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Multi Proxy Stable Isotope Analyses Of Late Holocene Precipitation Variability And Vegetation Change At Laguna Maria Aguilar Costa Rica
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Book Synopsis Multi-proxy Stable Isotope Analyses of Late Holocene Precipitation Variability and Vegetation Change at Laguna María Aguilar, Costa Rica by : Phyllis Yu Yi Kho
Download or read book Multi-proxy Stable Isotope Analyses of Late Holocene Precipitation Variability and Vegetation Change at Laguna María Aguilar, Costa Rica written by Phyllis Yu Yi Kho and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Compound-specific Stable Isotope Analyses of Late-holocene Vegetation and Precipitation Change at Laguna Los Mangos by : Elizabeth A. Yanuskiewicz
Download or read book Compound-specific Stable Isotope Analyses of Late-holocene Vegetation and Precipitation Change at Laguna Los Mangos written by Elizabeth A. Yanuskiewicz and published by . This book was released on 2019 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Holocene Climate Variability in Hispaniola by : Elizabeth Marie MacLennan
Download or read book Holocene Climate Variability in Hispaniola written by Elizabeth Marie MacLennan and published by . This book was released on 2019 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laguna Saladilla (19.656 N, 71.715 W) is a large (220 ha) freshwater lake located near sea level on the north coast of Hispaniola, 2 km south of Monte Cristi National Park in the Dominican Republic, and 1 km east of the international border with Haiti. Results of prior analyses of pollen, microscopic charcoal, mollusk shells, and diatoms in an 8.5-m sediment core from the lake were interpreted to largely indicate shifts in salinity and water depth attributed to relative sea level rise over the middle and late Holocene (Caffrey et al., Paleogeography, Paleoecology, Paleoclimatology 436: 9-32, 2015). Mollusk assemblages indicated saline conditions at 7650 cal yr BP, when sediments contained abundant red mangrove pollen, but freshening over the late Holocene, with the lake becoming brackish at 3500 cal yr BP and transitioning ca. 2500 cal yr BP to its current freshwater condition. Increased charcoal abundance and higher percentages of Amaranthaceae pollen after 2500 cal yr BP indicate increased fires and generally dry climate in coastal north Hispaniola, but detailed climate reconstruction was not possible from the proxies examined. To develop a precipitation record for north coastal Hispaniola, I examined compound-specific hydrogen isotopes in 39 samples covering the last ca. 1700 years at Laguna Saladilla. I also analyzed hydrogen isotopes in samples of bulk sediment covering this same period. Results provided evidence of increased aridity and evapotranspiration/precipitation ratios during the time known as the Terminal Classic Drought. Results complement and extend prior proxy analyses, illustrating the benefits of hydrogen isotopes in the reconstruction of paleoenvironments. My research also tested the correlation of sedimentary bulk hydrogen to compound-specific hydrogen isotopes, showing that bulk hydrogen isotopes did not respond the same controls as the compound-specific record at this site. The correlation of bulk hydrogen isotopes to other proxies at Laguna Saladilla, however, suggest that it is still a useful proxy for understanding past environments. This research extends upon the work of multiple studies to reconstruct climate changes during the Terminal Classic Drought in the circum-Caribbean region.
Book Synopsis Isotopes in Palaeoenvironmental Research by : Melanie J. Leng
Download or read book Isotopes in Palaeoenvironmental Research written by Melanie J. Leng and published by Springer Science & Business Media. This book was released on 2006-03-09 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thorough reference shows how stable isotopes can be applied to understanding the palaeoenvironment, with chapters on the interpretation of isotopes in water, tree rings, bones and teeth, lake sediments, speleothems and marine sediments. The book offers detailed advice on calibration, including a multi-proxy approach, using isotope signals from different materials or combined with other palaeoenvironmental techniques, to enhance the reliability of readings.
Book Synopsis Compound-specific Hydrogen Isotope Analysis of Lacustrine Sediments to Establish Late-Holocene Paleoprecipitation Dynamics at Laguna Arancibia, Costa Rica by : Amanda Tomlinson
Download or read book Compound-specific Hydrogen Isotope Analysis of Lacustrine Sediments to Establish Late-Holocene Paleoprecipitation Dynamics at Laguna Arancibia, Costa Rica written by Amanda Tomlinson and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydrogen, Carbon, and Oxygen Isotopes in Prosopis Sp. Trees by : Elizabeth Joy Olson
Download or read book Hydrogen, Carbon, and Oxygen Isotopes in Prosopis Sp. Trees written by Elizabeth Joy Olson and published by . This book was released on 2018 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spatial ubiquity of trees in terrestrial ecosystems worldwide facilitates the use of stable isotope research in tree-rings to address a wide-range of interdisciplinary questions related to climate, ecology, archaeology, and hydrology. This dissertation focuses on the development and application of Prosopis tamarugo tree-ring stable isotope records as a paleoclimate proxy for the Atacama Desert, Chile. Current paleoclimate proxies from this region lack the spatial and temporal resolution to quantify a causal mechanism for observed Holocene hydroclimate variability. P. tamarugo tree-ring isotopes provide a high-resolution proxy that facilitates the reconstruction of hydroclimate variability at a regional scale. In order to address this issue, annual and subannual hydrogen ([delta]2H[sub ac]), oxygen ([delta]18O[sub ac]) and, carbon ([delta]13C[sub ac]) isotope records of [alpha]-cellulose measured in modern P. tamarugo tree rings are used to evaluate the use of this species for climatic reconstruction. Correlation-based analysis over the past half-century (1954-2016) reveals that tree isotopes record hydroclimate conditions, including changes in vapor-pressure deficit and groundwater isotope variability/depth. Modern groundwater depth was successfully modeled from the [delta]18O[sub ac] and [delta]2H[sub ac] values of modern tree-branch a-cellulose. Based on the modern calibration dataset, tree-ring [delta]18O[sub ac] and [delta]13C[sub ac] values of ancient Prosopis sp. are interpreted as a record of regional hydroclimate variability over the Holocene. A discontinuous record of Prosopis sp. tree-ring [delta]18O[sub ac] and [delta]13C[sub ac] isotopes radiocarbon date between 9,500 and 1,200 years ago. These records provide evidence of changes in relative humidity and groundwater availability (via plant intrinsic-water use efficiency) in the Atacama Desert over the Holocene. There is a steady increase in intrinsic water-use efficiency from the early to late Holocene, indicating a regional reduction in the availability of groundwater resources. [delta]18O[sub ac]-based estimates of relative humidity (h) show increased atmospheric moisture variability beginning 4,900 years ago and continuing through to the present. A strong correlation (r = 0.96) between the average [delta]18O[sub ac] values of the Atacama tree-rings and the high Andean Sajama [delta]18O ice core record provides evidence that water availability in the Atacama Desert is linked with high altitude Andean precipitation over the last 9,500 years. The tree-ring isotope series provide a discontinuous, but annually resolved, proxy that is the highest resolution record yet developed for the Atacama Desert. This research provides evidence that Prosopis sp. trees are high-resolution archives of hydroclimate change and suggests that future exploration of arid-region tree species isotope records could increase the spatial coverage of paleoclimate records worldwide.
Book Synopsis Problems of Stable Isotopes in Tree-rings, Lake Sediments and Peat-bogs as Climatic Evidence for the Holocene by : Burkhard Frenzel
Download or read book Problems of Stable Isotopes in Tree-rings, Lake Sediments and Peat-bogs as Climatic Evidence for the Holocene written by Burkhard Frenzel and published by Wiley-VCH. This book was released on 1995 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Stable Isotope Analysis of Lake Sediments from Laguna Santa Elena and Laguna Azul, Costa Rica by : Matthew Timothy Kerr
Download or read book Stable Isotope Analysis of Lake Sediments from Laguna Santa Elena and Laguna Azul, Costa Rica written by Matthew Timothy Kerr and published by . This book was released on 2014 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake sediments are increasingly important archives of human-environment interactions and paleoclimate in the neotropics. In Costa Rica, Anchukaitis and Horn (Palaeogeography, Palaeoclimatology, Palaeoecology 221: 35-54, 2005) established a land-use history for Laguna Santa Elena (8.9306 N, 82.9275 W, 1055 m elevation), a small lake in the Diquís archaeological region, based on pollen and charcoal analyses of a 7-meter sediment core. I carried out stable carbon and nitrogen isotope and loss-on-ignition analyses at higher resolution to extend the existing 2000-year record. The new geochemical data parallel major trends in botanical proxies but also reveal aspects of human and environmental dynamics not apparent in the prior analysis. Inferred changes in land use in the watershed are consistent with archaeological evidence. Geochemical trends strongly suggest a population collapse at the site around the time of the Terminal Classic Drought of the Mayan region. The generally close correspondence between microfossil assemblages and geochemistry in the Santa Elena core demonstrates the usefulness of stable isotope analysis as a first line of investigation in paleoenvironmental research. Sediment samples for carbon isotope analysis need to be acidified to remove carbonates that can affect isotope measurements, and debate exists over whether nitrogen isotope analysis can use these acidified samples or require non-acidified samples. My thesis research tested the effects of pre-analysis acidification of sediment and soil samples from Laguna Santa Elena and a second lake in Costa Rica, Laguna Azul (9.9558 N, 83.6519 W, 630 m elevation) in the Central Highlands-Atlantic Watershed archaeological region. Results show that acidification may cause statistically significant differences in nitrogen isotope values. These differences appear to be random and unpredictable, and can manifest as either positive or negative shifts that have the potential to alter or even reverse relative trends in nitrogen isotope signals in lake sediment profiles. More tests are needed, but the results of this analysis suggest that researchers should avoid dual-mode analysis, in which data for both stable carbon and nitrogen isotopes are obtained from a single acidified sample, and should continue analyzing an additional non-acidified sample to obtain nitrogen isotope values.
Book Synopsis Holocene Climate Variability in the Mexican Monsoon Region by : Benjamin John Aston
Download or read book Holocene Climate Variability in the Mexican Monsoon Region written by Benjamin John Aston and published by . This book was released on 2008 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Climate Variability During the Holocene and Last Interglacial by : Julie Elizabeth Friddell
Download or read book Climate Variability During the Holocene and Last Interglacial written by Julie Elizabeth Friddell and published by . This book was released on 2001 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene Climate Change for the Eastern Interior United States by : Christopher M. Wurster
Download or read book Late Holocene Climate Change for the Eastern Interior United States written by Christopher M. Wurster and published by . This book was released on 1999 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Palaeoclimates and Palaeowaters by : International Atomic Energy Agency
Download or read book Palaeoclimates and Palaeowaters written by International Atomic Energy Agency and published by . This book was released on 1983 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigating late Holocene climate variability in central Mexico using carbon isotope ratios in organic materials and oxygen isotope ratios from diatom silica within lacustrine sediments by : M.J. Leng
Download or read book Investigating late Holocene climate variability in central Mexico using carbon isotope ratios in organic materials and oxygen isotope ratios from diatom silica within lacustrine sediments written by M.J. Leng and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene Climate Variability from Northern Gulf of Mexico Sediments by : Julie N. Richey
Download or read book Late Holocene Climate Variability from Northern Gulf of Mexico Sediments written by Julie N. Richey and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Accurate reconstruction of natural climate variability over the past millennium is critical for predicting responses to future climate change. In order to improve on current understanding of climate variability in the sub-tropical North Atlantic region over the past millennium, a rigorous study of Gulf of Mexico (GOM) sea surface temperature (SST) variability was conducted using both inorganic (foraminiferal Mg/Ca) and molecular organic (TEX6) geochemical proxies. In addition to generating multiple high-resolution climate records, the uncertainties of the SST proxies are rigorously assessed. There are 3 major research questions addressed: (1) What was the magnitude of GOM SST variability during the past 1,000 years, particularly during large-scale climate events such as the Little Ice Age (LIA) and the Medieval Warm Period (MWP). (2) Is the SST signal reproducible within the same sediment core, among different northern GOM basins, and using different geochemical SST proxies? (3) What are the ecological controls on the paleothermometers used to reconstruct SST variability in the GOM? Can differences in the ecology (i.e. seasonal distribution, depth habitat, etc.) of distinct paleothermometers be exploited to gain insight into changes in upper water column structure or seasonality in the GOM during the LIA and MWP? The major findings include: (1) The magnitude of temperature variability in the GOM over the past millennium is much larger than that estimated from Northern Hemisphere temperature reconstructions. The MWP (1400-900 yrs BP) was characterized by SSTs in the GOM that were similar to the modern SST, while the LIA (400-150 yrs BP) was marked by a series of multidecadal intervals that were 2-2.5°C cooler than modern. (2) This LIA cooling was replicated in the Mg/Ca-SST records from three different well-dated northern GOM basins (Pigmy, Garrison and Fisk Basins), as well as in two different geochemical proxies. (3) It is determined that foraminiferal test size has a significant effect on shell geochemistry. Using core-top calibration, discrepancies in the seasonal/depth habitats between different planktonic Foraminifera, and between Foraminifera and Crenarchaeota are inferred. Downcore differences are used to make inferences about changes in GOM mixed layer depth and seasonality over the past millennium.
Book Synopsis Multi-proxy Stable Oxygen and Carbon Isotope Evidence for Holocene Climate Change in Western Ireland by : Martin Collett
Download or read book Multi-proxy Stable Oxygen and Carbon Isotope Evidence for Holocene Climate Change in Western Ireland written by Martin Collett and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Use of Stable Isotopes and GIS Modeling to Study Late Pleistocene to Holocene Environmental Change in the Waipaoa Sedimentary System, New Zealand by :
Download or read book Use of Stable Isotopes and GIS Modeling to Study Late Pleistocene to Holocene Environmental Change in the Waipaoa Sedimentary System, New Zealand written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The source to sink investigation of complex sedimentary systems necessitates chemical (stable isotope and elemental) and physical (modeling) analyses to elucidate temporal changes in volume and provenance of sediment supply. The stable isotopic composition of organic matter in continental margin sediments provides a useful, long-term record of environmental change. The Waipaoa River watershed, New Zealand, represents a system of interest due to its location on an active margin, very large sediment supply, and well known, relatively recent history of anthropogenic disturbance. Radiocarbon measurements of three continental shelf cores taken aboard the RV Marion Dufresne in January 2006 offshore from the river mouth suggest a record extending into the late Pleistocene, dating as far back as 14,000 years. Geographic information systems (GIS) modeling suggests large increases in erosion with reduction in landcover due to natural volcanic events and anthropogenic disturbances. Carbon and nitrogen isotope analyses of terrestrial sources including soil profiles, sedimentary rocks and riverine sediments from within the watershed suggest terrestrial processes such as shoreline progradation, hillslope erosion and gully incision, volcanic eruptions, and the capture of river tributaries are possibly influencing isotopic ratios and impacting the marine stratigraphic record. Unique isotopic signatures of soil profiles from disparate areas of the watershed could explain some isotopic variation seen in the cores as deviation in delivery volume from certain tributaries. Within the marine record in all three cores exists a distinct excursion of carbon isotopes to more positive values. Possible explanations for this include: 1) an increase in the flux of an isotopically heavy terrestrial fraction from the erosion of kerogen and 2) a decrease in the proportion of terrestrial organic matter due to dilution of river sediments with volcanic ash. Increasing nitrogen isotope values also with.
Book Synopsis Late Holocene Oxygen Isotope Record of Hydroclimate Variability in Nicaragua from Lake Asososca by : Stephen Perdziola
Download or read book Late Holocene Oxygen Isotope Record of Hydroclimate Variability in Nicaragua from Lake Asososca written by Stephen Perdziola and published by . This book was released on 2018 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of hydroclimate requires a higher level of spatial and temporal detail than what currently exists for Central America. High resolution lake sediment archives are critical to gaining a more complete understanding of late Holocene climate variability in the region. The climate of Central America is influenced by both tropical Atlantic and Pacific Ocean-atmosphere processes. A better understanding of how these processes have impacted regional hydroclimate is important as it will enable more accurate predictions of future climate changes associated with shifting conditions in a drought sensitive region. Here a 1,000-year carbonate oxygen isotope record is presented from Lake Asososca, located in western Nicaragua. In this record, high delta 18O values indicate drier conditions, while lower ?18O values indicate drier conditions. My data indicate wet conditions at the start of the Medieval Climate Anomaly (MCA) and a trend towards drier conditions until A.D. 1200. The transitional period between the MCA and the Little Ice Age (LIA) from A.D. 1200 - 1400 experienced a shift towards wetter conditions. The LIA from A.D. 1400 -- 1850 was a period of variable conditions. My record indicates a shift from wet to dry conditions from A.D. 1400 - 1600. A pronounced period of wetter conditions occurred from A.D. 1650-1700 during the Maunder Minimum solar event. From A.D 1700 -- 1800 the record indicates variable conditions that alternated between shifts towards dry and wet. After the LIA, the record indicates a trend towards drier conditions. The El Nino Southern Oscillation (ENSO), the North American Oscillation (NAO), and the Atlantic Multidecadal Oscillation (AMO), were often temporally correlated with the Lake Asososca record and suggest that these modes have impacted regional hydroclimate over the late Holocene. Correspondence between the Lake Asososca record and solar variability highlight a potential linkage. Climate models indicate that the Atlantic Meridional Overturning Circulation responds to changes in solar variability and can have impacts on Atlantic SSTs, and therefore may be provide a mechanism to amplify changes in solar variability to Central American hydroclimate. Comparison of the Lake Asososca delta18O record to regional hydroclimate proxies across show little correspondence over the past millennium. While some similarities exist between the Lake Asososca record and other regional proxies, the lack of a coherent hydroclimate signal over the late Holocene suggests temporally and spatially variability hydroclimate shifts. More hydroclimate reconstructions and modelling studies need to be performed in order to fully resolve hydroclimate variability in Central America over the past millennium. This record adds to the network of regional paleoclimate reconstructions in Central America and indicates that modes of variability in both the Atlantic and Pacific Ocean basins have impacted regional hydroclimate over the past millennium.
