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  • 2020-2023  (1)
  • 2010-2014  (8)
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  • 1
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    Specific microbial biomarker signatures from Congo fan sediments of ODP site 175-1075, Congo soils, wetland and estuary sediments (2014)
    PANGAEA
    In:  Supplement to: Talbot, Helen M; Handley, Luke; Spencer-Jones, Charlotte L; Dinga, Bienvenu Jean; Schefuß, Enno; Mann, Paul James; Poulsen, John R; Spencer, Robert GM; Wabakanghanzi, Jose N; Wagner, Thomas (2014): Variability in aerobic methane oxidation over the past 1.2Myrs recorded in microbial biomarker signatures from Congo fan sediments. Geochimica et Cosmochimica Acta, 133, 387-401, https://doi.org/10.1016/j.gca.2014.02.035
    Details
    Publication Date: 2024-02-02
    Description: Methane (CH4) is a strong greenhouse gas known to have perturbed global climate in the past, especially when released in large quantities over short time periods from continental or marine sources. It is therefore crucial to understand and, if possible, quantify the individual and combined response of these variable methane sources to natural climate variability. However, past changes in the stability of greenhouse gas reservoirs remain uncertain and poorly constrained by geological evidence. Here, we present a record from the Congo fan of a highly specific bacteriohopanepolyol (BHP) biomarker for aerobic methane oxidation (AMO), 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol), that identifies discrete periods of increased AMO as far back as 1.2 Ma. Fluctuations in the concentration of aminopentol, and other 35-aminoBHPs, follow a pattern that correlates with late Quaternary glacial-interglacial climate cycles, with highest concentrations during warm periods. We discuss possible sources of aminopentol, and the methane consumed by the precursor methanotrophs, within the context of the Congo River setting, including supply of methane oxidation markers from terrestrial watersheds and/or marine sources (gas hydrate and/or deep subsurface gas reservoir). Compound-specific carbon isotope values of -30 per mil to -40 per mil for BHPs in ODP 1075 and strong similarities between the BHP signature of the core and surface sediments from the Congo estuary and floodplain wetlands from the interior of the Congo River Basin, support a methanotrophic and likely terrigenous origin of the 35-aminoBHPs found in the fan sediments. This new evidence supports a causal connection between marine sediment BHP records of tropical deep sea fans and wetland settings in the feeding river catchments, and thus tropical continental hydrology. Further research is needed to better constrain the different sources and pathways of methane emission. However, this study identifies the large potential of aminoBHPs, in particular aminopentol, to trace and, once better calibrated and understood, quantify past methane sources and fluxes from terrestrial and potentially also marine sources.
    Keywords: Center for Marine Environmental Sciences; MARUM; Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 2
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    (Table S1) Total organic carbon and concentration of C-35 aminoBHPs in ODP Site 175-1075 Congo Fan sediments (2014)
    PANGAEA
    Details
    Publication Date: 2024-02-02
    Keywords: 175-1075; Aminopentol, per unit mass total organic carbon; Aminopentol isomer, per unit mass total organic carbon; Aminotetrol, per unit mass total organic carbon; Aminotriol, per unit mass total organic carbon; Benguela Current, South Atlantic Ocean; Carbon, organic, total; COMPCORE; Composite Core; Depth, composite; DEPTH, sediment/rock; Joides Resolution; Leg175; Ocean Drilling Program; ODP
    Type: Dataset
    Format: text/tab-separated-values, 630 data points
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    DATA PANGAEA
  • 3
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    (Table 1) Selected samples from ODP Site 175-1075 subjected to compound specific stable carbon isotope analysis (2014)
    PANGAEA
    Details
    Publication Date: 2024-02-02
    Keywords: 175-1075; AGE; Benguela Current, South Atlantic Ocean; C30-Hopanol; C30-Hopanol, δ13C; C31-Hopanol; C31-Hopanol, δ13C; C32-Hopanol; C32-Hopanol, δ13C; COMPCORE; Composite Core; Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS); Joides Resolution; Leg175; Ocean Drilling Program; ODP; Sample code/label; Standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 67 data points
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    DATA PANGAEA
  • 4
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    (Table S2) Total organic carbon and concentration of C-35 aminoBHPs in Congo soils, wetland and Estuary sediments (2014)
    PANGAEA
    Details
    Publication Date: 2024-02-02
    Keywords: Aminopentol, per unit mass total organic carbon; Aminopentol isomer, per unit mass total organic carbon; Aminotetrol, per unit mass total organic carbon; Aminotriol, per unit mass total organic carbon; Anker24; Area/locality; Carbon, organic, total; Center for Marine Environmental Sciences; DEPTH, sediment/rock; Elevation of event; Event label; Grab; GRAB; Latitude of event; Longitude of event; MARUM; Sample comment
    Type: Dataset
    Format: text/tab-separated-values, 174 data points
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    DATA PANGAEA
  • 5
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    Structural evolution of the Dayman dome metamorphic core complex, eastern Papua New Guinea (2011)
    Geological Society of America (GSA)
    Details
    Publication Date: 2011-11-01
    Description: A shallow-dipping ductile mylonitic shear zone and concordant brittle detachment fault (Mai'iu fault) together make up the dominant geological structure that controls the orientation of dip slopes on the flanks of Mount Dayman, eastern Papuan Peninsula, Papua New Guinea. The dip slopes dip in all directions from the peak of Mount Dayman and form a domed landform that is much less dissected by streams compared to the adjacent Mount Suckling domed landform. The orientation of megacorrugations on the domed surface of Mount Dayman (footwall) is consistent with NNE-directed transport of the hanging-wall block, which is composed of low-grade undifferentiated volcanic and sedimentary rocks and minor ultramafic rocks. Though previously documented as a thrust surface, the geometry and style of structures and map relations presented in this study indicate an extensional origin for the domed mylonitic foliation (S1) and mineral elongation lineation (L1). The field relationships are consistent with the domed landform comprising the core of a metamorphic core complex. Observations of dominantly NNE-trending regional lineaments in aerial photography and Shuttle Radar Topography Mission (SRTM) data correlate with detailed field analysis of mineral elongation lineations (L1) in the main metamorphic core complex-bounding shear zone. Field relationships show a crosscutting sequence of structures that includes: (1) ductile S2 folia with ESE-plunging blue sodic-calcic amphibole mineral elongation lineations; (2) narrow, steeply dipping ductile D2 shear zones; and (3) semibrittle to brittle fault zones. S-C' fabrics, asymmetric strain shadows around porphyroclasts, and fault drag indicate a top-down-to-the-NNE sense of shear for most structures. Kinematic vorticity analysis of the highest-grade ductile deformation indicates a kinematic vorticity number (Wk) between 0.34 and 0.56, suggesting general shear for the early stage of deformation (D1). The NNE-directed lineaments and L1 mineral elongation lineations are consistent with the Australia-Woodlark Eulerian pole for periods between the early Pliocene (3.6 Ma) and Pleistocene (0.52 Ma). This observation is consistent with ca. 3.3 Ma granite and monzonite intrusions that cut the mylonitic fabrics and limit the age of the mylonitic fabrics to older than 3.3 Ma on Mount Suckling. A SE-dipping sedimentary sequence (Gwoira Conglomerate) characterizes part of the hanging wall of the metamorphic core complex. Petrography of the clasts within the sedimentary rocks indicates that metabasite rocks were the dominant source. The unit is in fault contact with the metabasite footwall across prehnite-bearing D3 brittle fault zones.
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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    PAPER CURRENT
  • 6
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    A pilot randomised controlled trial of personalised care for depressed patients with symptomatic coronary heart disease in south London general practices: The UPBEAT-UK RCT protocol and recruitment. (2012)
    BioMed Central
    Details
    Publication Date: 2012-06-11
    Description: Background: Community studies reveal people with coronary heart disease (CHD) are twice as likely to be depressed as the general population and that this co-morbidity negatively affects the course and outcome of both conditions. There is evidence for the efficacy of collaborative care and case management for depression treatment, and whilst NICE guidelines recommend these approaches only where depression has not responded to psychological, pharmacological, or combined treatments, these care approaches may be particularly relevant to the needs of people with CHD and depression in the earlier stages of stepped care in primary care settings. Methods: This pilot randomised controlled trial will evaluate whether a simple intervention involving a personalised care plan, elements of case management and regular telephone review is a feasible and acceptable intervention that leads to better mental and physical health outcomes for these patients. The comparator group will be usual general practitioner (GP) care.81 participants have been recruited from CHD registers of 15 South London general practices. Eligible participants have probable major depression identified by a score of [greater than or equal to]8 on the Hospital Anxiety and Depression Scale depression subscale (HADS-D) together with symptomatic CHD identified using the Modified Rose Angina Questionnaire.Consenting participants are randomly allocated to usual care or the personalised care intervention which involves a comprehensive assessment of each participant's physical and mental health needs which are documented in a care plan, followed by regular telephone reviews by the case manager over a 6-month period. At each review, the intervention participant's mood, function and identified problems are reviewed and the case manager uses evidence based behaviour change techniques to facilitate achievement of goals specified by the patient with the aim of increasing the patient's self efficacy to solve their problems.Depressive symptoms measured by HADS score will be collected at baseline and 1, 6- and 12 months post randomisation. Other outcomes include CHD symptoms, quality of life, wellbeing and health service utilisation.DiscussionThis practical and patient-focused intervention is potentially an effective and accessible approach to the health and social care needs of people with depression and CHD in primary care.Trial registrationISRCTN21615909
    Electronic ISSN: 1471-244X
    Topics: Medicine
    Published by BioMed Central
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  • 7
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    Particulate organic matter in the Lena River and its Delta: From the permafrost catchment to the Arctic Ocean (2022)
    In:  EPIC3Particulate organic matter in the Lena River and its Delta: From the permafrost catchment to the Arctic Ocean, Biogeosciences Discussions
    Details
    Publication Date: 2022-09-29
    Description: Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers, and ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers, despite the likely impact of highly dynamic estuarine and deltaic environments on transformation, storage, and age of OM delivered to coastal waters. Here, we studied OM dynamics within the Lena River main stem and Lena Delta along an approximately ∼1600 km long transect from Yakutsk, downstream to the delta disembogue into the Laptev Sea. We measured particulate organic carbon (POC), total suspended matter (TSM), and carbon isotopes (δ13C and ∆14C) in POC to compare riverine and deltaic OM composition and changes in OM source and fate during transport offshore. We found that TSM and POC concentrations decreased by 55 and 70 %, respectively, during transit from the main stem to the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in 13C relative to fluvial POC, indicating a significant phytoplankton contribution to deltaic POC (∼68 ±6 %). Dual-carbon (∆14C and δ13C) isotope mixing model analyses suggested an additional input of permafrost-derived OM into deltaic waters (∼18 ±4 % of deltaic POC originates from Pleistocene deposits vs ∼ 5 ±4 % in the river main stem). Despite the lower concentration of POC in the delta than in the main stem (0.41 ±0.10 vs. 0.79 ±0.30 mg L-1, respectively ), the amount of POC derived from Pleistocene deposits in deltaic waters was almost twice as large as POC of Yedoma origin in the main stem (0.07 ±0.02 and 0.04 ±0.02 mg L-1, respectively). We assert that estuarine and deltaic processes require consideration in order to correctly understand OM dynamics throughout Arctic nearshore coastal zones and how these processes may evolve under future climate-driven change.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , notRev
    Format: application/pdf
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  • 8
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    Inorganic carbon speciation and fluxes in the Congo River (2013)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 511–516, doi:10.1002/grl.50160.
    Description: Seasonal variations in inorganic carbon chemistry and associated fluxes from the Congo River were investigated at Brazzaville-Kinshasa. Small seasonal variation in dissolved inorganic carbon (DIC) was found in contrast with discharge-correlated changes in pH, total alkalinity (TA), carbonate species, and dissolved organic carbon (DOC). DIC was almost always greater than TA due to the importance of CO2*, the sum of dissolved CO2 and carbonic acid, as a result of low pH. Organic acids in DOC contributed 11–61% of TA and had a strong titration effect on water pH and carbonate speciation. The CO2* and bicarbonate fluxes accounted for ~57% and 43% of the DIC flux, respectively. Congo River surface water released CO2 at a rate of ~109 mol m−2 yr−1. The basin-wide DIC yield was ~8.84 × 104 mol km−2 yr−1. The discharge normalized DIC flux to the ocean amounted to 3.11 × 1011 mol yr−1. The DOC titration effect on the inorganic carbon system may also be important on a global scale for regulating carbon fluxes in rivers.
    Description: This project was supported by a grant from the National Science Foundation for the Global Rivers Project (NSF 0851101).
    Description: 2013-08-14
    Keywords: Inorganic carbon ; Carbon dioxide ; Carbon fluxes ; pH ; Alkalinity ; Congo River
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 9
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    The biogeochemistry of carbon across a gradient of streams and rivers within the Congo Basin (2014)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2014. 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: Biogeosciences 119 (2014): 687–702, doi:10.1002/2013JG002442.
    Description: Dissolved organic carbon (DOC) and inorganic carbon (DIC, pCO2), lignin biomarkers, and theoptical properties of dissolved organic matter (DOM) were measured in a gradient of streams and rivers within the Congo Basin, with the aim of examining how vegetation cover and hydrology influences the composition and concentration of fluvial carbon (C). Three sampling campaigns (February 2010, November 2010, and August 2011) spanning 56 sites are compared by subbasin watershed land cover type (savannah, tropical forest, and swamp) and hydrologic regime (high, intermediate, and low). Land cover properties predominately controlled the amount and quality of DOC, chromophoric DOM (CDOM) and lignin phenol concentrations (∑8) exported in streams and rivers throughout the Congo Basin. Higher DIC concentrations and changing DOM composition (lower molecular weight, less aromatic C) during periods of low hydrologic flow indicated shifting rapid overland supply pathways in wet conditions to deeper groundwater inputs during drier periods. Lower DOC concentrations in forest and swamp subbasins were apparent with increasing catchment area, indicating enhanced DOC loss with extended water residence time. Surface water pCO2 in savannah and tropical forest catchments ranged between 2,600 and 11,922 µatm, with swamp regions exhibiting extremely high pCO2 (10,598–15,802 µatm), highlighting their potential as significant pathways for water-air efflux. Our data suggest that the quantity and quality of DOM exported to streams and rivers are largely driven by terrestrial ecosystem structure and that anthropogenic land use or climate change may impact fluvial C composition and reactivity, with ramifications for regional C budgets and future climate scenarios.
    Description: This work was supported by the National Science Foundation as part of the ETBC Collaborative Research: Controls on the Flux, Age, and Composition of Terrestrial Organic Carbon Exported by Rivers to the Ocean (0851101 and 0851015).
    Description: 2014-10-30
    Keywords: Dissolved organic matter ; Lignin ; CDOM ; pCO2 ; Aquatic ; Hydrology
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: text/richtext
    Format: application/vnd.ms-excel
    Format: application/pdf
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