161 research outputs found

    Opportunistic Sampling at a Deep-water Synthetic Drilling Fluid Discharge Site in the Gulf of Mexico

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    Two opportunistic benthic surveys were conducted at an offshore semisubmersible oil drilling rig located in 565 m of water on the continental slope of the Gulf of Mexico to determine the extent of synthetic-based drilling fluid (Petrofree LE) concentrations in surrounding sediments and the composition of the associated macrofauna and megafauna communities. Sediment concentrations of Petrofree LE ranged from 89 to 198,320 μg/g in surficial sediments (0-2 cm) and from 4 to 85,821 mg/g in the 2-5 cm stratum. The highest Petrofree LE concentrations were located 50-75 m northeast of the discharge site, a phenomenon that may have been related to surface and midwater currents in the vicinity of the rig. Although no direct quantitative measures of in situ degradation are available, high concentrations of Petrofree LE relative to discharge periodicity suggest lower than anticipated rates at this deep-water site. Between July 1997 and March 1998, the densities of polychaetes and gastropods increased sharply in the study area. In March, polychaete (primarily dorvilleids) density, gastropod density, and Petrofree concentrations were all significantly higher northeast of the drill site compared with southwest. Polychaete and gastropod densities northeast of the drill site were roughly 3,600 and 3,000 times higher than those reported in eastern and western areas of the northern Gulf of Mexico at similar depths, respectively

    Centers for Oceans and Human Health : a unified approach to the challenge of harmful algal blooms

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    © 2008 Author et al. This is an open access article distributed under the terms of the Creative Commons Attribution License The definitive version was published in Environmental Health 7 (2008): S2, doi:10.1186/1476-069X-7-S2-S2.Harmful algal blooms (HABs) are one focus of the national research initiatives on Oceans and Human Health (OHH) at NIEHS, NOAA and NSF. All of the OHH Centers, from the east coast to Hawaii, include one or more research projects devoted to studying HAB problems and their relationship to human health. The research shares common goals for understanding, monitoring and predicting HAB events to protect and improve human health: understanding the basic biology of the organisms; identifying how chemistry, hydrography and genetic diversity influence blooms; developing analytical methods and sensors for cells and toxins; understanding health effects of toxin exposure; and developing conceptual, empirical and numerical models of bloom dynamics. In the past several years, there has been significant progress toward all of the common goals. Several studies have elucidated the effects of environmental conditions and genetic heterogeneity on bloom dynamics. New methods have been developed or implemented for the detection of HAB cells and toxins, including genetic assays for Pseudo-nitzschia and Microcystis, and a biosensor for domoic acid. There have been advances in predictive models of blooms, most notably for the toxic dinoflagellates Alexandrium and Karenia. Other work is focused on the future, studying the ways in which climate change may affect HAB incidence, and assessing the threat from emerging HABs and toxins, such as the cyanobacterial neurotoxin β-N-methylamino-L-alanine. Along the way, many challenges have been encountered that are common to the OHH Centers and also echo those of the wider HAB community. Long-term field data and basic biological information are needed to develop accurate models. Sensor development is hindered by the lack of simple and rapid assays for algal cells and especially toxins. It is also critical to adequately understand the human health effects of HAB toxins. Currently, we understand best the effects of acute toxicity, but almost nothing is known about the effects of chronic, subacute toxin exposure. The OHH initiatives have brought scientists together to work collectively on HAB issues, within and across regions. The successes that have been achieved highlight the value of collaboration and cooperation across disciplines, if we are to continue to advance our understanding of HABs and their relationship to human health.This work was funded through grants from the NSF/NIEHS Centers for Oceans and Human Health, NIEHS P50 ES012742 and NSF OCE-043072 (DLE and DMA), NSF OCE04-32479 and NIEHS P50 ES012740 (PB and RRB), NSF OCE-0432368 and NIEHS P50 ES12736 (LEB), NIEHS P50 ES012762 and NSF OCE-0434087 (RCS, KAL, MSP, MLW, and KAH). Additional support was provided by the ECOHAB Grant program NSF Grant OCE-9808173 and NOAA Grant NA96OP0099 (DMA), NOAA OHHI NA04OAR4600206 (RRB) and Washington State Sea Grant NA16RG1044 (RCS). KAL and VLT were supported in part by the West Coast Center for Oceans and Human Health (WCCOHH) as part of the NOAA Oceans and Human Health Initiative

    The SPARC Toroidal Field Model Coil Program

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    The SPARC Toroidal Field Model Coil (TFMC) Program was a three-year effort between 2018 and 2021 that developed novel Rare Earth Yttrium Barium Copper Oxide (REBCO) superconductor technologies and then successfully utilized these technologies to design, build, and test a first-in-class, high-field (~20 T), representative-scale (~3 m) superconducting toroidal field coil. With the principal objective of demonstrating mature, large-scale, REBCO magnets, the project was executed jointly by the MIT Plasma Science and Fusion Center (PSFC) and Commonwealth Fusion Systems (CFS). The TFMC achieved its programmatic goal of experimentally demonstrating a large-scale high-field REBCO magnet, achieving 20.1 T peak field-on-conductor with 40.5 kA of terminal current, 815 kN/m of Lorentz loading on the REBCO stacks, and almost 1 GPa of mechanical stress accommodated by the structural case. Fifteen internal demountable pancake-to-pancake joints operated in the 0.5 to 2.0 nOhm range at 20 K and in magnetic fields up to 12 T. The DC and AC electromagnetic performance of the magnet, predicted by new advances in high-fidelity computational models, was confirmed in two test campaigns while the massively parallel, single-pass, pressure-vessel style coolant scheme capable of large heat removal was validated. The REBCO current lead and feeder system was experimentally qualified up to 50 kA, and the crycooler based cryogenic system provided 600 W of cooling power at 20 K with mass flow rates up to 70 g/s at a maximum design pressure of 20 bar-a for the test campaigns. Finally, the feasibility of using passive, self-protection against a quench in a fusion-scale NI TF coil was experimentally assessed with an intentional open-circuit quench at 31.5 kA terminal current.Comment: 17 pages 9 figures, overview paper and the first of a six-part series of papers covering the TFMC Progra

    The SPARC Toroidal Field Model Coil Program

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