@article {thatcher_iberian_2022, title = {Iberian hydroclimate variability and the Azores High during the last 1200 years: evidence from proxy records and climate model simulations}, journal = {Climate Dynamics}, year = {2022}, month = {08/2022}, pages = {1{\textendash}23}, abstract = {The state of the atmospheric circulation and the associated hydroclimate in the North Atlantic during the last millennium remain the subject of considerable debate in both proxy- and model-based studies. Of particular interest in the Iberian region is the Azores High (AH) system, the southern node of the North Atlantic Oscillation (NAO), an atmospheric dipole closely tied to regional hydroclimate. Hydroclimate-sensitive proxy reconstructions from this region offer some insights into atmospheric dynamics, but large spatiotemporal gaps in these data inhibit a robust evaluation of hydroclimate variability. In this study, we present a continuous, sub-decadally-resolved composite stalagmite carbon isotopic record from three partially overlapping stalagmites from Buraca Gloriosa (BG) cave, western Portugal, situated within the center of the AH, that preserves evidence of regional hydroclimate variability from approximately 800 CE to the present. Chronologies are derived from U/Th dating and annual laminae. Stalagmite carbon isotopic values primarily reflect the amount of effective moisture and reveal generally dry conditions during the Medieval Climate Anomaly (MCA; 850{\textendash}1250 CE) and Modern Climate/Industrial Era (1850 CE-present), and wetter conditions during the Little Ice Age (LIA; 1400{\textendash}1850 CE). Multidecadal to centennial variability in the BG record and state-of-the-art last millennium climate model simulations show considerable coherence with precipitation-sensitive records from Spain and Morocco that, like BG, are strongly influenced by the intensity, size, and location of the AH. Model-proxy synthesis suggests that western Portugal was persistently dry during much of the MCA consistent with other NAO reconstructions; however, even considering age uncertainties, the apparent timing in the transition from a relatively dry MCA to a wetter LIA is spatially variable and confirms the non-stationary behavior of the AH system indicated by model output.}, keywords = {Azores High, Hydroclimate, last millennium, Last Millennium Ensemble, Paleoclimate, Stalagmite}, doi = {10.1007/s00382-022-06427-6}, url = {https://app.dimensions.ai/details/publication/pub.1150271437}, author = {Thatcher, Diana L. and Wanamaker, A. D. and Denniston, R. F. and Ummenhofer, C. C. and Asmerom, Y. and Polyak, V. J. and Cresswell-Clay, N. and Hasiuk, F. and Haws, J. and Gillikin, D. P.} } @article {bennett_evidence_2021, title = {Evidence of humans in North America during the Last Glacial Maximum}, journal = {Science}, volume = {373}, number = {6562}, year = {2021}, note = {Publisher: American Association for the Advancement of Science}, month = {09/2021}, pages = {1528{\textendash}1531}, abstract = {Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. Questions remain about when and how people migrated, where they originated, and how their arrival affected the established fauna and landscape. Here, we present evidence from excavated surfaces in White Sands National Park (New Mexico, United States), where multiple in situ human footprints are stratigraphically constrained and bracketed by seed layers that yield calibrated radiocarbon ages between \textasciitilde23 and 21 thousand years ago. These findings confirm the presence of humans in North America during the Last Glacial Maximum, adding evidence to the antiquity of human colonization of the Americas and providing a temporal range extension for the coexistence of early inhabitants and Pleistocene megafauna.}, doi = {10.1126/science.abg7586}, url = {https://www.science.org/doi/full/10.1126/science.abg7586}, author = {Bennett, Matthew R. and Bustos, David and Pigati, Jeffrey S. and Springer, Kathleen B. and Urban, Thomas M. and Holliday, Vance T. and Reynolds, Sally C. and Budka, Marcin and Honke, Jeffrey S. and Hudson, Adam M. and Fenerty, Brendan and Connelly, Clare and Martinez, Patrick J. and Santucci, Vincent L. and Odess, Daniel} } @article {2673, title = {Two-Phase Synthesis of Taxol}, journal = {Journal of the American Chemical Society}, volume = {142}, year = {2020}, month = {Oct-06-2020}, pages = {10526 - 10533}, abstract = {Taxol (a brand name for paclitaxel) is widely regarded as among the most famed natural isolates ever discovered, and has been the subject of innumerable studies in both basic and applied science. Its documented success as an anticancer agent, coupled with early concerns over supply, stimulated a furious worldwide effort from chemists to provide a solution for its preparation through total synthesis. Those pioneering studies proved the feasibility of retrosynthetically guided access to synthetic Taxol, albeit in minute quantities and with enormous effort. In practice, all medicinal chemistry efforts and eventual commercialization have relied upon natural (plant material) or biosynthetically derived (synthetic biology) supplies. Here we show how a complementary divergent synthetic approach that is holistically patterned off of biosynthetic machinery for terpene synthesis can be used to arrive at Taxol.}, keywords = {1ST TOTAL-SYNTHESIS, ANALOGS, chemistry, DIMETHYLDIOXIRANE, ENANTIOSELECTIVE TOTAL-SYNTHESIS, FORMAL TOTAL-SYNTHESIS, PINENE PATH, RING, STEREOCONTROLLED SYNTHESIS, TAXANES}, issn = {0002-7863}, doi = {10.1021/jacs.0c0359210.1021/jacs.0c03592.s00110.1021/jacs.0c03592.s002}, url = {https://pubs.acs.org/doi/10.1021/jacs.0c03592}, author = {Kanda, Yuzuru and Nakamura, Hugh and Umemiya, Shigenobu and Puthukanoori, Ravi Kumar and Murthy Appala, Venkata Ramana and Gaddamanugu, Gopi Krishna and Paraselli, Bheema Rao and Baran, Phil S.} } @conference {2821, title = {Evaluating Playas as Point Sources for Recharge of the High Plains Aquifer, Western Kansas}, booktitle = {Joint 53rd Annual South-Central/53rd North-Central/71st Rocky Mtn GSA Section Meeting - 2019}, year = {2019}, publisher = {Geological Society of America}, organization = {Geological Society of America}, doi = {10.1130/abs/2019SC-327385}, url = {https://www.researchgate.net/publication/333623353_EVALUATING_PLAYAS_AS_SOURCES_OF_RECHARGE_TO_THE_HIGH_PLAINS_AQUIFER_IN_WESTERN_KANSAS}, author = {Stotler, Randy L. and Salley, Kaitlin A. and Johnson, William C. and Ryuh, Yon-Gyung} } @article {2701, title = {Pacific climate influences on ocean conditions and extreme shell growth events in the Northwestern Atlantic (Gulf of Maine)}, journal = {Climate Dynamics}, volume = {52}, year = {2019}, month = {Jan-06-2019}, pages = {6339 - 6356}, abstract = {The Gulf of Maine is undergoing rapid environmental and ecological changes, yet our spatial and temporal understanding of the climatic and hydrographic variability in this region, including extreme events, is limited and biased to recent decades. In this study, we utilize a highly replicated, multi-century master shell growth chronology derived from the annual increments formed in the shells of the long-lived bivalve Arctica islandica collected in 38 m from the central coastal region in the Gulf of Maine. Our results indicate that shell growth is highly synchronous and inversely related to local seawater temperatures. Using composite analyses of extreme shell growth events from CE 1900 to 2013, we extend our understanding of the factors driving oceanic variability and shell growth in the Northwestern Atlantic back to CE 1761. We suggest that extreme shell growth events are primarily controlled by Gulf of Maine sea surface temperature (SST) and stratification conditions, which in turn appear to be largely influenced by SST patterns in the Pacific Ocean through their influence on mid-latitude atmospheric circulation patterns and the location of the eddy-driven jet. The large-scale jet dynamics during these extreme years manifest as precipitation and moisture transport anomalies and regional SST conditions in the Gulf of Maine that either enhance or inhibit shell growth. Pacific climate variability is thus an important, yet understudied, influence on Gulf of Maine ocean conditions.}, issn = {0930-7575}, doi = {10.1007/s00382-018-4513-8}, url = {https://link.springer.com/article/10.1007/s00382-018-4513-8}, author = {Wanamaker, Alan D. and Griffin, Shelly M. and Ummenhofer, Caroline C. and Whitney, Nina M. and Black, Bryan and Parfitt, Rhys and Lower-Spies, Erin E. and Introne, Douglas and Kreutz, Karl J.} } @article {2692, title = {Organic Carbon Aging During Across-Shelf Transport}, journal = {Geophysical Research Letters}, volume = {45}, year = {2018}, month = {Apr-08-2020}, pages = {8425 - 8434}, abstract = {Compound-specific radiocarbon analysis (CSRA) was performed on different grain-size fractions of surficial sediments to examine and compare lateral transport times (LTTs) of organic carbon. 14C aging of long-chain leaf wax fatty acids along two dispersal pathways of fluvially-derived material on adjacent continental margins implies LTTs over distances of ~30 to 500 km that range from hundreds to thousands of years. The magnitude of aging differs among grain size fractions. Our finding suggests that LTTs vary both temporally and spatially as a function of the specific properties of different continental shelf settings. Observations suggest that 14C aging is widespread during lateral transport over continental shelves, with hydrodynamic particle sorting inducing age variations among organic components residing in different grain sizes. Consideration of these phenomena is of importance for understanding carbon cycle processes and interpretation on sedimentary records on continental margins.}, issn = {0094-8276}, doi = {10.1029/2018GL078904}, url = {https://core.ac.uk/download/pdf/222887698.pdf}, author = {Bao, Rui and Uchida, Masao and Zhao, Meixun and Haghipour, Negar and Montlucon, Daniel and McNichol, Ann and Wacker, Lukas and Hayes, John M. and Eglinton, Timothy I.} } @article {2714, title = {Vegetation responses to late Holocene climate changes in an Andean forest}, journal = {Quaternary Research}, volume = {89}, year = {2018}, month = {Jan-01-2018}, pages = {60 - 74}, abstract = {A paleoecological record from Lake Palotoa (1370 m elevation) in the Andean foothills of Peru spans the last 3800 years. Lake Palotoa lies near the modern cloud base in a location sensitive to changes in atmospheric moisture. In many areas, these forests have been destroyed, but Lake Palotoa shows no sign of human occupation today or in the past. The modern forest surrounding the lake is dominated by the Andean palm, Dictyocaryum lamarckianum, which is also the most abundant taxon in the fossil pollen record. Fossil pollen data show the vegetation assemblages have not experienced strong compositional changes in the late Holocene. Global-scale climatic events such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) are identified within the record, though the vegetation responses are subtle. Hedyosmum and Sloanea pollen percentages increase near the onset of the MCA and may reflect decreased seasonality. The LIA coincides with increased Hedyosmum pollen percentages, and increases in Clethra and Begonia, two elements that tend to occupy forests now found at higher elevations. Our findings demonstrate the stability of montane forest systems to natural Holocene climate change.}, keywords = {Cloud forest, Dictyocaryum, Fossil pollen, Little ice age, Medieval Climate Anomaly, seasonality, Tropical ecology}, issn = {0033-5894}, doi = {10.1017/qua.2017.64}, url = {https://www.cambridge.org/core/product/identifier/S0033589417000643/type/journal_article}, author = {Schiferl, Jacob D. and Bush, Mark B. and Silman, Miles R. and Urrego, Dunia H.} } @article {2856, title = {Holocene sea ice variability driven by wind and polynya efficiency in the Ross Sea}, journal = {Nature Communications}, volume = {8}, year = {2017}, month = {Jan-12-2017}, abstract = {The causes of the recent increase in Antarctic sea ice extent, characterised by large regional contrasts and decadal variations, remain unclear. In the Ross Sea, where such a sea ice increase is reported, 50\% of the sea ice is produced within wind-sustained latent-heat polynyas. Combining information from marine diatom records and sea salt sodium and water isotope ice core records, we here document contrasting patterns in sea ice variations between coastal and open sea areas in Western Ross Sea over the current interglacial period. Since about 3600 years before present, an increase in the efficiency of regional latent-heat polynyas resulted in more coastal sea ice, while sea ice extent decreased overall. These past changes coincide with remarkable optima or minima in the abundances of penguins, silverfish and seal remains, confirming the high sensitivity of marine ecosystems to environmental and especially coastal sea ice conditions.}, doi = {10.1038/s41467-017-01455-x}, url = {http://www.nature.com/articles/s41467-017-01455-x}, author = {Mezgec, K. and Stenni, B. and Crosta, X. and Masson-Delmotte, V. and Baroni, C. and Braida, M. and Ciardini, V. and Colizza, E. and Melis, R. and Salvatore, M. C. and Severi, M. and Scarchilli, C. and Traversi, R. and Udisti, R. and Frezzotti, M.} } @article {2598, title = {Paleohydrology of China Lake basin and the context of early human occupation in the northwestern Mojave Desert, USA}, journal = {Quaternary Science Reviews}, volume = {167}, year = {2017}, month = {Jan-07-2017}, pages = {112 - 139}, abstract = {Considerable prior research has focused on the interconnected pluvial basins of Owens Lake and Searles Lake, resulting in a long record of paleohydrological change in the lower Owens River system. However, the published record is poorly resolved or contradictory for the period encompassing the terminal Pleistocene (22,000 to 11,600 cal BP) and early Holocene (11,600-8200 cal BP). This has resulted in conflicting interpretations about the timing of lacustrine high stands within the intermediate basin of China Lake, which harbors one of the most extensive records of early human occupation in the western Great Basin and California. Here, we report a broad range of radiocarbon-dated paleoenvironmental evidence, including lacustrine deposits and shoreline features, tufa outcrops, and mollusk, ostracode, and fish bone assemblages, as well as spring and other groundwater-related deposits (a.k.a. "black mats") from throughout China Lake basin, its outlet, and inflow drainages. Based on 98 radiocarbon dates, we develop independent evidence for five significant lake-level oscillations between 18,000 and 13,000 cal BP, and document the persistence of groundwater-fed wetlands from the beginning of the Younger Dryas through the early Holocene (12,900-8200 cal BP); including the transition from ground-water fed lake to freshwater marsh between about 13,000 and 12,600 cal BP. Results of this study support and refine existing evidence that shows rapid, high-amplitude oscillations in the water balance of the Owens River system during the terminal Pleistocene, and suggest widespread human use of China Lake basin began during the Younger Dryas.}, issn = {02773791}, doi = {10.1016/j.quascirev.2017.04.023}, url = {http://linkinghub.elsevier.com/retrieve/pii/S027737911630676Xhttp://api.elsevier.com/content/article/PII:S027737911630676X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S027737911630676X?httpAccept=text/plain}, author = {Rosenthal, Jeffrey S. and Meyer, Jack and Palacios-Fest, Manuel R. and Young, D. Craig and Ugan, Andrew and Byrd, Brian F. and Gobalet, Ken and Giacomo, Jason} } @article {2539, title = {Age of the Mt.~Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum}, journal = {The Cryosphere}, volume = {10}, year = {2016}, month = {Jan-01-2016}, pages = {2779 - 2797}, abstract = {In 2011 four ice cores were extracted from the summit of Alto dell{\textquoteright}Ortles (3859 m), the highest glacier of South Tyrol in the Italian Alps. This drilling site is located only 37 km southwest from where the Tyrolean Iceman, \~{}5.3 kyrs old, was discovered emerging from the ablating ice field of Tisenjoch (3210 m, near the Italian{\textendash}Austrian border) in 1991. The excellent preservation of this mummy suggested that the Tyrolean Iceman was continuously embedded in prehistoric ice and that additional ancient ice was likely preserved elsewhere in South Tyrol. Dating of the ice cores from Alto dell{\textquoteright}Ortles based on 210Pb, tritium, beta activity and 14C determinations, combined with an empirical model (COPRA), provides evidence for a chronologically ordered ice stratigraphy from the modern glacier surface down to the bottom ice layers with an age of \~{}7 kyrs, which confirms the hypothesis. Our results indicate that the drilling site has continuously been glaciated on frozen bedrock since \~{}7 kyrs BP. Absence of older ice on the highest glacier of South Tyrol is consistent with the removal of basal ice from bedrock during the Northern Hemisphere Climatic Optimum (6{\textendash}9 kyrs BP), the warmest interval in the European Alps during the Holocene. Borehole inclinometric measurements of the current glacier flow combined with surface ground penetration radar (GPR) measurements indicate that, due to the sustained atmospheric warming since the 1980s, an acceleration of the glacier Alto dell{\textquoteright}Ortles flow has just recently begun. Given the stratigraphic chronological continuity of the Mt. Ortles cores over millennia, it can be argued that this behaviour has been unprecedented at this location since the Northern Hemisphere Climatic Optimum.}, doi = {10.5194/tc-10-2779-2016}, url = {http://www.the-cryosphere.net/10/2779/2016/tc-10-2779-2016.pdf}, author = {Gabrielli, Paolo and Barbante, Carlo and Bertagna, Giuliano and {\'o}, Michele and Binder, Daniel and Carton, Alberto and Carturan, Luca and Cazorzi, Federico and Cozzi, Giulio and Dalla Fontana, Giancarlo and Davis, Mary and De Blasi, Fabrizio and Dinale, Roberto and {\`a}, Gianfranco and Dreossi, Giuliano and Festi, Daniela and Frezzotti, Massimo and Gabrieli, Jacopo and Galos, Stephan P. and Ginot, Patrick and Heidenwolf, Petra and Jenk, Theo M. and Kehrwald, Natalie and Kenny, Donald and Magand, Olivier and Mair, Volkmar and Mikhalenko, Vladimir and Lin, Ping Nan and Oeggl, Klaus and Piffer, Gianni and Rinaldi, Mirko and Schotterer, Ulrich and Schwikowski, Margit and Seppi, Roberto and Spolaor, Andrea and Stenni, Barbara and Tonidandel, David and Uglietti, Chiara and Zagorodnov, Victor and Zanoner, Thomas and Zennaro, Piero} } @article {VanDaele2016130, title = {Late Quaternary evolution of Lago Castor (Chile, 45.6{\textdegree}S): Timing of the deglaciation in northern Patagonia and evolution of the southern westerlies during the last 17 kyr}, journal = {Quaternary Science Reviews}, volume = {133}, year = {2016}, pages = {130 - 146}, abstract = {Abstract Even though Patagonia is ideally located to study climate of the southern mid-latitudes, many questions on the late Quaternary climate evolution remain unresolved. The timing of maximum glacier extent is still uncertain in vast areas, and the postglacial evolution of the Southern Westerly Wind Belt (SWWB) remains highly debated. Here, we study the sedimentary infill of a glacigenic lake (Lago Castor; 45.6{\textdegree}S, 71.8{\textdegree}W) located at the leeside of the Andes in Chilean Patagonia to i) reconstruct the deglacial evolution of the eastern flank of the Patagonian Ice Sheet (PIS), and ii) discuss postglacial changes in wind strength at a critical location where westerly wind records are critically lacking. A dense grid of high-resolution reflection-seismic data was used to reconstruct the large-scale infill history of the lake, and a radiocarbon dated sediment core penetrating all lacustrine seismic units, was retrieved. Results indicate that the deglaciation of the lake basin and its catchment occurred no later than \~{}28~cal~kyr \{BP\} (i.e. an early LGM), but possibly even already after \{MIS\} 4. Afterwards, the Lago Castor area was covered by a large proglacial lake that drained {\textendash} possibly through an outburst flood {\textendash} when the \{PIS\} outlet glaciers retreated to a critical location. Subsequently, very dry conditions caused the lake to desiccate, as evidenced by an unconformity visible on the seismic profiles and in the sediment core. This dry period likely resulted from the increased orographic effect of the PIS-covered Andes, accompanied by weaker westerlies. From \~{}20~kyr \{BP\} onwards, the combination of a shrinking \{PIS\} and a southward shift of the \{SWWB\} resulted in increased precipitation, which caused the lake level to rise. After \~{}17~cal~kyr BP, lake sedimentation was more directly influenced by the southern westerlies, with the formation of sediment drifts resulting from strong bottom current during periods of intense westerly winds. Our results suggest a progressive increase in wind strength at 46{\textdegree}S from 11.2 to 4.5~cal~kyr BP, which supports the hypothesis that the \{SWWB\} broadened during the early and middle Holocene.}, keywords = {Sediment drift}, issn = {0277-3791}, doi = {http://doi.org/10.1016/j.quascirev.2015.12.021}, url = {http://www.sciencedirect.com/science/article/pii/S027737911530202X}, author = {Maarten Van Daele and S{\'e}bastien Bertrand and Inka Meyer and Jasper Moernaut and Willem Vandoorne and Giuseppe Siani and Niels Tanghe and Zakaria Ghazoui and Mario Pino and Roberto Urrutia and Marc De Batist} } @article {2586, title = {North Atlantic forcing of tropical Indian Ocean climate}, journal = {Nature}, volume = {509}, year = {2014}, month = {Jun-04-2016}, pages = {76 - 80}, abstract = {The response of the tropical climate in the Indian Ocean realm to abrupt climate change events in the North Atlantic Ocean is contentious. Repositioning of the intertropical convergence zone is thought to have been responsible for changes in tropical hydroclimate during North Atlantic cold spells1, 2, 3, 4, 5, but the dearth of high-resolution records outside the monsoon realm in the Indian Ocean precludes a full understanding of this remote relationship and its underlying mechanisms. Here we show that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean. Our results are based on new, high-resolution sea surface temperature and seawater oxygen isotope records of well-dated sedimentary archives from the tropical eastern Indian Ocean for the past 45,000 years, combined with climate model simulations of Atlantic circulation slowdown under Marine Isotope Stages 2 and 3 boundary conditions. Similar conditions in the east and west of the basin rule out a zonal dipole structure as the dominant forcing of the tropical Indian Ocean hydroclimate of millennial-scale events. Results from our simulations and proxy data suggest dry conditions in the northern Indian Ocean realm and wet and warm conditions in the southern realm during North Atlantic cold spells.}, keywords = {Palaeoceanography, Palaeoclimate}, issn = {0028-0836}, doi = {10.1038/nature13196}, url = {http://www.nature.com/doifinder/10.1038/nature13196}, author = {Mohtadi, Mahyar and Prange, Matthias and Oppo, Delia W. and De Pol-Holz, Ricardo and Merkel, Ute and Zhang, Xiao and Steinke, Stephan and {\"u}ckge, Andreas} } @article {117, title = {Changes in sub-fossil chironomid assemblages in two Northern Patagonian lake systems associated to the occurrence of historical fires}, journal = {Journal of Paleolimnology}, volume = {50}, year = {2013}, note = {id: 2121}, pages = {41-56}, abstract = {Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practically unpolluted waters. However, during the twentieth century the burning of natural forests was one of the most important human activities in Northern Chilean Patagonia. Some estimations indicate that three million hectares were burned during the first three decades of the century. Hence the objective of this study was to evaluate the impacts of the historical fires in Lake Burgos (45{\textordmasculine}42'S) and Lake Thompson (45{\textordmasculine}38'S) in Chilean Patagonia. The impact was measured by evaluating chironomid assemblage since they are sensitive enough to be used as an indicator of aquatic ecosystem health. Fires have a direct and drastic effect on a lake watershed but also indirectly affect a lake ecosystem, changing sedimentation patterns or increasing nutrient inputs. In the studied lakes the periods with higher prevalence of fires were identified by charcoal analysis, while organic matter and magnetic susceptibility allowed the confirmation of pre-fire and post-fire periods. The chironomid composition was evaluated through a PCA and an analysis of similarity (ANOSIM) to test the significance among periods while a Detrended Correspondence Analysis was applied to the chironomid assemblage downcore to assess compositional structure and taxa turnover. In Lake Burgos the ANOSIM test indicated significant differences between the pre-fire and fire periods (p}, doi = {10.1007/s10933-013-9703-0}, author = {Araneda, A. and Ortega, C. and Jana, P. and Torrejon, F. and Bertrand, S. and Vargas, P. and Fagel, N. and Alvarez, D. and Urrutia, R.} } @article {130, title = {Chemical and bacteriological analysis of soil from the Middle and Late Weichselian from Western Spitsbergen, Arctic}, journal = {The environment and chronology of the earliest occupation of north-west Europe: current knowledge, problems and new research directions}, volume = {271}, year = {2012}, note = {id: 2316}, pages = {98-105}, abstract = {This paper discusses temporal variability in the biogeochemical properties of the deeper permafrost soils of Western Spitsbergen, Arctic, that dates back up to the Middle Weichselian period (44.8 ka BP). Results indicate that during the mid of the last interstadial (\~{}37 ka BP) the chemical and biological properties of the soils were different from the stadial period that followed. Trace element concentration during the period remained low. Electrical conductivity along with K, Mg, Na, SO4-2, Cl- and HCO3- content of the soils during this period was high. Mineralizable nitrogen, organic carbon, biomass nitrogen and total bacterial counts were also high. These observations concurrently lead to a conclusion that the soils of Western Spitsbergen during the interstadial period were under marine influence. The culturability of bacterial cells was low which increased later with the onset of the stadial.}, issn = {1040-6182}, doi = {10.1016/j.quaint.2012.03.008}, url = {http://www.sciencedirect.com/science/article/pii/S1040618212001541}, author = {Singh, Shiv Mohan and Sharma, Jagdev and Gawas-Sakhalkar, Puja and Upadhyay, Ajay K. and Naik, Simantini and Bande, Dnyanesh and Ravindra, Rasik} } @article {126, title = {Climatic and environmental evolution of Lake Iznik (NW Turkey) over the last \~{}4700 years}, journal = {Temporal and spatial corridors of Homo sapiens sapiens population dynamics during the Late Pleistocene and Early Holocene}, volume = {274}, year = {2012}, note = {id: 2337}, pages = {88-101}, abstract = {Magnetic susceptibility, geochemistry, mineralogy and palynology of sediments from Lake Iznik in Northwestern Anatolia, Turkey, provide a 4700 year record of climatic trends and events. The measured proxies allow a reconstruction of variations in humid/dry periods and lake level changes. The Lake Iznik sedimentary sequence points to an oscillating trend of humid periods interrupted by rapid climate change (RCC) to arid periods. Especially abrupt lithologic and geochemical changes at 4.2 and 3.3 ka calBP may outline intense droughts, which extremely lowered the lake level. For the last 2000 years, the effects of the Roman warm period, Dark Age cold period, Medieval Warm Period and Little Ice Age are recorded within Lake Iznik sediments. Besides many similarities of local climatic periods with other records from the Eastern Mediterranean, there are also differences indicating the complex pattern of the climate in the region.}, issn = {1040-6182}, doi = {10.1016/j.quaint.2012.06.016}, url = {http://www.sciencedirect.com/science/article/pii/S1040618212004363}, author = {{\"U}lgen, Umut Bar{\i}{\c s} and Franz, Sven Oliver and Biltekin, Demet and {\c C}a{\u g}atay, M. Namik and Roeser, Patricia Angelika and Doner, Lisa and Thein, Jean} } @article {2561, title = {ENSO Drove 2500-Year Collapse of Eastern Pacific Coral Reefs}, journal = {Science}, volume = {337318333105323329353215234133898029327161272715118 119109123420422375802767219435149464823345354035608535771415}, year = {2012}, month = {Jun-07-2012}, pages = {81 - 84}, abstract = {Cores of coral reef frameworks along an upwelling gradient in Panam{\'a} show that reef ecosystems in the tropical eastern Pacific collapsed for 2500 years, representing as much as 40\% of their history, beginning about 4000 years ago. The principal cause of this millennial-scale hiatus in reef growth was increased variability of the El Ni{\~n}o{\textendash}Southern Oscillation (ENSO) and its coupling with the Intertropical Convergence Zone. The hiatus was a Pacific-wide phenomenon with an underlying climatology similar to probable scenarios for the next century. Global climate change is probably driving eastern Pacific reefs toward another regional collapse.}, issn = {0036-8075}, doi = {10.1126/science.1221168}, url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1221168}, author = {Toth, L. T. and Aronson, R. B. and Vollmer, S. V. and Hobbs, J. W. and Urrego, D. H. and Cheng, H. and Enochs, I. C. and Combosch, D. J. and van Woesik, R. and Macintyre, I. G.} } @article {2566, title = {Sea surface temperature variability and sea-ice extent in the subarctic northwest Pacific during the past 15,000 years}, journal = {Paleoceanography}, volume = {27}, year = {2012}, month = {Jan-09-2012}, pages = {n/a - n/a}, abstract = {Past changes in North Pacific sea surface temperatures and sea-ice conditions are proposed to play a crucial role in deglacial climate development and ocean circulation but are less well known than from the North Atlantic. Here, we present new alkenone-based sea surface temperature records from the subarctic northwest Pacific and its marginal seas (Bering Sea and Sea of Okhotsk) for the time interval of the last 15 kyr, indicating millennial-scale sea surface temperature fluctuations similar to short-term deglacial climate oscillations known from Greenland ice core records. Past changes in sea-ice distribution are derived from relative percentage of specific diatom groups and qualitative assessment of the IP25biomarker related to sea-ice diatoms. The deglacial variability in sea-ice extent matches the sea surface temperature fluctuations. These fluctuations suggest a linkage to deglacial variations in Atlantic meridional overturning circulation and a close atmospheric coupling between the North Pacific and North Atlantic. During the Holocene the subarctic North Pacific is marked by complex sea surface temperature trends, which do not support the hypothesis of a Holocene seesaw in temperature development between the North Atlantic and the North Pacific.}, doi = {10.1029/2012PA002292}, url = {http://doi.wiley.com/10.1029/2012PA002292}, author = {Max, Lars and Riethdorf, Jan-Rainer and Tiedemann, Ralf and Smirnova, Maria and Lembke-Jene, Lester and Fahl, Kirsten and {\"u}rnberg, Dirk and Matul, Alexander and Mollenhauer, Gesine} } @article {160, title = {Using the N/C ratio to correct bulk radiocarbon ages from lake sediments: Insights from Chilean Patagonia}, journal = {Quaternary Geochronology}, volume = {12}, year = {2012}, note = {id: 2296}, pages = {23-29}, abstract = {The offset between AMS radiocarbon ages obtained on bulk lake sediments and the true age of deposition was evaluated at four sites in Northern Chilean Patagonia. Our results show that the bulk radiocarbon ages are systematically older by 300 to 1100 years. In this region free of carbonate and carbonaceous rocks, we argue that this difference results from variable inputs of terrestrial organic carbon from the Holocene soils that cover the lake watersheds. For the four studied lakes, the age offset is clearly related to the fraction of terrestrial carbon preserved in the lake sediments, which was estimated using the N/C ratio of the bulk organic matter. We propose that N/C measurements can be used to significantly improve chronologies based on radiocarbon dating of bulk lake sediments.}, issn = {1871-1014}, doi = {10.1016/j.quageo.2012.06.003}, url = {http://www.sciencedirect.com/science/article/pii/S1871101412001112}, author = {Bertrand, S{\'e}bastien and Araneda, Alberto and Vargas, Patricia and Jana, Patricia and Fagel, Nathalie and Urrutia, Roberto} } @article {208, title = {East{\textendash}West similarities and differences in the surface and deep northern Arabian Sea records during the past 21 Kyr}, journal = {Palaeogeography, Palaeoclimatology, Palaeoecology}, volume = {301}, year = {2011}, note = {id: 2100}, pages = {75-85}, abstract = {This study analyses monsoon proxy Globigerina bulloides from Ocean Drilling Program (ODP) Hole 723A (western Arabian Sea) and Hole ABP-25, 02 (northeastern Arabian Sea) as well as dominant benthic foraminifera, pteropods, total organic carbon (TOC), Inorganic Carbon (IC) and stable isotope values of benthic foraminifera from Hole ABP-25, 02 to understand summer monsoon-driven changes in the western and eastern Arabian Sea and their impacts on deep-sea ventilation during the past 21 Kyr. We have also combined published TOC data from ODP Hole 724B to understand if deep-sea conditions in the Arabian Sea were same throughout the region during the studied interval. The summer monsoon was generally weaker during cold intervals including the Last Glacial Maximum, the Younger Dryas and the Bond events of the Holocene. From 20 to 10 Kyr, the deep northeastern Arabian Sea was better oxygenated with less organic carbon supply except during 14{\textendash}12.5 Kyr when TOC values increased, indicating a weaker summer monsoon and a weak oxygen minimum zone (OMZ). The TOC values and the abundance of the eutrophic benthic foraminiferal species Bulimina aculeata, Melonis barleeanum and Uvigerina peregrina increased during the late Holocene whereas well-oxygenated, low organic carbon benthic species Sphaeroidina bulloides as well as pteropods decreased, indicating an intense OMZ and an increased supply of refractory organic material to the Arabian Sea. It is important to note that although the surface response to monsoon variability was more or less similar in the western and northeastern Arabian Sea, the deep-sea conditions show a marked contrast in the two regions during the past 21 Kyr.}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2010.12.027}, url = {http://www.sciencedirect.com/science/article/pii/S0031018211000022}, author = {Gupta, Anil K. and Mohan, K. and Sarkar, Sudipta and Clemens, Steven C. and Ravindra, Rasik and Uttam, Rajesh K.} } @article {239, title = {From ice age to modern: a record of landscape change in an Andean cloud forest}, journal = {Journal of Biogeography}, volume = {37}, year = {2010}, note = {id: 869; 639ND Times Cited:5 Cited References Count:63Y}, pages = {1637-1647}, abstract = {Aim}, issn = {0305-0270}, doi = {10.1111/J.1365-2699.2010.02318.X}, author = {Valencia, B. G. and Urrego, D. H. and Silman, M. R. and Bush, M. B.} } @article {240, title = {A long history of cloud and forest migration from Lake Consuelo, Peru}, journal = {Quaternary Research}, volume = {73}, year = {2010}, note = {id: 1903; 564VS Times Cited:8 Cited References Count:85Y}, pages = {364-373}, abstract = {The complete paleoecological history from Lake Consuelo forest yields a record of ground-level cloud formation and changes in its lower altitudinal limit over the last 46,300 cal yr BP. The timing of early lake level fluctuations prior to 37,000 cal yr BP appears sensitive to North Atlantic temperature oscillations, corresponding to Dansgaard-Oeschger interstadials 11, 10 and 8 recorded in GISP2. After the LGM, the first hint of warming is recorded in Lake Consuelo at 22,000 call yr BP and agrees with other estimates for the region. The mid-Holocene (7400-5000 cal yr BP) was the period of highest rates of change and most significant reorganizations in the Consuelo forest. These community changes resulted from a regionally widespread dry period. Results from Lake Consuelo indicate that moisture availability, mediated through cloud cover, played the most significant role in ecological change in this system. Rates of past climate fluctuations never exceeded the forest capacity to accommodate change. Unfortunately, this might not be the case under predicted scenarios for the end of the current century. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.}, issn = {0033-5894}, doi = {10.1016/J.Yqres.2009.10.005}, author = {Urrego, D. H. and Bush, M. B. and Silman, M. R.} } @inbook {1449, title = {Submarine Mass Transport Within Monterey Canyon: Benthic Disturbance Controls on the Distribution of Chemosynthetic Biological Communities}, booktitle = {Submarine mass movements and their consequences, 4th International Symposium:}, year = {2010}, note = {id: 879}, month = {2010}, pages = {229-246}, publisher = {Springer}, organization = {Springer}, abstract = {Documenting mass transport within Monterey Canyon and Fan has been a focus of remotely operated vehicle (ROV) observations, sampling, monitoring, and multibeam mapping studies. These efforts indicate that major mass transport events occur within upper Monterey Canyon (2 km water depths) and onto Monterey Fan for ~100 years. Simultaneous efforts to document the distribution of benthic taxa observed in the video records from 668 ROV dives conducted by the Monterey Bay Aquarium Research Institute (MBARI) provide a uniquely detailed record of the occurrence of chemosynthetic biological communities (CBC). The combined results of these studies provide an understanding of the relationship between disturbance caused by episodic mass wasting events and the distribution of CBC. CBC are common within the canyon{\textquoteright}s axis below ~2.5 km water depth, but have not been found within the canyon{\textquoteright}s axis at depths shallower than 2 km. Moreover, CBC occur on the canyon walls at essentially any depth, primarily within young (~hundreds of years old) slump scars. The distribution of CBC provides evidence about the disturbance history of the seafloor. Major mass transport events will destroy communities that lie in their path. Erosion associated with major mass transport events can create environments to support CBC by exposing methane-bearing strata. This can happen as a result of slumping events on the sidewalls of the canyon or where major gravity flow events have excavated the base of canyon walls. Once fresh strata are exposed, geochemical conditions to support CBC will persist for a few centuries. Because CBC are composed of slow-growing and long-lived organisms, it will take decades for these communities to be established. Their existence indicates that environmental stability has occurred over a similar time scale.}, author = {Paull, C. K. and Schlining, B. and Ussler, W. and Lundste, E. and Barry, J. P. and Caress, D. W. and Johnson, J. E. and McGann, M.}, editor = {Mosher, D. C.} } @article {2446, title = {Method for determining coal carbon in the reclaimed minesoils contaminated with coal}, journal = {Soil Science Society of America Journal}, volume = {72}, year = {2008}, note = {24}, month = {Jan-Feb}, pages = {231-237}, abstract = {Minesoils are anthropic soils developed on land disturbed by mining activities. Minesoils developed on the reclaimed surface-mined sites for coal are contaminated with coal particles resulting from mining and reclamation activities. Therefore, the total organic carbon (TOC) pool in these sites is a mixture of coal and plant-derived recent soil organic carbon (SOC). Accurate estimates of SOC pools and C sequestration rates in the reclaimed minesoils (RMS) is limited by the lack of a standard and cost-effective method for determination of coal C concentrations in the RMS. The chemi-thermal method, based on the oxidative resistance of coal, was developed and validated with radiocarbon analysis using selected artificial soil-coal mixtures and minesoil samples. Radiocarbon analysis of RMS samples indicated that minesoils from the top 10-cm depth developing from topsoil applied during reclamation was coal C free. The contribution of coal C and the radiocarbon age of TOC increased with increasing soil depth. The coal C fraction accounted for 0 to 92\% of TOC in the RMS samples. The coal C fraction was highly correlated with delta C-13 (r(2) = 0.84), suggesting that stable isotope composition could estimate the coal C concentration in RMS samples. Analysis of coal and artificial soil and coal mixtures indicated that chemi-thermal treatment was effective in removing recent SOC with minimum effect on coal. Analysis of RMS samples indicated that both radiocarbon activity and the chemi-thermal method were effective in estimating coal C concentration in RMS of southeast Ohio. The coal C concentrations for both methods were highly correlated (r(2) = 0.95), suggesting that the chemi-thermal method was as effective as radiocarbon activity measurement in estimating coal C concentration in these soils.}, keywords = {BLACK CARBON, C-14, FOREST, GENESIS, MATTER, MINING DISTRICT, RICH MINE SOILS, sediments, SITES, SOIL ORGANIC-CARBON}, isbn = {0361-5995}, doi = {10.1016/j.dsr2.2008.07.005}, author = {Ussiri, D. A. N. and Lai, R.} } @article {2004, title = {Catastrophic meltwater discharge down the Hudson River Valley: A potential trigger for the Intra-Allerod cold period}, journal = {Geology}, volume = {33}, year = {2005}, note = {id: 1033}, month = {2005}, pages = {89-92}, author = {Donnelly, J. P. and Driscoll, N. and Uchupi, E. and Keigwin, L. and Schwab, W. and Thieler, E. R. and Swift, S.} } @article {1976, title = {Foraminiferal isotope anomalies from northwestern Pacific marginal sediments}, journal = {Geochemistry Geophysics Geosystems}, volume = {6}, year = {2005}, note = {917qmTimes Cited:9 Cited References Count:48 }, month = {Apr 12}, pages = {1525-2027}, abstract = {[1] We evaluated the influence of methane release from methane hydrate reservoirs in the northwestern Pacific continental margin on stable isotope values. We analyzed stable isotopes of foraminifera from a piston core collected at 1066-m water depth off eastern Hokkaido, northern Japan. Carbon isotope signals indicated that planktonic and benthic foraminifera in several glacial sediment layers in the core were highly depleted in C-13; both the planktonic and benthic foraminiferal delta C-13 values ranged from about -10 parts per thousand to -2 parts per thousand. Most foraminiferal tests in these horizons were brown as a result of postdepositional alteration. Foraminiferal oxygen isotopes fluctuated abnormally in the glacial sediment layers, showing small ( about 0.5 parts per thousand) positive shifts relative to normal glacial values. We attributed the positive shifts to authigenic carbonate formation in the foraminiferal tests. The authigenic carbonates have formed when rising methane, from methane hydrate in the sediment, became oxidized as it came in contact with dissolved sulfate near the seafloor. Episodic methane-release events may be associated with great plate-boundary earthquakes with epicenters near the coring site.}, keywords = {atmospheric processes : paleoclimatology, benthic foraminifera, California, carbon isotopes, corals, Foraminifera, gas-hydrate, kuril trench, marine geology and geophysics : marine sediments : processes and transport, methane hydrate, methane release, northwestern pacific ocean, sea-level record, tokachi-oki earthquake, western north pacific, Younger Dryas}, isbn = {1525-2027}, doi = {10.1029/2004GC000787}, url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&SrcAuth=Alerting\&SrcApp=Alerting\&DestApp=WOS\&DestLinkType=FullRecord;UT=WOS:000228479400002}, author = {Ohkushi, K. and Ahagon, N. and Uchida, M. and Shibata, Y.} } @article {1963, title = {The last glacial maximum: stability and change in an Andean cloud forest}, journal = {Journal of Quaternary Science}, volume = {20}, year = {2005}, note = {id: 458}, month = {2005}, pages = {693-701}, author = {Urrego, D. H. and Silman, M. R. and Bush, M. B.} } @article {978, title = {48,000 years of climate and forest change from a biodiversity hotspot}, journal = {Science}, volume = {303}, year = {2004}, note = {id: 1016}, pages = {827-829}, abstract = {A continuous 48,000-year-long paleoecological record from Neotropical lower montane forest reveals a consistent forest presence and an ice-age cooling of \~{}5{\textdegree} to 9{\textdegree}C. After 30,000 years of compositional stability, a steady turnover of species marks the 8000-year-long transition from ice-age to Holocene conditions. Although the changes were directional, the rates of community change were no different during this transitional period than in the preceding 30,000-year period of community stability. The warming rate of about 1{\textdegree}C per millennium during the Pleistocene-Holocene transition was an order of magnitude less than the projected changes for the 21st century.}, doi = {10.1126/science.1090795 }, author = {Bush, M. B. and Silman, M. R. and Urrego, D. H.} } @article {909, title = {AMS 14C measurement and preparative techniques at NIES-TERRA}, journal = {Nuclear Instruments and Methods in Physics Research B}, volume = {223-224}, year = {2004}, note = {id: 1492}, pages = {116-123}, abstract = {The AMS facility at the National Institute for Environmental Studies (NIES) has now been operating for five years since 1997. This AMS-dedicated facility named NIES-TERRA (Tandem accelerator for Environmental Research and Radiocarbon Analysis) consists of a 5MV tandem Pelletron (15SDH-2), a solid ion source with sequential injection system, a gas ion source with a simultaneous injection system, and a gas ionization detector. Typical precision with 14C measurements is around 0.5\% and the background level has been achieved at around 50 kBP. Our main target is radiocarbon in environmental sciences, while other cosmogenic isotopes (10Be and 26Al) have been measured. Recently we have improved our preparation laboratory to increase sample throughput. CO2 production and purification using a commercial elemental analyzer connected to cryogenic traps (EA{\textendash}CT) were investigated. We used a modified elemental analyzer with a chemical trap for separation and this is expected to reduce memory effect and background in comparison with an analyzer using gas-chromatography. This newly designed EA{\textendash}CT system showed high precision and accuracy. Source of background contamination was also discussed based on the analysis of various amounts of standard materials.}, doi = {10.1016/j.nimb.2004.04.026}, author = {Yoneda, Minoru and Shibata, Yasuyuki and Tanaka, Atsushi and Uehiro, Takashi and Morita, Masatoshi and Uchida, Masao and Kobayashi, Toshiyuki and Kobayashi, Chiaki and Suzuki, Ryo and Miyamoto, Keisuke and Hancock, Boze and Dibden, Chris and Edmonds, John S.} } @article {2015, title = {Episodic methane release events from Last Glacial marginal sediments in the western North Pacific}, journal = {Geochemistry Geophysics Geosystems}, volume = {5}, year = {2004}, note = {849mvTimes Cited:13 Cited References Count:73 }, month = {Aug 19}, pages = {1525-2027}, abstract = {[1] According to recent observations of anomalous bottom-simulating reflections (BSR),the northwest Pacific marginal sediments around Japan main islands bear large abundances of methane hydrate [Satoh, 2002]. During the Last Glacial, direct and indirect evidence accumulated from geochemical data suggests that methane episodically released from hydrate trapped in the seafloor sediments [ Dickens et al., 1995; Hinrichs et al., 2003; Kennett et al., 2000]. Here we show that marginal sediments from the western North Pacific contain a hopanoid 17alpha( H), 21beta(H)-hop-22(29)-ene ( diploptene) derived from the activity of methanotrophic bacteria in water column and/or surface sediment during a warming period (Interstadial 3) in the Last Glacial. The carbon isotopic compositions of diploptene range between - 41.0parts per thousand and - 27.9parts per thousand ( relative to PDB). In the horizon indicative of a contribution of methanotrophic bacteria, foraminiferal isotope signals were also found with highly depleted C-13 compositions of planktonic foraminifera ( similar to - 1.9parts per thousand, PDB) and benthic foraminifera ( similar to - 0.8parts per thousand, PDB), suggesting indirect records of enhanced incorporation of C-13-depleted CO2 formed by methanotrophic process that use C-12-enriched methane as their main source of carbon. From combined isotopic data of molecular ( diploptene) and foraminifera, the most prominent signal of methane release was detected in the sediments deposited around 25.4 cal. kyr BP ( similar to 100 year time span), corresponding to the Interstadial 3. This is the first evidence of methane hydrate instability in the open western North Pacific during the Last Glacial. Considering the glacial-interglacial hydrographic conditions in this region, the instability of methane hydrate may be modulated by intermediate water warming and/or the lowering of sea level. Our results suggest that the western North Pacific marginal regions may be a profound effect on rapid global warming climate changes during the Last Glacial.}, keywords = {atmospheric composition and structure : geochemical cycles, atmospheric methane, carbon isotopes, carbon isotopic fractionation, climate-change, cold seeps, diploptene, Foraminifera, gas-hydrate, geochemistry : isotopic composition/chemistry, geochemistry : organic geochemistry, hydrocarbons, interglacial, intermediate water, methane hydrate, santa-barbara basin, sea sediments, subduction zone, western north pacific}, isbn = {1525-2027}, doi = {10.1029/2004GC000699}, url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&SrcAuth=Alerting\&SrcApp=Alerting\&DestApp=WOS\&DestLinkType=FullRecord;UT=WOS:000223543700001}, author = {Uchida, M. and Shibata, Y. and Ohkushi, K. and Ahagon, N. and Hoshiba, M.} } @article {568, title = {Glacial intermediate water ventilation in the northwestern Pacific based on AMS radiocarbon dating}, journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms}, volume = {223}, year = {2004}, note = {852jtTimes Cited:7Cited References Count:13}, month = {Aug}, pages = {460-465}, abstract = {C-14 ages of benthic foraminifera and planktonic foraminifera in sediment core PC4 (41degrees07.10{\textquoteright}N, 142degrees24.17{\textquoteright}E) collected from the northwestern Pacific were measured by accelerator mass spectrometry. The purpose of this study was to investigate the changes in intermediate water ventilation in the northwestern Pacific during the last glacial period. We used age differences between benthic foraminifera and planktonic foraminifera from the same sediment horizons to estimate the ventilation time of intermediate water. Planktonic C-14 ages show that the core recorded paleoenvironmental changes during the last 35 kyr. Glacial benthic-planktonic age differences were smaller in the early deglacial period (15000-17000 cal yr BP) than in the period (19000-30000 cal yr BP) before and during the last glacial maximum. The results at intermediate depths are consistent with those from a Pacific deep-water site. (C) 2004 Elsevier B.V. All rights reserved.}, issn = {0168-583x}, doi = {10.1016/j.nimb.2004.04.087}, author = {Ohkushi, K. and Uchida, M. and Ahagon, N. and Mishima, T. and Kanematsu, T.} } @article {276, title = {Mid-depth circulation in the northwest Pacific during the last deglaciation: Evidence from foraminiferal radiocarbon ages}, journal = {Geophysical Research Letters}, volume = {30}, year = {2003}, note = {id: 405; 742FU Times Cited:19 Cited References Count:23}, pages = {2-1 - 2-4}, abstract = {Sediment cores (MR01-K03 PC4/PC5, 1366 m water depth) collected from off northern Japan were studied using coexisting planktonic and benthic foraminiferal radiocarbon measurements to reconstruct the history of mid-depth circulation in the northwest Pacific. Reconstructed ventilation ages indicate that, consistent with data from a previous radiocarbon study at a shallower site, there was significant variation in mid-depth circulation during the last deglaciation, especially in the Bolling-Allerod (13-15 ka) and Younger Dryas (11.5-13 ka) intervals. Our record indicates that the ventilation changes in the North Pacific were antiphase to those of the North Atlantic, suggesting that atmospheric moisture transport associated with the Asian Monsoon might have played a great role in millennium-scale ventilation changes in the North Pacific during the last deglaciation.}, issn = {0094-8276}, doi = {10.1029/2003gl018287}, author = {Ahagon, N. and Ohkushi, K. and Uchida, M. and Mishima, T.} } @article {1479, title = {Blackwood Creek Strem restoration project design draft report}, year = {2002}, note = {id: 1140}, month = {2002}, address = {South Lake, Tahoe, CA}, author = {Beck, N. and Hydrology, S.}, editor = {Unit, U. S. Forest Service Lake Tahoe Basin Management} } @article {692, title = {Comparative analysis of methane-oxidizing archaea and sulfate-reducing bacteria in anoxic marine sediments}, journal = {Appl Environ Microbiol}, volume = {67}, year = {2001}, note = {Orphan, V JHinrichs, K UUssler, W 3rdPaull, C KTaylor, L TSylva, S PHayes, J MDelong, E FengComparative StudyResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.2001/04/03 10:00Appl Environ Microbiol. 2001 Apr;67(4):1922-34.}, month = {Apr}, pages = {1922-34}, abstract = {The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the order Methanosarcinales, were consistently associated with methane seep marine sediments. The same sediments contained abundant (13)C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia. (13)C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of delta-proteobacteria, in particular, close relatives of Desulfosarcina variabilis. Biomarker analyses of the same sediments showed bacterial fatty acids with strong (13)C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing Desulfosarcina and Desulfococcus species. Additionally, the presence of abundant (13)C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the order Desulfosarcinales, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although the Desulfosarcinales and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.}, issn = {0099-2240 (Linking)}, doi = {10.1128/AEM.67.4.1922-1934.2001}, author = {Orphan, V. J. and Hinrichs, K. U. and Ussler, W. and Paull, C. K. and Taylor, L. T. and Sylva, S. P. and Hayes, J. M. and DeLong, E. F.} } @article {821, title = {Drainage of late Wisconsin glacial lakes and the morphology and late quaternary stratigraphy of the New Jersey-southern New England continental shelf and slope}, journal = {Marine Geology}, volume = {172}, year = {2001}, note = {400trTimes Cited:50Cited References Count:115}, month = {Jan 15}, pages = {117-145}, abstract = {We propose that late Wisconsin deposition and erosion (Hudson Shelf and Block Island valleys) on the shelf and slope from New Jersey to southern New England were a consequence of the catastrophic drainage of glacial lakes behind terminal moraine systems and the huge volume of water stored beneath the Laurentian ice sheet and subsequent erosion of the lake sediments by flash floods. The morphology imparted by glaciation regulated the discharge associated with the ablation of the glaciers. Associated with the deposits west of Hudson Shelf Valley are the remains of mammoth and mastodon which were transported from their living habitats along the lake shores to their present burial sites on the shelf. The floods also triggered gravity flows on the upper continental slope which made possible the transportation of coarse debris over hundreds of km into the deep-sea. That these catastrophic hood morphologies can still be recognized on the middle to outer shelf suggest that much of its surface was little modified during the late Pleistocene/Holocene transgression. Thus the late Pleistocene/Holocene transgression may have been characterized by short periods when sea level rose rapidly allowing for the preservation of relict features. (C) 2001 Elsevier Science B.V. All rights reserved.}, issn = {0025-3227}, doi = {10.1016/S0025-3227(00)00106-7}, author = {Uchupi, E. and Driscoll, N. and Ballard, R. D. and Bolmer, S. T.} } @article {818, title = {Late Quaternary stratigraphy, Paleoclimate and neotectonism of the Persian (Arabian) Gulf region}, journal = {Marine Geology}, volume = {160}, year = {1999}, note = {214vaTimes Cited:31Cited References Count:58}, month = {Aug}, pages = {1-23}, abstract = {The last glacial deposits in the Persian (Arabian) Gulf consist of a > 22,000 year old paralic terrigenous sequence in the Mesopotamia Shelf, the foredeep in front of the Iranian Zagros Mountains and the northern side of the Biaban Shelf. Elsewhere, the Gulf, and probably the Biaban Shelf, were mantled by > 30,000 year old carbonates. Comparison of C-14 data from foraminifera from the last glacial terrigenous unit in the foredeep off Iran with curves published by Hopley [Hopley, D., 1982. The Geomorphology of the Great Barrier Reef: Quaternary Development of Coral Reefs. Wiley, New York, 453 pp.] and Chapell et al. [Chapell, J., Omura, A., Tezer, E., McCulloch, M., Pandolfi, J., Ota, Y., Pillans, B., 1996. Reconciliation of late Quaternary sea levels derived from coral terraces at Huon Peninsula with deep sea oxygen isotope records. Earth Planet. Sci. Lett. 141, 227-236.] indicates that the region may have experienced uplift during the last glacial, whereas other geologic data indicate that the foredeep has had a history of continuous subsidence during the Cenozoic. A possible explanation for this discrepancy is that the foraminifera analyzed are not in place, but were reworked into shallower water during the Holocene transgression. However, the foraminifera analyzed do not display any evidence of wear, indicating that such transport was limited. A third alternative is that sea level during the last glacial was much higher than indicated by the curves of Hopley and Chapell et al.At the peak of the last glaciation 21,000 to 20,000 years ago, when sea level was 120 m lower than now, the Gulf was a waterless basin and deposition was negligible. On the Biaban Shelf, the Holocene transgressive sequence resting unconformably on last glacial sediments consists of 14,000 year old carbonates, a > 11,000 year old terrigenous delta on the northern end of the Biaban Shelf and 11,000-10,000 year old intertidal-tidal aragonite deposited in a dry climate. On the northeast side of the Gulf, the last glacial sediments are covered by 10,000 to 7000 year old aragonite muds (younging toward the northwest). Resting on the aragonites on the Biaban Shelf and on the northeast and northwest sides of the Gulf are marls deposited under the present humid climate. The southwest side of the Gulf continued to be a site of carbonate deposition throughout the Holocene. Comparison of AMS C-14 measurements of the late Holocene marls with the sea level curve of Fairbanks [Fairbanks, R.G., 1989. A 17,000 year glacio-eustatic sea level record; influence of glacial melting rates and the Younger Dryas event and deep-ocean circulation. Nature 342, 637-642.] indicates that the axial zone of the Gulf off Iran experienced subsidence during the Holocene. This subsidence coupled with a rapid rise in sea level during a major glacial melt 9500 to 8500 years ago, when global sea level rose from -50 to -28 m, led to the replacement of marl with a shallow (8-25 m) water fauna by a {\textquoteright}deep{\textquoteright} (> 50 m) water one. Similar measurements and other geologic data indicate that the Mesopotamia Shelf and the mouth of the Mesopotamian Depression on the northwest side of the Gulf underwent both subsidence and uplift during the Cenozoic. These vertical oscillations, however, were more subdued than these in the foredeep off iran. The Arabian Shelf along the Gulfs southwest side appears to have experienced minor uplift during the Cenozoic. (C) 1999 Elsevier Science B.V. All rights reserved.}, issn = {0025-3227}, doi = {10.1016/S0025-3227(99)00011-0}, author = {Uchupi, E. and Swift, S. A. and Ross, D. A.} } @conference {1776, title = {Relative Sea-Level Rise and the Development of Channel-Fill and Shallow-Water Sequences on Cape Cod, Massachusetts}, booktitle = {American Geophysical Union, Spring Meeting}, year = {1999}, note = {id: 120}, month = {1999}, address = {Boston, MA}, author = {Gutierrez, B. T. and Aubrey, D. G. and Driscoll, N. W. and Uchupi, E.} } @article {2434, title = {Concentrations of carbonyl compounds and the carbon isotopy of formaldehyde at a coastal site in Nova Scotia during the NARE summer intensive}, journal = {Journal of Geophysical Research: AtmospheresJ. Geophys. Res.}, volume = {101}, year = {1996}, month = {1996}, pages = {28961 - 28970}, keywords = {0315 Biosphere/atmosphere interactions, 0345 Pollution: urban and regional, 0365 Troposphere: composition and chemistry, 0394 Instruments and techniques}, isbn = {2156-2202}, doi = {10.1029/95JD03574}, url = {http://dx.doi.org/10.1029/95JD03574}, author = {Tanner, Roger L. and Zielinska, Barbara and Uberna, Ewa and Harshfield, Gregory and McNichol, Ann P.} } @article {786, title = {Concentrations of carbonyl compounds and the carbon isotopy of formaldehyde at a coastal site in Nova Scotia during the NARE summer intensive}, journal = {Journal of Geophysical Research-Atmospheres}, volume = {101}, year = {1996}, note = {Vz788Times Cited:38Cited References Count:42}, month = {Dec 20}, pages = {28961-28970}, abstract = {The concentrations of gaseous atmospheric carbonyl compounds have been measured at a coastal site on the southern tip of Nova Scotia during August 1993 as part of the National Oceanic and Atmospheric Administration{\textquoteright}s North Atlantic Regional Experiment (NARE) summer intensive. The DNPH-cartridge technique was used for sampling, with analysis by HPLC with UV absorbance detection. The carbon isotopic content of formaldehyde was measured using a novel collection technique on bisulfite-coated fillers followed by accelerator mass spectrometric determination of C-14 content and C-13/C-12 isotopic ratios. Results from this study indicate that quantifiable levels above about 100 parts per trillion by volume were found at the Chebogue Point, Nova Scotia, site for several carbonyls, formaldehyde, acetaldehyde, acetone, propionaldehyde, methyl ethyl ketone, and benzaldehyde, for most 6-hour sampling periods. Six-hour averaged formaldehyde levels of <0.5 to about 3.5 parts per billion were found during periods of local influence and during influence of continental air masses crossing eastern Canada and northeastern US. In contrast, background levels of formaldehyde of 200-400 pptv were found under conditions of predominantly marine back trajectories. Large fractions of contemporary carbon (of the order of 80\%) were found in collected formaldehyde samples for all transport regimes and formaldehyde concentrations, suggesting that biogenic sources of hydrocarbon precursors to formaldehyde predominated during the summer season.}, issn = {2169-897x}, doi = {10.1029/95jd03574}, author = {Tanner, R. L. and Zielinska, B. and Uberna, E. and Harshfield, G. and McNichol, A. P.} } @article {852, title = {Gas venting and late Quaternary sedimentation in the Persian (Arabian) Gulf}, journal = {Marine Geology}, volume = {129}, year = {1996}, note = {Tv774Times Cited:49Cited References Count:82}, month = {Jan}, pages = {237-269}, abstract = {High resolution 3.5 kHz echo sounding profiles and piston cores were used to reconstruct the microtopography and late Quaternary depositional history of the Persian Gulf. Perversive throughout the seafloor of the Gulf is an extensive network of pockmarks formed by seepages of thermogenic gas. These gas seeps and bottom water exiting the Gulf via the Strait of Hormuz are the most significant processes controlling present-day sedimentation in the region. Erosion by these seeps has been so intense in the Baiban Shelf in the Strait of Hormuz as to create a {\textquoteright}{\textquoteright}hoodoo{\textquoteright}{\textquoteright} like terrain on the outer shelf. The surfical geology of the Gulf documents a short lived transgression 29,400 to 22,800 years ago during the Wisconsin regression which began 125,000 years ago, the Wisconsin regressive maxima when sea level dropped to -120/-130 m about 21,000/20,000 years ago and the climate was dry and eolian and paralic sedimentation characterized the Gulf, the Holocene transgression 18,000 to 12,000 years ago when the climate was more humid than during the climax of the Wisconsin regression, a dry phase 12,000 to 9000 years ago when the Persian Gulf was a site of eolian and carbonate deposition, and the present sediment cycle during the last 9000 years under a more humid regime. It was during the present cycle that southeast trending marl lobes were deposited off Iran, Arabia acquired its hyper-arid climate about 3000 years ago and the Gulf attained its present configuration about 1000 years ago as a result of the construction of the Tigris Euphrates Delta at its head and tectonism and aggradation along its Arabian and Iranian flanks.}, issn = {0025-3227}, doi = {10.1016/0025-3227(96)83347-0}, author = {Uchupi, E. and Swift, S. A. and Ross, D. A.} } @article {740, title = {Increased continental-margin slumping frequency during sea-level lowstands above gas hydrate-bearing sediments}, journal = {Geology}, volume = {24}, year = {1996}, note = {Tt580Times Cited:86Cited References Count:26}, month = {Feb}, pages = {143-146}, abstract = {We present C-14 data on sediment samples from cores of the upper 7 m of the sediment column overlying a major continental-rise gas hydrate field on the southern Carolina Rise and inner Blake Ridge offshore the southeastern United States. The data show that glacial-age sediments are underrepresented in the cores. The observation is consistent with a previously predicted association between sea-level lowstands and increased frequency of sea-floor slumping on continental margins containing gas hydrates.}, issn = {0091-7613}, doi = {10.1130/0091-7613(1996)024<0143:Icmsfd>2.3.Co;2}, author = {Paull, C. K. and Buelow, W. J. and Ussler, W. and Borowski, W. S.} }