic sulfur bacteria (Chromatiaceae and Chlorobi disappeared, Polynucleobacter (Betaproteobacteria and Methylobacter (Gammaproteobacteria spread out from the former meta- and hypolimnion to the surface layer, and Epsilonproteobacteria dominated in the bottom water layer. Cyanobacteria and Planktomycetes regained dominance in early spring, after the oxygen concentration was restored by winter mixing. In total, these results show large spatio-temporal changes in bacterial community composition, especially during transitions from oxic to anoxic and from sulfidic to nonsulfidic conditions.

Plutonium behavior during the early diagenesis of marine sediments: applications to two marine environments labelled by radionuclides released from reprocessing plants

International Nuclear Information System (INIS)

Gouzy, A.

2004-12-01

The plutonium released into the English Channel and the Irish Sea by nuclear fuel reprocessing plants is mainly associated to sediments. Nevertheless, this association is partially reversible. This work combines a field study, carried out on the Cumbrian mud patch and the Esk estuary (Eastern Irish Sea), and laboratory experiments performed on carbonaceous coarse-grained sediments collected in the Central Channel. It presents new data on the plutonium solid partition in sediments and suggests realistic scenarios for describing its release from sediments to the water column. The role of reactive sulphides acting as temporary sink phases is shown in anoxic sediments; those sulphides are liable to release dissolved plutonium upon their oxidation. The plutonium is also bound to carbonates within the carbonaceous matrix and as carbonate surface complexes. Conceptual schemes of the behaviour of the plutonium in marine sediments are proposed; they highlight the strong remobilization potential of plutonium from marine sediments to the interstitial water. Its plutonium content can be injected into the overlying water column. (author)

The relationship between the anoxic sensitivity and the extent of sensitization by nitrous oxide

Energy Technology Data Exchange (ETDEWEB)

Ewing, D.; Walton, H.L.; Guilfoil, D.S.; Ohm, M.B. (Hahnemann Univ., Philadelphia, PA (USA). Dept. of Radiation Oncology and Nuclear Medicine)

1991-03-01

Nitrous oxide reacts during irradiation to increase the yield of center dotOH, a radical many believe to be a major cause of lethality. Logically, one would expect N{sub 2}O to be a radiation sensitizer. In some instances it is, while in others it is not. In some cases we can explain why N{sub 2}O fails to sensitize; factors such as dose rate, cell concentration, buffer composition and ionic strength all influence when N{sub 2}O will sensitize and if it sensitizes, by what magnitude. Based on the results presented here with multiple strains of procaryotic and eucaryotic cells, we believe the anoxic sensitivity is another critical factor that governs whether N{sub 2}O will sensitize. Our data, with data from the literature, show a relationship between the anoxic sensitivity and the N{sub 2}O enhancement ratio. N{sub 2}O does not sensitize in vitro unless the anoxic sensitivity (inactivation constant, K) is less than {similar to} 0.2 daGy{sup -1}. (author).

Impacts of extreme weather events on highly eutrophic marine ecosystem (Rogoznica Lake, Adriatic coast)

Science.gov (United States)

Ciglenečki, I.; Janeković, I.; Marguš, M.; Bura-Nakić, E.; Carić, M.; Ljubešić, Z.; Batistić, M.; Hrustić, E.; Dupčić, I.; Garić, R.

2015-10-01

Rogoznica Lake is highly eutrophic marine system located on the Eastern Adriatic coast (43°32‧N, 15°58‧E). Because of the relatively small size (10,276 m2) and depth (15 m) it experiences strong natural and indirect anthropogenic influences. Dynamics within the lake is characterized by the extreme and highly variable environmental conditions (seasonal variations in salinity and temperature, water stratification and mixing, redox and euxinic conditions, concentrations of nutrients) which significantly influence the biology inside the lake. Due to the high phytoplankton activity, the upper part of the water column is well oxygenated, while hypoxia/anoxia usually occurs in the bottom layers. Anoxic part of the water column is characterized with high concentrations of sulfide (up to 5 mM) and nutrients (NH4+ up to 315 μM; PO43- up to 53 μM; SiO44- up to 680 μM) indicating the pronounced remineralization of the allochthonous organic matter, produced in the surface waters. The mixolimnion varies significantly within a season feeling effects of the Adriatic atmospheric and ocean dynamics (temperature, wind, heat fluxes, rainfall) which all affect the vertical stability and possibly induce vertical mixing and/or turnover. Seasonal vertical mixing usually occurs during the autumn/winter upon the breakdown of the stratification, injecting oxygen-rich water from the surface into the deeper layers. Depending on the intensity and duration of the vertical dynamics (slower diffusion and/or faster turnover of the water layers) anoxic conditions could developed within the whole water column. Extreme weather events such as abrupt change in the air temperature accompanied with a strong wind and consequently heat flux are found to be a key triggering mechanism for the fast turnover, introducing a large amount of nutrients and sulfur species from deeper parts to the surface. Increased concentration of nutrients, especially ammonium, phosphate, and silicates persisting for

Benthic protists and fungi of Mediterranean deep hypsersaline anoxic basin redoxcline sediments.

Science.gov (United States)

Bernhard, Joan M; Kormas, Konstantinos; Pachiadaki, Maria G; Rocke, Emma; Beaudoin, David J; Morrison, Colin; Visscher, Pieter T; Cobban, Alec; Starczak, Victoria R; Edgcomb, Virginia P

2014-01-01

Some of the most extreme marine habitats known are the Mediterranean deep hypersaline anoxic basins (DHABs; water depth ∼3500 m). Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB water-column haloclines and brines, the existence and activity of benthic DHAB protists have rarely been explored. Here, we report findings regarding protists and fungi recovered from sediments of three DHAB (Discovery, Urania, L' Atalante) haloclines, and compare these to communities from sediments underlying normoxic waters of typical Mediterranean salinity. Halocline sediments, where the redoxcline impinges the seafloor, were studied from all three DHABs. Microscopic cell counts suggested that halocline sediments supported denser protist populations than those in adjacent control sediments. Pyrosequencing analysis based on ribosomal RNA detected eukaryotic ribotypes in the halocline sediments from each of the three DHABs, most of which were fungi. Sequences affiliated with Ustilaginomycotina Basidiomycota were the most abundant eukaryotic signatures detected. Benthic communities in these DHABs appeared to differ, as expected, due to differing brine chemistries. Microscopy indicated that only a low proportion of protists appeared to bear associated putative symbionts. In a considerable number of cases, when prokaryotes were associated with a protist, DAPI staining did not reveal presence of any nuclei, suggesting that at least some protists were carcasses inhabited by prokaryotic scavengers.

Tracing Carbon Cycling in the Atmosphere and Oceans During the Cretaceous Ocean Anoxic Event 2 (OAE2, 94Ma)

Science.gov (United States)

Moran, S. A. M.; Boudinot, F. G.; Dildar, N.; Sepúlveda, J.

2017-12-01

We present a high-resolution record of compound-specific stable carbon isotope data from short-chain—aquatic algae—and long-chain n-alkanes—terrestrial plants—preserved in sedimentary sequences from the Smokey Hollow #1 (SH1) core in the Grand Staircase Escalante National Monument in southern Utah. The study area covered by SH1 core was situated at the western margin of the Western Interior Seaway during the Cretaceous Ocean Anoxic Event (OAE2, 94Ma.), and was characterized by high sedimentation rates and enhanced preservation of both marine and terrestrial organic matter. Short- and long-chain n-alkanes were isolated and purified from branched and cyclic aliphatic hydrocarbons using an optimized urea adduction protocol, and δ13Cn-alkane was measured using a Thermo MAT253 GC-C-IR-MS. We use the δ13Cn-alkane from aquatic and terrestrial sources to better understand carbon cycle interactions in the oceanic and atmospheric carbon pools across this event. Our results indicate that the δ13C of terrestrial plants experienced a faster and more pronounced positive carbon isotope excursion compared to marine sources. We will discuss how these results can inform models of carbon cycle interactions between the ocean and the atmosphere during greenhouse climates, and how they can be used to trace possible sources of CO2.

Vertical distributions and speciation of dissolved rare earth elements in the anoxic brines of Bannock Basin, eastern Mediterranean Sea

NARCIS (Netherlands)

Schijf, Johan; Baar, Hein J.W. de; Millero, Frank J.; Byrne, R.H.

1995-01-01

Vertical distributions of dissolved rare earth elements (REEs) are presented for the anoxic, highly sulfidic brines of Bannock Basin in the eastern Mediterranean Sea. REE concentrations at the seawater-brine interface are the highest ever recorded in the water column of an anoxic basin and

Biotransformation potential of phytosterols under anoxic and anaerobic conditions.

Science.gov (United States)

Dykstra, C M; Giles, H D; Banerjee, S; Pavlostathis, S G

2014-01-01

The biotransformation potential of three phytosterols (campesterol, stigmasterol and β-sitosterol) under denitrifying, sulfate-reducing and fermentative/methanogenic conditions was assessed. Using a group contribution method, the standard Gibbs free energy of phytosterols was calculated and used to perform theoretical energetic calculations. The oxidation of phytosterols under aerobic, nitrate-reducing, sulfate-reducing and methanogenic conditions was determined to be energetically feasible. However, using semi-continuously fed cultures maintained at 20-22 °C over 16 weekly feeding cycles (112 days; retention time, 21 days), phytosterol removal was observed under nitrate-reducing and sulfate-reducing conditions, but not under fermentative/methanogenic conditions. Under sulfate-reducing conditions, stigmast-4-en-3-one was identified as an intermediate of phytosterol biotransformation, a reaction more likely carried out by dehydrogenases/isomerases, previously reported to act on cholesterol under both oxic and anoxic (denitrifying) conditions. Further study of the biotransformation of phytosterols under anoxic/anaerobic conditions is necessary to delineate the factors and conditions leading to enhanced phytosterol biodegradation and the development of effective biological treatment systems for the removal of phytosterols from pulp and paper wastewaters and other phytosterol-bearing waste streams.

A Case of Anoxic Brain Injury Presenting with Agraphia of kanji in the Foreground

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Yasutaka Kobayashi

2017-03-01

Full Text Available A 63-year-old woman was hospitalized for rehabilitation from the aftereffects of an anoxic brain injury. In addition to a general cognitive decline, agraphia of kana and kanji was noted at the time of admission, which had advanced to agraphia which is dominant in kanji at the time of hospital discharge. Brain magnetic resonance imaging revealed no stroke lesions, and brain perfusion scintigraphy found a decreased blood flow in the bilateral parietal lobes. We hereby report on this case because case reports on agraphia caused by anoxic brain injury are extremely rare.

Effective removal of bromate in nitrate-reducing anoxic zones during managed aquifer recharge for drinking water treatment: Laboratory-scale simulations.

Science.gov (United States)

Wang, Feifei; van Halem, Doris; Ding, Lei; Bai, Ying; Lekkerkerker-Teunissen, Karin; van der Hoek, Jan Peter

2018-03-01

The removal of bromate (BrO 3 - ) as a by-product of ozonation in subsequent managed aquifer recharge (MAR) systems, specifically in anoxic nitrate (NO 3 - )-reducing zones, has so far gained little attention. In this study, batch reactors and columns were used to explore the influence of NO 3 - and increased assimilable organic carbon (AOC) due to ozonation pre-treatment on BrO 3 - removal in MAR systems. 8 m column experiments were carried out for 10 months to investigate BrO 3 - behavior in anoxic NO 3 - -reducing zones of MAR systems. Anoxic batch experiments showed that an increase of AOC promoted microbial activity and corresponding BrO 3 - removal. A drastic increase of BrO 3 - biodegradation was observed in the sudden absence of NO 3 - in both batch reactors and columns, indicating that BrO 3 - and NO 3 - competed for biodegradation by denitrifying bacteria and NO 3 - was preferred as an electron acceptor under the simultaneous presence of NO 3 - and BrO 3 - . However, within 75 days' absence of NO 3 - in the anoxic column, BrO 3 - removal gradually decreased, indicating that the presence of NO 3 - is a precondition for denitrifying bacteria to reduce BrO 3 - in NO 3 - -reducing anoxic zones. In the 8 m anoxic column set-up (retention time 6 days), the BrO 3 - removal achieved levels as low as 1.3 μg/L, starting at 60 μg/L (98% removal). Taken together, BrO 3 - removal is likely to occur in vicinity of NO 3 - -reducing anoxic zones, so MAR systems following ozonation are potentially effective to remove BrO 3 - . Copyright © 2017. Published by Elsevier Ltd.

Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying polyphosphate-accumulating organisms.

Science.gov (United States)

Kishida, Naohiro; Kim, Juhyun; Tsuneda, Satoshi; Sudo, Ryuichi

2006-07-01

In a biological nutrient removal (BNR) process, the utilization of denitrifying polyphosphate-accumulating organisms (DNPAOs) has many advantages such as effective use of organic carbon substrates and low sludge production. As a suitable process for the utilization of DNPAOs in BNR, an anaerobic/oxic/anoxic granular sludge (AOAGS) process was proposed in this study. In spite of performing aeration for nitrifying bacteria, the AOAGS process can create anaerobic/anoxic conditions suitable for the cultivation of DNPAOs because anoxic zones exist inside the granular sludge in the oxic phase. Thus, DNPAOs can coexist with nitrifying bacteria in a single reactor. In addition, the usability of DNPAOs in the reactor can be improved by adding the anoxic phase after the oxic phase. These characteristics enable the AOAGS process to attain effective removal of both nitrogen and phosphorus. When acetate-based synthetic wastewater (COD: 600 mg/L, NH4-N: 60 mg/L, PO(4)-P: 10 mg/L) was supplied to a laboratory-scale sequencing batch reactor under the operation of anaerobic/oxic/anoxic cycles, granular sludge with a diameter of 500 microm was successfully formed within 1 month. Although the removal of both nitrogen and phosphorus was almost complete at the end of the oxic phase, a short anoxic period subsequent to the oxic phase was necessary for further removal of nitrogen and phosphorus. As a result, effluent concentrations of NH(4)-N, NO(x)-N and PO(4)-P were always lower than 1 mg/L. It was found that penetration depth of oxygen inside the granular sludge was approximately 100 microm by microsensor measurements. In addition, from the microbiological analysis by fluorescence in situ hybridization, existence depth of polyphosphate-accumulating organisms was further than the maximum oxygen penetration depth. The water quality data, oxygen profiles and microbial community structure demonstrated that DNPAOs inside the granular sludge may be responsible for denitrification in the

The largest Silurian vertebrate and its palaeoecological implications

Science.gov (United States)

Choo, Brian; Zhu, Min; Zhao, Wenjin; Jia, Liaotao; Zhu, You'an

2014-01-01

An apparent absence of Silurian fishes more than half-a-metre in length has been viewed as evidence that gnathostomes were restricted in size and diversity prior to the Devonian. Here we describe the largest pre-Devonian vertebrate (Megamastax amblyodus gen. et sp. nov.), a predatory marine osteichthyan from the Silurian Kuanti Formation (late Ludlow, ~423 million years ago) of Yunnan, China, with an estimated length of about 1 meter. The unusual dentition of the new form suggests a durophagous diet which, combined with its large size, indicates a considerable degree of trophic specialisation among early osteichthyans. The lack of large Silurian vertebrates has recently been used as constraint in palaeoatmospheric modelling, with purported lower oxygen levels imposing a physiological size limit. Regardless of the exact causal relationship between oxygen availability and evolutionary success, this finding refutes the assumption that pre-Emsian vertebrates were restricted to small body sizes. PMID:24921626

Biodiversity's big wet secret: the global distribution of marine biological records reveals chronic under-exploration of the deep pelagic ocean.

Directory of Open Access Journals (Sweden)

Thomas J Webb

Full Text Available BACKGROUND: Understanding the distribution of marine biodiversity is a crucial first step towards the effective and sustainable management of marine ecosystems. Recent efforts to collate location records from marine surveys enable us to assemble a global picture of recorded marine biodiversity. They also effectively highlight gaps in our knowledge of particular marine regions. In particular, the deep pelagic ocean--the largest biome on Earth--is chronically under-represented in global databases of marine biodiversity. METHODOLOGY/PRINCIPAL FINDINGS: We use data from the Ocean Biogeographic Information System to plot the position in the water column of ca 7 million records of marine species occurrences. Records from relatively shallow waters dominate this global picture of recorded marine biodiversity. In addition, standardising the number of records from regions of the ocean differing in depth reveals that regardless of ocean depth, most records come either from surface waters or the sea bed. Midwater biodiversity is drastically under-represented. CONCLUSIONS/SIGNIFICANCE: The deep pelagic ocean is the largest habitat by volume on Earth, yet it remains biodiversity's big wet secret, as it is hugely under-represented in global databases of marine biological records. Given both its value in the provision of a range of ecosystem services, and its vulnerability to threats including overfishing and climate change, there is a pressing need to increase our knowledge of Earth's largest ecosystem.

A comparative study of phosphate sorption in lowland soils under oxic and anoxic conditions

DEFF Research Database (Denmark)

Heiberg, Lisa; Pedersen, Thomas Vils; Jensen, Henning S.

2010-01-01

of 36 to 93% of the dithionite-extractable FeIII (FeBD). Langmuir fitted Pi sorption isotherms showed a Pi release of up to 1.1 mmol kg-1 in six soils when Pi concentrations in the matrix (Psol) were lower than 10 µM. Phosphate desorption was attributed to dissolution of amorphous iron oxides......, and higher pH under anoxic conditions. The point of zero net sorption (EPC0) increased 2- to 10-fold on reduction. Five soils showed higher Pi sorption capacities in the anoxic than in the oxic state at higher Psol concentrations. Solubility calculations indicated that precipitation of vivianite or similar...

Anoxic degradation of nitrogenous heterocyclic compounds by activated sludge and their active sites.

Science.gov (United States)

Xu, Peng; Han, Hongjun; Zhuang, Haifeng; Hou, Baolin; Jia, Shengyong; Wang, Dexin; Li, Kun; Zhao, Qian

2015-05-01

The potential for degradation of five nitrogenous heterocyclic compounds (NHCs), i.e., imidazole, pyridine, indole, quinoline, and carbazole, was investigated under anoxic conditions with acclimated activated sludge. Results showed that NHCs with initial concentration of 50 mg/L could be completely degraded within 60 hr. The degradation of five NHCs was dependent upon the chemical structures with the following sequence: imidazole>pyridine>indole>quinoline>carbazole in terms of their degradation rates. Quantitative structure-biodegradability relationship studies of the five NHCs showed that the anoxic degradation rates were correlated well with highest occupied molecular orbital. Additionally, the active sites of NHCs identified by calculation were confirmed by analysis of intermediates using gas chromatography and mass spectrometry. Copyright © 2015. Published by Elsevier B.V.

Recycling and burial of phosphorus in sediments of an anoxic fjord-the By Fjord, western Sweden

DEFF Research Database (Denmark)

Viktorsson, Lena; Kononets, Mikhail; Roos, Per

2013-01-01

Recycling and burial of sediment phosphorus were studied in the By Fjord, western Sweden, during the years 2009 to 2010 using autonomous benthic landers and sediment sampling. The By Fjord is a small fjord with a shallow sill at its narrow mouth, which limits water exchange of the fjord's basin...... water. The water in the basin is exchanged only every 3 to 5 years and the water below sill level is anoxic or sulfidic between water renewals. Five sites were examined in the By Fjord; three shallow sites above the sill level with oxic bottom waters and two deeper sites with anoxic bottom waters...... anoxic site were also examined in the adjacent Koljo Fjord having similar characteristics as the By Fjord. In situ measurements of benthic fluxes of dissolved inorganic phosphorus (DIP) showed that the fluxes from sediments with oxic overlying water (0.05-0.23 mmol m(-2) d(-1)) were much lower than...

Climate of the Arctic marine environment.

Science.gov (United States)

Walsh, John E

2008-03-01

The climate of the Arctic marine environment is characterized by strong seasonality in the incoming solar radiation and by tremendous spatial variations arising from a variety of surface types, including open ocean, sea ice, large islands, and proximity to major landmasses. Interannual and decadal-scale variations are prominent features of Arctic climate, complicating the distinction between natural and anthropogenically driven variations. Nevertheless, climate models consistently indicate that the Arctic is the most climatically sensitive region of the Northern Hemisphere, especially near the sea ice margins. The Arctic marine environment has shown changes over the past several decades, and these changes are part of a broader global warming that exceeds the range of natural variability over the past 1000 years. Record minima of sea ice coverage during the past few summers and increased melt from Greenland have important implications for the hydrographic regime of the Arctic marine environment. The recent changes in the atmosphere (temperature, precipitation, pressure), sea ice, and ocean appear to be a coordinated response to systematic variations of the large-scale atmospheric circulation, superimposed on a general warming that is likely associated with increasing greenhouse gases. The changes have been sufficiently large in some sectors (e.g., the Bering/Chukchi Seas) that consequences for marine ecosystems appear to be underway. Global climate models indicate an additional warming of several degrees Celsius in much of the Arctic marine environment by 2050. However, the warming is seasonal (largest in autumn and winter), spatially variable, and closely associated with further retreat of sea ice. Additional changes predicted for 2050 are a general decrease of sea level pressure (largest in the Bering sector) and an increase of precipitation. While predictions of changes in storminess cannot be made with confidence, the predicted reduction of sea ice cover will

Plutonium behavior during the early diagenesis of marine sediments: applications to two marine environments labelled by radionuclides released from reprocessing plants; Etude du comportement du plutonium au cours de la diagenese precoce des sediments marins: applications a deux environnements marins marques par les rejets issus d'usines de retraitement de combustibles uses

Energy Technology Data Exchange (ETDEWEB)

Gouzy, A

2004-12-15

The plutonium released into the English Channel and the Irish Sea by nuclear fuel reprocessing plants is mainly associated to sediments. Nevertheless, this association is partially reversible. This work combines a field study, carried out on the Cumbrian mud patch and the Esk estuary (Eastern Irish Sea), and laboratory experiments performed on carbonaceous coarse-grained sediments collected in the Central Channel. It presents new data on the plutonium solid partition in sediments and suggests realistic scenarios for describing its release from sediments to the water column. The role of reactive sulphides acting as temporary sink phases is shown in anoxic sediments; those sulphides are liable to release dissolved plutonium upon their oxidation. The plutonium is also bound to carbonates within the carbonaceous matrix and as carbonate surface complexes. Conceptual schemes of the behaviour of the plutonium in marine sediments are proposed; they highlight the strong remobilization potential of plutonium from marine sediments to the interstitial water. Its plutonium content can be injected into the overlying water column. (author)

Plutonium behavior during the early diagenesis of marine sediments: applications to two marine environments labelled by radionuclides released from reprocessing plants; Etude du comportement du plutonium au cours de la diagenese precoce des sediments marins: applications a deux environnements marins marques par les rejets issus d'usines de retraitement de combustibles uses

Energy Technology Data Exchange (ETDEWEB)

Gouzy, A

2004-12-15

The plutonium released into the English Channel and the Irish Sea by nuclear fuel reprocessing plants is mainly associated to sediments. Nevertheless, this association is partially reversible. This work combines a field study, carried out on the Cumbrian mud patch and the Esk estuary (Eastern Irish Sea), and laboratory experiments performed on carbonaceous coarse-grained sediments collected in the Central Channel. It presents new data on the plutonium solid partition in sediments and suggests realistic scenarios for describing its release from sediments to the water column. The role of reactive sulphides acting as temporary sink phases is shown in anoxic sediments; those sulphides are liable to release dissolved plutonium upon their oxidation. The plutonium is also bound to carbonates within the carbonaceous matrix and as carbonate surface complexes. Conceptual schemes of the behaviour of the plutonium in marine sediments are proposed; they highlight the strong remobilization potential of plutonium from marine sediments to the interstitial water. Its plutonium content can be injected into the overlying water column. (author)

A comparative study of methanol as a supplementary carbon source for enhancing denitrification in primary and secondary anoxic zones.

Science.gov (United States)

Ginige, Maneesha P; Bowyer, Jocelyn C; Foley, Leah; Keller, Jürg; Yuan, Zhiguo

2009-04-01

A comparative study on the use of methanol as a supplementary carbon source to enhance denitrification in primary and secondary anoxic zones is reported. Three lab-scale sequencing batch reactors (SBR) were operated to achieve nitrogen and carbon removal from domestic wastewater. Methanol was added to the primary anoxic period of the first SBR, and to the secondary anoxic period of the second SBR. No methanol was added to the third SBR, which served as a control. The extent of improvement on the denitrification performance was found to be dependent on the reactor configuration. Addition to the secondary anoxic period is more effective when very low effluent nitrate levels are to be achieved and hence requires a relatively large amount of methanol. Adding a small amount of methanol to the secondary anoxic period may cause nitrite accumulation, which does not improve overall nitrogen removal. In the latter case, methanol should be added to the primary anoxic period. The addition of methanol can also improve biological phosphorus removal by creating anaerobic conditions and increasing the availability of organic carbon in wastewater for polyphosphate accumulating organisms. This potentially provides a cost-effective approach to phosphorus removal from wastewater with a low carbon content. New fluorescence in situ hybridisation (FISH) probes targeting methanol-utilising denitrifiers were designed using stable isotope probing. Microbial structure analysis of the sludges using the new and existing FISH probes clearly showed that the addition of methanol stimulated the growth of specific methanol-utilizing denitrifiers, which improved the capability of sludge to use methanol and ethanol for denitrification, but reduced its capability to use wastewater COD for denitrification. Unlike acetate, long-term application of methanol has no negative impact on the settling properties of the sludge.

Differential modification of oxic and anoxic radiation damage by chemicals. I. Simulation of the action of caffeine by certain inorganic radical scavengers

International Nuclear Information System (INIS)

Kesavan, P.C.; Sharma, G.J.; Afzal, S.M.J.

1978-01-01

Caffeine affords partial radioprotection against oxic damage, but potentiates anoxic damage in dry as well as presoaked barley seeds. Since our earlier studies have implicated a physicochemical pathway of action for such differential modification by caffeine, the effect of inorganic substances, known to scavenge specific categories of free radicals, on the oxic and anoxic components of radiation damage was investigated. It is found that the radiation-induced oxic damage is significantly reduced by potassium permanganate, potassium iodide, potassium nitrate, and potassium ferrocyanide which scavenge predominantly .H + e - /sub aq/, .OH, e - /sub aq/, and .OH radicals, respectively. Each of these four substances, like caffeine, also potentiates anoxic damage in dry seeds, but the anoxic damage in presoaked seeds is potentiated only by potassium ferrocyanide. These results do not confirm the view in the literature that the anoxic sensitization is largely mediated by .OH radicals. A discussion of these observations and the validity of comparing our seed data with those derived from experiments with bacterial spores and ''naked'' DNA solutions is presented

Anoxic monimolimnia: Nutrients devious feeders or bombs ready to explode?

Science.gov (United States)

Gianni, Areti; Zacharias, Ierotheos

2015-04-01

Coastal regions are under strong human influence and its environmental impact is reflected into their water quality. Oligotrophic estuaries and coastal systems have changed in mesotrophic and/or eutrophic, shown an increase in toxic algal blooms, hypoxic/anoxic events, and massive mortalities of many aquatic and benthic organisms. In strongly stratified and productive water basins, bottom water dissolved oxygen is depleted due to the excessive organic matter decomposition in these depths. Distribution and recycling of nutrients in their water column is inextricably dependent on oxygenation and redox conditions. Bottom water anoxia accelerates PO43-, NH4+ and H2S recycling and accumulation from organic matter decomposition. The anoxic, H2S, PO43- and NH4+ rich bottom water constitutes a toxic layer, threatening the balance of the entire ecosystem. In permanently stratified water basins, storm events could result in stratification destruction and water column total mixing. The turnover brings large amounts of H2S to the surface resulting in low levels of oxygen and massive fish kills. PO43- and NH4+ are released to the interface and surface waters promoting algal blooms. Μore organic matter is produced fueling anoxia. The arising question is, whether the balance of an anoxic water ecosystem is under the threat of its hypolimnetic nutrient and sulfide load, only in the case of storm events and water column total mixing. In polymictic water basins it is clear that the accumulated, in the bottom layer, nutrients will supply surface waters, after the pycnocline overturn. Besides this mechanism of basins' water quality degradation is nowadays recognized as one of the biggest obstacles in eutrophic environments management and restoration efforts. The role of internal load, in permanently stratified water basins, is not so clear. In the present study the impact of storm events on water column stability and bottom water anoxia of meromictic coastal basins, is investigated

PNAS Plus: Origin of first cells at terrestrial, anoxic geothermal fields

Science.gov (United States)

Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

2012-04-01

All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energy-dependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hence, the ion composition of modern cells might reflect the inorganic ion composition of the habitats of protocells. We attempted to reconstruct the "hatcheries" of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells. These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, and phosphate. Thus, protocells must have evolved in habitats with a high K+/Na+ ratio and relatively high concentrations of Zn, Mn, and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under the anoxic, CO2-dominated primordial atmosphere, the chemistry of basins at geothermal fields would resemble the internal milieu of modern cells. The precellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapor that were lined with porous silicate minerals mixed with metal sulfides and enriched in K+, Zn2+, and phosphorous compounds.

Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments

DEFF Research Database (Denmark)

Schippers, A.; Jørgensen, BB

2002-01-01

as substrates and NO3- as electron acceptor, in the presence of (FeS2)-Fe-55, to test for co-oxidation of FeS2, but an anaerobic microbial dissolution of (FeS2)-Fe-55, could not been detected. FeS2 and FeS were not oxidized by amorphous Fe(III) oxide in the presence of Fe-complexing organic compounds......Pyrite (FeS2) and iron monosulfide (FeS) play a central role in the sulfur and iron cycles of marine sediments, They may be buried in the sediment or oxidized by O-2 after transport by bioturbation to the sediment surface. FeS2 and FeS may also be oxidized within the anoxic sediment in which NO3...... marine sediments and incubated at different temperatures for > 1 yr. Bacteria could not be enriched with FeS2 as substrate or with FeS and amorphous Fe(III) oxide. With FeS and NO3-, 14 enrichments were obtained. One of these enrichments was further cultivated anaerobically with Fe2+ and S-0...

Freshwater savings from marine protein consumption

International Nuclear Information System (INIS)

Gephart, Jessica A; Pace, Michael L; D’Odorico, Paolo

2014-01-01

Marine fisheries provide an essential source of protein for many people around the world. Unlike alternative terrestrial sources of protein, marine fish production requires little to no freshwater inputs. Consuming marine fish protein instead of terrestrial protein therefore represents freshwater savings (equivalent to an avoided water cost) and contributes to a low water footprint diet. These water savings are realized by the producers of alternative protein sources, rather than the consumers of marine protein. This study quantifies freshwater savings from marine fish consumption around the world by estimating the water footprint of replacing marine fish with terrestrial protein based on current consumption patterns. An estimated 7 600 km 3  yr −1 of water is used for human food production. Replacing marine protein with terrestrial protein would require an additional 350 km 3  yr −1 of water, meaning that marine protein provides current water savings of 4.6%. The importance of these freshwater savings is highly uneven around the globe, with savings ranging from as little as 0 to as much as 50%. The largest savings as a per cent of current water footprints occur in Asia, Oceania, and several coastal African nations. The greatest national water savings from marine fish protein occur in Southeast Asia and the United States. As the human population increases, future water savings from marine fish consumption will be increasingly important to food and water security and depend on sustainable harvest of capture fisheries and low water footprint growth of marine aquaculture. (paper)

Avalanches of sediment form deep-marine depositions

NARCIS (Netherlands)

Pohl, Florian|info:eu-repo/dai/nl/34309424X

2017-01-01

The deep ocean is the largest sedimentary system basin on the planet. It serves as the primary storage point for all terrestrially weathered sediment that makes it beyond the near-shore environment. These deep-marine offshore deposits have become a focus of attention in exploration due to the

Effective bioremediation strategy for rapid in situ cleanup of anoxic marine sediments in mesocosm oil spill simulation.

Directory of Open Access Journals (Sweden)

Maria eGenovese

2014-04-01

Full Text Available The purpose of present study was the simulation of an oil spill accompanied by burial of significant amount of petroleum hydrocarbons (PHs in coastal sediments. Approximately 1,000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6,500 ppm. The rapid consumption of oxygen by aerobic heterotrophs created highly reduced conditions in the sediments with subsequent recession of biodegradation rates. As follows, after three months of ageing, the anaerobic sediments did not exhibit any significant levels of biodegradation and more than 80% of added Bunker C fuel oil remained buried. Anaerobic microbial community exhibited a strong enrichment in sulfate-reducing PHs-degrading and PHs-associated Deltaproteobacteria. As an effective bioremediation strategy to clean up these contaminated sediments, we applied a Modular Slurry System (MSS allowing the containment of sediments and their physical-chemical treatment, e.g. aeration. Aeration for three months has increased the removal of main PHs contaminants up to 98%. As revealed by CARD-FISH, qPCR and 16S rRNA gene clone library analyses, addition of Bunker C fuel oil initially affected the activity of autochthonous aerobic obligate marine hydrocarbonoclastic bacteria (OMHCB, and after one month more than the third of microbial population was represented by Alcanivorax-, Cycloclasticus- and Marinobacter-related organisms. In the end of the experiment, the microbial community composition has returned to a status typically observed in pristine marine ecosystems with no detectable OMHCB present. Eco-toxicological bioassay revealed that the toxicity of sediments after treatment was substantially decreased. Thus, our studies demonstrated that petroleum-contaminated anaerobic marine sediments could efficiently be cleaned through an in situ oxygenation which stimulates their self-cleaning potential due to reawakening of allochtonous aerobic OMHCB.

Hydrobiogeochemical interactions in 'anoxic' limestone drains for neutralization of acidic mine drainage

Science.gov (United States)

Robbins, E.I.; Cravotta, C.A.; Savela, C.E.; Nord, G.L.

1999-01-01

Processes affecting neutralization of acidic coal mine drainage were evaluated within 'anoxic' limestone drains (ALDs). Influents had pH???3.5 and dissolved oxygen treatment step is indicated to promote Al removal before diverting acidic mine water into alkalinity-producing materials. ?? 1998 Elsevier Science Ltd.

Increased Intracranial Pressure during Hemodialysis in a Patient with Anoxic Brain Injury

DEFF Research Database (Denmark)

Lund, Anton; Damholt, Mette B; Strange, Ditte G

2017-01-01

Dialysis disequilibrium syndrome (DDS) is a serious neurological complication of hemodialysis, and patients with acute brain injury are at increased risk. We report a case of DDS leading to intracranial hypertension in a patient with anoxic brain injury and discuss the subsequent dialysis strateg...

Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets.

Science.gov (United States)

Domagal-Goldman, Shawn D; Meadows, Victoria S; Claire, Mark W; Kasting, James F

2011-06-01

We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.

Impacts of discarded plastic bags on marine assemblages and ecosystem functioning.

Science.gov (United States)

Green, Dannielle Senga; Boots, Bas; Blockley, David James; Rocha, Carlos; Thompson, Richard

2015-05-05

The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide.

Microbiological reduction of Sb(V) in anoxic freshwater sediments

Science.gov (United States)

Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

2014-01-01

Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

Marine fishery possibilities of the west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Panikkar, N.K.

Marine fishery activity of the west coast of India is discussed. Sea fish production from the west coast of India makes three fourths of total fish production from Indian coasts. Kerala accounts for the largest production of fish in India...

A marine microbial consortium apparently mediating anaerobic oxidation of methane

DEFF Research Database (Denmark)

Boetius, A.; Ravenschlag, K.; Schubert, CJ

2000-01-01

microorganisms mediating this reaction have not yet been isolated, and the pathway of anaerobic oxidation of methane is insufficiently understood. Recent data suggest that certain archaea reverse the process of methanogenesis by interaction with sulphate-reducing bacteria(5-7). Here we provide microscopic...... cells and are surrounded by sulphate-reducing bacteria. These aggregates were abundant in gas-hydrate-rich sediments with extremely high rates of methane-based sulphate reduction, and apparently mediate anaerobic oxidation of methane.......A large fraction of globally produced methane is converted to CO2 by anaerobic oxidation in marine sediments(1). Strong geochemical evidence for net methane consumption in anoxic sediments is based on methane profiles(2), radiotracer experiments(3) and stable carbon isotope data(4). But the elusive...

Leatherback sea turtle stewardship to attain local, regional, and global marine conservation and management

Science.gov (United States)

Randall Arauz; Todd Steiner

2007-01-01

The leatherback sea turtle (Dermochelys coriacea) is the largest marine reptile with one of the longest known ocean migrations in the world and an important part of marine biodiversity. It is also important to the economies of coastal communities in developing countries, especially in areas where eco-tourism has replaced unsustainable harvest and...

Paleoclimatic and paleoceanographic studies of estuarine and marine sediments using strontium isotopes

International Nuclear Information System (INIS)

Ingram, B.L.

1992-01-01

Strontium isotopic ratio ( 87 Sr/ 86 Sr) measurements in fossil carbonates and phosphates are used to evaluate paleoceanographic and paleoclimatic environments in Quaternary, Pliocene-Pleistocene, and mid-Cretaceous estuarine and marine sediments. The use of 87 Sr/ 86 Sr measurements as an estuarine paleosalinity and paleoclimatic indicator is developed and applied to San Francisco Bay. 87 Sr/ 86 Sr measurements of foraminifer and molluscan fossils contained in estuarine sediments of late Pleistocene (ca 115 to 125 ka) and late Holocene (4.5 ka) age show cyclic variations indicating that salinity fluctuated with periods of several hundred years, probably reflecting wet-dry cycles associated with fluctuations in solar irradiance caused by sunspot cycles. The average salinity in San Pablo and Richardson bays was significantly lower (by 6 to 8%) over much of the past 4.5 ka than at present, reflecting a combination of decreased freshwater inflow at present associated with water diversion and wetter climatic conditions prior to 2000 years ago. Salinity data are converted to river discharge using salinity-delta flow relations derived from historical records for San Francisco Bay. The data indicate that annual freshwater inflow was at least twice the modern pre-diversion average between 2.5 and 3.0 Ka; this time period is also identified as one of wetter climatic conditions by lake level and treeline records from the Sierra Nevada. Strontium isotopic measurements of marine carbonate and fish teeth to middle Cretaceous age are used to increase the resolution of the existing seawater Sr isotope versus time curve and to assess models for global oceanic anoxic events. The new data using fish teeth show less scatter and variability than previous data. Negative excursions in the 87 Sr/ 86 Sr ratio of 7-14 parts in 10 -5 during Aptian anoxic events suggest a link between increased submarine volcanism and oceanic anoxia

Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin

Science.gov (United States)

Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.

2018-04-01

Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.

Oceanic Anoxic Event 1b: insights and new data from the Poggio le Guaine section (Umbria-Marche Basin)

Science.gov (United States)

Sabatino, Nadia; Sprovieri, Mario; Coccioni, Rodolfo; Salvagio Manta, Daniela; Gardin, Silvia; Baudin, François

2015-04-01

The upper Aptian to lower Albian interval (~114-109 Ma) represents a crucial period during Earth's history, with a major evolution in the nature of mid-Cretaceous tectonics, sea level, climate, and marine plankton communities. Interestingly, it also includes multiple prominent black shale horizons that are the sedimentary expression of oceanic anoxic event (OAE) 1b. An high-resolution planktonic foraminiferal and calcareous nannofossil biostratigraphy in combination with an integrated study of multiple geochemical proxies (δ13Ccarb, δ13Corg, TOC, HI, CaCO3, trace elements/Al ratios) of the late Aptian-early Albian OAE 1b has been performed on the pelagic sedimentary sequence of Poggio le Guaine (Umbria-Marche Basin, central Italy). A comparison of the newly collected stable isotope carbon curve with the records from the Vocontian Basin (SE France), DSDP Site 545 and Hole 1049C provided a reliable and precise identification of the four main prominent black shale levels (113/Jacob, Kilian, Urbino/Paquier and Leenhardt) that definitively punctuate the OAE 1b. The studied record shows an increase in the marine organic carbon accumulation rate, in particular in the 113/Jacob and Urbino/Paquier levels. In the other black shales, TOC values are metals. The results suggest an increase in organic carbon burial rates during the OAE 1b due to the effect of enhanced surface productivity, as supported by a major increase in Ba/Al, and reduced bottom water ventilation. Noteworthy, the Kilian and Urbino/Paquier levels from the PLG section are characterized by the absence of correlative shifts in δ13Ccarb and δ13Corg. The increase in the δ13Corg, values in these levels is explained by an increase in the relative contribution of δ13C enriched marine planktonic archaeal biomass, while the concomitant negative excursions recorded in the δ13Ccarb could reflect a major contribution of isotopically light terrestrial carbonate ions from increased continental runoff during

Poor outcome prediction by burst suppression ratio in adults with post-anoxic coma without hypothermia.

Science.gov (United States)

Yang, Qinglin; Su, Yingying; Hussain, Mohammed; Chen, Weibi; Ye, Hong; Gao, Daiquan; Tian, Fei

2014-05-01

Burst suppression ratio (BSR) is a quantitative electroencephalography (qEEG) parameter. The purpose of our study was to compare the accuracy of BSR when compared to other EEG parameters in predicting poor outcomes in adults who sustained post-anoxic coma while not being subjected to therapeutic hypothermia. EEG was registered and recorded at least once within 7 days of post-anoxic coma onset. Electrodes were placed according to the international 10-20 system, using a 16-channel layout. Each EEG expert scored raw EEG using a grading scale adapted from Young and scored amplitude-integrated electroencephalography tracings, in addition to obtaining qEEG parameters defined as BSR with a defined threshold. Glasgow outcome scales of 1 and 2 at 3 months, determined by two blinded neurologists, were defined as poor outcome. Sixty patients with Glasgow coma scale score of 8 or less after anoxic accident were included. The sensitivity (97.1%), specificity (73.3%), positive predictive value (82.5%), and negative prediction value (95.0%) of BSR in predicting poor outcome were higher than other EEG variables. BSR1 and BSR2 were reliable in predicting death (area under the curve > 0.8, P coma who do not undergo therapeutic hypothermia when compared to other qEEG parameters.

Ferrous archaeological analogues for the understanding of the multi-secular corrosion mechanisms in an anoxic environment

International Nuclear Information System (INIS)

Saheb-Djahromi, M.

2009-12-01

Understanding the long term corrosion mechanisms of iron in an anoxic environment is essential in the field of the radioactive waste storage. In France, it is planned to store high level nuclear wastes in a multi-barrier system containing a glassy matrix surrounded by a stainless steel container, embedded in a low-carbon steel over-container. This system would be placed in a deep geological repository, which would impose anoxic conditions. As it must be efficient for a period of several thousands of years, one should understand the alteration mechanisms that are expected to occur in such a long time. To this purpose, a specific approach is developed on ferrous archaeological analogues with thick corrosion layer formed in natural conditions. In this study, the corrosion mechanisms have been assessed by examining nails aged of 400 years coming from the archaeological site of Glinet, selected as a reference site. The first point was a fine characterisation of the entire corrosion system metal / corrosion products / medium, through the use of coupled multi-scale analytical tools. The first results showed that the samples were corroded in an anoxic calco-carbonated environment. Moreover, the coupling of X-ray micro-diffraction, Raman microspectroscopy and dispersive energy spectroscopy has enabled to identify three corrosion systems composed of iron carbonates, siderite and chukanovite, and magnetite. Depending on the phase's layout in the system, the electronic resistance of the corrosion layers has been established, from resistive to conductive. In a second stage, re-corroding experiments in laboratory were performed. Firstly, the electrochemical behaviour of the corrosion system has shown that water reduction at the metallic interface is negligible. Furthermore, reaction tracing with copper and deuterium has allowed identifying the electron consumptions sites mainly localised on the external part, and the precipitation sites on the internal part of the corrosion

First Insights into the Viral Communities of the Deep-sea Anoxic Brines of the Red Sea

KAUST Repository

Antunes, Andre

2015-10-31

The deep-sea brines of the Red Sea include some of the most extreme and unique environments on Earth. They combine high salinities with increases in temperature, heavy metals, hydrostatic pressure, and anoxic conditions, creating unique settings for thriving populations of novel extremophiles. Despite a recent increase of studies focusing on these unusual biotopes, their viral communities remain unexplored. The current survey explores four metagenomic datasets obtained from different brine-seawater interface samples, focusing specifically on the diversity of their viral communities. Data analysis confirmed that the particle-attached viral communities present in the brine-seawater interfaces were diverse and generally dominated by Caudovirales, yet appearing distinct from sample to sample. With a level of caution, we report the unexpected finding of Phycodnaviridae, which infects algae and plants, and trace amounts of insect-infecting Iridoviridae. Results from Kebrit Deep revealed stratification in the viral communities present in the interface: the upper-interface was enriched with viruses associated with typical marine bacteria, while the lower-interface was enriched with haloviruses and halophages. These results provide first insights into the unexplored viral communities present in deep-sea brines of the Red Sea, representing one of the first steps for ongoing and future sampling efforts and studies.

First Insights into the Viral Communities of the Deep-sea Anoxic Brines of the Red Sea

KAUST Repository

Antunes, Andre; Alam, Intikhab; Simoes, Marta; Daniels, Camille Arian; Ferreira, Ari J.S.; Siam, Rania; El-Dorry, Hamza; Bajic, Vladimir B.

2015-01-01

The deep-sea brines of the Red Sea include some of the most extreme and unique environments on Earth. They combine high salinities with increases in temperature, heavy metals, hydrostatic pressure, and anoxic conditions, creating unique settings for thriving populations of novel extremophiles. Despite a recent increase of studies focusing on these unusual biotopes, their viral communities remain unexplored. The current survey explores four metagenomic datasets obtained from different brine-seawater interface samples, focusing specifically on the diversity of their viral communities. Data analysis confirmed that the particle-attached viral communities present in the brine-seawater interfaces were diverse and generally dominated by Caudovirales, yet appearing distinct from sample to sample. With a level of caution, we report the unexpected finding of Phycodnaviridae, which infects algae and plants, and trace amounts of insect-infecting Iridoviridae. Results from Kebrit Deep revealed stratification in the viral communities present in the interface: the upper-interface was enriched with viruses associated with typical marine bacteria, while the lower-interface was enriched with haloviruses and halophages. These results provide first insights into the unexplored viral communities present in deep-sea brines of the Red Sea, representing one of the first steps for ongoing and future sampling efforts and studies.

The marine ecosystems of the South Pacific coast of Costa Rica: state of knowledge and management perspectives

International Nuclear Information System (INIS)

Quesada Alpizar, Marco A.; Cortes, Jorge

2006-01-01

A review of the existing scientific literature on marine ecosystems in the South Pacific of Costa Rica is presented. Most of the information generated to date concentrates on the Golfo Dulce area, a tropical fiord and only anoxic basin in the American pacific coast. Even thought there is a considerable amount of information available, there are still many aspects of the marine ecosystems of the region that remain unstudied. Among these, those concerning circulation patterns, mangrove dynamics, biodiversity of soft sediments and deep waters, and the ecology of commercially important species of mollusks, crustaceans and fish, stand out. Special attention should be placed on the study of Golfo Dulce, Isla del Cano and the Terraba-Sierpe mangrove system, give their biological importance and unique regional character. Coastal management in the region should be based on the best scientific information available integrating biological, social and economic criteria; and seeking the improvement of inter-institutional coordination in order to achieve integrative solutions to the existing threats to marine resources. (author) [es

Modification of radiation-induced oxic and anoxic damage by caffeine and potassium permanganate in barley seeds

International Nuclear Information System (INIS)

Kesavan, P.C.; Dodd, N.J.F.

1976-01-01

It has been demonstrated that both the immediate and post-irradiation oxygen effects in barley seeds decrease in magnitude in the presence of potassium permanganate and caffeine. This implied that these two types of oxygen effect have features in common. With the removal of the radiation-induced oxygen-sensitive sites, by anoxic hydration, caffeine potentiated the oxygen-independent component of damage, in seeds irradiated in a dry or pre-soaked state. Potassium permanganate, on the other hand, enhanced the anoxic radiation damage only in seeds irradiated in a dry state. The possible mode of action of KMnO 4 and caffeine in barley seeds is discussed. (author)

Biological Phosphorus Release and Uptake Under Alternating Anaerobic and Anoxic Conditions In a Fixed-Film Reactor

DEFF Research Database (Denmark)

Kerrn-Jespersen, Jens Peter; Henze, Mogens; Strube, Rune

1994-01-01

Biological phosphorus removal was investigated in a fixed-film reactor with alternating anaerobic and anoxic conditions. The tests showed that biological phosphorus removal can be obtained in a fixed-film reactor with nitrate as oxidising agent. In the anaerobic period, 0.52 mg of PO4-P...... was released per mg of acetate taken up on an average. In the anoxic period, 2.0 mg of PO4-P was taken up per mg of NO3-N reduced on an average. The relationship between potassium released and phosphate released in the anaerobic phase was determined to be 0.37 mg K/mg P, while the relationship between...

Multi-secular corrosion behaviour of low carbon steel in anoxic soils: Characterisation of corrosion system on archaeological artefacts

International Nuclear Information System (INIS)

Saheb, M.; Neff, D.; Dillmann, P.; Foy, E.; Saheb, M.; Dillmann, P.; Matthiesen, H.; Bellot-Gurlet, L.

2009-01-01

In the context of the prediction of materials behaviour used in the nuclear waste storage, the understanding of iron corrosion mechanisms in anoxic environment is of great importance. Information can be obtained using complementary analytical tools. Interactions between burial soil and archaeological artefacts are studied by performing on site soil measurements. Moreover, archaeological artefacts are studied on transverse sections using a combination of microbeam techniques. The specific interest of this project lies in the study of ferrous thick corrosion layers formed in anoxic environment. (authors)

Complete nitrogen removal from municipal wastewater via partial nitrification by appropriately alternating anoxic/aerobic conditions in a continuous plug-flow step feed process.

Science.gov (United States)

Ge, Shijian; Peng, Yongzhen; Qiu, Shuang; Zhu, Ao; Ren, Nanqi

2014-05-15

This study assessed the technical feasibility of removing nitrogen from municipal wastewater by partial nitrification (nitritation) in a continuous plug-flow step feed process. Nitrite in the effluent accumulated to over 81.5  ± 9.2% but disappeared with the transition of process operation from anoxic/oxic mode to the anaerobic/anoxic/oxic mode. Batch tests showed obvious ammonia oxidizing bacteria (AOB) stimulation (advanced ammonia oxidation rate) and nitrite (NOB) oxidizing bacteria inhibition (reduced nitrite oxidation rate) under transient anoxic conditions. Two main factors contributed to nitritation in this continuous plug-flow process: One was the alternating anoxic and oxic operational condition; the step feed strategy guaranteed timely denitrification in anoxic zones, allowing a reduction in energy supply (nitrite) to NOB. Fluorescence in Situ Hybridization and quantitative real-time polymerase chain reaction analysis indicated that NOB population gradually decreased to 1.0  ± 0.1% of the total bacterial population (dominant Nitrospira spp., 1.55 × 10(9) copies/L) while AOB increased approximately two-fold (7.4  ± 0.9%, 1.25 × 10(10) copies/L) during the above anoxic to anaerobic transition. Most importantly, without addition of external carbon sources, the above wastewater treatment process reached 86.0  ± 4.2% of total nitrogen (TN) removal with only 7.23 ± 2.31 mg/L of TN in the effluent, which met the discharge requirements. Copyright © 2014 Elsevier Ltd. All rights reserved.

Viral lysis of marine microbes in relation to vertical stratification

NARCIS (Netherlands)

Mojica, K.D.A.

2015-01-01

Marine microorganisms represent the largest reservoir of living organic carbon in the ocean and collectively manage the pools and fluxes of nutrients and energy. Climate-induced increases in sea surface temperature and associated modifications to vertical stratification are affecting the structure

An Overview of Marine Biodiversity in United States Waters

Science.gov (United States)

Fautin, Daphne; Dalton, Penelope; Incze, Lewis S.; Leong, Jo-Ann C.; Pautzke, Clarence; Rosenberg, Andrew; Sandifer, Paul; Sedberry, George; Tunnell, John W.; Abbott, Isabella; Brainard, Russell E.; Brodeur, Melissa; Eldredge, Lucius G.; Feldman, Michael; Moretzsohn, Fabio; Vroom, Peter S.; Wainstein, Michelle; Wolff, Nicholas

2010-01-01

Marine biodiversity of the United States (U.S.) is extensively documented, but data assembled by the United States National Committee for the Census of Marine Life demonstrate that even the most complete taxonomic inventories are based on records scattered in space and time. The best-known taxa are those of commercial importance. Body size is directly correlated with knowledge of a species, and knowledge also diminishes with distance from shore and depth. Measures of biodiversity other than species diversity, such as ecosystem and genetic diversity, are poorly documented. Threats to marine biodiversity in the U.S. are the same as those for most of the world: overexploitation of living resources; reduced water quality; coastal development; shipping; invasive species; rising temperature and concentrations of carbon dioxide in the surface ocean, and other changes that may be consequences of global change, including shifting currents; increased number and size of hypoxic or anoxic areas; and increased number and duration of harmful algal blooms. More information must be obtained through field and laboratory research and monitoring that involve innovative sampling techniques (such as genetics and acoustics), but data that already exist must be made accessible. And all data must have a temporal component so trends can be identified. As data are compiled, techniques must be developed to make certain that scales are compatible, to combine and reconcile data collected for various purposes with disparate gear, and to automate taxonomic changes. Information on biotic and abiotic elements of the environment must be interactively linked. Impediments to assembling existing data and collecting new data on marine biodiversity include logistical problems as well as shortages in finances and taxonomic expertise. PMID:20689852

An overview of marine biodiversity in United States waters

Science.gov (United States)

Fautin, Daphne G.; Delton, Penelope; Incze, Lewis S.; Leong, Jo-Ann C.; Pautzke, Clarence; Rosenberg, Andrew A.; Sandifer, Paul; Sedberry, George R.; Tunnell, John W.; Abbott, Isabella; Brainard, Russell E.; Brodeur, Melissa; Eldredge, Lucius G.; Feldman, Michael; Moretzsohn, Fabio; Vroom, Peter S.; Wainstein, Michelle; Wolff, Nicholas

2010-01-01

Marine biodiversity of the United States (U.S.) is extensively documented, but data assembled by the United States National Committee for the Census of Marine Life demonstrate that even the most complete taxonomic inventories are based on records scattered in space and time. The best-known taxa are those of commercial importance. Body size is directly correlated with knowledge of a species, and knowledge also diminishes with distance from shore and depth. Measures of biodiversity other than species diversity, such as ecosystem and genetic diversity, are poorly documented. Threats to marine biodiversity in the U.S. are the same as those for most of the world: overexploitation of living resources; reduced water quality; coastal development; shipping; invasive species; rising temperature and concentrations of carbon dioxide in the surface ocean, and other changes that may be consequences of global change, including shifting currents; increased number and size of hypoxic or anoxic areas; and increased number and duration of harmful algal blooms. More information must be obtained through field and laboratory research and monitoring that involve innovative sampling techniques (such as genetics and acoustics), but data that already exist must be made accessible. And all data must have a temporal component so trends can be identified. As data are compiled, techniques must be developed to make certain that scales are compatible, to combine and reconcile data collected for various purposes with disparate gear, and to automate taxonomic changes. Information on biotic and abiotic elements of the environment must be interactively linked. Impediments to assembling existing data and collecting new data on marine biodiversity include logistical problems as well as shortages in finances and taxonomic expertise.

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers

International Nuclear Information System (INIS)

Stelzer, Nicole; Imfeld, Gwenael; Thullner, Martin; Lehmann, Juergen; Poser, Alexander; Richnow, Hans-H.; Nijenhuis, Ivonne

2009-01-01

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of 13 C, which complicates the evaluation of degradation. Therefore, the compound-specific isotope analysis was interpreted based on an isotope balance. The enrichment of the cumulative isotope composition of all chlorobenzenes indicated in situ biodegradation. Additionally, the relationship between hydrogeochemistry and degradation activity was investigated by principal component analysis underlining variable hydrogeochemical conditions associated with degradation activity at the plume scale. Although the complexity of the field site did not allow straightforward assessment of natural attenuation processes, the application of an integrative approach appeared relevant to characterize the in situ biodegradation potential. - Lines of evidence for in situ biodegradation of chlorinated benzenes in an anoxic aquifer by combining hydrogeochemical and stable isotope data with multivariate statistics.

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers

Energy Technology Data Exchange (ETDEWEB)

Stelzer, Nicole; Imfeld, Gwenael [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Thullner, Martin [Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Lehmann, Juergen [Ingenieurbuero Roth and Partner GmbH, Hans-Sachs-Str. 9, 76133 Karlsruhe (Germany); Poser, Alexander [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Richnow, Hans-H., E-mail: hans.richnow@ufz.d [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Nijenhuis, Ivonne [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany)

2009-06-15

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of {sup 13}C, which complicates the evaluation of degradation. Therefore, the compound-specific isotope analysis was interpreted based on an isotope balance. The enrichment of the cumulative isotope composition of all chlorobenzenes indicated in situ biodegradation. Additionally, the relationship between hydrogeochemistry and degradation activity was investigated by principal component analysis underlining variable hydrogeochemical conditions associated with degradation activity at the plume scale. Although the complexity of the field site did not allow straightforward assessment of natural attenuation processes, the application of an integrative approach appeared relevant to characterize the in situ biodegradation potential. - Lines of evidence for in situ biodegradation of chlorinated benzenes in an anoxic aquifer by combining hydrogeochemical and stable isotope data with multivariate statistics.

Sulfide Oxidation in the Anoxic Black-Sea Chemocline

DEFF Research Database (Denmark)

JØRGENSEN, BB; FOSSING, H.; WIRSEN, CO

1991-01-01

per day, occurred in anoxic water at the top of the sulfide zone concurrent with the highest rates of dark CO2 assimilation. The main soluble oxidized products of sulfide were thiosulfate (68-82%) and sulfate. Indirect evidence was presented for the formation of elemental sulfur which accumulated...... that the measured H2S oxidation rates were 4-fold higher than could be explained by the downward flux of organic carbon and too high to balance the availability of electron acceptors such as oxidized iron or manganese. A nitrate maximum at the lower boundary of the O2 zone did not extend down to the sulfide zone....

Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

KAUST Repository

Beyer, Florian

2014-10-01

Long-term performance and fouling behavior of four full-scale nanofiltration (NF) plants, treating anoxic groundwater at 80% recovery for drinking water production, were characterized and compared with oxic NF and reverse osmosis systems. Plant operating times varied between 6 and 10 years and pretreatment was limited to 10μm pore size cartridge filtration and antiscalant dosage (2-2.5mgL-1) only. Membrane performance parameters normalized pressure drop (NPD), normalized specific water permeability (Kw) and salt retention generally were found stable over extended periods of operation (>6 months). Standard acid-base cleanings (once per year or less) were found to be sufficient to maintain satisfying operation during direct NF of the described iron rich (≤8.4mgL-1) anoxic groundwaters. Extensive autopsies of eight NF membrane elements, which had been in service since the plant startup (6-10 years), were performed to characterize and quantify the material accumulated in the membrane elements. Investigations using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), total organic carbon (TOC) and adenosine triphosphate (ATP) measurements revealed a complex mixture of organic, biological and inorganic materials. The fouling layers that developed during half to one year of operation without chemical cleaning were very thin (<2. μm). Most bio(organic) accumulates were found in the lead elements of the installations while inorganic precipitates/deposits (aluminosilicates and iron(II)sulfides) were found in all autopsied membrane elements. The high solubility of reduced metal ions and the very slow biofilm development under anoxic conditions prevented rapid fouling during direct NF of the studied groundwaters. When compared to oxic NF and RO systems in general (e.g. aerated ground waters or surface waters), the operation and performance of the described anoxic installations (with minimal pretreatment) can be described as very stable. © 2014

Abundant Trimethylornithine Lipids and Specific Gene Sequences Are Indicative of Planctomycete Importance at the Oxic/Anoxic Interface in Sphagnum-Dominated Northern Wetlands.

Science.gov (United States)

Moore, Eli K; Villanueva, Laura; Hopmans, Ellen C; Rijpstra, W Irene C; Mets, Anchelique; Dedysh, Svetlana N; Sinninghe Damsté, Jaap S

2015-09-01

Northern wetlands make up a substantial terrestrial carbon sink and are often dominated by decay-resistant Sphagnum mosses. Recent studies have shown that planctomycetes appear to be involved in degradation of Sphagnum-derived debris. Novel trimethylornithine (TMO) lipids have recently been characterized as abundant lipids in various Sphagnum wetland planctomycete isolates, but their occurrence in the environment has not yet been confirmed. We applied a combined intact polar lipid (IPL) and molecular analysis of peat cores collected from two northern wetlands (Saxnäs Mosse [Sweden] and Obukhovskoye [Russia]) in order to investigate the preferred niche and abundance of TMO-producing planctomycetes. TMOs were present throughout the profiles of Sphagnum bogs, but their concentration peaked at the oxic/anoxic interface, which coincided with a maximum abundance of planctomycete-specific 16S rRNA gene sequences. The sequences detected at the oxic/anoxic interface were affiliated with the Isosphaera group, while sequences present in the anoxic peat layers were related to an uncultured planctomycete group. Pyrosequencing-based analysis identified Planctomycetes as the major bacterial group at the oxic/anoxic interface at the Obukhovskoye peat (54% of total 16S rRNA gene sequence reads), followed by Acidobacteria (19% reads), while in the Saxnäs Mosse peat, Acidobacteria were dominant (46%), and Planctomycetes contributed to 6% of the total reads. The detection of abundant TMO lipids in planctomycetes isolated from peat bogs and the lack of TMO production by cultures of acidobacteria suggest that planctomycetes are the producers of TMOs in peat bogs. The higher accumulation of TMOs at the oxic/anoxic interface and the change in the planctomycete community with depth suggest that these IPLs could be synthesized as a response to changing redox conditions at the oxic/anoxic interface. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Damped trophic cascades driven by fishing in model marine ecosystems

DEFF Research Database (Denmark)

Andersen, Ken Haste; Pedersen, Martin

2010-01-01

The largest perturbation on upper trophic levels of many marine ecosystems stems from fishing. The reaction of the ecosystem goes beyond the trophic levels directly targeted by the fishery. This reaction has been described either as a change in slope of the overall size spectrum or as a trophic...... cascade triggered by the removal of top predators. Here we use a novel size- and trait-based model to explore how marine ecosystems might react to perturbations from different types of fishing pressure. The model explicitly resolves the whole life history of fish, from larvae to adults. The results show...... that fishing does not change the overall slope of the size spectrum, but depletes the largest individuals and induces trophic cascades. A trophic cascade can propagate both up and down in trophic levels driven by a combination of changes in predation mortality and food limitation. The cascade is damped...

Model photoautrophs isolated from a Proterozoic ocean analog - aerobic life under anoxic conditions

Science.gov (United States)

Hamilton, T. L.; de Beer, D.; Klatt, J.; Macalady, J.; Weber, M.; Lott, C.; Chennu, A.

2016-12-01

The 1-2 billion year delay before the final rise of oxygen at the end of the Proterozoic represents an important gap in our understanding of ancient biogeochemical cycling. Primary production fueled by sulfide-dependent anoxygenic photosynthesis, including the activity of metabolically versatile cyanobacteria, has been invoked as a mechanism for sustaining low atmospheric O2 throughout much of the Proterozoic. However, we understand very little about photoautotrophs that inhabit Proterozoic-like environments present on Earth today. Here we report on the isolation and characterization of a cyanobacterium and a green sulfur bacterium that are the dominant members of pinnacle mats in Little Salt Spring—a karst sinkhole in Florida with perennially low levels of dissolved oxygen and sulfide. The red pinnacle mats bloom in the anoxic basin of the sinkhole and receive light that is of very poor quality to support photosynthesis. Characterization of the isolates is consistent with observations of oxygenic and anoxygenic photosynthesis in situ—both organisms perform anoxygenic photosynthesis under conditions of very low light quality and quantity. Oxygenic photosynthesis by the cyanobacterium isolate is inhibited by the presence of sulfide and under optimal light conditions, rates of anoxygenic photosynthesis are nearly double that of oxygenic photosynthesis. The green sulfur bacterium is tolerant of oxygen and has a very low affinity for sulfide. In Little Salt Spring, oxygenic photosynthesis occurs for only four hours a day and the water column remains anoxic because of a continuous supply of sulfide. Isolation and characterization of these photoautotrophs combined with our high resolution microsensor data in situ highlight microbial biogeochemical cycling in this exceptional site where aerobic microorganisms persist in a largely anoxic ecosystem.

Metabolic profiling of heat or anoxic stress in mouse C2C12 myotubes using multinuclear magnetic resonance spectroscopy

DEFF Research Database (Denmark)

Straadt, Ida K; Young, Jette F; Petersen, Bent O

2010-01-01

to anaerobic metabolism due to inhibition of the aerobic pathway in the mitochondria. Conversely, lower levels of unlabeled ((12)C) lactate were apparent at increasing severity of stress, which indicate that lactate is released from the myotubes to the medium. In conclusion, the metabolites identified......In the present study, the metabolic effects of heat and anoxic stress in myotubes from the mouse cell line C2C12 were investigated by using a combination of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy and enrichment with [(13)C]-glucose. Both the (13)C and the (1)H NMR...... spectra showed reduced levels of the amino acids alanine, glutamate, and aspartate after heat or anoxic stress. The decreases were smallest at 42 degrees C, larger at 45 degrees C, and most pronounced after anoxic conditions. In addition, in both the (1)H and the (31)P NMR spectra, decreases in the high...

Arsenic in an alkaline AMD treatment sludge: Characterization and stability under prolonged anoxic conditions

International Nuclear Information System (INIS)

Beauchemin, Suzanne; Fiset, Jean-Francois; Poirier, Glenn; Ablett, James

2010-01-01

Lime treatment of acid mine drainage (AMD) generates large volumes of neutralization sludge that are often stored under water covers. The sludge consists mainly of calcite, gypsum and a widespread ferrihydrite-like Fe phase with several associated species of metal(loid) contaminants. The long-term stability of metal(loid)s in this chemically ill-defined material remains unknown. In this study, the stability and speciation of As in AMD sludge subjected to prolonged anoxic conditions is determined. The total As concentration in the sludge is 300 mg kg -1 . In the laboratory, three distinct water cover treatments were imposed on the sludge to induce different redox conditions (100%N 2 , 100%N 2 + glucose, 95%N 2 :5%H 2 ). These treatments were compared against a control of oxidized, water-saturated sludge. Electron micro-probe (EMP) analysis and spatially resolved synchrotron X-ray fluorescence (SXRF) results indicate that As is dominantly associated with Fe in the sludge. In all treatments and throughout the experiment, measured concentrations of dissolved As were less than 5 μg L -1 . Dissolved Mn concentration in the N 2 + glucose treatment increased significantly compared to other treatments. Manganese and As K-edge X-ray absorption near edge structure spectroscopy (XANES) analyses showed that Mn was the redox-active element in the solid-phase, while As was stable. Arsenic(V) was still the dominant species in all water-covered sludges after 9 months of anoxic treatments. In contrast, Mn(IV) in the original sludge was partially reduced into Mn(II) in all water-covered sludges. The effect was most pronounced in the N 2 + glucose treatment, suggesting microbial reduction. Micro-scale SXRF and XANES analysis of the treated sludge showed that Mn(II) accumulated in areas already enriched in Fe and As. Overall, the study shows that AMD sludges remain stable under prolonged anoxic conditions. External sources of chemical reductants or soluble C were needed to induce

First Insights into the Viral Communities of the Deep-sea Anoxic Brines of the Red Sea.

Science.gov (United States)

Antunes, André; Alam, Intikhab; Simões, Marta Filipa; Daniels, Camille; Ferreira, Ari J S; Siam, Rania; El-Dorry, Hamza; Bajic, Vladimir B

2015-10-01

The deep-sea brines of the Red Sea include some of the most extreme and unique environments on Earth. They combine high salinities with increases in temperature, heavy metals, hydrostatic pressure, and anoxic conditions, creating unique settings for thriving populations of novel extremophiles. Despite a recent increase of studies focusing on these unusual biotopes, their viral communities remain unexplored. The current survey explores four metagenomic datasets obtained from different brine-seawater interface samples, focusing specifically on the diversity of their viral communities. Data analysis confirmed that the particle-attached viral communities present in the brine-seawater interfaces were diverse and generally dominated by Caudovirales, yet appearing distinct from sample to sample. With a level of caution, we report the unexpected finding of Phycodnaviridae, which infects algae and plants, and trace amounts of insect-infecting Iridoviridae. Results from Kebrit Deep revealed stratification in the viral communities present in the interface: the upper-interface was enriched with viruses associated with typical marine bacteria, while the lower-interface was enriched with haloviruses and halophages. These results provide first insights into the unexplored viral communities present in deep-sea brines of the Red Sea, representing one of the first steps for ongoing and future sampling efforts and studies. Copyright © 2015 The Authors. Production and hosting by Elsevier Ltd.. All rights reserved.

Quantifying ingested debris in marine megafauna: a review and recommendations for standardization

OpenAIRE

Provencher, Jennifer F.; Bond, Alexander L.; Avery-gomm, Stephanie; Borrelle, Stephanie B.; Bravo Rebolledo, Elisa L.; Hammer, Sjúrður; Kühn, Suse; Lavers, Jennifer L.; Mallory, Mark L.; Trevail, Alice; Franeker, van, Jan A.

2017-01-01

Plastic pollution has become one of the largest environmental challenges we currently face. The United\\ud Nations Environment Program (UNEP) has listed it as a critical problem, comparable to climate change,\\ud demonstrating both the scale and degree of the environmental problem. Mortalities due to entanglement\\ud in plastic fishing nets and bags have been reported for marine mammals, turtles and seabirds, and to date\\ud over 690 marine species have been reported to ingest plastics. The body ...

Mariner 9 View of Arsia Silva

Science.gov (United States)

1971-01-01

Mariner 9 took this picture of Mars during the closing hours of its approach to the planet on November 13, 1971. The picture has been computer-enhanced with electronic high-pass filtering. The crater-like object at the lower left is about 124 miles (200 kilometers) across and is the same dark spot seen earlier in more distant views. It can be identified on a Mars map as Arsia Silva. The streaks pointing north--more than 1000 kilometers long--are either atmospheric turbulence patterns or dunes formed downwind of the crater. If they are dunes, they are as extensive as the largest in the Sahara in North Africa and those in Peru, South America. The picture was taken from a distance of 65,000 miles about eight hours before Mariner 9 went into orbit around Mars. It was transmitted back to Earth at 10:00 p.m. during the first orbit.Mariner 9 was the first spacecraft to orbit another planet. The spacecraft was designed to continue the atmospheric studies begun by Mariners 6 and 7, and to map over 70% of the Martian surface from the lowest altitude (1500 kilometers [900 miles])and at the highest resolutions (1 kilometer per pixel to 100 meters per pixel) of any previous Mars mission.Mariner 9 was launched on May 30, 1971 and arrived on November 14, 1971.

Cross-regulation by CrcZ RNA controls anoxic biofilm formation in Pseudomonas aeruginosa

Science.gov (United States)

Pusic, Petra; Tata, Muralidhar; Wolfinger, Michael T.; Sonnleitner, Elisabeth; Häussler, Susanne; Bläsi, Udo

2016-12-01

Pseudomonas aeruginosa (PA) can thrive in anaerobic biofilms in the lungs of cystic fibrosis (CF) patients. Here, we show that CrcZ is the most abundant PA14 RNA bound to the global regulator Hfq in anoxic biofilms grown in cystic fibrosis sputum medium. Hfq was crucial for anoxic biofilm formation. This observation complied with an RNAseq based transcriptome analysis and follow up studies that implicated Hfq in regulation of a central step preceding denitrification. CrcZ is known to act as a decoy that sequesters Hfq during relief of carbon catabolite repression, which in turn alleviates Hfq-mediated translational repression of catabolic genes. We therefore inferred that CrcZ indirectly impacts on biofilm formation by competing for Hfq. This hypothesis was supported by the findings that over-production of CrcZ mirrored the biofilm phenotype of the hfq deletion mutant, and that deletion of the crcZ gene augmented biofilm formation. To our knowledge, this is the first example where competition for Hfq by CrcZ cross-regulates an Hfq-dependent physiological process unrelated to carbon metabolism.

Sources and distribution of anthropogenic radionuclides in different marine environments

International Nuclear Information System (INIS)

Holm, E.

1997-01-01

The knowledge of the distribution in time and space radiologically important radionuclides from different sources in different marine environments is important for assessment of dose commitment following controlled or accidental releases and for detecting eventual new sources. Present sources from nuclear explosion tests, releases from nuclear facilities and the Chernobyl accident provide a tool for such studies. The different sources can be distinguished by different isotopic and radionuclide composition. Results show that radiocaesium behaves rather conservatively in the south and north Atlantic while plutonium has a residence time of about 8 years. On the other hand enhanced concentrations of plutonium in surface waters in arctic regions where vertical mixing is small and iceformation plays an important role. Significantly increased concentrations of plutonium are also found below the oxic layer in anoxic basins due to geochemical concentration. (author)

Effect of resuspension on the release of heavy metals and water chemistry in anoxic and oxic sediments

Energy Technology Data Exchange (ETDEWEB)

Hwang, Kyung-Yup; Kim, Hong-Seok; Hwang, Inseong [School of Civil and Environmental Engineering, Pusan National University, Busan (Korea, Republic of)

2011-10-15

Two types of river sediments with contrasting characteristics (anoxic or oxic) were resuspended and the release of heavy metals and changes in water chemistry were investigated. During resuspension of the anoxic sediment, the dissolved oxygen (DO) concentration and redox potential of the water layer decreased abruptly within the first 1 min, followed by increases toward the end of the resuspension period. Heavy metals were released rapidly in the first 6 h, probably due to the oxidation of acid volatile sulfide (AVS) of the anoxic sediment, and then the aqueous phase concentrations of the heavy metals decreased due to resorption onto the sediment until the 12-h point. During resuspension of the oxic sediment, the DO concentration and redox potential remained relatively constant in the oxic ranges. The heavy metals were released from the oxic sediment gradually during a 24-h resuspension period. The temporal maximum concentrations of Ni, Cu, Zn, and Cd in the aqueous phases in both experiments frequently exceeded the USEPA water quality criteria or the water quality guidelines of Australia and New Zealand. This suggests that a resuspension event could bring about temporal water quality deterioration in the two sediment environments. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Culture-dependent and independent studies of microbial diversity in highly copper-contaminated Chilean marine sediments.

Science.gov (United States)

Besaury, Ludovic; Marty, Florence; Buquet, Sylvaine; Mesnage, Valérie; Muyzer, Gerard; Quillet, Laurent

2013-02-01

Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions, focusing on sulfate-, thiosulfate-, and iron-reducing bacteria. For both sediments, the cultivable bacteria isolated at oxic conditions were mostly affiliated to the genus Bacillus, while at anoxic conditions the majority of the cultivable bacteria found were closely related to members of the genera Desulfovibrio, Sphingomonas, and Virgibacillus. Copper resistance was between 100 and 400 ppm, with the exception of a strain affiliated to members of the genus Desulfuromonas, which was resistant up to 1,000 ppm of copper. In parallel, cloning and sequencing of 16S rRNA was performed to study the total bacterial diversity in the sediments. A weak correlation was observed between the isolated strains and the 16S rRNA operational taxonomic units detected. The presence of copper resistance genes (copA, cusA, and pcoA) was tested for all the strains isolated; only copA was detected in a few isolates, suggesting that other copper resistance mechanisms could be used by the bacteria in those highly copper-contaminated sediments.

Denitrifying metabolism of the methylotrophic marine bacterium Methylophaga nitratireducenticrescens strain JAM1.

Science.gov (United States)

Mauffrey, Florian; Cucaita, Alexandra; Constant, Philippe; Villemur, Richard

2017-01-01

Methylophaga nitratireducenticrescens strain JAM1 is a methylotrophic, marine bacterium that was isolated from a denitrification reactor treating a closed-circuit seawater aquarium. It can sustain growth under anoxic conditions by reducing nitrate ([Formula: see text]) to nitrite ([Formula: see text]). These physiological traits are attributed to gene clusters that encode two dissimilatory nitrate reductases (Nar). Strain JAM1 also contains gene clusters encoding two nitric oxide (NO) reductases and one nitrous oxide (N 2 O) reductase, suggesting that NO and N 2 O can be reduced by strain JAM1. Here we characterized further the denitrifying activities of M. nitratireducenticrescens JAM1. Series of oxic and anoxic cultures of strain JAM1 were performed with N 2 O, [Formula: see text] or sodium nitroprusside, and growth and N 2 O, [Formula: see text], [Formula: see text] and N 2 concentrations were measured. Ammonium ([Formula: see text])-free cultures were also tested to assess the dynamics of N 2 O, [Formula: see text] and [Formula: see text]. Isotopic labeling of N 2 O was performed in 15 NH 4 + -amended cultures. Cultures with the JAM1Δ narG1narG2 double mutant were performed to assess the involvement of the Nar systems on N 2 O production. Finally, RT-qPCR was used to measure the gene expression levels of the denitrification genes cytochrome bc -type nitric oxide reductase ( cnorB1 and cnorB2 ) and nitrous oxide reductase ( nosZ ), and also nnrS and norR that encode NO-sensitive regulators. Strain JAM1 can reduce NO to N 2 O and N 2 O to N 2 and can sustain growth under anoxic conditions by reducing N 2 O as the sole electron acceptor. Although strain JAM1 lacks a gene encoding a dissimilatory [Formula: see text] reductase, [Formula: see text]-amended cultures produce N 2 O, representing up to 6% of the N-input. [Formula: see text] was shown to be the key intermediate of this production process. Upregulation in the expression of c norB1 , cnorB2, nnrS and nor

Shell biofilm-associated nitrous oxide production in marine molluscs

DEFF Research Database (Denmark)

Heisterkamp, I.M.; Schramm, Andreas; Larsen, Lone Heimann

2013-01-01

Emission of the greenhouse gas nitrous oxide (N2O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces...... are important sites of N2O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2O emission. Nitrification and denitrification were equally important sources of N2O in shell biofilms as revealed by 15N-stable isotope...... mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2O production of the shell biofilm. This animal-induced stimulation...

Recovery trends in marine mammal populations.

Directory of Open Access Journals (Sweden)

Anna M Magera

Full Text Available Marine mammals have greatly benefitted from a shift from resource exploitation towards conservation. Often lauded as symbols of conservation success, some marine mammal populations have shown remarkable recoveries after severe depletions. Others have remained at low abundance levels, continued to decline, or become extinct or extirpated. Here we provide a quantitative assessment of (1 publicly available population-level abundance data for marine mammals worldwide, (2 abundance trends and recovery status, and (3 historic population decline and recent recovery. We compiled 182 population abundance time series for 47 species and identified major data gaps. In order to compare across the largest possible set of time series with varying data quality, quantity and frequency, we considered an increase in population abundance as evidence of recovery. Using robust log-linear regression over three generations, we were able to classify abundance trends for 92 spatially non-overlapping populations as Significantly Increasing (42%, Significantly Decreasing (10%, Non-Significant Change (28% and Unknown (20%. Our results were comparable to IUCN classifications for equivalent species. Among different groupings, pinnipeds and other marine mammals (sirenians, polar bears and otters showed the highest proportion of recovering populations, likely benefiting from relatively fast life histories and nearshore habitats that provided visibility and protective management measures. Recovery was less frequent among cetaceans, but more common in coastal than offshore populations. For marine mammals with available historical abundance estimates (n = 47, larger historical population declines were associated with low or variable recent recoveries so far. Overall, our results show that many formerly depleted marine mammal populations are recovering. However, data-deficient populations and those with decreasing and non-significant trends require attention. In particular

Marine Microorganisms as Source of Stereoselective Esterases and Ketoreductases: Kinetic Resolution of a Prostaglandin Intermediate

KAUST Repository

De Vitis, Valerio; Guidi, Benedetta; Contente, Martina Letizia; Granato, Tiziana Mariarita; Conti, Paola; Molinari, Francesco; Crotti, Elena; Mapelli, Francesca; Borin, Sara S.; Daffonchio, Daniele; Romano, Diego

2014-01-01

A screening among bacterial strains isolated from water-brine interface of the deep hypersaline anoxic basins (DHABs) of the Eastern Mediterranean was carried out for the biocatalytical resolution of racemic propyl ester of anti-2-oxotricyclo[2.2.1.0]heptan-7-carboxylic acid (R,S)-1, a key intermediate for the synthesis of d-cloprostenol. Bacillus horneckiae 15A gave highly stereoselective reduction of (R,S)-1, whereas Halomonas aquamarina 9B enantioselectively hydrolysed (R,S)-1; in both cases, enantiomerically pure unreacted (R)-1 could be easily recovered and purified at molar conversion below 57–58 %, showing the potential of DHAB extremophile microbiome and marine-derived enzymes in stereoselective biocatalysis.

Marine Microorganisms as Source of Stereoselective Esterases and Ketoreductases: Kinetic Resolution of a Prostaglandin Intermediate

KAUST Repository

De Vitis, Valerio

2014-09-30

A screening among bacterial strains isolated from water-brine interface of the deep hypersaline anoxic basins (DHABs) of the Eastern Mediterranean was carried out for the biocatalytical resolution of racemic propyl ester of anti-2-oxotricyclo[2.2.1.0]heptan-7-carboxylic acid (R,S)-1, a key intermediate for the synthesis of d-cloprostenol. Bacillus horneckiae 15A gave highly stereoselective reduction of (R,S)-1, whereas Halomonas aquamarina 9B enantioselectively hydrolysed (R,S)-1; in both cases, enantiomerically pure unreacted (R)-1 could be easily recovered and purified at molar conversion below 57–58 %, showing the potential of DHAB extremophile microbiome and marine-derived enzymes in stereoselective biocatalysis.

Archaeal and bacterial communities respond differently to environmental gradients in anoxic sediments of a California hypersaline lake, the Salton Sea.

Science.gov (United States)

Swan, Brandon K; Ehrhardt, Christopher J; Reifel, Kristen M; Moreno, Lilliana I; Valentine, David L

2010-02-01

Sulfidic, anoxic sediments of the moderately hypersaline Salton Sea contain gradients in salinity and carbon that potentially structure the sedimentary microbial community. We investigated the abundance, community structure, and diversity of Bacteria and Archaea along these gradients to further distinguish the ecologies of these domains outside their established physiological range. Quantitative PCR was used to enumerate 16S rRNA gene abundances of Bacteria, Archaea, and Crenarchaeota. Community structure and diversity were evaluated by terminal restriction fragment length polymorphism (T-RFLP), quantitative analysis of gene (16S rRNA) frequencies of dominant microorganisms, and cloning and sequencing of 16S rRNA. Archaea were numerically dominant at all depths and exhibited a lesser response to environmental gradients than that of Bacteria. The relative abundance of Crenarchaeota was low (0.4 to 22%) at all depths but increased with decreased carbon content and increased salinity. Salinity structured the bacterial community but exerted no significant control on archaeal community structure, which was weakly correlated with total carbon. Partial sequencing of archaeal 16S rRNA genes retrieved from three sediment depths revealed diverse communities of Euryarchaeota and Crenarchaeota, many of which were affiliated with groups previously described from marine sediments. The abundance of these groups across all depths suggests that many putative marine archaeal groups can tolerate elevated salinity (5.0 to 11.8% [wt/vol]) and persist under the anaerobic conditions present in Salton Sea sediments. The differential response of archaeal and bacterial communities to salinity and carbon patterns is consistent with the hypothesis that adaptations to energy stress and availability distinguish the ecologies of these domains.

Microbial Diversity and Ecology in the Interfaces of the Deep-sea Anoxic Brine Pools in the Red Sea

KAUST Repository

Hikmawan, Tyas I.

2015-05-01

Deep-sea anoxic brine pools are one of the most extreme ecosystems on Earth, which are characterized by drastic changes in salinity, temperature, and oxygen concentration. The interface between the brine and overlaying seawater represents a boundary of oxic-anoxic layer and a steep gradient of redox potential that would initiate favorable conditions for divergent metabolic activities, mainly methanogenesis and sulfate reduction. This study aimed to investigate the diversity of Bacteria, particularly sulfate-reducing communities, and their ecological roles in the interfaces of five geochemically distinct brine pools in the Red Sea. Performing a comprehensive study would enable us to understand the significant role of the microbial groups in local geochemical cycles. Therefore, we combined culture-dependent approach and molecular methods, such as 454 pyrosequencing of 16S rRNA gene, phylogenetic analysis of functional marker gene encoding for the alpha subunits of dissimilatory sulfite reductase (dsrA), and single-cell genomic analysis to address these issues. Community analysis based on 16S rRNA gene sequences demonstrated high bacterial diversity and domination of Bacteria over Archaea in most locations. In the hot and multilayered Atlantis II Deep, the bacterial communities were stratified and hardly overlapped. Meanwhile in the colder brine pools, sulfatereducing Deltaproteobacteria were the most prominent bacterial groups inhabiting the interfaces. Corresponding to the bacterial community profile, the analysis of dsrA gene sequences revealed collectively high diversity of sulfate-reducing communities. Desulfatiglans-like dsrA was the prevalent group and conserved across the Red Sea brine pools. In addition to the molecular studies, more than thirty bacterial strains were successfully isolated and remarkably were found to be cytotoxic against the cancer cell lines. However, none of them were sulfate reducers. Thus, a single-cell genomic analysis was used to study

Loy Yang A - Australia's largest privatisation

International Nuclear Information System (INIS)

Yenckin, C.

1997-01-01

The recent A$4,746 million privatisation of the 2000MW Loy Yang A power station and the Loy Yang coal mine by the Victorian Government is Australia's largest privatisation and one of 1997's largest project financing deals. (author)

Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments.

Science.gov (United States)

Nauendorf, Alice; Krause, Stefan; Bigalke, Nikolaus K; Gorb, Elena V; Gorb, Stanislav N; Haeckel, Matthias; Wahl, Martin; Treude, Tina

2016-02-15

To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material. Copyright © 2016 Elsevier Ltd. All rights reserved.

Factors affecting virus dynamics and microbial host-virus interactions in marine environments

NARCIS (Netherlands)

Mojica, K.D.A.; Brussaard, C.P.D.

2014-01-01

Marine microorganisms constitute the largest percentage of living biomass and serve as the major driving force behind nutrient and energy cycles. While viruses only comprise a small percentage of this biomass (i.e., 5%), they dominate in numerical abundance and genetic diversity. Through host

Carbon-14 speciation during anoxic corrosion of activated steel in a repository environment

Energy Technology Data Exchange (ETDEWEB)

Wieland, E.; Cvetkovic, B.Z.; Kunz, D. [Paul Scherrer Institute, Villigen (Switzerland). Lab. for Waste Management; Salazar, G.; Szidat, S. [Bern Univ. (Switzerland). Dept. of Chemistry and Biochemistry and Oeschger Centre for Climate Change Research

2018-01-15

Radioactive waste contains significant amounts of {sup 14}C which has been identified a key radionuclide in safety assessments. In Switzerland, the {sup 14}C inventory of a cement-based repository for low- and intermediate-level radioactive waste (L/ILW) is mainly associated with activated steel (∝85 %). {sup 14}C is produced by {sup 14}N activation in steel parts exposed to thermal neutron flux in light water reactors. Release of {sup 14}C occurs in the near field of a deep geological repository due to anoxic corrosion of activated steel. Although the {sup 14}C inventory of the L/ILW repository and the sources of {sup 14}C are well known, the formation of {sup 14}C species during steel corrosion is only poorly understood. The aim of the present study was to identify and quantify the {sup 14}C-bearing carbon species formed during the anoxic corrosion of iron and steel and further to determine the {sup 14}C speciation in a corrosion experiment with activated steel. All experiments were conducted in conditions similar to those anticipated in the near field of a cement-based repository.

Food deprivation and prior anoxic coma have opposite effects on the activity of a visual interneuron in the locust.

Science.gov (United States)

Cross, Kevin P; Britton, Samantha; Mangulins, Rebecca; Money, Tomas G A; Robertson, R Meldrum

2017-04-01

We compared how different metabolic stressors, anoxic coma and food deprivation, affected signaling in neural tissue. We used the locust's Descending Contralateral Movement Detector (DCMD) interneuron because its large axon, high firing frequencies, and rapid conduction velocity make it energetically expensive. We exposed locusts to a 30min anoxic coma or 1day of food deprivation and found contrasting effects on signaling within the axon. After a prior anoxic coma, the DCMD fired fewer high-frequency (>200Hz) action potentials (APs) (Control: 12.4±1.6; Coma: 6.3±0.9) with a reduction in axonal conduction velocity (CV) at all frequencies (∼4-8%) when presented with a standard looming visual stimulus. Prior anoxic coma was also associated with a loss of supernormal conduction by reducing both the number of supernormal APs and the firing frequency with the highest CV. Initially, food deprivation caused a significant increase in the number of low- and high-frequency APs with no differences observed in CV. After controlling for isolation, food deprivation resulted in an increase in high-frequency APs (>200Hz: Control: 17.1±1.7; Food-deprived: 19.9±1.3) and an increase in relative conduction velocity for frequencies >150Hz (∼2%). Action potentials of food-deprived animals had a smaller half-width (Control: 0.45±0.02ms; Food-deprived: 0.40±0.01ms) and decay time (Control: 0.62±0.03ms; Food-deprived: 0.54±0.02ms). Our data indicate that the effects of metabolic stress on neural signaling can be stressor-dependent. Copyright © 2017 Elsevier Ltd. All rights reserved.

Define of internal recirculation coefficient for biological wastewater treatment in anoxic and aerobic bioreactors

Science.gov (United States)

Rossinskyi, Volodymyr

2018-02-01

The biological wastewater treatment technologies in anoxic and aerobic bioreactors with recycle of sludge mixture are used for the effective removal of organic compounds from wastewater. The change rate of sludge mixture recirculation between bioreactors leads to a change and redistribution of concentrations of organic compounds in sludge mixture in bioreactors and change hydrodynamic regimes in bioreactors. Determination of the coefficient of internal recirculation of sludge mixture between bioreactors is important for the choice of technological parameters of biological treatment (wastewater treatment duration in anoxic and aerobic bioreactors, flow capacity of recirculation pumps). Determination of the coefficient of internal recirculation of sludge mixture requires integrated consideration of hydrodynamic parameter (flow rate), kinetic parameter (rate of oxidation of organic compounds) and physical-chemical parameter of wastewater (concentration of organic compounds). The conducted numerical experiment from the proposed mathematical equations allowed to obtain analytical dependences of the coefficient of internal recirculation sludge mixture between bioreactors on the concentration of organic compounds in wastewater, the duration of wastewater treatment in bioreactors.

16S rRNA gene-based molecular analysis of mat-forming and accompanying bacteria covering organically-enriched marine sediments underlying a salmon farm in Southern Chile (Calbuco Island)

OpenAIRE

Aranda, Carlos; Paredes, Javier; Valenzuela, Cristian; Lam, Phyllis; Guillou, Laure

2010-01-01

The mat forming bacteria covering organic matter-enriched and anoxic marine sediments underlying a salmon farm in Southern Chile, were examined using 16S rRNA gene phylogenies. This mat was absent in the sea bed outside the direct influence of the farm (360 m outside fish cages). Based on nearly complete 16S rRNA gene sequences (-1500 bp), mat-forming filamentous cells were settled as the sulphur-oxidizing and putatively dissimilative nitrate-reducing Beggiatoa spp., being closely related (up...

Novel Pelagic Iron-Oxidizing Zetaproteobacteria from the Chesapeake Bay Oxic–Anoxic Transition Zone

Science.gov (United States)

Chiu, Beverly K.; Kato, Shingo; McAllister, Sean M.; Field, Erin K.; Chan, Clara S.

2017-01-01

Chemolithotrophic iron-oxidizing bacteria (FeOB) could theoretically inhabit any environment where Fe(II) and O2 (or nitrate) coexist. Until recently, marine Fe-oxidizing Zetaproteobacteria had primarily been observed in benthic and subsurface settings, but not redox-stratified water columns. This may be due to the challenges that a pelagic lifestyle would pose for Zetaproteobacteria, given low Fe(II) concentrations in modern marine waters and the possibility that Fe oxyhydroxide biominerals could cause cells to sink. However, we recently cultivated Zetaproteobacteria from the Chesapeake Bay oxic–anoxic transition zone, suggesting that they can survive and contribute to biogeochemical cycling in a stratified estuary. Here we describe the isolation, characterization, and genomes of two new species, Mariprofundus aestuarium CP-5 and Mariprofundus ferrinatatus CP-8, which are the first Zetaproteobacteria isolates from a pelagic environment. We looked for adaptations enabling strains CP-5 and CP-8 to overcome the challenges of living in a low Fe redoxcline with frequent O2 fluctuations due to tidal mixing. We found that the CP strains produce distinctive dreadlock-like Fe oxyhydroxide structures that are easily shed, which would help cells maintain suspension in the water column. These oxides are by-products of Fe(II) oxidation, likely catalyzed by the putative Fe(II) oxidase encoded by the cyc2 gene, present in both CP-5 and CP-8 genomes; the consistent presence of cyc2 in all microaerophilic FeOB and other FeOB genomes supports its putative role in Fe(II) oxidation. The CP strains also have two gene clusters associated with biofilm formation (Wsp system and the Widespread Colonization Island) that are absent or rare in other Zetaproteobacteria. We propose that biofilm formation enables the CP strains to attach to FeS particles and form flocs, an advantageous strategy for scavenging Fe(II) and developing low [O2] microenvironments within more oxygenated waters

Conspicuous veils formed by vibrioid bacteria on sulfidic marine sediment

DEFF Research Database (Denmark)

Thar, Roland Matthias; Kühl, Michael

2002-01-01

, but the bacteria have so far not been isolated in pure culture, and a detailed characterization of their metabolism is still lacking. The bacteria are colorless, gram-negative, and vibrioid-shaped (1.3- to 2.5- by 4- to 10-µm) cells that multiply by binary division and contain several spherical inclusions of poly......We describe the morphology and behavior of a hitherto unknown bacterial species that forms conspicuous veils (typical dimensions, 30 by 30 mm) on sulfidic marine sediment. The new bacteria were enriched on complex sulfidic medium within a benthic gradient chamber in oxygen-sulfide countergradients......, forming a cohesive whitish veil at the oxic-anoxic interface. Bacteria attached to the veil kept rotating and adapted their stalk lengths dynamically to changing oxygen concentrations. The joint action of rotating bacteria on the veil induced a homogeneous water flow from the oxic water region toward...

Marine mimivirus relatives are probably large algal viruses

Directory of Open Access Journals (Sweden)

Claverie Jean-Michel

2008-01-01

Full Text Available Abstract Background Acanthamoeba polyphaga mimivirus is the largest known ds-DNA virus and its 1.2 Mb-genome sequence has revealed many unique features. Mimivirus occupies an independent lineage among eukaryotic viruses and its known hosts include only species from the Acanthamoeba genus. The existence of mimivirus relatives was first suggested by the analysis of the Sargasso Sea metagenomic data. Results We now further demonstrate the presence of numerous "mimivirus-like" sequences using a larger marine metagenomic data set. We also show that the DNA polymerase sequences from three algal viruses (CeV01, PpV01, PoV01 infecting different marine algal species (Chrysochromulina ericina, Phaeocystis pouchetii, Pyramimonas orientalis are very closely related to their homolog in mimivirus. Conclusion Our results suggest that the numerous mimivirus-related sequences identified in marine environments are likely to originate from diverse large DNA viruses infecting phytoplankton. Micro-algae thus constitute a new category of potential hosts in which to look for new species of Mimiviridae.

Snellius II as a policy instrument for marine capacity building

NARCIS (Netherlands)

Stel, J.H.

2001-01-01

Indonesia is the largest archipelago in the world (1.8 million km2 of land, 3.1 million km2 of sea, plus a 200 miles Exclusive Economic Zone covering some 2.7 million km2). Its population, ranking number four on the world list, amounts to more than 216 million people. Marine related programmes are

Microscopic and Spectroscopic Characterisation of Waterlogged Archaeological Softwood from Anoxic Environments

DEFF Research Database (Denmark)

Pedersen, Nanna Bjerregaard

waterlogged sites and solely decayed by erosion bacteria to refine the understanding of the residual wood structure left after degradation. This was done not only to improve the ability to develop suitable and cost effective conservations treatments but also to improve the understanding of anaerobic decay...... mechanisms acting on plant biomass in waterlogged anoxic environment.Morphological analyses showed typical erosion bacteria decay patterns in the residual wood structure. Decay resistance of some cell types and cell wall compartments in preference to others is most likely explained not only by elevated...

Organic carbon degradation in arctic marine sediments, Svalbard: A comparison of initial and terminal steps

DEFF Research Database (Denmark)

Arnosti, C.; Jørgensen, BB

2006-01-01

carbohydrate concentrations were comparable to those measured in more temperate sediments, and likely comprise a considerable fraction of porewater dissolved organic carbon. A comparison of dissolved carbohydrate inventories with hydrolysis and sulfate reduction rates suggests that the turnover of carbon......Degradation of marine organic matter under anoxic conditions involves microbial communities working in concert to remineralize complex substrates to CO2. In order to investigate the coupling between the initial and terminal steps of this sequence in permanently cold sediments, rates...... of extracellular enzymatic hydrolysis and sulfate reduction were measured in parallel cores collected from 5 fjords on the west and northwest coast of Svalbard, in the high Arctic. Inventories of total dissolved carbohydrates were also measured in order to evaluate their potential role in carbon turnover...

Denitrifying metabolism of the methylotrophic marine bacterium Methylophaga nitratireducenticrescens strain JAM1

Directory of Open Access Journals (Sweden)

Florian Mauffrey

2017-11-01

Full Text Available Background Methylophaga nitratireducenticrescens strain JAM1 is a methylotrophic, marine bacterium that was isolated from a denitrification reactor treating a closed-circuit seawater aquarium. It can sustain growth under anoxic conditions by reducing nitrate ( ${\\mathrm{NO}}_{3}^{-}$ NO 3 − to nitrite ( ${\\mathrm{NO}}_{2}^{-}$ NO 2 − . These physiological traits are attributed to gene clusters that encode two dissimilatory nitrate reductases (Nar. Strain JAM1 also contains gene clusters encoding two nitric oxide (NO reductases and one nitrous oxide (N2O reductase, suggesting that NO and N2O can be reduced by strain JAM1. Here we characterized further the denitrifying activities of M. nitratireducenticrescens JAM1. Methods Series of oxic and anoxic cultures of strain JAM1 were performed with N2O, ${\\mathrm{NO}}_{3}^{-}$ NO 3 − or sodium nitroprusside, and growth and N2O, ${\\mathrm{NO}}_{3}^{-}$ NO 3 − , ${\\mathrm{NO}}_{2}^{-}$ NO 2 − and N2 concentrations were measured. Ammonium ( ${\\mathrm{NH}}_{4}^{+}$ NH 4 + -free cultures were also tested to assess the dynamics of N2O, ${\\mathrm{NO}}_{3}^{-}$ NO 3 − and ${\\mathrm{NO}}_{2}^{-}$ NO 2 − . Isotopic labeling of N2O was performed in 15NH4+-amended cultures. Cultures with the JAM1ΔnarG1narG2 double mutant were performed to assess the involvement of the Nar systems on N2O production. Finally, RT-qPCR was used to measure the gene expression levels of the denitrification genes cytochrome bc-type nitric oxide reductase (cnorB1 and cnorB2 and nitrous oxide reductase (nosZ, and also nnrS and norR that encode NO-sensitive regulators. Results Strain JAM1 can reduce NO to N2O and N2O to N2 and can sustain growth under anoxic conditions by reducing N2O as the sole electron acceptor. Although strain JAM1 lacks a gene encoding a dissimilatory ${\\mathrm{NO}}_{2}^{-}$ NO 2 − reductase, ${\\mathrm{NO}}_{3}^{-}$ NO 3 − -amended cultures produce N2O, representing up to 6% of the N

Hydrolysis and degradation of filtrated organic particulates in a biofilm reactor under anoxic and aerobic conditions

DEFF Research Database (Denmark)

Janning, K.F.; Mesterton, K.; Harremoës, P.

1997-01-01

Two experiments were performed in order to investigate the anoxic and the aerobic degradation of filtrated organic matter in a biofilter. In submerged lab: scale reactors with Biocarbone media as filter material, accumulated particulate organic matter from pre-settled wastewater served as the only...

Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

NARCIS (Netherlands)

Beyer, F.; Rietman, B.M.; Zwijnenburg, A.; Brink, van den P.; Vrouwenvelder, J.S.; Jarzembowska, M.; Laurinonyte, J.; Stams, A.J.M.; Plugge, C.M.

2014-01-01

Long-term performance and fouling behavior of four full-scale nanofiltration (NF) plants, treating anoxic groundwater at 80% recovery for drinking water production, were characterized and compared with oxic NF and reverse osmosis systems. Plant operating times varied between 6 and 10 years and

Marine renewable energy legislation for Nova Scotia : policy background paper

International Nuclear Information System (INIS)

2010-07-01

Marine renewable energy sources can provide Nova Scotia with a large supply of sustainable, non-carbon emitting electricity. One of the largest tidal ranges within the world is contained within the Bay of Fundy, which holds power potential in the form of wind, wave and tidal energy. A strategic environmental assessment (SEA) on the Bay of Fundy's potential marine renewable energy was published in 2008. An assessment of the social, economic, and environmental effects and factors linked with possible development of renewable energy sources in the Bay Fundy was published. Twenty-nine recommendations were offered, including the creation of marine renewable energy legislation incorporating sustainability principles. This discussion paper described the policy drivers and opportunities in Nova Scotia for marine renewable energy sources as well as the challenges and relevant subject areas that should be considered when creating marine renewable energy legislation and policy. Specific challenges that were discussed included a policy approach to development; multiple jurisdictions; Aboriginal issues; economic factors; environmental impacts; occupational and operation safety; allocation of rights; and regulatory issues. It was concluded that if the marine renewable energy resource was going to be created with the possibility of providing commercial electricity generation, a coordinated legislative framework should be established. refs., tabs.

Exopolysaccharides from Marine and Marine Extremophilic Bacteria: Structures, Properties, Ecological Roles and Applications

Directory of Open Access Journals (Sweden)

Angela Casillo

2018-02-01

Full Text Available The marine environment is the largest aquatic ecosystem on Earth and it harbours microorganisms responsible for more than 50% of total biomass of prokaryotes in the world. All these microorganisms produce extracellular polymers that constitute a substantial part of the dissolved organic carbon, often in the form of exopolysaccharides (EPS. In addition, the production of these polymers is often correlated to the establishment of the biofilm growth mode, during which they are important matrix components. Their functions include adhesion and colonization of surfaces, protection of the bacterial cells and support for biochemical interactions between the bacteria and the surrounding environment. The aim of this review is to present a summary of the status of the research about the structures of exopolysaccharides from marine bacteria, including capsular, medium released and biofilm embedded polysaccharides. Moreover, ecological roles of these polymers, especially for those isolated from extreme ecological niches (deep-sea hydrothermal vents, polar regions, hypersaline ponds, etc., are reported. Finally, relationships between the structure and the function of the exopolysaccharides are discussed.

Hyperbaric oxygen sensitizes anoxic Pseudomonas aeruginosa biofilm to ciprofloxacin

DEFF Research Database (Denmark)

Kolpen, Mette; Lerche, Christian J; Kragh, Kasper Nørskov

2017-01-01

Chronic Pseudomonas aeruginosa lung infection is characterized by the presence of endobronchial antibiotic-tolerant biofilm subject to strong oxygen (O2) depletion due to the activity of surrounding polymorphonuclear leukocytes. The exact mechanisms affecting the antibiotic susceptibility...... metabolism activity and the endogenous formation of reactive O2 radicals (ROS). In this study we aimed to apply hyperbaric oxygen treatment (HBOT) in order to sensitize anoxic P. aeruginosa agarose-biofilms established to mimic situations with intense O2 consumption by the host response in the cystic...... fibrosis (CF) lung. Application of HBOT resulted in enhanced bactericidal activity of ciprofloxacin at clinically relevant durations and was accompanied by indications of restored aerobic respiration, involvement of endogenous lethal oxidative stress and increased bacterial growth. The findings highlight...

The marine ecosystems at Forsmark and Laxemar-Simpevarp. SR-Site Biosphere

Energy Technology Data Exchange (ETDEWEB)

Aquilonius, Karin [ed.; Studsvik Nuclear AB (Sweden)

2010-12-15

mean for the Baltic Sea and slightly lower in Laxemar-Simpevarp. The sea level at Forsmark has since 2003 fluctuated between 0.6 m below and 1.3 m above the mean level, and the corresponding values for Laxemar-Simpevarp are 0.5 and 0.7 m. Due to the gentler slope of the coastline, the sea level fluctuations have a more marked effect in Forsmark, than in the Laxemar-Simpevarp landscape, exhibiting a steeper slope. In Forsmark the macrophyte vegetation in the photic zone is dominated by red algae and brown filamentous algae. In Laxemar-Simpevarp, the red algae community covers the largest area. The benthic biomass at the bottom sampling sites in Forsmark has been dominated by the Baltic mussel. In Laxemar-Simpevarp the sessile macro fauna attached to hard substrates is completely dominated by the blue mussel in terms of both biomass and abundance. Test fishing in Forsmark and Laxemar-Simpevarp show similar development as in other nearby coastal areas and herring and sprat are the dominant species in offshore areas at both sites. In the inner bays at the sites, perch and pike are the most frequent species. The biomass in Forsmark is dominated by the primary producers and is focused along the shoreline of the area. On average, the marine area in Forsmark shows a positive Net Ecosystem Production (NEP), although most of the area is heterotrophic. The coastal shallow basins tend to be autotrophic, whereas the more offshore basins are heterothropic. The largest carbon pool in all basins in Forsmark is the abiotic pools (i.e. sediment, DIC and DOC) followed by the macrophytes. The major carbon flux in the ecosystem is the advective flux caused by the movement of sea water. All biotic fluxes are small in comparison with the advective flux. The largest biotic flux is fixation of carbon by primary producers. On average 4% of the initially consumed carbon in the marine ecosystem food web is transferred to the top predators. For nitrogen, phosphorus and thorium, the major pool in

The marine ecosystems at Forsmark and Laxemar-Simpevarp. SR-Site Biosphere

International Nuclear Information System (INIS)

Aquilonius, Karin

2010-12-01

mean for the Baltic Sea and slightly lower in Laxemar-Simpevarp. The sea level at Forsmark has since 2003 fluctuated between 0.6 m below and 1.3 m above the mean level, and the corresponding values for Laxemar-Simpevarp are 0.5 and 0.7 m. Due to the gentler slope of the coastline, the sea level fluctuations have a more marked effect in Forsmark, than in the Laxemar-Simpevarp landscape, exhibiting a steeper slope. In Forsmark the macrophyte vegetation in the photic zone is dominated by red algae and brown filamentous algae. In Laxemar-Simpevarp, the red algae community covers the largest area. The benthic biomass at the bottom sampling sites in Forsmark has been dominated by the Baltic mussel. In Laxemar-Simpevarp the sessile macro fauna attached to hard substrates is completely dominated by the blue mussel in terms of both biomass and abundance. Test fishing in Forsmark and Laxemar-Simpevarp show similar development as in other nearby coastal areas and herring and sprat are the dominant species in offshore areas at both sites. In the inner bays at the sites, perch and pike are the most frequent species. The biomass in Forsmark is dominated by the primary producers and is focused along the shoreline of the area. On average, the marine area in Forsmark shows a positive Net Ecosystem Production (NEP), although most of the area is heterotrophic. The coastal shallow basins tend to be autotrophic, whereas the more offshore basins are heterothropic. The largest carbon pool in all basins in Forsmark is the abiotic pools (i.e. sediment, DIC and DOC) followed by the macrophytes. The major carbon flux in the ecosystem is the advective flux caused by the movement of sea water. All biotic fluxes are small in comparison with the advective flux. The largest biotic flux is fixation of carbon by primary producers. On average 4% of the initially consumed carbon in the marine ecosystem food web is transferred to the top predators. For nitrogen, phosphorus and thorium, the major pool in

Diversity of methanogens and sulfate-reducing bacteria in the interfaces of five deep-sea anoxic brines of the Red Sea

KAUST Repository

Guan, Yue

2015-11-01

Oceanic deep hypersaline anoxic basins (DHABs) are characterized by drastic changes in physico-chemical conditions in the transition from overlaying seawater to brine body. Brine-seawater interfaces (BSIs) of several DHABs across the Mediterranean Sea have been shown to possess methanogenic and sulfate-reducing activities, yet no systematic studies have been conducted to address the potential functional diversity of methanogenic and sulfate-reducing communities in the Red Sea DHABs. Here, we evaluated the relative abundance of Bacteria and Archaea using quantitative PCR and conducted phylogenetic analyses of nearly full-length 16S rRNA genes as well as functional marker genes encoding the alpha subunits of methyl-coenzyme M reductase (mcrA) and dissimilatory sulfite reductase (dsrA). Bacteria predominated over Archaea in most locations, the majority of which were affiliated with Deltaproteobacteria, while Thaumarchaeota were the most prevalent Archaea in all sampled locations. The upper convective layers of Atlantis II Deep, which bear increasingly harsh environmental conditions, were dominated by members of the class Thermoplasmata (Marine Benthic Group E and Mediterranean Sea Brine Lakes Group 1). Our study revealed unique microbial compositions, the presence of niche-specific groups, and collectively, a higher diversity of sulfate-reducing communities compared to methanogenic communities in all five studied locations. © 2015 Institut Pasteur.

Diversity of methanogens and sulfate-reducing bacteria in the interfaces of five deep-sea anoxic brines of the Red Sea

KAUST Repository

Guan, Yue; Hikmawan, Tyas; Antunes, Andre; Ngugi, David; Stingl, Ulrich

2015-01-01

Oceanic deep hypersaline anoxic basins (DHABs) are characterized by drastic changes in physico-chemical conditions in the transition from overlaying seawater to brine body. Brine-seawater interfaces (BSIs) of several DHABs across the Mediterranean Sea have been shown to possess methanogenic and sulfate-reducing activities, yet no systematic studies have been conducted to address the potential functional diversity of methanogenic and sulfate-reducing communities in the Red Sea DHABs. Here, we evaluated the relative abundance of Bacteria and Archaea using quantitative PCR and conducted phylogenetic analyses of nearly full-length 16S rRNA genes as well as functional marker genes encoding the alpha subunits of methyl-coenzyme M reductase (mcrA) and dissimilatory sulfite reductase (dsrA). Bacteria predominated over Archaea in most locations, the majority of which were affiliated with Deltaproteobacteria, while Thaumarchaeota were the most prevalent Archaea in all sampled locations. The upper convective layers of Atlantis II Deep, which bear increasingly harsh environmental conditions, were dominated by members of the class Thermoplasmata (Marine Benthic Group E and Mediterranean Sea Brine Lakes Group 1). Our study revealed unique microbial compositions, the presence of niche-specific groups, and collectively, a higher diversity of sulfate-reducing communities compared to methanogenic communities in all five studied locations. © 2015 Institut Pasteur.

The upper to uppermost Cenomanian oceanic anoxic event: a review and an interpretation involving a seawater stratification by the CO{sub 2} of mantle origin; L`evenement oceanique anoxique du Cenomanien superieur-terminal: une revue et une interpretation mettant en jeu une stratification des eaux marines par le CO{sub 2} mantellique

Energy Technology Data Exchange (ETDEWEB)

Busson, G; Cornee, A [Laboratoire de Geologie du Museum, 75 - Paris (France)

1997-12-31

Oil exploration data have revealed the exceptional richness of the middle Cretaceous in source rocks worldwide. Oceanic drillings have shown the existence of oceanic anoxic events (OAE) well defined in time. This study analyzes the OAE 2 event dated from the upper Cenomanian-lower Turonian. This event has been recognized in numerous sites from the northern, central and southern Atlantic and punctually in the Pacific and Indian oceans. It occurs in both numerous deep oceanic sites and orogenic zones, and stable platforms covered by epeiric seas. It coincides with a sea level rise which is one of the most sudden and highest in Phanerozoic times and it stands out as a remarkable episode of massive faunal extinction which led to the deposition of organic matter of marine planktonic dominant nature. The first part of the study recalls the previous interpretations of this event (oceanic stratification, euxinic conditions, spreading of an oxygen minimum zone, greenhouse climate effect, sluggish atmospheric and oceanic circulations, high planktonic production, great oceanic overturns, marginal or general upwellings, marine transgressions on epeiric areas etc..). The second part gives the basis of the new hypothesis: connection between separated seas due to the transgression, retreat of evaporite facies, high sea-floor spreading rates, intense volcanic activity and high mantle outgassing with huge CO{sub 2} influxes. The last part describes the proposed interpretation: CO{sub 2} accumulation in deep and intermediate waters and sea overflows on marginal and continental areas which led to a rise of the CO{sub 2}-rich hypolimnion. (J.S.) 236 refs.

The upper to uppermost Cenomanian oceanic anoxic event: a review and an interpretation involving a seawater stratification by the CO{sub 2} of mantle origin; L`evenement oceanique anoxique du Cenomanien superieur-terminal: une revue et une interpretation mettant en jeu une stratification des eaux marines par le CO{sub 2} mantellique

Energy Technology Data Exchange (ETDEWEB)

Busson, G.; Cornee, A. [Laboratoire de Geologie du Museum, 75 - Paris (France)

1996-12-31

Oil exploration data have revealed the exceptional richness of the middle Cretaceous in source rocks worldwide. Oceanic drillings have shown the existence of oceanic anoxic events (OAE) well defined in time. This study analyzes the OAE 2 event dated from the upper Cenomanian-lower Turonian. This event has been recognized in numerous sites from the northern, central and southern Atlantic and punctually in the Pacific and Indian oceans. It occurs in both numerous deep oceanic sites and orogenic zones, and stable platforms covered by epeiric seas. It coincides with a sea level rise which is one of the most sudden and highest in Phanerozoic times and it stands out as a remarkable episode of massive faunal extinction which led to the deposition of organic matter of marine planktonic dominant nature. The first part of the study recalls the previous interpretations of this event (oceanic stratification, euxinic conditions, spreading of an oxygen minimum zone, greenhouse climate effect, sluggish atmospheric and oceanic circulations, high planktonic production, great oceanic overturns, marginal or general upwellings, marine transgressions on epeiric areas etc..). The second part gives the basis of the new hypothesis: connection between separated seas due to the transgression, retreat of evaporite facies, high sea-floor spreading rates, intense volcanic activity and high mantle outgassing with huge CO{sub 2} influxes. The last part describes the proposed interpretation: CO{sub 2} accumulation in deep and intermediate waters and sea overflows on marginal and continental areas which led to a rise of the CO{sub 2}-rich hypolimnion. (J.S.) 236 refs.

Factors involved in the (near) anoxic survival time of Cerastoderma edule: associated bacteria vs. endogenous fuel

NARCIS (Netherlands)

Babarro, J.M.F.; De Zwaan, A.

2001-01-01

The effect of several antibiotics, molybdate and hydrogen sulfide was tested on anoxic tolerance of the cockle Cerastoderma edule, as well as utilisation of glycogen. The aim was to evaluate the role of fuel depletion and growth of bacteria as a cause of mortality. The exponential increase of

Nursing management of reflex anoxic seizures in children.

Science.gov (United States)

Patel, Neal; Kerr-Liddell, Rowan; Challis, Louise; Paul, Siba Prosad

2017-04-13

Children who present with transient loss of consciousness (T-LOC) are often first seen in emergency departments (EDs). Reflex anoxic seizure (RAS), vasovagal syncope and prolonged respiratory apnoea are benign, syncopal events that can be generally managed by explanation and reassurance. RAS is a short, paroxysmal, self-reverting episode of asystole that is triggered by pain, fear or anxiety and is caused by increased vagal response. It is an important differential diagnosis in pre-school age children who present with T-LOC, but is often underdiagnosed and can sometimes be misdiagnosed as epilepsy. Nurses working in EDs are among the first healthcare professionals to see children in acute settings and should therefore be aware of RAS, the presenting features and management options. This article discusses the epidemiology, pathophysiology and management of RAS, includes an illustrative case study and discusses the role of ED nurses.

Translational regulation in the anoxic turtle, Trachemys scripta elegans.

Science.gov (United States)

Szereszewski, Kama E; Storey, Kenneth B

2017-12-14

The red-eared slider turtle (Trachemys scripta elegans), has developed remarkable adaptive mechanisms for coping with decreased oxygen availability during winter when lakes and ponds become covered with ice. Strategies for enduring anoxia tolerance include an increase in fermentable fuel reserves to support anaerobic glycolysis, the buffering of end products to minimize acidosis, altered expression in crucial survival genes, and strong metabolic rate suppression to minimize ATP-expensive metabolic processes such as protein synthesis. The mammalian target of rapamycin (mTOR) is at the center of the insulin-signaling pathway that regulates protein translation. The present study analyzed the responses of the mTOR signaling pathway to 5 (5H) or 20 h (20H) of anoxic submergence in liver and skeletal muscle of T. scripta elegans with a particular focus on regulatory changes in the phosphorylation states of targets. The data showed that phosphorylation of multiple mTOR targets was suppressed in skeletal muscle, but activated in the liver. Phosphorylated mTOR Ser2448 showed no change in skeletal muscle but had increased by approximately 4.5-fold in the liver after 20H of anoxia. The phosphorylation states of upstream positive regulators of mTOR (p-PDK-1 Ser241 , p-AKT Ser473 , and protein levels of GβL), the relative levels of dephosphorylated active PTEN, as well as phosphorylation state of negative regulators (TSC2 Thr1462 , p-PRAS40 Thr246 ) were generally found to be differentially regulated in skeletal muscle and in liver. Downstream targets of mTOR (p-p70 S6K Thr389 , p-S6 Ser235 , PABP, p-4E-BP1 Thr37/46 , and p-eIF4E Ser209 ) were generally unchanged in skeletal muscle but upregulated in most targets in liver. These findings indicate that protein synthesis is enhanced in the liver and suggests an increase in the synthesis of crucial proteins required for anoxic survival.

Speciation and Distribution of Trace Metals and Organic Matter in Marine Lake as In Situ Laboratory

Science.gov (United States)

Mlakar, M.; Fiket, Ž.; Cuculić, V.; Cukrov, N.; Geček, S.

2016-02-01

Marine lakes are unique, isolated marine systems, also recognized as in situ "laboratories" in which geochemical processes on a different scale compared to the open sea, can be observed. Impact of organic matter cycling on distribution of trace metals in the marine lake Mir, located on Dugi Otok Island, in the central part of the eastern Adriatic Sea, was investigated. Intense spatial and seasonal variations of physico-chemical parameters and organic matter concentrations in the water column of the Lake are governed predominantly by natural processes. Enhanced oxygen consumption in the Lake during summer season, high organic carbon concentrations and low redox potential result in occasional occurrence of anoxic conditions in the bottom layers. Speciation modelling showed that dissolved trace metals Cu, Pb and Zn, are mostly bound to organic matter, while Cd, Co and Ni are present predominantly as free ions and inorganic complexes. Trace metals removal from the water column and their retention in the sediment was found to depend on the nature of the relationship between specific metal and high proportion of organic matter (up to 9%) and inorganic phases, Fe-oxyhydroxydes or biogenic calcite. Surrounding karstic background, with occasional occurrences of red soil characterize deposited sediments as coarse grained and carbonate rich, whose elemental composition is affected by bathymetry of the basin and overall biological production.

Bruxism Associated with Anoxic Encephalopathy: Successful Treatment with Baclofen

Directory of Open Access Journals (Sweden)

A. Bruce Janati

2013-01-01

Full Text Available Introduction. Bruxism is a movement disorder characterized by grinding and clenching of the teeth. Etiology of bruxism can be divided into three groups: psychosocial factors, peripheral factors, and pathophysiological factors. Methods. The clinical investigation was conducted at King Khaled Hospital in Hail, Saudi Arabia, in 2012. Results. A 16-year-old Saudi female was brought to the hospital in a comatose state and with generalized convulsive seizures secondary to acute anoxic encephalopathy. In the third week of hospitalization, while still in a state of akinetic mutism, she developed incessant bruxism which responded favorably to a GABA receptor agonist (baclofen. Conclusion. Our data support the hypothesis that bruxism emanates from imbalance or dysregulation of the neurotransmitter system. Larger scale studies will be needed to confirm this hypothesis.

Arctic Ocean circulation during the anoxic Eocene Azolla event

Science.gov (United States)

Speelman, Eveline; Sinninghe Damsté, Jaap; März, Christian; Brumsack, Hans; Reichart, Gert-Jan

2010-05-01

The Azolla interval, as encountered in Eocene sediments from the Arctic Ocean, is characterized by organic rich sediments ( 4wt% Corg). In general, high levels of organic matter may be caused by increased productivity, i.e. extensive growth of Azolla, and/or enhanced preservation of organic matter, or a combination of both. Anoxic (bottom) water conditions, expanded oxygen minimum zones, or increased sedimentation rates all potentially increase organic matter preservation. According to plate tectonic, bathymetric, and paleogeographic reconstructions, the Arctic Ocean was a virtually isolated shallow basin, with one possible deeper connection to the Nordic Seas represented by a still shallow Fram Strait (Jakobsson et al., 2007), hampering ventilation of the Arctic Basin. During the Azolla interval surface waters freshened, while at the same time bottom waters appear to have remained saline, indicating that the Arctic was highly stratified. The restricted ventilation and stratification in concert with ongoing export of organic matter most likely resulted in the development of anoxic conditions in the lower part of the water column. Whereas the excess precipitation over evaporation maintained the freshwater lid, sustained input of Nordic Sea water is needed to keep the deeper waters saline. To which degree the Arctic Ocean exchanged with the Nordic Seas is, however, still largely unknown. Here we present a high-resolution trace metal record (ICP-MS and ICP-OES) for the expanded Early/Middle Eocene section capturing the Azolla interval from Integrated Ocean Drilling Program (IODP) Expedition 302 (ACEX) drilled on the Lomonosov Ridge, central Arctic Ocean. Euxinic conditions throughout the interval resulted in the efficient removal of redox sensitive trace metals from the water column. Using the sedimentary trace metal record we also constrained circulation in the Arctic Ocean by assessing the relative importance of trace metal input sources (i.e. fluvial, eolian, and

Triassic marine reptiles gave birth to live young.

Science.gov (United States)

Cheng, Yen-Nien; Wu, Xiao-Chun; Ji, Qiang

2004-11-18

Sauropterygians form the largest and most diverse group of ancient marine reptiles that lived throughout nearly the entire Mesozoic era (from 250 to 65 million years ago). Although thousands of specimens of this group have been collected around the world since the description of the first plesiosaur in 1821 (ref. 3), no direct evidence has been found to determine whether any sauropterygians came on shore to lay eggs (oviparity) like sea turtles, or gave birth in the water to live young (viviparity) as ichthyosaurs and mosasauroids (marine lizards) did. Viviparity has been proposed for plesiosaur, pachypleurosaur and nothosaur sauropterygians, but until now no concrete evidence has been advanced. Here we report two gravid specimens of Keichousaurus hui Young from the Middle Triassic of China. These exquisitely preserved specimens not only provide the first unequivocal evidence of reproductive mode and sexual dimorphism in sauropterygians, but also indicate that viviparity could have been expedited by the evolution of a movable pelvis in pachypleurosaurs. By extension, this has implications for the reproductive pattern of other sauropterygians and Mesozoic marine reptiles that possessed a movable pelvis.

Terrestrial P and Reactive N and Marine Productivity in the Late Devonian Appalachian Basin

Science.gov (United States)

Tuite, M. L.; Macko, S. A.

2009-12-01

A causal link between the Late Devonian emergence of forest ecosystems and episodic black shale deposition has been proposed by several authors. Most attribute increases in epicontinental basin productivity to elevated rates of terrestrial phosphorus weathering facilitated by the co-evolution of root systems and soils. Two reasons to suspect that an increase in the P weathering flux was not the primary cause of organic-rich shale deposition are as follows. First, most Late Devonian black shales were deposited during sea level transgressions, periods when riverine fluxes of sediment and mineral nutrients such as P to marine basins were diminished. Second, Late Devonian forests were restricted to warm, moist lowlands where P was sequestered in soils as inorganic, occluded forms. However, the export flux of reactive N from these forests to adjacent epeiric seas by riverine and atmospheric deposition was enhanced by the warm, wet climate and expanding areal extent of forests. Abundant terrestrial reactive N primed the marine eutrophication pump by extending the residence time of P in the photic zone, permitting extensive growth of primary biomass. The consequent flux of organic matter to the sea floor created anoxic bottom waters that, in turn, allowed for the remobilization of P into the water column. Based on abundance and isotopic analyses of organic and inorganic C, N, P, and S from terrestrial and marine environments within and adjacent to the Late Devonian Appalachian Basin, this latter scenario is supported.

Diffusive Gradients in Thin Films Reveals Differences in Antimony and Arsenic Mobility in a Contaminated Wetland Sediment during an Oxic-Anoxic Transition.

Science.gov (United States)

Arsic, Maja; Teasdale, Peter R; Welsh, David T; Johnston, Scott G; Burton, Edward D; Hockmann, Kerstin; Bennett, William W

2018-02-06

Antimony (Sb) and arsenic (As) are priority environmental contaminants that often co-occur at mining-impacted sites. Despite their chemical similarities, Sb mobility in waterlogged sediments is poorly understood in comparison to As, particularly across the sediment-water interface (SWI) where changes can occur at the millimeter scale. Combined diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques provided a high resolution, in situ comparison between Sb, As, and iron (Fe) speciation and mobility across the SWI in contaminated freshwater wetland sediment mesocosms under an oxic-anoxic-oxic transition. The shift to anoxic conditions released Fe(II), As(III), and As(V) from the sediment to the water column, consistent with As release being coupled to the reductive dissolution of iron(III) (hydr)oxides. Conversely, Sb(III) and Sb(V) effluxed to the water column under oxic conditions and fluxed into the sediment under anoxic conditions. Porewater DGT-DET depth profiles showed apparent decoupling between Fe(II) and Sb release, as Sb was primarily mobilized across the SWI under oxic conditions. Solid-phase X-ray absorption spectroscopy (XAS) revealed the presence of an Sb(III)-S phase in the sediment that increased in proportion with depth and the transition from oxic to anoxic conditions. The results of this study showed that Sb mobilization was decoupled from the Fe cycle and was, therefore, more likely linked to sulfur and/or organic carbon (e.g., most likely authigenic antimony sulfide formation or Sb(III) complexation by reduced organic sulfur functional groups).

Contaminants reduce the richness and evenness of marine communities: A review and meta-analysis

International Nuclear Information System (INIS)

Johnston, Emma L.; Roberts, David A.

2009-01-01

Biodiversity of marine ecosystems is integral to their stability and function and is threatened by anthropogenic processes. We conducted a literature review and meta-analysis of 216 studies to understand the effects of common contaminants upon diversity in various marine communities. The most common diversity measures were species richness, the Shannon-Wiener index (H') and Pielou evenness (J). Largest effect sizes were observed for species richness, which tended to be the most sensitive index. Pollution was associated with marine communities containing fewer species or taxa than their pristine counterparts. Marine habitats did not vary in their susceptibility to contamination, rather a ∼40% reduction in richness occurred across all habitats. No class of contaminant was associated with significantly greater impacts on diversity than any other. Survey studies identified larger effects than laboratory or field experiments. Anthropogenic contamination is strongly associated with reductions in the species richness and evenness of marine habitats. - Contamination substantially reduces the biodiversity of marine communities in all major habitat types and across all major contaminant classes.

Surviving in a marine desert: The sponge loop retains resources within coral reefs

NARCIS (Netherlands)

de Goeij, J.M.; van Oevelen, D.; Vermeij, M.J.A.; Osinga , R.; Middelburg, J.J.; de Goeij, A.F.P.M.; Admiraal, W.

2013-01-01

Ever since Darwin’s early descriptions of coral reefs, scientists have debated how one of the world’s most productive and diverse ecosystems can thrive in the marine equivalent of a desert. It is an enigma how the flux of dissolved organic matter (DOM), the largest resource produced on reefs, is

Surviving in a marine desert: the sponge loop retains resources within coral reefs

NARCIS (Netherlands)

de Goei, J.M.; van Oevelen, D.; Vermeij, M.J.A.; Osinga, R.; Middelburg, J.J.; de Goei, A.F.P.M.; Admiraal, W.

2013-01-01

Ever since Darwin’s early descriptions of coral reefs, scientists have debated how one of the world’s most productive and diverse ecosystems can thrive in the marine equivalent of a desert. It is an enigma how the flux of dissolved organic matter (DOM), the largest resource produced on reefs, is

Surviving in a Marine Desert: The Sponge Loop Retains Resources Within Coral Reefs

NARCIS (Netherlands)

de Goeij, J.M.; van Oevelen, D.; Vermeij, M.J.A.; Osinga, R.; Middelburg, J.J.; de Goeij, A.F.P.M.; Admiraal, W.

2013-01-01

Ever since Darwin’s early descriptions of coral reefs, scientists have debated how one of the world’s most productive and diverse ecosystems can thrive in the marine equivalent of a desert. It is an enigma how the flux of dissolved organic matter (DOM), the largest resource produced on reefs, is

Trimethylamine and trimethylamine N-oxide are supplementary energy sources for a marine heterotrophic bacterium: implications for marine carbon and nitrogen cycling.

Science.gov (United States)

Lidbury, Ian D E A; Murrell, J Colin; Chen, Yin

2015-03-01

Bacteria of the marine Roseobacter clade are characterised by their ability to utilise a wide range of organic and inorganic compounds to support growth. Trimethylamine (TMA) and trimethylamine N-oxide (TMAO) are methylated amines (MA) and form part of the dissolved organic nitrogen pool, the second largest source of nitrogen after N2 gas, in the oceans. We investigated if the marine heterotrophic bacterium, Ruegeria pomeroyi DSS-3, could utilise TMA and TMAO as a supplementary energy source and whether this trait had any beneficial effect on growth. In R. pomeroyi, catabolism of TMA and TMAO resulted in the production of intracellular ATP which in turn helped to enhance growth rate and growth yield as well as enhancing cell survival during prolonged energy starvation. Furthermore, the simultaneous use of two different exogenous energy sources led to a greater enhancement of chemoorganoheterotrophic growth. The use of TMA and TMAO primarily as an energy source resulted in the remineralisation of nitrogen in the form of ammonium, which could cross feed into another bacterium. This study provides greater insight into the microbial metabolism of MAs in the marine environment and how it may affect both nutrient flow within marine surface waters and the flux of these climatically important compounds into the atmosphere.

Genome sequence of Halorhabdus tiamatea, the first archaeon isolated from a deep-sea anoxic brine lake.

KAUST Repository

Antunes, Andre

2011-09-01

We present the draft genome of Halorhabdus tiamatea, the first member of the Archaea ever isolated from a deep-sea anoxic brine. Genome comparison with Halorhabdus utahensis revealed some striking differences, including a marked increase in genes associated with transmembrane transport and putative genes for a trehalose synthase and a lactate dehydrogenase.

Genome sequence of Halorhabdus tiamatea, the first archaeon isolated from a deep-sea anoxic brine lake.

KAUST Repository

Antunes, Andre; Alam, Intikhab; Bajic, Vladimir B.; Stingl, Ulrich

2011-01-01

We present the draft genome of Halorhabdus tiamatea, the first member of the Archaea ever isolated from a deep-sea anoxic brine. Genome comparison with Halorhabdus utahensis revealed some striking differences, including a marked increase in genes associated with transmembrane transport and putative genes for a trehalose synthase and a lactate dehydrogenase.

The reduction of U(VI) on corroded iron under anoxic conditions

International Nuclear Information System (INIS)

Cui, D.; Spahiu, K.

2002-01-01

The corrosion of iron and the interaction between corroded iron and U(VI) in anoxic conditions were investigated. The anoxic conditions were obtained by flushing an 99.97% Ar-0.03% CO 2 gas mixture through the test vessel, in which an oxygen trap and six reaction bottles containing synthetic groundwater (10 mM NaCl and 2 mM HCO 3 - .) were placed. The dark-green coloured corrosion product, formed on iron surface after three months corrosion in synthetic groundwater solutions, was identified by powder X-ray diffraction to be carbonate green rust, Fe 4 II Fe 2 III (OH) 12 CO 3 . The iron foil that reacted in a solution (10 ppm U(VI), 10 mM NaCl and 2 mM HCO 3 - ) for three months was analysed by SEM-EDS. The result shows that: (i) an uneven layer of carbonate green rust (1-5 μm thick) formed on the metallic iron; (ii) a thin (0.3 μm) uranium-rich layer deposited on top of the carbonate green rust layer; and (iii) some UO 2 crystals (3-5 μm sized) on the thin uranium layer. The experimental results proved that the U(VI) removal capacity of metal iron is not hindered by formation of a layer of carbonate green rust on the iron. Tests with cast iron and pure iron indicate that they have similar U(VI) removal capacities. At the end of experiment, U concentrations in solution approached the solubility of UO 2 (s), 10 -8 M. The stability of the carbonate green rust at the experimental conditions, pH, E h , [Fe 2+ ] and [HCO 3 - ], is discussed. (orig.)

Influence of abiotic factors on bacterial proliferation and anoxic survival of the sea mussel Mytilus edulis L.

NARCIS (Netherlands)

Babarro, J.M.F.; De Zwaan, A.

2002-01-01

The effect of several abiotic factors (salinity, temperature and pH) on bacterial proliferation and survival time of the sea mussel Mytilus edulis L. were studied under anoxic incubations. In addition, the presence in the incubation media of ammonium and the volatile fatty acids propionate and

Enhanced nitrogen removal from electroplating tail wastewater through two-staged anoxic-oxic (A/O) process.

Science.gov (United States)

Yan, Xinmei; Zhu, Chunyan; Huang, Bin; Yan, Qun; Zhang, Guangsheng

2018-01-01

Consisted of anaerobic (ANA), anoxic-1 (AN1), aerobic-1 (AE1), anoxic-2 (AN2), aerobic-2 (AE2) reactors and sediment tank, the two-staged A/O process was applied for depth treatment of electroplating tail wastewater with high electrical conductivity and large amounts of ammonia nitrogen. It was found that the NH 4 + -N and COD removal efficiencies reached 97.11% and 83.00%, respectively. Besides, the short-term salinity shock of the control, AE1 and AE2 indicated that AE1 and AE2 have better resistance to high salinity when the concentration of NaCl ranged from 1 to 10g/L. Meanwhile, it was found through high-throughput sequencing that bacteria genus Nitrosomonas, Nitrospira and Thauera, which are capable of nitrogen removal, were enriched in the two-staged A/O process. Moreover, both salt-tolerant bacteria and halophili bacteria were also found in the combined process. Therefore, microbial community within the two-staged A/O process could be acclimated to high electrical conductivity, and adapted for electroplating tail wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Projecting Marine Mammal Distribution in a Changing Climate

Directory of Open Access Journals (Sweden)

Gregory K. Silber

2017-12-01

Full Text Available Climate-related shifts in marine mammal range and distribution have been observed in some populations; however, the nature and magnitude of future responses are uncertain in novel environments projected under climate change. This poses a challenge for agencies charged with management and conservation of these species. Specialized diets, restricted ranges, or reliance on specific substrates or sites (e.g., for pupping make many marine mammal populations particularly vulnerable to climate change. High-latitude, predominantly ice-obligate, species have experienced some of the largest changes in habitat and distribution and these are expected to continue. Efforts to predict and project marine mammal distributions to date have emphasized data-driven statistical habitat models. These have proven successful for short time-scale (e.g., seasonal management activities, but confidence that such relationships will hold for multi-decade projections and novel environments is limited. Recent advances in mechanistic modeling of marine mammals (i.e., models that rely on robust physiological and ecological principles expected to hold under climate change may address this limitation. The success of such approaches rests on continued advances in marine mammal ecology, behavior, and physiology together with improved regional climate projections. The broad scope of this challenge suggests initial priorities be placed on vulnerable species or populations (those already experiencing declines or projected to undergo ecological shifts resulting from climate changes that are consistent across climate projections and species or populations for which ample data already exist (with the hope that these may inform climate change sensitivities in less well observed species or populations elsewhere. The sustained monitoring networks, novel observations, and modeling advances required to more confidently project marine mammal distributions in a changing climate will ultimately

Anoxic Activated Sludge Monitoring with Combined Nitrate and Titrimetric Measurements

DEFF Research Database (Denmark)

Petersen, B.; Gernaey, Krist; Vanrolleghem, P.A.

2002-01-01

was with the carbon source in excess, since excess nitrate provoked nitrite build-up thereby complicating the data interpretation. A conceptual model could quantitatively describe the experimental observations and thus link the experimentally measured proton production with the consumption of electron acceptor......An experimental procedure for anoxic activated sludge monitoring with combined nitrate and titrimetric measurements is proposed and evaluated successfully with two known carbon sources, (-)acetate and dextrose. For nitrate measurements an ion-selective nitrate electrode is applied to allow...... for frequent measurements, and thereby the possibility for detailed determination of the denitrification biokinetics. An internal nitrate electrode calibration is implemented in the experiments to avoid the often-encountered electrode drift problem. It was observed that the best experimental design...

Hydrologic Control on Bacterial Nitrogen Fixation in the Holocene Black Sea

Science.gov (United States)

Fulton, J. M.; Arthur, M. A.; Freeman, K. H.

2008-12-01

Stratified oceans of the Phanerozoic Oceanic Anoxic Events apparently were dominated by bacterial nitrogen fixation. Decreased marine N:P nutrient ratios resulting from increased denitrification and decreased phosphate burial efficiency under anoxic waters drove this nutrient regime. This model is upheld by the presence of cyanobacterial hopanoid biomarkers in sedimentary records and δ15N values indicative of nitrogen fixation. However, in the largest modern redox-stratified marine basin, the Black Sea, bacterial nitrogen fixation seems to be only a minor contributor to the nitrogen cycle. In this study, we use geochemical proxies to evaluate the role of bacterial nitrogen fixation during the deposition of the Holocene Black Sea sapropel, starting 7.8 ka. We report compound-specific nitrogen and carbon stable isotope values of pyropheophytin a, a chlorophyll degradation product, and bacteriochlorophyll e produced by green sulfur bacteria. We also present the surprising finding of scytonemin, a pigment produced only by filamentous cyanobacteria exposed to ultraviolet radiation, in certain intervals in these sediments. In the Holocene, nitrogen fixation in the Black Sea is most prominent during times of reduced river water influx. This directly decreases the external flux of nitrate into the surface waters. Reduced freshwater influx also decreases the volume of low salinity water dispersed around the sea by the Rim Current, allowing the chemocline to shoal along the margins. Previous geochemical studies have described this changing chemocline geometry. The exposure of shallow water sediments to anoxic waters further stimulates nitrogen fixation by releasing more phosphorus to the system. Nitrogen fixation is recorded in the sediments as bulk and compound-specific pyropheophytin a δ15N values near 0 ‰ and -5 ‰, respectively. We have also detected scytonemin in two intervals characterized by especially low δ15N values. This compound suggests abundant filamentous

Nitrogen cycle feedbacks as a control on euxinia in the mid-Proterozoic ocean.

Science.gov (United States)

Boyle, R A; Clark, J R; Poulton, S W; Shields-Zhou, G; Canfield, D E; Lenton, T M

2013-01-01

Geochemical evidence invokes anoxic deep oceans until the terminal Neoproterozoic ~0.55 Ma, despite oxygenation of Earth's atmosphere nearly 2 Gyr earlier. Marine sediments from the intervening period suggest predominantly ferruginous (anoxic Fe(II)-rich) waters, interspersed with euxinia (anoxic H(2)S-rich conditions) along productive continental margins. Today, sustained biotic H(2)S production requires NO(3)(-) depletion because denitrifiers outcompete sulphate reducers. Thus, euxinia is rare, only occurring concurrently with (steady state) organic carbon availability when N(2)-fixers dominate the production in the photic zone. Here we use a simple box model of a generic Proterozoic coastal upwelling zone to show how these feedbacks caused the mid-Proterozoic ocean to exhibit a spatial/temporal separation between two states: photic zone NO(3)(-) with denitrification in lower anoxic waters, and N(2)-fixation-driven production overlying euxinia. Interchange between these states likely explains the varying H(2)S concentration implied by existing data, which persisted until the Neoproterozoic oxygenation event gave rise to modern marine biogeochemistry.

Functional coupling of glycolysis and phosphocreatine utilization in anoxic fish muscle. : An in vivo 31P NMR study

NARCIS (Netherlands)

Van Waarde, A; Van den Thillart, G; Erkelens, Cees; Addink, A; Lugtenburg, J

1990-01-01

Three fish species with different strategies for anoxic survival (goldfish, tilapia, and common carp) were exposed to environmental anoxia (4, 3, and 1 h, respectively). The concentrations of high energy phosphate compounds and inorganic phosphate, besides the intracellular pH in the epaxial muscle

Largest College Endowments, 2011

Science.gov (United States)

Chronicle of Higher Education, 2012

2012-01-01

Of all endowments valued at more than $250-million, the UCLA Foundation had the highest rate of growth over the previous year, at 49 percent. This article presents a table of the largest college endowments in 2011. The table covers the "rank," "institution," "market value as of June 30, 2011," and "1-year change" of institutions participating in…

Combining of radionuclides with constituent materials of marine algae

International Nuclear Information System (INIS)

Nakamura, Ryoichi; Nakahara, Motokazu; Ishii, Toshiaki; Ueda, Taishi; Shimizu, Chiaki.

1979-01-01

The relations between the accumulation-elimination of radionuclides and the constituent materials of marine algae were studied to determine more precisely the mechanism of the radioactive contamination of marine organisms. This will increase the information about the behavior of radionuclides in marine organisms in relation to the environmental conditions (temperature, physico-chemical state of radioisotope, and so on) and the biological conditions (feeding habits, species, and so on). Eisenia contaminated by 137 Cs and 106 Ru- 106 Rh was fractionated by solvent extraction into 6 fractions. The largest portion of 137 Cs was in the boiling water fraction; 106 Ru- 106 Rh was most extracted by 24% KOH solution. Elution patterns by Sephadex G-100 gel-filtration of samples differed largely from each other, both among the 3 kinds of radionuclides and between the 2 species of the algae. Therefore, the accumulation of the radionuclides by the marine algae was proved to be not only due to a physical absorption to the surface of the algae but also to the biological combining of the radionuclides with the constituents of the algae. Furthermore, it was found that radionuclides which combine with a few constituents of alga are not eliminated equally. This is considered to be useful for the physiological analysis of elimination curves. (author)

Marine biodiversity of Aotearoa New Zealand.

Science.gov (United States)

Gordon, Dennis P; Beaumont, Jennifer; MacDiarmid, Alison; Robertson, Donald A; Ahyong, Shane T

2010-08-02

The marine-biodiversity assessment of New Zealand (Aotearoa as known to Māori) is confined to the 200 nautical-mile boundary of the Exclusive Economic Zone, which, at 4.2 million km(2), is one of the largest in the world. It spans 30 degrees of latitude and includes a high diversity of seafloor relief, including a trench 10 km deep. Much of this region remains unexplored biologically, especially the 50% of the EEZ deeper than 2,000 m. Knowledge of the marine biota is based on more than 200 years of marine exploration in the region. The major oceanographic data repository is the National Institute of Water and Atmospheric Research (NIWA), which is involved in several Census of Marine Life field projects and is the location of the Southwestern Pacific Regional OBIS Node; NIWA is also data manager and custodian for fisheries research data owned by the Ministry of Fisheries. Related data sources cover alien species, environmental measures, and historical information. Museum collections in New Zealand hold more than 800,000 registered lots representing several million specimens. During the past decade, 220 taxonomic specialists (85 marine) from 18 countries have been engaged in a project to review New Zealand's entire biodiversity. The above-mentioned marine information sources, published literature, and reports were scrutinized to give the results summarized here for the first time (current to 2010), including data on endemism and invasive species. There are 17,135 living species in the EEZ. This diversity includes 4,315 known undescribed species in collections. Species diversity for the most intensively studied phylum-level taxa (Porifera, Cnidaria, Mollusca, Brachiopoda, Bryozoa, Kinorhyncha, Echinodermata, Chordata) is more or less equivalent to that in the ERMS (European Register of Marine Species) region, which is 5.5 times larger in area than the New Zealand EEZ. The implication is that, when all other New Zealand phyla are equally well studied, total marine

Biodiversity protection and sustainable management of coastal areas: The Marine Protected Area of Egadi Islands

International Nuclear Information System (INIS)

Donati, Stefano

2015-01-01

The Marine Protected Area of Egadi Islands, northwest coast of Sicily Island, is the largest area in the Mediterranean Sea, stretching over with its 53,992 hectares. Established in 1991, since 2001 it is managed by the Municipality of Favignana on behalf of the Italian Ministry for the Environment, Land and Sea. The Egadi’s archipelago is located in the Strait of Sicily, and includes the islands of Favignana, Levanzo, Marettimo and the islets of Formica and Maraone. The institutional mission of the Marine Protected Area is the protection and enhancement of the marine environment, environmental education, awareness and information of users, research and monitoring, integrated management of the coastal zone, and the promotion of sustainable development, with particular reference to the eco-compatibility of tourism [it

Kinetic modelling of bentonite-canister interaction. Long-term predictions of copper canister corrosion under oxic and anoxic conditions

Energy Technology Data Exchange (ETDEWEB)

Wersin, P; Spahiu, K; Bruno, J [MBT Tecnologia Ambiental, Cerdanyola (Spain)

1994-09-01

A new modelling approach for canister corrosion which emphasises chemical processes and diffusion at the bentonite-canister interface is presented. From the geochemical boundary conditions corrosion rates for both an anoxic case and an oxic case are derived and uncertainties thereof are estimated via sensitivity analyses. Time scales of corrosion are assessed by including calculations of the evolution of redox potential in the near field and pitting corrosion. This indicates realistic corrosion depths in the range of 10{sup -7} and 4*10{sup -5} mm/yr, respectively for anoxic and oxic corrosion. Taking conservative estimates, depths are increased by a factor of about 200 for both cases. From these predictions it is suggested that copper canister corrosion does not constitute a problem for repository safety, although certain factors such as temperature and radiolysis have not been explicitly included. The possible effect of bacterial processes on corrosion should be further investigated as it might enhance locally the described redox process. 35 refs, 11 figs, 6 tabs.

Kinetic modelling of bentonite-canister interaction. Long-term predictions of copper canister corrosion under oxic and anoxic conditions

International Nuclear Information System (INIS)

Wersin, P.; Spahiu, K.; Bruno, J.

1994-09-01

A new modelling approach for canister corrosion which emphasises chemical processes and diffusion at the bentonite-canister interface is presented. From the geochemical boundary conditions corrosion rates for both an anoxic case and an oxic case are derived and uncertainties thereof are estimated via sensitivity analyses. Time scales of corrosion are assessed by including calculations of the evolution of redox potential in the near field and pitting corrosion. This indicates realistic corrosion depths in the range of 10 -7 and 4*10 -5 mm/yr, respectively for anoxic and oxic corrosion. Taking conservative estimates, depths are increased by a factor of about 200 for both cases. From these predictions it is suggested that copper canister corrosion does not constitute a problem for repository safety, although certain factors such as temperature and radiolysis have not been explicitly included. The possible effect of bacterial processes on corrosion should be further investigated as it might enhance locally the described redox process. 35 refs, 11 figs, 6 tabs

Largest particle detector nearing completion

CERN Multimedia

2006-01-01

"Construction of another part of the Large Hadron Collider (LHC), the worl's largest particle accelerator at CERN in Switzerland, is nearing completion. The Compact Muon Solenoid (CMS) is oner of the LHC project's four large particle detectors. (1/2 page)

Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

Science.gov (United States)

Whiteside, Jessica H.; Olsen, Paul E.; Eglinton, Timothy; Brookfield, Michael E.; Sambrotto, Raymond N.

2010-01-01

A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date. PMID:20308590

Marine lake as in situ laboratory for studies of organic matter influence on speciation and distribution of trace metals

Science.gov (United States)

Mlakar, Marina; Fiket, Željka; Geček, Sunčana; Cukrov, Neven; Cuculić, Vlado

2015-07-01

Karst marine lakes are unique marine systems, also recognized as in situ "laboratories" in which geochemical processes on a different scale compared to the open sea, can be observed. In this study, organic matter cycle and its impact on distribution of trace metals in the marine lake Mir, located on Dugi Otok Island, in the central part of the eastern Adriatic Sea, was investigated for the first time. Studied marine lake is small, isolated, shallow basin, with limited communication with the open sea. Intense spatial and seasonal variations of organic matter, dissolved and particulate (DOC, POC), and dissolved trace metals concentrations in the water column of the Lake are governed predominantly by natural processes. Enhanced oxygen consumption in the Lake during summer season, high DOC and POC concentrations and low redox potential result in occasional occurrence of anoxic conditions in the bottom layers with appearance of sulfur species. Speciation modeling showed that dissolved trace metals Cu, Pb and Zn, are mostly bound to organic matter, while Cd, Co and Ni are present predominantly as free ions and inorganic complexes. Trace metals removal from the water column and their retention in the sediment was found to depend on the nature of the relationship between specific metal and organic or inorganic phases, sulfides, Fe-oxyhydroxydes or biogenic calcite. The above is reflected in the composition of the sediments, which are, in addition to influence of karstic background and bathymetry of the basin, significantly affected by accumulation of detritus at the bottom of the Lake.

Importance of the autumn overturn and anoxic conditions in the hypolimnion for the annual methane emissions from a temperate lake.

Science.gov (United States)

Encinas Fernández, Jorge; Peeters, Frank; Hofmann, Hilmar

2014-07-01

Changes in the budget of dissolved methane measured in a small temperate lake over 1 year indicate that anoxic conditions in the hypolimnion and the autumn overturn period represent key factors for the overall annual methane emissions from lakes. During periods of stable stratification, large amounts of methane accumulate in anoxic deep waters. Approximately 46% of the stored methane was emitted during the autumn overturn, contributing ∼80% of the annual diffusive methane emissions to the atmosphere. After the overturn period, the entire water column was oxic, and only 1% of the original quantity of methane remained in the water column. Current estimates of global methane emissions assume that all of the stored methane is released, whereas several studies of individual lakes have suggested that a major fraction of the stored methane is oxidized during overturns. Our results provide evidence that not all of the stored methane is released to the atmosphere during the overturn period. However, the fraction of stored methane emitted to the atmosphere during overturn may be substantially larger and the fraction of stored methane oxidized may be smaller than in the previous studies suggesting high oxidation losses of methane. The development or change in the vertical extent and duration of the anoxic hypolimnion, which can represent the main source of annual methane emissions from small lakes, may be an important aspect to consider for impact assessments of climate warming on the methane emissions from lakes.

Anoxic or aerial survival of bivalves and other euryoxic invertebrates as a useful response to environmental stress - A comprehensive review

NARCIS (Netherlands)

De Zwaan, A.; Eertman, R.H.M.

1996-01-01

Laboratory and field studies have demonstrated the applicability of anoxic/aerial survival as an early warning indicator of contaminant induced stress. The effects of xenobiotics, including heavy metals, organometals and organics as well as contaminated field sediments have been investigated. The

Accumulation of trace metals in coastal marine organisms

International Nuclear Information System (INIS)

Weers, A.W. van; Raaphorst, J.G. van

1980-01-01

ECN at Petten carries out a survey on the occurrence of trace metals in coastal marine organisms. The survey is aimed to provide an estimate of concentration factors in local marine organisms for neutron activation products released as low-level liquid radioactive waste into the North Sea. The organisms studied are red and brown seaweed, edible mussels ans shrimp. A summary of the results of analyses of iron, cobalt, zinc, silver and antimony in these organisms is presented. Concentration factors derived from mean stable-element concentrations range from about 50 for Sb in red seaweed and shrimp to about 10 4 for Fe in red seaweed and mussels. The largest variation is shown for zinc in seaweed, which variation is seasonal and most pronounced in brown seaweed. A discussion of the data is presented in relation to data from other West-European coastal areas and to data used for the radiological assessment of deep sea disposal of radioactive waste

Unexpected and novel putative viruses in the sediments of a deep-dark permanently anoxic freshwater habitat

OpenAIRE

Borrel, Guillaume; Colombet, Jonathan; Robin, Agnès; Lehours, Anne-Catherine; Prangishvili, David; Sime-Ngando, Télesphore

2012-01-01

Morphological diversity, abundance and community structure of viruses were examined in the deep and anoxic sediments of the volcanic Lake Pavin (France). The sediment core, encompassing 130 years of sedimentation, was subsampled every centimeter. High viral abundances were recorded and correlated to prokaryotic densities. Abundances of viruses and prokaryotes decreased with the depth, contrasting the pattern of virus-to-prokaryote ratio. According to fingerprint analyses, the community struct...

Global change in the trophic functioning of marine food webs.

Directory of Open Access Journals (Sweden)

Aurore Maureaud

Full Text Available The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950-2010 time-periods. Global trends were identified and cluster analyses were used to characterize the variability of trends between ecosystems. Results showed that the most common pattern over the study period is a global decrease in TCI, while the ECI indicator tends to increase. Thus, changes in species assemblages would induce faster and apparently more efficient biomass transfers in marine food webs. Results also suggested that the main driver of change over that period had been the large increase in fishing pressure. The largest changes occurred in ecosystems where 'fishing down the marine food web' are most intensive.

Biological anoxic treatment of O2-free VOC emissions from the petrochemical industry: A proof of concept study

International Nuclear Information System (INIS)

Muñoz, Raúl; Souza, Theo S.O.; Glittmann, Lina; Pérez, Rebeca; Quijano, Guillermo

2013-01-01

Highlights: • The treatment of O 2 -free VOC emissions can be done by means of denitrifying processes. •Toluene vapors were successfully removed under anoxic denitrifying conditions. • A high bacterial diversity was observed. • Actinobacteria and Proteobacteria were the predominant phyla. • The nature and number of metabolites accumulated varied with the toluene load -- Abstract: An innovative biofiltration technology based on anoxic biodegradation was proposed in this work for the treatment of inert VOC-laden emissions from the petrochemical industry. Anoxic biofiltration does not require conventional O 2 supply to mineralize VOCs, which increases process safety and allows for the reuse of the residual gas for inertization purposes in plant. The potential of this technology was evaluated in a biotrickling filter using toluene as a model VOC at loads of 3, 5, 12 and 34 g m −3 h −1 (corresponding to empty bed residence times of 16, 8, 4 and 1.3 min) with a maximum elimination capacity of ∼3 g m −3 h −1 . However, significant differences in the nature and number of metabolites accumulated at each toluene load tested were observed, o- and p-cresol being detected only at 34 g m −3 h −1 , while benzyl alcohol, benzaldehyde and phenol were detected at lower loads. A complete toluene removal was maintained after increasing the inlet toluene concentration from 0.5 to 1 g m −3 (which entailed a loading rate increase from 3 to 6 g m −3 h −1 ), indicating that the system was limited by mass transfer rather than by biological activity. A high bacterial diversity was observed, the predominant phyla being Actinobacteria and Proteobacteria

Extraordinary aggressive behavior from the giant coral reef fish, Bolbometopon muricatum, in a remote marine reserve.

Directory of Open Access Journals (Sweden)

Roldan C Muñoz

Full Text Available Human impacts to terrestrial and marine communities are widespread and typically begin with the local extirpation of large-bodied animals. In the marine environment, few pristine areas relatively free of human impact remain to provide baselines of ecosystem function and goals for restoration efforts. Recent comparisons of remote and/or protected coral reefs versus impacted sites suggest remote systems are dominated by apex predators, yet in these systems the ecological role of non-predatory, large-bodied, highly vulnerable species such as the giant bumphead parrotfish (Bolbometopon muricatum has received less attention. Overfishing of Bolbometopon has lead to precipitous declines in population density and avoidance of humans throughout its range, contributing to its status as a candidate species under the U. S. Endangered Species Act and limiting opportunities to study unexploited populations. Here we show that extraordinary ecological processes, such as violent headbutting contests by the world's largest parrotfish, can be revealed by studying unexploited ecosystems, such as the coral reefs of Wake Atoll where we studied an abundant population of Bolbometopon. Bolbometopon is among the largest of coral reef fishes and is a well known, charismatic species, yet to our knowledge, no scientific documentation of ritualized headbutting exists for marine fishes. Our observations of aggressive headbutting by Bolbometopon underscore that remote locations and marine reserves, by inhibiting negative responses to human observers and by allowing the persistence of historical conditions, can provide valuable opportunities to study ecosystems in their natural state, thereby facilitating the discovery, conservation, and interpretation of a range of sometimes remarkable behavioral and ecological processes.

Extraordinary aggressive behavior from the giant coral reef fish, Bolbometopon muricatum, in a remote marine reserve.

Science.gov (United States)

Muñoz, Roldan C; Zgliczynski, Brian J; Laughlin, Joseph L; Teer, Bradford Z

2012-01-01

Human impacts to terrestrial and marine communities are widespread and typically begin with the local extirpation of large-bodied animals. In the marine environment, few pristine areas relatively free of human impact remain to provide baselines of ecosystem function and goals for restoration efforts. Recent comparisons of remote and/or protected coral reefs versus impacted sites suggest remote systems are dominated by apex predators, yet in these systems the ecological role of non-predatory, large-bodied, highly vulnerable species such as the giant bumphead parrotfish (Bolbometopon muricatum) has received less attention. Overfishing of Bolbometopon has lead to precipitous declines in population density and avoidance of humans throughout its range, contributing to its status as a candidate species under the U. S. Endangered Species Act and limiting opportunities to study unexploited populations. Here we show that extraordinary ecological processes, such as violent headbutting contests by the world's largest parrotfish, can be revealed by studying unexploited ecosystems, such as the coral reefs of Wake Atoll where we studied an abundant population of Bolbometopon. Bolbometopon is among the largest of coral reef fishes and is a well known, charismatic species, yet to our knowledge, no scientific documentation of ritualized headbutting exists for marine fishes. Our observations of aggressive headbutting by Bolbometopon underscore that remote locations and marine reserves, by inhibiting negative responses to human observers and by allowing the persistence of historical conditions, can provide valuable opportunities to study ecosystems in their natural state, thereby facilitating the discovery, conservation, and interpretation of a range of sometimes remarkable behavioral and ecological processes.

The study of a pilot-scale aerobic/Fenton/anoxic/aerobic process system for the treatment of landfill leachate.

Science.gov (United States)

Hu, Wenyong; Zhou, Yu; Min, Xiaobo; Liu, Jingyi; Li, Xinyu; Luo, Lin; Zhang, Jiachao; Mao, Qiming; Chai, Liyuan; Zhou, YaoYu

2017-06-29

In this study, a combined aerobic-Fenton-anoxic/aerobic system was designed for the remediation of raw landfill leachate in a pilot-scale experiment. This system included (i) a granular sludge biological oxidation procedure that achieves the accumulation of nitrite nitrogen ([Formula: see text]) under aerobic conditions; (ii) a Fenton process that improves the biodegradability of the biotreated leachate and (iii) an activated sludge biological oxidation component under anoxic and aerobic conditions. Additionally, a shortcut nitrification and denitrification pathway was achieved. The effects of free ammonia, temperature and pH on nitrite accumulation were discussed. The change in the biochemical oxygen demand/chemical oxygen demand ratio of the effluent after shortcut nitrification was also analysed. The microbial community in the reactor were also investigated. The problem of the lack of carbon source in the denitrification process can be solved by the Fenton reagent method. Moreover, it was beneficial to achieving nitrogen removal as well as the more extensive removal of organic matter. The treatment strategy employed in this study exhibited good results and provided the potential practical application for treating landfill leachate.

Synopsis of French experimental and in situ research on the terrestrial and marine behavior of Tc

International Nuclear Information System (INIS)

Masson, M.; Patti, F.; Colle, C.; Roucoux, P.; Grauby, A.; Saas, A.

1989-01-01

Terrestrial environment studies have been essentially concerned with the evolution of soil deposition and soil-plant transfers. Experimentally determined coefficients of distribution in soils are low: 60-80% of Tc remains hydrosoluble during the first months. Technetium emissions resulting from microbiological activity have been quantified. Antagonistic effects on Mo and Tc retention by soils are dependent on their respective concentrations. Four areas of soil-plant transfers have been studied: (1) root absorption kinetics relative to deposition of Tc, (2) interaction of stable Mo (environmental parameter) with the transfer of Tc to plants, (3) interaction of some long-lived radioisotopes (effluent parameters) with the transfer of Tc to plants, and (4) long-term soil-plant transfer and aging of deposited material. Of aquatic systems, only the marine environment has been studied. Under anoxic conditions in the presence of reducing sediments, the distribution coefficients (Kd) were very high (10(3)). Concentration factors (CF) from water to organisms were generally very low (1 to 10); however, CF greater than 1000 have been observed for some biota such as macrophytic brown algae, worms and lobsters. Biochemical analysis showed that Tc was essentially free and partially bonded to proteins. The transfer factors between sediments and species were very low (TF less than 0.5). The biological half-time was determined in some marine organisms that had accumulated Tc from water, food or sediments; the loss is biphasic. Uptake in edible parts was low. The physiochemical form affects the accumulation and loss of Tc. Analyses have quantified 99Tc in marine fauna and biota in the English Channel in relation with releases of the reprocessing plant of La Hague. Brown algae are the best bioindicators for following 99Tc dispersion in marine ecosystems. 24 references

Microbial diversity of an anoxic zone of a hydroelectric power station reservoir in Brazilian Amazonia.

Science.gov (United States)

Graças, Diego A; Miranda, Paulo R; Baraúna, Rafael A; McCulloch, John A; Ghilardi, Rubens; Schneider, Maria Paula C; Silva, Artur

2011-11-01

Microbial diversity was evaluated in an anoxic zone of Tucuruí Hydroelectric Power Station reservoir in Brazilian Amazonia using a culture-independent approach by amplifying and sequencing fragments of the 16S rRNA gene using metagenomic DNA as a template. Samples obtained from the photic, aphotic (40 m) and sediment (60 m) layers were used to construct six 16S rDNA libraries containing a total of 1,152 clones. The sediment, aphotic and photic layers presented 64, 33 and 35 unique archaeal operational taxonomic units (OTUs). The estimated richness of these layers was evaluated to be 153, 106 and 79 archaeal OTUs, respectively, using the abundance-based coverage estimator (ACE) and 114, 83 and 77 OTUs using the Chao1 estimator. For bacterial sequences, 114, 69 and 57 OTUs were found in the sediment, aphotic and photic layers, which presented estimated richnesses of 1,414, 522 and 197 OTUs (ACE) and 1,059, 1,014 and 148 OTUs (Chao1), respectively. Phylogenetic analyses of the sequences obtained revealed a high richness of microorganisms which participate in the carbon cycle, namely, methanogenic archaea and methanotrophic proteobacteria. Most sequences obtained belong to non-culturable prokaryotes. The present study offers the first glimpse of the huge microbial diversity of an anoxic area of a man-made lacustrine environment in the tropics.

Fate and behavior of dissolved organic matter in a submerged anoxic-aerobic membrane bioreactor (MBR).

Science.gov (United States)

Zhang, Dongqing; Trzcinski, Antoine Prandota; Luo, Jinxue; Stuckey, David C; Tan, Soon Keat

2018-02-01

In this study, the production, composition, and characteristics of dissolved organic matter (DOM) in an anoxic-aerobic submerged membrane bioreactor (MBR) were investigated. The average concentrations of proteins and carbohydrates in the MBR aerobic stage were 3.96 ± 0.28 and 8.36 ± 0.89 mg/L, respectively. After membrane filtration, these values decreased to 2.9 ± 0.2 and 2.8 ± 0.2 mg/L, respectively. High performance size exclusion chromatograph (HP-SEC) analysis indicated a bimodal molecular weight (MW) distribution of DOMs, and that the intensities of all the peaks were reduced in the MBR effluent compared to the influent. Three-dimensional fluorescence excitation emission matrix (FEEM) indicated that fulvic and humic acid-like substances were the predominant DOMs in biological treatment processes. Precise identification and characterization of low-MW DOMs was carried out using gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis indicated that the highest peak numbers (170) were found in the anoxic stage, and 54 (32%) compounds were identified with a similarity greater than 80%. Alkanes (28), esters (11), and aromatics (7) were the main compounds detected. DOMs exhibited both biodegradable and recalcitrant characteristics. There were noticeable differences in the low-MW DOMs present down the treatment process train in terms of numbers, concentrations, molecular weight, biodegradability, and recalcitrance.

Assessing the Long-Term Efficacy of Geotextiles in Preserving Archaeological Wooden Shipwrecks in the Marine Environment

Science.gov (United States)

Pournou, Anastasia

2017-09-01

Archaeological wood cannot be found preserved in the marine ecosystem unless it is buried in anoxic or dysoxic sediments. These habitats do not allow the growth and activity of wood degraders, and thus wooden shipwrecks can survive within these environments for centuries. However, due to natural factors or anthropogenic interventions wood can be re-exposed to the oxygenated water column, where it disintegrates rapidly. In such cases, in situ preservation becomes a main priority, as lifting and conservation are not usually feasible. One of the most common in situ preservation methods is the covering of wood with geotextiles. To date however, even though this method has been used worldwide the past decades, its long-term performance and effectiveness hasn't been evaluated. This work presents, for the first time, results on the efficacy of geotextiles used for 12 years on a shipwreck found in the Mediterranean. Fabric performance was evaluated based on wreck timbers condition, its physical, mechanical and hydraulic properties and the ecological and hydrographical profile of the underwater site created, following its application. Obtained results demonstrated that wreck timbers covered with geotextiles did not show signs of attack during the 12 years of in situ preservation. Geotextiles properties were found to be adequately retained when compared with properties of new unused geotextiles. The fabric had entrapped sediment and was colonised by the local flora and fauna, re-establishing anoxic conditions. This work showed that geotextiles can successfully preserve in situ wooden shipwrecks in high biodeterioration risk environments for at least a 10 year period.

Assessing the Long-Term Efficacy of Geotextiles in Preserving Archaeological Wooden Shipwrecks in the Marine Environment

Science.gov (United States)

Pournou, Anastasia

2018-04-01

Archaeological wood cannot be found preserved in the marine ecosystem unless it is buried in anoxic or dysoxic sediments. These habitats do not allow the growth and activity of wood degraders, and thus wooden shipwrecks can survive within these environments for centuries. However, due to natural factors or anthropogenic interventions wood can be re-exposed to the oxygenated water column, where it disintegrates rapidly. In such cases, in situ preservation becomes a main priority, as lifting and conservation are not usually feasible. One of the most common in situ preservation methods is the covering of wood with geotextiles. To date however, even though this method has been used worldwide the past decades, its long-term performance and effectiveness hasn't been evaluated. This work presents, for the first time, results on the efficacy of geotextiles used for 12 years on a shipwreck found in the Mediterranean. Fabric performance was evaluated based on wreck timbers condition, its physical, mechanical and hydraulic properties and the ecological and hydrographical profile of the underwater site created, following its application. Obtained results demonstrated that wreck timbers covered with geotextiles did not show signs of attack during the 12 years of in situ preservation. Geotextiles properties were found to be adequately retained when compared with properties of new unused geotextiles. The fabric had entrapped sediment and was colonised by the local flora and fauna, re-establishing anoxic conditions. This work showed that geotextiles can successfully preserve in situ wooden shipwrecks in high biodeterioration risk environments for at least a 10 year period.

Partition of iodine (129I and 127I) isotopes in soils and marine sediments

DEFF Research Database (Denmark)

Hansen, Violeta; Roos, Per; Aldahan, Ala

2011-01-01

Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its......–60% of the total 129I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0–5.5, 127I and 129I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 129I was mostly found to be bound to fulvic acid. Anoxic conditions seem...... environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), 129I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different...

Lethal exposure times of anoxic treatment in eight species of museum pests (fam. Dermestidae, Ptinidae and Tineidae)

DEFF Research Database (Denmark)

Bergh, Jan-Erik; Hansen, Lise Stengaard; Nielsen, Per Væggemose

1999-01-01

Based on surveys of species of museum pest insects commonly found in Fennoscandia, a number of important species were selected for a study of mortality caused by exposure to modified atmosphere (>99.7 % nitrogen). In most of the species 100 % mortality was obtained within 72 hours of exposure....... Preliminary analysis of the results revealed that the larval and pupal stages were most tolerant to the anoxic treatment....

Isoprenoid quinones resolve the stratification of microbial redox processes in a biogeochemical continuum from the photic zone to deep anoxic sediments of the Black Sea.

Science.gov (United States)

Becker, Kevin W; Elling, Felix J; Schröder, Jan M; Lipp, Julius S; Goldhammer, Tobias; Zabel, Matthias; Elvert, Marcus; Overmann, Jörg; Hinrichs, Kai-Uwe

2018-03-09

The stratified water column of the Black Sea serves as a model ecosystem for studying the interactions of microorganisms with major biogeochemical cycles. Here we provide detailed analysis of isoprenoid quinones to study microbial redox processes in the ocean. In a continuum from the photic zone through the chemocline into deep anoxic sediments of the southern Black Sea, diagnostic quinones and inorganic geochemical parameters indicate niche segregation between redox processes and corresponding shifts in microbial community composition. Quinones specific for oxygenic photosynthesis and aerobic respiration dominate oxic waters, while quinones associated with thaumarchaeal ammonia-oxidation and bacterial methanotrophy, respectively, dominate a narrow interval in suboxic waters. Quinone distributions indicate highest metabolic diversity within the anoxic zone, with anoxygenic photosynthesis being a major process in its photic layer. In the dark anoxic layer, quinone profiles indicate occurrence of bacterial sulfur and nitrogen cycling, archaeal methanogenesis, and archaeal methanotrophy. Multiple novel ubiquinone isomers, possibly originating from unidentified intra-aerobic anaerobes, occur in this zone. The respiration modes found in the anoxic zone continue into shallow subsurface sediments, but quinone abundances rapidly decrease within the upper 50 cm below sea floor, reflecting the transition to lower energy availability. In the deep subseafloor sediments, quinone distributions and geochemical profiles indicate archaeal methanogenesis/methanotrophy and potentially bacterial fermentative metabolisms. We observed that sedimentary quinone distributions track lithology, which supports prior hypotheses that deep biosphere community composition and metabolisms are determined by environmental conditions during sediment deposition. Importance Microorganisms play crucial roles in global biogeochemical cycles. Yet, we have only a fragmentary understanding of the diversity

Photogeochemical reactions of manganese under anoxic conditions

Science.gov (United States)

Liu, W.; Yee, N.; Piotrowiak, P.; Falkowski, P. G.

2017-12-01

Photogeochemistry describes reactions involving light and naturally occurring chemical species. These reactions often involve a photo-induced electron transfer that does not occur in the absence of light. Although photogeochemical reactions have been known for decades, they are often ignored in geochemical models. In particular, reactions caused by UV radiation during an ozone free early Earth could have influenced the available oxidation states of manganese. Manganese is one of the most abundant transition metals in the crust and is important in both biology and geology. For example, the presence of manganese (VI) oxides in the geologic record has been used as a proxy for oxygenic photosynthesis; however, we suggest that the high oxidation state of Mn can be produced abiotically by photochemical reactions. Aqueous solutions of manganese (II) as well as suspensions of rhodochrosite (MnCO3) were irradiated under anoxic condition using a 450 W mercury lamp and custom built quartz reaction vessels. The photoreaction of the homogeneous solution of Mn(II) produced H2 gas and akhtenskite (ɛ-MnO2) as the solid product . This product is different than the previously identified birnessite. The irradiation of rhodochrosite suspensions also produced H2 gas and resulted in both a spectral shift as well as morphology changes of the mineral particles in the SEM images. These reactions offer alternative, abiotic pathways for the formation of manganese oxides.

Evidence for complete denitrification in a benthic foraminifer

DEFF Research Database (Denmark)

Risgaard-Petersen, N.; Langezaal, A. M.; Ingvardsen, S.

2006-01-01

zone of the continental shelf off Chile. Given the high abundance of foraminifera in anoxic marine environments1–3, these new findings suggest that foraminifera may play an important role in global nitrogen cycling and indicate that our understanding of the complexity of the marine nitrogen cycle...

Early cenozoic differentiation of polar marine faunas.

Directory of Open Access Journals (Sweden)

J Alistair Crame

Full Text Available The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene-Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability.

Radioanalytical studies of anthropogenic radionuclides in an anoxic fjord

International Nuclear Information System (INIS)

Roos, P.; Holm, E.

1993-01-01

The vertical distribution of 239+240 Pu, 238 Pu, 241 Am, 99 Tc, 137 Cs and 134 Cs has been studied in the permanently super-anoxic Framvaren fjord in southern Norway. The adjacent Helvik fjord (slightly below 14 m depth) was studied with the respect to the same radionuclides as a comparison for their distribution and levels during more normal conditions. Th was studied in both fjords as a representative for actinides in oxidation state +4. Vertical distribution of Pu, Am and Th in Framvaren all show increased concentration with depth. Complex formation with DOC is believed to be the main course for this behaviour. Increasing 232 Th with depth in sediment indicate possible remobilization of this element from the sediments. The limited water exchange between the two fjords is illustrated by the low 238 Pu/ 239+240 Pu ratio and the higher 134 Cs/ 137 Cs ratio in Framvaren fjord. Concentration of 99 Tc in Framvaren is also lower than compared to Helvik fjord. Concentration of 99 Tc in Helvik and Framvaren fjord is approximately constant with depth

Large recovery of fish biomass in a no-take marine reserve.

Directory of Open Access Journals (Sweden)

Octavio Aburto-Oropeza

Full Text Available No-take marine reserves are effective management tools used to restore fish biomass and community structure in areas depleted by overfishing. Cabo Pulmo National Park (CPNP was created in 1995 and is the only well enforced no-take area in the Gulf of California, Mexico, mostly because of widespread support from the local community. In 1999, four years after the establishment of the reserve, there were no significant differences in fish biomass between CPNP (0.75 t ha(-1 on average and other marine protected areas or open access areas in the Gulf of California. By 2009, total fish biomass at CPNP had increased to 4.24 t ha(-1 (absolute biomass increase of 3.49 t ha(-1, or 463%, and the biomass of top predators and carnivores increased by 11 and 4 times, respectively. However, fish biomass did not change significantly in other marine protected areas or open access areas over the same time period. The absolute increase in fish biomass at CPNP within a decade is the largest measured in a marine reserve worldwide, and it is likely due to a combination of social (strong community leadership, social cohesion, effective enforcement and ecological factors. The recovery of fish biomass inside CPNP has resulted in significant economic benefits, indicating that community-managed marine reserves are a viable solution to unsustainable coastal development and fisheries collapse in the Gulf of California and elsewhere.

Understanding the scale of Marine protection in Hawai'i: from community-based management to the remote Northwestern Hawaiian Islands.

Science.gov (United States)

Friedlander, Alan M; Stamoulis, Kostantinos A; Kittinger, John N; Drazen, Jeffrey C; Tissot, Brian N

2014-01-01

Ancient Hawaiians developed a sophisticated natural resource management system that included various forms of spatial management. Today there exists in Hawai'i a variety of spatial marine management strategies along a range of scales, with varying degrees of effectiveness. State-managed no-take areas make up less than 0.4% of nearshore waters, resulting in limited ecological and social benefits. There is increasing interest among communities and coastal stakeholders in integrating aspects of customary Hawaiian knowledge into contemporary co-management. A network of no-take reserves for aquarium fish on Hawai'i Island is a stakeholder-driven, adaptive management strategy that has been successful in achieving ecological objectives and economic benefits. A network of large-scale no-take areas for deepwater (100-400m) bottomfishes suffered from a lack of adequate data during their initiation; however, better technology, more ecological data, and stakeholder input have resulted in improvements and the ecological benefits are becoming clear. Finally, the Papahānaumokuākea Marine National Monument (PMNM) is currently the single largest conservation area in the United States, and one of the largest in the world. It is considered an unqualified success and is managed under a new model of collaborative governance. These case studies allow an examination of the effects of scale on spatial marine management in Hawai'i and beyond that illustrate the advantages and shortcomings of different management strategies. Ultimately a marine spatial planning framework should be applied that incorporates existing marine managed areas to create a holistic, regional, multi-use zoning plan engaging stakeholders at all levels in order to maximize resilience of ecosystems and communities.

Biological anoxic treatment of O{sub 2}-free VOC emissions from the petrochemical industry: A proof of concept study

Energy Technology Data Exchange (ETDEWEB)

Muñoz, Raúl; Souza, Theo S.O. [Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr Mergelina s/n, 47011 Valladolid (Spain); Glittmann, Lina [Ostfalia University of Applied Sciences, Department of Supply Engineering, Wolfenbüttel (Germany); Pérez, Rebeca [Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr Mergelina s/n, 47011 Valladolid (Spain); Quijano, Guillermo [Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr Mergelina s/n, 47011 Valladolid (Spain)

2013-09-15

Highlights: • The treatment of O{sub 2}-free VOC emissions can be done by means of denitrifying processes. •Toluene vapors were successfully removed under anoxic denitrifying conditions. • A high bacterial diversity was observed. • Actinobacteria and Proteobacteria were the predominant phyla. • The nature and number of metabolites accumulated varied with the toluene load -- Abstract: An innovative biofiltration technology based on anoxic biodegradation was proposed in this work for the treatment of inert VOC-laden emissions from the petrochemical industry. Anoxic biofiltration does not require conventional O{sub 2} supply to mineralize VOCs, which increases process safety and allows for the reuse of the residual gas for inertization purposes in plant. The potential of this technology was evaluated in a biotrickling filter using toluene as a model VOC at loads of 3, 5, 12 and 34 g m{sup −3} h{sup −1} (corresponding to empty bed residence times of 16, 8, 4 and 1.3 min) with a maximum elimination capacity of ∼3 g m{sup −3} h{sup −1}. However, significant differences in the nature and number of metabolites accumulated at each toluene load tested were observed, o- and p-cresol being detected only at 34 g m{sup −3} h{sup −1}, while benzyl alcohol, benzaldehyde and phenol were detected at lower loads. A complete toluene removal was maintained after increasing the inlet toluene concentration from 0.5 to 1 g m{sup −3} (which entailed a loading rate increase from 3 to 6 g m{sup −3} h{sup −1}), indicating that the system was limited by mass transfer rather than by biological activity. A high bacterial diversity was observed, the predominant phyla being Actinobacteria and Proteobacteria.

Effects of body temperature on post-anoxic oxidative stress from the perspective of postnatal physiological adaptive processes in rats.

Science.gov (United States)

Kletkiewicz, H; Rogalska, J; Nowakowska, A; Wozniak, A; Mila-Kierzenkowska, C; Caputa, M

2016-04-01

It is well known that decrease in body temperature provides protection to newborns subjected to anoxia/ischemia. We hypothesized that the normal body temperature of 33°C in neonatal rats (4°C below normal body temperature in adults) is in fact a preadaptation to protect CNS from anoxia and further reductions as well as elevations in temperature may be counterproductive. Our experiments aimed to examine the effect of changes in body temperature on oxidative stress development in newborn rats exposed to anoxia. Two-day-old Wistar rats were divided into 4 temperature groups: i. hypothermic at body temperature of 31°C, ii. maintaining physiological neonatal body temperature of 33°C, iii. forced to maintain hyperthermic temperature of 37°C, and i.v. forced to maintain hyperthermic temperature of 39°C. The temperature was controlled starting 15 minutes before and afterword during 10 minutes of anoxia as well as for 2 hours post-anoxia. Cerebral concentrations of lipid peroxidation products malondialdehyde (MDA) and conjugated dienes (CD) and the activities of antioxidant enzymes had been determined post mortem: immediately after anoxia was finished and 3, 7, and 14 days later. There were no post-anoxic changes in the concentration of MDA, CD and in antioxidant enzymes activity in newborn rats kept at their physiological body temperature of 33°C. In contrast, perinatal anoxia at body temperature elevated to 37°C or 39°C as well as under hypothermic conditions (31°C) intensified post-anoxic oxidative stress and depleted the antioxidant pool. Overall, these findings suggest that elevated body temperature (hyperthermia or fever), as well as exceeding cooling beyond the physiological level of body temperature of newborn rats, may extend perinatal anoxia-induced brain lesions. Our findings provide new insights into the role of body temperature in anoxic insult in vivo.

Optimized Environmental Test Sequences to Ensure the Sustainability and Reliability of Marine Weapons

Directory of Open Access Journals (Sweden)

Jung Ho Yang

2014-11-01

Full Text Available In recent years, there has been an increase in the types of marine weapons used in response to diverse hostile threats. However, because marine weapons are only tested under a single set of environmental conditions, failures due to different environmental stresses have been difficult to detect. Hence, this study proposes an environmental test sequence for multi-environment testing. The environmental test sequences for electrical units described in the international standard IEC 60068-1, and for military supply described in the United States national standard MIL-STD-810G were investigated to propose guidelines for the appropriate test sequences. This study demonstrated the need for tests in multiple environments by investigating marine weapon accidents, and evaluated which environmental stresses and test items have the largest impacts on marine weapons using a two-phase quality function deployment (QFD analysis of operational scenarios, environmental stresses, and environmental test items. Integer programming was used to determine the most influential test items and the shortest environmental test time, allowing us to propose optimal test procedures. Based on our analysis, we developed optimal environmental test sequences that could be selected by a test designer.

Marine conservation and accession: the future for the Croatian Adriatic.

Science.gov (United States)

Mackelworth, Peter; Holcer, Draško; Jovanović, Jelena; Fortuna, Caterina

2011-04-01

The European Union (EU) is the world's largest trading bloc and the most influential supra-national organisation in the region. The EU has been the goal for many eastern European States, for Croatia accession remains a priority and underpins many of its national policies. However, entry into the EU requires certain commitments and concessions. In October 2003 the Croatian parliament declared an ecological and fisheries protection zone in the Adriatic. Under pressure the zone was suspended, finally entering into force in March 2008 exempting EU States. There are other marine conflicts between Croatia and the EU, particularly the contested maritime border with Slovenia, and the development of the Croatian fishing fleet in opposition to the Common Fisheries Policy. Conversely, attempts to harmonise Croatian Nature Protection with the EU Habitats Directive, facilitated by pre-accession funding, has galvanised conservation policy. Since 2005 two marine protected areas have been declared, significantly increasing the marine ecosystem under protection. Finally, the development of the Marine Strategy Framework Directive is the latest EU attempt to integrate environmental policy in the maritime realm. This will have an effect not only on member States but neighbouring countries. For marine nature protection to be effective in the region the Adriatic Sea needs to be viewed as a mutually important shared and limited resource not a bargaining chip. Negotiations of the EU and Croatia have been watched closely by the other Balkan States and precedents set in this case have the potential to affect EU expansion to the East.

A Compound-Specific Hydrogen Isotope Record at the Onset of Ocean Anoxic Event 2, Kaiparowits Plateau, Southern Utah

Science.gov (United States)

Todes, J.; Jones, M. M.; Sageman, B. B.; Osburn, M. R.

2017-12-01

Rhythmic lithologic variations (limestone-shale couplets) interpreted to reflect Milankovitch cycles occur at the onset of Ocean Anoxic Event 2 (OAE2) in deposits of the Western Interior Seaway. These couplets have been interpreted to reflect climate cycles: however, the physical mechanism(s) through which climate cycles were translated to the sedimentary record during peak greenhouse conditions remain unsettled. Although glacioeustasy has been considered, variance in surface ocean temperature, ocean circulation, or local hydrology may be more plausible options. Compound-specific hydrogen isotope ratios (δ2H) of n-alkanes and other biomarkers may provide a means to evaluate such mechanisms. Since sedimentary alkanes are direct products of plants and membrane lipid diagenesis and are resistant to secondary hydrogen exchange during thermal maturation at low (chain length distributions suggest low thermal maturity and the possible preservation of primary δ2H values. Short and long chain ­n-alkanes are potentially sourced from planktonic biomass and terrestrial plants, respectively, enabling a comparison of climatic processes between marine and terrestrial settings. Biomarkers, including both steranes and hopanes, are also preserved and reflect putative source organisms and local paleoenvironmental conditions. Facies-specific δ2H analysis will allow for evaluation of changes in the dominant source of atmospheric moisture in the Western Interior during orbitally-forced climate cycles. Organic matter deposited during periods of northerly Boreal influence would have a depleted 2H-isotope composition relative to those deposited during periods of more southerly Tethys influence. In this model, these variations are reflected by lithology - limestone deposition would occur during warm, evaporative Tethys-dominated times, while cooler, wetter Boreal periods would promote shale deposition.

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis.

Science.gov (United States)

Bao, K Q; Gao, J Q; Wang, Z B; Zhang, R Q; Zhang, Z Y; Sugiura, N

2012-01-01

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.

Hydrobiogeochemical interactions in 'anoxic' limestone drains for neutralization of acidic mine drainage

Science.gov (United States)

Robbins, E.I.; Cravotta, C.A.; Savela, C.E.; Nord, G.L.

1999-01-01

Processes affecting neutralization of acidic coal mine drainage were evaluated within 'anoxic' limestone drains (ALDs). Influents had pH???3.5 and dissolved oxygen Al3+ and Fe3+ compounds. Cleavage mounts of calcite and gypsum that were suspended within the ALDs and later examined microscopically showed dissolution features despite coatings by numerous bacteria, biofilms, and Fe-Al-Si precipitates. In the drain exhibiting the greatest flow reduction, Al-hydroxysulfates had accumulated on limestone surfaces and calcite etch points, thus causing the decline in transmissivity and dissolution. Therefore, where Al loadings are high and flow rates are low, a pre-treatment step is indicated to promote Al removal before diverting acidic mine water into alkalinity-producing materials. ?? 1998 Elsevier Science Ltd.

Alternative Fuels Data Center: America's Largest Home Runs on Biodiesel in

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North Carolina America's Largest Home Runs on Biodiesel in North Carolina to someone by E-mail Share Alternative Fuels Data Center: America's Largest Home Runs on Biodiesel in North Carolina on Facebook Tweet about Alternative Fuels Data Center: America's Largest Home Runs on Biodiesel in North

Rapid Return of Nitrogen but not Phosphorus to Ecosystem Nutrition During Decomposition of Quagga Mussel Tissue in Sand, Mud, or Water During Oxic or Anoxic Incubation: Implications for Phytoplankton Bioenergetics.

Science.gov (United States)

Cooney, E. M.; Cuhel, R. L.; Aguilar, C.

2016-02-01

In 2003 Quagga mussels were found to have invaded Lake Michigan. Their presence has changed the structure of the lake both ecologically (benthification) as well as chemically (oligotrophication). They consume large amounts of phytoplankton, which decreases the particulate nitrogen and phosphorous nutrients available to other consumers including zooplankton. As a result, fisheries productivity has decreased nearly 95%. Recently reaching the end of the first life cycle, in death they release a portion of these nutrients back into the freshwater system during decomposition. This work determined amounts of phosphorus and nitrogen nutrient recycling for several relevant sediment-water interface conditions: oxic vs anoxic in water, mud, or sand over a weeklong period. Concentrations of ammonium, soluble reactive phosphorus, and nitrate were used to analyze nutrient release as decomposition took place. In a short time up to 25% of tissue N was released as ammonia, and under oxic conditions in mud or sand, nitrification converted some of the ammonia to nitrate. Unexpectedly, mussels decaying in anoxic conditions released ammonium much more slowly. A slower rate of release in ammonium for the intact body with the shell (burial) was observed when compared to ground mussel tissue (detritivory). Nitrate was removed in anoxic incubations, indicating anaerobic denitrification. Phosphate release was initially higher under anoxic conditions than those decaying aerobically. There was no significant difference in the amount or rate of release of SRP between ground mussel and whole bodied with the shell. The anoxic treatment showed similar patterns of release for both ground mussel and intact body with shell. Most important, phosphate was subsequently removed in all treatments and diffusible nutrient was minimal (<100nM). The results link to nutrient assimilation patterns of deep phytoplankton communities, which can replace nitrate with ammonium as an N source.

Dynamics of nitrification and denitrification in root- oxygenated sediments and adaptation of ammonia-oxidizing bacteria to low-oxygen or anoxic habitats

NARCIS (Netherlands)

Bodelier, P.L.E.; Libochant, J.A.; Blom, C.W.P.M.; Laanbroek, H.J.

1996-01-01

Oxygen-releasing plants may provide aerobic niches in anoxic sediments and soils for ammonia-oxidizing bacteria, The oxygen- releasing, aerenchymatous emergent macrophyte Glycerin maxima had a strong positive effect on numbers and activities of the nitrifying bacteria in its root zone in spring and

Dynamics of nitrification and denitrification in root- oxygenated sediments and adaptation of ammonia-oxidizing bacteria to low-oxygen or anoxic habitats

NARCIS (Netherlands)

Bodelier, P.L.E.; Libochant, J.A.; Blom, C.W.P.M.; Laanbroek, H.J.

1996-01-01

Oxygen-releasing plants may provide aerobic niches in anoxic sediments and soils for ammonia-oxidizing bacteria. The oxygen-releasing, aerenchymatous emergent macrophyte Glyceria maxima had a strong positive effect on numbers and activities of the nitrifying bacteria in its root zone in spring and

Identifying the node spreading influence with largest k-core values

International Nuclear Information System (INIS)

Lin, Jian-Hong; Guo, Qiang; Dong, Wen-Zhao; Tang, Li-Ying; Liu, Jian-Guo

2014-01-01

Identifying the nodes with largest spreading influence of complex networks is one of the most promising domains. By taking into account the neighbors' k-core values, we present an improved neighbors' k-core (INK) method which is the sum of the neighbors' k-core values with a tunable parameter α to evaluate the node spreading influence with largest k-core values. Comparing with the Susceptible–Infected–Recovered (SIR) results for four real networks, the INK method could identify the node spreading influence with largest k-core values more accurately than the ones generated by the degree k, closeness C, betweenness B and coreness centrality method. - Highlights: • We present an improved neighbors' k-core (INK) method to evaluate the node spreading influence with largest k-core values. • The INK method could identify the node spreading influence with largest k-core values more accurately. • Kendall's tau τ of INK method with α=1 are highly identical to rank the node influence

Progress towards the Conventionon Biological Diversity terrestrial2010 and marine 2012 targets forprotected area coverage

DEFF Research Database (Denmark)

Coad, Lauren; Burgess, Neil David; Fish, Lucy

2010-01-01

coverage targets. National protected areas data from the WDPA have been used to measure progress in protected areas coverage at global, regional and national scale. The mean protected area coverage per nation was 12.2% for terrestrial area, and only 5.1% for near-shore marine area. Variation in protected......Protected area coverage targets set by the Convention on Biological Diversity (CBD) for both terrestrial and marine environments provide a major incentive for governments to review and upgrade their protected area systems. Assessing progress towards these targets will form an important component...... of the work of the Xth CBD Conference of Parties meeting to be held in Japan in 2010. The World Database on Protected Areas (WDPA) is the largest assembly of data on the world's terrestrial and marine protected areas and, as such, represents a fundamental tool in tracking progress towards protected area...

Pollution in the Gulf: Monitoring the marine environment

International Nuclear Information System (INIS)

Fowler, S.W.

1993-01-01

More than 2 years after the Gulf conflict, scientists are continuing to keep a close watch on marine pollution stemming from the war. Following the conflict in early 1991, major concern was raised worldwide when an estimated four to eight million barrels of crude oil were directly released into the Persian Gulf from the Sea Island terminal in Kuwait. Such amounts clearly made it the largest oil spill in history. The catastrophe was exacerbated when Kuwaiti oil fields were ignited. The magnitude of the pollution, and the types of toxic contaminants involved, led to a worldwide response through the United Nations system. An inter-agency plan of action was developed quickly. As one of its steps, the co-ordinating agency - the United Nations Environment Programme (UNEP) - asked the IAEA's Marine Environment Laboratory (MEL) in Monaco to help make a preliminary assessment of the situation. The Laboratory's main goal in initial surveys was to map the extent and general degree of the war-related pollution throughout the Gulf. Since the initial surveys were done, IAEA-MEL scientists have been engaged in regional follow-up activities in ongoing attempts to obtain a clearer picture of the oil pollution's effects on the Gulf's marine environment. This article highlights the laboratory's work in the Gulf following the 1991 conflict, within the context of co-operative programmes and projects. 1 fig

Evaluating commercial marine emissions and their role in air quality policy using observations and the CMAQ model

Science.gov (United States)

Ring, Allison M.; Canty, Timothy P.; Anderson, Daniel C.; Vinciguerra, Timothy P.; He, Hao; Goldberg, Daniel L.; Ehrman, Sheryl H.; Dickerson, Russell R.; Salawitch, Ross J.

2018-01-01

We investigate the representation of emissions from the largest (Class 3) commercial marine vessels (c3 Marine) within the Community Multiscale Air Quality (CMAQ) model. In present emissions inventories developed by the United States Environmental Protection Agency (EPA), c3 Marine emissions are divided into off-shore and near-shore files. Off-shore c3 Marine emissions are vertically distributed within the atmospheric column, reflecting stack-height and plume rise. Near-shore c3 Marine emissions, located close to the US shoreline, are erroneously assumed to occur only at the surface. We adjust the near-shore c3 Marine emissions inventory by vertically distributing these emissions to be consistent with the off-shore c3 Marine inventory. Additionally, we remove near-shore c3 Marine emissions that overlap with off-shore c3 Marine emissions within the EPA files. The CMAQ model generally overestimates surface ozone (O3) compared to Air Quality System (AQS) site observations, with the largest discrepancies occurring near coastal waterways. We compare modeled O3 from two CMAQ simulations for June, July, and August (JJA) 2011 to surface O3 observations from AQS sites to examine the efficacy of the c3 Marine emissions improvements. Model results at AQS sites show average maximum 8-hr surface O3 decreases up to ∼6.5 ppb along the Chesapeake Bay, and increases ∼3-4 ppb around Long Island Sound, when the adjusted c3 Marine emissions are used. Along with the c3 Marine emissions adjustments, we reduce on-road mobile NOX emissions by 50%, motivated by work from Anderson et al. 2014, and reduce the lifetime of the alkyl nitrate species group from ∼10 days to ∼1 day based on work by Canty et al. 2015, to develop the ;c3 Science; model scenario. Simulations with these adjustments further improve model representation of the atmosphere. We calculate the ratio of column formaldehyde (HCHO) and tropospheric column nitrogen dioxide (NO2) using observations from the Ozone

Nutrient Removal during Stormwater Aquifer Storage and Recovery in an Anoxic Carbonate Aquifer.

Science.gov (United States)

Vanderzalm, Joanne L; Page, Declan W; Dillon, Peter J; Barry, Karen E; Gonzalez, Dennis

2018-03-01

Stormwater harvesting coupled to managed aquifer recharge (MAR) provides a means to use the often wasted stormwater resource while also providing protection of the natural and built environment. Aquifers can act as a treatment barrier within a multiple-barrier approach to harvest and use urban stormwater. However, it remains challenging to assess the treatment performance of a MAR scheme due to the heterogeneity of aquifers and MAR operations, which in turn influences water treatment processes. This study uses a probabilistic method to evaluate aquifer treatment performance based on the removal of total organic C (TOC), N, and P during MAR with urban stormwater in an anoxic carbonate aquifer. Total organic C, N, and P are represented as stochastic variables and described by probability density functions (PDFs) for the "injectant" and "recovery"; these injectant and recovery PDFs are used to derive a theoretical MAR removal efficiency PDF. Four long-term MAR sites targeting one of two tertiary carbonate aquifers (T1 and T2) were used to describe the nutrient removal efficiencies. Removal of TOC and total N (TN) was dominated by redox processes, with median removal of TOC between 50 and 60% at all sites and TN from 40 to 50% at three sites with no change at the fourth. Total P removal due to filtration and sorption accounted for median removal of 29 to 53%. Thus, the statistical method was able to characterize the capacity of the anoxic carbonate aquifer treatment barrier for nutrient removal, which highlights that aquifers can be an effective long-term natural treatment option for management of water quality, as well as storage of urban stormwater. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Towards a common effort in mapping marine geohazard features in the Mediterranean Sea. An unavoidable tool for the "blue growth" and marine spatial planning.

Science.gov (United States)

Chiocci, F. L.; Gorini, C.; Ercilla, G.; Sakellariou, D.; Casalbore, D.; Ridente, D.

2017-12-01

46,000 km of densely settled coastlines characterise the Mediterranean Sea. The region connects three continents, where the population doubled in the last 20 years, and among which, trade, maritime transports and migratory fluxes have been increasing. Moreover, the Mediterranean is by far the world's largest tourist destination, attracting almost a third of international tourists and generating more than a quarter of tourism-related revenues worldwide. The Mediterranean area lays in a plate boundary zone highly active in terms of seismicity, volcanism and submarine geological processes that over recent time have repeatedly demonstrated to be able to generate catastrophic events.. As an example 98 tsunamis where recorded in the Mediterranean on historical times (on average one every century). This census do not encompasses small events, such as minor tsunamis generated by submarine landslides that can produce serious damage in the near field. In Stromboli volcanic island (Southern Tyrrhenian Sea) for instance, the frequency of such events accounts for 5 events over the last century Mapping the seafloor for geohazard assessment becomes, therefore, especially important for the sustainable development of the marine and coastal areas both economically and socially. The increasing amount of high resolution seafloor mapping data allows defining geohazard features such as volcanic vents, active faults, submarine landslide, canyon head migrating bedforms fluid expulsion structure with a detail able to highlight even locally dangerous situations. If the marine geoscience community will be able to build common standards to interpret and cartographically represent the marine geohazard features private industries and public agencies will benefit of an unvaluable tool which will help in better exploit the marine resource and/or preserve the marine and coastal environment. This contribution will present spectacular examples of marine geohazards from the Mediterranean Seas; the

Mechanistic investigations of Se(VI) treatment in anoxic groundwater using granular iron and organic carbon: An EXAFS study

International Nuclear Information System (INIS)

Gibson, Blair D.; Blowes, David W.; Lindsay, Matthew B.J.; Ptacek, Carol J.

2012-01-01

Highlights: ► We investigate treatment of aqueous Se(VI) under anoxic conditions. ► We utilize granular Fe 0 and organic carbon to promote Se(VI) removal. ► We characterize Se speciation using X-ray absorption spectroscopy. ► Granular Fe 0 promotes removal of Se(VI) by reduction to Se(0). ► Organic carbon promotes removal through sorption processes without reduction. - Abstract: The removal of aqueous Se(VI) from a simulated groundwater by granular iron (GI), organic carbon (OC), and a mixture of these reactive materials (GI–OC) was evaluated in laboratory batch experiments. The experiments were performed under anoxic conditions to simulate subsurface treatment. A total reaction time of 120 h (5 d) was chosen to investigate the rapid changes in speciation occurring over reaction times that are reasonable for permeable reactive barrier (PRB) systems. After 120 h, concentrations of Se decreased by >90% in the GI system, 15% in the OC system and 35% in the GI–OC mixture. Analysis of the materials after contact with Se using synchrotron-radiation based X-ray absorption spectroscopy (XAS) indicated the presence of Se(IV) and Se(0) on the margins of GI grains after 6 h with evidence of Se-O and Se-Se bonding, whereas Se(VI) was not observed. After 72 h, Se(0) was the only form of Se present in the GI experiments. In the OC batches, the XAS analysis indicated binding consistent with sorption of aqueous Se(VI) onto the OC with only minor reduction to Se(IV) and Se(0) after 120 h. Selenium XAS spectra collected for the GI–OC mixture were consistent with spectra for Se(IV) and Se(0) on both the margins of GI grains and OC particles, suggesting that the presence of dissolved Fe may have mediated the reduction of sorbed Se(VI). The results suggest that the application of granular Fe is effective at inducing aqueous Se removal in anoxic conditions through reductive precipitation processes.

Application of a multimolecular marker approach to fingerprint petroleum pollution in the marine environment

International Nuclear Information System (INIS)

Barakat, Assem O.; Mostafa, Alaa R.; Rullkoetter, Juergen; Hegazi, Abdel Rahman

1999-01-01

In an attempt to investigate the suitability of a multibiological marker approach for defining the origin of petroleum pollution in marine systems, the aliphatic hydrocarbon composition of tar ball samples collected from the beaches of a small island impacted by heavy tar loads were determined by gas chromatography and gas chromatography/mass spectrometry. The tar ball samples, as collected, were at low stages of biodegradation and had diverse physical appearance. The majority of the samples (as many as 7 of the 10) appeared to be heavy fuel oils - possibly Bunker C. The GC traces for the other three tar balls, however, indicated that they were crude oils probably from tanker ballast washings or other non-point sources like the oil entering from the adjacent North Mediterranean. The biomarkers for the sterane and hopane series in these samples, however, had remained unaffected by weathering, and their distributions revealed significant differences among the samples suggesting multiple sources of the tar balls. The tar ball samples could be genetically subdivided into four groups on the basis of their biomarker fingerprints. A marine carbonate or evaporite, hypersaline, anoxic depositional environment of the petroleum source rock for Type I residues could be inferred from the even-carbon-number predominance of n-alkanes, the high relative abundance of gammacerane and the predominance of C 35 relative to C 34 17α(H)-homohopanes. Higher plant contribution and a deltaic environment of source rock deposition could be concluded for Type II residues from the high concentrations of oleanane and diasteranes. On the other hand, Type III residues possessed geochemical characteristics consistent with a normal marine carbonate or evaporite source depositional environment under normal saline, reducing conditions. Finally, type IV residues had biomarker signatures intermediate between Types II and III. (Author)

Increased carbon uptake in marine sediment enabled by naturally occurring electrical conductors

Science.gov (United States)

Nielsen, M. E.; Cahoon, D. P.; Girguis, P. R.

2011-12-01

Reduction-oxidation (redox) gradients are common across marine sediment-water interfaces and result from microbially-mediated reactions such as the oxidation of organic matter coupled to reduction of electron acceptors. Most microbes living in sediments do not have direct access to oxygen in their immediate environment, however it has recently been shown that sulfide-oxidizing microbes may employ extracellular electron transfer (EET) to couple the oxidation of sulfide in the anoxic zone to reduction of oxygen at the sediment-water interface located several centimeters away. However, no mechanisms for this observed phenomenon have been validated. Accordingly, we tested the hypothesis that conductive minerals in marine sediment (specifically pyrite) can couple spatially separated redox reactions such as anaerobic respiration and oxygen reduction. Marine sediment was amended with naturally occurring pyrite in varying concentrations (0, 2, 10 and 50 weight-percent) and then incubated with 10 μM 13C-labeled acetate. After six hours, the treatments with the greatest amount of added pyrite showed the greatest incorporation of acetate from the labeled pool. The fraction of labeled acetate incorporation more than doubled in the 10 and 50 weight-percent treatments compared to the control sediment. We also designed a circuit to investigate the electrical conductivity of the sediment treatments as a function of added pyrite. A potentiostat was used to establish a known voltage across a sediment column and current was measured. Resistance (the inverse of conductance) was calculated from a linear fit of current data over a range of voltages ranging from 0.5 to 1.0 V. The treatments with added pyrite had lower resistance than background sediment, with the lowest resistance corresponding to the 50% pyrite treatment. We also examined the effect of varying pyrite content on microbial community composition using massively parallel 16S rRNA sequencing. Microbial community analyses

CERN tests largest superconducting solenoid magnet

CERN Multimedia

2006-01-01

"CERN's Compacts Muon Solenoid (CMS) - the world's largest superconducting solenoid magnet - has reached full field in testing. The instrument is part of the proton-proton Large Hadron Collider (LHC) project, located in a giant subterranean chamber at Cessy on the Franco-Swiss border." (1 page)

Marine denitrification rates determined from a global 3-D inverse model

Directory of Open Access Journals (Sweden)

T. DeVries

2013-04-01

Full Text Available A major impediment to understanding long-term changes in the marine nitrogen (N cycle is the persistent uncertainty about the rates, distribution, and sensitivity of its largest fluxes in the modern ocean. We use a global ocean circulation model to obtain the first 3-D estimate of marine denitrification rates that is maximally consistent with available observations of nitrate deficits and the nitrogen isotopic ratio of oceanic nitrate. We find a global rate of marine denitrification in suboxic waters and sediments of 120–240 Tg N yr−1, which is lower than many other recent estimates. The difference stems from the ability to represent the 3-D spatial structure of suboxic zones, where denitrification rates of 50–77 Tg N yr−1 result in up to 50% depletion of nitrate. This depletion reduces the effect of local isotopic enrichment on the rest of the ocean, allowing the N isotope ratio of oceanic nitrate to be achieved with a sedimentary denitrification rate about 1.3–2.3 times that of suboxic zones. This balance of N losses between sediments and suboxic zones is shown to obey a simple relationship between isotope fractionation and the degree of nitrate consumption in the core of the suboxic zones. The global denitrification rates derived here suggest that the marine nitrogen budget is likely close to balanced.

Phylogeography of the sponge Suberites diversicolor in Indonesia: insights into the evolution of marine lake populations.

Science.gov (United States)

Becking, Leontine E; Erpenbeck, Dirk; Peijnenburg, Katja T C A; de Voogd, Nicole J

2013-01-01

The existence of multiple independently derived populations in landlocked marine lakes provides an opportunity for fundamental research into the role of isolation in population divergence and speciation in marine taxa. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea and could be regarded as the marine equivalents of terrestrial islands. The sponge Suberites diversicolor (Porifera: Demospongiae: Suberitidae) is typical of marine lake habitats in the Indo-Australian Archipelago. Four molecular markers (two mitochondrial and two nuclear) were employed to study genetic structure of populations within and between marine lakes in Indonesia and three coastal locations in Indonesia, Singapore and Australia. Within populations of S. diversicolor two strongly divergent lineages (A & B) (COI: p = 0.4% and ITS: p = 7.3%) were found, that may constitute cryptic species. Lineage A only occurred in Kakaban lake (East Kalimantan), while lineage B was present in all sampled populations. Within lineage B, we found low levels of genetic diversity in lakes, though there was spatial genetic population structuring. The Australian population is genetically differentiated from the Indonesian populations. Within Indonesia we did not record an East-West barrier, which has frequently been reported for other marine invertebrates. Kakaban lake is the largest and most isolated marine lake in Indonesia and contains the highest genetic diversity with genetic variants not observed elsewhere. Kakaban lake may be an area where multiple putative refugia populations have come into secondary contact, resulting in high levels of genetic diversity and a high number of endemic species.

Phylogeography of the Sponge Suberites diversicolor in Indonesia: Insights into the Evolution of Marine Lake Populations

Science.gov (United States)

Becking, Leontine E.; Erpenbeck, Dirk; Peijnenburg, Katja T. C. A.; de Voogd, Nicole J.

2013-01-01

The existence of multiple independently derived populations in landlocked marine lakes provides an opportunity for fundamental research into the role of isolation in population divergence and speciation in marine taxa. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea and could be regarded as the marine equivalents of terrestrial islands. The sponge Suberites diversicolor (Porifera: Demospongiae: Suberitidae) is typical of marine lake habitats in the Indo-Australian Archipelago. Four molecular markers (two mitochondrial and two nuclear) were employed to study genetic structure of populations within and between marine lakes in Indonesia and three coastal locations in Indonesia, Singapore and Australia. Within populations of S. diversicolor two strongly divergent lineages (A & B) (COI: p = 0.4% and ITS: p = 7.3%) were found, that may constitute cryptic species. Lineage A only occurred in Kakaban lake (East Kalimantan), while lineage B was present in all sampled populations. Within lineage B, we found low levels of genetic diversity in lakes, though there was spatial genetic population structuring. The Australian population is genetically differentiated from the Indonesian populations. Within Indonesia we did not record an East-West barrier, which has frequently been reported for other marine invertebrates. Kakaban lake is the largest and most isolated marine lake in Indonesia and contains the highest genetic diversity with genetic variants not observed elsewhere. Kakaban lake may be an area where multiple putative refugia populations have come into secondary contact, resulting in high levels of genetic diversity and a high number of endemic species. PMID:24098416

The long-term effect of hydrogen on the UO2 spent fuel stability under anoxic conditions: Findings from the Cigar Lake Natural Analogue study

International Nuclear Information System (INIS)

Bruno, Jordi; Spahiu, Kastriot

2014-01-01

Highlights: • We have reviewed current information on the effect of hydrogen in UO 2 spent fuel. • We explored the radiolytic models generated in the Cigar Lake project. • The Cigar Lake data supports that H 2 reduces alpha radiolysis oxidants. • The results indicate the hydrogen effect is present after 100.000 years deposition. - Abstract: The present paradigm on UO 2 spent fuel stability under anoxic conditions assumes that the potential oxidative alteration of the matrix is suppressed in the presence of the hydrogen generated by the anoxic corrosion of iron by water. The observations from the Cigar Lake Natural Analogue project indicated the long-term stability of the uraninite ore under anoxic conditions and with substantial hydrogen generation. The radiolytic models developed in the analogue project have been used to test some of the hypothesis concerning the activation of hydrogen on the uranium(IV) oxide surface. Suggestions to pathways of radiolytic oxidant consumption by other processes than uranium dioxide or sulphide oxidation are presented. The stability of the ore body for billions of year indicates the presence of processes which neutralise radiolytic oxidants and one major factor may be the presence of dissolved hydrogen in the groundwaters contacting the ore body. The results from this test would indicate that hydrogen is activated on the surface of the Cigar Lake uraninites by alpha radiation consuming the generated radiolytic oxidants

POSSIBLE METHODS FOR PREVENTING PLASTIC WASTE FROM ENTERING THE MARINE ENVIRONMENT

OpenAIRE

David, Minodora-Florentina; Burdukovska, Valentina; Heng, Chen

2013-01-01

The widespread use of plastic has become a huge threat for the marine environment. With problems such as the oceanic garbage patches increasing more and more in scale, the focus is set on how could plastic waste be prevented from entering the oceans and adversely affecting the wildlife. Since the largest accumulation of plastic waste is found in the North Pacific Gyre, we have looked at the surrounding countries with the highest waste generation. By using the pyramid of waste as a starting po...

Dynamic of sulphate-reducing microorganisms in petroleum-contaminated marine sediments inhabited by the polychaete Hediste diversicolor.

Science.gov (United States)

Stauffert, Magalie; Cravo-Laureau, Cristiana; Duran, Robert

2015-10-01

The behaviour of sulphate-reducing microbial community was investigated at the oxic-anoxic interface (0-2 cm) of marine sediments when submitted to oil and enhanced bioturbation activities by the addition of Hediste diversicolor. Although total hydrocarbon removal was not improved by the addition of H. diversicolor, terminal restriction fragment length polymorphism (T-RFLP) analyses based on dsrAB (dissimilatory sulphite reductase) genes and transcripts showed different patterns according to the presence of H. diversicolor which favoured the abundance of dsrB genes during the early stages of incubation. Complementary DNA (cDNA) dsrAB libraries revealed that in presence of H. diversicolor, most dsrAB sequences belonged to hydrocarbonoclastic Desulfobacteraceae, suggesting that sulphate-reducing microorganisms (SRMs) may play an active role in hydrocarbon biodegradation in sediments where the reworking activity is enhanced. Furthermore, the presence of dsrAB sequences related to sequences found associated to environments with high dinitrogen fixation activity suggested potential N2 fixation by SRMs in bioturbated-polluted sediments.

Microbial pathways for the mobilization of mercury as Hg(O) in anoxic subsurface environments

Energy Technology Data Exchange (ETDEWEB)

Barkay, Tamar

2005-06-01

The goal of our project which was initiated in June 2005 is focused on the presence of merA in microbial communities of anoxic environments and the effect of anaerobic respiratory pathways on MR expression and activities. The following progress has been made to date: PCR primers were designed to span the known phylogenetic range of merA genes of Gram-negative bacteria. In control experiments, these primers successfully amplified a 288 bp region at the 3? end of previously characterized merA genes from Shewanella putrefaciens pMERPH, Acidithiobacillus ferrooxidans, Pseudomonas stutzeri pPB, Tn5041, Pseudomonas sp. K-62, and Serratia marcescens pDU1358.

Analysis of Human Standing Balance by Largest Lyapunov Exponent

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Kun Liu

2015-01-01

Full Text Available The purpose of this research is to analyse the relationship between nonlinear dynamic character and individuals’ standing balance by the largest Lyapunov exponent, which is regarded as a metric for assessing standing balance. According to previous study, the largest Lyapunov exponent from centre of pressure time series could not well quantify the human balance ability. In this research, two improvements were made. Firstly, an external stimulus was applied to feet in the form of continuous horizontal sinusoidal motion by a moving platform. Secondly, a multiaccelerometer subsystem was adopted. Twenty healthy volunteers participated in this experiment. A new metric, coordinated largest Lyapunov exponent was proposed, which reflected the relationship of body segments by integrating multidimensional largest Lyapunov exponent values. By using this metric in actual standing performance under sinusoidal stimulus, an obvious relationship between the new metric and the actual balance ability was found in the majority of the subjects. These results show that the sinusoidal stimulus can make human balance characteristics more obvious, which is beneficial to assess balance, and balance is determined by the ability of coordinating all body segments.

Anoxic and Oxic Oxidation of Rocks Containing Fe(II)Mg-Silicates and Fe(II)-Monosulfides as Source of Fe(III)-Minerals and Hydrogen. Geobiotropy.

Science.gov (United States)

Bassez, Marie-Paule

2017-12-01

In this article, anoxic and oxic hydrolyses of rocks containing Fe (II) Mg-silicates and Fe (II)-monosulfides are analyzed at 25 °C and 250-350 °C. A table of the products is drawn. It is shown that magnetite and hydrogen can be produced during low-temperature (25 °C) anoxic hydrolysis/oxidation of ferrous silicates and during high-temperature (250 °C) anoxic hydrolysis/oxidation of ferrous monosulfides. The high-T (350 °C) anoxic hydrolysis of ferrous silicates leads mainly to ferric oxides/hydroxides such as the hydroxide ferric trihydroxide, the oxide hydroxide goethite/lepidocrocite and the oxide hematite, and to Fe(III)-phyllosilicates. Magnetite is not a primary product. While the low-T (25 °C) anoxic hydrolysis of ferrous monosulfides leads to pyrite. Thermodynamic functions are calculated for elementary reactions of hydrolysis and carbonation of olivine and pyroxene and E-pH diagrams are analyzed. It is shown that the hydrolysis of the iron endmember is endothermic and can proceed within the exothermic hydrolysis of the magnesium endmember and also within the exothermic reactions of carbonations. The distinction between three products of the iron hydrolysis, magnetite, goethite and hematite is determined with E-pH diagrams. The hydrolysis/oxidation of the sulfides mackinawite/troilite/pyrrhotite is highly endothermic but can proceed within the heat produced by the exothermic hydrolyses and carbonations of ferromagnesian silicates and also by other sources such as magma, hydrothermal sources, impacts. These theoretical results are confirmed by the products observed in several related laboratory experiments. The case of radiolyzed water is studied. It is shown that magnetite and ferric oxides/hydroxides such as ferric trihydroxide, goethite/lepidocrocite and hematite are formed in oxic hydrolysis of ferromagnesian silicates at 25 °C and 350 °C. Oxic oxidation of ferrous monosulfides at 25 °C leads mainly to pyrite and ferric oxides/hydroxides such as

Role of soil geochemical and microbiological components on selenium behaviour in oxic and anoxic conditions

International Nuclear Information System (INIS)

Darcheville, O.

2008-09-01

Selenium (Se) is naturally present in the environment. Se is essential for living organisms at trace concentrations, but it becomes rapidly toxic with their increases. The 79 Se radioactive isotopes of Se, is found in nuclear wastes that may be buried in deep geological formations. In soil, Se exists in many forms and its mobility is affected by the redox potential and microbial activity. Very few studies have focused on Se behaviour at trace concentration. We have tried to distinguish the major abiotic geochemical and microbiological processes involved in the fate of trace selenite (Se(IV)) in a soil. The study was based on batch incubation in oxic or anoxic conditions of slurry suspension artificially contaminated with Se (IV) to 0.4 mg Se.kg -1 dry soil. The incubation involved sterilized and non-sterile soil samples with or without organic amendment to stimulate microbial activities. For each incubation, we followed the distribution of Se between solid, liquid and gaseous phases as well as the geochemical evolution of the solution, the composition of the atmosphere gas bottles and the soil microflora. The results showed that Se was relatively few mobile in the soil studied. Geochemical processes played a major role in controlling the Se mobility. Over time, some abiotic transformations in the solid phase contributed to increase the Se immobilisation. The microbiological processes contributed to this increase in the solid phase. Moreover, in oxic as in anoxic conditions, some microbial processes were responsible, to a lesser extent, for a dispersion of Se in the atmosphere by the production of volatile compounds. (author)

Copper corrosion experiments under anoxic conditions

Energy Technology Data Exchange (ETDEWEB)

Ollila, Kaija [VTT Technical Research Centre of Finland, Espoo (Finland)

2013-06-15

This report gives results from the corrosion experiments with copper under anoxic conditions. The objective was to study whether hydrogen-evolving corrosion reaction could occur. Copper foil samples were exposed in deaerated deionized water in Erlenmeyer flasks in the glove box with inert atmosphere. Four corrosion experiments (Cu1, Cu2, Cu3 and Cu4) were started, as well as a reference test standing in air. Cu1 and Cu2 had gas tight seals, whereas Cu3 and Cu4 had palladium foils as hydrogen permeable enclosure. The test vessels were stored during the experiments in a closed stainless steel vessel to protect them from the trace oxygen of the gas atmosphere and light. After the reaction time of three and a half years, there were no visible changes in the copper surfaces in any of the tests in the glove box, in contrast the Cu surfaces looked shiny and unaltered. The Cu3 test was terminated after the reaction time of 746 days. The analysis of the Pd-membrane showed the presence of H2 in the test system. If the measured amount of 7.2{center_dot}10{sup 5} mol H{sub 2} was the result of formation of Cu{sub 2}O this would correspond to a 200 nm thick corrosion layer. This was not in agreement with the measured layer thickness with SIMS, which was 6{+-}1 nm. A clear weight loss observed for the Cu3 test vessel throughout the test period suggests the evaporation of water through the epoxy sealing to the closed steel vessel. If this occurred, the anaerobic corrosion of steel surface in humid oxygen-free atmosphere could be a source of hydrogen. A similar weight loss was not observed for the parallel test (Cu4). The reference test standing in air showed visible development of corrosion products.

Occurrence of Priming in the Degradation of Lignocellulose in Marine Sediments.

Science.gov (United States)

Gontikaki, Evangelia; Thornton, Barry; Cornulier, Thomas; Witte, Ursula

2015-01-01

More than 50% of terrestrially-derived organic carbon (terrOC) flux from the continents to the ocean is remineralised in the coastal zone despite its perceived high refractivity. The efficient degradation of terrOC in the marine environment could be fuelled by labile marine-derived material, a phenomenon known as "priming effect", but experimental data to confirm this mechanism are lacking. We tested this hypothesis by treating coastal sediments with 13C-lignocellulose, as a proxy for terrOC, with and without addition of unlabelled diatom detritus that served as the priming inducer. The occurrence of priming was assessed by the difference in lignocellulose mineralisation between diatom-amended treatments and controls in aerobic sediment slurries. Priming of lignocellulose degradation was observed only at the initial stages of the experiment (day 7) and coincided with overall high microbial activity as exemplified by total CO2 production. Lignocellulose mineralisation did not differ consistently between diatom treatments and control for the remaining experimental time (days 14-28). Based on this pattern, we hypothesize that the faster initiation of lignocellulose mineralisation in diatom-amended treatments is attributed to the decomposition of accessible polysaccharide components within the lignocellulose complex by activated diatom degraders. The fact that diatom-degraders contributed to lignocellulose degradation was also supported by the different patterns in 13C-enrichment of phospholipid fatty acids between treatments. Although we did not observe differences between treatments in the total quantity of respired lignocellulose at the end of the experiment, differences in timing could be important in natural ecosystems where the amount of time that a certain compound is subject to aerobic degradation before burial to deeper anoxic sediments may be limited.

Degradation of typical N-nitrosodimethylamine (NDMA) precursors and its formation potential in anoxic-aerobic (AO) activated sludge system.

Science.gov (United States)

Wang, Lin; Li, Yongmei; He, Guodong

2014-01-01

N-nitrosodimethylamine (NDMA) is an emerging disinfection byproduct. Removal of its potential precursors is considered as an effective method to control NDMA. In this study, four typical NDMA precursors (dimethylamine (DMA), trimethylamine (TMA), dimethylformamide (DMFA) and dimethylaminobenzene (DMAB)) were selected, and their removal capacities by activated sludge were investigated. Batch experiments indicated that removal of NDMA precursors was better under aerobic condition than anoxic condition; and their specific degradation rates follow the order of DMA > TMA > DMFA > DMAB. In anoxic-aerobic (AO) activated sludge system, the optimal hydraulic retention time and sludge retention time were 10 h and 20 d, respectively, for the removal of both NDMA precursors (four selected NDMA precursors and NDMA formation potential (NDMA FP)) and nutrients. Our results also suggested that there was a positive correlation between NDMA FP and dissolved organic nitrogen (DON) in wastewater. The removal efficiency of NDMA FP was in the range of 46.8-72.5% in the four surveyed wastewater treatment plants except the one which adopted chemically enhanced primary process. The results revealed that the AO system had the advantage of removing NDMA FP. Our results are helpful for the knowledge of the removals of NDMA precursors during activated sludge treatment processes.

Energetic Constraints on H-2-Dependent Terminal Electron Accepting Processes in Anoxic Environments

DEFF Research Database (Denmark)

Heimann, Axel Colin; Jakobsen, Rasmus; Blodau, C.

2010-01-01

and sulfate reduction are under direct thermodynamic control in soils and sediments and generally approach theoretical minimum energy thresholds. If H-2 concentrations are lowered by thermodynamically more potent TEAPs, these processes are inhibited. This principle is also valid for TEAPS providing more free......Microbially mediated terminal electron accepting processes (TEAPs) to a large extent control the fate of redox reactive elements and associated reactions in anoxic soils, sediments, and aquifers. This review focuses on thermodynamic controls and regulation of H-2-dependent TEAPs, case studies...... illustrating this concept and the quantitative description of thermodynamic controls in modeling. Other electron transfer processes are considered where appropriate. The work reviewed shows that thermodynamics and microbial kinetics are connected near thermodynamic equilibrium. Free energy thresholds...

Half saturation constants for nitrate and nitrite by in-sewer anoxic transformations of wastewater organic matter

DEFF Research Database (Denmark)

Abdul-Talib, Suhaimi; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

2001-01-01

 significant breakthrough and progress have been made in the study of the kinetics of microbial transformation in sewers under aerobic and under changing aerobic/anaerobic conditions. Fundamental knowledge on anoxic kinetics of wastewater is still lacking, so it is not now possible to apply...... an integrated approach to municipal wastewater treatment incorporating sewer networks as a bio-chemical reactor. This paper presents the results of studies on determining half saturation constants for nitrate, KNO3, and nitrite, KNO2, in raw wastewater. The average values of KNO3 and KNO2, determined from...

The influence of ganglioside on the blood gas analysis and serum inflammatory cytokines in newborns with anoxic ischemic encephalopathy

Directory of Open Access Journals (Sweden)

Xiao-Jing Li

2017-04-01

Full Text Available Objective: To observe the influence of ganglioside on the blood gas analysis and serum levels of inflammatory cytokines in newborns with anoxic ischemic encephalopathy. Method: A total of 100 newborns with anoxic ischemic encephalopathy in our hospital were selected and randomly divided into 2 groups: the control group and the observation group. Conventional oxygen inhalation, reducing intracranial pressure, controlling eclampsia and neurotrophic drug treatment were given to the observation group. Treatment of ganglioside was given to the control group on the basis of observation group. Blood gas analysis and serum levels of inflammatory cytokines were detected before treatment (T0, 3 d after treatment (T1, and 7 d after treatment (T2. Result: (1 The comparison of pH, PaO2, PaCO2, SaO2 in the two groups in T0 was not statistically significant. The comparison of pH, PaO2, PaCO2, SaO2 in T0, T1, T2 was considered to be statistically significant. Among these, the result of comparision of pH, PaO2, SaO2: T0＜T1＜T2. comparision of PaCO2: T0＞T1＞T2. The pH, PaO2, SaO2 in observation group were higher, PaCO2 in observation group was lower compared with that in control group in T1 and T2. The difference was considered to be statistically significant. (2 The comparision of IL-2, IL-6, hs-CRP, TNF-α in the two groups in T0 was not statistically significant. IL-2 in the observation in T1 and T2 was higher than that in the control group, IL-6, hs-CRP, TNF-α in the observation in T1 and T2 was lower than that in the control group. The difference was considered to be statistically significant. Conclusion: Ganglioside can improve blood gas analysis indexes, decrease the serum inflammatory cytokines in newborns with anoxic ischemic encephalopathy.

Cumulative effects of planned industrial development and climate change on marine ecosystems

Directory of Open Access Journals (Sweden)

Cathryn Clarke Murray

2015-07-01

Full Text Available With increasing human population, large scale climate changes, and the interaction of multiple stressors, understanding cumulative effects on marine ecosystems is increasingly important. Two major drivers of change in coastal and marine ecosystems are industrial developments with acute impacts on local ecosystems, and global climate change stressors with widespread impacts. We conducted a cumulative effects mapping analysis of the marine waters of British Columbia, Canada, under different scenarios: climate change and planned developments. At the coast-wide scale, climate change drove the largest change in cumulative effects with both widespread impacts and high vulnerability scores. Where the impacts of planned developments occur, planned industrial and pipeline activities had high cumulative effects, but the footprint of these effects was comparatively localized. Nearshore habitats were at greatest risk from planned industrial and pipeline activities; in particular, the impacts of planned pipelines on rocky intertidal habitats were predicted to cause the highest change in cumulative effects. This method of incorporating planned industrial development in cumulative effects mapping allows explicit comparison of different scenarios with the potential to be used in environmental impact assessments at various scales. Its use allows resource managers to consider cumulative effect hotspots when making decisions regarding industrial developments and avoid unacceptable cumulative effects. Management needs to consider both global and local stressors in managing marine ecosystems for the protection of biodiversity and the provisioning of ecosystem services.

Diversity and Inclusion in Conservation: A Proposal for a Marine Diversity Network

Directory of Open Access Journals (Sweden)

Nicola S. Smith

2017-08-01

Full Text Available Low diversity among scientists and practitioners is rampant in conservation. Currently, conservation professionals do not reflect the same diversity of perspectives and experiences of the world as the communities who bear the largest burden for implementing—or adverse consequences for failing to implement—conservation action. Acknowledging and describing the problem is important. But policies and programmes must also be put in place to correct it. Here, we highlight some measurable benefits of workforce diversity, and give an overview of some of the barriers to inclusion in marine conservation that help perpetuate low workforce diversity. Importantly, we underscore actions that both individuals and groups can take to alleviate such barriers. In particular, we describe the establishment of an online Marine Diversity Network, which conference participants proposed during a focus group meeting at the 4th International Marine Conservation Congress. The network will serve to bring together people from across the globe, from a variety of backgrounds, and from all career stages, to share knowledge, experiences and ideas, to provide and receive mentorship in marine conservation, and to forge new collaborations. Removing barriers to diverse participation requires coordinated, mindful actions by individuals and organizations. We hope that the proposed network and other actions presented in this paper find widespread support, and that they might serve both as inspiration and guide to other groups concerned with increasing diversity and inclusivity.

The cost and feasibility of marine coastal restoration.

Science.gov (United States)

Bayraktarov, Elisa; Saunders, Megan I; Abdullah, Sabah; Mills, Morena; Beher, Jutta; Possingham, Hugh P; Mumby, Peter J; Lovelock, Catherine E

2016-06-01

Land-use change in the coastal zone has led to worldwide degradation of marine coastal ecosystems and a loss of the goods and services they provide. Restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed and is critical for habitats where natural recovery is hindered. Uncertainties about restoration cost and feasibility can impede decisions on whether, what, how, where, and how much to restore. Here, we perform a synthesis of 235 studies with 954 observations from restoration or rehabilitation projects of coral reefs, seagrass, mangroves, salt-marshes, and oyster reefs worldwide, and evaluate cost, survival of restored organisms, project duration, area, and techniques applied. Findings showed that while the median and average reported costs for restoration of one hectare of marine coastal habitat were around US$80000 (2010) and US$1600000 (2010), respectively, the real total costs (median) are likely to be two to four times higher. Coral reefs and seagrass were among the most expensive ecosystems to restore. Mangrove restoration projects were typically the largest and the least expensive per hectare. Most marine coastal restoration projects were conducted in Australia, Europe, and USA, while total restoration costs were significantly (up to 30 times) cheaper in countries with developing economies. Community- or volunteer-based marine restoration projects usually have lower costs. Median survival of restored marine and coastal organisms, often assessed only within the first one to two years after restoration, was highest for saltmarshes (64.8%) and coral reefs (64.5%) and lowest for seagrass (38.0%). However, success rates reported in the scientific literature could be biased towards publishing successes rather than failures. The majority of restoration projects were short-lived and seldom reported monitoring costs. Restoration success depended primarily on the ecosystem, site selection, and techniques

Uranium(VI) Reduction by Nanoscale Zerovalent Iron in Anoxic Batch Systems

International Nuclear Information System (INIS)

Yan, Sen; Hua, Bin; Bao, Zhengyu; Yang, John; Liu, Chongxuan; Deng, Baolin

2010-01-01

This study investigated the influences of pH, bicarbonate, and calcium on U(VI) adsorption and reduction by synthetic nanosize zero valent iron (nano Fe 0 ) particles under an anoxic condition. The results showed that about 87.1%, 82.7% and 78.3% of U(VI) could be reduced within 96 hours in the presence of 10 mM bicarbonate at pHs 6.92, 8.03 and 9.03, respectively. The rates of U(VI) reduction and adsorption by nano Fe 0 , however, varied significantly with increasing pH and concentrations of bicarbonate and/or calcium. Solid phase analysis by X-ray photoelectron spectroscopy confirmed the formation of UO 2 and iron (hydr)oxides as a result of the redox interactions between adsorbed U(VI) and nano Fe 0 . This study highlights the potential important role of groundwater chemical composition in controlling the rates of U(VI) reductive immobilization using nano Fe 0 in subsurface environments.

Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)

DEFF Research Database (Denmark)

Stecyk, Jonathan A.W.; Jensen, Nini Skovgaard; Nilsson, Göran E.

2010-01-01

Systemic vascular resistance (Rsys) of freshwater turtles increases substantially during anoxia, but the underlying mechanisms are not fully understood. We investigated whether hydrogen sulfide (H2S), an endogenously produced metabolite believed to be an O2 sensor/transducer of vasomotor tone......, contributes to the increased Rsys of anoxic red-eared slider turtles (Trachemys scripta). Vascular infusion of the H2S donor NaHS in anesthetized turtles at 21°C and fully recovered normoxic turtles at 5°C and 21°C revealed H2S to be a potent vasoconstrictor of the systemic circulation. Likewise, wire...... myography of isolated turtle mesenteric and pulmonary arteries demonstrated H2S to mediate an anoxia-induced constriction. Intriguingly, however, NaHS did not exert vasoconstrictory effects during anoxia (6 h at 21°C; 14 days at 5°C) when plasma H2S concentration, estimated from the colorimetric measurement...

Nitrogen cycle feedbacks as a control on euxinia in the mid-Proterozoic ocean

DEFF Research Database (Denmark)

Boyle, R. A.; Clark, J. R.; Poulton, Simon W.

2013-01-01

Geochemical evidence invokes anoxic deep oceans until the terminal Neoproterozoic similar to 0.55 Ma, despite oxygenation of Earth's atmosphere nearly 2 Gyr earlier. Marine sediments from the intervening period suggest predominantly ferruginous (anoxic Fe(II)-rich) waters, interspersed with euxinia...... (anoxic H2S-rich conditions) along productive continental margins. Today, sustained biotic H2S production requires NO3- depletion because denitrifiers outcompete sulphate reducers. Thus, euxinia is rare, only occurring concurrently with (steady state) organic carbon availability when N-2-fixers dominate...... the production in the photic zone. Here we use a simple box model of a generic Proterozoic coastal upwelling zone to show how these feedbacks caused the mid-Proterozoic ocean to exhibit a spatial/temporal separation between two states: photic zone NO3- with denitrification in lower anoxic waters, and N-2...

Linking metatranscriptomic to bioremediation processes of oil contaminated marine sediments

Science.gov (United States)

Cuny, P.; Atkinson, A.; Léa, S.; Guasco, S.; Jezequel, R.; Armougom, F.; Michotey, V.; Bonin, P.; Militon, C.

2016-02-01

Oil-derived hydrocarbons are one major source of pollution of marine ecosystems. In coastal marine areas they tend to accumulate in the sediment where they can impact the benthic communities. Oil hydrocarbons biodegradation by microorganisms is known to be one of the prevalent processes acting in the removal of these contaminants from sediments. The redox oscillation regimes generated by bioturbation, and the efficiency of metabolic coupling between functional groups associated to these specific redox regimes, are probably determinant factors controlling hydrocarbon biodegradation. Metatranscriptomic analysis appears like a promising approach to shed new light on the metabolic processes involved in the response of microbial communities to oil contamination in such oxic/anoxic oscillating environments. In the framework of the DECAPAGE project (ANR CESA-2011-006 01), funded by the French National Agency for Research, the metatranscriptomes (RNA-seq) of oil contaminated or not (Ural blend crude oil, 5 000 ppm) and bioturbated or not (addition of the common burrowing organism Hediste diversicolor, 1000 ind/m2) mudflat sediments, incubated in microcosms during 4 months at 19±1°C, were compared. The analysis of active microbial communities by SSU rRNA barcoding shows that the main observable changes are due to the presence of H. diversicolor. On the contrary, oil addition is the main factor explaining the observed changes in the genes expression patterns with 1949 genes specifically up or down-regulated (which is the case of only 245 genes when only H. diversicolor worms are added). In particular, the oil contamination leads to a marked overexpression (i) of benzyl- and alkylsuccinate synthase genes (ass and bss) that are involved in the anaerobic metabolism of aromatics (toluene) and alkanes, respectively and, (ii) of genes coding for nucleotide excision repair exonucleases indicating that DNA repair processes are also activated.

Anoxia in the snow

Science.gov (United States)

Bristow, Laura A.

2018-04-01

Substantial amounts of denitrification and other anaerobic metabolisms can occur in anoxic microenvironments within marine snow particles, according to model simulations. This microbial activity may have a global impact on nitrogen cycling.

Necromass as a source of energy to microorganisms in marine sediments.

Science.gov (United States)

Bradley, J.; Amend, J.; LaRowe, D.

2017-12-01

Marine sediments constitute one of the largest, most energy-limited biospheres on Earth. Despite increasing exploration and interest characterizing microbial communities in marine sediments, the production and role of microbial dead-matter (necromass) has largely been overlooked. Necromass is produced on a global scale, yet its significance as a power source to heterotrophic microorganisms remains unknown. We developed a physical, bio-energetic and geochemical model to quantify the total power supply from necromass oxidation and the total power demand of living microorganisms in marine sediments. This model is first applied to sediments from the oligotrophic South Pacific Gyre (SPG), where organic carbon and biomass concentrations are extremely low, yet microorganisms persist for millions of years in some of the lowest energy states on Earth. We show that necromass does not supply sufficient power to support the total demands of the living community (maintenance demands of microorganisms in marine sediments for up to 60,000 years following burial. Our model assumes that all counted cells are viable. Yet, if only a fraction of counted cells are alive, the role of necromass as an electron donor in fueling microbial metabolisms is even greater. This new insight requires a reassessment of carbon fluxes in the deep biosphere. By extension, we also demonstrate a mechanism for microbial communities to persist by oxidizing necromass over geological timescales, and thereby endure unfavorable, low-energy settings that might be analogous to conditions on early Earth and on other planetary bodies.

Occurrence and removal of antibiotics, hormones and several other pharmaceuticals in wastewater treatment plants of the largest industrial city of Korea.

Science.gov (United States)

Behera, Shishir Kumar; Kim, Hyeong Woo; Oh, Jeong-Eun; Park, Hung-Suck

2011-09-15

Occurrence and removal efficiencies of 20 pharmaceuticals and personal care products (PPCPs) including antibiotics, hormones, and several other miscellaneous pharmaceuticals (analgesics, antiepileptics, antilipidemics, antihypertensives, antiseptics, and stimulants) were investigated in five wastewater treatment plants (WWTPs) of Ulsan, the largest industrial city of Korea. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The results showed that acetaminophen, atenolol and lincomycin were the main individual pollutants usually found in concentrations over 10 μg/L in the sewage influent. In the WWTPs, the concentrations of analgesic acetaminophen, stimulant caffeine, hormones estriol and estradiol decreased by over 99%. On the contrary, the antibiotic sulfamethazine, the antihypertensive metoprolol, and the antiepileptic carbamazepine exhibited removal efficiencies below 30%. Particularly, removal of antibiotics was observed to vary between -11.2 and 69%. In the primary treatment (physico-chemical processes), the removal of pharmaceuticals was insignificant (up to 28%) and removal of majority of the pharmaceuticals occurred during the secondary treatment (biological processes). The compounds lincomycin, carbamazepine, atenolol, metoprolol, and triclosan showed better removal in WWTPs employing modified activated sludge process with co-existence of anoxic-oxic condition. Further investigation into the design and operational aspects of the biological processes is warranted for the efficient removal of PPCPs, particularly antibiotics, to secure healthy water resource in the receiving downstream, thereby ensuring a sustainable water cycle management. Copyright © 2011. Published by Elsevier B.V.

Intracellular nitrate of marine diatoms as a driver of anaerobic nitrogen cycling in sinking aggregates

DEFF Research Database (Denmark)

Kamp, Anja; Stief, Peter; Bristow, Laura A.

2016-01-01

% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before...... store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom......-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly...

An Analysis of Current and Proposed Oversight Processes for the Acquisition of Large-Scale Services as Seen Through the Eyes of the Navy Marine Corps Intranet Program

National Research Council Canada - National Science Library

Rozier, JoCephas

2002-01-01

At approximately 56,9 billion, The Navy-Marine Corps Intranet (NMCI) was the largest service contract that DoD had ever awarded, The U'S, Navy viewed it as a typical multi-year, Performance Based Services Contract (PBSC...

Marine biology

International Nuclear Information System (INIS)

Thurman, H.V.; Webber, H.H.

1984-01-01

This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index

Phylogenetic Diversity of Archaea and Bacteria in the Anoxic Zone of a Meromictic Lake (Lake Pavin, France)▿ †

Science.gov (United States)

Lehours, Anne-Catherine; Evans, Paul; Bardot, Corinne; Joblin, Keith; Gérard, Fonty

2007-01-01

The compositions of archaeal and bacterial populations at different depths (60 m [mixolimnion-chemocline interface], 70 m [chemocline-subchemocline interface], 90 m, and 92 m [the water-sediment interface]) in the anoxic zone of the water column in Lake Pavin, a freshwater permanently stratified mountain lake in France, were determined. Phylogenetic trees were constructed from sequences to assess archaeal and bacterial diversity at the four sites. PMID:17261512

broken magnet highlights largest collider's engineering challenges

CERN Multimedia

Inman, Mason

2007-01-01

"Even at the world's soon-to-be largest particle accelerator - a device that promises to push the boundaries of physics - scientists need to be mindful of one of the most fundamental laws in the universe: Murphy's Law. (2 pages)

Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone.

Science.gov (United States)

Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

2014-01-01

Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2-1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2-1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms.

Influence of anoxic sensitizers on the radiation damage in biologically active DNA in aqueous solution

International Nuclear Information System (INIS)

Lafleur, M.V.M.; Loman, H.

1982-01-01

The competition between biologically active single-stranded phiX174 DNA and the anoxic radiosensitizers metronidazole, misonidazole, paranitroacetophenone or nifuroxime for OH radicals is studied. The results are compared with experiments in which the protection of the DNA by t-butanol is determined. Also the effects of the sensitizers on the chemical nature of the damage (immediate and potential break, immediate and potential base damage) is studied. It is found that in diluted aqueous solutions of DNA these radiosensitizers do not sensitize with respect to the biological inactivation. The only effect observed is a shift from potential to immediate breaks with misonidazole and also nifuroxime. (author)

Largest global shark biomass found in the northern Galápagos Islands of Darwin and Wolf

Directory of Open Access Journals (Sweden)

Pelayo Salinas de León

2016-05-01

Full Text Available Overfishing has dramatically depleted sharks and other large predatory fishes worldwide except for a few remote and/or well-protected areas. The islands of Darwin and Wolf in the far north of the Galapagos Marine Reserve (GMR are known for their large shark abundance, making them a global scuba diving and conservation hotspot. Here we report quantitative estimates of fish abundance at Darwin and Wolf over two consecutive years using stereo-video surveys, which reveal the largest reef fish biomass ever reported (17.5 t ${\\mathrm{ha}}^{-1}$ ha − 1 on average, consisting largely of sharks. Despite this, the abundance of reef fishes around the GMR, such as groupers, has been severely reduced because of unsustainable fishing practices. Although Darwin and Wolf are within the GMR, they were not fully protected from fishing until March 2016. Given the ecological value and the economic importance of Darwin and Wolf for the dive tourism industry, the current protection should ensure the long-term conservation of this hotspot of unique global value.

Post ischemic reperfusion and anoxic perfusion in the isolated heart: alteration in distribution of radionuclides and in protein synthesis

Energy Technology Data Exchange (ETDEWEB)

Schreiber, S S; Oratz, M; Rothschild, M A [Veterans Administration Hospital, New York (USA)

1980-12-01

Reperfusion after ischemia and perfusion with total anoxia were studied in the isolated guinea pig heart model, Deprivation of oxygen in both situations resulted in a marked shift of circulation from the left to the right ventricle, with markedly increased spaces of distribution of sup(99m)Tc radionuclides and albumin in the latter. In view of the complexities of measuring protein synthesis during ischemia, continuous anoxic perfusion was used to evaluate this parameter in anoxic induced arrest. There was a profound fall in protein synthesis associated with this arrest, accompanied by a fall in ATP, creatine phosphate, glycogen, potassium, and a rise in lactate production. The fall in protein synthesis was more marked in the left ventricle. The changes in synthesis were almost completely prevented by initiating cardiac arrest with high K/sup +/ (16 meq/l) at the same time as anoxia; energy metabolism remained near normal, and recovery of contractility was nearly complete. The studies demonstrated the differences in vascular distribution between the ventricles after ischemia or with perfusion anoxia, the possible difference in availability of substrate to the two ventricles under these conditions, as well as the difference in protein synthetic response, and further support the protective effect of potassium induced arrest on the hypoxic heart.

Anaerobic nitrification–denitrification mediated by Mn-oxides in meso-tidal sediments: Implications for N2 and N2O production..

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, S.O.; Javanaud, C.; Aigle, A.; Michotey, V.D.; Guasco, S.; Deborde, J.; Deflandre, B.; Anschutz, P.; Bonin, P.C.

. Interactions between metal oxides and species of nitrogen and iodine in bioturbated marine sediments. Geochim. Cosmochim. Acta 64, 2751–2763. Bartlett, R., Mortimer, R.J.G., Morris, K.M., 2007. The biogeochemistry of a manganese-rich Scottish sea loch...: Implications for the study of anoxic nitrification. Cont. Shelf Res. 27, 1501–1509. Bartlett, R., Mortimer, R.J.G., Morris, K.M., 2008. Anoxic nitrification: Evidence from Humber Estuary sediments (UK). Chem. Geol. 250, 29–39. Baumann, P., Baumann, L., 1981...

Microbiology of the Red Sea (and other) deep-sea anoxic brine lakes

KAUST Repository

Antunes, Andre

2011-05-30

Summary: The Red Sea harbours approximately 25 deep-sea anoxic brine pools. They constitute extremely unique and complex habitats with the conjugation of several extreme physicochemical parameters rendering them some of the most inhospitable environments on Earth. After 50 years of research mostly driven by chemists, geophysicists and geologists, the microbiology of the brines has been receiving increased interest in the last decade. Recent molecular and cultivation-based studies have provided us with a first glimpse on the enormous biodiversity of the local microbial communities, the identification of several new taxonomic groups, and the isolation of novel extremophiles that thrive in these environments. This review presents a general overview of these unusual biotopes and compares them with other similar environments in the Mediterranean Sea and the Gulf of Mexico, with a focus on their microbial ecology. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Sensory description of marine oils through development of a sensory wheel and vocabulary.

Science.gov (United States)

Larssen, W E; Monteleone, E; Hersleth, M

2018-04-01

The Omega-3 industry lacks a defined methodology and a vocabulary for evaluating the sensory quality of marine oils. This study was conducted to identify the sensory descriptors of marine oils and organize them in a sensory wheel for use as a tool in quality assessment. Samples of marine oils were collected from six of the largest producers of omega-3 products in Norway. The oils were selected to cover as much variation in sensory characteristics as possible, i.e. oils with different fatty acid content originating from different species. Oils were evaluated by six industry expert panels and one trained sensory panel to build up a vocabulary through a series of language sessions. A total of 184 aroma (odor by nose), flavor, taste and mouthfeel descriptors were generated. A sensory wheel based on 60 selected descriptors grouped together in 21 defined categories was created to form a graphical presentation of the sensory vocabulary. A selection of the oil samples was also evaluated by a trained sensory panel using descriptive analysis. Chemical analysis showed a positive correlation between primary and secondary oxidation products and sensory properties such as rancidity, chemical flavor and process flavor and a negative correlation between primary oxidation products and acidic. This research is a first step towards the broader objective of standardizing the sensory terminology related to marine oils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of experimental studies on technetium transfers to sediments and benthic marine species, and comparison with in situ data

Energy Technology Data Exchange (ETDEWEB)

Aprosi, G [Electricite de France, 78 - Chatou; Masson, M [Commisariat a l' Energie Atomique, Institut de Protection et de Surete Nucleaire, 50 - Cherbourg (France)

1984-01-01

To obtain basic information for the evaluation of the radiological impact of technetium (Tc) on the marine environment, investigations are performed by different laboratories. Technetium is not a natural element and the main source of production is the nuclear fuel cycle. Under anoxic conditions, in presence of reducing sediments, the distribution coefficients are very high (Ksub(D)=10/sup 3/). Concentration factors from water to species are mostly very low (FC 1 to 10); however, concentration factors up to 1000 have been observed for a few species such as macrophytic brown algae, worms and lobster. Biochemical analysis shows that Tc is bound with protein. The transfer factors between sediment and species are very low (FT<0,5). The biological half-life (Tb) was determined in some marine organisms which had accumulated the radionuclide from water-contamined food or from sediments. The loss is biphasic in storage organs (liver and kidney); uptake in the edible parts is low. Among the parameters studied (light for algae, physico-chemical form of Tc, salinity and temperature) only light and the physico-chemical forms have an effect on the accumulation of technetium. Analyses of /sup 99/Tc concentrations in species collected near the La Hague and Windscale (Sellafield) reprocessing plants confirm the experimental studies. Since sea water is likely to be an oxidant environment, technetium appears as a conservative element.

Events Calendar: Smithsonian Marine Ecosystems Exhibit: Smithsonian Marine

Science.gov (United States)

current Smithsonian research on the plants and animals of the Indian River Lagoon and marine environments Station (SMS) at Fort Pierce Smithsonian Marine Station at Fort Pierce Website Search Box History Modeling Ecosystems Virtual Tour Facebook Instagram Twitter SMS Home › Smithsonian Marine

Relative Abundance and Diversity of Bacterial Methanotrophs at the Oxic?Anoxic Interface of the Congo Deep-Sea Fan

OpenAIRE

Bessette, Sandrine; Moalic, Yann; Gautey, S?bastien; Lesongeur, Fran?oise; Godfroy, Anne; Toffin, Laurent

2017-01-01

Sitting at ∼5,000 m water depth on the Congo-Angola margin and ∼760 km offshore of the West African coast, the recent lobe complex of the Congo deep-sea fan receives large amounts of fluvial sediments (3–5% organic carbon). This organic-rich sedimentation area harbors habitats with chemosynthetic communities similar to those of cold seeps. In this study, we investigated relative abundance, diversity and distribution of aerobic methane-oxidizing bacteria (MOB) communities at the oxic–anoxic in...

Marine genomics

DEFF Research Database (Denmark)

Oliveira Ribeiro, Ângela Maria; Foote, Andrew David; Kupczok, Anne

2017-01-01

Marine ecosystems occupy 71% of the surface of our planet, yet we know little about their diversity. Although the inventory of species is continually increasing, as registered by the Census of Marine Life program, only about 10% of the estimated two million marine species are known. This lag......-throughput sequencing approaches have been helping to improve our knowledge of marine biodiversity, from the rich microbial biota that forms the base of the tree of life to a wealth of plant and animal species. In this review, we present an overview of the applications of genomics to the study of marine life, from...

Occurrence of Priming in the Degradation of Lignocellulose in Marine Sediments.

Directory of Open Access Journals (Sweden)

Evangelia Gontikaki

Full Text Available More than 50% of terrestrially-derived organic carbon (terrOC flux from the continents to the ocean is remineralised in the coastal zone despite its perceived high refractivity. The efficient degradation of terrOC in the marine environment could be fuelled by labile marine-derived material, a phenomenon known as "priming effect", but experimental data to confirm this mechanism are lacking. We tested this hypothesis by treating coastal sediments with 13C-lignocellulose, as a proxy for terrOC, with and without addition of unlabelled diatom detritus that served as the priming inducer. The occurrence of priming was assessed by the difference in lignocellulose mineralisation between diatom-amended treatments and controls in aerobic sediment slurries. Priming of lignocellulose degradation was observed only at the initial stages of the experiment (day 7 and coincided with overall high microbial activity as exemplified by total CO2 production. Lignocellulose mineralisation did not differ consistently between diatom treatments and control for the remaining experimental time (days 14-28. Based on this pattern, we hypothesize that the faster initiation of lignocellulose mineralisation in diatom-amended treatments is attributed to the decomposition of accessible polysaccharide components within the lignocellulose complex by activated diatom degraders. The fact that diatom-degraders contributed to lignocellulose degradation was also supported by the different patterns in 13C-enrichment of phospholipid fatty acids between treatments. Although we did not observe differences between treatments in the total quantity of respired lignocellulose at the end of the experiment, differences in timing could be important in natural ecosystems where the amount of time that a certain compound is subject to aerobic degradation before burial to deeper anoxic sediments may be limited.

Effects of specific inhibitors on anammox and denitrification in marine sediments.

Science.gov (United States)

Jensen, Marlene Mark; Thamdrup, Bo; Dalsgaard, Tage

2007-05-01

The effects of three metabolic inhibitors (acetylene, methanol, and allylthiourea [ATU]) on the pathways of N2 production were investigated by using short anoxic incubations of marine sediment with a 15N isotope technique. Acetylene inhibited ammonium oxidation through the anammox pathway as the oxidation rate decreased exponentially with increasing acetylene concentration; the rate decay constant was 0.10+/-0.02 microM-1, and there was 95% inhibition at approximately 30 microM. Nitrous oxide reduction, the final step of denitrification, was not sensitive to acetylene concentrations below 10 microM. However, nitrous oxide reduction was inhibited by higher concentrations, and the sensitivity was approximately one-half the sensitivity of anammox (decay constant, 0.049+/-0.004 microM-1; 95% inhibition at approximately 70 microM). Methanol specifically inhibited anammox with a decay constant of 0.79+/-0.12 mM-1, and thus 3 to 4 mM methanol was required for nearly complete inhibition. This level of methanol stimulated denitrification by approximately 50%. ATU did not have marked effects on the rates of anammox and denitrification. The profile of inhibitor effects on anammox agreed with the results of studies of the process in wastewater bioreactors, which confirmed the similarity between the anammox bacteria in bioreactors and natural environments. Acetylene and methanol can be used to separate anammox and denitrification, but the effects of these compounds on nitrification limits their use in studies of these processes in systems where nitrification is an important source of nitrate. The observed differential effects of acetylene and methanol on anammox and denitrification support our current understanding of the two main pathways of N2 production in marine sediments and the use of 15N isotope methods for their quantification.

Joint Asymptotic Distributions of Smallest and Largest Insurance Claims

Directory of Open Access Journals (Sweden)

Hansjörg Albrecher

2014-07-01

Full Text Available Assume that claims in a portfolio of insurance contracts are described by independent and identically distributed random variables with regularly varying tails and occur according to a near mixed Poisson process. We provide a collection of results pertaining to the joint asymptotic Laplace transforms of the normalised sums of the smallest and largest claims, when the length of the considered time interval tends to infinity. The results crucially depend on the value of the tail index of the claim distribution, as well as on the number of largest claims under consideration.

The Effects of work-related perceptions on retention of Hispanics in the U.S. Marine Corps

OpenAIRE

Azenon, Enrique A.

2006-01-01

This thesis investigates whether perceptions of the working environment are related to a Marine Corps member's intentions to remain on active duty. The study further examines whether perceptions about intra-organizational mobility, inequity in the workplace, and organizational support vary by racial/ethnic group. The analysis focuses on Hispanics, the largest growing ethnic minority in the United States and draws upon data from the 2002 Status of the Armed Forces: Gender and Working Relations...

The Early Toarcian oceanic anoxic event: Paleoenvironmental and paleoclimatic change across the Alpine Tethys (Switzerland)

Science.gov (United States)

Fantasia, Alicia; Föllmi, Karl B.; Adatte, Thierry; Spangenberg, Jorge E.; Montero-Serrano, Jean-Carlos

2018-03-01

Paleoenvironmental and paleoclimatic change associated with the Toarcian oceanic anoxic event (T-OAE) was evaluated in five successions located in Switzerland. They represent different paleogeographic settings across the Alpine Tethys: the northern shelf (Gipf, Riniken and Rietheim), the Sub-Briançonnais basin (Creux de l'Ours), and the Lombardian basin (Breggia). The multi-proxy approach chosen (whole-rock and clay mineralogy, phosphorus, major and trace elements) shows that local environmental conditions modulated the response to the T-OAE across the Alpine Tethys. On the northern shelf and in the Sub-Briançonnais basin, high kaolinite contents and detrital proxies (detrital index, Ti, Zr, Si) in the T-OAE interval suggest a change towards a warmer and more humid climate coupled with an increase in the chemical weathering rates. In contrast, low kaolinite content in the Lombardian basin is likely related to a more arid climate along the southern Tethys margin and/or to a deeper and more distal setting. Redox-sensitive trace-element (V, Mo, Cu, Ni) enrichments in the T-OAE intervals reveal that dysoxic to anoxic conditions developed on the northern shelf, whereas reducing conditions were less severe in the Sub-Briançonnais basin. In the Lombardian basin well-oxygenated bottom water conditions prevailed. Phosphorus (P) speciation analysis was performed at Riniken and Creux de l'Ours. This is the first report of P speciation data for T-OAE sections, clearly suggesting that high P contents during this time interval are mainly linked to the presence of an authigenic phases and fish remains. The development of oxygen-depleted conditions during the T-OAE seems to have promoted the release of the organic-bound P back into the water column, thereby further sustaining primary productivity in a positive feedback loop.

Global patterns of extinction risk in marine and non-marine systems.

Science.gov (United States)

Webb, Thomas J; Mindel, Beth L

2015-02-16

Despite increasing concern over the effects of human activities on marine ecosystems, extinction in the sea remains scarce: 19-24 out of a total of >850 recorded extinctions implies a 9-fold lower marine extinction rate compared to non-marine systems. The extent of threats faced by marine systems, and their resilience to them, receive considerable attention, but the detectability of marine extinctions is less well understood. Before its extinction or threat status is recorded, a species must be both taxonomically described and then formally assessed; lower rates of either process for marine species could thus impact patterns of extinction risk, especially as species missing from taxonomic inventories may often be more vulnerable than described species. We combine data on taxonomic description with conservation assessments from the International Union for Conservation of Nature (IUCN) to test these possibilities across almost all marine and non-marine eukaryotes. We find that the 9-fold lower rate of recorded extinctions and 4-fold lower rate of ongoing extinction risk across marine species can be explained in part by differences in the proportion of species assessed by the IUCN (3% cf. 4% of non-marine species). Furthermore, once taxonomic knowledge and conservation assessments pass a threshold level, differences in extinction risk between marine and non-marine groups largely disappear. Indeed, across the best-studied taxonomic groups, there is no difference between marine and non-marine systems, with on average between 20% and 25% of species being threatened with extinction, regardless of realm. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of Biodiesel Blend on Marine Fuel Characteristics for Marine Vessels

Directory of Open Access Journals (Sweden)

Cherng-Yuan Lin

2013-09-01

Full Text Available Biodiesel produced from vegetable oils, animal fats and algae oil is a renewable, environmentally friendly and clean alternative fuel that reduces pollutants and greenhouse gas emissions in marine applications. This study investigates the influence of biodiesel blend on the characteristics of residual and distillate marine fuels. Adequate correlation equations are applied to calculate the fuel properties of the blended marine fuels with biodiesel. Residual marine fuel RMA has inferior fuel characteristics compared with distillate marine fuel DMA and biodiesel. The flash point of marine fuel RMA could be increased by 20% if blended with 20 vol% biodiesel. The sulfur content of residual marine fuel could meet the requirement of the 2008 MARPOL Annex VI Amendment by blending it with 23.0 vol% biodiesel. In addition, the kinematic viscosity of residual marine fuel could be reduced by 12.9% and the carbon residue by 23.6% if 20 vol% and 25 vol% biodiesel are used, respectively. Residual marine fuel blended with 20 vol% biodiesel decreases its lower heating value by 1.9%. Moreover, the fuel properties of residual marine fuel are found to improve more significantly with biodiesel blending than those of distillate marine fuel.

Marine ecology

International Nuclear Information System (INIS)

Anon.

1977-01-01

Studies on marine ecology included marine pollution; distribution patterns of Pu and Am in the marine waters, sediments, and organisms of Bikini Atoll and the influence of physical, chemical, and biological factors on their movements through marine biogeochemical systems; transfer and dispersion of organic pollutants from an oil refinery through coastal waters; transfer of particulate pollutants, including sediments dispersed during construction of offshore power plants; and raft culture of the mangrove oysters

Anoxic oscillating MBR for photosynthetic bacteria harvesting and high salinity wastewater treatment.

Science.gov (United States)

Qin, Lei; Liu, Qiuhua; Meng, Qin; Fan, Zheng; He, Jinzhe; Liu, Tao; Shen, Chong; Zhang, Guoliang

2017-01-01

In this study, photosynthetic bacteria (PSB) were first harvested by MBR with pendulum type oscillation (PTO) hollow fiber module in succession and on a large scale. Based on unique properties of PSB, PSB/MBR was successfully applied for high-salinity wastewater treatment. Compared with control PSB-MBR (CMBR), PSB/PTO-MBR exhibited more excellent organics removal, which was mainly attributed to much higher biomass production for utilization. Meanwhile, the influence of light irradiation and aeration on activity of PSB was investigated in detail. Results showed that PTO-MBR with 12h light irradiation proved to be a promising and economical alternative. The cycle of dark/light and anoxic had a positive effect on PSB cultivating. Moreover, PTO-MBR exhibited much higher flux than CMBR even if large amounts of biomass existed, which demonstrated that the strong shear stress on interface of liquid-membrane played important roles on membrane fouling reduction. Copyright © 2016 Elsevier Ltd. All rights reserved.

The anaerobic and anoxic treatment of wastewater in a rotating disc reactor

International Nuclear Information System (INIS)

Breithaupt, T.; Thelitz, A.; Zhang Yicheng; Wiesmann, U.

1994-01-01

A new rotation disc reactor for anaerobic and anoxic treatment of wastewater is presented. The discs are covered with a structured textile material for immobilization of bacteria. In contrast to the wellknown rotating disc contactor the discs are completely flooded. A slow rotation causes a flow into the gaps which are formed by the parallel discs and increases the mass transfer rate. For a mean residence time of 45 min and a revolution of 38 min -1 the distribution of residence times corresponds with that of a cascade with four or five steps. This has a favourable effect on mean reaction rate if the reaction is limitted by substrate concentration. For the anaerobic treatment of a wastewater produced by the dewatering of sewage sludge (10 000 mg/l COD) and for the denitrification of a synthetic wastewater (1000 mg/l NO 3 -N) high removal rates could be obtained resulting from a high concentration of immobilized bacteria. (orig.) [de

Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

Science.gov (United States)

Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

2012-11-01

Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments.

[Analysis of carbon balance and study on mechanism in anoxic-oxic-settling-anaerobic sludge reduction process].

Science.gov (United States)

Zhai, Xiao-Min; Gao, Xu; Zhang, Man-Man; Jia, Li; Guo, Jin-Song

2012-07-01

In order to deeply explore the mechanism of sludge reduction in OSA system, carbon balance was performed in an anoxic-oxic-settling-anaerobic (A + OSA) system and a reference AO system to investigate effects of inserting a sludge holding tank in sludge cycle line on the sludge reduction process. Meanwhile, carbon mass change in each reaction unit was identified in terms of solid, liquid and gas phases. The causes of excess sludge reduction in A + OSA system were deduced. The carbon balance results show that when the hydraulic retention time in the sludge holding tank is 7.14 h, carbon percent in solid phase of the sludge reduction system is nearly 50% higher than that of the reference system, supporting the consequence that sludge reduction rate of 49.98% had been achieved. The insertion of a sludge holding tank in the sludge return circuit can be effective in sludge reduction. Carbon changes in each unit reveal that the amount of carbon consumed for biosynthesis in the anoxic and oxic tanks (main reaction zone) of the sludge reduction system is higher than in that of the reference system. Sludge decay is observed in the sludge holding tank. Furthermore, CH4 released from the sludge holding tank is significantly higher than that from the main reaction zone. The DGGE profiles show that there are hydrolytic-fermentative bacteria in the sludge holding tank related to sludge decay. The excess sludge reduction in the A + OSA system could be a result of the combination of sludge decay in the sludge holding tank and sludge compensatory growth in the main reaction cell.

Guaranteeing uptime at worl's largest particle physics lab

CERN Multimedia

Brodkin, Jon

2007-01-01

"As the European agency CERN was gearing up to build the world's largest particle accelerator, officials there knew they could not afford to have problems in their technical infrastructure cause any downtime." (1 page)

Sedimentary cobalt concentrations track marine redox evolution

Science.gov (United States)

Swanner, Elizabeth; Planavsky, Noah; Lalonde, Stefan; Robbins, Jamie; Bekker, Andrey; Rouxel, Olivier; Konhauser, Kurt O.; Mojzsis, Stephen J.

2013-04-01

Oxygen production by photosynthesis drove the redox evolution of the atmosphere and ocean. Primary productivity by oxygenic photosynthesizers in the modern surface ocean is limited by trace nutrients such as iron, but previous studies have also observed high Co uptake associated with natural cyanobacterial populations. Constraining the size and variation of the oceanic reservoir of Co through time will help to understand the regulation of primary productivity and hence oxygenation through time. In this study, Co concentrations from iron formations (IF), shales and marine pyrites deposited over nearly 4 billion years of Earth's history are utilized to reconstruct secular changes in the mechanisms of Co removal from the oceanic reservoir. The Co reservoir prior to ~2 Ga was dominated by hydrothermal inputs and Fe(III)oxyhydroxides were likely involved in the removal of Co from the water column. Fe(II) oxidation in the water column resulted in the deposition of IF in the Archean and Paleoproterozoic, and the Co inventory of IF records a large oceanic reservoir of Co during this time. Lower Co concentrations in sediments during the Middle Proterozoic signify a decrease in the oceanic reservoir due to the expansion euxinic environments, corresponding to the results of previous studies. A transition to an oxidized deep ocean in the Phanerozoic is evidenced by correlation between Co and manganese (Mn) concentrations in hydrothermal and exhalative deposits, and in marine pyrites. This relationship between Co and Mn, signifying deposition of Co in association with Mn(IV)oxides, does not occur in the Precambrian. Mn(II) oxidation occurs at higher redox potentials than that required for Fe(II) oxidation, and the extent of Mn redox cycling prior to full ventilation of the oceans at the end of the Neoproterozoic was likely limited to spatially restricted oxic surface waters. In this regard, Co is another valuable redox proxy for tracking the growth and decline in oxygenated

Production of class a biosolids with anoxic low dose alkaline treatment and odor management

Energy Technology Data Exchange (ETDEWEB)

Abu-Orf, M.M.; Brewster, J.; Oleszkiewicz, J.; Reimers, R.S.; Lagasse, P.; Amy, B.; Glindemann, D.

2003-07-01

The feasibility of full-scale anoxic disinfection of dewatered and digested sludge from Winnipeg, Manitoba with low lime doses and lagoon fly ash was investigated to determine if a class A product could be produced. Lime doses of 50g, 100g, and 200g per kg of biosolids (dry) were used along with fly ash doses of 500g. 1000g. and 1500g per kg of biosolids (dry). The mixed product was buried in eight-10 cubic meter trenches at the West End Water Pollution Control Center In Winnipeg. The trenches were backfilled with dirt and trapped to simulate anoxic conditions. Sampling cages were packed with the mixed product and pathogens non-indigenous to Winnipeg's biosolids. The cages were buried amongst the mixed biosolids in the trench. The non-indigenous pathogens spiked in the laboratory were the helminth Ascaris suum and the enteric virus reovirus. Samples were removed at days 12, 40, 69, 291, and 356 and were tested for the presence of fecal Coliform, Clostridium perfringens spores, Ascaris suum eggs, and reovirus. The pH, total solids, and free ammonia content of the mixed product were also determined for each sample. Odor was quantified for samples at both 291 and 356 days. Fecal Coliform bacteria and reovirus were completely inactivated for doses as low as 100g lime per kg biosolids (dry) and 50g lime + 500g fly ash per kg biosolids (dry). Spores of the bacteria C. perfringens experienced a 4-log reduction when treated with 100g lime per kg biosolids and a 5-log reduction when treated with doses as low as 50g lime + 500g fly ash per kg biosolids (dry) after 69 days. Ascaris eggs were completely inactivated in 5 gram packets for all treatments involving 100g lime per kg biosolids (dry) after 69 days. Class A pathogen requirements were met for all treatments involving a lime dose of at least 100g per kg biosolids. The odor potential from the produced biosolids is also assessed. (author)

Marine pollution

International Nuclear Information System (INIS)

Albaiges, J.

1989-01-01

This book covers the following topics: Transport of marine pollutants; Transformation of pollutants in the marine environment; Biological effects of marine pollutants; Sources and transport of oil pollutants in the Persian Gulf; Trace metals and hydrocarbons in Syrian coastal waters; and Techniques for analysis of trace pollutants

A terrestrial Eocene stack: tying terrestrial lake ecology to marine carbon cycling through the Early Eocene Climatic Optimum

Science.gov (United States)

Grogan, D. S.; Whiteside, J. H.; Musher, D.; Rosengard, S. Z.; Vankeuren, M. A.; Pancost, R. D.

2010-12-01

The lacustrine Green River Formation is known to span ≥15 million years through the early-middle Eocene, and recent work on radioisotopic dating has provided a framework on which to build ties to the orbitally-tuned marine Eocene record. Here we present a spliced stack of Fischer assay data from drilled cores of the Green River Formation that span both an East-West and a North-South transect of the Uinta Basin of Utah. Detailed work on two cores demonstrate that Fischer assay measurements covary with total organic carbon and bulk carbon isotopes, allowing us to use Fisher assay results as a representative carbon cycling proxy throughout the stack. We provide an age model for this core record by combining radioisotopic dates of tuff layers with frequency analysis of Fischer assay measurements. Identification of orbital frequencies tied directly to magnetochrons through radioisotopic dates allows for a direct comparison of the terrestrial to the marine Eocene record. Our analysis indicates that the marker beds used to correlate the stack cores represent periods of enhanced lake productivity and extreme carbon burial; however, unlike the hyperthermal events that are clearly marked in the marine Eocene record, the hydrocarbon-rich "Mahogany Bed" period of burial does not correspond to a clear carbon isotope excursion. This suggests that the terrestrial realm may have experienced extreme ecological responses to relatively small perturbations in the carbon cycle during the Early Eocene Climatic Optimum. To investigate the ecological responses to carbon cycle perturbations through the hydrocarbon rich beds, we analyzed a suite of microbial biomarkers, finding evidence for cyanobacteria, dinoflagellates, and potentially green sulfur bacteria. These taxa indicate fluctuating oxic/anoxic conditions in the lake during abrupt intervals of carbon burial, suggesting a lake biogeochemical regime with no modern analogues.

Reconstructed Marine Fisheries Catches at a Remote Island Group: Pitcairn Islands (1950–2014

Directory of Open Access Journals (Sweden)

Amy R. Coghlan

2017-09-01

Full Text Available The remote Pitcairn Island Group in the South Pacific was designated one of the world's largest marine reserves in 2016, encompassing some of the few remaining near-pristine areas within EEZ boundaries. Pitcairn's domestic fisheries are small-scale, and consist mainly of subsistence (non-commercial and limited artisanal (commercial catches. There is no locally-based industrial (large-scale commercial fishery and the level of foreign industrial activity in recent times has been minimal, due in part to the low biomass of commercially valuable species, along with economic constraints of the EEZ's geographic isolation. Using a catch reconstruction method we estimated the total domestic marine catches for the Pitcairn Islands from 1950 to 2014. We show that overall the Pitcairn Islands' small-scale fisheries catches were almost 2.5 times higher than the data reported by the Food and Agriculture Organization (FAO of the United Nations on behalf of the Pitcairn Islands, however, this primarily reflects discrepancies prior to the 1980s. Overall, catches for the subsistence and artisanal sectors started with around 12 t·year−1 in 1950, but declined to 4 t·year−1 by 2014. Domestic reconstructed subsistence catch levels were entirely driven by changes in the human population on the island, with reconstructed artisanal catches only occurring in recent years (2000 onwards. Industrial fishing is entirely executed by foreign vessels, this catch is considerably variable throughout the years and ceases entirely in 2006. The implementation of one of the world's largest marine reserves surrounding the offshore waters of Pitcairn Island has been specifically designed not to affect the rates of subsistence and artisanal fishing conducted by the resident population. Although there is no industrial fishing in the Pitcairn EEZ at present, climate change is predicted to influence the routes of migrating commercially-targeted species, potentially altering fishing

Genome of Phaeocystis globosa virus PgV-16T highlights the common ancestry of the largest known DNA viruses infecting eukaryotes

Science.gov (United States)

Santini, Sebastien; Jeudy, Sandra; Bartoli, Julia; Poirot, Olivier; Lescot, Magali; Abergel, Chantal; Barbe, Valérie; Wommack, K. Eric; Noordeloos, Anna A. M.; Brussaard, Corina P. D.; Claverie, Jean-Michel

2013-01-01

Large dsDNA viruses are involved in the population control of many globally distributed species of eukaryotic phytoplankton and have a prominent role in bloom termination. The genus Phaeocystis (Haptophyta, Prymnesiophyceae) includes several high-biomass-forming phytoplankton species, such as Phaeocystis globosa, the blooms of which occur mostly in the coastal zone of the North Atlantic and the North Sea. Here, we report the 459,984-bp-long genome sequence of P. globosa virus strain PgV-16T, encoding 434 proteins and eight tRNAs and, thus, the largest fully sequenced genome to date among viruses infecting algae. Surprisingly, PgV-16T exhibits no phylogenetic affinity with other viruses infecting microalgae (e.g., phycodnaviruses), including those infecting Emiliania huxleyi, another ubiquitous bloom-forming haptophyte. Rather, PgV-16T belongs to an emerging clade (the Megaviridae) clustering the viruses endowed with the largest known genomes, including Megavirus, Mimivirus (both infecting acanthamoeba), and a virus infecting the marine microflagellate grazer Cafeteria roenbergensis. Seventy-five percent of the best matches of PgV-16T–predicted proteins correspond to two viruses [Organic Lake phycodnavirus (OLPV)1 and OLPV2] from a hypersaline lake in Antarctica (Organic Lake), the hosts of which are unknown. As for OLPVs and other Megaviridae, the PgV-16T sequence data revealed the presence of a virophage-like genome. However, no virophage particle was detected in infected P. globosa cultures. The presence of many genes found only in Megaviridae in its genome and the presence of an associated virophage strongly suggest that PgV-16T shares a common ancestry with the largest known dsDNA viruses, the host range of which already encompasses the earliest diverging branches of domain Eukarya. PMID:23754393

Deep coastal marine taphonomy: investigation into carcass decomposition in the Saanich Inlet, British Columbia using a baited camera.

Directory of Open Access Journals (Sweden)

Gail S Anderson

Full Text Available Decomposition and faunal colonization of a carcass in the terrestrial environment has been well studied, but knowledge of decomposition in the marine environment is based almost entirely on anecdotal reports. Three pig carcasses were deployed in Saanich Inlet, BC, over 3 years utilizing Ocean Network Canada's VENUS observatory. Each carcass was deployed in late summer/early fall at 99 m under a remotely controlled camera and observed several times a day. Dissolved oxygen, temperature, salinity, density and pressure were continuously measured. Carcass 1 was immediately colonized by Munida quadrispina, Pandalus platyceros and Metacarcinus magister, rapidly scavenged then dragged from view by Day 22. Artifacts specific to each of the crustaceans' feeding patterns were observed. Carcass 2 was scavenged in a similar fashion. Exposed tissue became covered by Orchomenella obtusa (Family Lysianassidae which removed all the internal tissues rapidly. Carcass 3 attracted only a few M. quadrispina, remaining intact, developing a thick filamentous sulphur bacterial mat, until Day 92, when it was skeletonized by crustacea. The major difference between the deployments was dissolved oxygen levels. The first two carcasses were placed when oxygen levels were tolerable, becoming more anoxic. This allowed larger crustacea to feed. However, Carcass 3 was deployed when the water was already extremely anoxic, which prevented larger crustacea from accessing the carcass. The smaller M. quadrispina were unable to break the skin alone. The larger crustacea returned when the Inlet was re-oxygenated in spring. Oxygen levels, therefore, drive the biota in this area, although most crustacea endured stressful levels of oxygen to access the carcasses for much of the time. These data will be valuable in forensic investigations involving submerged bodies, indicating types of water conditions to which the body has been exposed, identifying post-mortem artifacts and providing

Differential modification of oxic and anoxic components of radiation damage by t-butanol, an. OH radical scavenger

Energy Technology Data Exchange (ETDEWEB)

Afzal, S M.J.; Kesavan, P C [Jawaharlal Nehru Univ., New Delhi (India). School of Life Sciences

1979-03-01

Caryopses of a hull-less barley strain (IB 65) were gamma-irradiated (10 to 45 krad) in oxygenated and oxygen-free water in the presence of t-butanol (5 x 10/sup -3/ to 10/sup -1/M), and eight-day seedling growth was then measured. The results showed that t-butanol afforded partial radio-protection against oxic damage and potentiated the anoxic damage in both dry and metabolizing barley seeds. Attention is given to the possible basic differences in the oxygen effect(s) in prokaryotes and eukaryotes, and to the involvement of .OH radicals under these conditions.

Delusional jealousy and person directed hostility: 5-year follow-up of a patient after anoxic brain injury.

Science.gov (United States)

Shah, Rajendra; Faruqui, Rafey A

2013-01-01

This study presents a case report on the emergence of delusional jealousy and person-directed hostility in a patient following anoxic brain injury. The patient did not have a pre-injury history of mental illness, nor a family history of a psychotic disorder. This patient was followed-up over a 5-year period and his history of treatment response, violence risk management and successful rehabilitation are presented. This study also highlights issues in relation to continuation of treatment with antipsychotic medication, use of compulsory admission under the Mental Health Act and principles of risk assessment and risk management.

The world's largest LNG producer's next market

International Nuclear Information System (INIS)

Fuller, R.; Isworo Suharno; Simandjuntak, W.M.P.

1996-01-01

The development of the domestic gas market in Indonesia, the world's largest liquefied natural gas producing country, is described as part of the overall impact of the country's oil and gas production. The first large scale use of natural gas in Indonesia was established in 1968 when a fertiliser plant using gas as the feedstock was built. Ultimately, through increased yields, this has enabled Indonesia to be self-sufficient in rice and an exporter of fertiliser. Problems which stand in the way of further developments include: capital, though Pertamina and PGN are perceived as attractive for foreign investment; the lack of a regulatory framework for gas; geographical constraints, among them the fact that the gas deposits are remote from the largest population concentrations; lack of infrastructure. There are nevertheless plans for expansion and the provision of an integrated gas pipeline system. Pertamina, which has responsibility for all oil and gas developments, and PGN, whose primary role has been as a manufacturer and distributor of gas, are now working together in the coordination of all gas activities. (10 figures). (UK)

Scenarios for potential radionuclide release from marine reactors dumped in the Kara Sea

International Nuclear Information System (INIS)

Lynn, N.; Mount, M.; Gussgard, K.

1995-01-01

The largest inventory of radioactive materials dumped in the Kara Sea by the former Soviet Union comes from the spent nuclear fuel (SNF) of seven marine reactors, the current (1994) inventory of which makes a total of approximately 4.7x10 15 Bq. In progressing its work for the International Arctic Seas Assessment Project, under the auspices of the International Atomic Energy Agency, the Source Term Working Group has analysed the Source Term and subsequently developed a number of model scenarios for the potential release patterns of radionuclides into the Kara Sea from the SNF and activated components dumped within the marine reactors.These models are based on the present and future conditions of the barrier materials and their configuration within the dumped objects. They account for progressive corrosion of the outer and inner steel barriers, breakdown of the organic fillers, and degradation and leaching from the SNFs. Annual release rates are predicted to four thousand years into the future. 5 refs., 1 fig., 1 tab

New Waves in Marine Science Symposium: Marine Animal Communication.

Science.gov (United States)

Allen, Betty, Comp.

1989-01-01

Presented are the abstracts from three research projects on marine social systems which were a part of a marine science symposium. Five sets of activities on marine animal communication are included, one each for grades K-2, 3-5, 6-8 and 9-12, and informal education. (CW)

Evaluating Late Cretaceous OAEs and the influence of marine incursions on organic carbon burial in an expansive East Asian paleo-lake

Science.gov (United States)

Jones, Matthew M.; Ibarra, Daniel E.; Gao, Yuan; Sageman, Bradley B.; Selby, David; Chamberlain, C. Page; Graham, Stephan A.

2018-02-01

Expansive Late Cretaceous lacustrine deposits of East Asia offer unique stratigraphic records to better understand regional responses to global climate events, such as oceanic anoxic events (OAEs), and terrestrial organic carbon burial dynamics. This study presents bulk organic carbon isotopes (δ13Corg), elemental concentrations (XRF), and initial osmium ratios (187Os/188Os, Osi) from the Turonian-Coniacian Qingshankou Formation, a ∼5 Ma lacustrine mudstone succession in the Songliao Basin of northeast China. A notable δ13Corg excursion (∼ + 2.5‰) in organic carbon-lean Qingshankou Members 2-3 correlates to OAE3 in the Western Interior Basin (WIB) of North America within temporal uncertainty of high-precision age models. Decreases in carbon isotopic fractionation (Δ13C) through OAE3 in the WIB and Songliao Basin, suggest that significantly elevated global rates of organic carbon burial drew down pCO2, likely cooling climate. Despite this, Osi chemostratigraphy demonstrates no major changes in global volcanism or weathering trends through OAE3. Identification of OAE3 in a lake system is consistent with lacustrine records of other OAEs (e.g., Toarcian OAE), and underscores that terrestrial environments were sensitive to climate perturbations associated with OAEs. Additionally, the relatively radiogenic Osi chemostratigraphy and XRF data confirm that the Qingshankou Formation was deposited in a non-marine setting. Organic carbon-rich intervals preserve no compelling Osi evidence for marine incursions, an existing hypothesis for generating Member 1's prolific petroleum source rocks. Based on our results, we present a model for water column stratification and source rock deposition independent of marine incursions, detailing dominant biogeochemical cycles and lacustrine organic carbon burial mechanisms.

Worlds Largest Wave Energy Project 2007 in Wales

DEFF Research Database (Denmark)

Christensen, Lars; Friis-Madsen, Erik; Kofoed, Jens Peter

2006-01-01

This paper introduces world largest wave energy project being developed in Wales and based on one of the leading wave energy technologies. The background for the development of wave energy, the total resource ands its distribution around the world is described. In contrast to wind energy turbines...... Dragon has to be scaled in accordance with the wave climate at the deployment site, which makes the Welch demonstrator device the worlds largest WEC so far with a total width of 300 meters. The project budget, the construction methods and the deployment site are also given....... a large number of fundamentally different technologies are utilised to harvest wave energy. The Wave Dragon belongs to the wave overtopping class of converters and the paper describes the fundamentals and the technical solutions used in this wave energy converter. An offshore floating WEC like the Wave...

Marine sulfate-reducing bacteria cause serious corrosion of iron under electroconductive biogenic mineral crust

Science.gov (United States)

Enning, Dennis; Venzlaff, Hendrik; Garrelfs, Julia; Dinh, Hang T; Meyer, Volker; Mayrhofer, Karl; Hassel, Achim W; Stratmann, Martin; Widdel, Friedrich

2012-01-01

Iron (Fe0) corrosion in anoxic environments (e.g. inside pipelines), a process entailing considerable economic costs, is largely influenced by microorganisms, in particular sulfate-reducing bacteria (SRB). The process is characterized by formation of black crusts and metal pitting. The mechanism is usually explained by the corrosiveness of formed H2S, and scavenge of ‘cathodic’ H2 from chemical reaction of Fe0 with H2O. Here we studied peculiar marine SRB that grew lithotrophically with metallic iron as the only electron donor. They degraded up to 72% of iron coupons (10 mm × 10 mm × 1 mm) within five months, which is a technologically highly relevant corrosion rate (0.7 mm Fe0 year−1), while conventional H2-scavenging control strains were not corrosive. The black, hard mineral crust (FeS, FeCO3, Mg/CaCO3) deposited on the corroding metal exhibited electrical conductivity (50 S m−1). This was sufficient to explain the corrosion rate by electron flow from the metal (4Fe0 → 4Fe2+ + 8e−) through semiconductive sulfides to the crust-colonizing cells reducing sulfate (8e− + SO42− + 9H+ → HS− + 4H2O). Hence, anaerobic microbial iron corrosion obviously bypasses H2 rather than depends on it. SRB with such corrosive potential were revealed at naturally high numbers at a coastal marine sediment site. Iron coupons buried there were corroded and covered by the characteristic mineral crust. It is speculated that anaerobic biocorrosion is due to the promiscuous use of an ecophysiologically relevant catabolic trait for uptake of external electrons from abiotic or biotic sources in sediments. PMID:22616633

Marine Robot Autonomy

CERN Document Server

2013-01-01

Autonomy for Marine Robots provides a timely and insightful overview of intelligent autonomy in marine robots. A brief history of this emerging field is provided, along with a discussion of the challenges unique to the underwater environment and their impact on the level of intelligent autonomy required.  Topics covered at length examine advanced frameworks, path-planning, fault tolerance, machine learning, and cooperation as relevant to marine robots that need intelligent autonomy.  This book also: Discusses and offers solutions for the unique challenges presented by more complex missions and the dynamic underwater environment when operating autonomous marine robots Includes case studies that demonstrate intelligent autonomy in marine robots to perform underwater simultaneous localization and mapping  Autonomy for Marine Robots is an ideal book for researchers and engineers interested in the field of marine robots.      

First Experience from the World Largest fully commercial Solar Heating Plant

DEFF Research Database (Denmark)

Heller, Alfred; Furbo, Simon

1997-01-01

The first experience from the largest solar heating plant in the world is given. The plant is situated in Marstal and is has a total area of 8000 square m.......The first experience from the largest solar heating plant in the world is given. The plant is situated in Marstal and is has a total area of 8000 square m....

Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation

Directory of Open Access Journals (Sweden)

N. Meskhidze

2011-11-01

Full Text Available Marine organic aerosol emissions have been implemented and evaluated within the National Center of Atmospheric Research (NCAR's Community Atmosphere Model (CAM5 with the Pacific Northwest National Laboratory's 7-mode Modal Aerosol Module (MAM-7. Emissions of marine primary organic aerosols (POA, phytoplankton-produced isoprene- and monoterpenes-derived secondary organic aerosols (SOA and methane sulfonate (MS⁻ are shown to affect surface concentrations of organic aerosols in remote marine regions. Global emissions of submicron marine POA is estimated to be 7.9 and 9.4 Tg yr⁻¹, for the Gantt et al. (2011 and Vignati et al. (2010 emission parameterizations, respectively. Marine sources of SOA and particulate MS⁻ (containing both sulfur and carbon atoms contribute an additional 0.2 and 5.1 Tg yr⁻¹, respectively. Widespread areas over productive waters of the Northern Atlantic, Northern Pacific, and the Southern Ocean show marine-source submicron organic aerosol surface concentrations of 100 ng m⁻³, with values up to 400 ng m⁻³ over biologically productive areas. Comparison of long-term surface observations of water insoluble organic matter (WIOM with POA concentrations from the two emission parameterizations shows that despite revealed discrepancies (often more than a factor of 2, both Gantt et al. (2011 and Vignati et al. (2010 formulations are able to capture the magnitude of marine organic aerosol concentrations, with the Gantt et al. (2011 parameterization attaining better seasonality. Model simulations show that the mixing state of the marine POA can impact the surface number concentration of cloud condensation nuclei (CCN. The largest increases (up to 20% in CCN (at a supersaturation (S of 0.2% number concentration are obtained over biologically productive ocean waters when marine organic aerosol is assumed to be externally mixed with sea-salt. Assuming

Marine habitat mapping at Labuan Marine Park, Federal Territory of Labuan, Malaysia

Science.gov (United States)

Mustajap, Fazliana; Saleh, Ejria; Madin, John; Hamid, Shahimah Abdul

2015-06-01

Marine habitat mapping has recently become essential in coastal marine science research. It is one of the efforts to understand marine ecosystems, and thus to protect them. Habitat mapping is integral to marine-related industries such as fisheries, aquaculture, forestry and tourism. An assessment of marine habitat mapping was conducted at Labuan Marine Park (LMP), a marine protected area in the Federal Territory of Labuan. It is surrounded by shallow water within its islands (Kuraman, Rusukan Kecil and Rusukan Besar) with an area of 39.7 km2. The objectives of the study are to identify the substrate and types of marine habitat present within the park. Side scan sonar (SSS) (Aquascan TM) was used to determine the substrates and habitat while ground truthings were done through field observation and SCUBA diving survey. Seabed classification and marine habitat was based on NOAA's biogeography program. Three substrate types (sand, rock, silt) were identified in this area. The major marine habitats identified are corals, macro algae and small patches of sea grass. The study area is an important refuge for spawning and juvenile fish and supports the livelihood of the coastal communities on Labuan Island. Therefore, proper management is crucial in order to better maintain the marine protected area. The findings are significant and provide detailed baseline information on marine habitat for conservation, protection and future management in LMP.

Challenges with the largest commercial hydrogen station in the world

Energy Technology Data Exchange (ETDEWEB)

Charbonneau, Thomas; Gauthier, Pierre [Air Liquide Canada (Canada)

2010-07-01

This abstract's objective is to share with the participants the story of the largest hydrogen fueling station made to this date and to kick-start the story, we will cover the challenges; first the technical ones; the operational ones; the distribution ones and; the financial ones. We will then move on to review the logistic (geographic) issues raised by the project and conclude our presentation by sharing the output values of the largest fueling station built so far in the world. (orig.)

A greigite-based magnetostratigraphic time frame for the Late Miocene to recent DSDP Leg 42B Cores from the Black Sea

NARCIS (Netherlands)

Van Baak, Christiaan G. C.; Vasiliev, Iuliana; Palcu, Dan V.; Dekkers, Mark J.; Krijgsman, Wout

2016-01-01

Throughout the Late Neogene, the Black Sea experienced large paleoenvironmental changes, switching between (anoxic) marine conditions when connected to the Mediterranean Sea and (oxic) freshwater conditions at times of isolation. We create a magnetostratigraphic time frame for three sites drilled

Phylogenomics of Rhodobacteraceae reveals evolutionary adaptation to marine and non-marine habitats.

Science.gov (United States)

Simon, Meinhard; Scheuner, Carmen; Meier-Kolthoff, Jan P; Brinkhoff, Thorsten; Wagner-Döbler, Irene; Ulbrich, Marcus; Klenk, Hans-Peter; Schomburg, Dietmar; Petersen, Jörn; Göker, Markus

2017-06-01

Marine Rhodobacteraceae (Alphaproteobacteria) are key players of biogeochemical cycling, comprise up to 30% of bacterial communities in pelagic environments and are often mutualists of eukaryotes. As 'Roseobacter clade', these 'roseobacters' are assumed to be monophyletic, but non-marine Rhodobacteraceae have not yet been included in phylogenomic analyses. Therefore, we analysed 106 genome sequences, particularly emphasizing gene sampling and its effect on phylogenetic stability, and investigated relationships between marine versus non-marine habitat, evolutionary origin and genomic adaptations. Our analyses, providing no unequivocal evidence for the monophyly of roseobacters, indicate several shifts between marine and non-marine habitats that occurred independently and were accompanied by characteristic changes in genomic content of orthologs, enzymes and metabolic pathways. Non-marine Rhodobacteraceae gained high-affinity transporters to cope with much lower sulphate concentrations and lost genes related to the reduced sodium chloride and organohalogen concentrations in their habitats. Marine Rhodobacteraceae gained genes required for fucoidan desulphonation and synthesis of the plant hormone indole 3-acetic acid and the compatible solutes ectoin and carnitin. However, neither plasmid composition, even though typical for the family, nor the degree of oligotrophy shows a systematic difference between marine and non-marine Rhodobacteraceae. We suggest the operational term 'Roseobacter group' for the marine Rhodobacteraceae strains.

A dataset on the species composition of amphipods (Crustacea) in a Mexican marine national park: Alacranes Reef, Yucatan

OpenAIRE

Paz,Carlos; Simões,Nuno; Pech,Daniel

2018-01-01

Abstract Background Alacranes Reef was declared as a National Marine Park in 1994. Since then, many efforts have been made to inventory its biodiversity. However, groups such as amphipods have been underestimated or not considered when benthic invertebrates were inventoried. Here we present a dataset that contributes to the knowledge of benthic amphipods ( Crustacea , Peracarida ) from the inner lagoon habitats from the Alacranes Reef National Park, the largest coral reef ecosystem in the Gul...

Marine nitrogen cycle

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A.

) such as the Marine nitrogen cycle The marine nitrogen cycle. ‘X’ and ‘Y’ are intra-cellular intermediates that do not accumulate in water column. (Source: Codispoti et al., 2001) Page 1 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www... and nitrous oxide budgets: Moving targets as we enter the anthropocene?, Sci. Mar., 65, 85-105, 2001. Page 2 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www.eoearth.org/article/Marine_nitrogen_cycle square6 Gruber, N.: The dynamics...

A pore water study of plutonium in a seasonally anoxic lake

International Nuclear Information System (INIS)

Buesseler, K.O.; Benoit, G.; Sholkovitz, E.R.

1985-01-01

Data are presented on the distribution of sup(239,240)Pu in the pore waters of two cores taken from a seasonally anoxic lake. The pore water sup(239,240)Pu profile exhibits a subsurface activity maximum of 230 +- 30 μBq kg -1 in the 3-6 cm interval in June, as compared to an activity of 5 +- 3 μBq kg -1 in the overlying water. The pore water sup(239,240)Pu profile in June follows the solid phase distribution pattern of sup(239,240)Pu and also the pore water distributions of Fe and Mn. Under more reducing conditions in August, pore water sup(239,240)Pu activities drop off to undetectable levels at all depths. This rapid change in the pore water sup(239,240)Pu activity reflects the dynamic nature of Pu diagenesis in these sediments. Potential diffusional fluxes of sup(239,240)Pu into the lake's hypolimnion in June are calculated to be on the order of 2.5 μBq cm -2 y -1 . This flux would not be significant in altering the solid phase sup(239,240)Pu inventory (2.8 x 10 4 μBq cm -2 ). (author)

Growth and chemosensory behavior of sulfate-reducing bacteria in oxygen-sulfide gradients

DEFF Research Database (Denmark)

Sass, Andrea M.; Wieland, Andrea Eschemann; Kühl, Michael

2002-01-01

Growth and chemotactic behavior in oxic–anoxic gradients were studied with two freshwater and four marine strains of sulfate-reducing bacteria related to the genera Desulfovibrio, Desulfomicrobium or Desulfobulbus. Cells were grown in oxygen–sulfide counter-gradients within tubes filled with agar...... chemotactically to lactate, nitrate, sulfate and thiosulfate, and even sulfide functioned as an attractant. In oxic–anoxic gradients the bacteria moved away from high oxygen concentrations and formed bands at the outer edge of the oxic zone at low oxygen concentration (... to actively change the extension and slope of the gradients by oxygen reduction with lactate or even sulfide as electron donor. Generally, the chemotactic behavior was in agreement with a defense strategy that re-establishes anoxic conditions, thus promoting anaerobic growth and, in a natural community...

Functional Molecular Diversity of Marine Dissolved Organic Matter Is Reduced during Degradation

Directory of Open Access Journals (Sweden)

Andrea Mentges

2017-06-01

Full Text Available Dissolved organic matter (DOM is a highly diverse mixture of compounds, accounting for one of the world's largest active carbon pools. The surprising recalcitrance of some DOM compounds to bacterial degradation has recently been associated with its diversity. However, little is known about large-scale patterns of marine DOM diversity and its change through degradation, in particular considering the functional diversity of DOM. Here, we analyze the development of marine DOM diversity during degradation in two data sets comprising DOM of very different ages: a three-year mesocosm experiment and highly-resolved field samples from the Atlantic and Southern Ocean. The DOM molecular composition was determined using ultra-high resolution mass spectrometry. We quantify DOM diversity using three conceptually different diversity measures, namely richness of molecular formulas, abundance-based diversity, and functional molecular diversity. Using these measures we find stable molecular richness of DOM with age >1 year, systematic changes in the molecules' abundance distribution with degradation state, and increasing homogeneity with respect to chemical properties for more degraded DOM. Coinciding with differences in sea water density, the spatial field data separated clearly into regions of high and low diversity. The joint application of different diversity measures yields a comprehensive overview on temporal and spatial patterns of molecular diversity, valuable for general conclusions on drivers and consequences of marine DOM diversity.

Large-Scale Trade in Legally Protected Marine Mollusc Shells from Java and Bali, Indonesia.

Directory of Open Access Journals (Sweden)

Vincent Nijman

Full Text Available Tropical marine molluscs are traded globally. Larger species with slow life histories are under threat from over-exploitation. We report on the trade in protected marine mollusc shells in and from Java and Bali, Indonesia. Since 1987 twelve species of marine molluscs are protected under Indonesian law to shield them from overexploitation. Despite this protection they are traded openly in large volumes.We collected data on species composition, origins, volumes and prices at two large open markets (2013, collected data from wholesale traders (2013, and compiled seizure data by the Indonesian authorities (2008-2013. All twelve protected species were observed in trade. Smaller species were traded for 32,000 shells valued at USD500,000, chambered nautilus (Nautilus pompilius (>3,000 shells, USD60,000 and giant clams (Tridacna spp. (>2,000 shells, USD45,000 were traded in largest volumes. Two-thirds of this trade was destined for international markets, including in the USA and Asia-Pacific region.We demonstrated that the trade in protected marine mollusc shells in Indonesia is not controlled nor monitored, that it involves large volumes, and that networks of shell collectors, traders, middlemen and exporters span the globe. This impedes protection of these species on the ground and calls into question the effectiveness of protected species management in Indonesia; solutions are unlikely to be found only in Indonesia and must involve the cooperation of importing countries.

Mathematical modeling of nitrous oxide production in an anaerobic/oxic/anoxic process.

Science.gov (United States)

Ding, Xiaoqian; Zhao, Jianqiang; Hu, Bo; Chen, Ying; Ge, Guanghuan; Li, Xiaoling; Wang, Sha; Gao, Kun; Tian, Xiaolei

2016-12-01

This study incorporates three currently known nitrous oxide (N 2 O) production pathways: ammonium-oxidizing bacteria (AOB) denitrification, incomplete hydroxylamine (NH 2 OH) oxidation, and heterotrophic denitrification on intracellular polymers, into a mathematical model to describe N 2 O production in an anaerobic/oxic/anoxic (AOA) process for the first time. The developed model was calibrated and validated by four experimental cases, then evaluated by two independent anaerobic/aerobic (AO) studies from literature. The modeling results displayed good agreement with the measured data. N 2 O was primarily generated in the aerobic stage by AOB denitrification (67.84-81.64%) in the AOA system. Smaller amounts of N 2 O were produced via incomplete NH 2 OH oxidation (15.61-32.17%) and heterotrophic denitrification on intracellular polymers (0-12.47%). The high nitrite inhibition on N 2 O reductase led to the increased N 2 O accumulation in heterotrophic denitrification on intracellular polymers. The new model was capable of modeling nitrification-denitrification dynamics and heterotrophic denitrification on intracellular polymers in the AOA system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile

Science.gov (United States)

Parris, Darren J.; Ganesh, Sangita; Edgcomb, Virginia P.; DeLong, Edward F.; Stewart, Frank J.

2014-01-01

Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2–1.6 μm, >1.6 μm) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 μm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2–1.6 μm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40–70% of sequences). Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18 and 40% of all sequences, respectively). The OMZ 0.2–1.6 μm fraction was dominated (11–99%) by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 μm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveal variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion. PMID:25389417

Building Earth's Largest Library: Driving into the Future.

Science.gov (United States)

Coffman, Steve

1999-01-01

Examines the Amazon.com online bookstore as a blueprint for designing the world's largest library. Topics include selection; accessibility and convenience; quality of Web sites and search tools; personalized service; library collection development, including interlibrary loan; library catalogs and catalog records; a circulation system; costs;…

Toward sustainable harvesting of Africa's largest medicinal plant ...

African Journals Online (AJOL)

Global demand for treating prostate disorders with Prunus africana bark extract has made P. africana Africa's largest medicinal plant export. Unsustainable harvesting practices can lead to local extirpations of this multipurpose tree. Survey research targeting P. africana harvesters in a Tanzania forest reserve revealed that ...

Marine Environmental History

DEFF Research Database (Denmark)

Poulsen, Bo

2012-01-01

human society and natural marine resources. Within this broad topic, several trends and objectives are discernable. The essay argue that the so-called material marine environmental history has its main focus on trying to reconstruct the presence, development and environmental impact of past fisheries......This essay provides an overview of recent trends in the historiography of marine environmental history, a sub-field of environmental history which has grown tremendously in scope and size over the last c. 15 years. The object of marine environmental history is the changing relationship between...... and whaling operations. This ambition often entails a reconstruction also of how marine life has changed over time. The time frame rages from Paleolithicum to the present era. The field of marine environmental history also includes a more culturally oriented environmental history, which mainly has come...

Massive Mortality of a Planktivorous Seabird in Response to a Marine Heatwave: A Citizen Science Case-study

Science.gov (United States)

Jones, T.; Parrish, J.; MacCready, P.; Peterson, W. T.; Bjorkstedt, E.; Bond, N. A.; Ballance, L. T.; Bowes, V.; Hipfner, J. M.; Lindquist, K.; Lindsey, J.; Nevins, H. M.; Burgess, H. K.; Robertson, R.; Roletto, J.; Wilson, L.; Joyce, T. W.; Harvey, J.

2017-12-01

Citizen science data collection is a powerful tool for documenting mass mortality events, as they often occur without warning and can be extensive in space, precluding standard methods of data collection. The Coastal Observation and Seabird Survey Team (COASST) is one such citizen science program that specializes in the collection of information on beachcast seabird abundance and identity. Using the COASST dataset, in combination with federal monitoring data and novel modeling techniques, we investigated the 2014/15 mass mortality event of Cassin's Auklets (Ptychoramphus aleuticus), a small zooplanktivorous seabird, that occurred during the largest marine heatwave (MHW) ever recorded - the NE Pacific MHW of 2014-2016. Estimated at 275,000-530,000 birds, or 11% of the global adult population, and spanning 2,000 km of the North American Pacific coastline, this marine bird die-off is among the largest ever recorded. Carcass deposition followed an effective reduction in the energy content of zooplankton, coincident with the loss of cold-water foraging habitat caused by the intrusion of the NE Pacific MHW. Models examining interannual variability in effort-controlled carcass abundance (2001-2014) identified the biomass of lipid-poor zooplankton as the primary predictor of increased carcass abundance, suggesting that the relative abundance of smaller, lipid-poor zooplankton is a strong predictor of Cassin's Auklets overwinter survival. Furthermore, dispersing Cassin's Auklets were likely compressed into a nearshore band of upwelled water, and ultimately died from starvation following the shift in zooplankton composition associated with the onshore transport of the NE Pacific MHW. The information regarding the magnitude of this event, as well as its causal mechanism, comes as a direct result of rigorous data collection by citizen science volunteers, demonstrating that citizen science can, and does, contribute to our understanding of how climate change is altering marine

Kabob report. Pt. 3. Chevron plant largest in Canada

Energy Technology Data Exchange (ETDEWEB)

1971-01-18

Canada's largest fully integrated primary natural- gas processing and sulfur recovery plant is heading for physical completion by mid-summer of 1971. The Ralph M. Parsons Construction Co. of Canada Ltd., contractor for the S. Kaybob Beaverhill Lake Unit No. 3 gas-processing plant, to be operated by Chevron Standard Ltd., estimates completion by June 30. After that the $80 million complex will have tests and running in time. With any reasonable luck, it should be fully on stream by late summer. Preliminary construction on the 200-acre site started in Jan. 1969 with clearing and contouring of the main plant and sulfur storage sites. Initial rough grading started in the early summer, after spring breakup was over. Delivery of most of the big items was made by rail because the local secondary roads were inadequate for them. Concrete has been a large item. The contractor has its own batch plant on the site for the estimated 28,000 cu yd which will be needed for the whole job. Dominating the construction site from the start has been the high sulfur plant stack, first of the major items to be finished. It will serve to dispose of effluent from the largest sulfur recovery unit in Canada. It is 465 ft high, one of the largest in Alberta, and a significant contribution to pollution control and environmental protection.

Pretreatment of textile dyeing wastewater using an anoxic baffled reactor.

Science.gov (United States)

Kong, Huoliang; Wu, Huifang

2008-11-01

A study on pretreatment of textile dyeing wastewater was carried out using an anoxic baffled reactor (ABR) at wastewater temperatures of 5-31.1 degrees C. When hydraulic retention time (HRT) was 8h, the color of outflow of ABR was only 40 times at 5 degrees C and it could satisfy the professional discharge standard (grade-1) of textile and dyeing industry of China (GB4287-92). The total COD removal efficiency of ABR was 34.6%, 47.5%, 50.0%, 53.3%, 54.7% and 58.1% at 5, 9.7, 14.9, 19.7, 23.5 and 31.1 degrees C, respectively. Besides, after the wastewater being pre-treated by ABR when HRT was 6h and 8h, the BOD5/COD value rose from 0.30 of inflow to 0.46 of outflow and from 0.30 of inflow to 0.40 of outflow, respectively. Experimental results indicated that ABR was a very feasible process to decolorize and pre-treat the textile dyeing wastewater at ambient temperature. Moreover, a kinetic simulation of organic matter degradation in ABR at six different wastewater temperatures was carried through. The kinetic analysis showed the organic matter degradation was a first-order reaction. The reaction activation energy was 19.593 kJ mol(-1) and the temperature coefficient at 5-31.1 degrees C was 1.028.

Diversity and Variability of Geoporphyrins and Chlorins During Cretaceous Oceanic Anoxic Event II.

Science.gov (United States)

Junium, C. K.; Mawson, D. H.; Arthur, M. A.; Keely, B. J.

2005-12-01

Geoporphyrins and chlorins are biomarkers that result from the transformation of tetrapyrroles including chlorophylls, bacteriochlorophylls and haems. The transformation reactions are initiated in the water column and sediments during early diagenesis and are dependent on a range of variables including, but not limited to water column redox state, burial conditions, and time. Geoporphyrins and chlorins can retain structural characteristics that allow unambiguous assignment of precursor structures and source organisms making their utility in paleoenvironmental studies extraordinary where such information is preserved. Black shales from Oceanic Anoxic Event II (OAE II, Cenomanian-Turonian Boundary) of ODP Leg 207 present a unique opportunity for investigating the variations in the tetrapyrrole record in very well preserved sediments across a globally significant biogeochemcal event. Identification and structural assignment of tetrapyrroles in this study were achieved by a combination of high-performance-liquid-chromatography (HPLC)/diode-array-detection (DAD) and liquid chromatography-mass spectrometry (LC-MSn) on acetone extracts. Stratigraphic variations in geoporphyrin compounds occur through OAE II. The relative proportions of metallated vs. free-base (metal free) porphyrins vary throughout the sequence, favoring free-base porphyrins during the height of the anoxic event. The greater proportion of free-base porphyrins associated with more extensive reducing conditions is consistent with metal ion limitation during euxinia. For example, vanadyl porphyrins become much less abundant during the peak of the event suggesting that the oceanic inventory of V was sequestered in black shales and unavailable. Preliminary characterization of the tetrapyrroles through OAE II of ODP Leg 207, Demerara Rise, reveals a wide range of geoporphyrins and chlorins. Notably, positive identification of chlorins, the geologically unstable intermediates between highly reactive

The non-consumptive value of selected marine species at Table Mountain National Park: An exploratory study

Directory of Open Access Journals (Sweden)

Melville Saayman

2014-03-01

Full Text Available This exploratory study aimed to determine firstly the non-consumptive value of five marine species (whales, the Great White shark, penguins, dolphins and seals and secondly the socio-demographic and behavioural variables that influence willingness to pay to see these species. This was achieved by means of a structured questionnaire survey conducted at Table Mountain National Park, the largest urban national park in South Africa. The data consisted of 319 fully-completed questionnaires. These were analysed using factor analyses and Ordinary Least Squares (OLS regression analysis. The results showed that the variables influencing willingness to pay differed from species to species, with the largest differences being found in behavioural rather than socio-demographic variables. In showing how much respondents were willing to pay to see the various species and which species they preferred, the results also highlighted the non-consumptive value of the species.

Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

Energy Technology Data Exchange (ETDEWEB)

Furdek, Martina; Mikac, Nevenka [Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Bueno, Maite; Tessier, Emmanuel; Cavalheiro, Joana [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France); Monperrus, Mathilde, E-mail: mathilde.monperrus@univ-pau.fr [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France)

2016-04-15

Highlights: • Limiting step in OTC degradation in sediments is their desorption into porewater. • TBT persistence in contaminated sediments increases in sediments rich in organic matter. • DBT does not accumulate in sediments as degradation product of TBT. • TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days. • PhTs degradation is slower than BuTs degradation in oxic porewaters. - Abstract: This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9 ± 0.1 and 9.1 ± 0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.

Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

International Nuclear Information System (INIS)

Furdek, Martina; Mikac, Nevenka; Bueno, Maite; Tessier, Emmanuel; Cavalheiro, Joana; Monperrus, Mathilde

2016-01-01

Highlights: • Limiting step in OTC degradation in sediments is their desorption into porewater. • TBT persistence in contaminated sediments increases in sediments rich in organic matter. • DBT does not accumulate in sediments as degradation product of TBT. • TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days. • PhTs degradation is slower than BuTs degradation in oxic porewaters. - Abstract: This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9 ± 0.1 and 9.1 ± 0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.

The impact of electrogenic sulfide oxidation on elemental cycling and solute fluxes in coastal sediment

NARCIS (Netherlands)

Rao, A.M.F.; Malkin, S.Y.; Hidalgo-Martinez, S.; Meysman, Filip

2016-01-01

Filamentous sulfide oxidizing cable bacteria are capable of linking the oxidation of free sulfide in deep anoxic layers of marine sediments to the reduction of oxygen or nitrate in surface sediments by conducting electrons over centimeter-scale distances. Previous studies have shown that this newly

Stability of phosphorus species in seawater

Digital Repository Service at National Institute of Oceanography (India)

DileepKumar, M.; Somasundar, K.; Rajendran, A.

Relative stabilities of various oxidation states, oxyacids and dissolved inorganic complexes of phosphorus in anoxic and oxic marine environments are elucidated. H sub(3) PO sub(2)/P super(0) and H sub(2) PO sub(2)/p super(0) are the strong reducing...

The mid-Cretaceous North Atlantic nutrient trap: black shales and OAEs

NARCIS (Netherlands)

Trabucho Alexandre, J.; Tuenter, E.; Henstra, G.A.; Zwan, C.J. van der; Wal, R.S.W. van de; Dijkstra, H.A.; Boer, P.L. de

2010-01-01

Organic-rich sediments are the salient marine sedimentation product in the mid-Cretaceous of the ocean basins formed in the Mesozoic. Oceanic anoxic events (OAEs) are discrete and particularly organic-rich intervals within these mid-Cretaceous organic-rich sequences and are defined by pronounced

Jurassic carbonate microfacies, sea-level changes and the Toarcian anoxic event in the Tethys Himalaya (South Tibet)

Science.gov (United States)

Han, Zhong; Hu, Xiumian; Garzanti, Eduardo

2016-04-01

Detailed microfacies analysis of carbonate rocks from the Tingri and Nyalam areas of South Tibet allowed us to reconstruct the evolution of sedimentary environments during the Early to Middle Jurassic. Based on texture, sedimentary structure, grain composition and fossil content of about 500 thin sections, 17 microfacies overall were identified, and three evolutionary stages were defined. Stage 1 (Rhaetian?-lower Sinemurian Zhamure Formation) was characterized by siliciclastic and mixed siliciclastic-carbonate sedimentation on a barrier shore environment, stage 2 (upper Sinemurian-Pliensbachian Pupuga Formation) by high-energy grainstones with rich benthic faunas thriving on a carbonate platform, and stage 3 (Toarcian-lower Bajocian Nieniexiongla Formation) by low-energy mudstones intercalated with frequent storm layers on a carbonate ramp. Besides, Carbon isotope analyses (δ13Ccarb and δ13Corg) were performed on the late Pliensbachian-early Toarcian interval, and the organic matter recorded a pronounced stepped negative excursion -4.5‰ corresponding to characteristics of the early Toarcian oceanic anoxic event globally, which began just below the stage 2-stage 3 facies shifting boundary. The comparison between the Tethys Himalaya (South Tibet) and the tropical/subtropical zones of the Western Tethys and Panthalassa was carried out to discuss the factors controlling sedimentary evolution. The change from stage 1 to stage 2 was possibly induced by sea-level rise, when the Tibetan Tethys Himalaya was located at tropical/subtropical latitudes in suitable climatic and ecological conditions for carbonate sedimentation. The abrupt change from stage 2 to stage 3 is interpreted as a consequence of the early Toarcian oceanic anoxic event, accompanied by obvious carbon-isotope negative excursion and sea-level rise. The failed recovery from the carbonate crisis in the early Bajocian, with continuing deposition on a low-energy carbonate ramp, is ascribed to the tectonic

Upgrade and modernization of the six largest HPPs in Macedonia

International Nuclear Information System (INIS)

Hadzievska, M.

2002-01-01

In 1998, Electric Power Company of Macedonia and the International Bank for Development and Reconstruction, started the Power System Improvement Project a part of which is the Project for rehabilitation of the six largest Hydro Power Plants (HPPs) in the Republic of Macedonia. The six largest Hydro Power Plants (HPP Vrutok, HPP Raven, HPP Globocica, HPP Tikves and HPP Spilje and HPP Vrben) represent 91% of the country's hydropower capacity. The rehabilitation program is divided in five parts (contracts) and covers the refurbishment of: turbine runners, turbine and generator bearings, governors, inlet valves; butterfly valves, including accessories and control systems; generators, excitation system and voltage regulation; control system, protection and LV auxiliaries; switch gears and control gears in 220 kV, 110 kV and 35 kV substations. At the moment, only the implementation of switch gears has started, the first phase is already finished, and 50 % of the rehabilitation works for HPP Vrutok, the largest HPP, has been finished. With the realization of this project, greater hydropower production is expected. It also expected that HPPs will become a more vital part of the Macedonian power system

Microbial Mineralization of cis-Dichloroethene and Vinyl Chloride as a Component of Natural Attenuation of Chloroethene Contaminants under Conditions Identified in the Field as Anoxic

Science.gov (United States)

2012-01-01

16 2. cis-DCE mineralization kinetics under hypoxic and anoxic conditions .............................17 Conversion Factors Inch/Pound...situ conditions. Vmax is influenced by micro- bial biomass , metabolic activity, and the availability of nutri- ents and substrates that support...were incapable of growth at atmospheric oxygen levels (Morris 1976). Enzymatic defenses against oxygen radicals have been documented 20 Microbial

Coupled Mo-U abundances and isotopes in a small marine euxinic basin: Constraints on processes in euxinic basins

Science.gov (United States)

Bura-Nakić, Elvira; Andersen, Morten B.; Archer, Corey; de Souza, Gregory F.; Marguš, Marija; Vance, Derek

2018-02-01

Sedimentary molybdenum (Mo) and uranium (U) abundances, as well as their isotope systematics, are used to reconstruct the evolution of the oxygenation state of the surface Earth from the geological record. Their utility in this endeavour must be underpinned by a thorough understanding of their behaviour in modern settings. In this study, Mo-U concentrations and their isotope compositions were measured in the water column, sinking particles, sediments and pore waters of the marine euxinic Lake Rogoznica (Adriatic Sea, Croatia) over a two year period, with the aim of shedding light on the specific processes that control Mo-U accumulation and isotope fractionations in anoxic sediment. Lake Rogoznica is a 15 m deep stratified sea-lake that is anoxic and euxinic at depth. The deep euxinic part of the lake generally shows Mo depletions consistent with near-quantitative Mo removal and uptake into sediments, with Mo isotope compositions close to the oceanic composition. The data also, however, show evidence for periodic additions of isotopically light Mo to the lake waters, possibly released from authigenic precipitates formed in the upper oxic layer and subsequently processed through the euxinic layer. The data also show evidence for a small isotopic offset (∼0.3‰ on 98Mo/95Mo) between particulate and dissolved Mo, even at highest sulfide concentrations, suggesting minor Mo isotope fractionation during uptake into euxinic sediments. Uranium concentrations decrease towards the bottom of the lake, where it also becomes isotopically lighter. The U systematics in the lake show clear evidence for a dominant U removal mechanism via diffusion into, and precipitation in, euxinic sediments, though the diffusion profile is mixed away under conditions of increased density stratification between an upper oxic and lower anoxic layer. The U diffusion-driven precipitation is best described with an effective 238U/235U fractionation of +0.6‰, in line with other studied euxinic

Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators.

Science.gov (United States)

Pimiento, Catalina; Balk, Meghan A

2015-06-01

The extinct shark Carcharocles megalodon is one of the largest marine apex predators ever to exist. Nonetheless, little is known about its body-size variations through time and space. Here, we studied the body-size trends of C. megalodon through its temporal and geographic range to better understand its ecology and evolution. Given that this species was the last of the megatooth lineage, a group of species that shows a purported size increase through time, we hypothesized that C. megalodon also displayed this trend, increasing in size over time and reaching its largest size prior to extinction. We found that C. megalodon body-size distribution was left-skewed (suggesting a long-term selective pressure favoring larger individuals), and presented significant geographic variation (possibly as a result of the heterogeneous ecological constraints of this cosmopolitan species) over geologic time. Finally, we found that stasis was the general mode of size evolution of C. megalodon (i.e., no net changes over time), contrasting with the trends of the megatooth lineage and our hypothesis. Given that C. megalodon is a relatively long-lived species with a widely distributed fossil record, we further used this study system to provide a deep-time perspective to the understanding of the body-size trends of marine apex predators. For instance, our results suggest that (1) a selective pressure in predatory sharks for consuming a broader range of prey may favor larger individuals and produce left-skewed distributions on a geologic time scale; (2) body-size variations in cosmopolitan apex marine predators may depend on their interactions with geographically discrete communities; and (3) the inherent characteristics of shark species can produce stable sizes over geologic time, regardless of the size trends of their lineages.

World's third-largest producer of nuclear power. Japan in need of energy

International Nuclear Information System (INIS)

Anon.

2008-01-01

Japan is the third largest oil consumer in the world behind the United States and China, and the second largest net importer of oil. Japan boasts one of the largest economies in the world. The country continues to experience a moderate economic recovery that began in 2003, following a decade of economic stagnation. Japan's real gross domestic product (GDP) grew by 2.5% in 2005 and 2.3% in 2004. The modest upturn over the last few years reflects higher business confidence in Japan, a surge in export demand led by exports to China, and robust consumer spending. Unemployment in Japan fell to 4.4% in 2005, down from an early 2003 peak of 5.5%. Japan has virtually no domestic oil or natural gas reserves, and in 2005 was the second largest net importer of crude oil in the world. Despite the country's dearth of hydrocarbon resources, Japanese companies have actively pursued upstream oil and natural gas projects overseas. Japan remains one of the major exporters of energy-sector capital equipment, and Japanese companies provide engineering, construction, and project management services for energy projects. (orig.)

Large-Scale Trade in Legally Protected Marine Mollusc Shells from Java and Bali, Indonesia.

Science.gov (United States)

Nijman, Vincent; Spaan, Denise; Nekaris, K Anne-Isola

2015-01-01

Tropical marine molluscs are traded globally. Larger species with slow life histories are under threat from over-exploitation. We report on the trade in protected marine mollusc shells in and from Java and Bali, Indonesia. Since 1987 twelve species of marine molluscs are protected under Indonesian law to shield them from overexploitation. Despite this protection they are traded openly in large volumes. We collected data on species composition, origins, volumes and prices at two large open markets (2013), collected data from wholesale traders (2013), and compiled seizure data by the Indonesian authorities (2008-2013). All twelve protected species were observed in trade. Smaller species were traded for Java and Bali, but the trade involves networks stretching hundreds of kilometres throughout Indonesia. Wholesale traders offer protected marine mollusc shells for the export market by the container or by the metric ton. Data from 20 confiscated shipments show an on-going trade in these molluscs. Over 42,000 shells were seized over a 5-year period, with a retail value of USD700,000 within Indonesia; horned helmet (Cassis cornuta) (>32,000 shells valued at USD500,000), chambered nautilus (Nautilus pompilius) (>3,000 shells, USD60,000) and giant clams (Tridacna spp.) (>2,000 shells, USD45,000) were traded in largest volumes. Two-thirds of this trade was destined for international markets, including in the USA and Asia-Pacific region. We demonstrated that the trade in protected marine mollusc shells in Indonesia is not controlled nor monitored, that it involves large volumes, and that networks of shell collectors, traders, middlemen and exporters span the globe. This impedes protection of these species on the ground and calls into question the effectiveness of protected species management in Indonesia; solutions are unlikely to be found only in Indonesia and must involve the cooperation of importing countries.

Large-Scale Trade in Legally Protected Marine Mollusc Shells from Java and Bali, Indonesia

Science.gov (United States)

Nijman, Vincent; Spaan, Denise; Nekaris, K. Anne-Isola

2015-01-01

Background Tropical marine molluscs are traded globally. Larger species with slow life histories are under threat from over-exploitation. We report on the trade in protected marine mollusc shells in and from Java and Bali, Indonesia. Since 1987 twelve species of marine molluscs are protected under Indonesian law to shield them from overexploitation. Despite this protection they are traded openly in large volumes. Methodology/Principal Findings We collected data on species composition, origins, volumes and prices at two large open markets (2013), collected data from wholesale traders (2013), and compiled seizure data by the Indonesian authorities (2008–2013). All twelve protected species were observed in trade. Smaller species were traded for trade involves networks stretching hundreds of kilometres throughout Indonesia. Wholesale traders offer protected marine mollusc shells for the export market by the container or by the metric ton. Data from 20 confiscated shipments show an on-going trade in these molluscs. Over 42,000 shells were seized over a 5-year period, with a retail value of USD700,000 within Indonesia; horned helmet (Cassis cornuta) (>32,000 shells valued at USD500,000), chambered nautilus (Nautilus pompilius) (>3,000 shells, USD60,000) and giant clams (Tridacna spp.) (>2,000 shells, USD45,000) were traded in largest volumes. Two-thirds of this trade was destined for international markets, including in the USA and Asia-Pacific region. Conclusions/Significance We demonstrated that the trade in protected marine mollusc shells in Indonesia is not controlled nor monitored, that it involves large volumes, and that networks of shell collectors, traders, middlemen and exporters span the globe. This impedes protection of these species on the ground and calls into question the effectiveness of protected species management in Indonesia; solutions are unlikely to be found only in Indonesia and must involve the cooperation of importing countries. PMID:26717021

Biogeochemical controls on the oxygen, nitrogen and sulfur distributions in the water column of Golfo Dulce: an anoxic basin on the Pacific coast of Costa Rica revisited

International Nuclear Information System (INIS)

Ferdelman, Timothy G.; Thamdrup, Bo; Canfield, Donald E.; Noehr Glud, Ronnie; Kuever, Jan; Lillebaek, Rolf; Birger Ramsing, Niels; Wawer, Cathrin

2006-01-01

Chemical distributions, respiration rates, and bacterial distributions were measured in 1994 in the water column and sediments of a small, tropical, anoxic basin (Golfo Dulce, Pacific coast of Costa Rica) to examine the biogeochemical controls on anoxia, sulfide, dissolved inorganic nitrogen, and organic carbon consumption. As reported previously, the deepest 100 m of the water column were anoxic, and sulfide concentrations in the bottom waters were less than 7 μM and then only transiently. Both free-swimming sulfide-oxidizing bacteria and Beggiatoa sp. (containing large vacuoles) were observed in the anoxic bottom waters or at the sediment-water interface. Aerobic respiration dominated the decomposition of organic matter in the surface waters and pycnocline, whereas sulfate reduction was principally restricted to the sediments. Bacteria were distributed in discrete zones and exhibited the highest densities where oxygen decreased below 1 μM around 100 m depth, and near the sediment-water interface. The sub-oxic, sub-pycnocline water column was characterized by a dissolved inorganic nitrogen (DIN) deficit of 2.9 mole m -2 . With a water residence time of 35 - 57 d, estimated from a salt balance, this deficit corresponded to a DIN loss of 51 - 85 mmol m -2 d -1 , comparable to the sub-pycnocline oxygen consumption. Sulfide in the water column was maintained at low concentrations by frequent inputs of oxygenated water from the Pacific Ocean. Sulfide production in the sediments due to bacterial sulfate reduction was scavenged by frequent deposition of iron-rich turbidites. Based on 210 Pb distributions, the most recent emplacement of a turbidite in the basin sediments was determined to have occurred between 1989 and 1992. (author) [es

Marine polar steroids

International Nuclear Information System (INIS)

Stonik, Valentin A

2001-01-01

Structures, taxonomic distribution and biological activities of polar steroids isolated from various marine organisms over the last 8-10 years are considered. The peculiarities of steroid biogenesis in the marine biota and their possible biological functions are discussed. Syntheses of some highly active marine polar steroids are described. The bibliography includes 254 references.

Size-distributions of n-alkanes, PAHs and hopanes and their sources in the urban, mountain and marine atmospheres over East Asia

Directory of Open Access Journals (Sweden)

Z. Wang

2009-11-01

Full Text Available Size-segregated (9 stages n-alkanes, polycyclic aromatic hydrocarbons (PAHs and hopanes in the urban (Baoji city in inland China, mountain (Mt. Tai in east coastal China and marine (Okinawa Island, Japan atmospheres over East Asia were studied using a GC/MS technique. Ambient concentrations of n-alkanes (1698±568 ng m−3 in winter and 487±145 ng m−3 in spring, PAHs (536±80 and 161±39 ng m−3, and hopanes (65±24 and 20±2.4 ng m−3 in the urban air are 1–2 orders of magnitude higher than those in the mountain aerosols and 2–3 orders of magnitude higher than those in the marine samples. Mass ratios of n-alkanes, PAHs and hopanes clearly demonstrate coal-burning emissions as their major source. Size distributions of fossil fuel derived n-alkane, PAHs and hopanes were found to be unimodal in most cases, peaking at 0.7–1.1 μm size. In contrast, plant wax derived n-alkanes presented a bimodal distribution with two peaks at the sizes of 0.7–1.1 μm and >4.7 μm in the summer mountain and spring marine samples. Among the three types of samples, geometric mean diameter (GMD of the organics in fine mode (<2.1 μm was found to be smallest (av. 0.63 μm in spring for the urban samples and largest (1.01 μm for the marine samples, whereas the GMD in coarse mode (≥2.1 μm was found to be smallest (3.48 μm for the marine aerosols and largest (4.04 μm for the urban aerosols. The fine mode GMDs of the urban and mountain samples were larger in winter than in spring and summer. Moreover, GMDs of 3- and 4-ring PAHs were larger than those of 5- and 6-ring PAHs in the three types of atmospheres. Such differences in GMDs can be interpreted by the repartitioning of organic compounds and the coagulation and hygroscopic growth of particles during a long-range transport from the inland continent to the marine area, as well as the difference in their sources among the three regions.

NAFTA: The World's Largest Trading Zone Turns 20

Science.gov (United States)

Ferrarini, Tawni Hunt; Day, Stephen

2014-01-01

Everyone under the age of 20 who has grown up in North America has lived in the common market created by NAFTA--the North American Free Trade Agreement. In a zone linking the United States, Canada, and Mexico, most goods and investments flow freely across borders to users, consumers, and investors. In 1994, NAFTA created the largest relatively…

Contrasting oxygen dynamics in the freshwater isoetid Lobelia dortmanna and the marine seagrass Zostera marina

DEFF Research Database (Denmark)

Sand-Jensen, Kaj; Pedersen, Ole; Binzer, Thomas

2005-01-01

BACKGROUND: and Aims Submerged plants possess well-developed aerenchyma facilitating intra-plant gas-phase diffusion of O2 to below-ground tissues, which are usually buried in anoxic sediments. However, aquatic habitats differ in terms of O2 fluctuations in the water column and in O2 consumption...... roots and low O2 consumption of sediments means that sediment, aerenchyma and water are important O2 sources for respiration during the following night, while Z. marina relies on the water column as the sole source of O2 because its sediments are anoxic. These differences between L. dortmanna and Z...

An assessment of natural product discovery from marine (sensu strictu) and marine-derived fungi

Science.gov (United States)

Overy, David P.; Bayman, Paul; Kerr, Russell G.; Bills, Gerald F.

2014-01-01

The natural products community has been investigating secondary metabolites from marine fungi for several decades, but when one attempts to search for validated reports of new natural products from marine fungi, one encounters a literature saturated with reports from ‘marine-derived’ fungi. Of the 1000+ metabolites that have been characterized to date, only approximately 80 of these have been isolated from species from exclusively marine lineages. These metabolites are summarized here along with the lifestyle and habitats of their producing organisms. Furthermore, we address some of the reasons for the apparent disconnect between the stated objectives of discovering new chemistry from marine organisms and the apparent neglect of the truly exceptional obligate marine fungi. We also offer suggestions on how to reinvigorate enthusiasm for marine natural products discovery from fungi from exclusive marine lineages and highlight the need for critically assessing the role of apparently terrestrial fungi in the marine environment. PMID:25379338

Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes

Science.gov (United States)

Miller, L.G.; Oremland, R.S.

2008-01-01

Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress. ?? 2008 US Government.

Some Environmental Consequences of Large Igneous Provinces

Science.gov (United States)

Coffin, M. F.

2009-12-01

The formation of large igneous provinces (LIPs)—continental flood basalts, ‘volcanic’ margins, and oceanic plateaus—may impact the atmosphere, oceans, and biosphere by rapidly releasing huge amounts of particulates, magmatic volatiles (CO2, SO2, Cl, F, etc.), and potentially volatiles (CO2, CH4, SO2, etc.) from intruded sediments (e.g., carbonates, organic-rich shales, evaporites). A key factor affecting the magnitude of volatile release is whether eruptions are subaerial or marine; hydrostatic pressure inhibits vesiculation and degassing of relatively soluble volatile components (H2O, S, Cl, F) in deep water submarine eruptions, although low solubility components (CO2, noble gases) are mostly degassed even at abyssal depths. Directly or indirectly, such injections may cause changes in the atmosphere/ocean system that can lead to perturbations of atmosphere/ocean chemistry, circulation, ecology, and biological productivity. These changes can be global in extent, particularly if environmental conditions were at or near a threshold state or tipping point. LIPs may have been responsible for some of the most dramatic and rapid changes in the global environment. For example, between ~145 and ~50 Ma, the global ocean was characterized by chemical and isotopic variations (especially in C and Sr isotope ratios, trace metal concentrations, and biocalcification), relatively high temperatures, high relative sea level, episodic deposition of black shales (oceanic anoxic events), high production of hydrocarbons, mass extinctions of marine organisms, and radiations of marine flora and fauna. Temporal correlations between the intense pulses of igneous activity associated with LIP formation and environmental changes suggest more than pure coincidence. The 1783-84 eruption of Laki on Iceland provides the only historical record of the type of volcanism that constructs transient LIPs. Although Laki produced a basaltic lava flow representing only ~1% of the volume of a typical

Desulfuromonas thiophila sp. nov., a new obligately sulfur-reducing bacterium from anoxic freshwater sediment.

Science.gov (United States)

Finster, K; Coates, J D; Liesack, W; Pfennig, N

1997-07-01

A mesophilic, acetate-oxidizing, sulfur-reducing bacterium, strain NZ27T, was isolated from anoxic mud from a freshwater sulfur spring. The cells were ovoid, motile, and gram negative. In addition to acetate, the strain oxidized pyruvate, succinate, and fumarate. Sulfur flower could be replaced by polysulfide as an electron acceptor. Ferric nitrilotriacetic acid was reduced in the presence of pyruvate; however, this reduction did not sustain growth. These phenotypic characteristics suggested that strain NZ27T is affiliated with the genus Desulfuromonas. A phylogenetic analysis based on the results of comparative 16S ribosomal DNA sequencing confirmed that strain NZ27T belongs to the Desulfuromonas cluster in the recently proposed family "Geobacteracea" in the delta subgroup of the Proteobacteria. In addition, the results of DNA-DNA hybridization studies confirmed that strain NZ27T represents a novel species. Desulfuromonas thiophila, a name tentatively used in previous publication, is the name proposed for strain NZ27T in this paper.

Effect of Free Ammonia, Free Nitrous Acid, and Alkalinity on the Partial Nitrification of Pretreated Pig Slurry, Using an Alternating Oxic/Anoxic SBR

Directory of Open Access Journals (Sweden)

Marisol Belmonte

2017-01-01

Full Text Available The effect of free ammonia (NH3 or FA, free nitrous acid (HNO2 or FNA, and total alkalinity (TA on the performance of a partial nitrification (PN sequencing batch reactor (SBR treating anaerobically pretreated pig slurry was studied. The SBR was operated under alternating oxic/anoxic (O/A conditions and was fed during anoxic phases. This strategy allowed using organic matter to partially remove nitrite (NO2- and nitrate (NO3- generated during oxic phases. The desired NH4+ to NO2- ratio of 1.3 g N/g N was obtained when an Ammonium Loading Rate (ALR of 0.09 g NH4+-N/L·d was applied. The system was operated at a solid retention time (SRT of 15–20 d and dissolved oxygen (DO levels higher than 3 mg O2/L during the whole operational period. PN mainly occurred caused by the inhibitory effect of FNA on nitrite oxidizing bacteria (NOB. Once HNO2 concentration was negligible, NH4+ was fully oxidized to NO3- in spite of the presence of FA. The use of biomass acclimated to ammonium as inoculum avoided a possible effect of FA on NOB activity.

The Environmental Responsibility of the World’s Largest Banks

Directory of Open Access Journals (Sweden)

Ryszawska Bożena

2018-03-01

Full Text Available Sustainability transition is changing the role and function of banks, specially their products and services also in relation to stakeholders. Banks are one of the main actors supporting the transition to sustainable economy. The purpose of this study is to emphasise the role of world’s largest banks in that process. Banks are slowly responding to the new demand of sustainability and responsibility, and they try to align with it. The paper is based on an overview of the world’s five largest banks that employ corporate social responsibility (CSR reporting standards, together with detailed enumeration of pro-environmental activities included in the reports. The first section of this paper presents the most popular approaches to the problem at hand, as reported in professional literature. Section two presents the characteristics of the CSR actions in banks. The third section discusses the environmental actions of the biggest banks in Global Reporting Initiative (GRI reporting the most popular standard for reporting non-financial information. And the last part of the paper presents the conclusions resulting from the article. The research was conducted using a variety of sources, such as scientific articles, statistical data, CSR reports of the world’s largest banks, as well reporting principles and standard disclosures. The basic method used in the process of writing was a critical analysis of literature and reports concerning the CSR reporting standards, environmental responsibilities of different kinds of entities, as well as own observations based on special reports of banks. In the article, also the analysis of financial market data, induction method and comparison method have been used. The main conclusions of the analysis of the CSR reports disclosed by the world’s largest banks confirm all three of the theses presented in the article. The findings suggest that the banks under study can be regarded as environmentally responsible

Environmental Impact Assessment in the marine environment: A comparison of legal frameworks

Energy Technology Data Exchange (ETDEWEB)

Guerra, Flávia, E-mail: f.c.diasguerra@vu.nl [Institute for Environmental Studies, VU University Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands); Liga para a Protecção da Natureza, 1500-124 Lisboa (Portugal); Grilo, Catarina [Liga para a Protecção da Natureza, 1500-124 Lisboa (Portugal); Pedroso, Nuno M. [Laboratório de Ecologia Isotópica — CENA, Universidade de São Paulo, Caixa Postal 96, 13416-000 Piracicaba, SP (Brazil); Centre for Ecology, Evolution and Environmental Changes — cE3c, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Cabral, Henrique [MARE — Marine and Environmental Sciences Centre, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal)

2015-11-15

Environmental Impact Assessment (EIA) is a well-established practice in most developed countries, even though its application to projects in the marine environment is at a much earlier stage of development. We use the Portuguese example to address marine EIA legislation since its exclusive economic zone (EEZ) is currently the third largest in the European Union and its EIA legislation does not require various offshore activities with potentially negative environmental impacts to undergo EIA before being licensed. This paper aims to determine whether three types of projects implemented within Portuguese maritime zones – artificial reefs using sunken ships, hydrocarbon prospecting and wave-energy generation – would benefit from application of an appropriately designed EIA. We have conducted a structured review of EIA legal provisions from seven other countries, and considered whether a full EIA was required for each project type. Consequently, 12 Environmental Impact Statements (EIS) have been compared to identify patterns of (dis)similarity across countries and project types. Additionally, we identified key descriptors and predicted impacts for each project type referred to in their EIS. The main conclusion is that ultimately all three projects would benefit from mandatory EIA in Portugal. This paper is relevant for countries with large maritime areas and underdeveloped marine EIA legislation, helping improve international policy-making relating to these three types of marine projects. - Highlights: • EIA is not mandatory for some project types developed in Portuguese maritime zones. • Artificial reefs, oil&gas prospecting and wave-energy licensing differ in 8 countries. • EIA should be mandatory in Portugal for artificial reefs and oil&gas prospecting. • However, an AEInc approach is enough for wave-energy projects in Portugal. • Findings could be extended to other EU countries with extensive maritime zones.

Environmental Impact Assessment in the marine environment: A comparison of legal frameworks

International Nuclear Information System (INIS)

Guerra, Flávia; Grilo, Catarina; Pedroso, Nuno M.; Cabral, Henrique

2015-01-01

Environmental Impact Assessment (EIA) is a well-established practice in most developed countries, even though its application to projects in the marine environment is at a much earlier stage of development. We use the Portuguese example to address marine EIA legislation since its exclusive economic zone (EEZ) is currently the third largest in the European Union and its EIA legislation does not require various offshore activities with potentially negative environmental impacts to undergo EIA before being licensed. This paper aims to determine whether three types of projects implemented within Portuguese maritime zones – artificial reefs using sunken ships, hydrocarbon prospecting and wave-energy generation – would benefit from application of an appropriately designed EIA. We have conducted a structured review of EIA legal provisions from seven other countries, and considered whether a full EIA was required for each project type. Consequently, 12 Environmental Impact Statements (EIS) have been compared to identify patterns of (dis)similarity across countries and project types. Additionally, we identified key descriptors and predicted impacts for each project type referred to in their EIS. The main conclusion is that ultimately all three projects would benefit from mandatory EIA in Portugal. This paper is relevant for countries with large maritime areas and underdeveloped marine EIA legislation, helping improve international policy-making relating to these three types of marine projects. - Highlights: • EIA is not mandatory for some project types developed in Portuguese maritime zones. • Artificial reefs, oil&gas prospecting and wave-energy licensing differ in 8 countries. • EIA should be mandatory in Portugal for artificial reefs and oil&gas prospecting. • However, an AEInc approach is enough for wave-energy projects in Portugal. • Findings could be extended to other EU countries with extensive maritime zones

International marine and aviation bunker fuel. Trends, ranking of countries and comparison with national CO2 emission

International Nuclear Information System (INIS)

Olivier, J.G.J.; Peters, J.A.H.W.

1999-01-01

This report summarises and characterises fuel consumption and associated CO2 emissions from international transport based on energy statistics compiled by the International Energy Agency (IEA). Shares in 1990 and 1970-1995 trends in national and global bunker fuel consumption and associated CO2 emissions are analysed for marine and air transport. Also, the global total of international transport emissions are compared with national emissions and domestic transport emissions. During the last 25 years the average global annual increase was for marine bunkers about 0.8% and for aviation emissions about 3.3%. Annual variations per country of marine bunker fuel use larger than of aviation fuel use, sometimes more than 50%. However, the distinction between fuel use for domestic and for international aviation is more difficult to monitor. The dominant fuel in marine bunker fuel consumption is residual fuel oil ('heavy fuel oil'). The share of diesel oil has slowly increased from 11% in 1970 to 20% in 1990. Aviation fuels sold are predominantly jet fuel ('jet kerosene'). The small share of aviation gasoline is slowly decreasing: from about 4% in 1970 to 1.3% in 1990. Carbon dioxide emissions from combustion of international marine bunker fuels and aviation contributed in 1990 globally about 1.8% and 2.4% expressed as percentage of global total anthropogenic emissions (excluding deforestation). However, aviation emissions include an unknown part of domestic aviation. When comparing with total transport emissions, then international transport has a share of 20%. For both marine and aviation bunker fuel, the Top-10 of largest consuming countries account for about 2/3 of the global total; the Top-25 countries cover already 85% or more of global total CO2 emissions

Carotenoids in Marine Animals

Science.gov (United States)

Maoka, Takashi

2011-01-01

Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine animal carotenoids from natural product chemistry, metabolism, food chain, and chemosystematic viewpoints, and also describe new structural carotenoids isolated from marine animals over the last decade. PMID:21566799

Marine Biomedicine

Science.gov (United States)

Bang, Frederik B.

1977-01-01

Describes early scientific research involving marine invertebrate pathologic processes that may have led to new insights into human disease. Discussed are inquiries of Metchnikoff, Loeb, and Cantacuzene (immunolgic responses in sea stars, horseshoe crabs, and marine worms, respectively). Describes current research stemming from these early…

Marine Biology

Science.gov (United States)

Dewees, Christopher M.; Hooper, Jon K.

1976-01-01

A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

Active Marine Station Metadata

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Active Marine Station Metadata is a daily metadata report for active marine bouy and C-MAN (Coastal Marine Automated Network) platforms from the National Data...

Characterizing Marine Soundscapes.

Science.gov (United States)

Erbe, Christine; McCauley, Robert; Gavrilov, Alexander

2016-01-01

The study of marine soundscapes is becoming widespread and the amount of data collected is increasing rapidly. Data owners (typically academia, industry, government, and defense) are negotiating data sharing and generating potential for data syntheses, comparative studies, analyses of trends, and large-scale and long-term acoustic ecology research. A problem is the lack of standards and commonly agreed protocols for the recording of marine soundscapes, data analysis, and reporting that make a synthesis and comparison of results difficult. We provide a brief overview of the components in a marine soundscape, the hard- and software tools for recording and analyzing marine soundscapes, and common reporting formats.

Statistics of the largest sunspot and facular areas per solar cycle

International Nuclear Information System (INIS)

Willis, D.M.; Kabasakal Tulunay, Y.

1979-01-01

The statistics of extreme values is used to investigate the statistical properties of the largest areas sunspots and photospheric faculae per solar cycle. The largest values of the synodic-solar-rotation mean areas of umbrae, whole spots and faculae, which have been recorded for nine solar cycles, are each shown to comply with the general form of the extreme value probability function. Empirical expressions are derived for the three extreme value populations from which the characteristic statistical parameters, namely the mode, median, mean and standard deviation, can be calculated for each population. These three extreme value populations are also used to find the expected ranges of the extreme areas in a group of solar cycles as a function of the number of cycles in the group. The extreme areas of umbrae and whole spots have a dispersion comparable to that found by Siscoe for the extreme values of sunspot number, whereas the extreme areas of faculae have a smaller dispersion which is comparable to that found by Siscoe for the largest geomagnetic storm per solar cycle. The expected range of the largest sunspot area per solar cycle for a group of one hundred cycles appears to be inconsistent with the existence of the prolonged periods of sunspot minima that have been inferred from the historical information on solar variability. This inconsistency supports the contention that there are temporal changes of solar-cycle statistics during protracted periods of sunspot minima (or maxima). Indeed, without such temporal changes, photospheric faculae should have been continually observable throughout the lifetime of the Sun. (orig.)

Fishing down the largest coral reef fish species.

Science.gov (United States)

Fenner, Douglas

2014-07-15

Studies on remote, uninhabited, near-pristine reefs have revealed surprisingly large populations of large reef fish. Locations such as the northwestern Hawaiian Islands, northern Marianas Islands, Line Islands, U.S. remote Pacific Islands, Cocos-Keeling Atoll and Chagos archipelago have much higher reef fish biomass than islands and reefs near people. Much of the high biomass of most remote reef fish communities lies in the largest species, such as sharks, bumphead parrots, giant trevally, and humphead wrasse. Some, such as sharks and giant trevally, are apex predators, but others such as bumphead parrots and humphead wrasse, are not. At many locations, decreases in large reef fish species have been attributed to fishing. Fishing is well known to remove the largest fish first, and a quantitative measure of vulnerability to fishing indicates that large reef fish species are much more vulnerable to fishing than small fish. The removal of large reef fish by fishing parallels the extinction of terrestrial megafauna by early humans. However large reef fish have great value for various ecological roles and for reef tourism. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Multivariate Largest Lyapunov Exponent as an Age-Related Metric of Quiet Standing Balance

Directory of Open Access Journals (Sweden)

Kun Liu

2015-01-01

Full Text Available The largest Lyapunov exponent has been researched as a metric of the balance ability during human quiet standing. However, the sensitivity and accuracy of this measurement method are not good enough for clinical use. The present research proposes a metric of the human body’s standing balance ability based on the multivariate largest Lyapunov exponent which can quantify the human standing balance. The dynamic multivariate time series of ankle, knee, and hip were measured by multiple electrical goniometers. Thirty-six normal people of different ages participated in the test. With acquired data, the multivariate largest Lyapunov exponent was calculated. Finally, the results of the proposed approach were analysed and compared with the traditional method, for which the largest Lyapunov exponent and power spectral density from the centre of pressure were also calculated. The following conclusions can be obtained. The multivariate largest Lyapunov exponent has a higher degree of differentiation in differentiating balance in eyes-closed conditions. The MLLE value reflects the overall coordination between multisegment movements. Individuals of different ages can be distinguished by their MLLE values. The standing stability of human is reduced with the increment of age.

Crash testing the largest experiment on Earth

OpenAIRE

Cauchi, Marija

2015-01-01

Under Europe lies a 27 km tunnel that is both the coldest and hottest place on Earth. The Large Hadron Collider (LHC) has already found out what gives mass to all the matter in the Universe. It is now trying to go even deeper into what makes up everything we see around us. Dr Marija Cauchi writes about her research that helped protect this atom smasher from itself. Photography by Jean Claude Vancell. http://www.um.edu.mt/think/crash-testing-the-largest-experiment-on-earth/

Carotenoids in Marine Animals

OpenAIRE

Maoka, Takashi

2011-01-01

Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine a...

Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

Directory of Open Access Journals (Sweden)

Anja Kamp

2016-11-01

Full Text Available Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations > 60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2-3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations.

Hundred years of genetic structure in a sediment revived diatom population

DEFF Research Database (Denmark)

Haernstroem, Karolina; Ellegaard, Marianne; Andersen, Thorbjørn Joest

2011-01-01

This paper presents research on the genetic structure and diversity of populations of a common marine protist and their changes over time. The bloom-forming diatom Skeletonema marinoi was used as a model organism. Strains were revived from anoxic discrete layers of a 210Pb-dated sediment core...

Microbial Precipitation of Cr(III)-Hydroxide and Se(0) Nanoparticles During Anoxic Bioreduction of Cr(VI)- and Se(VI)-Contaminated Water.

Science.gov (United States)

Kim, Yumi; Oh, Jong-Min; Roh, Yul

2017-04-01

This study examined the microbial precipitations of Cr(III)-hydroxide and Se(0) nanoparticles during anoxic bioreductions of Cr(VI) and Se(VI) using metal-reducing bacteria enriched from groundwater. Metal-reducing bacteria enriched from groundwater at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT), Daejeon, S. Korea were used. Metal reduction and precipitation experiments with the metal-reducing bacteria were conducted using Cr(VI)- and Se(VI)-contaminated water and glucose as a carbon source under an anaerobic environment at room temperature. XRD, SEM-EDX, and TEM-EDX analyses were used to characterize the mineralogy, crystal structure, chemistry, shape, and size distribution of the precipitates. The metal-reducing bacteria reduced Cr(VI) of potassium chromate (K₂CrO₄) to Cr(III) of chromium hydroxide [Cr(OH)3], and Se(VI) of sodium selenate (Na₂SeO₄) to selenium Se(0), with changes of color and turbidity. XRD, SEM-EDX, and TEM-EDX analyses revealed that the chromium hydroxide [Cr(OH)₃] was formed extracellularly with nanoparticles of 20–30 nm in size, and elemental selenium Se(0) nanoparticles had a sphere shape of 50–250 nm in size. These results show that metal-reducing bacteria in groundwater can aid or accelerate precipitation of heavy metals such as Cr(VI) and Se(VI) via bioreduction processes under anoxic environments. These results may also be useful for the recovery of Cr and Se nanoparticles in natural environments.

Marine Science

African Journals Online (AJOL)

Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ... or by any means without permission in writing from the copyright holder. ..... Journal of Chemical Engineering Research and Design 82 ... Indian Ocean Marine Science Association Technical.

Marine animal stings or bites

Science.gov (United States)

Stings - marine animals; Bites - marine animals ... Things you can do to prevent a marine animal sting or bite include: Swim near a lifeguard. Observe posted signs that may warn of danger from jellyfish or other hazardous marine life. ...

Implementing and Innovating Marine Monitoring Approaches for Assessing Marine Environmental Status

KAUST Repository

Danovaro, Roberto; Carugati, Laura; Berzano, Marco; Cahill, Abigail E.; Carvalho, Susana; Chenuil, Anne; Corinaldesi, Cinzia; Cristina, Sonia; David, Romain; Dell'Anno, Antonio; Dzhembekova, Nina; Garcé s, Esther; Gasol, Joseph M.; Goela, Priscila; Fé ral, Jean-Pierre; Ferrera, Isabel; Forster, Rodney M.; Kurekin, Andrey A.; Rastelli, Eugenio; Marinova, Veselka; Miller, Peter I.; Moncheva, Snejana; Newton, Alice; Pearman, John K.; Pitois, Sophie G.; Reñ é , Albert; Rodrí guez-Ezpeleta, Naiara; Saggiomo, Vincenzo; Simis, Stefan G. H.; Stefanova, Kremena; Wilson, Christian; Lo Martire, Marco; Greco, Silvestro; Cochrane, Sabine K. J.; Mangoni, Olga; Borja, Angel

2016-01-01

Marine environmental monitoring has tended to focus on site-specific methods of investigation. These traditional methods have low spatial and temporal resolution and are relatively labor intensive per unit area/time that they cover. To implement the Marine Strategy Framework Directive (MSFD), European Member States are required to improve marine monitoring and design monitoring networks. This can be achieved by developing and testing innovative and cost-effective monitoring systems, as well as indicators of environmental status. Here, we present several recently developed methodologies and technologies to improve marine biodiversity indicators and monitoring methods. The innovative tools are discussed concerning the technologies presently utilized as well as the advantages and disadvantages of their use in routine monitoring. In particular, the present analysis focuses on: (i) molecular approaches, including microarray, Real Time quantitative PCR (qPCR), and metagenetic (metabarcoding) tools; (ii) optical (remote) sensing and acoustic methods; and (iii) in situ monitoring instruments. We also discuss their applications in marine monitoring within the MSFD through the analysis of case studies in order to evaluate their potential utilization in future routine marine monitoring. We show that these recently-developed technologies can present clear advantages in accuracy, efficiency and cost.

Implementing and Innovating Marine Monitoring Approaches for Assessing Marine Environmental Status

KAUST Repository

Danovaro, Roberto

2016-11-23

Marine environmental monitoring has tended to focus on site-specific methods of investigation. These traditional methods have low spatial and temporal resolution and are relatively labor intensive per unit area/time that they cover. To implement the Marine Strategy Framework Directive (MSFD), European Member States are required to improve marine monitoring and design monitoring networks. This can be achieved by developing and testing innovative and cost-effective monitoring systems, as well as indicators of environmental status. Here, we present several recently developed methodologies and technologies to improve marine biodiversity indicators and monitoring methods. The innovative tools are discussed concerning the technologies presently utilized as well as the advantages and disadvantages of their use in routine monitoring. In particular, the present analysis focuses on: (i) molecular approaches, including microarray, Real Time quantitative PCR (qPCR), and metagenetic (metabarcoding) tools; (ii) optical (remote) sensing and acoustic methods; and (iii) in situ monitoring instruments. We also discuss their applications in marine monitoring within the MSFD through the analysis of case studies in order to evaluate their potential utilization in future routine marine monitoring. We show that these recently-developed technologies can present clear advantages in accuracy, efficiency and cost.

Otters, Marine

Science.gov (United States)

Estes, James A.; Bodkin, James L.; Ben-David, M.; Perrin, William F.; Würsing, Bernd; Thewissen, J.G.M.

2009-01-01

The otters (Mustelidae; Lutrinae) provide an exceptional perspective into the evolution of marine living by mammals. Most extant marine mammals (e.g. the cetaceans, pinnipeds, and sirenians) have been so highly modified by long periods of selection for life in the sea that they bear little resemblance to their terrestrial ancestors. Marine otters, in contrast, are more recent expatriates from freshwater habitats and some species still live in both environments. Contrasts among species within the otters, and among the otters, terrestrial mammals, and the more highly adapted pinnipeds and cetaceans provide powerful insights into mammalian adaptations to life in the sea (Estes, 1989). Among the marine mammals, sea otters (Enhydra lutris, Fig. 1) provide the clearest understanding of consumer-induced effects on ecosystem function. This is due in part to opportunities provided by history and in part to the relative ease with which shallow coastal systems where sea otters live can be observed and studied. Although more difficult to study than sea otters, other otter species reveal the connectivity among the marine, freshwater, and terrestrial systems. These three qualities of the otters – their comparative biology, their role as predators, and their role as agents of ecosystem connectivity – are what make them interesting to marine mammalogy.The following account provides a broad overview of the comparative biology and ecology of the otters, with particular emphasis on those species or populations that live in the sea. Sea otters are features prominently, in part because they live exclusively in the sea whereas other otters have obligate associations with freshwater and terrestrial environments (Kenyon, 1969; Riedman and Estes, 1990).

Economic Incentives, Perceptions and Compliance with Marine Turtle Egg Harvesting Regulation in Nicaragua

Directory of Open Access Journals (Sweden)

Róger Madrigal-Ballestero

2017-01-01

Full Text Available La Flor Wildlife Refuge and nearby beaches on the Pacific coast of Nicaragua are important nesting sites for various species of endangered marine turtles. However, illegal harvesting of turtle eggs threatens the survival of marine turtles. In this study, we analysed the different motivations of local villagers for complying with a ban on harvesting marine turtle eggs in a context, in which government authorities do not have the means to fully enforce existing regulations. We also analysed the effectiveness and the participation of locals in an incipient performance-based nest conservation payment programme to protect turtle eggs. The analysis of survey-based data from 180 households living in Ostional, the largest village near La Flor Wildlife Refuge, indicates remarkable socio-economic differences between harvesters and non-harvesters. Our findings suggest that harvesters are associated mainly with a lack of income from other activities and the absence of productive assets, such as land for cattle and/or agriculture. In addition, the lack of legitimacy of prevailing institutions (i.e., actual regulations also seems to perpetuate illegal harvesting. The performance-based payments programme is an effective option for protecting nests on isolated beaches, however, it is not clear if it changes harvesting behaviour overall. Normative motivations to protect the turtles are important determinants of participation in this programme, although the financial reward is also an important incentive, particularly since most participants who are egg harvesters depend on this activity as their main source of income.

Predicting Traffic Flow in Local Area Networks by the Largest Lyapunov Exponent

Directory of Open Access Journals (Sweden)

Yan Liu

2016-01-01

Full Text Available The dynamics of network traffic are complex and nonlinear, and chaotic behaviors and their prediction, which play an important role in local area networks (LANs, are studied in detail, using the largest Lyapunov exponent. With the introduction of phase space reconstruction based on the time sequence, the high-dimensional traffic is projected onto the low dimension reconstructed phase space, and a reduced dynamic system is obtained from the dynamic system viewpoint. Then, a numerical method for computing the largest Lyapunov exponent of the low-dimensional dynamic system is presented. Further, the longest predictable time, which is related to chaotic behaviors in the system, is studied using the largest Lyapunov exponent, and the Wolf method is used to predict the evolution of the traffic in a local area network by both Dot and Interval predictions, and a reliable result is obtained by the presented method. As the conclusion, the results show that the largest Lyapunov exponent can be used to describe the sensitivity of the trajectory in the reconstructed phase space to the initial values. Moreover, Dot Prediction can effectively predict the flow burst. The numerical simulation also shows that the presented method is feasible and efficient for predicting the complex dynamic behaviors in LAN traffic, especially for congestion and attack in networks, which are the main two complex phenomena behaving as chaos in networks.

MaNIDA: Insight into the German Marine Network for Integrated Data Access

Science.gov (United States)

Schäfer, Angela; Scientific MaNIDA Team

2013-04-01

The Marine Network for Integrated Data Access (MaNIDA) builds a sustainable e-Infrastructure to support discovery and re-use of data from distinct marine and earth science data providers in Germany (see ESSI1.2 and ESSI2.2). Thereby we implement the "Data Portal of German Marine Research" for coherent discovery, view, download and dissemination of aggregated content. MaNIDA receives a unique momentum from the cooperation and financial partnership between main German marine research institutes (AWI, MARUM, HZG, GEOMAR, Uni Hamburg, Uni Kiel, Uni Bremen) and the Federal Maritime and Hydrographic Agency as well as active participation in international and major EU-initiatives (ICSU, GEOSS, SeaDataNet, EMODNET, ODIP). Together with a coherent management strategy coordinated by the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, sustainability will be achieved via the long-term commitment of framework funding by the Helmholtz Association, Germany's largest scientific research organization for large-scale facilities and scientific infrastructure. Strategic Aims The installation of the "Data Portal of German Marine Research" will address the urgent demands of the German research community for reliable and easy access to marine research data at one single point of access and truth. Primary focus will be given to data derived from nationally operated research and monitoring facilities (vessels, observatories, alert systems, etc), whereby related contextual content and publications will become an integral part of the aggregation effort. For the scientific community we define responsibilities and commitments across partners while complementing existing data repositories and the new portal with well-articulated workflows from the instrument to the data product. Necessary level of quality assurance and user support will be implemented to achieve substantial enhancements in the whole lifecycle management of marine scientific data. The creation of a data

Seashore marine table quiz

OpenAIRE

Institute, Marine

2013-01-01

Develop an increasing awareness of plants and animals that live in local marine environments including the seashore, seas and oceans of Ireland. After learning all about the seashore and other marine related lessons, this quiz can be used to evaluate the student’s knowledge of the marine related living things and natural environments. The table quiz can be used as a guide, highlighting facts about the marine environment and some of the animals that live there.

Occurrence and distribution of pharmaceutically active and endocrine disrupting compounds in Singapore's marine environment: Influence of hydrodynamics and physical–chemical properties

International Nuclear Information System (INIS)

Bayen, Stéphane; Zhang, Hui; Desai, Malan Manish; Ooi, Seng Keat; Kelly, Barry C.

2013-01-01

The fate and exposure risks of pharmaceutically active compounds (PhACs) and endocrine disrupting chemicals (EDCs) in marine environments are not well-understood. In this study we developed a multi-residue analytical method for quantifying concentrations of forty target compounds in seawater from Singapore. Analyses of samples (n = 24) from eight sites showed the occurrence of several compounds, including gemfibrozil ( R ). Principal Components Analysis revealed a strong relationship between t R and contaminant concentrations. While source emissions are undoubtedly important, proximate distance to a wastewater treatment plant had little influence on concentrations. The site with the greatest t R , which exhibited the highest concentrations, is adjacent to Singapore's largest protected wetland reserve. The results highlight an important linkage between hydrodynamic behavior and contaminant exposure risks in complex coastal marine ecosystems. Highlights: •A field study of emerging contaminants in Singapore's coastal marine environment was conducted. •PhACs such as gemfibrozil, triclosan, carbamazepine and ibuprofen were frequently detected. •Site proximity to WWTP had little influence on ambient concentrations. •Contaminant concentrations were highly correlated to hydrodynamic residence time. •Coastal hydrodynamic behaviour greatly influences contaminant exposure risks. -- A field study demonstrates the influence of hydrodynamic residence time and physical–chemical properties on exposure risks of PhACs and EDCs in coastal marine ecosystems

Marine bioacoustics and technology: The new world of marine acoustic ecology

Science.gov (United States)

Hastings, Mardi C.; Au, Whitlow W. L.

2012-11-01

Marine animals use sound for communication, navigation, predator avoidance, and prey detection. Thus the rise in acoustic energy associated with increasing human activity in the ocean has potential to impact the lives of marine animals. Thirty years ago marine bioacoustics primarily focused on evaluating effects of human-generated sound on hearing and behavior by testing captive animals and visually observing wild animals. Since that time rapidly changing electronic and computing technologies have yielded three tools that revolutionized how bioacousticians study marine animals. These tools are (1) portable systems for measuring electrophysiological auditory evoked potentials, (2) miniaturized tags equipped with positioning sensors and acoustic recording devices for continuous short-term acoustical observation rather than intermittent visual observation, and (3) passive acoustic monitoring (PAM) systems for remote long-term acoustic observations at specific locations. The beauty of these breakthroughs is their direct applicability to wild animals in natural habitats rather than only to animals held in captivity. Hearing capabilities of many wild species including polar bears, beaked whales, and reef fishes have now been assessed by measuring their auditory evoked potentials. Miniaturized acoustic tags temporarily attached to an animal to record its movements and acoustic environment have revealed the acoustic foraging behavior of sperm and beaked whales. Now tags are being adapted to fishes in effort to understand their behavior in the presence of noise. Moving and static PAM systems automatically detect and characterize biological and physical features of an ocean area without adding any acoustic energy to the environment. PAM is becoming a powerful technique for understanding and managing marine habitats. This paper will review the influence of these transformative tools on the knowledge base of marine bioacoustics and elucidation of relationships between marine

Marine Jurisdiction Boundaries

Data.gov (United States)

Department of Homeland Security — The NOAA Coastal Services Center's Marine Jurisdiction dataset was created to assist in marine spatial planning and offshore alternative energy sitting. This is a...

75 FR 68605 - Marine Mammals

Science.gov (United States)

2010-11-08

...-XX23 Marine Mammals AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... permit to conduct research on marine mammals. ADDRESSES: The permit and related documents are available... applicant. The requested permit has been issued under the authority of the Marine Mammal Protection Act of...

77 FR 2512 - Marine Mammals

Science.gov (United States)

2012-01-18

...-XA905 Marine Mammals AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... Dorian Houser, Ph.D., National Marine Mammal Foundation, 2240 Shelter Island Drive, 200, San Diego, CA... subject permit is requested under the authority of the Marine Mammal Protection Act of 1972, as amended...

Anoxic sulfide biooxidation using nitrite as electron acceptor

International Nuclear Information System (INIS)

Mahmood, Qaisar; Zheng Ping; Cai Jing; Wu Donglei; Hu, Baolan; Li Jinye

2007-01-01

Biotechnology can be used to assess the well being of ecosystems, transform pollutants into benign substances, generate biodegradable materials from renewable sources, and develop environmentally safe manufacturing and disposal processes. Simultaneous elimination of sulfide and nitrite from synthetic wastewaters was investigated using a bioreactor. A laboratory scale anoxic sulfide-oxidizing (ASO) reactor was operated for 135 days to evaluate the potential for volumetric loading rates, effect of hydraulic retention time (HRT) and substrate concentration on the process performance. The maximal sulfide and nitrite removal rates were achieved to be 13.82 and 16.311 kg/(m 3 day), respectively, at 0.10 day HRT. The process can endure high sulfide concentrations, as the sulfide removal percentage always remained higher than 88.97% with influent concentration up to 1920 mg/L. Incomplete sulfide oxidation took place due to lower consumed nitrite to sulfide ratios of 0.93. It also tolerated high nitrite concentration up to 2265.25 mg/L. The potential achieved by decreasing HRT at fixed substrate concentration is higher than that by increasing substrate concentration at fixed HRT. The process can bear short HRT of 0.10 day but careful operation is needed. Nitrite conversion was more sensitive to HRT than sulfide conversion when HRT was decreased from 1.50 to 0.08 day. Stoichiometric analyses and results of batch experiments show that major part of sulfide (89-90%) was reduced by nitrite while some autooxidation (10-11%) was resulted from presence of small quantities of dissolved oxygen in the influent wastewater. There was ammonia amassing in considerably high amounts in the bioreactor when the influent nitrite concentration reached above 2265.25 mg/L. High ammonia concentrations (200-550 mg/L) in the bioreactor contributed towards the overall inhibition of the process. Present biotechnology exhibits practical value with a high potential for simultaneous removal of nitrite

77 FR 17033 - Taking and Importing Marine Mammals: Taking Marine Mammals Incidental to Navy's Training...

Science.gov (United States)

2012-03-23

... take marine mammals by harassment incidental to its training activities at the Gulf of Mexico (GOMEX... Importing Marine Mammals: Taking Marine Mammals Incidental to Navy's Training Activities at the Gulf of Mexico Range Complex AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric...

In vitro selection of bacteria with potential for use as probiotics in marine shrimp culture

Directory of Open Access Journals (Sweden)

Felipe do Nascimento Vieira

2013-08-01

Full Text Available The objective of this work was to isolate strains of lactic acid bacteria with probiotic potential from the digestive tract of marine shrimp (Litopenaeus vannamei, and to carry out in vitro selection based on multiple characters. The ideotype (ideal proposed strain was defined by the highest averages for the traits maximum growth velocity, final count of viable cells, and inhibition halo against nine freshwater and marine pathogens, and by the lowest averages for the traits duplication time and resistance of strains to NaCl (1.5 and 3%, pH (6, 8, and 9, and biliary salts (5%. Mahalanobis distance (D² was estimated among the evaluated strains, and the best ones were those with the shortest distances to the ideotype. Ten bacterial strains were isolated and biochemically identified as Lactobacillus plantarum (3, L. brevis (3, Weissella confusa (2, Lactococcus lactis (1, and L. delbrueckii (1. Lactobacillus plantarum strains showed a wide spectrum of action and the largest inhibition halos against pathogens, both Gram-positive and negative, high growth rate, and tolerance to all evaluated parameters. In relation to ideotype, L. plantarum showed the lowest Mahalanobis (D² distance, followed by the strains of W. confusa, L. brevis, L. lactis, and L. delbrueckii. Among the analyzed bacterial strains, those of Lactobacillus plantarum have the greatest potential for use as a probiotic for marine shrimp.

Marine biodiversity and fishery sustainability.

Science.gov (United States)

Shao, Kwang-Tsao

2009-01-01

Marine fish is one of the most important sources of animal protein for human use, especially in developing countries with coastlines. Marine fishery is also an important industry in many countries. Fifty years ago, many people believed that the ocean was so vast and so resilient that there was no way the marine environment could be changed, nor could marine fishery resources be depleted. Half a century later, we all agree that the depletion of fishery resources is happening mainly due to anthropogenic factors such as overfishing, habitat destruction, pollution, invasive species introduction, and climate change. Since overfishing can cause chain reactions that decrease marine biodiversity drastically, there will be no seafood left after 40 years if we take no action. The most effective ways to reverse this downward trend and restore fishery resources are to promote fishery conservation, establish marine-protected areas, adopt ecosystem-based management, and implement a "precautionary principle." Additionally, enhancing public awareness of marine conservation, which includes eco-labeling, fishery ban or enclosure, slow fishing, and MPA (marine protected areas) enforcement is important and effective. In this paper, we use Taiwan as an example to discuss the problems facing marine biodiversity and sustainable fisheries.

Marine electrical practice

CERN Document Server

Watson, G O

1991-01-01

Marine Engineering Series: Marine Electrical Practice, Sixth Edition focuses on changes in the marine industry, including the application of programmable electronic systems, generators, and motors. The publication first ponders on insulation and temperature ratings of equipment, protection and discrimination, and AC generators. Discussions focus on construction, shaft-drive generators, effect of unbalanced loading, subtransient and transient reactance, protection discrimination, fault current, measurement of ambient air temperature, and basis of machine ratings. The text then examines AC switc

Mariners Weather Log

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Mariners Weather Log (MWL) is a publication containing articles, news and information about marine weather events and phenomena, worldwide environmental impact...

Marine Genomics: A clearing-house for genomic and transcriptomic data of marine organisms

Directory of Open Access Journals (Sweden)

Trent Harold F

2005-03-01

Full Text Available Abstract Background The Marine Genomics project is a functional genomics initiative developed to provide a pipeline for the curation of Expressed Sequence Tags (ESTs and gene expression microarray data for marine organisms. It provides a unique clearing-house for marine specific EST and microarray data and is currently available at http://www.marinegenomics.org. Description The Marine Genomics pipeline automates the processing, maintenance, storage and analysis of EST and microarray data for an increasing number of marine species. It currently contains 19 species databases (over 46,000 EST sequences that are maintained by registered users from local and remote locations in Europe and South America in addition to the USA. A collection of analysis tools are implemented. These include a pipeline upload tool for EST FASTA file, sequence trace file and microarray data, an annotative text search, automated sequence trimming, sequence quality control (QA/QC editing, sequence BLAST capabilities and a tool for interactive submission to GenBank. Another feature of this resource is the integration with a scientific computing analysis environment implemented by MATLAB. Conclusion The conglomeration of multiple marine organisms with integrated analysis tools enables users to focus on the comprehensive descriptions of transcriptomic responses to typical marine stresses. This cross species data comparison and integration enables users to contain their research within a marine-oriented data management and analysis environment.

Increased Intracranial Pressure during Hemodialysis in a Patient with Anoxic Brain Injury

Directory of Open Access Journals (Sweden)

Anton Lund

2017-01-01

Full Text Available Dialysis disequilibrium syndrome (DDS is a serious neurological complication of hemodialysis, and patients with acute brain injury are at increased risk. We report a case of DDS leading to intracranial hypertension in a patient with anoxic brain injury and discuss the subsequent dialysis strategy. A 13-year-old girl was admitted after prolonged resuscitation from cardiac arrest. Computed tomography (CT revealed an inferior vena cava aneurysm and multiple pulmonary emboli as the likely cause. An intracranial pressure (ICP monitor was inserted, and, on day 3, continuous renal replacement therapy (CRRT was initiated due to acute kidney injury, during which the patient developed severe intracranial hypertension. CT of the brain showed diffuse cerebral edema. CRRT was discontinued, sedation was increased, and hypertonic saline was administered, upon which ICP normalized. Due to persistent hyperkalemia and overhydration, ultrafiltration and intermittent hemodialysis were performed separately on day 4 with a small dialyzer, low blood and dialysate flow, and high dialysate sodium content. During subsequent treatments, isolated ultrafiltration was well tolerated, whereas hemodialysis was associated with increased ICP necessitating frequent pauses or early cessation of dialysis. In patients at risk of DDS, hemodialysis should be performed with utmost care and continuous monitoring of ICP should be considered.

Increased Intracranial Pressure during Hemodialysis in a Patient with Anoxic Brain Injury.

Science.gov (United States)

Lund, Anton; Damholt, Mette B; Strange, Ditte G; Kelsen, Jesper; Møller-Sørensen, Hasse; Møller, Kirsten

2017-01-01

Dialysis disequilibrium syndrome (DDS) is a serious neurological complication of hemodialysis, and patients with acute brain injury are at increased risk. We report a case of DDS leading to intracranial hypertension in a patient with anoxic brain injury and discuss the subsequent dialysis strategy. A 13-year-old girl was admitted after prolonged resuscitation from cardiac arrest. Computed tomography (CT) revealed an inferior vena cava aneurysm and multiple pulmonary emboli as the likely cause. An intracranial pressure (ICP) monitor was inserted, and, on day 3, continuous renal replacement therapy (CRRT) was initiated due to acute kidney injury, during which the patient developed severe intracranial hypertension. CT of the brain showed diffuse cerebral edema. CRRT was discontinued, sedation was increased, and hypertonic saline was administered, upon which ICP normalized. Due to persistent hyperkalemia and overhydration, ultrafiltration and intermittent hemodialysis were performed separately on day 4 with a small dialyzer, low blood and dialysate flow, and high dialysate sodium content. During subsequent treatments, isolated ultrafiltration was well tolerated, whereas hemodialysis was associated with increased ICP necessitating frequent pauses or early cessation of dialysis. In patients at risk of DDS, hemodialysis should be performed with utmost care and continuous monitoring of ICP should be considered.

76 FR 76949 - Marine Mammals

Science.gov (United States)

2011-12-09

...-XR52 Marine Mammals AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric.... 14534 is requested under the authority of the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations governing the taking and importing of marine mammals (50 CFR part 216...

77 FR 14352 - Marine Mammals

Science.gov (United States)

2012-03-09

...-XB065 Marine Mammals AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations governing the taking and importing of marine mammals (50 CFR part 216), the Endangered Species Act of 1973, as amended...

75 FR 77616 - Marine Mammals

Science.gov (United States)

2010-12-13

.... 14334] Marine Mammals AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations governing the taking and importing of marine mammals (50 CFR part 216), the Endangered Species Act of 1973, as amended...

State and perspectives in the sphere of marine waste: data from Russian Far East

Science.gov (United States)

Korshenko, Ekaterina; Tyurina, Elena; Kravchenko, Alla; Glotova, Elena; Sergeeva, Olesya; Korshenko, Alexander; Nesterova, Olga; Tregubova, Valentina; Semal, Viktoriia; Derbentseva, Alla; Purtova, Lyudmila; Kostenkov, Nikolay

2016-04-01

Today, pollution of seas and coastal areas by waste is one of the most important environmental issues recognized at international scale. This problem consists in negative effect on marine flora and fauna, and as global experience shows, requires cooperation of government, business sector and civil society to overcome it. A large number of studies confirm the serious impact of marine litter: sea inhabitants easily take pieces of plastic as something edible, these particles can get into stomach of fish, and then through the food chain into humans. Barnes highlighted the potential threat due to the appearance of alien species. Brown studied the entanglement of marine creatures at nets that eventually leads to the extinction of certain species and destruction of underwater fauna. According to the UN every year about one million seabirds, one hundred thousand turtles and other marine mammals entangle in fishing gear and die. The problem of marine waste is also relevant for Primorsky Krai of the Russian Federation. Within the project "Ocean without borders" in 2014 monitoring of Japan Sea pollution was carried out: 2,67 hectares of 16 coasts were investigated, more than 500 kg of litter were collected and studied, among which 363 grams of marine debris was an average per 100 m2, and a number of collected waste units was about 143. It should be noted that the largest proportion of collected litter is plastic which is followed by glass and ceramics. Today, marine debris in Primorsky Krai is disposed at specially organized landfills, where the air is contaminated by sulfur dioxide and various harmful organic compounds. It may lead not only to the deterioration of the environment, but also to the infectious diseases, the pollution of groundwater and soil. Therefore, an environmental entrepreneurship can be considered as a solution for the problem. One of the first who dared to use ocean litter is the studio Swain (UK), which proposed the project of transforming collected

MarineCadastre.gov

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — MarineCadastre.gov is a marine information system that provides authoritative ocean data, offshore planning tools, and technical support to the offshore renewable...

Marine actinobacteria associated with marine organisms and their potentials in producing pharmaceutical natural products.

Science.gov (United States)

Valliappan, Karuppiah; Sun, Wei; Li, Zhiyong

2014-09-01

Actinobacteria are ubiquitous in the marine environment, playing an important ecological role in the recycling of refractory biomaterials and producing novel natural products with pharmic applications. Actinobacteria have been detected or isolated from the marine creatures such as sponges, corals, mollusks, ascidians, seaweeds, and seagrass. Marine organism-associated actinobacterial 16S rRNA gene sequences, i.e., 3,003 sequences, deposited in the NCBI database clearly revealed enormous numbers of actinobacteria associated with marine organisms. For example, RDP classification of these sequences showed that 112 and 62 actinobacterial genera were associated with the sponges and corals, respectively. In most cases, it is expected that these actinobacteria protect the host against pathogens by producing bioactive compounds. Natural products investigation and functional gene screening of the actinobacteria associated with the marine organisms revealed that they can synthesize numerous natural products including polyketides, isoprenoids, phenazines, peptides, indolocarbazoles, sterols, and others. These compounds showed anticancer, antimicrobial, antiparasitic, neurological, antioxidant, and anti-HIV activities. Therefore, marine organism-associated actinobacteria represent an important resource for marine drugs. It is an upcoming field of research to search for novel actinobacteria and pharmaceutical natural products from actinobacteria associated with the marine organisms. In this review, we attempt to summarize the present knowledge on the diversity and natural products production of actinobacteria associated with the marine organisms, based on the publications from 1991 to 2013.

Geochemistry of a marine phosphate deposit: A signpost to phosphogenesis

Science.gov (United States)

Piper, David Z.; Perkins, R.B.

2014-01-01

The Permian age Phosphoria Formation in southeastern Idaho and adjoining states represents possibly the largest marine phosphate deposit in the world. The Meade Peak Member, which contains the highest concentrations and amount of carbonate fluorapatite in the formation, was not significantly altered by mechanical reworking during deposition or subsequently by chemical weathering. Thus, its present composition reflects properties of the Phosphoria Sea that were critical to its accumulation and possibly to the accumulation of most major marine phosphate deposits. These properties included the chemistry of the water column, the hydrography, and the level of primary productivity. Calculated accumulation rates of the PO43− and trace nutrients – Cd, Cu, Ni, and Zn – recorded a dynamic upwelling rate of c.30 m year−1 that supported primary productivity of 2g C m−2day−1. High accumulation rates of the hydrogenous redox-sensitive trace metals – Cr, Mo, U, and V – reflect bottom-water redox conditions that were dominantly suboxic, maintained by a balance between the oxidation of ~ 8% of the organic detritus that settled out of the photic zone and advection of bottom water with a residence time of c.10 years. A limited flux into the basin of siliciclastic lithogenous debris contributed further to elevated concentrations of the seawater-derived sediment fractions.

76 FR 41463 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a...

Science.gov (United States)

2011-07-14

... requirements, many marine animals may need to remain in areas where they are exposed to chronic stimuli... Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine... Atmospheric Administration (NOAA), National Marine Fisheries Service (NMFS). ACTION: Notice; proposed...

Using Telepresence to Connect and Engage Classes and the Public in the Exploration of Tamu Massif, the World's Largest Single Volcano

Science.gov (United States)

Nanez-James, S. E.; Sager, W.

2016-02-01

Research published in 2013 showed that TAMU Massif, the largest mountain in the Shatsky Rise oceanic plateau, located approximately 1500 kilometers east of Japan, is the "World's Largest Single Volcano." This claim garnered widespread public interest and wonder concerning how something so big could remain so mysterious in the 21st century. This disconnect highlights the fact that oceans are still widely unexplored, especially the middle of the deep ocean. Because there is so much interest in TAMU Massif, a diverse outreach team lead by chief scientist Dr. William Sager from the University of Houston in partnership with the Texas State Aquarium and the Schmidt Ocean Institute (SOI) conducted a multifaceted ship-to-shore outreach project that included secondary school students, formal and informal educators, university students and professors, the aquarium and museum audience, and the general public. The objective was to work in conjunction with SOI and various other partners, including the Texas Regional Collaborative, the Aquarium of the Pacific, and the Houston Museum of Natural Science, to promote science and ocean literacy while inspiring future scientists - especially those from underserved and underrepresented groups - through ocean connections. Participants were connected through live ship-to-shore distance learning broadcasts of ongoing marine research and discovery of TAMU Massif aboard the R/V Falkor, allowing audiences to participate in real-time research and apply real world science to curriculum in the classrooms. These ship-to-shore presentations connected to existing curriculums and standards, lessons, and career interests of the students and educators with special teacher events and professional development workshops conducted from aboard the R/V Falkor.

[Analysis on sustainable development of marine economy in Jiangsu Province based on marine ecological footprint correction model].

Science.gov (United States)

Yang, Shan; Wang, Yu-ting

2011-03-01

Based on the theories and methods of ecological footprint, the concept of marine ecological footprint was proposed. According to the characteristics of marine environment in Jiangsu Province, five sub-models of marine ecological footprints, including fishery, transporation, marine engineering construction, marine energy, and tidal flat, were constructed. The equilibrium factors of the five marine types were determined by using improved entropy method, and the marine footprints and capacities in Jiangsu Province from 2000 to 2008 were calculated and analyzed. In 2000-2008, the marine ecology footprint per capita in Jiangsu Province increased nearly seven times, from 36.90 hm2 to 252.94 hm2, and the ecological capacity per capita grew steadily, from 105.01 hm2 to 185.49 hm2. In 2000, the marine environment in the Province was in a state of ecological surplus, and the marine economy was in a weak sustainable development state. Since 2004, the marine ecological environment deteriorated sharply, with ecological deficit up to 109660.5 hm2, and the sustainability of marine economy declined. The high ecological footprint of fishery was the main reason for the ecological deficit. Tidal flat was the important reserve resource for the sustainable development of marine economy in Jiangsu Province.

Marine Education Knowledge Inventory.

Science.gov (United States)

Hounshell, Paul B.; Hampton, Carolyn

This 35-item, multiple-choice Marine Education Knowledge Inventory was developed for use in upper elementary/middle schools to measure a student's knowledge of marine science. Content of test items is drawn from oceanography, ecology, earth science, navigation, and the biological sciences (focusing on marine animals). Steps in the construction of…

Factors controlling the compositional variations among the marine and non-marine black shales from Egypt

Energy Technology Data Exchange (ETDEWEB)

Baioumy, Hassan M. [Central Metallurgical R and D Institute, PO Box 87 Helwan, Cairo (Egypt); Ismael, Ismael S. [Faculty of Science, Suez Canal University, Suez (Egypt)

2010-07-01

Non-marine (Jurassic) and marine (Cretaceous) black shales from Egypt were subjected to mineralogical and geochemical analyses to examine the controlling factors of their compositional variations. Non-marine black shales are composed of kaolinite and quartz with traces of gypsum, illite, calcite, feldspars, and dolomite, while marine black shales from the Red Sea area are composed of smectite, kaolinite, quartz, calcite, and dolomite with traces of feldspars. Abu Tartur marine black shales are composed of smectite and quartz with traces of feldspars and gypsum. Non-marine black shales show considerably higher Nb, Ta, Hf, and Zr contents and Th/Yb ratios compared to the marine black shales. On the other hand, marine black shales show considerably higher Cr, V, and Zn contents with positive correlations between these elements and organic carbon (C{sub org.}){sub .} Red Sea black shales have higher Ni/Co, V/Cr, and U/Al ratios. Chondrite normalized values of the medium and heavy rare earth elements (MREEs and HREEs, respectively) are higher in the non-marine black shales compared to the marine black shales. Pyrite from non-marine black shales is characterized by high positive {delta}{sup 34}S isotope values (average of + 9.3 permille). Pyrite from Red Sea black shales has low negative {delta}{sup 34}S values (average of -16.7 permille), pyrite from black shales of the lower member of the Duwi Formation has positive {delta}{sup 34}S values (average of 5.8 permille), while pyrite from marine black shales of the middle member has negative {delta}{sup 34}S values (average of -0.83 permille). Source area composition, weathering conditions, depositional environments, and type of organic matter are considered to be the probable controlling factors of these variations. The more felsic constituents in the source area of non-marine black shales is responsible for the relatively high Nb, Ta, Hf, and Zr contents and Th/Yb ratio. Relatively high kaolinite contents and Chemical

Lagisza, world's largest CFB boiler, begins commercial operation

Energy Technology Data Exchange (ETDEWEB)

Nuortimo, K. [Foster Wheeler, Varkaus (Finland)

2010-04-15

Early operating experience with the Lagisza circulating fluidised bed (CFB) boiler in Poland - the world's largest such boiler to date, and also the first one with supercritical steam conditions - has been positive. 3 figs., 4 tabs.

Bathymetric terrain model of the Atlantic margin for marine geological investigations

Science.gov (United States)

Andrews, Brian D.; Chaytor, Jason D.; ten Brink, Uri S.; Brothers, Daniel S.; Gardner, James V.; Lobecker, Elizabeth A.; Calder, Brian R.

2016-01-01

A bathymetric terrain model of the Atlantic margin covering almost 725,000 square kilometers of seafloor from the New England Seamounts in the north to the Blake Basin in the south is compiled from existing multibeam bathymetric data for marine geological investigations. Although other terrain models of the same area are extant, they are produced from either satellite-derived bathymetry at coarse resolution (ETOPO1), or use older bathymetric data collected by using a combination of single beam and multibeam sonars (Coastal Relief Model). The new multibeam data used to produce this terrain model have been edited by using hydrographic data processing software to maximize the quality, usability, and cartographic presentation of the combined 100-meter resolution grid. The final grid provides the largest high-resolution, seamless terrain model of the Atlantic margin..

78 FR 30870 - Nomination of Existing Marine Protected Areas to the National System of Marine Protected Areas

Science.gov (United States)

2013-05-23

... Marine Protected Areas to the National System of Marine Protected Areas AGENCY: National Marine Protected...) invited federal, state, commonwealth, and territorial marine protected area (MPA) programs with... of Marine Protected Areas of the United States (Framework), developed in response to Executive Order...

Temporal properties of seismicity and largest earthquakes in SE Carpathians

Directory of Open Access Journals (Sweden)

S. Byrdina

2006-01-01

Full Text Available In order to estimate the hazard rate distribution of the largest seismic events in Vrancea, South-Eastern Carpathians, we study temporal properties of historical and instrumental catalogues of seismicity. First, on the basis of Generalized Extreme Value theory we estimate the average return period of the largest events. Then, following Bak et al. (2002 and Corral (2005a, we study scaling properties of recurrence times between earthquakes in appropriate spatial volumes. We come to the conclusion that the seismicity is temporally clustered, and that the distribution of recurrence times is significantly different from a Poisson process even for times largely exceeding corresponding periods of foreshock and aftershock activity. Modeling the recurrence times by a gamma distributed variable, we finally estimate hazard rates with respect to the time elapsed from the last large earthquake.

Plastics in the Marine Environment.

Science.gov (United States)

Law, Kara Lavender

2017-01-03

Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence-albeit limited-of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

Plastics in the Marine Environment

Science.gov (United States)

Law, Kara Lavender

2017-01-01

Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence—albeit limited—of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

Biosurfactants from marine microorganisms

Directory of Open Access Journals (Sweden)

Suppasil Maneerat

2005-11-01

Full Text Available Biosurfactants are the surface-active molecules synthesized by microorganisms. With the advantage of environmental compatibility, the demand for biosurfactants has been steadily increasing and may eventually replace their chemically synthesized counterparts. Marine biosurfactants produced by some marine microorganisms have been paid more attention, particularly for the bioremediation of the sea polluted by crude oil. This review describes screening of biosurfactant-producing microorganisms, the determination of biosurfactant activity as well as the recovery of marine surfactant. The uses of marine biosurfactants for bioremediation are also discussed.

A hydrological budget (2002-2008) for a large subtropical wetland ecosystem indicates marine groundwater discharge accompanies diminished freshwater flow

Science.gov (United States)

Saha, Amartya K.; Moses, Christopher S.; Price, Rene M.; Engel, Victor; Smith, Thomas J.; Anderson, Gordon

2012-01-01

Water budget parameters are estimated for Shark River Slough (SRS), the main drainage within Everglades National Park (ENP) from 2002 to 2008. Inputs to the water budget include surface water inflows and precipitation while outputs consist of evapotranspiration, discharge to the Gulf of Mexico and seepage losses due to municipal wellfield extraction. The daily change in volume of SRS is equated to the difference between input and outputs yielding a residual term consisting of component errors and net groundwater exchange. Results predict significant net groundwater discharge to the SRS peaking in June and positively correlated with surface water salinity at the mangrove ecotone, lagging by 1 month. Precipitation, the largest input to the SRS, is offset by ET (the largest output); thereby highlighting the importance of increasing fresh water inflows into ENP for maintaining conditions in terrestrial, estuarine, and marine ecosystems of South Florida.

Impact of Bioreduction on Remobilization of Adsorbed Cadmium on Iron Minerals in Anoxic Condition.

Science.gov (United States)

Ghorbanzadeh, Nasrin; Lakzian, Amir; Halajnia, Akram; Choi, Ui-Kyu; Kim, Ki-Hyun; Kim, Jong-Oh; Kurade, Mayur; Jeon, Byong-Hun

2017-06-01

  The impact of bioreduction on the remobilization of adsorbed cadmium Cd(II) on minerals, including hematite, goethite, and two iron(III)-rich clay minerals nontronites (NAU-1 and NAU-2) under anoxic conditions was investigated. Langmuir isotherm equation better described the sorption of Cd(II) onto the all minerals. The maximum adsorption capacity was 6.2, 18.1, 3.6, and 4 mg g-1 for hematite, goethite, NAU-1 and NAU-2, respectively. The desorption of Cd(II) was due to the production of Fe(II) as a result of bioreduction of structural Fe(III) in the minerals by Shewanella putrefaciens. The bioreduction of Cd(II)-loaded Fe(III) minerals was negligible during the initial 5 days followed by a rapid increase up to 20 days. The amount of Cd(II) in solution phase at the end of 30 days increased up to 0.07 mmol L-1 for hematite, NAU-1, and NAU-2 and 0.02 mmol L-1 for goethite. The X-ray diffraction study showed negligible changes in bioreduced minerals phases.

75 FR 54095 - Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Seismic Survey in...

Science.gov (United States)

2010-09-03

... Marine Mammals Incidental to Specified Activities; Low- Energy Marine Seismic Survey in the Eastern... low-energy marine seismic survey. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is... funding provided by the National Science Foundation, a low-energy marine seismic survey. NMFS reviewed SIO...

How does Australia's largest dolphin-watching industry affect the behaviour of a small and resident population of Indo-Pacific bottlenose dolphins?

Science.gov (United States)

Steckenreuter, Andre; Möller, Luciana; Harcourt, Robert

2012-04-30

The small, genetically distinct population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Port Stephens, New South Wales (NSW), is the target of the largest dolphin-watching industry in Australia and is located within the Port Stephens - Great Lakes Marine Park that was created in 2005. The effects of this industry have been identified as of significant management importance by the Marine Parks Authority NSW. Accordingly, the impact of commercial dolphin-watching boats was investigated from boat-based surveys from August 2008 to August 2009. Presence of dolphin-watching boats altered both the dolphins' behavioural states and activity budgets. Dolphins spent 66.5% less time feeding and 44.2% less time socialising, spent four times more milling, and were never observed to rest in the presence of dolphin-watching boats. Moreover, dolphin groups were more cohesive during dolphin-watching boat encounters and dolphins tended to avoid tour boats. These effects were exacerbated as the number of boats increased and the distance from boats decreased. The rate of approach was high with boats approaching each dolphin group three times per day in winter and six times in summer. Moreover, groups of dolphins with newborns were approached closer than state regulated minimum approach distances in nine out of ten encounters. Globally, dolphin-watching industries frequent small resident groups of coastal dolphins and effects are likely to be similar. We suggest that existing controls are inadequate and that these together with additional regulations be enforced by a regular presence of authorities. We suggest no more than one dolphin-watching boat within 50 m of a group of dolphins, or 100 m if calves are present. Operating times of dolphin-watching boats should be restricted in numbers after 1 pm, i.e., during preferred foraging times for dolphins. Additionally, exclusion zones should be considered to reduce pressure on dolphins undertaking critical activities such as

Linking Marine Ecosystem Services to the North Sea’s Energy Fields in Transnational Marine Spatial Planning

Directory of Open Access Journals (Sweden)

Christina Vogel

2018-06-01

Full Text Available Marine spatial planning temporally and spatially allocates marine resources to different users. The ecosystem approach aims at optimising the social and economic benefits people derive from marine resources while preserving the ecosystem’s health. Marine ecosystem services are defined as the benefits people obtain from marine ecosystems. The aim of this study is to determine which interrelations between marine ecosystem services and the marine energy industry can be identified for use in transnational marine spatial planning exemplified in the North Sea region. As the North Sea is one of the busiest seas worldwide, the risk of impairing the ecosystems through anthropogenic pressures is high. Drawing on a literature-based review, 23 marine ecosystem services provided by the North Sea region were defined and linked to seven offshore energy fields comprising oil and natural gas, wind, tides and currents, waves, salinity gradients, algal biomass, and geothermal heat. The interactions were divided into four categories: dependence, impact, bidirectional, or no interaction. Oil and natural gas, as well as algae biomass, are the fields with the most relations with marine ecosystem services while waves and salinity gradients exhibit the least. Some marine ecosystem services (Conditions for Infrastructure, Regulation of Water Flows, and Cognitive Development are needed for all fields; Recreation and Tourism, Aesthetic and Cultural Perceptions and Traditions, Cognitive Development, and Sea Scape are impacted by all fields. The results of this research provide an improved basis for an ecosystem approach in transnational marine spatial planning.

Simultaneous C and N removal from saline salmon effluents in filter reactors comprising anoxic-anaerobic-aerobic processes: effect of recycle ratio.

Science.gov (United States)

Giustinianovich, Elisa A; Aspé, Estrella R; Huiliñir, César E; Roeckel, Marlene D

2014-01-01

Salmon processing generates saline effluents with high protein load. To treat these effluents, three compact tubular filter reactors were installed and an integrated anoxic/anaerobic/aerobic process was developed with recycling flow from the reactor's exit to the inlet stream in order to save organic matter (OM) for denitrification. The reactors were aerated in the upper section with recycle ratios (RR) of 0, 2, and 10, respectively, at 30°C. A tubular reactor behave as a plug flow reactor when RR = 0, and as a mixed flow reactor when recycle increases, thus, different RR values were used to evaluate how it affects the product distribution and the global performance. Diluted salmon process effluent was prepared as substrate. Using loads of 1.0 kg COD m(-3)d(-1) and 0.15 kg total Kjeldahl nitrogen (TKN) m(-3)d(-1) at HRT of 2 d, 100% removal efficiencies for nitrite and nitrate were achieved in the anoxic-denitrifying section without effect of the dissolved oxygen in the recycled flow on denitrification. Removals >98% for total organic carbon (TOC) was achieved in the three reactors. The RR had no effect on the TOC removal; nevertheless a higher efficiency in total nitrogen removal in the reactor with the highest recycle ratio was observed: 94.3% for RR = 10 and 46.6% for RR = 2. Results showed that the proposed layout with an alternative distribution in a compact reactor can efficiently treat high organic carbon and nitrogen concentrations from a saline fish effluent with OM savings in denitrification.

PNNL supercomputer to become largest computing resource on the Grid

CERN Multimedia

2002-01-01

Hewlett Packard announced that the US DOE Pacific Northwest National Laboratory will connect a 9.3-teraflop HP supercomputer to the DOE Science Grid. This will be the largest supercomputer attached to a computer grid anywhere in the world (1 page).

Whale Multi-Disciplinary Studies: A Marine Education Infusion Unit. Northern New England Marine Education Project.

Science.gov (United States)

Maine Univ., Orono. Coll. of Education.

This multidisciplinary unit deals with whales, whaling lore and history, and the interaction of the whale with the complex marine ecosystem. It seeks to teach adaptation of marine organisms. It portrays the concept that man is part of the marine ecosystem and man's activities can deplete and degrade marine ecosystems, endangering the survival of…

Phosphorus dynamics in the Black Sea and Baltic Sea

NARCIS (Netherlands)

Dijkstra, N.|info:eu-repo/dai/nl/372617034

2017-01-01

The dynamics of the key nutrient phosphorus (P) in hypoxic and anoxic marine basins are still incompletely understood. This thesis focuses on the cycling of P in two of such basins: the Baltic Sea and the Black Sea. Water column particulates and sediments from the deep basin of the Black Sea were

Reorganization of a large marine ecosystem due to atmospheric and anthropogenic pressure: a discontinuous regime shift in the Central Baltic Sea

DEFF Research Database (Denmark)

Moellmann, C; Diekmann, Rabea; Muller-Karulis, B

2009-01-01

the Baltic Sea, the largest brackish water body in the world ocean, and its ecosystems are strongly affected by atmospheric and anthropogenic drivers. Here, we present results of an analysis of the state and development of the Central Baltic Sea ecosystem integrating hydroclimatic, nutrient, phyto......Marine ecosystems such as the Baltic Sea are currently under strong atmospheric and anthropogenic pressure. Besides natural and human-induced changes in climate, major anthropogenic drivers such as overfishing and anthropogenic eutrophication are significantly affecting ecosystem structure...

Fate of para-toluenesulfonamide (p-TSA) in groundwater under anoxic conditions: modelling results from a field site in Berlin (Germany).

Science.gov (United States)

Meffe, Raffaella; Kohfahl, Claus; Hamann, Enrico; Greskowiak, Janek; Massmann, Gudrun; Dünnbier, Uwe; Pekdeger, Asaf

2014-01-01

This article reports on a field modelling study to investigate the processes controlling the plume evolution of para-toluenesulfonamide (p-TSA) in anoxic groundwater in Berlin, Germany. The organic contaminant p-TSA originates from the industrial production process of plasticisers, pesticides, antiseptics and drugs and is of general environmental concern for urban water management. Previous laboratory studies revealed that p-TSA is degradable under oxic conditions, whereas it appears to behave conservatively in the absence of oxygen (O2). p-TSA is ubiquitous in the aquatic environment of Berlin and present in high concentrations (up to 38 μg L(-1)) in an anoxic aquifer downgradient of a former sewage farm, where groundwater is partly used for drinking water production. To obtain refined knowledge of p-TSA transport and degradation in an aquifer at field scale, measurements of p-TSA were carried out at 11 locations (at different depths) between 2005 and 2010. Comparison of chloride (Cl(-)) and p-TSA field data showed that p-TSA has been retarded in the same manner as Cl(-). To verify the transport behaviour under field conditions, a two-dimensional transport model was setup, applying the dual-domain mass transfer approach in the model sector corresponding to an area of high aquifer heterogeneity. The distribution of Cl(-) and p-TSA concentrations from the site was reproduced well, confirming that both compounds behave conservatively and are subjected to retardation due to back diffusion from water stagnant zones. Predictive simulations showed that without any remediation measures, the groundwater quality near the drinking water well galleries will be affected by high p-TSA loads for about a hundred years.

Worlds largest particle physics laboratory selects Proxim Wireless Mesh

CERN Multimedia

2007-01-01

"Proxim Wireless has announced that the European Organization for Nuclear Research (CERN), the world's largest particle physics laboratory and the birthplace of the World Wide Web, is using it's ORiNOCO AP-4000 mesh access points to extend the range of the laboratory's Wi-Fi network and to provide continuous monitoring of the lab's calorimeters" (1/2 page)

Discovery of the largest orbweaving spider species: the evolution of gigantism in Nephila.

Science.gov (United States)

Kuntner, Matjaz; Coddington, Jonathan A

2009-10-21

More than 41,000 spider species are known with about 400-500 added each year, but for some well-known groups, such as the giant golden orbweavers, Nephila, the last valid described species dates from the 19(th) century. Nephila are renowned for being the largest web-spinning spiders, making the largest orb webs, and are model organisms for the study of extreme sexual size dimorphism (SSD) and sexual biology. Here, we report on the discovery of a new, giant Nephila species from Africa and Madagascar, and review size evolution and SSD in Nephilidae. We formally describe N. komaci sp. nov., the largest web spinning species known, and place the species in phylogenetic context to reconstruct the evolution of mean size (via squared change parsimony). We then test female and male mean size correlation using phylogenetically independent contrasts, and simulate nephilid body size evolution using Monte Carlo statistics. Nephila females increased in size almost monotonically to establish a mostly African clade of true giants. In contrast, Nephila male size is effectively decoupled and hovers around values roughly one fifth of female size. Although N. komaci females are the largest Nephila yet discovered, the males are also large and thus their SSD is not exceptional.

Discovery of the largest orbweaving spider species: the evolution of gigantism in Nephila.

Directory of Open Access Journals (Sweden)

Matjaz Kuntner

2009-10-01

Full Text Available More than 41,000 spider species are known with about 400-500 added each year, but for some well-known groups, such as the giant golden orbweavers, Nephila, the last valid described species dates from the 19(th century. Nephila are renowned for being the largest web-spinning spiders, making the largest orb webs, and are model organisms for the study of extreme sexual size dimorphism (SSD and sexual biology. Here, we report on the discovery of a new, giant Nephila species from Africa and Madagascar, and review size evolution and SSD in Nephilidae.We formally describe N. komaci sp. nov., the largest web spinning species known, and place the species in phylogenetic context to reconstruct the evolution of mean size (via squared change parsimony. We then test female and male mean size correlation using phylogenetically independent contrasts, and simulate nephilid body size evolution using Monte Carlo statistics.Nephila females increased in size almost monotonically to establish a mostly African clade of true giants. In contrast, Nephila male size is effectively decoupled and hovers around values roughly one fifth of female size. Although N. komaci females are the largest Nephila yet discovered, the males are also large and thus their SSD is not exceptional.

On the statistics of the largest geomagnetic storms per solar cycle

International Nuclear Information System (INIS)

Siscoe, G.L.

1976-01-01

The theory of extreme value statistics is applied to the first, second, and third largest geomagnetic storms in nine solar cycles measured by the average half-daily aa indices compiled by Mayaud. Analytic expressions giving the probability of the extremes per solar cycle as a contour function of storm magnitude are obtained by least squares fitting of the observations to the appropriate theoretical extreme value probability functions. The results are used to obtain the statistical characteristics (mode, median, mean, and standard deviation) for the extreme values. The results are applied to find the expected range of extreme values in a set as a function of the number of solar cycles in the set. We find that the expected range of the largest storm is quite narrow and is larger for the second and third largest storms. The observed range of the extreme half-daily aa index for the nine solar cycles is 354--546 γ. In a set of 100 cycles the range is expanded esentially to 311--680γ, an increase of only 39% in the range. The result supports the argument for a change in solar cycle statistics in the latter part of the Seventeenth Century (the Maunder minimum)

Supermarket Marine Biology.

Science.gov (United States)

Colby, Jennifer A.; And Others

1995-01-01

Describes a survey used to determine the availability of intact marine vertebrates and live invertebrates in supermarkets. Results shows that local supermarkets frequently provide a variety of intact marine organisms suitable for demonstrations, experiments, or dissections. (ZWH)

Marine algae as attractive source to skin care.

Science.gov (United States)

Berthon, Jean-Yves; Nachat-Kappes, Rachida; Bey, Mathieu; Cadoret, Jean-Paul; Renimel, Isabelle; Filaire, Edith

2017-06-01

As the largest organ in the human body, the skin has multiple functions of which one of the most important is the protection against various harmful stressors. The keratinised stratified epidermis and an underlying thick layer of collagen-rich dermal connective tissues are important components of the skin. The environmental stressors such as ultraviolet radiation (UVR) and pollution increase the levels of reactive oxygen species (ROS), contributing to clinical manifestations such as wrinkle formation and skin aging. Skin aging is related to the reduction of collagen production and decrease of several enzymatic activities including matrix metalloproteinases (MMPs), which degrade collagen structure in the dermis; and tissue inhibitor of metalloproteinases (TIMPs), which inhibit the action of MMPs. In addition to alterations of DNA, signal transduction pathways, immunology, UVR, and pollution activate cell surface receptors of keratinocytes and fibroblasts in the skin. This action leads to a breakdown of collagen in the extracellular matrix and a shutdown of new collagen synthesis. Therefore, an efficient antioxidants strategy is of major importance in dermis and epidermis layers. Marine resources have been recognised for their biologically active substances. Among these, marine algae are rich-sources of metabolites, which can be used to fight against oxidative stress and hence skin aging. These metabolites include, among others, mycosporine-like amino acids (MAAs), polysaccharides, sulphated polysaccharides, glucosyl glycerols, pigments, and polyphenols. This paper reviews the role of oxidative processes in skin damage and the action of the compounds from algae on the physiological processes to maintain skin health.

76 FR 77782 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Science.gov (United States)

2011-12-14

..., 1963), but because of ecological or physiological requirements, many marine animals may need to remain... Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Commonwealth of the Northern Mariana Islands, February to March 2012 AGENCY: National Marine Fisheries Service (NMFS), National...

78 FR 17359 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Science.gov (United States)

2013-03-21

..., 1963), but because of ecological or physiological requirements, many marine animals may need to remain... Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Northeast Atlantic Ocean, June to July, 2013 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and...

76 FR 33246 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Science.gov (United States)

2011-06-08

... ecological or physiological requirements, many marine animals may need to remain in areas where they are... Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Central-Western Bering Sea, August 2011 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and...

75 FR 8652 - Incidental Takes of Marine Mammals During Specified Activities; Marine Geophysical Survey in the...

Science.gov (United States)

2010-02-25

... for marine animals before and during airgun operations. NMFS believes that the realistic possibility... Takes of Marine Mammals During Specified Activities; Marine Geophysical Survey in the Commonwealth of the Northern Mariana Islands, April to June 2010 AGENCY: National Marine Fisheries Service (NMFS...

77 FR 19242 - Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Geophysical Survey...

Science.gov (United States)

2012-03-30

...., 1995; Thorpe, 1963), but because of ecological or physiological requirements, many marine animals may... Marine Mammals Incidental to Specified Activities; Low- Energy Marine Geophysical Survey in the Central Pacific Ocean, May Through June, 2012 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

77 FR 25966 - Takes of Marine Mammals Incidental to Specified Activities; Three Marine Geophysical Surveys in...

Science.gov (United States)

2012-05-02

..., 1963), but because of ecological or physiological requirements, many marine animals may need to remain... Marine Mammals Incidental to Specified Activities; Three Marine Geophysical Surveys in the Northeast Pacific Ocean, June Through July 2012 AGENCY: National Marine Fisheries Service, National Oceanic and...

Emerging biopharmaceuticals from marine actinobacteria.

Science.gov (United States)

Hassan, Syed Shams Ul; Anjum, Komal; Abbas, Syed Qamar; Akhter, Najeeb; Shagufta, Bibi Ibtesam; Shah, Sayed Asmat Ali; Tasneem, Umber

2017-01-01

Actinobacteria are quotidian microorganisms in the marine world, playing a crucial ecological role in the recycling of refractory biomaterials and producing novel secondary metabolites with pharmaceutical applications. Actinobacteria have been isolated from the huge area of marine organisms including sponges, tunicates, corals, mollusks, crabs, mangroves and seaweeds. Natural products investigation of the marine actinobacteria revealed that they can synthesize numerous natural products including alkaloids, polyketides, peptides, isoprenoids, phenazines, sterols, and others. These natural products have a potential to provide future drugs against crucial diseases like cancer, HIV, microbial and protozoal infections and severe inflammations. Therefore, marine actinobacteria portray as a pivotal resource for marine drugs. It is an upcoming field of research to probe a novel and pharmaceutically important secondary metabolites from marine actinobacteria. In this review, we attempt to summarize the present knowledge on the diversity, chemistry and mechanism of action of marine actinobacteria-derived secondary metabolites from 2007 to 2016. Copyright © 2016 Elsevier B.V. All rights reserved.

Geochemical imprint of depositional conditions on organic matter in laminated-Bioturbated interbeds from fine-grained marine sequences

Science.gov (United States)

Pratt, L.M.; Claypool, G.E.; King, J.D.

1986-01-01

Laminated organic-rich shales are interbedded at a scale of centimeters to a few meters with bioturbated organic-poor mudstones or limestones in some fine-grained marine sequences. We have analyzed the organic matter in pairs of laminated/bioturbated interbeds from Cretaceous and Devonian rocks deposited in epicontinental and oceanic settings for the purpose of studying the influence of depositional and early diagenetic environment on the organic geochemical properties of marine shales. Results of these analyses indicate that for rocks that are still in a diagenetic stage of thermal alteration, the relative abundance of biomarker compounds and specific biomarker indices can be useful indicators of depositional and early diagenetic conditions. Pristane/phytane ratios are generally highest for laminated rocks from epicontinental basins and appear to reflect the input of isoprenoid precursors more than oxygenated versus anoxic depositional conditions. The thermally immature laminated rocks are characterized by relatively high contents of 17??(H), 21??(H)-hopanes, hopenes, sterenes and diasterenes, and by strong predominance of the 22R over 22S homohopane isomers. Thermally immature bioturbated samples are characterized by absence of the ??,??-hopanes, by low contents of both saturated and unsaturated polycyclic hydrocarbons, and by slight or no predominance of the 22R over 22S homohopane isomers. There are less obvious compositional differences between the saturated hydrocarbons in the laminated and bioturbated units from the thermally mature sequences. For both the thermally mature and immature laminated samples, the degree of isomerization at the 22C position for hopanes and at the 20C position for steranes is generally consistent with the degree of thermal maturity interpreted from other properties of the organic matter. The bioturbated samples, however, exhibit inconsistent and anomalously high degrees of isomerization for the homohopanes, resulting either from

Mechanisms and energetics of surface reactions at the copper-water interface. A critical literature review with implications for the debate on corrosion of copper in anoxic water

Energy Technology Data Exchange (ETDEWEB)

Johansson, Adam Johannes; Brinck, Tore [Applied Physical Chemistry, KTH Royal Inst. of Technology, Stockholm (Sweden)

2012-06-15

In order to make a critical analysis of the discussion of corrosion of copper in pure anoxic water it is necessary to understand the chemical reactivity at the copper-water interface. Even though the most fundamental issue, i.e. the nature and existence of a hypothetical product that is thermodynamically stable, is still under debate, it is clear that if anoxic corrosion really exists, it must be initiated through oxidative surface reactions at the copper-water interface. This report presents a survey of the peer reviewed literature on the reactivity of copper surfaces in water. Reactions discussed involve molecular adsorption of water, dissociation of the OH-bonds in adsorbed water molecules and hydroxyl groups, the disproportionation/synproportionation equilibrium between hydroxyl groups/hydroxide ions, water molecules and atomic oxygen, the surface diffusion of adsorbed species, and the formation of hydrogen gas (molecular hydrogen). Experimental, as well as theoretical (quantum chemical) studies are reviewed. It is concluded that a limited amount of hydrogen gas (H{sub 2}) should be formed as the result of dissociative water adsorption at certain copper surfaces. Quantitative estimates of the amounts of H2 that could form at the copper-water interface are made. Assuming that the water-cleavage/hydrogen-formation reaction proceeds on an ideal [110] or [100] surface until a hydroxyl monolayer (ML) is reached, the amount of H{sub 2} formed is {approx} 2.4 ng cm{sup -2} copper surface. Based on the literature cited, this is most likely possible, thermodynamically as well as kinetically. Although not proven, it is not unlikely that the reaction can proceed until an oxide ML is formed, which would give 4.8 ng cm{sup -2}. If the formation of an oxide ML is thermodynamically feasible the surface will probably react further, since Cu{sub 2}O(s) is known to activate and cleave the water molecule when it adsorbs at the Cu{sub 2}O(s) surface. Assuming the formation of a

Marine Mineral Exploration

DEFF Research Database (Denmark)

in EEZ areas are fairly unknown; many areas need detailed mapping and mineral exploration, and the majority of coastal or island states with large EEZ areas have little experience in exploration for marine hard minerals. This book describes the systematic steps in marine mineral exploration....... Such exploration requires knowledge of mineral deposits and models of their formation, of geophysical and geochemical exploration methods, and of data evaluation and interpretation methods. These topics are described in detail by an international group of authors. A short description is also given of marine...

76 FR 68720 - Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Geophysical Survey...

Science.gov (United States)

2011-11-07

... Marine Mammals Incidental to Specified Activities; Low- Energy Marine Geophysical Survey in the Western... conducting a low-energy marine geophysical (i.e., seismic) survey in the western tropical Pacific Ocean... Science Foundation (NSF), and ``Environmental Assessment of a Low-Energy Marine Geophysical Survey by the...

76 FR 18167 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Science.gov (United States)

2011-04-01

..., many marine animals may need to remain in areas where they are exposed to chronic stimuli (Richardson... Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Central Gulf of Alaska, June, 2011 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric...