1,721,289 research outputs found
Student sermon: Ross, Vance D.
No full textInterdenominational Theological Center student Vance D. Ross delivers a sermon titled Giving Help Unselfishly.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the National Endowment for Humanities - Humanities Collections and Reference Resources Implementation Project Grant in supporting the processing and digitization of a number of its major archival collections as part of the project: Spreading the Word: Expanding Access to African American Religious Archival Collections at the Atlanta University Center Robert W. Woodruff Library.</em
New neodymium isotope data quantify Nile involvement in Mediterranean anoxic episodes
No full textThe development of widespread anoxic conditions in the deep oceans is evidenced by the accumulation and preservation of organic-carbon–rich sediments, but its precise cause remains controversial. The two most popular hypotheses involve (1) circulation-induced increased stratification resulting in reduced oxygenation of deep waters or (2) enhanced productivity in the surface ocean, increasing the raining down of organic matter and overwhelming the oxic remineralization potential of the deep ocean. In the periodic development of deep-water anoxia in the Pliocene–Pleistocene Mediterranean Sea, increased riverine runoff has been implicated both as a source for nutrients that fuel enhanced photic-zone productivity and a source of a less dense freshwater cap leading to reduced circulation, basin-wide stagnation, and deep-water oxygen starvation. Monsoon-driven increases in Nile River discharge and increased regional precipitation due to enhanced westerly activity—two mechanisms that represent fundamentally different climatic driving forces—have both been suggested as causes of the altered freshwater balance. Here we present data that confirm a distinctive neodymium (Nd) isotope signature for the Nile River relative to the Eastern Mediterranean—providing a new tracer of enhanced Nile outflow into the Mediterranean in the past. We further present Nd isotope data for planktonic foraminifera that suggest a clear increase in Nile discharge during the central intense period of two recent anoxic events. Our data also suggest, however, that other regional freshwater sources were more important at the beginning and end of the anoxic events. Taken at face value, the data appear to imply a temporal link between peaks in Nile discharge and enhanced westerly activity
Expression of phosphatidylethanolamine N-methyltransferase in Yoshida Ascites Hepatoma Cells and the Livers of Host Rats
No full textNd/Ca ratios in plankton-towed and core top foraminifera: Confirmation of the water column acquisition of Nd
Full text linkPlanktic foraminifera have been used as recorders of the neodymium (Nd) isotopic composition ofseawater, although there is still controversy over the precise provenance of the Nd signal. We present anextensive, multispecific plankton tow Nd/Ca data set from several geographic locations (SE Atlantic, NEAtlantic, Norwegian Sea, and western Mediterranean), together with core top samples from theMediterranean region. The range of Nd/Ca ratios in plankton-towed foraminifera, cleaned only of organicmaterial, from all regions (0.01–0.7 umol/mol), is similar to previously published analyses of sedimentaryforaminifera cleaned using both oxidative and reductive steps, with distribution coefficients (Kd) rangingbetween 4 and 302. For the Mediterranean, where core top and plankton tow data are both available, therange for plankton tows (0.05–0.7 umol/mol) is essentially identical to that for the core tops (0.1–0.5 umol/mol). Readsorption of Nd during cleaning is ruled out by the fact that the plankton tow samplesunderwent only an oxidative cleaning process. We find a relationship between manganese (Mn) and Nd inplankton tow samples that is mirrored by a similar correlation in core top samples. This relationshipsuggests that Fe-Mn coatings are of negligible importance to the Nd budgets of foraminifera as the Nd/Mnratio it implies is over an order of magnitude greater than that seen in other Fe-Mn oxide phases. Rather,since both plankton tows and core tops present a similar behavior, the Nd/Mn relationship must originate inthe upper water column. The data are consistent with the acquisition of Nd and Mn from the water columnby binding to organic material and the fact that intratest organic material is shielded from both aggressivecleaning and diagenetic processes. Collectively, the results help to explain two abiding puzzles about Nd insedimentary planktic foraminifera: their high REE contents and the fact that they record a surface water Ndisotopic signal, regardless of the cleaning procedure used
The consequence of Quaternary changes in chemical weathering rate for ocean chemistry (abstract of paper presented at: 17th Annual V. M. Goldschmidt Conference Cologne, Germany August 2007)
No full textQuaternary weathering rates and marine geochemical budgets (abstract of paper presented at: 18th Annual V. M. Goldschmidt Conference Vancouver, Canada, July 2008)
No full textNd data for the Nile, eastern Mediterranean and forams document Nile outflow increases during S1 and S5 (abstract of paper presented at 12th Annual V.M. Goldschmidt Conference, Davos, Switzerland, August 18-23, 2002)
No full textNeodymium isotope data for foraminifera indicates increased Nile outflow during Mediterranean anoxic events (abstract of paper presented at AGU Fall Meeting, San Francisco, CA, 10-14 Dec 2001)
No full textBreaching the North African watershed: driver for Mediterranean anoxia? (abstract of paper presented at: 17th Annual V. M. Goldschmidt Conference Cologne, Germany August 2007)
No full text- …
