6,077 research outputs found
Carbonate chemistry and dissolved oxygen in the Gulf of Papagayo (Culebra Bay), Costa Rica
No full textSalinity, pH, sea water temperature (SWT) and pCO2 was measured at a water-depth of ~ 3 m at the Marina Papagayo (85°39'21.41"W; 10°32'32.89"N) in Costa Rica in April 2009. SWT and the pCO2 was measured by using SUNDANS, which was developed by "Marine Analytics and Data" (MARIANDA, Germany, www.marianda.com) according to the recommendations of the 2002 underway pCO2 system workshop in Miami, Florida. Salinity and the dissolved oxygen concentrations were determined by using WTW probes (Cond3310 and Multi 340i). The pH was measured using an Orion ROSS electrode and an Orion StarTM. The Orion ROSS electrode was calibrated by using NBS standards and re-calibrated to total scale by using the RCM standards (Batch 82: http://andrew.ucsd.edu/co2qc/). Omega_Aragonite (Ωa), DIC, and TA were calculated based on the ƒCO2 and the pH. Rixen et al. 2012 provides more detailed information
Eleven month high resolution pollen and spore sedimentation record off SW Java in the Indian Ocean
No full textSettling particles collected in a sediment trap 60 km off SW Java in the Indian Ocean at a 2200 m deep site, about 830 m above the sea floor, between December 2001 and November 2002 (intervals of 16 days for 11 months) were analyzed for the abundance and taxa composition of pollen and spores. Several factors control their deposition such as the monsoon-driven reversal of the wind directions and ocean currents as well as flowering periods. Long distance transport plays a particular role during the monsoon seasons. During the NW monsoon (mid-December-beginning of March), maxima of Picea type, Alnus, Pinus and Quercus pollen occur in the trap samples, which correspond to wind and marine currents coming from the north, probably the Equatorial Counter Current and Southern Java Current, transporting pollen from the southern part of continental Asia and Sumatra to the research area. During the SE monsoon (end of July-mid-November), an increase of pollen originating from southeast Indonesia and Australia was observed. Pollen grains were probably transported by the South Equatorial Current and partly by the Leeuwin Current. Casuarina and, in part, Eucalyptus are most abundant during this period. During the intermonsoon period, assemblages are mainly composed of pollen originating from West Java. Maxima of some pollen taxa, such as Elaeocarpus, Myrica, Dacryccupus type, Casuarina, Eucalyptus and Podocarpus type probably reflect their flowering periods. The transportation time from the pollen source area to the sediment trap is about 1-2 months. The extrapolated pollen accumulation rate of the marine sediment trap would be about 1670 grains/cm(2)/yr. The trap collected low concentrations of mangrove pollen, which might be the result of the strong destruction of the mangrove belt in Java during recent decades. High values of Poaceae pollen are probably related to the land use, forest canopy opening and development of the secondary vegetation in West Java. The majority of the pollen and spores collected by the sediment trap reflects the vegetation of SW Java, but long distance transport, in particular by the marine currents during the SE and NE monsoons, needs to be considered when interpreting marine pollen records off SW Java in the eastern Indian Ocean. (C) 2014 Elsevier B.V. All rights reserved
Do dolphins benefit from nonlinear mathematics when processing their sonar returns?
No full textAn interview with author Tim Leighton about the paper
Opportunities for linking young surveyors across professional surveying member organisations and FIG
No full textTim Di Muzio on 'Sabotage'
No full textIn a series of essays published in 2013 and 2014 on capitaspower.com, political economist Tim Di Muzio explored the concept of ‘sabotage’ as it applies to capitalist power. I recently rediscovered these essays and was so impressed by them that I have reposted them here as a single piece.
About the author: Tim Di Muzio is a researcher at the University of Wollongong. He is the author of numerous books, including Debt as power, Carbon capitalism, and The 1% and the Rest of us
1996-1997 Tim Gautreaux
No full textTim Gautreaux is the author of three novels and two earlier short story collections. His work has appeared in The New Yorker, The Best American Short Stories, The Atlantic, Harper’s, and GQ. After teaching for thirty years at Southeastern Louisiana University, he now lives, with his wife, in Chattanooga, Tennessee. (Photo credit: Randy Bergeron)https://egrove.olemiss.edu/grisham_res/1023/thumbnail.jp
Raw data of physical oceanography during RV HEINCKE cruise HE454
No full textRaw physical oceanography data was acquired by a ship-based Seabird SBE911plus CTD-Rosette system onboard RV HEINCKE. The CTD was equipped with duplicate sensors for temperature (SBE3plus) and conductivity (SBE4) as well as one sensor for oxygen (SBE43). Additional sensors such as a WET Labs C-Star transmissometer, a WET Labs ECO-AFL fluorometer (FLRTD) and an altimeter (Teledyne Benthos PSA-916) were mounted to the CTD. The data was recorded using pre-cruise calibration coefficients. No correction, post-cruise calibration or quality control was applied. Processed profile data are available via the link below
Kohlenstoffpumpen im Benguela Auftriebsgebiet
No full textThe biological carbon (C) pump influences the flux of carbon dioxide (CO2) between the ocean and the atmosphere by carbon assimilation during the photosynthesis of particulate organic carbon (POC) and the precipitation of calcium carbonate particles (PIC). Regions of intense biological carbon pumping are eastern boundary upwelling systems, among which the Benguela upwelling system (BUS) is the most productive but the least studied one.
The main objective of this thesis is to investigate the functioning of the biological carbon pump in the northern BUS (NBUS), to assess whether the BUS is a net source or sink for carbon and to give basis for evaluating potential responses of the BUS to global change.
Dissolved inorganic nutrient and carbonate chemistry data was raised and used to study the spatio-temporal variability of the remineralisation ratios of C, nitrogen (N) and phosphate (P) (C/N/P) with emphasis on the variability of N deficiency, which is a major factor that limits the production of POC. Records of annual particle fluxes along with hydrographical data were obtained by a mooring on the shelf off Walvis Bay. In conjunction with meteorological records, these data were used to investigate the influence of upwelling on the particle fluxes with a focus on the factors that control the export of POC and PIC on the shelf. Furthermore, carbonate chemistry data allow to determine the variability of the carbonate saturation state (Ω) which influences calcification, growth and survival in many marine calcifying organisms. Along with patterns of air-sea CO2 fluxes, these results were used to evaluate the C source-sink function of the BUS.
The results show that the release of C, N and P in the course of organic matter decomposition follows the Redfield stoichiometry of C/N/P of 106/16/1 in the oxygenated water column. However, N loss and P input, which occur in sub- and anoxic bottom waters overlying the mud belt of the Namibian shelf, lower the N/P to <16 in upwelling intermediate water. Together, these processes result in an N deficiency (-N*), equivalent to a relative P excess (+P*), which surfaces and extends to the adjacent hemipelagic ocean. The results suggest that the magnitude of exported P* is not only controlled by the degree of local O2 deficiency on the shelf, but as well by the amount of remotely supplied N* excess (N/P >16, +N*). The findings point to a mechanism which replenishes the N* deficiency on the NBUS shelf and thereby counteracts the N limitation that hampers the N-driven CO2 drawdown of the biological carbon pump in the NBUS.
The combined results of hydrographical, meteorological and particle flux data show that even comparatively weak upwelling of high SACW fractions fuels higher POC fluxes (>91 g POC m-2 yr-1) than intense upwelling of Eastern South Atlantic Central Water (ESACW). This reflects the higher nutrient inventory of SACW compared to ESACW, among other factors. The results further indicate that the POC export on the shelf is dominated by diatom productivity. The decomposition of the basically diatomaceous organic matter causes very low Ω (ΩAmin = 0.7, ΩCmin = 1.2) and high silicate concentrations in ascending sub-thermocline waters. This corrosive water reduces the PIC formation in the surface and its export (11 g PIC m-2 yr-1) on the Namibian shelf, relative to the high, diatom-dominated POC formation and export (66 g POC m-2 yr-1). This results in a high POC/PIC ratio of 6 in sinking matter, pointing to an efficient CO2 uptake by the coastal biological carbon pump. Towards the slope and the open ocean, an increasing contribution of PIC to POC export is enabled by rising Ω and depleted silicate concentrations, providing an ecological advantage for carbonate producers. As indicated by the results of P* in offshore waters, the biological pump’s efficiency in the offshore sector of the upwelling system is hampered by N limitation, thus lowering the N-driven CO2 drawdown. In terms of nutrient stoichiometry, the unused P* constitutes a leakage of potential C export that accounts for ~25 % of the total N-driven potential export fluxes of ~98 Tg C yr-1 of the NBUS. Clearly, NBUS productivity suffers from the impact of N loss or P gain incurred from suboxic conditions on the shelf.
The CO2 emission patterns reveal that the NBUS is a CO2 source in the order of 13.6 Tg C yr-1, likely reflecting the N deficit in upwelling subsurface water. The southern BUS (SBUS) is a significant sink of -3.4 Tg C yr-1 and reflects the higher contribution of biologically unused, preformed nutrients in upwelling source waters of the SBUS compared to the NBUS.
Adding the combined POC and PIC export sink of (-66 and -11 g C m-2 yr-1 to the CO2 emissions of the NBUS (+71 g C m-2 yr-1) indicates that the NBUS is a small net sink of -6 g C m-2 yr-1
First person - Tim Petzold
No full textFirst Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping researchers promote themselves alongside their papers. Tim Petzold is first author on ‘ Connexin 41.8 governs timely haematopoietic stem and progenitor cell specification’, published in BiO. Tim conducted the research described in this article while a PhD student in Julien Bertrand's lab at the Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Switzerland. He is now a postdoc in the lab of Holger Gerhardt at the Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany, investigating developmental biology – previously his focus was on how blood stem cells develop and now it has shifted to how the vascular system develops
Sea water temperature (SWT) and pCO2 measurements in the Gulf of Papagayo (Culebra Bay), Costa Rica
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