Journal articles: 'Iode – Isotopes'

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QUAIJTAAL, WILLEMIJN, STEVEN TESSEUR, TIMME H. DONDERS, PHILIPPE CLAEYS, and STEPHEN LOUWYE. "A revised and improved age model for the middle Miocene part of IODP Site U1318 (Porcupine Basin, offshore southwestern Ireland)." Geological Magazine 155, no. 5 (January 30, 2017): 1105–16. http://dx.doi.org/10.1017/s0016756816001278.

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AbstractIntegrated Ocean Drilling Program Leg 307 Site U1318 is one of the few relatively complete middle Miocene drillcores from the North Atlantic (Porcupine Basin, offshore southwestern Ireland). Using benthic foraminiferal stable carbon and oxygen isotopes, the existing age model for Site U1318 was improved. The stable isotope record displays globally recognized isotope events, used to revise the existing magnetostratigraphy-based age model. Two intervals contained misidentified magnetochrons which were corrected. The sampled interval now has a refined age of 12.75–16.60 Ma with a temporal resolution of c. 29 ka.

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Hodell, David A., and James E. T. Channell. "Mode transitions in Northern Hemisphere glaciation: co-evolution of millennial and orbital variability in Quaternary climate." Climate of the Past 12, no. 9 (September 7, 2016): 1805–28. http://dx.doi.org/10.5194/cp-12-1805-2016.

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Abstract. We present a 3.2 Myr record of stable isotopes and physical properties at IODP Site U1308 (reoccupation of DSDP Site 609) located within the ice-rafted detritus (IRD) belt of the North Atlantic. We compare the isotope and lithological proxies at Site U1308 with other North Atlantic records (e.g., sites 982, 607/U1313, and U1304) to reconstruct the history of orbital and millennial-scale climate variability during the Quaternary. The Site U1308 record documents a progressive increase in the intensity of Northern Hemisphere glacial–interglacial cycles during the late Pliocene and Quaternary, with mode transitions at ∼ 2.7, 1.5, 0.9, and 0.65 Ma. These transitions mark times of change in the growth and stability of Northern Hemisphere ice sheets. They also coincide with increases in vertical carbon isotope gradients between the intermediate and deep ocean, suggesting changes in deep carbon storage and atmospheric CO2. Orbital and millennial climate variability co-evolved during the Quaternary such that the trend towards larger and thicker ice sheets was accompanied by changes in the style, frequency, and intensity of millennial-scale variability. This co-evolution may be important for explaining the observed patterns of Quaternary climate change.

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Sissmann, Olivier, Roy Price, Marcus Elvert, Verena B. Heuer, Xavier Prieto, Christophe Monnin, Virgile Rouchon, et al. "Abiogenic formation of H2, light hydrocarbons and other short-chain organic compounds within the serpentinite mud volcanoes of the Marianna Trench." E3S Web of Conferences 98 (2019): 02011. http://dx.doi.org/10.1051/e3sconf/20199802011.

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Serpentinite-hosting mud volcanoes, located in the Marianna forearc subduction zone, were drilled during IODP Expedition 366. Recovered samples from Asùt Tesoru seamount provide new insights on the generation of organic matter in deep environments. Short-chain alcohols, volatile fatty acids and light hydrocarbons are produced within hyperalkaline pore fluids (pH 12.5) rich in H2. The stable isotope values of those species show heavy δ13C values, suggesting a formation process through Fischer-Tropsch-Type reactions. This close isotopic study brings new constraints on the reaction pathways leading to the formation of not only light hydrocarbons, but also of short-chain organic molecules. These compounds may serve as precursors of building blocks essential to life in deep oceanic settings.

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Pająk, Małgorzata. "Microwave enhanced synthesis of halogenated derivatives of L-tyrosine labeled with deuterium in aromatic ring." Journal of Radioanalytical and Nuclear Chemistry 326, no. 1 (August 28, 2020): 857–60. http://dx.doi.org/10.1007/s10967-020-07362-8.

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Abstract Three halogenated derivatives of L-tyrosine, selectively labeled with deuterium in aromatic ring, i.e., 3′-fluoro-[5′-2H]-, 3′-chloro-[5′-2H]-, and 3′-iodo-[2′,5′-2H2]-L-tyrosine, were synthesized using microwave assisted acid-catalyzed isotope exchange between 3′-fluoro-, 3′-chloro- and 3′-iodo-L-tyrosine and heavy water. The degree of deuterium incorporation was confirmed by 1H NMR spectroscopy. The spectroscopic data indicate that isotope exchange depends on the method of heating and the power of microwaves. The deuterium enrichment of 3′-fluoro-[5′-2H]- and 3′-chloro-[5′-2H]-L-tyrosine amounted to 70% and 60%, respectively, while for 3′-iodo-[2′,5′-2H2]-L-tyrosine this value was about 50% and 95% for the 2′- and 5′-position. The isotopomers were obtained in good chemical yields of 50–70%.

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De Vleeschouwer, David, Marion Peral, Marta Marchegiano, Angelina Füllberg, Niklas Meinicke, Heiko Pälike, Gerald Auer, et al. "Plio-Pleistocene Perth Basin water temperatures and Leeuwin Current dynamics (Indian Ocean) derived from oxygen and clumped-isotope paleothermometry." Climate of the Past 18, no. 5 (June 1, 2022): 1231–53. http://dx.doi.org/10.5194/cp-18-1231-2022.

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Abstract. The Pliocene sedimentary record provides a window into Earth's climate dynamics under warmer-than-present boundary conditions. However, the Pliocene cannot be considered a stable warm climate that constitutes a solid baseline for middle-of-the-road future climate projections. The increasing availability of time-continuous sedimentary archives (e.g., marine sediment cores) reveals complex temporal and spatial patterns of Pliocene ocean and climate variability on astronomical timescales. The Perth Basin is particularly interesting in that respect because it remains unclear if and how the Leeuwin Current sustained the comparably wet Pliocene climate in Western Australia, as well as how it influenced Southern Hemisphere paleoclimate variability. To constrain Leeuwin Current dynamics in time and space, this project obtained eight clumped-isotope Δ47 paleotemperatures and constructed a new orbitally resolved planktonic foraminifera (Trilobatus sacculifer) stable isotope record (δ18O) for the Plio-Pleistocene (4–2 Ma) interval of International Ocean Discovery Program (IODP) Site U1459. These new data complement an existing TEX86 record from the same site and similar planktonic isotope records from the Northern Carnarvon Basin (Ocean Drilling Program (ODP) Site 763 and IODP Site U1463). The comparison of TEX86 and Δ47 paleothermometers reveals that TEX86 likely reflects sea surface temperatures (SSTs) with a seasonal warm bias (23.8–28.9 ∘C), whereas T. sacculifer Δ47 calcification temperatures probably echo mixed-layer temperatures at the studied Site U1459 (18.9–23.2 ∘C). The isotopic δ18O gradient along a 19–29∘ S latitudinal transect, between 3.9 and 2.2 Ma, displays large variability, ranging between 0.5 ‰ and 2.0 ‰. We use the latitudinal δ18O gradient as a proxy for Leeuwin Current strength, with an inverse relationship between both. The new results challenge the interpretation that suggested a tectonic event in the Indonesian Throughflow as the cause for the rapid steepening of the isotopic gradient (0.9 ‰ to 1.5 ‰) around 3.7 Ma. The tectonic interpretation appears obsolete as it is now clear that the 3.7 Ma steepening of the isotopic gradient is intermittent, with flat latitudinal gradients (∼0.5 ‰) restored in the latest Pliocene (2.9–2.6 Ma). Still, the new analysis affirms that a combination of astronomical forcing of wind patterns and eustatic sea level controlled Leeuwin Current intensity. On secular timescales, a period of relatively weak Leeuwin Current is observed between 3.7 and 3.1 Ma. Notably, this interval is marked by cooler conditions throughout the Southern Hemisphere. In conclusion, the intensity of the Leeuwin Current and the latitudinal position of the subtropical front are both long-range effects of the same forcing: heat transport through the Indonesian Throughflow (ITF) valve and its propagation through Indian Ocean poleward heat transport. The common ITF forcing explains the observed coherence of Southern Hemisphere ocean and climate records.

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Matsuzaki, Kenji M., Hiroshi Nishi, Hiroki Hayashi, Noritoshi Suzuki, Babu R. Gyawali, Minoru Ikehara, Takuyuki Tanaka, and Reishi Takashima. "Radiolarian biostratigraphic scheme and stable oxygen isotope stratigraphy in southern Japan (IODP Expedition 315 Site C0001)." Newsletters on Stratigraphy 47, no. 1 (April 1, 2014): 107–30. http://dx.doi.org/10.1127/0078-0421/2014/0044.

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Derdau, Volker. "Radioaktive Isotope des Wasserstoffs, Kohlenstoffs und Iods." Chemie in unserer Zeit 53, no. 4 (April 17, 2019): 224–31. http://dx.doi.org/10.1002/ciuz.201800866.

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Wankel, S. D., C. Buchwald, W. Ziebis, C. B. Wenk, and M. F. Lehmann. "Nitrogen cycling in the subsurface biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic." Biogeosciences Discussions 12, no. 16 (August 21, 2015): 13545–91. http://dx.doi.org/10.5194/bgd-12-13545-2015.

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Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, the cycling and availability of N is a central factor governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3−) from a site in the oligotrophic North Atlantic (IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3− accumulates far above bottom seawater concentrations (∼ 21 μM) throughout the sediment column (up to ∼ 50 μM) down to the oceanic basement as deep as 90 mbsf, reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3− isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide isotope evidence for expanded zones of co-ocurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR and δ18ONTR), as well as the isotope effect for denitrification (15&varepsilon;DNF), parameters with high relevance to global ocean models of N cycling. Estimated values of δ15NNTR were generally lower than previously reported δ15N values for sinking PON in this region. We suggest that these values can be related to sedimentary N-fixation and remineralization of the newly fixed organic N. Values of δ18ONTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ18ONTR values were elevated, suggesting incorporation of 18O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH4+ and NO2− oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supply a large fraction of the biomass and organic substrate for heterotrophy in these sediments, supplementing the small organic matter pool derived from the overlying euphotic zone. This work sheds new light on an active nitrogen cycle operating, despite exceedingly low carbon inputs, in the deep sedimentary biosphere.

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Wankel, S. D., C. Buchwald, W. Ziebis, C. B. Wenk, and M. F. Lehmann. "Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic." Biogeosciences 12, no. 24 (December 21, 2015): 7483–502. http://dx.doi.org/10.5194/bg-12-7483-2015.

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Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3−) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program – IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (~ 21 μM) throughout the sediment column (up to ~ 50 μM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3- isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR (NTR, referring to nitrification) and δ18ONTR), as well as the isotope effect for denitrification (15&varepsilon;DNF) (DNF, referring to denitrification), parameters with high relevance to global ocean models of N cycling. Estimated values of δ15NNTR were generally lower than previously reported δ15N values for sinking particulate organic nitrogen in this region. We suggest that these values may be, in part, related to sedimentary N2 fixation and remineralization of the newly fixed organic N. Values of δ18ONTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ18ONTR values were elevated, suggesting incorporation of 18O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH4+ and NO2− oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supplies a large fraction of the biomass and organic substrate for heterotrophy in these sediments, supplementing the small organic-matter pool derived from the overlying euphotic zone. This work sheds new light on an active nitrogen cycle operating, despite exceedingly low carbon inputs, in the deep sedimentary biosphere.

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Bolla, Ratna Sekhar, Narasimha Murthy Gandikota, and Ivaturi Venkata Kasi Viswanath. "Synthesis of Deuterium Labeled 5, 5-Dimethyl-3-(α, α, α-trifluoro-4-nitro-m-tolyl) Hydantoin." Current Radiopharmaceuticals 12, no. 1 (March 4, 2019): 82–87. http://dx.doi.org/10.2174/1874471012666181130162731.

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Objective: Stable and non-radioactive isotope labeled compounds gained significance in recent drug discovery and other various applications such as bio-analytical studies. The modern bioanalytical techniques can study the adverse therapeutic effects of drugs by comparing isotopically labeled internal standards. A well-designed labeled compound can provide high-quality information about the identity and quantification of drug-related compounds in biological samples. This information can be very useful at key decision points in drug development. In this study, we tried to synthesize Nilutamide- d6 which can be useful to study the adverse effects of Nilutamide, and based on these can modify or widen the new drug derivatives. Nilutamide is a nonsteroidal antiandrogen which is used in the treatment of prostate cancer. The aim of this study was to develop a synthetic approach to prepare deuterium labeled [2H6]-5, 5-dimethylimidazolidine-2, 4-dione and [2H6]-nilutamide. Methods: Since nilutamide is a derivative of hydantoin, it involves the synthesis of Dimethylhydantoin via Bucherer-Bergs hydantoin synthesis, followed by oxidative N-arylation with 4-iodo-1-nitro-2- (trifluoromethyl) benzene. Conclusion: We successfully synthesized [2H6]-nilutamide and [2H6]-dimethylhydantoin with good isotopic purity, measured to be of adequate quality for use as internal standards in bio-analytical studies. A brief mechanistic study of Bucherer-Bergs hydantoin reaction was carried and the reason for possible H/D exchange was explained.

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Smith, Peter James, Kanchugarakoppal S. Rangappa, and Kenneth Charles Westaway. "Secondary α-deuterium kinetic isotope effects for the E2 reaction of the 2-phenylethyl halides with tert-butoxide ion in tert-butyl alcohol." Canadian Journal of Chemistry 63, no. 1 (January 1, 1985): 100–102. http://dx.doi.org/10.1139/v85-017.

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Secondary α-deuterium kinetic isotope effects have been determined for the elimination reactions of 2-phenylethyl halides with tert-butoxide in tert-butyl alcohol at 40 °C in the presence and absence of the crown ether 18C6. The second-order rate constant k2 and the normal (kH/kD)α effect remained constant when the tert-butoxide concentration was varied for reaction of the iodo and bromo compounds. However, both the magnitude of k2 and the secondary α-deuterium isotope effect were significantly dependent on [t-BuO−] when chlorine and fluorine are the leaving groups. It is noteworthy that (kH/kD)α is inverse for the reaction of both the chloro and fluoro compounds at "low" base concentrations and normal at "high" base concentrations. These results are discussed in terms of both syn- and anti-elimination pathways promoted by various associated and dissociated base species. It is suggested that the (kH/kD)α effect may be useful as a criterion for determining the stereochemistry of E2 elimination reactions.

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Hodell, D. A., L. Lourens, D. A. V. Stow, J. Hernández-Molina, and C. A. Alvarez Zarikian. "The "Shackleton Site" (IODP Site U1385) on the Iberian Margin." Scientific Drilling 16 (November 5, 2013): 13–19. http://dx.doi.org/10.5194/sd-16-13-2013.

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Abstract. Nick Shackleton's research on piston cores from the Iberian margin highlighted the importance of this region for providing high-fidelity records of millennial-scale climate variability, and for correlating climate events from the marine environment to polar ice cores and European terrestrial sequences. During the Integrated Ocean Drilling Program (IODP) Expedition 339, we sought to extend the Iberian margin sediment record by drilling with the D/V JOIDES Resolution. Five holes were cored at Site U1385 using the advanced piston corer (APC) system to a maximum depth of ~155.9 m below sea floor (m b.s.f.). Immediately after the expedition, cores from all holes were analyzed by core scanning X-ray fluorescence (XRF) at 1 cm spatial resolution. Ca/Ti data were used to accurately correlate from hole-to-hole and construct a composite spliced section, containing no gaps or disturbed intervals to 166.5 m composite depth (mcd). A low-resolution (20 cm sample spacing) oxygen isotope record confirms that Site U1385 contains a continuous record of hemipelagic sedimentation from the Holocene to 1.43 Ma (Marine Isotope Stage 46). The sediment profile at Site U1385 extends across the middle Pleistocene transition (MPT) with sedimentation rates averaging ~10 cm kyr−1. Strong precession cycles in colour and elemental XRF signals provide a powerful tool for developing an orbitally tuned reference timescale. Site U1385 is likely to become an important type section for marine–ice–terrestrial core correlations and the study of orbital- and millennial-scale climate variability.

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Ekaykin, Alexey A., Diana O. Vladimirova, Vladimir Y. Lipenkov, and Valérie Masson-Delmotte. "Climatic variability in Princess Elizabeth Land (East Antarctica) over the last 350 years." Climate of the Past 13, no. 1 (January 16, 2017): 61–71. http://dx.doi.org/10.5194/cp-13-61-2017.

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Abstract. We use isotopic composition (δD) data from six sites in Princess Elizabeth Land (PEL) in order to reconstruct air temperature variability in this sector of East Antarctica over the last 350 years. First, we use the present-day instrumental mean annual surface air temperature data to demonstrate that the studied region (between Russia's Progress, Vostok and Mirny research stations) is characterized by uniform temperature variability. We thus construct a stacked record of the temperature anomaly for the whole sector for the period of 1958–2015. A comparison of this series with the Southern Hemisphere climatic indices shows that the short-term inter-annual temperature variability is primarily governed by the Antarctic Oscillation (AAO) and Interdecadal Pacific Oscillation (IPO) modes of atmospheric variability. However, the low-frequency temperature variability (with period > 27 years) is mainly related to the anomalies of the Indian Ocean Dipole (IOD) mode. We then construct a stacked record of δD for the PEL for the period of 1654–2009 from individual normalized and filtered isotopic records obtained at six different sites (PEL2016 stacked record). We use a linear regression of this record and the stacked PEL temperature record (with an apparent slope of 9 ± 5.4 ‰ °C−1) to convert PEL2016 into a temperature scale. Analysis of PEL2016 shows a 1 ± 0.6 °C warming in this region over the last 3 centuries, with a particularly cold period from the mid-18th to the mid-19th century. A peak of cooling occurred in the 1840s – a feature previously observed in other Antarctic records. We reveal that PEL2016 correlates with a low-frequency component of IOD and suggest that the IOD mode influences the Antarctic climate by modulating the activity of cyclones that bring heat and moisture to Antarctica. We also compare PEL2016 with other Antarctic stacked isotopic records. This work is a contribution to the PAGES (Past Global Changes) and IPICS (International Partnerships in Ice Core Sciences) Antarctica 2k projects.

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Singh, Vikram Pratap, Shivani Pathak, and Rahul Dwivedi. "Reduction in the Strength of Agulhas Current During Quaternary: Planktic Foraminiferal Records for 1.2 Million Years from IODP Hole U-1474A." Journal of Climate Change 9, no. 4 (December 11, 2023): 45–52. http://dx.doi.org/10.3233/jcc230031.

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The Agulhas Current (AC) had been quite variable during the Quaternary Period, which not only impacted the Agulhas Leakage (AL) but also caused changes in the AMOC. To study the changes in the strength of AC, planktic foraminiferal census count and stable oxygen isotope data from the IODP Hole U-1474A were generated for the last 1.2 million years (My). We recorded significant variations in the abundance of climate-sensitive species, which were grouped according to their ecological preference as warm tropical-subtropical Agulhas Fauna (AF), temperate-subpolar Southern Ocean Fauna (SOF), stable oxygen isotope records and the Subtropical Front (STF) Index. The correlation of these records suggests that the strength of AC reduced during seven intervals during the last 1.2 My, in response to cooling climate, which led to the northward shift of STF. The studied interval was divided into three periods of MPT, MPT-MBE and post-MBE events. The AC was strongest after the Mid-Brunhes Event (0.43 Ma) as compared to the Mid-Pleistocene Transition (MPT) and post-MPT to MBE intervals.

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Koppers, A. A. P., T. Yamazaki, and J. Geldmacher. "IODP Expedition 330: Drilling the Louisville Seamount Trail in the SW Pacific." Scientific Drilling 15 (March 1, 2013): 11–22. http://dx.doi.org/10.5194/sd-15-11-2013.

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Deep-Earth convection can be understood by studying hotspot volcanoes that form where mantle plumes rise up and intersect the lithosphere, the Earth's rigid outer layer. Hotspots characteristically leave age-progressive trails of volcanoes and seamounts on top of oceanic lithosphere, which in turn allow us to decipher the motion of these plates relative to "fixed" deep-mantle plumes, and their (isotope) geochemistry provides insights into the long-term evolution of mantle source regions. However, it is strongly suggested that the Hawaiian mantle plume moved ~15° south between 80 and 50 million years ago. This raises a fundamental question about other hotspot systems in the Pacific, whether or not their mantle plumes experienced a similar amount and direction of motion. Integrated Ocean Drilling Program (IODP) Expedition 330 to the Louisville Seamounts showed that the Louisville hotspot in the South Pacific behaved in a different manner, as its mantle plume remained more or less fixed around 48°S latitude during that same time period. Our findings demonstrate that the Pacific hotspots move independently and that their trajectories may be controlled by differences in subduction zone geometry. Additionally, shipboard geochemistry data shows that, in contrast to Hawaiian volcanoes, the construction of the Louisville Seamounts doesn’t involve a shield-building phase dominated by tholeiitic lavas, and trace elements confirm the rather homogenous nature of the Louisville mantle source. Both observations set Louisville apart from the Hawaiian-Emperor seamount trail, whereby the latter has been erupting abundant tholeiites (characteristically up to 95% in volume) and which exhibit a large variability in (isotope) geochemistry and their mantle source components. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.02.2013" target="_blank">10.2204/iodp.sd.15.02.2013</a>

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Voelker, A. H. L., T. Rodrigues, R. Stein, J. Hefter, K. Billups, D. Oppo, J. McManus, and J. O. Grimalt. "Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes: Does Marine Isotope Stage 11 stand out?" Climate of the Past Discussions 5, no. 3 (June 3, 2009): 1553–607. http://dx.doi.org/10.5194/cpd-5-1553-2009.

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Abstract. New planktonic stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699) are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9–14 (300–540 ka). Together the study sites reflect western and eastern basin boundary currents as well as north to south transect sampling of subpolar and transitional water masses. Planktonic δ18O records indicate that during peak interglacial MIS 9 and 11 hydrographic conditions were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of which is slightly warmer. Enhanced subsurface northward heat flux in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktonic foraminifer species. MIS 13 was generally colder and more variable than the younger interglacials. The greatest differences between the sites existed during the glacial inceptions and glacials. Then a north-south trending hydrographic front separated the nearshore and offshore waters off Portugal. While offshore waters originated from the North Atlantic Drift as indicated by the similarities between the records of IODP Site U1313, ODP Site 980 and MD01-2446, nearshore waters as recorded in core MD03-2699 derived from the Azores Current and thus the subtropical gyre. A strong Azores Current influence is seen especially during MIS 12, when SST dropped significantly only during the Heinrich-type ice-rafting event at the onset of Termination V. Given the subtropical overprint on Portuguese nearshore sites such as MD03-2699 and MD01-2443 caution needs to be taken to interpret their records as basin-wide climate signals.

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Voelker, Antje H. L., Teresa Rodrigues, Samanta Trotta, Maria Marino, and Henning Kuhnert. "A Southern Portuguese Margin Perspective of Marine Isotope Stage 47—An Interglacial in the 41 kyr World." Atmosphere 13, no. 9 (August 28, 2022): 1378. http://dx.doi.org/10.3390/atmos13091378.

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In order to better understand interglacial climate variability within the 41 kyr world, we produced high-resolution climate records for interglacial Marine Isotope Stage (MIS) 47 (1424–1452 ka) at IODP Site U1387 (36°48′ N, 7°43′ W) on the southern Portuguese margin. Using benthic and planktonic foraminifera stable isotope records, Uk’37 sea-surface temperature (SST), and plankton assemblage data we investigated Mediterranean Outflow Water (MOW) and surface water conditions. The MOW-level records indicate a poorly ventilated and sluggish bottom current during the MIS 48/MIS 47 transition in association with the insolation maximum, whereas a well-ventilated MOW formed a contourite layer during the second insolation maximum. The benthic δ18O record shows a fairly abrupt change during the deglaciation of MIS 48, while the surface waters experienced a terminal stadial event that was associated with initial cooling and freshening followed by stepwise warming until interglacial SST was reached at 1450 ka. Interglacial conditions with SST of 24 °C or higher persisted until 1427 ka, although warm SST prevailed into MIS 46. The persistent and prolonged warmth is attributed to a northward expansion of the subtropical gyre during MIS 47 as reflected by the dominance of subtropical-tropical planktonic foraminifera species and the presence of warm water coccolithophores taxa.

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Frieling, Joost, Emiel P. Huurdeman, Charlotte C. M. Rem, Timme H. Donders, Jörg Pross, Steven M. Bohaty, Guy R. Holdgate, Stephen J. Gallagher, Brian McGowran, and Peter K. Bijl. "Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia." Journal of Micropalaeontology 37, no. 1 (February 13, 2018): 317–39. http://dx.doi.org/10.5194/jm-37-317-2018.

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Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.

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Carter, Samantha C., Elizabeth M. Griffith, Peter D. Clift, Howie D. Scher, and Timothy M. Dellapenna. "Clay-fraction strontium and neodymium isotopes in the Indus Fan: implications for sediment transport and provenance." Geological Magazine 157, no. 6 (May 13, 2020): 879–94. http://dx.doi.org/10.1017/s0016756820000394.

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AbstractReconstructing the provenance of siliciclastic marine sediment is important for understanding sediment pathways and constraining palaeoclimate and erosion records. However, physical fractionation of different size fractions can occur during sediment transport, potentially biasing records derived from bulk sediment. In this study, records of radiogenic Sr and Nd isotopic composition and K/Al ratio of the separated clay fraction, as well as bulk grain size, are presented, measured from deep-sea sediments recovered from International Ocean Discovery Program (IODP) Sites U1456 and U1457 in the Arabian Sea. These new records are compared with published bulk sediment records to investigate the influence of sediment transport on these proxies and to constrain provenance evolution and its relationship to climate variability since middle Miocene time. Correlations between grain size and the bulk sediment isotopic composition confirm that transport processes are influencing the bulk sediment record. This relationship, although present, is not as strong in the clay-fraction isotopic records. Heterogeneity of bulk sediment likely drives differences between bulk and clay records, thought to be largely controlled by sediment transport processes. The isotopic records reveal variations in provenance that correlate with climatic change at 8–7 Ma, as well as an increase in overall provenance variability beginning at c. 3.5 Ma, likely linked to monsoon strength and glacial–interglacial cycles. The clay-fraction records highlight the potential value of measuring proxy records from multiple size fractions to help constrain provenance records as well as investigate sediment transport and/or weathering and erosion processes recorded in deep-sea sediment archives.

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Voelker, A. H. L., T. Rodrigues, K. Billups, D. Oppo, J. McManus, R. Stein, J. Hefter, and J. O. Grimalt. "Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation." Climate of the Past 6, no. 4 (August 27, 2010): 531–52. http://dx.doi.org/10.5194/cp-6-531-2010.

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Abstract. Stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699) are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9–14 (300–540 ka). Core MD03-2699 is the first high-resolution mid-Brunhes record from the North Atlantic's eastern boundary upwelling system covering the complete MIS 11c interval and MIS 13. The array of sites reflect western and eastern basin boundary current as well as north to south transect sampling of subpolar and transitional water masses and allow the reconstruction of transport pathways in the upper limb of the North Atlantic's circulation. Hydrographic conditions in the surface and deep ocean during peak interglacial MIS 9 and 11 were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of which is slightly warmer. Enhanced subsurface northward heat transport in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktic foraminifer species and raises the question how strongly it impacted the Portuguese upwelling system. Deep water ventilation at the onset of MIS 11c significantly preceded surface water ventilation. Although MIS 13 was generally colder and more variable than the younger interglacials the surface water circulation scheme was the same. The greatest differences between the sites existed during the glacial inceptions and glacials. Then a north – south trending hydrographic front separated the nearshore and offshore waters off Portugal. While offshore waters originated from the North Atlantic Current as indicated by the similarities between the records of IODP Site U1313, ODP Site 980 and MD01-2446, nearshore waters as recorded in core MD03-2699 derived from the Azores Current and thus the subtropical gyre. Except for MIS 12, Azores Current influence seems to be related to eastern boundary system dynamics and not to changes in the Atlantic overturning circulation.

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Caissie, Beth E., Julie Brigham-Grette, Mea S. Cook, and Elena Colmenero-Hidalgo. "Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345)." Climate of the Past 12, no. 9 (September 1, 2016): 1739–63. http://dx.doi.org/10.5194/cp-12-1739-2016.

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Abstract. Records of past warm periods are essential for understanding interglacial climate system dynamics. Marine Isotope Stage 11 occurred from 425 to 394 ka, when global ice volume was the lowest, sea level was the highest, and terrestrial temperatures were the warmest of the last 500 kyr. Because of its extreme character, this interval has been considered an analog for the next century of climate change. The Bering Sea is ideally situated to record how opening or closing of the Pacific–Arctic Ocean gateway (Bering Strait) impacted primary productivity, sea ice, and sediment transport in the past; however, little is known about this region prior to 125 ka. IODP Expedition 323 to the Bering Sea offered the unparalleled opportunity to look in detail at time periods older than had been previously retrieved using gravity and piston cores. Here we present a multi-proxy record for Marine Isotope Stages 12 to 10 from Site U1345, located near the continental shelf-slope break. MIS 11 is bracketed by highly productive laminated intervals that may have been triggered by flooding of the Beringian shelf. Although sea ice is reduced during the early MIS 11 laminations, it remains present at the site throughout both glacials and MIS 11. High summer insolation is associated with higher productivity but colder sea surface temperatures, which implies that productivity was likely driven by increased upwelling. Multiple examples of Pacific–Atlantic teleconnections are presented including laminations deposited at the end of MIS 11 in synchrony with millennial-scale expansions in sea ice in the Bering Sea and stadial events seen in the North Atlantic. When global eustatic sea level was at its peak, a series of anomalous conditions are seen at U1345. We examine whether this is evidence for a reversal of Bering Strait throughflow, an advance of Beringian tidewater glaciers, or a turbidite.

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Hsieh, J. C., S. C. Huang, W. L. Chen, Y. C. Lai, and M. F. Tam. "Cysteine-86 is not needed for the enzymic activity of glutathione S-transferase 3-3." Biochemical Journal 278, no. 1 (August 15, 1991): 293–97. http://dx.doi.org/10.1042/bj2780293.

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Recombinant glutathione S-transferase 3-3 expressed in Spodoptera frugiperda (SF9) cells with the use of a baculovirus expression system was modified with 1 mM-iodoacetamide. Amino acid analysis indicated that 0.79 +/- 0.15 cysteine residue was modified per enzyme subunit. The S-carbaminomethylated protein retains the GSH-conjugating activity. Glutathione S-transferase 3-3 modified with iodo[14C]acetamide was digested with Achromobacter proteinase I and the resulting peptides were separated by h.p.l.c. The modified peptides were pooled and further digested with Staphylococcus aureus V8 proteinase. Isotope-labelled peptides were isolated and collected for N-terminal sequence analysis. By this procedure, cysteine-86 was identified as the major S-carbaminomethylated residue. Verification of this findings came from the use of site-directed mutagenesis in which this cysteine was replaced by serine (C86S mutant). The C86S mutant is enzymically active. Therefore cysteine-86 is not needed for the conjugation of GSH with electrophilic compounds on glutathione S-transferase 3-3.

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Blanchet, Cecile. "Deep-water formation in the Bering Sea? Insights from Nd isotopes for core U1341 (Bowers Ridge, IODP 323)." Quaternary International 279-280 (November 2012): 54. http://dx.doi.org/10.1016/j.quaint.2012.07.236.

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Hu, Ling-Zhi, Jin-Ting Kang, Yu-Han Qi, Yong-Jun Gao, Xiao-Yun Nan, Jian Huang, and Fang Huang. "Calcium isotope systematics of altered oceanic crust at IODP site 1256: Insights into the hydrothermal alteration." Lithos 438-439 (February 2023): 106994. http://dx.doi.org/10.1016/j.lithos.2022.106994.

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Kaboth, Stefanie, Patrick Grunert, and Lucas Lourens. "Mediterranean Outflow Water variability during the Early Pleistocene." Climate of the Past 13, no. 8 (August 17, 2017): 1023–35. http://dx.doi.org/10.5194/cp-13-1023-2017.

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Abstract. Gaining insights into the evolution of Mediterranean Outflow Water (MOW) during the Early Pleistocene has been so far hampered by the lack of available palaeoclimatic archives. Here we present the first benthic foraminifera stable oxygen and carbon isotope records and grain-size data from IODP Expedition 339 Site U1389 presently located within the upper core of the MOW in the Gulf of Cadiz for the time interval between 2.6 and 1.8 Ma. A comparison with an intermediate water mass record from the Mediterranean Sea strongly suggest an active MOW supplying Site U1389 on glacial–interglacial timescales during the Early Pleistocene. We also find indication that the increasing presence of MOW in the Gulf of Cadiz during the investigated time interval aligns with the progressive northward protrusion of Mediterranean sourced intermediate water masses into the North Atlantic, possibly modulating the intensification of the North Atlantic Meridional Overturning Circulation at the same time. Additionally, our results suggest that MOW flow strength was already governed by precession and semi-precession cyclicity during the Early Pleistocene against the background of glacial–interglacial variability.

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Westerhold, T., U. Röhl, H. Pälike, R. Wilkens, P. A. Wilson, and G. Acton. "Orbitally tuned timescale and astronomical forcing in the middle Eocene to early Oligocene." Climate of the Past 10, no. 3 (May 16, 2014): 955–73. http://dx.doi.org/10.5194/cp-10-955-2014.

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Abstract. Deciphering the driving mechanisms of Earth system processes, including the climate dynamics expressed as paleoceanographic events, requires a complete, continuous, and high-resolution stratigraphy that is very accurately dated. In this study, a robust astronomically calibrated age model was constructed for the middle Eocene to early Oligocene interval (31–43 Ma) in order to permit more detailed study of the exceptional climatic events that occurred during this time, including the middle Eocene climate optimum and the Eocene–Oligocene transition. A goal of this effort is to accurately date the middle Eocene to early Oligocene composite section cored during the Pacific Equatorial Age Transect (PEAT, IODP Exp. 320/321). The stratigraphic framework for the new timescale is based on the identification of the stable long eccentricity cycle in published and new high-resolution records encompassing bulk and benthic stable isotope, calibrated XRF core scanning, and magnetostratigraphic data from ODP Sites 171B-1052, 189-1172, 199-1218, and 207-1260 as well as IODP Sites 320-U1333, and 320-U1334 spanning magnetic polarity Chrons C12n to C20n. Subsequently orbital tuning of the records to the La2011 orbital solution was conducted. The resulting new timescale revises and refines the existing orbitally tuned age model and the geomagnetic polarity timescale from 31 to 43 Ma. The newly defined absolute age for the Eocene–Oligocene boundary validates the astronomical tuned age of 33.89 Ma identified at the Massignano, Italy, global stratotype section and point. The compilation of geochemical records of climate-controlled variability in sedimentation through the middle-to-late Eocene and early Oligocene demonstrates strong power in the eccentricity band that is readily tuned to the latest astronomical solution. Obliquity driven cyclicity is only apparent during 2.4 myr eccentricity cycle minima around 35.5, 38.3, and 40.1 Ma.

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Westerhold, T., U. Röhl, H. Pälike, R. Wilkens, P. A. Wilson, and G. Acton. "Orbitally tuned time scale and astronomical forcing in the middle Eocene to early Oligocene." Climate of the Past Discussions 9, no. 6 (December 18, 2013): 6635–82. http://dx.doi.org/10.5194/cpd-9-6635-2013.

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Abstract. Deciphering the driving mechanisms of Earth system processes, including the climate dynamics expressed as paleoceanographic events, requires a complete, continuous, and high-resolution stratigraphy that is very accurately dated. In this study, we construct a robust astronomically calibrated age model for the middle Eocene to early Oligocene interval (31–43 Ma) in order to permit more detailed study of the exceptional climatic events that occurred during this time, including the Middle Eocene Climate Optimum and the Eocene/Oligocene transition. A goal of this effort is to accurately date the middle Eocene to early Oligocene composite section cored during the Pacific Equatorial Age Transect (PEAT, IODP Exp. 320/321). The stratigraphic framework for the new time scale is based on the identification of the stable long eccentricity cycle in published and new high-resolution records encompassing bulk and benthic stable isotope, calibrated XRF core scanning, and magnetostratigraphic data from ODP Sites 171B-1052, 189-1172, 199-1218, and 207-1260 as well as IODP Sites 320-U1333, and -U1334 spanning magnetic polarity Chrons C12n to C20n. Subsequently we applied orbital tuning of the records to the La2011 orbital solution. The resulting new time scale revises and refines the existing orbitally tuned age model and the Geomagnetic Polarity Time Scale from 31 to 43 Ma. Our newly defined absolute age for the Eocene/Oligocene boundary validates the astronomical tuned age of 33.89 Ma identified at the Massignano (Italy) global stratotype section and point. Our compilation of geochemical records of climate-controlled variability in sedimentation through the middle-to-late Eocene and early Oligocene demonstrates strong power in the eccentricity band that is readily tuned to the latest astronomical solution. Obliquity driven cyclicity is only apparent during very long eccentricity cycle minima around 35.5, 38.3 and 40.1 Ma.

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Eriksson, Ludvig, Vladimir Tolmachev, and Stefan Sjöberg. "Feasibility of palladium-catalyzed isotopic exchange between sodium [125I]I and 2-iodo-para-carborane." Journal of Labelled Compounds and Radiopharmaceuticals 46, no. 7 (April 22, 2003): 623–31. http://dx.doi.org/10.1002/jlcr.702.

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Guo, Zhi Yong, Qiu Min Zhai, Tian Cai Dou, and Sai Sai Qin. "Early Pleistocene Variability of SST Record by Foraminifera Shell Mg/Ca Ratio at IODP Site U1313,North Atlantic." Advanced Materials Research 468-471 (February 2012): 1339–43. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.1339.

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In this paper, we measured Mg/Ca ratio in planktonic foraminifera shell of Globigerinoides ruber (white) from early Pleistocene (2414.2~2253.77ka) North Atlantic deep sea sediment drilled at Site U1313, IODP Expedition 306, and tested 6 transform functions that used to reconstruct sea surface temperature (SST) with foraminifera shell Mg/Ca ratio, the result showed that the theoretical equation of Elderfield and Ganssen (2000) and the equation of Anand (2003) both are appropriate, but there is big difference between their results, so we use their average value as the final results to reflect SST in the North Atlantic area in early Pleistocene. The fluctuation of the SST we reconstructed and that of the benthic foraminifera oxygen isotopic are basically same, but in the stages of MIS 87 to 95, there exist 2.71ka to 19.54ka error, probably it was caused by the difference of the response to changes in water temperature between the planktonic foraminifera and the benthic foraminifera.

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Pant, Naresh C., Francisco J. Jimenez-Espejo, Cary P. Cook, Paromita Biswas, Robert Mckay, Claudio Marchesi, Motoo Ito, et al. "Suspected meteorite fragments in marine sediments from East Antarctica." Antarctic Science 30, no. 5 (October 2018): 307–21. http://dx.doi.org/10.1017/s0954102018000299.

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AbstractUnusual mafic rock fragments deposited in Plio-Pleistocene-aged marine sediments were recorded at Integrated Ocean Drilling Program (IODP) Site U1359, in Wilkes Land, East Antarctica. These fragments were identified from sediment layers deposited between c. 3 and 1.2 Ma, indicating a sustained supply during this time interval. Clinopyroxenes in these basalts are Al–Ti diopside–hedenbergite, uncommon in terrestrial magmatic rocks. A single strong peak in the Raman spectra of a phosphate-bearing mineral at 963 cm-1 supports the presence of merrillite. Although not conclusive, petrological traits and oxygen isotopic compositions also suggest that the fragments may be extra-terrestrial fragments affected by shock metamorphism. Nevertheless, it is concluded that the basaltic fragments incorporated in marine sediments at Site U1359 represent ice-rafted material supplied to the continental rise of East Antarctica, probably from the bedrocks near the proximal Ninnis Glacier. Further studies on Plio-Pleistocene sediments near Site U1359 are required to characterize the unusual mafic rocks described.

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Toledo, Rodrigo, and Camilo Jimenez. "Recent advances in the management of malignant pheochromocytoma and paraganglioma: focus on tyrosine kinase and hypoxia-inducible factor inhibitors." F1000Research 7 (July 30, 2018): 1148. http://dx.doi.org/10.12688/f1000research.13995.1.

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Inactivating mutations of the succinate dehydrogenase subunit B (SDHB) gene and the subsequent stabilization and activation of the hypoxia-inducible factor 2-alpha (HIF2α) unit are recognized hallmarks associated with the development of metastatic pheochromocytomas and paragangliomas (MPPG). Despite this discovery, the development of systemic therapies for patients with MPPG has been very slow. The rarity of the disease, the lack of preclinical animal models, and the impracticable development of large clinical trials has hindered the therapeutic progress for MPPG. Chemotherapy and low-specific activity 131meta-iodo-benzyl-guanidine (MIBG) (manufactured by simple isotope exchange methodology) led to positive clinical responses in about a third of patients. Molecular targeted therapies were introduced into oncological clinical practice at the beginning of the 21st century. These therapies have been demonstrated to be effective for patients with cancers that previously exhibited limited responses to systemic chemotherapy, such as kidney and thyroid carcinomas and pancreatic neuroendocrine tumors. The pathogenesis of MPPG overlaps in some way with the pathogenesis of kidney, medullary thyroid, and pancreatic neuroendocrine carcinomas, providing scientific support to explore molecular targeted therapies such as tyrosine kinase and HIF inhibitors.

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Duke, Grace, Josie Frazer, Briar Taylor-Silva, and Christina Riesselman. "Two new clavate Fragilariopsis and one new Rouxia diatom species with biostratigraphic and paleoenvironmental applications for the Pliocene-Pleistocene, East Antarctica." Journal of Micropalaeontology 43, no. 1 (June 12, 2024): 139–63. http://dx.doi.org/10.5194/jm-43-139-2024.

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Abstract. Three new pennate diatom taxa, Fragilariopsis clava sp. nov. Duke; Fragilariopsis armandae sp. nov. Frazer, Duke et Riesselman; and Rouxia raggattensis sp. nov. Duke et Riesselman, are described and named from Pliocene-Pleistocene sediments collected from the continental rise adjacent to the Wilkes Land coast of East Antarctica. The stratigraphic occurrence of F. clava and F. armandae at IODP Site U1361 are well-constrained to Marine Isotope Stages G9-G7 (2.76–2.74 Ma) and 101–97 (2.58–2.47 Ma), respectively. The short stratigraphic ranges of F. clava and F. armandae are potentially useful biostratigraphic markers for constraining the age of late Pliocene to Early Pleistocene Antarctic sediments. Rouxia raggattensis is observed in the oldest sample examined at Site U1361 from ∼4.05 Ma and is more common between 3.0–2.15 Ma. The rise in abundance of R. raggattensis corresponds to a large turnover in diatom species between 3 and 2 Ma associated with Antarctic cooling, suggesting that sea surface conditions were favorable for R. raggattensis during this dynamic time. Clavate Fragilariopsis species diversified between 2.9–2.7 Ma, but some species quickly went extinct between 2.7–2.5 Ma, possibly because they were marginalized by the cooler climate conditions.

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Huang, Jian, Sheng-Ao Liu, Yongjun Gao, Yilin Xiao, and Sha Chen. "Copper and zinc isotope systematics of altered oceanic crust at IODP Site 1256 in the eastern equatorial Pacific." Journal of Geophysical Research: Solid Earth 121, no. 10 (October 2016): 7086–100. http://dx.doi.org/10.1002/2016jb013095.

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Manthey, M., and W. Preetz. "Schwingungsspektren und Normalkoordinatenanalyse der 35Cl/37Cl-isotopierten Chloro-Iodo-Osmate(IV), [OsClnI6-n]2-, n = 0-6 / Vibrational Spectra and Normal Coordinate Analysis of the 35Cl/37Cl Labelled Chloro-Iodo-Osmates(IV), [OsClnI6-n]2-, n = 0-6." Zeitschrift für Naturforschung B 48, no. 6 (June 1, 1993): 747–53. http://dx.doi.org/10.1515/znb-1993-0608.

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All components of the two series [Os35ClnI6-n]2- and [Os37ClnI6-n]2-, n = 0-6, including the pairs of geometric isomers for n = 2, 3, 4, have been prepared and isolated by ion exchange chromatography on DEAE cellulose. The highly resolved low temperature (80 K) IR and Raman spectra of the pure isotopomers show distinct isotopic shifts for different vibrational modes up to 10 cm-1. Normal coordinate analyses have been performed, based on a general valence force field. Due to the stronger trans influence of I as compared to Cl in all asymmetric Cl˙—Os—I′ axes the Os—I′ bonds are strengthened and the Os—Cl˙ bonds are weakened, as indicated by valence force constants for Os—I′ approximately 9% higher, for Os—Cl˙ 7% lower, as compared with the values calculated for symmetric axes.

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Middleton, Jennifer L., Julia Gottschalk, Gisela Winckler, Jean Hanley, Carol Knudson, Jesse R. Farmer, Frank Lamy, and Lorraine E. Lisiecki. "Evaluating manual versus automated benthic foraminiferal δ¹⁸O alignment techniques for developing chronostratigraphies in marine sediment records." Geochronology 6, no. 2 (April 17, 2024): 125–45. http://dx.doi.org/10.5194/gchron-6-125-2024.

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Abstract. Paleoceanographic interpretations of Plio-Pleistocene climate variability over the past 5 million years rely on the evaluation of event timing of proxy changes in sparse records across multiple ocean basins. In turn, orbital-scale chronostratigraphic controls for these records are often built from stratigraphic alignment of benthic foraminiferal stable oxygen isotope (δ18O) records to a preferred dated target stack or composite. This chronostratigraphic age model approach yields age model uncertainties associated with alignment method, target selection, the assumption that the undated record and target experienced synchronous changes in benthic foraminiferal δ18O values, and the assumption that any possible stratigraphic discontinuities within the undated record have been appropriately identified. However, these age model uncertainties and their impact on paleoceanographic interpretations are seldom reported or discussed. Here, we investigate and discuss these uncertainties for conventional manual and automated tuning techniques based on benthic foraminiferal δ18O records and evaluate their impact on sedimentary age models over the past 3.5 Myr using three sedimentary benthic foraminiferal δ18O records as case studies. In one case study, we present a new benthic foraminiferal δ18O record for International Ocean Discovery Program (IODP) Site U1541 (54°13′ S, 125°25′ W), recently recovered from the South Pacific on IODP Expedition 383. The other two case studies examine published benthic foraminiferal δ18O records of Ocean Drilling Program (ODP) Site 1090 and the ODP Site 980/981 composite. Our analysis suggests average age uncertainties of 3 to 5 kyr associated with manually derived versus automated alignment, 1 to 3 kyr associated with automated probabilistic alignment itself, and 2 to 6 kyr associated with the choice of tuning target. Age uncertainties are higher near stratigraphic segment ends and where local benthic foraminiferal δ18O stratigraphy differs from the tuning target. We conclude with recommendations for community best practices for the development and characterization of age uncertainty of sediment core chronostratigraphies based on benthic foraminiferal δ18O records.

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Voelker, Antje. "Variability during Marine Isotope Stages 11, 13 and 15 as revealed at IODP Sites U1313 and U1305 (North Atlantic)." Quaternary International 279-280 (November 2012): 523. http://dx.doi.org/10.1016/j.quaint.2012.08.1816.

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Beddow, Helen M., Diederik Liebrand, Appy Sluijs, Bridget S. Wade, and Lucas J. Lourens. "Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)." Paleoceanography 31, no. 1 (January 2016): 81–97. http://dx.doi.org/10.1002/2015pa002820.

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Courtillat, Margot, Maximilian Hallenberger, Maria-Angela Bassetti, Dominique Aubert, Catherine Jeandel, Lars Reuning, Chelsea Korpanty, Pierre Moissette, Stéphanie Mounic, and Mariem Saavedra-Pellitero. "New Record of Dust Input and Provenance During Glacial Periods in Western Australia Shelf (IODP Expedition 356, Site U1461) from the Middle to Late Pleistocene." Atmosphere 11, no. 11 (November 20, 2020): 1251. http://dx.doi.org/10.3390/atmos11111251.

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International Ocean Discovery Program (IODP) Expedition 356 Site U1461 represents one of the few records from the North West Australian shelf that provides information about aridity fluctuations in Australia during the Quaternary. A combination of chronostratigraphic indicators revealed the (partial) preservation of two major glaciations (Marine Isotope Stage (MIS) 2 and MIS 12) in the sedimentary record. The faunal content (mainly benthic foraminifera, corals and bryozoans) was analyzed to estimate paleo-environments and paleo-depths in order to determine if these sediments have been remobilized by reworking processes. Despite the occurrence of a depositional hiatus (including MIS 5d to MIS 9-time interval), the excellent preservation of faunal content suggests that the preserved sediment is in situ. The geochemical composition of the sediments (Nd and major elements) indicates that during MIS 12 riverine input was likely reduced because of enhanced aridity, and the sediment provenance (mainly atmospheric dust) is likely in the central (Lake Eyre) or eastern (Murray Darling Basin) parts of the Australian continent. MIS 2 is confirmed to be one of the driest periods recorded in Australia but with mixed dust sources from the eastern and western parts of the continent. More humid conditions followed the glacial maximum, which might correspond to the peak of the Indian-Australian Summer Monsoon.

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Khim, Boo-Keun, Keiji Horikawa, Yoshihiro Asahara, Ji-Eun Kim, and Minoru Ikehara. "Detrital Sr–Nd isotopes, sediment provenances and depositional processes in the Laxmi Basin of the Arabian Sea during the last 800 ka." Geological Magazine 157, no. 6 (November 23, 2018): 895–907. http://dx.doi.org/10.1017/s0016756818000596.

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Abstract87Sr/86Sr ratios and εNd values of detrital particles at International Ocean Discovery Program (IODP) Site U1456 in the Laxmi Basin of the Arabian Sea were measured to trace changes in sediment provenance over glacial–interglacial cycles. Based on the correlation of planktonic foraminiferal (Globigerinoides ruber) δ18O fluctuations with the LR04 stack of benthic foraminifera δ18O values, combined with shipboard biostratigraphic and palaeomagnetic data, the studied interval spans ∼1.2 Ma. Over the past 800 ka, 87Sr/86Sr values ranged from 0.711 to 0.726 while εNd values ranged between −12.5 and −7.3 in the detrital particles. By comparing 87Sr/86Sr ratios and εNd values of the possible sources of river sediments with our data, we found that sediments in the Laxmi Basin were influenced to various degrees by proportions of at least three sediment sources (i.e. Tapi River, Narmada River and Indus River). The Indus River might be a more important contributor to glacial sediments. Although 87Sr/86Sr ratios and εNd values varied quasi-cyclically, this pattern did not correspond precisely to the glacial–interglacial cycles. In particular, low-magnetic-susceptibility (low-MS) intervals coinciding with pelagic carbonates were characterized by low 87Sr/86Sr ratios and high εNd values, whereas high-MS intervals matching turbidite deposits showed high 87Sr/86Sr ratios and low εNd values. Thus, this study reveals that differences in the depositional processes between glacial and interglacial periods, governed by changes in sea level and monsoon activity, are an important factor in deciding 87Sr/86Sr ratios and εNd values of the detrital fraction in the Indus Fan of the Arabian Sea.

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Yamaguchi, Tatsuhiko, Kentaro Kuroki, Katsura Yamada, Takuya Itaki, Kaoru Niino, and Isao Motoyama. "Pleistocene deep-sea ostracods from the Oki Ridge, Sea of Japan (IODP Site U1426) and condition of the intermediate water." Quaternary Research 88, no. 3 (September 22, 2017): 430–45. http://dx.doi.org/10.1017/qua.2017.68.

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AbstractThe Sea of Japan (also termed the East Sea) has a circulation system isolated from the Pacific Ocean and East China Sea. The East Asian winter monsoon drives the circulation system and cools the Tsushima Warm Current (TWC) to form the Japan Sea Intermediate–Proper Water (JSIPW). The intermediate water conveys oxygen to deep-sea floors, which is available for benthic animals. During the Pliocene (3.5–2.8 Ma), Temperate Intermediate Water (TIW) was formed under the weak winter monsoon, and extinct ostracod TIW taxa were found. Little is known about early Pleistocene intermediate water and the extinction mode of benthic ostracods. We studied radiolarians and ostracods from deep-sea sediments between 2.0 and 1.3 Ma (Marine Oxygen Isotope Stage [MIS] 77 to MIS 41) at Integrated Ocean Drilling Program Site U1426, Sea of Japan. The ostracod faunas contained TIW and JSIPW taxa. The radiolarian subtropical-water taxa and the JSIPW ostracods indicate a small influx of the TWC and the JSIPW. The TIW occasionally expanded to the middle bathyal zone. By analogy with the relationship between the modern JSIPW and winter monsoon, weak winter monsoon possibly caused gentle temperature gradients in the water column and the expansion of the TIW. The JSIPW taxa expanded their ranges into the deep sea during interglacial periods.

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Suzuki, Kenta, Masanobu Yamamoto, and Osamu Seki. "Late Miocene changes in C3, C4 and aquatic plant vegetation in the Indus River basin: evidence from leaf wax δ13C from Indus Fan sediments." Geological Magazine 157, no. 6 (October 28, 2019): 979–88. http://dx.doi.org/10.1017/s0016756819001109.

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AbstractVegetation changes in the Indus River basin within the past 10.8 million years were investigated based on the analysis of n-fatty acids and their carbon isotopes in sediments from IODP Site U1457 in the Laxmi Basin of the Arabian Sea. The δ13C of long-chain n-C32 fatty acid shifted from −34 to −22 ‰ from 10 to 6.3 Ma, while the δ13C of mid-chain n-C24 fatty acid was nearly constant at around −23 to −22 ‰ over the same period. This large difference in the δ13C values suggests that the mid-chain fatty acids reflect the contribution of aquatic vascular C3 plants. Before 6.3 Ma, the average chain length of n-fatty acids and the δ13C values of long-chain fatty acids were negatively correlated, suggesting that the δ13C values reflected the relative abundance of terrestrial C3 versus aquatic C3 plants in the Indus River basin and western India. After 5.8 Ma, the average chain length was variable, but the δ13C values remained nearly the same, suggesting that the δ13C values reflected heavier δ13C values of both aquatic C3 and C4 plants. A three-end-member model calculation suggests that terrestrial C3 plants were replaced by C4 plants in the Indus River basin and western India from 9.7 or 8.2 to 6.3 Ma. Aridification in those areas during the late Miocene period may have driven the replacement of terrestrial C3 plants by C4 plants. An episodic increase in the abundance of terrestrial plants around 8 Ma is attributed to elevated precipitation by regionally enhanced moisture transport.

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Szücs, Dániel, Judit P. Szabó, Viktória Arató, Barbara Gyuricza, Dezső Szikra, Imre Tóth, Zita Képes, György Trencsényi, and Anikó Fekete. "Investigation of the Effect on the Albumin Binding Moiety for the Pharmacokinetic Properties of 68Ga-, 205/206Bi-, and 177Lu-Labeled NAPamide-Based Radiopharmaceuticals." Pharmaceuticals 16, no. 9 (September 11, 2023): 1280. http://dx.doi.org/10.3390/ph16091280.

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Although radiolabeled alpha-melanocyte stimulating hormone-analogue NAPamide derivatives are valuable melanoma-specific diagnostic probes, their rapid elimination kinetics and high renal uptake may preclude them from being used in clinical settings. We aimed at improving the pharmacokinetics of radiolabeled DOTA-NAPamide compounds by incorporating a 4-(p-iodo-phenyl)-butanoic acid (IPB) into the molecules. Followed by 68Ga-, 205/206Bi-, and 177Lu-labelling, the radiopharmaceuticals ([68Ga]Ga-DOTA-IPB-NAPamide, [205/206Bi]Bi-DOTA-IPB-NAPamide, [177Lu]Lu-DOTA-IPB-NAPamide) were characterized in vitro. To test the imaging behavior of the IPB-containing probes, B16F10 tumor-bearing C57BL/6 mice were subjected to in vivo microPET/microSPECT/CT imaging and ex vivo biodistribution studies. All tracers were stable in vitro, with radiochemical purity exceeding 98%. The use of albumin-binding moiety lengthened the in vivo biological half-life of the IPB-carrying radiopharmaceuticals, resulting in elevated tumor accumulation. Both [68Ga]Ga-DOTA-IPB-NAPamide (5.06 ± 1.08 %ID/g) and [205/206Bi]Bi-DOTA-IPB-NAPamide (4.50 ± 0.98 %ID/g) exhibited higher B16F10 tumor concentrations than their matches without the albumin-binding residue ([68Ga]Ga-DOTA-NAPamide and [205/206Bi]Bi-DOTA-NAPamide: 1.18 ± 0.27 %ID/g and 3.14 ± 0.32; respectively), however; the large amounts of off-target radioactivity do not confirm the benefits of half-life extension for short-lived isotopes. Enhanced [177Lu]Lu-DOTA-IPB-NAPamide tumor uptake even 24 h post-injection proved the advantage of IPB-based prolonged circulation time regarding long-lived radionuclides, although the significant background noise must be addressed in this case as well.

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Xuan, Chuang, James E. T. Channell, and David A. Hodell. "Quaternary magnetic and oxygen isotope stratigraphy in diatom-rich sediments of the southern Gardar Drift (IODP Site U1304, North Atlantic)." Quaternary Science Reviews 142 (June 2016): 74–89. http://dx.doi.org/10.1016/j.quascirev.2016.04.010.

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Huang, Jian, Shan Ke, Yongjun Gao, Yilin Xiao, and Shuguang Li. "Magnesium isotopic compositions of altered oceanic basalts and gabbros from IODP site 1256 at the East Pacific Rise." Lithos 231 (August 2015): 53–61. http://dx.doi.org/10.1016/j.lithos.2015.06.009.

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Shchukin, E., A. Orlova, M. Korsakov, S. Sjöberg, and V. Tolmachev. "Copper-mediated isotopic exchange between [125I]iodide and bis(triethylammonium) undecahydro-12-iodo-closo-dodecaborate in aqueous media." Journal of Radioanalytical and Nuclear Chemistry 260, no. 2 (2004): 295–99. http://dx.doi.org/10.1023/b:jrnc.0000027099.63853.cc.

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LI, Q., J. WANG, J. CHEN, and Q. WEI. "STABLE CARBON ISOTOPES OF BENTHIC FORAMINIFERS FROM IODP EXPEDITION 311 AS POSSIBLE INDICATORS OF EPISODIC METHANE SEEP EVENTS IN A GAS HYDRATE GEOSYSTEM." PALAIOS 25, no. 10 (October 1, 2010): 671–81. http://dx.doi.org/10.2110/palo.2010.p10-011r.

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Lim, Dhongil, Zhaokai Xu, Jihun Kim, Wei Wang, Emma Ownsworth, David Selby, Runsheng Yin, and Taesoo Chang. "Enhanced volcanic activity and long-term warmth in the middle Eocene revealed by mercury and osmium isotopes from IODP Expedition 369 Site U1514." Earth and Planetary Science Letters 627 (February 2024): 118565. http://dx.doi.org/10.1016/j.epsl.2023.118565.

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Channell, J. E. T., J. D. Wright, A. Mazaud, and J. S. Stoner. "Age through tandem correlation of Quaternary relative paleointensity (RPI) and oxygen isotope data at IODP Site U1306 (Eirik Drift, SW Greenland)." Quaternary Science Reviews 88 (March 2014): 135–46. http://dx.doi.org/10.1016/j.quascirev.2014.01.022.

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Lee, Jongmin, Sunghan Kim, Jae Il Lee, Hyen Goo Cho, Stephen C. Phillips, and Boo-Keun Khim. "Monsoon-influenced variation of clay mineral compositions and detrital Nd-Sr isotopes in the western Andaman Sea (IODP Site U1447) since the late Miocene." Palaeogeography, Palaeoclimatology, Palaeoecology 538 (January 2020): 109339. http://dx.doi.org/10.1016/j.palaeo.2019.109339.

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Dang, Haowen, Nana Peng, and Zhimin Jian. "A dataset of the Plio-Pleistocene at IODP Site U1489: Benthic foraminifera stable carbon and oxygen isotopes, coarse fraction, and selected benthic foraminifera abundances." Data in Brief 28 (February 2020): 105020. http://dx.doi.org/10.1016/j.dib.2019.105020.

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Journal articles on the topic 'Iode – Isotopes'

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