Geosciences Journal

Published by Springer Verlag
Online ISSN: 1598-7477
Publications
Article
Recently, extensive research on soil and groundwater remediation has demonstrated surfactant (surface active agents) flushing to be a viable alternative for improving the efficiency of pump-and-treat remediation. Column tests were carried out to examine the effect of surfactant solution conditions on surfactant-enhanced remediation of soil columns contaminated by 1,2,4-trichlorobenzene (TCB). An Iowa Fruitfield soil was used for this study and sodium diphenyl oxide disulfonate (DOSL) that is an anionic surfactant was selected in this research. The conditioned parameters of the surfactant solution for the column tests were concentration, pH, temperature and flow rate. The test results revealed that an optimum condition was achieved for 4% (v/v) of concentration, pH 10, 20°C of temperature and 4 mL/min of flow rate, respectively. The removal of 98% of TCB was obtained with combination of optimal conditions of surfactant solution with NaCl. This was a marked improvement and removal efficiency increased by 4–17% compared to that with unadjusted (not optimum) conditions. The optimum range of these parameters may be useful for surfactant-based remediation in soil contaminated by TCB.
 
Article
Ontogenetic change in δ18O values of the investigatedNautilus pompilius Linne shell in the Philippines (Tagnan, Panglao Islands, Bohol Island area) confirms data, in whichNautilus in the wild shows a marked increase in oxygen isotopic composition between embryonic and post-embryonic stages. The increase in δ18O in post-embryonic septa reflects a migration into colder, deeper (about 300 m) waters. Judging from the isotopic composition of aboral and adoral parts of the last septum, the amplitude of the short term vertical migration for the investigated sample seems to be about 70 m. Relative fluctuation in δ13C values for the livingNautilus, as well as living brachiopods, might be connected with annual cycles of the phytoplankton development. The negative δ13C excurse (−2.5‰) fixed in the septa 9 of the investigatedNautilus pompilius shell seems to be connected with a weakening of phytoplankton bioproductivity related to low solar activity. It is suggested that ammonoids, like livingNautilus spent the most part of their lives near the sea-floor but unlikeNautilus and late Cretaceous belemnites they did not experience, apparently, significant short-term vertical migration.
 
Article
The well-defined pollen record in massive marine clay deposits from the subaqueous Changjiang (Yangtze River) delta reveals changes in vegetation and inferred climate during the last about 1600 years. Climatic periods inferred from the pollen record include (1) a basal cool/dry period (AD 385–910), (2) a relatively warm/wet conditions comparable to Medieval Warm Period (AD 910-1085) with a strengthen summer monsoon, (3) a relatively cool and wet conditions possibly corresponding to Little Ice Age (LIA; AD 1085–1815) with a weaken summer monsoon, and finally (4) the present warm period, since AD 1815. The pollen aridity index based on variations in humidity suggests that three subperiods within the LIA can be identified: wet LIA-1 (AD 1085-1170), dry LIA-2 (AD 1170–1330), and wet LIA-3 (AD 1330–1815).
 
Article
Two sites (Sites 1150 and 1151) located in the landward deep-sea terrace of the Japan Trench were drilled during the Ocean Drilling Program (ODP) Leg 186. Site 1150 is seismically active, whereas Site 1151, aseismic. Measurements of sediment physical properties were made on both whole-round core and split-core sections. Bulk density is relatively uniform with similar variation with depth, although its absolute values are slightly different. It is most likely attributable to coring disturbance. Magnetic susceptibility is characterized by the highest value at the lithologic unit I. Depth variation of water content and porosity shows gradual decreasing pattern, except for lithologic unit I, similar to that of natural Gamma radiation. The abnormal characteristics of unit I are likely related to the under-consolidation caused by rapid deposition (100–200 m/myr) as well as impermeable nature of the sediment preventing dewatering. Grain density is higher in the unit I, but below which is relatively constant with depth. P-wave velocity gradually increases from 1500 to 2000 m/s with depth, caused by sediment compaction and/or consolidation. Sediment physical properties of both sites are very similar, although p-wave velocity is slightly higher (≈20 m/s on the average) at Site 1151. This indicates that sediment source, mineral composition and sediment diagenesis are not significantly different at both sites, implying that seismic activities such as earthquake do not likely cause marked changes of sediment physical properties.
 
Article
The systematics, stratigraphic distribution and geographic distribution of two widely distributed agnostoid species from the Furongian Series of the Cambrian are reviewed. The speciesAgnostotes orientalis (Kobayashi, 1935) andLotagnostus americanus (Billings, 1860) have been described from around the world under a variety of species and subspecies names, and have been assigned to a variety of genera. Nomenclatural problems have hindered to some extent a full under standing of the value of these two forms for intercontinental correlation. Both species have relatively narrow stratigraphic ranges and intercontinental distributions in open-shelf lithofacies. These conditions make these species excellent candidates for defining the bases of stage boundaries within the Furongian Series.
 
Article
The Upper Cambrian conodont taxa of the Dasytodontus Lineage is particularly useful to divide strata near Cambrian-Ordovician boundary. This lineage known only in Korea, China and Australia include many coniform paraconodonts and euconodonts with granulose, spinose or nodose ornaments, comprising Granatodontus Chen et Gong, 1986. The generic and specific concepts of Granatodontus are reviewed herein, with comments on its evolution, paleoecology and geographic distribution. Two new species are erected: Granatodontus asymmetrica sp. nov. and Granatodontus multicorrugata sp. nov.
 
Article
The crustal velocity structure is one of the fundamental and important subjects for seismology. The receiver function analysis technique is applied to the data from six broadband stations (HKU, JSB, MGB, NPR, SND, and TJN) in the Okcheon Fold Belt of Korea. The genetic algorithm that is independent of the initial model is adopted as the inversion method. The surfacewave dispersion data are used as constraints in the receiver function inversion. Among these stations, the receiver function analyses on the velocity structures beneath stations JSB, MGB, and SND have not been carried out before. Since recent large teleseismic earthquake data of magnitudes larger than 6.5 are included in the analyses, the velocity structures found in the present work are expected to be more reliable than those by the previous independent works. The characteristics of crustal velocity structures in the Okcheon Fold Belt are revealed. The crustal thickness in the Okcheon Fold Belt is estimated to be 32–34 km. The Moho depths are 32, 34, 32, 32–34, 32, and 32 km beneath stations HKU, JSB, MGB, NPR, SND, and TJN, respectively. These results are similar to those found in the previous independent works. The low velocity layers around the depth of 10 km are also found. Geological interpretation or correlations are, however, skipped since they are not always distinctive. Midcrustal velocity discontinuities at the 18-km depth are found beneath stations NPR and TJN although the former is only distinctive. Those at the 22-km depth are also found beneath stations HKU and SND. The crustal velocity structures estimated in this study will be able to offer fundamental information to other geologists, and the geological and tectonic interpretation of the velocity structures is expected. Key wordscrustal velocity structure-Okcheon Fold Belt-receiver function-surface-wave dispersion-genetic algorithm
 
Article
A computer program has been developed to evaluate electromagnetic (EM) responses for a one-dimensional (1D) model with multiple source and receiver dipoles that are finite in length. Using the 1D code, we conducted sensitivity analysis of marine controlled-source EM methods to a gas-hydrate layer in the shallow section. In this study we used a normalized amplitude and amplitude difference of EM fields simultaneously in determining the detection capability of the hydrate layer. The field amplitude must be normalized by the one for the corresponding background model without the hydrate layer. The normalized amplitude can be numerically large, but if the field amplitude is smaller than the threshold, it would be misleading and therefore is useless. From these numerical experiments, we found that there are plenty of useful offset ranges and frequencies where amplitude difference is large enough to detect the target layer. Furthermore, an effect of air waves is almost absent in amplitude difference. Key wordsmarine CSEM–gas hydrate–normalized amplitude–amplitude difference–air wave
 
(a) A simplified tectonic province map of East Asia. Stars denote two outcrop locations of ca. 2.5 Ga grey gneisses of Zhao et al. (2006). Abbreviations: GM, Gyeonggi massif; HS, Hongseong; IB, Imjingang belt; NCB, North China block (or craton); NM, Nangrim massif; OB, Ogcheon belt; SCB, South China block (or craton); YM, Yeongman massif; and (b) A geological map of Daeijak and Soijak islands showing the distribution of migmatitic gneiss, tonalitic gneiss and metasedimentary rocks. Star denotes the location of the analyzed tonalitic migmatite DE01.
SHRIMP U-Pb isotopic data of the analyzed zircons
Outcrop photograph of tonalitic migmatite and mafic xenolith. (a) Dioritic amphibolite xenolith in tonalitic migmatite. (b) Tonalitic, hornblende-biotite gneiss. The circle shows the location of the analyzed sample DE01. Black pen for scale is 14 cm.
Cathodoluminescence (CL) images of representative zircon grains separated from DE01. Zircon grains show distinct CL zoning patterns characterized by magmatic oscillatory-zoned cores mantled by structreless or bright CL rims. The 2 0 7 Pb/ 2 0 6
Article
We discovered the oldest rock in South Korea, and dated this migmatite using a Sensitive High-Resolution Ion Micro-probe (SHRIMP). Zircon grains from a tonalitic migmatite, Daeijak Island, western Gyeonggi massif, are distinctly zoned and commonly characterized by oscillatory-zoned cores and structureless rims. The U-Pb zircon ages estimated from six spot analyses of the rims in five grains define a concordant age group with the weighted mean 207Pb/206Pb age of 2508 ± 18 Ma, interpreted as the age of migmatization. On the other hand, the cores yield an older 207Pb/206Pb age of ca. 2.58 Ga, interpreted as the crystallization age of tonalitic protolith. These results demonstrate not only the presence of Neoarchean granitoids but also high-grade migmatitic metamorphism at ca. 2.51 Ga in the Gyeonggi massif, which are correlative with those reported from the North China craton.
 
Article
In order to reveal the perspective of velocity structure in the southern part of the Korean peninsula, a seismic experiment was carried out along a WNW-ESE profile of 294-km length in December, 2002. In 100-m deep drill-holes, seismic explosives of 1000 and 500 kg were detonated on the west coast and near the center of the profile, respectively. The seismic signals were detected by 198 portable seismometers spaced approximately at an 1.5 km interval and digitally recorded for 115 s at an 120-Hz sampling rate. Normal moveout corrections were applied to yield reflection images for P, S, and PS converted waves followed by time-to-depth conversion through forward modeling of travel times using the fourth-order equation for wide angle reflections. Three distinct reflection events are identified at average two-way travel times of 4.90, 8.02, and 10.99 s on the NMO corrected P-wave sections. Their converted depths are 13.71, 23.37, and 33.67 km, respectively, and the P-wave interval velocities between the depth boundaries including the free surface are 5.60, 6.19, and 6.96 km/s from top to bottom. The reflection Moho is imaged as a sharp boundary in the middle of the profile while multi-layers are featured near both ends of the profile.
 
Article
This study evaluated the performance of the seismograph network in the southern Korean Peninsula. The average distance between stations in this network is about 25 km. According to the Gutenberg-Richter recurrence relation, the seismograph network appears to have recorded all earthquakes larger than M≈ 2.1−2.2 that occurred in the 9-year interval from 2001 to 2009. Values of a and b were estimated as 4.383 and 0.8544 by linear regression, with standard deviations of 0.06 and 0.018, and as 4.251 and 0.8293 by the maximum likelihood method, with standard deviations of 0.08 and 0.049, respectively. The results agree within 1 standard deviation. The network performance was evaluated with respect to hypocenter estimation accuracy by two hypocenter determination algorithms: the recently refined GA-MHYPO algorithm and the LocSAT algorithm used by the Korea Institute of Geoscience and Mineral Resources (KIGAM). The algorithms were evaluated with synthetic traveltime data generated using the local velocity structure and the present network geometry. In view of the velocity structure of the southern Korean Peninsula and the a priori velocity model used by LocSAT, GA-MHYPO determines hypocentral parameters more accurately than does LocSAT by a factor of five. GA-MHYPO is able to determine epicenters of events with large azimuthal gaps, whereas LocSAT yields large errors. GA-MHYPO cannot determine the focal depths of events shallower than 10 km with the present seismograph network, but if the network had ideal 10-km spacing, GA-MHYPO could accurately determine the focal depths of 5-km-deep events. The 122 earthquakes with magnitudes larger than or equal to 2.0 that occurred from 2004 to 2008 were relocated using GA-MHYPO. The determined hypocentral parameters determined were compared with those reported by the Korea Meteorological Administration (KMA) and KIGAM. Epicenter locations differed by as much as 10 km for inland events and as much as 30 km for offshore events. This may be attributed to large azimuthal gaps in offshore events and the large differences between the a priori velocity models used by the KMA and KIGAM and the true offshore velocity structure. The focal depths determined here were quite different from those reported by KIGAM, and there were many events deeper than 15 km. No relationship with tectonic structure or geology was evident. The KMA and KIGAM could improve the accuracies of hypocentral parameters in their final earthquake reports by using a better a priori velocity model in their hypocentral determination packages. Key wordshypocentral parameters–Gutenberg-Richter recurrence relation–seismograph network– a priori information
 
Article
We present results of a preliminary analysis for source parameters of the 29 May 2004 offshore Uljin earthquake. The analysis is based on a set of broadband and short period velocity seismograms, and accelerograms recorded by seismic networks in southern Korea. The estimated parameters of the mainshock are as follows: origin time 19∶14∶25.82 in Korean local time (10∶14∶25.82 UT), latitude 36.626°N, longitude 130.054°E, depth 18 km, magnitudeM w 5.1, stress drop 28 bars, one focal plane 337°, 56° and 78°, and the other plane 178°, 36° and 107° in strike, dip and rake, respectively. Three aftershocks ofM w 2.3, 2.0 and 2.4 occurred within source region of the mainshock, and two other events ofM w 2.5 and 3.5 at epicenters beyond the rupture area are presumed to be triggered dynamically by the 29 May 2004 earthquake. The largest ground acceleration, 2.62%g, was instrumentally recorded at Pohang, 90.4 km south-west of the mainshock epicenter. The maximum instrumental intensity is estimated as V and VI in Modified Mercalli Intensity scale excluding and including local effects, respectively. There is a possibility that the mainshock-aftershock sequence and one of the dynamically triggered events are directly related to the Ulleung Fault.
 
Article
An unusual earthquake sequence comprising 11 events with magnitude range ofM L 2.0 to 3.2 occurred off the eastern coast of the southern Korean Peninsula in April 2006. Since there is no obvious mainshock in this sequence unlike a typical mainshock-aftershock sequence, the seismicity pattern shows the characteristics of swarm behavior. Focal mechanism of the largest event (M L 3.2) on the 29 of April is normal to strike-slip faulting. Hypocenter relocations of nine events improve the epicenter locations that fall within an area with a radius of about 0.7 km while depths are less well constrained with ranges of 1.6 km to 13.0 km. We propose that a swarm behavior of the sequence is closely related to the marginal geometry of the Ulleung Basin and the regional stress regime. The fact that epicenters of the April 2006 sequence are at the same transitional zone of continental to rifted continental crust as that of the 29 May 2004,M w 5.1, earthquake indicates that the Ulleung Fault is seismically active.
 
Article
An earthquake occurred in the Andong area, South Korea on May 2, 2009. Korea Meteorological Administration reported its magnitude and epicenter to be ML 4.0 and (36.56°N, 128.71°E), respectively. We carried out the waveform inversion analysis to estimate source parameters of the event. The seismic moment was estimated to be 3.8 × 1014 N·m (MW 3.7). The focal mechanism is strike-slip faulting including a little weak thrust component. The direction of P-axis of the event is N70°E which is similar to the other studies on the direction of P-axis in and around the Korean Peninsula. From the spectral analysis, the moment magnitude was estimated to be MW 3.7, which coincides with that by the waveform inversion analysis. The average stress drop is estimated to be 6.5 MPa. We applied the double difference event location method with 4 events of the Andong earthquake sequence and one event on April 28, 2010. Considering nearby Andong fault systems, location results by double difference and single event location method, and focal mechanisms, the direction of causative fault may be NW-SE or WNW-ESE. Key wordsAndong-waveform inversion-focal mechanism-double difference-spectral analysis
 
Article
Age-controlled pollen record from wetland sediments of Hanam, western central Korean Peninsula (KP), reveals vegetation dynamics response to climate changes during the last glacial, 26.1–20.1 cal kyr BP. The Hanam pollen assemblages are dominated by conifers, Picea and Pinus and cold tolerant deciduous broadleaved Betula, together with common xerophytic herb like Artemisia and Gramineae. Principal taxa are similar to those of subalpine forest in modern vegetation of KP. Humidity variation reconstructed by semi aridity index (AI) indicates that, during 26.1–22.7 cal kyr BP, cold and dry conditions were prevailed with an expansion of subalpine coniferous forest and high value of AI. From 22.5 to 20.5 cal kyr BP, cool and wet conditions were reconstructed with low value of AI due to climatic amelioration, enhanced conifers and temperate deciduous broadleaved mixed forests flourished. Between 20.3 and 20.1 cal kyr BP, an abundance of Picea and Betula associated with high value of AI infers that subalpine conifers forest colonized again in hinterland montane along with open, low grassland under colder and drier conditions owing to climatic deterioration. The principal pollen taxa suggest that prevailing climate conditions were annual mean temperature about 5–6 °C colder and annual mean precipitation 40% drier than today. Key wordsPollen-vegetation-aridity index-Korea-Hanam-the last glacial
 
Article
The230Th/234U ages of fossil mollusk shells collected from the Sinyangri and Hamori Formations, the youngest stratigraphic units on Jeju Island, Korea, were estimated using multiple collectors inductively coupled plasma mass spectrometry. Seven aragonite shells yielded230Th/234U ages ranging from 3434±40 yr to 4980±33 yr (2σm), in concordance with radiocarbon ages for samples containing little232Th. Our data suggest that the230Th/234U method can be a potentially useful tool for dating Holocene mollusks, provided that there is no evidence for severe recrystallization, cementation, and considerable amount of common thorium. An early uptake of uranium immediately after burial and subsequent maintenance of closed system for uranium and thorium can be assumed for our mollusk samples. This study, together with previous radiocarbon and optical dating results, demonstrates that the Hamori Formation where human footprints were recently discovered deposited during the middle Holocene.
 
Article
Records of redox-sensitive elements (Mo, Cd, Cu, V and U), δ18O of planktonic foraminifera (δ18Opf), and organic carbon and biogenic opal contents in dark laminated mud (DLM) layers of the East/Japan Sea reveal relative role of primary productivity versus bottom-water stagnation for the formation of these layers during the last 25,000 years. Enrichments of redox-sensitive elements in these layers indicate that bottom waters were reduced during the formation of the lower DLM (22,500-15,00014C yr B.P.) and the upper DLM (10,400-10,20014C yr B.P.), probably to a greater extent in the lower layer. Anomalous low δ18Opf values and minimal contents of both organic carbon and biogenic opal suggest that bottom-water stagnation due to density-stratified water column could be more important than primary productivity for the lower DLM formation. In contrast, the relatively high contents of the organic carbon in the upper DLM invoke a primary role of enhanced productivity in the formation. This inference is, however, questioned by the absence of comparable increase in biogenic opal contents which is expected from generally coupled production of organic carbon and opal in surface water. The discrepancy between the organic carbon and opal records suggests that a bottom-water stagnation, which might have caused the preferential preservation of organic carbon in the reducing bottom-water condition, could be also more important than primary productivity for the upper DLM formation.
 
Article
To describe wave propagation in a fluid-solid environment which is usually encountered during marine seismic exploration, we design a time-domain acoustic-elastic coupled modeling algorithm based on the cell-based finite-difference method. The cellbased method has proven to delineate stress-free conditions correctly at the free surface with just changes in the material properties, which indicates that it can also properly deal with subsurface interface boundaries. In the acoustic-elastic coupled modeling, we first compose finite differences individually for the acoustic and elastic media; we then combine the differences using fluid-solid interface boundary conditions. Numerical experiments show that the cell-based coupled modeling algorithm gives solutions compatible with analytic solutions and that it properly describes S- and converted waves as well as P-waves. Applying the cell-based coupled modeling algorithm to a slope model, we confirm that our coupled modeling algorithm describes irregular interfaces properly, although it employs a staircase approximation of them.
 
A map showing the localities of rock samples containing >3.0 Ga zircon components (from Cho and Kim, 2003; Jeon et al., 2007; Wu et al., 2007; this study). The U-Pb, TDMC1 and TDMC2 ages in the box correspond to the SHRIMP 2 0 7 Pb/ 2 0 6
Lu-Hf isotope data for >3.0 Ga zircons from the Korean Peninsula
Cathodoluminescence images of the >3.0 Ga zircon grains from the Gyeonggi and Yeongnam massifs. Each spot of the SHRIMP analysis (ca. 30 μm in diameter) is shown together with the common Pb-corrected 2 0 7 Pb/ 2 0 6
Article
We report in-situ Hf isotopic data on five inherited zircon components, dated at > 3.0 Ga from previous Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb analyses. These data are useful for constraining the timing and nature of very pristine crustal materials in South Korea.176Hf/177Hf isotope ratios, measured using a laser ablation Multi-collector Induced Coupled Plasma Mass Spectrometer (MC-ICP MS), range from 0.28044 to 0.28075, corresponding to the present-day εHf(0) of −70 to −81. They yield two-stage Hf model ages of ca. 4.1 to 3.5 Ga at the time of zircon crystallization from a magma, depending on tenable crustal evolution models. Our results provide the first Hf isotopic evidence for existence of Paleoarchean (>3.5 Ga) crustal components in the Korean Peninsula.
 
Article
The understanding of detailed 3D basin structure is very important for seismic hazard analysis because ground shaking can be both amplified and prolonged due to basin effects and causing significant damage. Background seismic noise is ubiquitous and continuous and these characteristics make ambient seismic noise useful to study velocity structure because neither infrequent earthquakes nor expensive explosions are needed. The horizontal to vertical (H/V) spectral ratio method is a common technique to study the structure of the basin using background seismic noise. Many observations of the H/V ratio recorded at seismic stations over basins display systematic decreases in the frequency of the dominant H/V peak with increasing basin thickness. However, some observations cannot be fully explained by theoretical simulations of the H/V ratio based on 1D velocity profiles beneath the stations. In order to study the precise relationship between the H/V ratio and the basin structure, wavefield simulation of background noise for 3D velocity structure can be quite useful. However, this simulation is still far from being routine because our knowledge of the noise source is quite poor. In this paper, we propose a simple technique to directly simulate the H/V ratio instead of the wavefield of background noise. To evaluate the method, we performed numerical experiments for the Santa Clara Valley and the results show that the synthetics can predict the observations well. We also performed several sensitivity tests for the source and the velocity structure of the basin and found that Rayleigh type wave propagation and a minimum velocity contrast between the basin and background media are required to make the H/V ratio sensitive to the basin structure. Although we also found that the H/V ratio technique has a limitation in determining small scale basin structure at deeper depth, this technique can still be used to evaluate pre-existing velocity models and give some constraints on the development of new velocity models for the basins.
 
Article
A regional seismic-reflection survey, Line 42 of the LITHOPROBE Sudbury transect traverses the Levack gneiss, northwest of the North Range, associated with the Sudbury Structure. Preliminary processing by industry contract produced a section that shows no significant reflection events at shallow depths (0–3 s), particulary in the southern portion of the line close to the North Range. The Line 42 data set was reprocessed with an objective to improve spatial resolution of the seismic image so as to resolve lingering questions related with the uplift of the Levack gneiss complex. The reprocessing emphasized spectral balance, f-k filtering, refraction statics, cross-dip correction, velocity analysis cascaded with residual statics, and offset-limited stack, which greatly improved the final seismic section. The reprocessed seismic section has revealed several reflection events in the northwestern outer portion of the Sudbury Structure. Two of these events are interpreted together with the C-Band SAR (synthetic aperture radar) image data acquired from the satellite ERS-1 of European Space Agency. A reflection event AA′ associated with the interface between the Levack gneiss and the Cartier granite dips southeast, and its surface projection falls approximately 1.5 km north of the geological boundary (Dressler, 1984a). The reflection event R2 extending through most of the line appears to represent a major fault (or a shear zone) which dips southeast and is parallel to the geologic boundary between the Levack gneiss and the Cartier granite. The seismic patterns imaged on the north side of Event R2 are considerably different from those of the southern side and may represent new geological fabrics of the rocks. The reflection event R1 in the southern portion of the line, near Pumphouse Creek, appears nearly vertical at shallow depths and may correspond to the Pumphouse Creek fault (Dressler, 1984a).
 
Article
A geochemical analysis is conducted on hemipelagic sediments at ODP Leg 162, Site 907, North Atlantic. On the basis of major and minor element concentrations, the sequence is divided into five units. Geochemical data reveal that the sediments originated from two specific source areas, i.e., continental icerafted debris (IRD) and Icelandic basalt. In the upper part (lithological units I and II, 0 to 63.1 meters below sea floor (mbsf)), sediments were derived from continental IRD, whereas in the lower part, sediments (lithological units III, IV, and V, below 63.1 mbsf) comprise mixture of continental IRD and minor supply from the Icelandic basalt. The ratio of TiO2/Al2O3 to SiO2 content and the Th to Ti/Al molar ratio clearly provide a key to discriminate provenances. The change in source area is most likely related to the oceanographic and climatic evolution in the North Atlantic since the middle Miocene. Biogenic fossil-barren intervals (Units II and V) are considered as a consequence of dissolution caused by oceanic circulation. The timing of IRD initiation confers with that of geochemical analysis. Total organic carbon to total nitrogen (C/N) ratio shows a striking variation in the entire core. The C/N ratios exceed 10 below approximately 196 mbsf (lithological unit V) with a gradual downward increase. This suggests that terrigenous organic matters have been supplied from the neighboring continents. The total organic carbon to total sulfur (C/S) ratio also shows such possibility as well as diagenetic changes in Units IV and V. The carbonate-barren intervals presented in Units II and V, and intermittently in Units III and IV are interpreted as a consequence of dissolution effect related with climatic variation and deep-water circulation. Additional low surface productivity was considerable.
 
Article
Sediments from Ocean Drilling Program (ODP) Sites 980 and 983 in the North Atlantic Ocean were analyzed to obtain evidence of long-range Milankovitch cycles and to examine the cycles' effect on the paleoceanographic evolution of the North Atlantic Ocean. Wide cyclic variations in total organic carbon and biogenic carbonate occur throughout the columns at both sites and provide distinctive characteristics of both sediment groups. Spectral modeling of these variations shows typical 100-ka cyclic variations in both the total organic carbon (TOC) and carbonate records at Site 980, although this 100-ka Milankovitch frequency occurs only in the upper, ≈472,5 ka, section of the core. In Site 983, only 400-ka cycle in carbonate is observed but the 100-ka cycle in TOC and carbonate is absent. The terrigenous content, expressed in terms of K, Al, Ti, and Th, also shows strong 100-ka and 400-ka cyclic variations at Site 983. The earth's eccentricity as expressed 100-ka and 400-ka cycles, and no appearance of obliquity (41-ka) and precession (23-ka) are important characteristics of North Atlantic Ocean sediments. Milankovitch pulse differences in carbonate, TOC at the two sites likely arise from the evolution of paleocean-ography. The dilution of carbonate fractions by terrigenous materials (indicated by the cyclical behavior of trace elements) at Site 983 is one of plausible explanation. Climatic warming over the last 600 ka probably caused the differences in the sedimentary cycles at the two sites; induced meltwater discharge is recorded in the terrigenous record, and changes in the oceanic circulation system are related to major glacial-interglacial climatic episodes that probably underlie the differences in the cyclical records.
 
Article
In the Mae Sot and Umphang areas (NW Thailand), Jurassic strata seal the Permian and Triassic substratum of the Shan-Thai terrane with a brecciated conglomerate. Pliensbachian to Early Bajocian shallow marine strata are intercalated within the partly terrestrial Jurassic sequence. Thirty-five Toarcian-Aalenian bivalve species from Mae Sot and Umphang were identified. Among these,Eomiodon chumphonensis Hayami is known only from Thailand, whereasParvamussium donaiense (Mansuy),Myophoriella saurini Hayami,Thracia loducensis Hayami,Pholadomya (Bucardiomya) fontainei Hayami,Thracia loducensis Hayami andModiolus sestiniae Hayami were originally described in Vietnam.M. sestiniae also occurs in Iran. The greater part of the fauna, however, shows varying degrees of affinity with Myanmar (6 species), Cutch (10 species), Japan (13 species) and Europe (9 species), Levant (2 species). In view of these, it appears that these highly endemic Toarcian-Aalenian bivalves from Thailand characterize the Southeastern Asian Province of Tethys.
 
Article
The geochemical properties (acidity, elemental composition, and isotopic composition of Sr and Pb) of surface water in the watershed of the abandoned Dongjin Au-Ag-Cu mine, central Korea, vary as the water drifts downstream and reacts with refuse ore piles. These properties also change due to adsorption and co-precipitation of metals on Fe-Al precipitates, and dilution by unpolluted waters. The patterns of variation of dissolved ions were divided into two groups (1 and 2). Group-1 ion (Al, Cu, Cd, and Pb) levels are increased only in acidified water after reaction with refuse ore piles, and their concentrations are regulated largely by precipitates of amorphous Fe-Al hydroxides, which strongly adsorb or precipitate these metals in mildly acidic to neutral conditions. The selective adsorption of Pb on Fe-Al precipitates is supported by Pb isotope data, suggesting that Pb from ore is dominant only in acidic water (pH < 6.0) because of weak, negligible adsorption (< 5%). On the other hand, atmospheric Pb becomes dominant in near-neutral water (pH > 6.0) even with high contents of other ions from dissolved sulfide minerals because of strong adsorption of Pb from ore. Group-2 ions are composed of the major cations (alkali and alkaline-earth), anions, and trace elements including Zn and Mn. Their concentrations and 87Sr/86Sr ratios tend to decrease with distance from the mine adit, indicating that group-2 ions are less dependent on pH and are strongly controlled by mixing with unpolluted, dilute water from the surrounding areas. A combination of Pb and Sr isotopes is useful for tracing the geochemical evolution of surface water in acid mine drainage.
 
Article
We evaluated the feasibility using waste lime for reclaiming abanndoned coal mines. For this evaluation, lime wastes were reused in neutralizing coal wastes in a field experiment. In runoff and leachate, pH and heavy metals were monitored for approximately 4 months to evaluate ecotoxicity at the remediation site. When the amount of added lime cake was equivalent to the 100% lime requirement for neutralization, stable neutralization was obtained during the entire experimental period. Because of pH neutralization, ecotoxic heavy metals were efficiently contained in the coal waste pile. When smaller amounts of lime cake were applied, although heavy metal releases did not increase, the pH in runoff/leachate fluctuated depending on the amount of precipitation and the history of field treatment. This suggests that field specific environmental factors have to be considered in determining the amount of lime cake required for stable neutralization. These findings from the field study demostrated the potential use of lime waste from soda ash production for reclaming abandoned coal mines.
 
Article
Stable oxygen- and carbon-isotope and X-ray mineralogical analyses are used to obtain information on ice-rafting (Heinrich) events in the eastern North Atlantic during the last glacial period. A sediment core collected from the continental slope off Portugal reveals that the X-ray mineralogy of some ice-rafted debris (IRD) layers is similar to that of the Heinrich layers H1, H2, and H4 in the North Atlantic, although the quantities of various detrital fragments are relatively low. The IRD layers are marked by a maximum abundance of planktonic foraminiferaNeogloboquadrina pachyderma (sin.), minima or lowered values of planktonic δ18O (Globigerina bulloides), and negative δ13C anomalies of benthic foraminiferaCibicidoides wuellerstorfi. Significant decreases in seasurface temperature and salinity are also characteristic. These data suggest that the icebergs passed along the western Iberian margin were of the same origin as those which led to the formation of Heinrich layers in the North Atlantic. In particular, a decrease in benthic δ13C of the IRD events implies a decreased ventilation of the North Atlantic that may have enhanced the advection of a12C-enriched intermediate water from the south. The absence of an IRD layer corresponding to the Heinrich layer H3 in the studied cores suggests that the reduction of convection in the North Atlantic prevented the iceberg drifting to the study area off Portugal during the period H3.
 
Article
A core taken from a mudline of Hole 1120A (ODP Leg 181) located in the Campbell Plateau, Southwest Pacific Ocean documents the deglacial variation of calcium carbonate contents. Stable isotope profiles of planktonic and benthic foraminifera and a radiocarbon AMS dating (11,260 ka) constrain the age of deglaciation. Abrupt increase in the calcium carbonate contents during the deglaciation is a result of complex combination of dissolution, production, and dilution. Dissolution of bottom water plays insignificant role in Site 1120 due to the bathymetric high site above the present lysocline. The reduction in dilution of noncarbonate terrigenous particles is considered as a major reason to show the enhanced calcium carbonate contents during the Holocene. Such chalk-marl cycle of Atlantic-type carbonate variation can be observed in the Southwest Pacific Ocean.
 
Article
This paper briefly describes the geology of southern Sikhote-Alin of Russia and the Inner zone of Southwest Japan, and presents a new correlation model in which the Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation and Kalinovka ophiolite in Sikhote-Alin are considered as northern extensions of the Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in Southwest Japan, respectively. This correlation is based on the similarities in lithology, age, faunal assemblage, and structural relationship between them. The Samarka and Mino-Tamba terranes consists of Jurassic accretionary complexes including Permian greenstone-limestone complex, Permian to Lower Jurassic radiolarian bedded chert, Jurassic clastic rocks, and Jurassic melanges. The Udeka and Hikami formations are composed mainly of greenish gray sandstone with minor shale intercalations yielding Permian radiolarians. The Sebuchar and Kozuki formations are characterized by basalts accompanied with shale, limestone and chert. The limestone includes Carboniferous fusulinaceans, while Permian radiolarians occur in the chert. The Kalinovka and Yakuno ophiolites consist of a series of ultramafic to mafic igneous rocks with an ophiolitic succession. Since the ages of these ophiolites have not been clearly established, we correlate them on the basis of their lithology and tectonic positions. These units form a stack of nappes from the lower to upper horizons in the following order: Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in Japan, and Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation, and Kalinovka ophiolite in Russia. This correlation supports the reconstruction model of Japan before the opening of the Sea of Japan proposed by Yamakita and Otoh (1999).
 
Article
In this study, geotechnical properties of the subsurface clay stratum obtained from the in-situ tests are compared with those of the relative laboratory tests. The influence of accumulated leachate on the settlement of the landfill and the geotechnical properties of underlying clayed soil are analyzed using the in-situ measured settlement data. The consolidation data is then back-calculated from the settlement data and compared with the laboratory scale consolidation data. It was found that the settlement was retarded by the accumulated leachate and the consolidation properties obtained from the field measurement were 1.5 times higher than the laboratory obtained data, which proves the importance of field measurement of geotechnical data during the operation period.
 
Article
In Masan Bay, the drainage basin for the wastewater of heavily-industrialized cities and harbors in the southeastern Korea, a composite analysis of sediment cores reveals that accumulation history and behaviors of heavy metals are distinctive depending on anthropogenic activities and dissolved oxygen in water column. In the inner bay, Cu, Zn, and Pb have been enriched, associated with organic and sulfide matter, over background levels since the mid-1940s. It seems to result from the deposition of stream-disposed sewage under a poor water circulation before most of sewage collected in Masan City has been treated and disposed through an outfall into the outer bay since the late 1993. The outfall disposal contaminated the topmost sediments of the outer bay with the three metals, 2.2 to 3.2 times as much as the background. The three metals are strongly associated with Mn in the bay mouth, probably resulting from their oxidative precipitation beneath a chemical front of water column that forms by expansion and mixing of anoxic bay bottom water with oxygenated coastal water. The bay sediments seem to act as a mobile pool in that Mn and the pollutant metals are often remobilized to the anoxic bottom water in summer.
 
Article
Contractional tectonism, associated with the backarc closure of the East Sea (Japan Sea), resulted in a series of thrust and anticline along the southern margin of the Ulleung Basin, providing numerous traps that include the Dolgorae and Gorae structures. Restoration of depth-converted seismic profiles suggests two phases of contractional deformation in the area: (1) the latest Early to late Late Miocene phase that created the Dolgorae structures and (2) the late Late Miocene to Quaternary (?) phase that created the Gorae structures. The second phase of contractional deformation was accompanied by transpressional strikeslip movements. The formation of the Dolgorae II and Gorae structures postdated the main phase of oil generation but overlapped and/or predated the main phase of gas generation. The Dolgorae I and III structures began to form during the later stage of oil generation but did not have significant relief until the beginning of the main phase of gas generation. Thus, potential for large oil accumulations in the area is probably limited. Older and deeper structures, predating the contractional deformation, may have accumulated oil if later tectonic movements had not disrupted their trap integrity.
 
Article
The authors have evaluated the effect of spatial resolution on the accuracy of landslide susceptibility mapping. For this purpose, landslide locations were identified from the interpretation of aerial photographs and field surveys in the Boun region of Korea. Topography, soil, forest, geological, lineament and landuse data were collected, processed, and constructed into a spatial database using GIS and remote sensing data. The 15 factors that influenced landslide occurrence were extracted and calculated from the spatial database at 5, 10, 30, 100 and 200 m spatial resolution. Hazardous landslide areas were analyzed and mapped using the landslide-occurrence factors by employing a probability models frequency ratio for the five spatial resolutions. The results of the analysis were verified using the landslide location data and area under success rate curve. The spatial resolutions of 5, 10 and 30 m showed similar results (the normalized area values 0.97, 1.00 and 0.92, respectively), but the 100 and 200 m spatial resolutions showed less well-verified data (the normalized area values 0.48, and 0.00, respectively). Because the scale of the input data was 1∶5,000–1∶50,000, the 5, 10 and 30 m spatial resolutions had a similar accuracy, but the 100 and 200 m spatial resolutions had a lower accuracy. From this, we conclude that spatial resolution has an effect on the accuracy of landslide susceptibility, as it is dependent on the input map. At least, less than 30 m resolution is need for landslide analysis in Korea where most of map scale is in the range 1∶5,000–1∶50,000.
 
Article
Acer pohangense sp. nov. belonging to Aceraceae is described based on the six detached samaras collected from the Duho Formation of the Miocene Yeonil Group. This species is characterized by its comparatively large-sized samara with a wing and seed, and its wide divergent angle. The occurrence of such a large-sized samara is the first on record not only in the Korean Tertiary floras, but also in the East Asian Tertiary floras.
 
Article
Analysis of Chirp profiles from Jinhae Bay, southern Korea, revealed three sediment echo types (echo type I–III) and acoustic anomalies associated with shallow gas such as acoustic blanking and turbidity. Echo type I, characterized by low-to-high amplitude internal reflectors, almost parallel to the seafloor and seen away from the Gadeog Channel, probably represent mud from the Nakdong River that moved into the area by bayward transport. Echo type II, characterized by truncation at the seafloor and seen only in the Gadeog Channel, is interpreted to be tidal-channel deposits. Echo type III is acoustically transparent and interpreted as distal prodelta deposits. The acoustic blanking and turbidity were further divided into AB-I-III and AT-I-II, respectively. AB-I has a very strong, shallow top reflection that is parallel to the seafloor, crosscutting the stratigraphy. Depths of AB-I may correspond to the sulphate-methane transition that remains shallow probably due to large supply of methane. The top reflection of AB-II is of high amplitude and follows the bedding planes, probably controlled or limited by lithology. AB-III is characterized by a very irregular or highly diffractive and strong top reflection, which may be due to very closely-spaced patches of high-concentration gas. AT-I exhibits a weak and highly irregular top reflection, suggesting low gas concentration. AT-II, comprised of isolated weak diffractions, is likely due to isolated accumulations of low concentration gas. C/N ratios (6.8–8.6) of the organic matter in the cored sediments in the study area suggest mixed marine and terrestrial sources.
 
Article
Normal incident acoustic techniques were used to determine values of sediment properties (acoustic impedance, sound speed, bulk density, porosity, shear strength, water content, and mean grain size) and map those (acoustic impedance and grain size) in the northeastern Gulf of Mexico. The acoustic data were acquired using a 11 kHz normal incident echo sounder over approximately 2000 km of track line. A calibration factor for echo strength was determined by the comparison of acoustic data to measured impedance from five core samples (ground truth data). This echo strength calibration was used for the entire data set. Values of sediment properties were calculated from sediment impedance using the regressions compiled from the historical core database. Comparison of ground truth and echo strength to data from 20 additional core locations shows close agreement. Discrepancies are probably due to navigation errors or weak returns in deeper water. In addition, sediment disturbance and frequency dispersion can be considered. Using acoustic derived sediment properties, four sediment provinces of the study area are defined as the following types: sandy/silty clay (impedance, 1.6–2.0 106 kg/m2 s), sand-silt-clay and/or clayey sand (impedance, 2.01–2.40 106 kg/m2 s), silt or fine sand (impedance, 2.41–2.90 106 kg/m2 s), medium/coarse sand (impedance, 2.91–4.0 106 kg/m2 s). The areal distributions of the four types coincide with the previous reports based on sediment sampling. Therefore, the acoustic technique can effectively be used to define and classify sediments and map sediment provinces.
 
Article
The objective of this study is to evaluate the effect of ionic strength and hardness of trichloroethylene (TCE)-contaminated synthetic groundwater on remediation using granular activated carbon (GAC). The TCE sorption rate onto GAC in synthetic groundwater was observed by batch experiments and ranged from 86.2% to 100%. As the ionic strength and hardness of the synthetic groundwater increased, the TCE sorption rates decreased. The sorption kinetics of the GAC were also analyzed by kinetic models. The Elovich model was more successfully applicable to the sorption kinetics than the Pseudo-first-order model. During the sorption, a greater amount of cations in groundwater were adsorbed than anions. The sorption capacity of GAC was affected by cations in groundwater. The GAC surface area was 958.98 m2/g and the calculated TCE and ions sorption areas were 318.38 m2/g, which comprised 33.2% of the GAC surface area. Our experiments showed that TCE remediation was influenced by the ionic strength and hardness of groundwater. The results of these experiments were confirmed by two different models and sorption areas. Therefore, the ionic strength and hardness of groundwater must be considered in the remediation of TCE-contaminated groundwater using GAC.
 
Article
The Cretaceous period was generally characterized by greenhouse conditions. Nevertheless, our data on isotopic composition of biogenic carbonates from the Koryak Upland and Sakhalin (Russian Far East) show that during the Maastrichtian, temperatures dropped sharply at high and middle latitudes, with only a slight warming in the early Late Maastrichtian. At the same time, there is contradictory evidence on climatic conditions for low latitude areas during Maastrichtian time. The new and previously published isotopic data on Maastrichtian mollusks in the Western Interior Seaway (North America) (WIS) and some other areas suggest that tropical deep-sea surface temperatures calculated from the oxygen isotopic composition of the majority of investigated Maastrichtian planktic foraminifera are, obviously, underestimated. Unusually low isotopic temperatues were obtained for tropical planktic foraminifera. This probably reflects both local conditions provoked, first of all, by the influence of tropical upwelling zones, and the ability of Maastrichtian planktic foraminifera to migrate within a large vertical interval in the tropical zone in conditions of weakly stratified (well-mixed) ocean. The average tropical deep-sea surface paleotemperature estimates for the Maastrichtian could have been about 26.6–30.2°C, but, apparently, did not reach the level denoted for the Late Albian and Turonian (32±3°C). Negative carbon-isotopic shifts at the end of the early Maastrichtian and the Cretaceous-Tertiary boundary time seem to be connected with the fall of temperature and eventual reduction of oxygen content in the atmosphere and hydrosphere.
 
Experimental conditions for electrokinetic tests.
Removal efficiency of phenanthrene in soil.
Article
Removal of hydrophobic organic contaminants (HOCs) using an additive-enhanced electrokinetic method was studied in a model system. Kaolinite and phenanthrene were selected as a model clay soil and a representative HOC, respectively. Three different chemically-synthesized surfactants along with two different biosurfactants were used to remove phenanthrene. Hydrogen peroxide was also used to degrade phenanthrene. Electrokinetic (EK) column experiments were performed using these additives. When no additive was used, a removal efficiency of phenanthrene was 4.23% after 2 weeks. When surfactants were added in the EK system, the removal efficiencies after 2 weeks were as follows: APG 11.1%, Brij 30 6.31%, SDS 9.97%, MEL 16.2% and BS-UC 17.4%. Among surfactants, biosurfactants had higher removal efficiencies than chemically-synthesized surfactants. When hydrogen peroxide was used, 54.7% of initial amount was removed at a current of 5 mA for 2 weeks. Even a higher removal efficiency was achieved (84.2%) at 10 mA within 1 week. These results suggest a detailed future study on the chemical treatment by hydrogen peroxide incorporated with EK method to remove phenanthrene from clay soil.
 
Article
New graptolite material from the Mungok Formation, Yeongwol, Korea, suggests that psigraptids evolved from a species of Ancoragraptus. The main trait of the proposed lineage is a reclined rhabdosome, stipe reduction, and metathecal separation. Ancoragraptus psigraptoides new species, which is the intermediary between Adelograptus sp. 1 and Psigraptus jacksoni, is described. The free metasicula and slightly reclined stipes appear first in Ancoragraptus psigraptoides. A possible route for the lineage is discussed: Adelograptus sp. 1-Ancoragraptus psigraptoides-Psigraptus jacksoni.
 
Article
The current study is undertaken to evaluate the anthropogenic influences of groundwater during tidal cycles in Bicentennial Park adjacent to Rozelle Bay, Sydney, Australia and to explain the geochemical processes controlling trace metal distributions. Results reveal that major ion and trace element compositions of groundwater are predominantly influenced by different types of waste materials (construction materials or dredged marine sediments) disposed in the study area. Major ions in the groundwater exhibit a concentration order of Na≫Mg>Ca>K (equivalents) for areas containing construction waste materials, whereas for areas comprising dredged marine infill sediments it is Na>Ca>Mg>K (equivalents). Similarly, an anionic order of Cl>SO4>HCO3 was observed for areas containing construction materials and HCO3>Cl>SO4 for areas comprising dredged marine infill sediments. The trace metal concentrations indicate that the total dissolved concentrations of As, Cr and Cu relative to chloride collected from the reclaimed land along coastline increase as chloride increases, while the concentrations of Fe and Mn relative to chloride in groundwaters relatively decrease as chloride increases. No trends are apparent for trace, metals such as, Pb, Zn, Ni and Co. There are a number of factors controlling the trace metal concentrations, and hence migration, in the groundwaters associated with landfill materials, which include the redox behaviour of the groundwater, water table fluctuation, fill compositions buried at the site, dilution of seawater by the ingress of freshwater from upgradient of the filled area. Results of this study reveal that the natural hydraulic gradient of the groundwater will lead to elevated concentrations of trace metals (As, Cr, Cu, Pb, Zn) entering the estuary from waste materials used for infill at the site.
 
Article
Planktonic foraminifera collected from the entire 200 m water column in the western Weddell Sea using vertically-towed nets consisted largely ofNeogloboquadrina pachyderma (s) andGlobigerina quinqueloba. Peak abundance of planktonic foraminifera occurred in low-nutrient waters adjacent to the sea ice margin. Nearly all specimens ofN. pachyderma (s) in the > 250 μm size class possessed a kummerform final chamber, but less than 20% added gametogenic calcite to the exterior of their shells. The frequent occurrence of δ18O values ofN. pachyderma (s) lighter than the δ18O in equilibrium with ambient surface waters presumably indicates that significant growth occurred either out of isotopic equilibrium or in water beneath the ice shelf containing18O-depleted snow melt. We suggest herein that the variation between δ18O and δ18O is most likely due to secretion of shell carbonate in water influenced by snow melt or glacier melt.
 
Article
In the Hunghae Formation of the Pohang Basin, some heavily armored, calcareous mudstone balls (boulders) occur in a chaotic conglomerate bed which was deposited from debris flow on a steep slope. Sparsely armored or unarmored mudstone balls are also found in the same bed. Also some isolated armored mudstone boulders occur in a homogeneous mudstone bed of the formation which is interpreted as hemipelagite. The armored mudstone balls were most likely formed by retrogressive failures of submarine channel or scar wall and subsequent rolling over sand and pebble pavement along the submarine channel floor prior to incorporation into the debris flow. Their occurrence also suggests that a large-scale slumping should be happened on the upper slope apron or lower prodelta including the submarine channel and be evolved into debris flows, resulting in the corporation of the boulders into them. Some armored mud boulders rolled along and passed away the channelized gravel pavement, and deposited on hemipelagic mud in lower slope, not having been reworked.
 
Article
Measurements were made of the adsorption of lead, cadmium, zinc, nickel and uranium per unit surface area of microorganisms, two clays (reference smectite, kaolinite), and two soils (untreated Vertisol and treated Vertisol) to quantify the selective affinity. The adsorption of heavy metals and uranium by the samples was influenced by soil constituents, and increased with increasing Pb, Ni, Zn, Cd and U concentrations. Microorganisms were also compared with these abiotic soil constituents for their ability to adsorb these metals. Dead cells adsorbed the largest quantity of all heavy metals than live cells and other soil components. At pH 6.0, the uptake percentage of U(VI) by dead cells was higher than that of any of the other metal ions. On the basis of amounts of adsorption on adsorbents, the selectivity sequences were varied. The most common sequences were U≫Pb>Cd≈Zn>Ni. The results verified the importance of geochemical parameters of soils such as type of clay mineral, oxide mineral content, and organic content, for controlling metal uptake. The results also suggest that bacterial membrane cells can be successfully used in the treatment of mixed metal-contaminated wastes.
 
Adsorption densities (Γ) of phenol and chlorophenols on Ca-montmorillonite as a function of the equilibrium concentrations (Ce) of the organic molecules in aqueous solutions. The solid lines represent the lines by linear regression, the thin broken lines the extrapolation of the regression lines to the origin and outside of the experimental concentration range, and the thick broken line the extrapolation of the data of Zhang et al. (1990). R represents the correlation coefficient for the regression line.
Freundlich isotherms of the adsorption of phenolic compounds on Ca-montmorillonite. The solid lines represent the regression lines and r the correlation coefficient.
Article
Adsorption of phenol, 2-chlorophenol, and 2,4-dichlorophenol on Ca-montmorillonite was studied with batch experiments at 25°C. The results from the experiments show that the amount of the adsorption of the phenolic compounds increases with chlorination, i.e., phenol <2-chlorophenol <2,4-dichlorophenol. This adsorption trend is due to the differences in the affinity of the phenolic compounds between the adsorbent and water, that is more affinity to water leads to less adsorption. The adsorption of phenol is unrecognizable, while 2,4-dichlorophenol is showing the highest adsorption density despite the repulsion between dissociated dichlorophenol anions and montmorillonite surface. Freundlich model fits moderately well to the adsorption isotherm of 2-chlorophenol and 2,4-dichlorophenol. The calculated model parameters aren=1.50, 0.49 and logk F =0.51, 1.09 for 2-chlorophenol and 2,4-dichlorophenol, respectively.
 
Article
Batch experiments were carried out at 25°C to obtain the adsorption isotherms of phenol, 2-cholorophenol, 4-chlorophenol and 2,4-dichlorophenol on hexadecyltrimethylammonium-exchanged-and tetramethylammonium-exchanged-montmorillonite (HDTMA-M and TMA-M) prepared from Wyoming bentonite SWy-2. The isotherms were interpreted principally using the Freundlich model. The reaction orders (n) and Freundlich constants (k F) for the adsorption of an adsorbate on HDTMA-M and TMA-M remain approximately constant against the variation of adsorbate to adsorbent ratios. Then value for most of the phenolic adsorbates on HDTMA-M is close to unity, indicating Langmuir-type adsorption but that on TMA-M is variable among different phenolic adsorbates. The degree of adsorption of phenolic compounds on HDTMA-M is primarily controlled by the hydrophobicity of the adsorbates but those on TMA governed by the complicated combinations of size, shape and hydrophobicities of the adsorbates. The estimated model parameters for the adsorption isotherms on HDTMA-M are in disagreement with those of earlier workers probably because of the differences in experimental conditions. This study also estimated the model parameters on TMA-M, which are not available in the literature.
 
Article
This study investigates the backscattering properties of C-band RADARSAT (SAR) signal over sloping mountainous areas, and evaluates the utility of RADARSAT in natural disaster areas (e.g., forest fires), geological mapping, monitoring of natural hazards, natural and associated Earths environmental changes. Conventional change detection techniques in remote sensing are adequate for most applications. However, the changes in backscattering coefficients (σ0) before and after, for example, forest fires are not apparent in certain cases, mainly because of the effects of steeply sloping target scattering surface areas. The slopes of a mountainous test site can be divided into two cases with respect to the incident SAR signal look direction: the front and back slopes, where local incidence angles can vary significantly. Depending on the slope of the scattering surface, the backscattering coefficient increases to the maximum of 3.3. dB in the front-slope, but decreases 4.5 dB in back-slope after forest fires. Forest fire burnt areas provide a good example of a natural sloping scattering surface, which exhibits subtle changes in backscattering coefficients similar to the lithological changes in nature. The April 2000 forest fire in Kangwon province, Korea, burned for several weeks and was one of the worst ones in recent years. Among several firedamaged sites, an area near Samchuk city was investigated in detail with a set of multi-temporal RADARSAT Synthetic Aperture Radar (SAR) data to estimate the fire damages as compared to the unburnt background.
 
A simplified topographic map of the study area in central part of South Korea, showing the localities of rainwater sampling ('A' to 'E' and 'a' to 'd' along the two transects) and two stationary sources of air quality change. Locations of Jecheon (JC), Yeongweol (YW), and Danyang (DY) are also shown.
Frequency analyses of rainfall measurement data with the prevailing wind direction at the city center of Jecheon, Korea
Summary of the precipitation chemistry (June 1998) along the transect from JC to YW
Changes of the calculated enrichment factors for the acidity (EFa) (in a) and Ca 2 + (EFc for Ca 2 +
Article
Meteorological and geological factors affecting the pH and ionic concentrations of precipitation were investigated from Jecheon City, Korea. The air quality of the study area is affected by two contrasting stationary sources: 1) a coal-fired power plant to the east-northeast and 2) limestone quarries and cement-manufacturing factories to the east to south-southeast of Jecheon. The temporal change of rainwater chemistry is affected by the interaction between acidic gases and alkaline substances from the above two sources. Accordingly, rainwater pH at a city center widely varies from 4.9 to 8.3. Acidic gases from the power plant are likely to acidify the rainwater pH. As the prevailing wind direction during rainfall events shifted to ENE-SSE, rainwater pH at the city center rapidly increased to >6.5 (up to 7.8). Concomitantly, ionic concentrations (esp., Ca, K, and Na) increased sharply, especially when winds are brown from SE, probably due to major influences of particles coming from limestone quarries. The enrichment factor analyses of acidity and cations also indicate that the acidic components in precipitation are mostly neutralized by limestone particles. In addition, rainwater chemistry showed a spatial variation as a function of the direction and distance from the above two sources. Our results demonstrate a good example of competing roles between the anthropogenic acidic source and the geologic alkaline source.
 
Location and geologic map of Phuoc Thanh area, Central Vietnam (modified from KORES, 1999).  
Summary of the microthermometric data of fluid inclusions in the Phuoc Thanh area, Central Vietnam. 
Relationship between salinities and homogenization temperatures of fluid inclusions in quartz from the Phuoc Thanh area, Central Vietnam.  
Homogenization temperature−XCO2 plot for fluid inclusions in quartz from the Phuoc Thanh area, Central Vienam. The solvi for fluids with 6 wt% NaCl are shown for 500 bars of pressure (after Bowers and Helgeson, 1983).  
Article
CO2-rich fluid inclusions from quartz veins provide information about pressure-temperature conditions, as well as effervescence, in the gold-silver-bearing quartz veins in the Phuoc Thanh area, Central Vietnam. Homogenization temperatures of fluid inclusion are bimodal, and support textural evidence that mineralization occurred in two stages. 90% of the fluid inclusions in the quartz are CO2-bearing. The trimodal distribution of CO2 mole fraction of the inclusions are common in the area, which indicates the CO2 unmixing, resulting the separation of the high (type IIb) and low (type IIa1) XCO2 fluids from the parental fluid (type IIa2) with intermediate XCO2. The precipitation of associated sulfide and Au−Ag minerals is related to CO2 effervescence with a concomitant decrease in sulfur activity. The temperature of mineralization is estimated as the range from 300 to 380°C in stage I and from 230 to 300°C in stage II. Pressure of ore formation ranged from 350 to 500 bars during both stages.
 
Article
The Quaternary basalts along the Chugaryeong Fault zone in central part of the Korean Peninsula are composed of two stratigraphic units in the Jeongok area, calling the Chatan and Jeongok basalts. K-Ar analyses of the mixture of the fine-grained plagioclase and anorthoclase from the 18 basalt samples were carried out to reveal the volcanic activity of the area. The results show that the Chatan and Jeongok basalts give a uniform age, giving the weighted average ages of 0.15 ± 0.01 and 0.51 ± 0.01 Ma, respectively. This reveals the age gap between the Chatan and Jeongok basalts was 360,000 years, providing a unique volcanic history for the Quaternary volcanism. The volcanism formed the two large amounts of alkali olivine basalt flows that are similar to each other in primitive chemical composition, phenocryst composition and viscosity with an interval of 360,000 years. The results also make a time constraint on the Jeongok Paleolithic Site where the Jeongok basalt occurs below the sediments containing the Paleolithic artifacts. The age (0.51 Ma) of the Jeongok basalt provides the lower limit for the age of Paleolithic artifacts. Olivine phenocrysts from both the Chatan and Jeongok basalts have significant amount of excess argon, giving apparent older ages on the whole rock K-Ar dating by previous researchers. Key wordsChugaryeong Fault zone–Quaternary basalts–Jeongok basalt–Chatan basalt–K-Ar ages
 
Top-cited authors
Biswajeet Pradhan
  • University of Technology Sydney
ِDr. Ahmed M. Youssef
  • Saudi Geological Survey
Saleh Abdullahi
  • Islamic Azad University, Esfahan
Massih Afghah
  • Islamic Azad University Shiraz branch
Hamid Reza Fadaei