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Stable carbon isotopic composition of ethane and propane over the western North Pacific and eastern Indian Ocean between 31°N
and 26°S was investigated from February through March 2004. The isotopic composition of ethane ranged from −28 to −18‰ and
showed a gradual increase from north to south. Conversely, that of propane was between −31 and −24‰; it showed no systematic
latitudinal variation. Investigation of the ethane/propane ratio indicates that ethane and propane that originated from northern
mid-latitude countries in the eastern part of Eurasia were both transported into the western North Pacific region. However,
the results of the isotopic analyses indicate the contribution of oceanic emission to the atmospheric propane during transport,
although that contribution can not be discerned for ethane. A ship based stationary observation conducted in the western equatorial
North Pacific showed that the isotopic composition of ethane varied from −25 to −19‰ and showed clear systematic diurnal variation:
propane ranged between −32 to −26‰ and no such isotopic diurnal signal was observed. The diurnal variation for ethane is explained
by entrainment of free tropospheric air, whereas the variation for propane was influenced by oceanic emissions as well as
the entrainment. The contribution of oceanic emissions to the atmospheric propane inventory was considered from our isotopic
observation. Isotopic composition of dissolved propane is estimated to be less than −38‰, and the contribution up to 79% was
calculated when the isotopic composition of dissolved propane is assumed to be −40‰. Our study demonstrates that isotopic
analysis can be more useful than ratio-based analysis to improve our present understanding of transport processes, especially
for impact of the oceanic emissions on the atmospheric distribution of low level C2–C5 non-methane hydrocarbons such as propane in the remote marine atmosphere. 相似文献
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Understanding diverse characteristics of human mobility provides profound knowledge of urban dynamics and complexity. Human movements are recorded in a variety of data sources and each describes unique mobility characteristics. Revealing similarity and difference in mobility data sources facilitates grasping comprehensive human mobility patterns. This study introduces a new method to measure similarities on two origin–destination (OD) matrices by spatially extending an image‐assessment tool, the structural similarity index (SSIM). The new measurement, spatially weighted SSIM (SpSSIM), utilizes weight matrices to overcome the SSIM sensitivity issue due to the ordering of OD pairs by explicitly defining spatial adjacency. To evaluate SpSSIM, we compared performances between SSIM and SpSSIM with resampling the orders of OD pairs and conducted bootstrapping to test the statistical significance of SpSSIM. As a case study, we compared OD matrices generated from three data sources in San Diego County, CA: U.S. Census‐based Longitudinal Employer–Household Dynamics Origin–Destination employment statistics, Twitter, and Instagram. The case study demonstrated that SpSSIM was able to capture similarities of mobility patterns between datasets that varied by distance. Some regions showed local dissimilarity while the global index indicated they were similar. The results enhance the understanding of complex mobility patterns from various datasets, including social media. 相似文献
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O. Vasellil H. Downes M. F. Thirlwall R. Vannucci N. Coradossi 《Mineralogy and Petrology》1996,57(1-2):23-50
Summary Ultramafic xenoliths from the basaltic tuff of Kapfenstein (Graz Basin) are mainly protogranular and protogranular- to- porphyroclastic spinel lherzolites. In addition to these common rocks, a coarse-grained spinel harzburgite and a heterogeneous spinel peridotite consisting of a clinopyroxene-poor harzburgite and a clinopyroxene-rich lherzolite have been found. Interstitial amphiboles (pargasite and kaersutite) are present in most xenoliths. The magmatic activity which brought these xenoliths to the surface is part of the Plio-Pleistocene extension-related alkali basalt volcanism which took place in the Carpatho-Pannonian Region, post-dating the subduction-related calc-alkaline volcanism which formed the Inner Carpathian arc.Mineralogical and bulk geochemical data for Kapfenstein xenoliths are similar to those for other sub-continental shallow mantle xenolith suites. Correlation diagrams for major and trace elements indicate that their chemical variations are related to different degrees of partial melting due to the extraction of mafic melts. Rare earth element (REE) patterns of separated clinopyroxenes from the xenoliths are generally light rare earth element (LREE)-depleted, although LREE-enriched and more complex patterns have also been found.87Sr/86Sr and143Nd/.144Nd isotopic ratios of separated clinopyroxenes vary between 0.70193 and 0.70330 (Sr, = – 36.4 to –17.0) and 0.512824 and 0.513589 (NdNd = 4.2 to 18.l), respectively. The highest87Sr/86Sr and lowest1443Nd/144Nd.Nd ratios occur in those samples which have the most refractory character and also have the most unusual REE patterns. REE determined by ion microprobe on separated interstitial amphibole grains indicate equilibrium with the host peridotite in most of the xenoliths but disequilibirum conditions have been observed, including some extreme LREE enrichments.Striking textural and some geochemical and isotope geochemical similarities have been recognised between Kapfenstein xenoliths and those from the Eastern Transylvanian Basin, both of which are situated on the edges of the diapiric upwelling located in the central part of the Pannonian Basin. The deformation, depletion and enrichment processes which occurred in these two areas are thought to be similar. The LREE-enriched interstitial amphiboles and the presence of cross-cutting amphibole veins suggest that the shallow depleted lithospheric mantle beneath the Graz Basin has been affected by metasomatising events related to the mafic alkaline host magmas rather than by subduction-related fluids or melts.
With 7 Figures 相似文献
Spinel-peridotit Xenolithe von Kapfenstein (Grazer Becken, Ostösterreich): Eine geochemische und petrologische Studie
Zusammenfassung Die ultramafischen Xenolithe aus dem Basaltuff von Kapfenstein (Grazer Becken) bestehen großteils aus protogranularem und porphyroklastischem Spinell-Lherzolith. Abgesehen von diesen weitverbreiteten Gesteinen wurden auch ein grobköringer Spinell-Harzburgit und ein heterogener Spinell-Peridotit, der aus einem Klinopyroxen-armen Harzburgit und einem Klinopyroxen-reichen Lherzolith besteht, gefunden. Interstitielle Amphibole (Pargasit und Kaersutit) sind in den meisten Xenolithen vorhanden. Die magmatischen Prozesse, die diese Xenolithe an die Erdoberfläche befördeten, stehen mit dem mit Extension assoziierten Alkali-Basalt-Vulkanismus, der während des Pliozän/ Pleistozäns dem durch Subduktion ausgelösten Kalk-alkalischen Vulkanismus des inneren Karpathenbogens folgte, in Zusammenhang.Die mineralogischen und geochemischen Vollanalysen der Kapfensteiner Xenolithe sind mit den Daten von anderen Gruppen von subkontinentalen Xenolithen des oberen Mantels vergleichbar. Korrelationsdiagramme für Haupt- und Spurenelemente zeigen, daß die chemische Variation auf verschiedene Grade von Teilschmelzbildung zurück-zuführen ist. Die Verteilungsmuster der Seltenen Erden in Klinopyroxenen der Xenolithe sind generall LREE-verarmt, aber LREE angereichte und kompliziertere Verteilungsmuster kommen vor. Die87Sr/86Sr und143Nd/144Nd Isotopenverhältnisse der Klinopyroxene schwanken zwischen 0.70193 und 0.70330 (Sr = von – 36.4 bis –17.0), beziechungsweise zwischen 0.512854 und 0.513589 (Nd=von –4.2 bis 18.l). Die höchsten87Sr/86Sr und niedrigsten143Nd/144Nd Isotopenverhältnisse treten in den Proben mit dem stärksten refraktären Charakter und den ungewöhnlichsten REE-Verteilungsmustern auf. Die mittels Zonensonde ermittelten Gehalte an REE der interstitiellen Amphibole deuten ein Gleichgewicht mit dem Wirt-Peridotit an, obwohl auch Anzeichen von gestörtem Gleichgewicht, unter anderem extreme Anreicherungen an LREE, beobachtet wurden.Ein Vergleich der Kapfenstein-Xenolithe mit denen aus dem östlichen Transsylvanischen Becken zeigt bemerkenswerte strukturelle und einige geochemische und isotopengeochemische Ähnlichkeiten. Beide Gegenden befinden sich am Rande des Erdmantel diapirs, im Zentrum des Pannonischen Beckens. Die Deformationen und Verarmungsund Anreicherungsprozesse, die in beiden Gebieten stattfanden, sind vergleichbar. Die an LREE angereicherten interstitiellen Amphibole und das Auftreten von diskordanten Amphibolgängen legen nahe, daß der obere verarmte lithosphärische Mantel unter dem Grazer Becken von, mit den mafischen alkalischen Grund-Magmen verwandten, metasomatischen Prozessen erfaßt worden ist, und nicht von mit Subduktion assoziierten Flüssigkeiten oder Schmelzen.
With 7 Figures 相似文献
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ABSTRACTGeomasking techniques displace point data to new locations in order to protect privacy while maintaining overall spatial distributions. If the end users of geomasked data are unaware that the data are masked, there is a risk that they will incorrectly associate individuals at the new locations with the masked data attributes. The probability of correct and false household identification depends on human understanding of whether maps contain masked coordinates and the spatial relationships of the points to contextual geographic data. Using a map-based experiment, this study finds that confidence in performing a household identification is substantially lowered when masked points are situated equidistantly between residential parcels. Despite initial notifications that data are masked, map users often report confidence in assigning masked points to specific households. Only map users who receive frequent notifications that the points are masked have reduced confidence in associating them with particular households, thereby lowering identification risk. 相似文献
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Microbial community respiration and structure of dead zone sediments of Omura Bay, Japan 总被引：1，自引：0，他引：1
Minoru Wada Shotaro Suzuki Tadashi Nara Yu Umezawa Motohiro Shimanaga Kazumi Matsuoka Hideaki Nakata 《Journal of Oceanography》2012,68(6):857-867
Monitoring sediment microbial community metabolism and structure is instrumental to understanding biogeochemical processes in and ecological impacts on bottom environments. The aim of this study was to determine potential community respiration and to reveal community dynamics of the microorganisms in the dead zone sediments of Omura Bay, Japan. The bay is highly enclosed and develops severe hypoxia in the central regions every summer. We collected sediment core samples from the center of the bay during hypoxia, estimated sediment oxygen consumption by using an adapted in vivo electron transport system activity (in vivo ETSA) assay, enumerated abundance of bacteria, and analyzed bacterial community structure by automated ribosomal intergenic spacer analysis. Higher ETSA and bacterial diversity were found in upper sediments (within 3?cm depth) from the center than the fringe of the bay. Sediment bacterial community structure of the bay center was distinct from that of the fringe. From these results, upper sediment in the dead zone of Omura Bay was characterized by (1) greater community respiration and (2) greater diversity of bacterial components compared with the non-hypoxic sediment of the bay fringe. These characteristics have important implications for understanding the interaction between microbial communities and the development of hypoxia in Omura Bay. 相似文献
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Takahiro Watanabe Toshio Nakamura Fumiko Watanabe Nara Takeshi Kakegawa Kazuho Horiuchi Ryoko Senda Takefumi Oda Mitsugu Nishimura Genki Inoue Matsumoto Takayoshi Kawai 《Quaternary International》2009,205(1-2):12
High-time resolution 14C dating of Lake Baikal sediment cores indicates negative and positive anomalies of calculated linear sedimentation rate (LSR; 1.1 and 35.6 cm/ka, respectively) during the period of climate transition from the last glacial to Holocene. The timing of the Lake Baikal apparent LSR anomalies is consistent with that of the changes in the atmospheric radiocarbon concentration (Δ14C) during Younger Dryas rapid cooling event. 14C dating of lipids in the Lake Baikal surface sediments revealed that the sources of sedimentary lipids were different in each basin. In the Northern Basin of Lake Baikal, the 14C age of total lipids from the surface sediment (4.0 14C ka) was found to be older than that of TOC (1.6 14C ka). By contrast, the 14C age of total lipids in the Southern Basin was younger than that of the TOC by ca. 0.7–3.0 ka.In the Lake Hovsgol sediment cores, ages of the main lithologic boundaries during the last glacial–interglacial transition were estimated based on new 14C data sets. TOC concentration in the cores started to rapidly increase at 13.8 ± 0.3 14C ka at the base of the basinwide finely laminated layer deposited during Bølling/Allerød. The base of the layer diatomaceous mud corresponds to the end of Younger Dryas event (10.6 ± 0.1 14C ka). 相似文献
9.
Yukinori Tani Fumiko Nara Yuko Soma Mitsuyuki Soma Nobuyasu Itoh Genki Inoue Matsumoto Atsushi Tanaka Takayoshi Kawai 《Quaternary International》2009,205(1-2):126
Past changes in phytoplankton assemblages in Lake Baikal over the last 4.5 Ma, both in population and composition, are inferred from the downcore profiles of the relatively stable chlorophyll derivatives steryl esters of pyropheophorbides a and b (steryl chlorine esters; SCEs) in the 0–200 m section of the BDP-98 drill core, supplemented by the data on biogenic silica (BSi) and total organic carbon (TOC) contents. SCEs-a and -b dominate among sedimentary chlorophyll derivatives in the BDP-98 sediments except for the upper few meters, indicating their high stability during diagenetic alteration of sediments. The depth (age) profiles of SCEs-a are consistent with BSi and TOC profiles and are interpreted as reflecting primary productivity of the lake in the past. Baikal proxies reveal close correlation with marine oxygen isotope records (MIS stratigraphy). These observations confirm that climate change in the northern hemisphere has been a primary factor controlling the total phytoplankton productivity in Lake Baikal during the last several million years.Among SCEs-a, C30 (dinostanol)-SCE-a, a marker of dinoflagellates was identified by GC–MS analysis. SCE-b, a marker of green algae, was identified by its UV–vis spectrum. The ratio of C30-SCE-a to total SCEs-a (TSCEs-a) was higher during 4.5–4.2 and 1.7–1.3 Ma, suggesting that dinoflagellates proliferated preferentially in those periods. The early Pleistocene maximum of this ratio corresponds to the broad minimum of diatom abundance previously suggested to have recorded a prolonged regional cooling. An abrupt increase in the SCE-b/TSCEs-a ratio was observed at 2.5–2.6 Ma, indicating that green algae containing chlorophyll b have proliferated in Lake Baikal during this period. This interval has also been suggested to contain evidence for a significant regional cooling based on minima of diatom abundance and BSi in sediments. The depth profile of C27Δ5 (cholesterol)-SCE-a relative to TSCEs-a showed a trend similar to that of BSi, suggesting that C27Δ5-SCE-a/TSCEs-a ratio is a potential marker of diatoms in Lake Baikal.Certain mismatches between the Lake Baikal profiles of biological indicators and the marine oxygen isotope records, as well as the slight temporal offsets between different Lake Baikal biological marker signals suggest that the regional component of climatic and/or lacustrine environmental changes also have played a role in determining the composition of the Lake Baikal Plio-Pleistocene phytoplankton assemblage. 相似文献
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Nara Somaratne Keith Smettem Jacqueline Frizenschaf 《Environmental Earth Sciences》2014,72(6):2141-2151
There is a broad variety of methods to estimate groundwater recharge, but tools to assess the reliability of particular methods are not available. This paper introduces three distinct criteria to assess the reliability of recharge: applicability of the method used, availability of reliable data, and spatial coverage. Weightings of each criterion are assigned using key attributes present to total attributes required under each criterion. A reliability assessment was applied to two point-recharge and two diffuse-recharge dominated groundwater basins in South Australia. We show that the use of groundwater age based on chlorofluorocarbon and the conventional chloride mass balance method gives unreliable estimates of recharge in karstic aquifers, primarily due to inappropriate assumptions concerning the nature of recharge in these systems. Among the methods evaluated, watertable fluctuation, numerical groundwater modelling, Darcy flow calculation and the water budget method are applied to both point and diffuse recharge dominant groundwater basins. The reliability of these methods depends primarily on the quality of data and spatial coverage of the basin. Once the reliability level is known, water resources planners and managers assess the level of risk to aquifers, the environment, and the socio-economic development required for sustainable management of groundwater. 相似文献