64 research outputs found

    SUB-OCEAN: subsea dissolved methane measurements using an embedded laser spectrometer technology

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science and Technology, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.est.7b06171.We present a novel instrument, the Sub-Ocean probe, allowing in situ and continuous measurements of dissolved methane in seawater. It relies on an optical feedback cavity enhanced absorption technique designed for trace gas measurements and coupled to a patent-pending sample extraction method. The considerable advantage of the instrument compared with existing ones lies in its fast response time of the order of 30 s, that makes this probe ideal for fast and continuous 3D-mapping of dissolved methane in water. It could work up to 40 MPa of external pressure and it provides a large dynamic range, from subnmol of CH4 per liter of seawater to mmol L-1. In this work, we present laboratory calibration of the instrument, intercomparison with standard method and field results on methane detection. The good agreement with the headspace equilibration technique followed by gas-chromatography analysis supports the utility and accuracy of the instrument. A continuous 620-m depth vertical profile in the Mediterranean Sea was obtained within only 10 min and it indicates background dissolved CH4 values between 1 and 2 nmol L-1 below the pycnocline, similar to previous observations conducted in different ocean settings. It also reveals a methane maximum at around 6 m of depth that may reflect local production from bacterial transformation of dissolved organic matter

    DBCP Drifting Buoys GDAC data management report 2021

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    This report covers the activity of Drifting Data Buoys Global Data Assembly Centre (DDB GDAC) published for Data Buoy Cooperation Panel (DBCP) Thirty Seventh Session

    Cardinal Buoys: An Opportunity for the Study of Air-Sea CO 2 Fluxes in Coastal Ecosystems

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    International audienceFrom 2015 to 2019 we installed high-frequency (HF) sea surface temperature (SST), salinity, fluorescence, dissolved oxygen (DO) and partial pressure of CO 2 (pCO 2) sensors on a cardinal buoy of opportunity (ASTAN) at a coastal site in the southern Western English Channel (sWEC) highly influenced by tidal cycles. The sensors were calibrated against bimonthly discrete measurements performed at two long-term time series stations near the buoy, thus providing a robust multi-annual HF dataset. The tidal transport of a previously unidentified coastal water mass and an offshore water mass strongly impacted the daily and seasonal variability of pCO 2 and pH. The maximum tidal variability associated to spring tides (>7 m) during phytoplankton blooms represented up to 40% of the pCO 2 annual signal at ASTAN. At the same time, the daily variability of 0.12 pH units associated to this tidal transport was 6 times larger than the annual acidification trend observed in the area. A frequency/time analysis of the HF signal revealed the presence of a day/night cycle in the tidal signal. The diel biological cycle accounted for 9% of the annual pCO 2 amplitude during spring phytoplankton blooms. The duration and intensity of the biologically productive periods, characterized by large inter-annual variability, were the main drivers of pCO 2 dynamics. HF monitoring enabled us to accurately constrain, for the first-time, annual estimates of air-sea CO 2 exchanges in the nearshore tidally-influenced waters of the sWEC, which were a weak source to the atmosphere at 0.51 mol CO 2 m −2 yr −1. This estimate, combined with previous studies, provided a full latitudinal representation of the WEC (from 48 ‱ 75 N to 50 ‱ 25 N) over multiple years for air-sea CO 2 fluxes in contrasted coastal ecosystems. The latitudinal comparison showed a clear gradient from a weak source of CO 2 in the tidal mixing region toward sinks of CO 2 in the stratified region with a seasonal thermal front separating these hydrographical provinces. In view of the fact that several continental shelf regions have been reported to have switched from sources to sinks of CO 2 in the last century, weak CO 2 sources in such tidal mixing areas could potentially become sinks of atmospheric CO 2 in coming decades

    Delayed G-CSF stimulation after PBSCT does not seem to modify the biological parameters of bone marrow recovery.

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    There are currently no recommendations indicating when stimulation should begin after autologous peripheral blood stem cell transplantation (PBSCT). We compared the outcome following between two treatment groups, in which daily granulocyte colony stimulating factor (G-CSF) administration began on either the fifth or the eighth day after PBSCT in lymphoma and myeloma patients. We studied eight clinical parameters: number of G-CSF injections, number of days of hospitalization, of red blood cell or platelet transfusions; days when body temperature exceeds 38°C; days of parenteral nutrition; weight loss and hospitalization costs. We studied also four biological parameters: number of CD34+ cells, days with leucocytes less than 1 × 10(9) /L, days with hemoglobin less than 90 g/L or with less than 50 × 10(9) /L of platelets. There were no statistical significant differences between the study arms. It seems that delayed stimulation by G-CSF after PBSCT is safety and does not seem to modify bone marrow recovery timing
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