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  • 11
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Springer, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 90 (2008): 15-27, doi:10.1007/s10533-008-9227-2.
    Beschreibung: Nitrogen from atmospheric deposition serves as the dominant source of new nitrogen to forested ecosystems in the northeastern U.S.. By combining isotopic data obtained using the denitrifier method, with chemistry and hydrology measurements we determined the relative importance of sources and control mechanisms on nitrate (NO3-) export from five forested watersheds in the Connecticut River watershed. Microbially produced NO3- was the dominant source (82-100%) of NO3- to the sampled streams as indicated by the δ15N and δ18O of NO3-. Seasonal variations in the δ18O-NO3- in streamwater are controlled by shifting hydrology and temperature affects on biotic processing, resulting in a relative increase in unprocessed NO3- export during winter months. Mass balance estimates find that the unprocessed atmospherically derived NO3- stream flux represents less than 3% of the atmospherically delivered wet NO3- flux to the region. This suggests that despite chronically elevated nitrogen deposition these forests are not nitrogen saturated and are retaining, removing, and reprocessing the vast majority of NO3- delivered to them throughout the year. These results confirm previous work within Northeastern U.S. forests and extend observations to watersheds not dominated by a snow-melt driven hydrology. In contrast to previous work, unprocessed atmospherically derived NO3- export is associated with the period of high recharge and low biotic activity as opposed to spring snowmelt and other large runoff events.
    Beschreibung: This work was funded by an EPA STAR Fellowship (FP-91637501-1) and a grant from QLF/The Sound Conservancy to RTB.
    Schlagwort(e): Atmospheric deposition ; Forests ; Nitrogen ; Stable isotopes
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
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  • 12
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1796–1808, doi:10.1038/ismej.2011.58.
    Beschreibung: Archaeal genes for ammonia oxidation are widespread in the marine environment, but direct physiological evidence for ammonia oxidation by marine archaea is limited. We report the enrichment and characterization of three strains of pelagic ammonia-oxidizing archaea (AOA) from the north Pacific Ocean that have been maintained in laboratory culture for over three years. Phylogenetic analyses indicate the three strains belong to a previously identified clade of water column-associated AOA and possess 16S rRNA genes and ammonia monooxygenase subunit a (amoA) genes highly similar (98-99% identity) to those recovered in DNA and cDNA clone libraries from the open ocean. The strains grow in natural seawater-based liquid medium while stoichiometrically converting ammonium (NH4 +) to nitrite (NO2 -). Ammonia oxidation by the enrichments is only partially inhibited by allylthiourea at concentrations known to inhibit cultivated ammonia-oxidizing bacteria. The three strains were used to determine the nitrogen stable isotope effect (15εNH3) during archaeal ammonia oxidation, an important parameter for interpreting stable isotope ratios in the environment. Archaeal 15εNH3 ranged from 13- 41‰, within the range of that previously reported for ammonia-oxidizing bacteria. Despite low amino acid identity between the archaeal and bacterial Amo proteins, their functional diversity as captured by 15εNH3 is similar.
    Beschreibung: This work was supported by a Woods Hole Oceanographic Institution (WHOI) Postdoctoral Scholar fellowship to AES and the WHOI Ocean Life Institute.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
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  • 13
    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chemical Geology 493 (2018): 210-223, doi:10.1016/j.chemgeo.2018.05.040.
    Beschreibung: The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 25 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017. This article is part of a special issue entitled: Conway GEOTRACES - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.
    Beschreibung: We gratefully acknowledge financial support by the Scientific Committee on Oceanic Research (SCOR) through grants from the U.S. National Science Foundation, including grants OCE-0608600, OCE-0938349, OCE-1243377, and OCE-1546580. Financial support was also provided by the UK Natural Environment Research Council (NERC), the Ministry of Earth Science of India, the Centre National de Recherche Scientifique, l'Université Paul Sabatier de Toulouse, the Observatoire Midi-Pyrénées Toulouse, the Universitat Autònoma de Barcelona, the Kiel Excellence Cluster The Future Ocean, the Swedish Museum of Natural History, The University of Tokyo, The University of British Columbia, The Royal Netherlands Institute for Sea Research, the GEOMAR-Helmholtz Centre for Ocean Research Kiel, and the Alfred Wegener Institute.
    Schlagwort(e): GEOTRACES ; Trace elements ; Isotopes ; Electronic atlas ; IDP2017
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 14
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 57 (2012): 989-1010, doi:10.4319/lo.2012.57.4.0989.
    Beschreibung: We present full-depth zonal sections of total dissolved cobalt, iron, manganese, and labile cobalt from the South Atlantic Ocean. A basin-scale plume from the African coast appeared to be a major source of dissolved metals to this region, with high cobalt concentrations in the oxygen minimum zone of the Angola Dome and extending 2500 km into the subtropical gyre. Metal concentrations were elevated along the coastal shelf, likely due to reductive dissolution and resuspension of particulate matter. Linear relationships between cobalt, N2O, and O2, as well as low surface aluminum supported a coastal rather than atmospheric cobalt source. Lateral advection coupled with upwelling, biological uptake, and remineralization delivered these metals to the basin, as evident in two zonal transects with distinct physical processes that exhibited different metal distributions. Scavenging rates within the coastal plume differed for the three metals; iron was removed fastest, manganese removal was 2.5 times slower, and cobalt scavenging could not be discerned from water mass mixing. Because scavenging, biological utilization, and export constantly deplete the oceanic inventories of these three hybrid-type metals, point sources of the scale observed here likely serve as vital drivers of their oceanic cycles. Manganese concentrations were elevated in surface waters across the basin, likely due to coupled redox processes acting to concentrate the dissolved species there. These observations of basin-scale hybrid metal plumes combined with the recent projections of expanding oxygen minimum zones suggest a potential mechanism for effects on ocean primary production and nitrogen fixation via increases in trace metal source inputs.
    Beschreibung: This research was supported US National Science Foundation Chemical Oceanography (Division of Ocean Sciences OCE-0452883, OCE-0752291, OCE-0928414, OCE-1031271), the Center for Microbial Research and Education, the Gordon and Betty Moore Foundation, the WHOI Coastal Ocean Institute, and the WHOI Ocean Life Institute.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 15
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 76 (2010): 7938-7948, doi:10.1128/AEM.02056-09.
    Beschreibung: Nitrification, the microbially-catalyzed oxidation of ammonia to nitrate, is a key process in the nitrogen cycle. Archaea have been implicated in the first part of the nitrification pathway (oxidation of ammonia to nitrite), but the ecology and physiology of these organisms remain largely unknown. This work describes two different populations of sediment-associated ammonia-oxidizing archaea (AOA) in a coastal groundwater system on Cape Cod, Massachusetts. Sequence analysis of the ammonia monooxygenase subunit A gene (amoA) shows that one population of putative AOA inhabits the upper meter of the sediment where they may experience frequent ventilation with tidally-driven overtopping and infiltration of bay water supplying dissolved oxygen, ammonium and perhaps organic carbon. A genetically distinct population occurs deeper in the sediment, in a mixing zone between a nitrate- and oxygen-rich freshwater zone and a reduced, ammonium-bearing salt water wedge. Both of these AOA populations are coincident with increases in the abundance of Group I crenarchaeota 16S rRNA gene copies.
    Beschreibung: Funding was provided by WHOI’s Coastal Ocean Institute to DRR and KLC, as well as funding from NSF/OCE project #05-24994 to KLC.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
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  • 16
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): G03002, doi:10.1029/2012JG001949.
    Beschreibung: Until recently, the process of denitrification (conversion of nitrate or nitrite to gaseous products) was thought to be performed exclusively by prokaryotes and fungi. The finding that foraminifera perform complete denitrification could impact our understanding of nitrate removal in sediments as well as our understanding of eukaryotic respiration, especially if it is widespread. However, details of this process and the subcellular location of these reactions in foraminifera remain uncertain. For example, prokaryotic endobionts, rather than the foraminifer proper, could perform denitrification, as has been shown recently in an allogromiid foraminifer. Here, intracellular nitrate concentrations and isotope ratios (δ15NNO3 and δ18ONO3) were measured to assess the nitrate dynamics in four benthic foraminiferal species (Bolivina argentea, Buliminella tenuata, Fursenkoina cornuta, Nonionella stella) with differing cellular architecture and associations with microbial endobionts, recovered from Santa Barbara Basin, California. Cellular nitrate concentrations were high (12–217 mM) in each species, and intracellular nitrate often had elevated δ15NNO3 and δ18ONO3 values. Experiments including suboxic and anoxic incubations of B. argentea revealed a decrease in intracellular nitrate concentration and an increase in δ15NNO3 and δ18ONO3 over time, indicating nitrate respiration and/or denitrification within the foraminifera. Results illustrate that nitrate reduction occurs in a range of foraminiferal species, including some possessing endobionts (including a chloroplast-sequestering species) and others lacking endobionts, implying that microbial associates may not solely be responsible for this process in foraminifera. Furthermore, we show that benthic foraminifera may represent important reservoirs of nitrate storage in sediments, as well as mediators of its removal.
    Beschreibung: This research was supported by NSF grant EF-0702491 to JMB, KLC, and VPE.
    Beschreibung: 2013-01-03
    Schlagwort(e): SSU rRNA ; Santa Barbara Basin ; Denitrification ; NirK ; NirS ; Symbiosis
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 17
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    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Publikationsdatum: 2022-05-25
    Beschreibung: 15N2 incubation-based N2 fixation rates, nitrate plus nitrite concentration and d15N, sediment trap PN mass flux and isotopic composition from the Eastern Tropical South Pacific, 2010 and 2011
    Beschreibung: An extensive region of the Eastern Tropical South Pacific (ETSP) Ocean has surface waters that are nitrate-poor yet phosphate-rich. It has been proposed that this distribution of surface nutrients provides a geochemical niche favorable for N2 fixation, the primary source of nitrogen to the ocean. Here, we present results from two cruises to the ETSP where rates of N2 fixation and its contribution to export production were determined with a suite of geochemical and biological measurements. N2 fixation was only detectable using nitrogen isotopic mass balances at two of six stations, and rates ranged from 0 to 23 µmol N m-2 d-1 based on sediment trap fluxes. Whereas the fractional importance of N2 fixation did not change, the N2-fixation rates at these two stations were several-fold higher when scaled to other productivity metrics. Regardless of the choice of productivity metric these N2-fixation rates are low compared with other oligotrophic locations, and the nitrogen isotope budgets indicate that N2 fixation supports no more than 20% of export production regionally. Although euphotic zone-integrated short-term N2-fixation rates were higher, up to 100 µmol N m-2 d-1, and detected N2 fixation at all six stations, studies of nitrogenase gene abundance and expression from the same cruises align with the geochemical data and together indicate that N2 fixation is a minor source of new nitrogen to surface waters of the ETSP. This finding is consistent with the hypothesis that, despite a relative abundance of phosphate, iron may limit N2 fixation in the ETSP.
    Beschreibung: NSF-OCE-0850801, NSF-OCE-0850905, NSF-OCE-0961098
    Beschreibung: 2016-04-15
    Schlagwort(e): Sediment trap ; Nitrogen fixation ; Eastern Tropical South Pacific ; Delta 15N ; PN, particulate nitrogen
    Repository-Name: Woods Hole Open Access Server
    Materialart: Dataset
    Format: application/pdf
    Format: text/plain
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  • 18
    Publikationsdatum: 2017-01-04
    Beschreibung: Citation only. Published in Science 316: 567-570, doi: 10.1126/science.1137959
    Beschreibung: Funding was obtained primarily through the NSF, Ocean Sciences Programs in Chemical and Biological Oceanography, with additional support from the U.S. Department of Energy, Office of Science, Biological and Environmental Research Program, and other national programs, including the Australian Cooperative Research Centre program and Australian Antarctic Division.
    Schlagwort(e): Carbon flux ; Carbon sequestration ; Biological pump
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 19
    Publikationsdatum: 2022-10-31
    Beschreibung: Dataset: ETSP qPCR
    Beschreibung: Water column amoA and Nitrospina-like 16S rRNA gene abundances from qPCR in the Eastern Tropical South Pacific using seawater collected on R/V Atlantis (AT15-61) cruise in Jan-Feb 2010 and R/V Melville (MV1104) cruise in Mar-Apr 2011. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/826781
    Beschreibung: NSF Division of Ocean Sciences (NSF OCE) OCE-0961098
    Schlagwort(e): qPCR ; Ammonia oxidation ; Nitrite oxidizing bacteria ; Ammonia monooxygenase ; Nitrospina
    Repository-Name: Woods Hole Open Access Server
    Materialart: Dataset
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  • 20
    Publikationsdatum: 2022-10-31
    Beschreibung: Dataset: ETSP NO2 NH4
    Beschreibung: Dissolved nitrite ([NO2-]) and ammonium ([NH4+]) concentration data were collected on two cruises in the Eastern Tropical South Pacific. Data from R/V Atlantis (AT15-61) cruise collected in Jan-Feb 2010 and data from R/V Melville (MV1104) cruise collected in Mar-Apr 2011 as part of the Microbial Nitrification project. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/820165
    Beschreibung: NSF Division of Ocean Sciences (NSF OCE) OCE-0961098
    Schlagwort(e): Nitrite ; Ammonium ; AT15-61 ; MV1104 ; Concentration data ; ETSP ; OMZ
    Repository-Name: Woods Hole Open Access Server
    Materialart: Dataset
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