Radiochemical separation and determination of radium-228 in bottled mineral waters by low level gamma spectrometry and its committed effective dose     

Mihriban Şahin  Abdullah Dirican  Namık Kemal Şahin 《Environmental Earth Sciences》2017,76(23):795

?The gross beta and ²²⁸Ra radioactivity measurements in mineral waters were performed by proportional counter and gamma spectrometry, respectively, in this study. The natural mineral water samples were collected from various regions of Turkey for this study. Gross beta activities have been determined according to the United States Environmental Protection Agency standard method (EPA 900). In the case that the gross beta activity was determined to be greater than 1 Bq/L, then the ²²⁸Ra activity concentration in the related mineral water sample was specifically measured. ²²⁸Ra activity in mineral water samples was determined by high-purity germanium (HPGe) detector. The photopeak efficiencies were calculated by modeling the sample geometry and the detector in Canberra software LabSOCS. The gross beta activities in the eight of 32 bottled mineral water samples were greater than 1 Bq/L. ²²⁸Ra activity concentrations in bottled mineral waters were determined within 0.100–1.04 Bq/L. The committed effective doses were calculated for three different scenarios according to mineral water consumption rates.  相似文献   

A two‐step process for the reflooding of the Mediterranean after the Messinian Salinity Crisis     

François Bache  Speranta‐Maria Popescu  Marina Rabineau  Christian Gorini  Jean‐Pierre Suc  Georges Clauzon  Jean‐Louis Olivet  Jean‐Loup Rubino  Mihaela Carmen Melinte‐Dobrinescu  Ferran Estrada  Laurent Londeix  Rolando Armijo  Bertrand Meyer  Laurent Jolivet  Gwénaël Jouannic  Estelle Leroux  Daniel Aslanian  Antonio Tadeu Dos Reis  Ludovic Mocochain  Nikola Dumurdžanov  Ivan Zagorchev  Vesna Lesić  Dragana Tomić  M. Namık Çağatay  Jean‐Pierre Brun  Dimitrios Sokoutis  Istvan Csato  Gülsen Ucarkus  Ziyadin Çakır 《Basin Research》2012,24(2):125-153

The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re‐visited onshore data from Italy and Turkey that lead to a new concept of a two‐step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600–900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub‐basins led to diachronous events such as the so‐called ‘Lago Mare’.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two‐step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies.  相似文献   

Distribution of trace elements in subcellular fractions of three aquatic birds   总被引：1，自引：0，他引：1  

Nam DH  Anan Y  Ikemoto T  Kim EY  Tanabe S 《Marine pollution bulletin》2005,51(8-12):750-756

This study investigated the subcellular distribution of Cu, Zn, Cd and Ag in liver of mallard (Anas platyrhynchos), spot-billed duck (A. poecilorhyncha) and great cormorant (Phalacrocorax carbo) to better understand metal fractionation and dynamics in avian liver. Most of the total Cu, Zn, Cd and Ag were present in hepatocytosol, and their concentrations increased with total hepatic levels in all the three avian species. Copper, Zn and Cd in hepatocytosol were present mostly in metallothionein fractions (MTs), and Cu and Cd contents in this fraction were positively correlated with hepatocytosol levels in all the species. Silver was observed mostly in both high-molecular weight and MT fractions in hepatocytosol in mallard and great cormorant, whereas it was present in both low-molecular weight and MT fractions in spot-billed duck, suggesting that distribution of Ag in the hepatocytosol was species-specific. The elution profile of metals in MT fractions revealed six metallic peaks in mallard and spot-billed duck, and three peaks in great cormorant, implying the presence of multiple MT isoforms in the liver of these avian species. The present study demonstrated that MTs are closely associated with metal regulation, especially Cu and Cd, in these three aquatic birds.  相似文献   

Freshwater supply by Korean rivers to the East Sea during the last glacial maximum: a review and new evidence from the Korea Strait region     

Eunil?LeeEmail author  Seungil?Nam 《Geo-Marine Letters》2003,23(1):1-6

This study presents a review of extensive literature and reports new findings extracted from previously collected cores. Globally lowered sea level during the last glacial maximum (LGM) reduced the cross-sectional area in the Korea Strait, minimizing volume transport of the paleo-Tsushima Current and increasing freshwater input to the East Sea. The higher supply of freshwater played an important role in compositional changes of surface water in the sea, indicated by low sea surface salinity (down to about 20‰) and light d ¹⁸O of planktonic Foraminifera (lighter than 1‰) recorded in core sediments. The Korean fluvial systems (Nakdong and Seomjin rivers) emptying into the southeastern sea of Korea may have contributed substantially to freshwater supply to the surface layer of the LGM East Sea, although Chinese paleo-river (Huanghe and Yangtze rivers) waters, together with the paleo-Tsushima Current, also seem to have supplied some freshwater to the sea. The higher supply of river waters to the East Sea is strongly evidenced by the high amount of terrigenous material (quartz, feldspar and rock fragments) in core sediments. In addition, high magnetic susceptibility, high grain density, and high C/N ratios were documented in cores MB98PC-11 and 95PC-1. In contrast with earlier studies, we propose that Korean rivers played a more substantial role in supplying freshwater to the East Sea during the LGM than previously thought.  相似文献   

Study on coupling effects of ship motion and sloshing     

Y. Kim  B.W. Nam  D.W. Kim  Y.S. Kim 《Ocean Engineering》2007,34(16):2176-2187

This study considers the coupling effects of ship motion and sloshing. The linear ship motion is solved using an impulse-response-function (IRF) method, while the nonlinear sloshing flow is simulated using a finite-difference method. The IRF method requires the frequency-domain solution prior to conversion to time domain, but the computational effort is much less than that of direct time-domain approaches. The developed scheme is verified by comparing the motion RAOs between the frequency-domain solution and the solution obtained by the IRF method. Furthermore, a soft-spring concept and linear roll damping are implemented to predict more realistic motions of surge, sway, yaw, and roll. For the simulation of sloshing flow in liquid tanks, a physics-based numerical approach adopted by Kim [2001. Numerical simulation of sloshing flows with impact load. Applied Ocean Research 23, 53–62] and Kim et al. [2004. Numerical study on slosh-induced impact pressures on three-dimensional prismatic tanks. Applied Ocean Research 26, 213–226] is applied. In particular, the present method focuses on the simulation of the global motion of sloshing flow, ignoring some local phenomena. The sloshing-induced forces and moments are added to wave-excitation forces and moments, and then the corresponding body motion is obtained. The developed schemes are applied for two problems: the sway motion of a box-type barge with rectangular tanks and the roll motion of a modified S175 hull with rectangular anti-rolling tank. Motion RAOs are compared with existing results, showing fair agreement. It is found that the nonlinearity of sloshing flow is very important in coupling analysis. Due to the nonlinearity of sloshing flow, ship motion shows a strong sensitivity to wave slope.  相似文献   

Long-term and real-time monitoring system of the East/Japan sea     

Kuh Kim  Yun Bae Kim  Jong Jin Park  SungHyun Nam  Kyung-Ae Park  Kyung-Il Chang 《Ocean Science Journal》2005,40(1):25-44

Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-term current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.  相似文献   

Redox zonation for different groundwater flow paths during bank filtration: a case study at Liao River,Shenyang, northeastern China     

Xiaosi Su  Shuai Lu  Wenzhen Yuan  Nam Chil Woo  Zhenxue Dai  Weihong Dong  Shanghai Du  Xinyue Zhang 《Hydrogeology Journal》2018,26(5):1573-1589

The spatial and temporal distribution of redox zones in an aquifer is important when designing groundwater supply systems. Redox zonation can have direct or indirect control of the biological and chemical reactions and mobility of pollutants. In this study, redox conditions are characterized by interpreting the hydrogeological conditions and water chemistry in groundwater during bank infiltration at a site in Shenyang, northeast China. The relevant redox processes and zonal differences in a shallow flow path and deeper flow path at the field scale were revealed by monitoring the redox parameters and chemistry of groundwater near the Liao River. The results show obvious horizontal and vertical components of redox zones during bank filtration. Variations in the horizontal extent of the redox zone were controlled by the different permeabilities of the riverbed sediments and aquifer with depth. Horizontally, the redox zone was situated within 17 m of the riverbank for the shallow flow path and within 200 m for the deep flow path. The vertical extent of the redox zone was affected by precipitation and seasonal river floods and extended to 10 m below the surface. During bank filtration, iron and manganese oxides or hydroxides were reductively dissolved, and arsenic that was adsorbed onto the medium surface or coprecipitated is released into the groundwater. This leads to increased arsenic content in groundwater, which poses a serious threat to water supply security.  相似文献   

The Wuxie debris flows triggered by a record-breaking rainstorm on 10 June 2021 in Zhuji City,Zhejiang Province,China     

Wang  Fawu  Yan  Kongming  Nam  Kounghoon  Zhu  Guolong  Peng  Xingliang  Zhao  Zixin 《Landslides》2022,19(8):1913-1934

Landslides - Deep into the night of 9 June 2021, a high-intensity and short-duration rainstorm, the largest rainfall ever recorded in Zhuji, struck the entire city. The abrupt rainfall triggered...  相似文献   

Spectral Analysis based on Wavelet Transform Maxima: Identification of Multi-order Stratigraphic Boundaries and Cycles     

Song  Man Hyok  Won  Chang Dok  Chae  Chol Ho  Paek  Nam Il 《Mathematical Geosciences》2021,53(5):969-997

In sedimentology, stratigraphic sequences and cycles are ordered by time spans and physical scales, such as thickness, and bounded by discontinuities, including unconformities or flooding surfaces. Spectral analysis based on wavelet transform (WT) maxima is proposed and used as a quantitative tool to identify multi-order stratigraphic boundaries and cycles in well log data. The proposed spectral analysis is based on quantitative analysis on the center frequencies and resolutions of Gaussian wavelets in time and frequency, and uses a combination of the WT maxima based on both the first order Gaussian wavelet having a high time resolution and the seventh order Gaussian wavelet having a high frequency resolution. WT maxima spectra, which can characterize the evolution of WT maxima across scales and periods along WT maxima lines concerned with sequence boundaries, are used to detect dominant spectral peaks corresponding to the time-period domain WT maxima and to determine WT maxima spectral slopes. The WT maxima spectral slopes are helpful for discriminating sequence boundaries from intrasequence cyclic variations in well log data, and the time-period domain WT maxima are used to relate the detected boundaries to relevant cycles. The interval WT maxima spectra and the stationary index, related to the WT maxima spectra, are introduced as indicators that can be used for the hierarchical ordering of the boundaries and cycles. Application of the proposed method to well log data shows that the suggested method is efficient in identifying multi-order sequences that relate well to the Milankovitch cycles.

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Molecular characterization and morphology of the photosynthetic dinoflagellate Bysmatrum caponii from two solar saltons in western Korea     

Hae Jin Jeong  Se Hyeon Jang  Nam Seon Kang  Yeong Du Yoo  Min Jeong Kim  Kyung Ha Lee  Eun Young Yoon  éric Potvin  Yeong Jong Hwang  Jong Im Kim  Kyeong Ah Seong 《Ocean Science Journal》2012,47(1):1-18

Species belonging to the genus Bysmatrum are peridinoid, thecate, photosynthetic dinoflagellates. The plate formula of Bysmatrum spp., arranged in a Kofoidian series, is almost identical to that of Scrippsiella spp. Bysmatrum spp., which were originally classified as Scrippsiella spp., but were transferred to the genus Bysmatrum spp. because of separation of the intercalary plates 2a and 3a by plate 3??. Whether this transfer from Scrippsiella spp. to Bysmatrum spp. is reasonable should be genetically confirmed. Dinoflagellates were isolated from 2 solar saltons located in western Korea in 2009?C2010 and 3 clonal cultures from Sooseong solar saltons and 2 clonal cultures from Garolim solar saltons were successfully established. All of these dinoflagellates were identified as Bysmatrum caponii based on morphology analysis by light and electron microscopy. The plates of all Korean strains of B. caponii were arranged in a Kofoidian series of Po, X, 4??, 3a, 7??, 6c, 4s, 5?, 0 (p), and 24??. When properly aligned, the ribosomal DNA (rDNA) sequences of the 3 Sooseong strains of B. caponii were identical, as were those of the 2 Garolim strains. Furthermore, the sequences of the 3 Sooseong strains were 0.01% different from those of the Garolim strains. However, the sequences of SSU rDNA of these Korean B. caponii strains were 9% different from that of Bysmatrum subsalsum and > 10% from that of any other dinoflagellate thus far reported. In the phylogenetic trees generated using SSU and LSU rDNA sequences, these Korean B. caponii strains formed a clade with B. subsalsum which was clearly divergent from the Scrippsiella clade. However, this Bysmatrum clade was phylogenetically close to the Protoperidinium and/or Peridinium clades. The results of the present study suggest that Bysmatrum spp. are markedly different genetically from Scrippsiella spp..  相似文献