Perylene dominance in sediments from a subtropical high mountain lake     

Cheng-Wei Fan  J. ShiueCheng-Yi Wu  Cheng-Yu Wu 《Organic Geochemistry》2011,42(1):116-119

Perylene formation in sediments of water bodies has been a topic of continual discussion and debate. We report the concentration and age (ca. 660 yr) profiles of perylene and other polycyclic aromatic hydrocarbons (PAHs) in a sediment core from Emerald Peak Lake, the largest high mountain lake in Taiwan. Perylene is dominant at all depths of the sediment (ranging from 60% to 98% of total PAHs), a feature not commonly found in other sediments. The concentration profile of perylene with sediment age fits a first order kinetic model, which might be an indication of a steady sedimentary environment.  相似文献   

Description of the larval stage of Drusus mixtus (Pictet, 1834) (Trichoptera: Limnephilidae: Drusinae) with notes on its ecology and zoogeography     

Johann Waringer  Wolfram Graf  Thomas Pitsch  Steffen U. Pauls  Ana Previši?  Mladen Ku?ini? 《Limnologica》2011,41(3):249-255

In the Swiss Jura adults of Drusus mixtus and unknown Drusinae larvae which could not be identified with existing keys were sampled. Based on ripe pupae, the unknown larvae were identified as D. mixtus. The association was confirmed by specimen rearing in aquaria.Based on morphology, larvae of D. mixtus key out together with Drusus croaticus in existing keys. D. mixtus is separated from the latter species by the shape of the anteromedian metanotal sclerites which are broadly triangular, whereas in D. croaticus the sclerites are almost parallel-sided, resembling a stretched rectangle. In addition, the two species are geographically well separated: D. croaticus is restricted to the confines of Croatia and Slovenia, whereas D. mixtus is only present in Switzerland and eastern France. With this present paper, all Central European Drusinae species except Drusus chapmani McL, 1901, (France, Switzerland) and D. noricus Malicky, 1981, an endemic from the Saualpe (Carinthia, Austria), are known in the larval stage.  相似文献   

Geomagnetic anomaly at Lunping before the 1999 Chi-Chi earthquake (M w  = 7.6) in Taiwan     

Chen  Kuang-Jung  Chiu  Bonbbon  Wang  Jee-Shiang  Lee  Cheng-Yu  Lin  Cheng-Horng  Chao  Kevin 《Natural Hazards》2011,58(3):1233-1252

A strong earthquake with a magnitude of 7.6 (M _L  = 7.3) occurred on September 21, 1999, in central Taiwan. In order to discern any potential precursors before this earthquake, geomagnetic data at Lunping (LNP), Taiwan, Geomagnetic Observatory situated 100 km from the epicenter are examined using two methods, i.e., the traditional induction arrows and complex demodulation. Our results show that the remarkable temporal variation of real induction arrows appear to be strong prior to the great earthquake over the previous 24 months. After the great earthquake, the magnitudes of induction arrows decreased to the normal (mean of 8 years) levels. In other words, the direction of real induction arrows of the periods 30 and 20 min rotated 85° and 40° anticlockwise, respectively, before the Chi-Chi earthquake and returned to mean direction of last 10 years after the earthquake. A horizontal source field model using the finite difference method for 3-D shows that the variation of the real induction arrows might be ascribed to the conductivity variation body, which is 5 km buried at the epicenter area of the Chi-Chi earthquake, changing its conductivity from 0.002S/m to 0.06 S/m. The ratios of modulus (demodulated by using the complex demodulation method) over a period 12, and 8 h relative to the period of 24 h reveal a remarkable change that appeared 4–5 months prior to this strong earthquake. They increased gradually from the beginning of 1999 to August 1999 and decreased again to a (8 years) mean level after the strong earthquake occurrence. We consider that the variation of the induction arrow might be ascribed to the conductivity anomaly, which is buried 5 km at the south-east side of LNP with a conductivity change of 0.06 S/m. We propose that this elevation might be related to the preparation process of the great earthquake.  相似文献   

Geochronology and stable isotope signature of alteration related to hydrothermal magnetite ores in Central Anatolia,Turkey     

Robert Marschik  Richard Spikings  Ilkay Kuşcu 《Mineralium Deposita》2008,43(1):111-124

Hydrothermal iron ores at Divri?i, east Central Anatolia, are contained in two orebodies, the magnetite-rich A-kafa and the limonitic B-kafa (resources of 133.8 Mt with 56% Fe and 0.5% Cu). The magnetite ores are hosted in serpentinites of the Divri?i ophiolite at the contact with plutons of the Murmano complex. Hydrothermal biotite from the Divri?i A-kafa yield identical weighted mean plateau ages of 73.75?±?0.62 and 74.34?±?0.83 Ma (2σ). This biotite represents a late alteration phase, and its age is a minimum age for the magnetite ore. Similar magnetite ores occur at Hasançelebi and Karakuz, south of Divri?i. There, the iron ores are hosted in volcanic or subvolcanic rocks, respectively, and are associated with a voluminous scapolite ± amphibole ± biotite alteration. At Hasançelebi, biotite is intergrown with parts of the magnetite, and both minerals formed coevally. The weighted mean plateau ages of hydrothermal biotite of 73.43?±?0.41 and 74.92?±?0.39 Ma (2σ), therefore, represent mineralization ages. Hydrothermal biotite from a vein cutting the scapolitized host rocks south of the Hasançelebi prospect has a weighted mean plateau age of 73.12?±?0.75 Ma (2σ). This age, together with the two biotite ages from the Hasançelebi ores, constrains the minimum age of the volcanic host rocks, syenitic porphyry dikes therein, and the scapolite alteration affecting both rock types. Pyrite and calcite also represent late hydrothermal stages in all of these magnetite deposits. The sulfur isotope composition of pyrite between 11.5 and 17.4‰ δ³⁴S_(VCDT) points towards a non-magmatic sulfur source of probably evaporitic origin. Calcite from the Divri?i deposit has δ¹⁸O_(VSMOV) values between +15.1 and +26.5‰ and δ¹³C_(VPDB) values between ?2.5 and +2.0‰, which are compatible with an involvement of modified marine evaporitic fluids during the late hydrothermal stages, assuming calcite formation temperatures of about 300°C. The presence of evaporite-derived brines also during the early stages is corroborated by the pre-magnetite scapolite alteration at Divri?i, and Hasançelebi-Karakuz, and with paleogeographic and paleoclimatic reconstructions. The data are compatible with a previously proposed genetic model for the Divri?i deposit in which hydrothermal fluids leach and redistribute iron from ophiolitic rocks concomitant with the cooling of the nearby plutons.  相似文献   

The mineralogy,geochemistry, and suitability for ceramic applications of Akharım (Afyonkarahisar,W Turkey) kaolinitic clay     

M. Kuşcu  Ahmet Yıldız 《Arabian Journal of Geosciences》2016,9(7):510

Kaolinitic clays associated with sedimentary rocks cover widespread in the Yeniköy formation from the Akhar?m district, (Afyonkarahisar, W Anatolia). Due to the proximity to the ceramic industry areas such as Kütahya and U?ak Province of Turkey, the clays in the Akhar?m district have been intensively exploited for the last few years. The Akhar?m kaolinitic clays were hosted by Middle-Upper Miocene-aged Yeniköy formation and divided into two parts as northeastern and southwestern via normal fault. The alteration degree increases from lower levels to surface in the NE part of deposit. Besides layered structure in their N70° W/30° SW direction and gray-beige, yellowish brown colored in SW part. This study focused on mineralogy, geochemistry, and ceramic properties of kaolinitic clays. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, chemical, physical, and mechanical tests were conducted on studied samples from the wall of clay quarry. Akhar?m clay deposits consist of mainly kaolinite and quartz. Additionally, they include smectite, biotite, feldspar, jarosite, calcite, and hematite minerals. Akhar?m clays are characterized with their moderate plasticity (PL = 17.07–24.09), low water absorption (3.64–9.53 wt.%), low linear shrinkage (8.08–15.55 wt.%), high bending strength (17.72–32.69 N/mm²), and ideal lightness values (L* = 46.50–82.74) and color values (a* = 4.71–29.87; b* = 14.67–28.72). These properties vary related with mineralogical and geochemical features of Akhar?m clays. In conclusion, Akhar?m clays have desired specifications for floor and wall t to their mineralogical, geochemical, and ceramic properties.  相似文献   

Undrained Shear Strength in Cohesive Soils Estimated by Directional Modes of In-Situ Shear Wave Velocity     

Sung-Woo Moon  Taeseo Ku 《Geotechnical and Geological Engineering》2018,36(5):2851-2868

The estimated undrained shear strength (s_u) is often not a unique value because it can be evaluated by various test types and/or procedures, such as different failure modes, shear strain rates, and boundary conditions. This study explores (1) the relationship between reference undrained shear strength and in situ shear wave velocity in terms of the effective overburden stress, and (2) the independent relationships to evaluate the undrained shear strength with special consideration of different directional and polarization modes (VH, HV, HH shear waves), which has not been reported. This evaluation is done via a worldwide database compiled from 43 well-documented geotechnical test sites associated with soft ground. Finally, new correlation models are proposed to estimate the undrained shear strength based on the in situ shear wave velocity as well as the plasticity index or the overconsolidation ratio. The application of the shear wave velocity–undrained shear strength relation is illustrated through two independent case studies. The proposed relationships are expected to contribute to reasonable estimates of undrained shear strength as well as offer practical guidance on even extrapolation beyond the data that is available to geotechnical engineers.  相似文献   

M. Fytikas, G. E. Vougioukalakis (eds): The South Aegean active volcanic arc: present knowledge and future perspectives
Elsevier, 2005. Developments in Volcanology, v.7. Hardcover, 398 pages, ISBN 10: 0-444-52046-5, ISBN 13: 978-0-444-52046-3, USD 195.00     

Gonca Gen?alio?lu Ku?cu 《Bulletin of Volcanology》2012,74(1):303-304

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Inter-decadal Variability in Phytoplankton Community in the Middle Adriatic (Kaštela Bay) in Relation to the North Atlantic Oscillation     

Živana Ninčević Gladan  Ivona Marasović  Branka Grbec  Sanda Skejić  Mia Bužančić  Grozdan Kušpilić  Slavica Matijević  Frano Matić 《Estuaries and Coasts》2010,33(2):376-383

Evaluation of a 45-year data set of primary production (PP), a 30-year data set of phytoplankton biomass, and a 51-year data set of species composition shows an increase of phytoplankton biomass and abundance in the period from the mid-1980s to the mid-1990s. Phytoplankton biomass showed bimodal seasonal cycles, with winter and spring maxima, which did not change over the past 30 years. Diatoms were the most abundant functional group and they prevailed during the colder part of the year while the dinoflagellate contribution to the phytoplankton community increased in the warmer period from May to August. Diatoms showed a significant negative correlation with sea surface temperature (SST), while dinoflagellates were positively correlated with SST. An increase of phytoplankton abundance, particularly dinoflagellate, in the period from the mid-1980s to the mid-1990s coincided with years characterized by a high North Atlantic Oscillation (NAO) index. Primary production and chlorophyll a concentration in the spring period were negatively correlated with the NAO winter (DJFM) index, probably caused by increased precipitation associated with a low or negative NAO index. PP in winter during the mixing period was positively related to the NAO winter index associated with higher temperatures and dry conditions which brought more clear days and increased input of solar radiation.  相似文献   

Framework for assessing probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time     

Chih-Chieh Lu  Jin-Hung Hwang  C. Hsein Juang  Chih-Sheng Ku  Zhe Luo 《Engineering Geology》2009,108(1-2):24-35

This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of a_max and M_w). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted.  相似文献   

Observations of pulsating X-ray binaries 4U0900-40 and 4U1223-62     

W. H. -M. Ku  R. S. Wolff 《Astrophysics and Space Science》1979,62(2):439-449

A rocket observation of two pulsating X-ray binaries, 4U0900-40 and 4U1223-62, found no evidence for periodic or quasiperiodic behavior on time scales down to 2 ms. Evidence for complex high-energy spectral features and intrapulse variability is presented for 4U0900-40.  相似文献