Climate-related variations in crustal trace elements in Dome C (East Antarctica) ice during the past 672 kyr     

Alexandrine Marteel  Vania Gaspari  Claude F. Boutron  Carlo Barbante  Paolo Gabrielli  Paolo Cescon  Giulio Cozzi  Christophe P. Ferrari  Aurélien Dommergue  Kevin Rosman  Sungmin Hong  Soon Do Hur 《Climatic change》2009,92(1-2):191-211

Cr, Fe, Rb, Ba and U were determined by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) in various sections of the 3,270 m deep ice core recently drilled at Dome C on the high East Antarctic plateau as part of the EPICA program. The sections were dated from 263 kyr bp (depth of 2,368 m) to 672 kyr bp (depth of 3,062 m). When combined with the data previously obtained by Gabrielli and co-workers for the upper 2,193 m of the core, it gives a detailed record for these elements during a 672-kyr period from the Holocene back to Marine Isotopic Stage (MIS) 16.2. Concentrations and fallout fluxes of all elements are found to be highly variable with low values during the successive interglacial periods and much higher values during the coldest periods of the last eight climatic cycles. Crustal enrichment factors indicates that rock and soil dust is the dominant source for Fe, Rb, Ba and U whatever the period and for Cr during the glacial maxima. The relationship between Cr, Fe, Rb, Ba and U concentrations and the deuterium content of the ice appears to be similar before and after the Mid-Brunhes Event (MBE, around 430 kyr bp). Mean concentration values observed during the successive interglacials from the Holocene to MIS 15.5 appear to vary from one interglacial to another at least for part of the elements. Concentrations observed during the successive glacial maxima suggest a decreasing trend from the most recent glacial maxima (MIS 2.2 and 4.2) to the oldest glacial maxima such as MIS 14.2, 14.4 and 16.2, which could be linked with changes in the size distribution of dust particles transported from mid-latitude areas to the East Antarctic ice cap.  相似文献   

Experimental Study on Flow past A Rotationally Oscillating Cylinder     

GAO Yang-yang  YIN Chang-shan  YANG Kang  ZHAO Xi-zeng  TAN Soon Keat 《海洋工程》2017,31(4):495-503

A series of experiments was carried out to study the flow behaviour behind a rotationally oscillating cylinder at a low Reynolds number (Re=300) placed in a recirculation water channel. A stepper motor was used to rotate the cylinder clockwise- and- counterclockwise about its longitudinal axis at selected frequencies. The particle image velocimetry (PIV) technique was used to capture the flow field behind a rotationally oscillating cylinder. Instantaneous and time-averaged flow fields such as the vorticity contours, streamline topologies and velocity distributions were analyzed. The effects of four rotation angle and frequency ratios F_r (F_r=f_n/f_v, the ratio of the forcing frequency f_n to the natural vortex shedding frequency f_v) on the wake in the lee of a rotationally oscillating cylinder were also examined. The significant wake modification was observed when the cylinder undergoes clockwise-and-counterclockwise motion with amplitude of π, especially in the range of 0.6≤F_r≤1.0.  相似文献   

Erratum to: Effects of environmental and biological conditions on the recruitment and growth of the Manila Clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> on the West Coast of Korea     

Sang Lyeol Kim  Soon Hyun Kwon  Hyung-Gon Lee  Ok Hwan Yu 《Ocean Science Journal》2017,52(1):165-165

  相似文献   

Variations in surface activity of the sun and solar-type stars     

W. H. Soon  S. L. Baliunas  Q. Zhang 《Solar physics》1994,154(2):385-391

Twenty-five-year records of relative Caii H and K emission fluxes of lower Main-Sequence stars have been measured at Mount Wilson Observatory and reveal surface activity in most of the older G- and K-type dwarf stars that is similar to the aperiodical activity cycle of the contemporary Sun (i.e., the cyclic and the occasional episode of reduced activity in the past few centuries). We find an inverse relationship between the amplitude of the activity cycle and the length of the cycle for the ensemble of those solar-type stars. We also find a similar relationship using the 250-year sunspot record (Cycles 1 to 21). The similarity between the two inverse relationships for the solar-type stars observed for 25 years and the Sun for a longer interval of time may suggest one common underlying physical mechanism that is responsible for the variations in surface activity ranging from decades to centuries.Also at Center for Excellence in Information Systems at Tennessee State University.  相似文献   

TBT toxicity on the marine microalga Nannochloropsis oculata   总被引：1，自引：0，他引：1  

Sidharthan M  Young KS  Woul LH  Soon PK  Shin HW 《Marine pollution bulletin》2002,45(1-12):177-180

Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l⁻¹) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC₅₀ (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed.  相似文献   

Sr–Nd–Pb isotopic compositions of the Kovdor phoscorite–carbonatite complex, Kola Peninsula, NW Russia     

Mi Jung Lee  Jong Ik Lee  Soon Do Hur  Yeadong Kim  Jacques Moutte  Elena Balaganskaya   《Lithos》2006,91(1-4):250-261

The Sr, Nd and Pb isotopic compositions for the Kovdor phoscorite–carbonatite complex (PCC), Kola Peninsula, NW Russia, have been determined to characterize the mantle sources involved and to evaluate the relative contributions of a plume and subcontinental lithospheric mantle in the formation of the complex. The Kovdor PCC is a part of the Kovdor ultramafic–alkaline–carbonatite massif, and consists of six intrusions. The initial isotopic ratios of the analyzed samples, calculated at 380 Ma, display limited variations: ε_Nd, + 2.0 to + 4.7; ⁸⁷Sr/⁸⁶Sr, 0.70319 to 0.70361 (ε_Sr, − 12.2 to − 6.2); ²⁰⁶Pb/²⁰⁴Pb, 18.38 to 18.74; ²⁰⁷Pb/²⁰⁴Pb, 15.45 to 15.50; ²⁰⁸Pb/²⁰⁴Pb, 37.98 to 39.28. The Nd and Sr isotope data of the Kovdor PCC generally fit the patterns of the other phoscorites and carbonatites from the Kola Alkaline Province (KAP), but some data are slightly shifted from the mixing line defined as the Kola Carbonatite Line, having more radiogenic ⁸⁷Sr/⁸⁶Sr ratios. However, the less radiogenic Nd isotopic compositions and negative Δ7/4 values of Pb isotopes of the analyzed samples exclude crustal contamination, but imply the involvement of a metasomatized lithospheric mantle source. Isotopic variations indicate mixing of at least three distinct mantle components: FOZO-like primitive plume component, EMI-like enriched component and DMM-like depleted component. The isotopic nature of the EMI- and DMM-like mantle component observed in the Kovdor samples is considered to be inherited from metasomatized subcontinental lithospheric mantle. This supports the previous models invoking plume–lithosphere interaction to explain the origin of the Devonian alkaline carbonatite magmatism in the KAP.  相似文献   

HEAVY METAL POLLUTION IN SURFACE SEDIMENTS COLLECTED FROM DRAINAGES RECEIVING DIFFERENT ANTHROPOGENIC SOURCES FROM PENINSULAR MALAYSIA     

Chee Kong Yap  Bin Huan Pang  Yoong Inn Hoo  Soon Guan Tan 《湿地科学》2007,5(2):97-104

Surface drainage sediments were collected, between January and April in 2005, from 6 sampling sites in Peninsular Malaysia suspected to have received different anthropogenic sources. These drainages included sites near a petrochemical plant, an electronic factory, a metal factory and 2 townships in addition to a relatively unpolluted site (a reference site). Based on the aqua-regia method, the metal concentrations for all the sampling sites except for the agricultural site (reference site) at Sg. Benut were between 60.92-1 019 μg/g dry weight for copper (Cu), 65.32-1 266.6μg/g dry weight for plumbum (Pb), 1.46-15.93 μg/g dry weight for cadmium (Cd), 330.10-484.14 μg/g dry weight for zinc (Zn) and 47.03-120.90 μg/g dry weight for nickel (Ni). All of these ranges were significantly (p< 0.05) higher than those (Cu: 8.77 μg/g; Pb: 57.42 μg/g; Cd: 0.96 μg/g; Zn: 68.21 μg/g; and Ni: 17.87 μg/g) of the reference site at Sg. Benut that only received agricultural disposal. The concentrations for the 5 metals from all the sites (except for the reference site) were higher than the Sediment Quality Values for Hong Kong by Chapman et al (1999) for the 5 metals. Based on the sequential extraction technique, 3 geochemical fractions [easily, freely leachable and exchangeable (EFLE), acid-reducible and oxidisable-organic] were also useful in identifying these polluted sites. The elevated metal concentrations found in the sediments might be related to point sources of industrial effluent and urban waste. Hence, the results emphasized the necessity for the treatment of effluents into this drainage area. As part of the effort to control illegal discharges and dumping into drainages, public awareness should be enhanced.  相似文献   

Modification of the Natural Slake Test and Assessment of Slaking Behavior of a Shale from Malaysia Under Rainfall     

Lai  Teck Yew  Loo  Vera Hui  Wong  Vun Ket  Wong  Kwong Soon 《Geotechnical and Geological Engineering》2022,40(6):3169-3190

Geotechnical and Geological Engineering - The durability of clay-bearing rocks has been a concern to the construction industry. Extensive research have been conducted to determine the durability of...  相似文献   

Evolution of morphological features of CMEs deduced from catastrophe model of solar eruptions     

J. Lin  W. Soon 《New Astronomy》2004,9(8):611-628

We describe the evolution of morphological features of the magnetic configuration of CME according to the catastrophe model developed previously. For the parameters chosen for the present work, roughly half of the total mass is nominally contained in the initial flux rope, while the remaining plasma is brought by magnetic reconnection from the corona into the current sheet and from there into the CME bubble. The physical attributes of the difference in the observable features between CME bubble and flare loop system were studied. We tentatively identified distinguishable evolutionary features like the outer shell, the expanding bubble and the flux rope with the leading edge, void and core of the 3-component CME structure. The role of magnetic reconnection is discussed as a possible mechanism for the heating of the prominence material during eruptions. Several aspects of this explanation that need improvement are outlined.  相似文献   

Estimating historic lake stages from one‐time snapshot,the Shuttle Radar Topography Mission of 2000     

Kon Joon Bhang  Frank W. Schwartz  Seok‐Soon Park 《水文研究》2010,24(13):1834-1843

Lake studies play an important role in water management, ecology and other environmental issues. Monitoring lake stages is typically the first step on the lake studies. However, for the Prairie Pothole Region (PPR) of North America with millions of small lakes and potholes, onsite measurements for lake stages are almost impossible with the conventional gage stations due to the limited accessibility to lakes and the requirement of economical and human resources. To overcome this limitation, we employed the remote‐sensing approach to extract lake stages in PPR for bulk processing. To estimate lake stages, several image‐processing techniques were used with the Shuttle Radar Topography Mission (SRTM) data in January, 2000, a one‐time snapshot useful in historic lake level reconstruction. In this research, image processing techniques, for example, averaging, Fast Fourier Transform (FFT), Lee‐Sigma filtering were applied and masking with Canny Edge Detector (CED) and semi‐automated contouring were developed for lake stage estimation. In terms of simplicity, averaging might be useful if 1·5 m of the local bias for the study area in stage estimates. However, the FFT and Lee‐Sigma methods were slightly better than averaging. Masking with CED and semi‐automated contouring provided outstanding accuracy in the estimation. The masking and contouring methods provided ± 0·5 m of stage differences for relatively large lakes greater than 10 km² when compared with stage reading in spite of their calculation complexities and was shown as the best approaches among implemented methods in this study. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献