scholarly journals Potential of Stable Carbon and Oxygen Isotope Variations of Speleothems from Andaman Islands, India, for Paleomonsoon Reconstruction

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Amzad H. Laskar ◽  
S. Raghav ◽  
M. G. Yadava ◽  
R. A. Jani ◽  
A. C. Narayana ◽  
...  
Keyword(s):  
Monsoon Rainfall ◽  
Boreal Summer ◽  
Stable Carbon ◽  
The South ◽  
Isotopic Equilibrium ◽  
The Past ◽  
Carbon And Oxygen Isotope ◽  
Show Evidence ◽  
Oxygen Isotopic ◽  
India Receive

The Indian monsoon activity, coinciding with the Inter-Tropical Convective Zone (ITCZ), progresses from the southern Indian Ocean during the boreal summer and withdraws towards the south in winter. Islands situated to the south of India receive, therefore, the first and last showers of the monsoon; speleothems in such islands have not yet been explored for their potential to reconstruct past monsoon rainfall. Here, we present the first measurements of stable carbon and oxygen isotopic compositions (δ13C and δ18O) of a stalagmite collected from the Baratang Island of Andamans, along with new data on δ18O of modern monsoon precipitation (May to July 2010). The aim was to detect (i) whether these samples are amenable to dating using 14C, (ii) whether their oxygen isotopes indicate precipitation under isotopic equilibrium, and (iii) if (i) and (ii) above are true, can we reconstruct monsoon activity during the past few millennia? Our results indicate that while δ18O of speleothem does show evidence for precipitation under isotopic equilibrium; dating by 14C shows inversions due to varying contributions from dead carbon. The present work highlights the problems and prospects of speleothem paleomonsoon research in these islands.

The utility of stable isotopic signatures in coral skeletons

1996 ◽  
Vol 1 ◽  
pp. 249-291 ◽  
Author(s):  
Peter K. Swart ◽  
Jim J. Leder
Keyword(s):  
Isotopic Composition ◽  
Dissolved Inorganic Carbon ◽  
Carbon Isotopic Composition ◽  
Oxygen Isotopic Composition ◽  
Stable Carbon ◽  
Carbon And Oxygen Isotopes ◽  
Coral Skeletons ◽  
Carbon And Oxygen Isotope ◽  
Oxygen Isotopic ◽  
Zooxanthellate Corals

There is a fundamental ecologic differentiation between zooxanthellate and non-zooxanthellate corals. This paper reviews factors which govern the stable carbon and oxygen isotopic composition of these groups of corals. Although the stable carbon and oxygen isotope compositions of coral skeletons are strongly influenced by environmental and physiological factors, the precise mechanisms remain a matter of debate. In particular the oxygen isotopic composition is known to be governed by the temperature and the oxygen isotopic composition of the water and perhaps also by kinetic factors. In contrast the carbon isotopic composition is controlled by a combination of photosynthesis, respiration, autotrophy, heterotrophy, and the isotopic composition of dissolved inorganic carbon. Using a combination of carbon and oxygen isotopes it is possible to distinguish zooxanthellate from non-zooxanthellate corals.

Stable carbon and oxygen isotope record in the Paleogene La Meseta Formation, Seymour Island, Antarctica

1992 ◽  
Vol 4 (4) ◽  
pp. 461-468 ◽  
Author(s):  
Andrzej Gaździcki ◽  
Michał Gruszczyński ◽  
Antoni Hoffman ◽  
Krzysztof Małkowski ◽  
Sergio A. Marenssi ◽  
...  
Keyword(s):  
Middle Part ◽  
Weddell Sea ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
Early Oligocene ◽  
Oxygen Isotope Record ◽  
Carbon And Oxygen Isotope ◽  
La Meseta Formation ◽  
Isotope Record ◽  
Oxygen Isotopic

Stable carbon and oxygen isotopic relations have been analysed in brachiopod, gastropod, and bivalve fossils from the La Meseta Formation (Eocene-?early Oligocene), Seymour (Marambio) Island, West Antarctica. The results indicate a shift in δ13C by 6 permil beginning in the middle part of the Unit II of the formation. This shift may imply a change from a largely stratified to a vigorously mixed ocean. Such an interpretation is corroborated by changes in the elemental proportions in the shell material. Alternatively, the carbon isotopic shift may be regarded as reflecting a change in the local depositional enviornment. Such an interpretation agrees with isotopic data from the Weddell Sea, which do not confirm the pattern observed in the La Meseta Formation. In any event, the oxygen isotopic curve does not decline parallel to the carbon curve and may thus imply a considerable climatic cooling event. This effect is so profound that it might be interpreted as evidence for glaciation, especially when taking into account the fact that this phenomenon coincides with the well-known cooling trend throughout the Eocene. If this interpretation is correct, the hypothesized Glaciation may possibly be correlated with the Polonez Glaciation, the largest Cenozoic glaciation known in the Antarctic Peninsula sector. Alternatively, it may be regarded as a local phenomenon, predating development of the icesheet.

scholarly journals Publisher Correction: Record warming at the South Pole during the past three decades

2021 ◽  
Author(s):  
Kyle R. Clem ◽  
Ryan L. Fogt ◽  
John Turner ◽  
Benjamin R. Lintner ◽  
Gareth J. Marshall ◽  
...  
Keyword(s):  
South Pole ◽  
The South ◽  
The Past

scholarly journals Monitoring Changes in the Transparency of the Largest Reservoir in Eastern China in the Past Decade, 2013–2020

2021 ◽  
Vol 13 (13) ◽  
pp. 2570
Author(s):  
Teng Li ◽  
Bozhong Zhu ◽  
Fei Cao ◽  
Hao Sun ◽  
Xianqiang He ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mean Squared Error ◽  
Eastern China ◽  
Water Environment ◽  
Relative Difference ◽  
Boreal Summer ◽  
Support Vector ◽  
Lake Area ◽  
The Past ◽  
Remote Sensing Reflectance

Based on characteristics analysis about remote sensing reflectance, the Secchi Disk Depth (SDD) in the Qiandao Lake was predicted from the Landsat8/OLI data, and its changing rates on a pixel-by-pixel scale were obtained from satellite remote sensing for the first time. Using 114 matchups data pairs during 2013–2019, the SDD satellite algorithms suitable for the Qiandao Lake were obtained through both the linear regression and machine learning (Support Vector Machine) methods, with remote sensing reflectance (Rrs) at different OLI bands and the ratio of Rrs (Band3) to Rrs (Band2) as model input parameters. Compared with field observations, the mean absolute relative difference and root mean squared error of satellite-derived SDD were within 20% and 1.3 m, respectively. Satellite-derived results revealed that SDD in the Qiandao Lake was high in boreal spring and winter, and reached the lowest in boreal summer, with the annual mean value of about 5 m. Spatially, high SDD was mainly concentrated in the southeast lake area (up to 13 m) close to the dam. The edge and runoff area of the lake were less transparent, with an SDD of less than 4 m. In the past decade (2013–2020), 5.32% of Qiandao Lake witnessed significant (p < 0.05) transparency change: 4.42% raised with a rate of about 0.11 m/year and 0.9% varied with a rate of about −0.09 m/year. Besides, the findings presented here suggested that heavy rainfall would have a continuous impact on the Qiandao Lake SDD. Our research could promote the applications of land observation satellites (such as the Landsat series) in water environment monitoring in inland reservoirs.

scholarly journals Our New Cathedrals: Spirituality and Old-Growth Forests in Western Australia

2006 ◽  
Vol 3 (1) ◽  
Author(s):  
David Worth
Keyword(s):  
Social Movements ◽  
Western Australia ◽  
The State ◽  
The South ◽  
Old Growth ◽  
The Past ◽  
South West ◽  
Old Growth Forests ◽  
Heated Debate ◽  
Policy Proposals

Over the past 30 years in Western Australia (WA), there has been heated debate about the future use of the remaining karri and jarrah forests in the south-west of the State. This debate revolves around policy proposals from two social movements: one wants to preserve as much of the remaining old-growth forests as possible, and an opposing movement supports a continued

scholarly journals Connection between Anomalous Zonal Activities of the South Asian High and Eurasian Summer Climate Anomalies

2016 ◽  
Vol 29 (22) ◽  
pp. 8249-8267 ◽  
Author(s):  
Jian Shi ◽  
Weihong Qian
Keyword(s):  
South Asian ◽  
Surface Air Temperature ◽  
Northern China ◽  
Boreal Summer ◽  
South Asian High ◽  
The South ◽  
Climate Anomalies ◽  
Precipitation Anomalies ◽  
Air Column ◽  
Air Temperature Anomalies

Abstract Using the daily mean anomalies of atmospheric variables from the NCEP Reanalysis-1 (NCEP R1), this study reveals the connection between anomalous zonal activities of the South Asian high (SAH) and Eurasian climate anomalies in boreal summer. An analysis of variance identifies two major domains with larger geopotential height variability located in the eastern and western flanks of the SAH at around 100 and 150 hPa, respectively. For both eastern and western domains, extreme events are selected during 1981–2014 when normalized height anomalies are greater than 1.0 (less than −1.0) standard deviation for at least 10 consecutive days. Based on these events, four SAH modes that include strong and weak Tibetan modes (STM and WTM, respectively) and strong and weak Iranian modes (SIM and WIM, respectively) are defined to depict the zonal SAH features. The positive composite in the eastern (western) domain indicates the STM (SIM) manifests a robust wavelike pattern with an anomalous low at 150 hPa, and surface cold and wet anomalies over Mongolia and northern China (Kazakhstan and western Siberia) are surrounded by three anomalous highs at 150 hPa and surface warm and dry anomalies over Eurasia. Opposite distributions are also evident in the negative composites of the two domains (WTM and WIM). The surface air temperature anomalies are the downward extension of an anomalous air column aloft while the precipitation anomalies are directly associated with the height anomalies above the air column.

Stable carbon and oxygen isotope compositions of extant crinoidal echinoderm skeletons

2012 ◽  
Vol 291 ◽  
pp. 132-140 ◽  
Author(s):  
Przemysław Gorzelak ◽  
Jarosław Stolarski ◽  
Krzysztof Małkowski ◽  
Anders Meibom
Keyword(s):  
Oxygen Isotope ◽  
Stable Carbon ◽  
Carbon And Oxygen Isotope

scholarly journals Late Pleistocene human paleoecology in the highland savanna ecosystem of mainland Southeast Asia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kantapon Suraprasit ◽  
Rasmi Shoocongdej ◽  
Kanoknart Chintakanon ◽  
Hervé Bocherens
Keyword(s):  
Southeast Asia ◽  
Late Pleistocene ◽  
Tooth Enamel ◽  
Stable Carbon Isotope ◽  
Lower Latitude ◽  
Stable Carbon ◽  
Hunter Gatherers ◽  
Carbon And Oxygen Isotope ◽  
Northwestern Thailand ◽  
Mainland Southeast Asia

AbstractThe late Pleistocene settlement of highland settings in mainland Southeast Asia by Homo sapiens has challenged our species’s ability to occupy mountainous landscapes that acted as physical barriers to the expansion into lower-latitude Sunda islands during sea-level lowstands. Tham Lod Rockshelter in highland Pang Mapha (northwestern Thailand), dated between 34,000 and 12,000 years ago, has yielded evidence of Hoabinhian lithic assemblages and natural resource use by hunter-gatherer societies. To understand the process of early settlements of highland areas, we measured stable carbon and oxygen isotope compositions of Tham Lod human and faunal tooth enamel. Our assessment of the stable carbon isotope results suggests long-term opportunistic behavior among hunter-gatherers in foraging on a variety of food items in a mosaic environment and/or inhabiting an open forest edge during the terminal Pleistocene. This study reinforces the higher-latitude and -altitude extension of a forest-grassland mosaic ecosystem or savanna corridor (farther north into northwestern Thailand), which facilitated the dispersal of hunter-gatherers across mountainous areas and possibly allowed for consistency in a human subsistence strategy and Hoabinhian technology in the highlands of mainland Southeast Asia over a 20,000-year span near the end of the Pleistocene.

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