Morphological identification of <Emphasis Type="Italic">Alexandrium</Emphasis> species (Dinophyceae) from Jinhae-Masan Bay,Korea     

Eun Song Kim  Zhun Li  Seok Jin Oh  Yang Ho Yoon  Hyeon Ho Shin 《Ocean Science Journal》2017,52(3):427-437

Outbreaks of paralytic shellfish poisoning (PSP) and dense blooms caused by Alexandrium species in Jinhae-Masan Bay, Korea have been nearly annual events for many years. However, excluding some Alexandrium species responsible for PSP, there are no critical reports on the morphology of Alexandrium species in this bay. To identify the Alexandrium species based on detailed morphological features, vegetative cells collected water samples and established by the incubation of resting cysts isolated from sediment trap samples were analyzed. Four species of Alexandrium were identified: Alexandrium affine, A. fundyense, A. catenella, and A. insuetum. Morphological features of these species were basically consistent with those outlined in previous studies. However, the ventral pore and the connecting pore on the sulcal plate, which have been accepted as diagnostic characteristics for the identification of A. fundyense and A. catenella, need to be reevaluated, indicating that useful morphological features for identifying these two species should be recommended to avoid confusion in the classification of species in genus Alexandrium.  相似文献   

Quaternary Crustal Deformation in the Southeastern Part of the Korean Peninsula     

Bong Joo Lee  Chung-Ryul Ryoo  Deung-Lyong Cho  Sung-Ja Choi  Ueechan Chwae   《Gondwana Research》1999,2(4):578-582

  相似文献   

An Assessment of Deforestation Models for Reducing Emissions from Deforestation and Forest Degradation (REDD)     

Oh Seok Kim 《Transactions in GIS》2010,14(5):631-654

With the increasing concerns in developing methodologies for Reducing Emissions from Deforestation and forest Degradation (REDD) projects, there is a need to understand the characteristics of existing Land‐Use/Cover Change (LUCC) modules. This research presents a modular framework for assessing predictive accuracy of business‐as‐usual deforestation in the future by comparing two existing approaches: GEOMOD Modeling (GM) and Land Change Modeler (LCM). The comparison uses data from a case study in Chiquitanía, Bolivia. Data from 1986 and 1994 are used to simulate land‐cover of 2000; the resulting maps are compared with an observed land‐cover map of 2000. GM and LCM simulate business‐as‐usual deforestations at the pixel level. The model structures of GM's linear extrapolation and LCM's Markov Chain are compared to review quantity of LUCC; and the model structures of GM's empirical frequency, LCM's logistic regression, and LCM's multilayer perceptron are compared to review (spatial) allocation of LUCC. Relative operating characteristics, figure of merit, and multiple resolution analysis are employed to assess predictive accuracy of multiple transition modeling. By design, GM lacks the potential to model multiple transitions, and the LCM's multilayer perceptron may produce different results for each simulation due to its stochastic element. Based on the model structure and predictive accuracy comparisons, the LCM seems more suitable than the GM for a REDD application. When a project is to employ a predictive method for its spatially explicit baseline setting, then it is highly recommended to use the proposed framework to assess accuracy of the baseline as part of a project design document.  相似文献   

SHRIMP U–Pb zircon ages of the Hida metamorphic and plutonic rocks,Japan: Implications for late Paleozoic to Mesozoic tectonics around the Korean Peninsula          下载免费PDF全文

Yutaka Takahashi  Deung‐Lyong Cho  Jianren Mao  Xilin Zhao  Keewook Yi 《Island Arc》2018,27(1)

A new U–Pb zircon geochronological study for the Hida metamorphic and plutonic rocks from the Tateyama area in the Hida Mountains of north central Japan is presented. The U–Pb ages of metamorphic zircon grains with inherited/detrital cores in paragneisses suggest that a metamorphic event took place at around 235–250 Ma; the cores yield ages around 275 Ma, 300 Ma, 330 Ma, 1 850 Ma, and 2 650 Ma. New age data, together with geochronological and geological context of the Hida Belt, indicate that a sedimentary protolith of the paragneisses is younger than 275 Ma and was crystallized at around 235–250 Ma. Detrital ages support a model that the Hida Belt was located in the eastern margin of the North China Craton, which provided zircon grains from Paleoproterozoic to Paleozoic rocks and also from Archean and rare Neoproterozoic rocks. Triassic regional metamorphism possibly reflects collision between the North and South China Cratons.  相似文献   

Progressive change of tidal wave characteristics from the eastern Yellow Sea to the Asan Bay,a strongly convergent bay in the west coast of Korea     

Moon-Jin Park  Hubert H. G. Savenije  Huayang Cai  Eui Kyu Jee  Nam Hoon Kim 《Ocean Dynamics》2017,67(9):1137-1150

Although there have been studies on the tide in convergent bay (or estuary), the tide change in terms of phase speed, amplitude, and phase difference between elevation and tidal current from a coastal ocean to a convergent bay has not been clearly shown so far. This study systematically examines the change of tidal wave characteristics from the eastern Yellow Sea to the Asan Bay, a strongly convergent bay on the west coast of Korea, using observations and an analytical model. As the tidal wave propagates from the eastern Yellow Sea into the Asan Bay, the phase speed, amplitude, and phase difference between elevation and tidal current increase along the channel. Such a phenomenon represents a unique example of tide change from a coastal ocean to a convergent bay, indicating dominance of convergence over friction in the Asan Bay. Both analytically computed tidal amplitude and travelling time compare well with observations. In the Asan Bay, the influence of the reflected wave is only felt in the upper one fifth of the bay and is almost unperceivable in the rest of the bay. The analytical analyses presented in this paper are particularly useful for understanding the relative importance of channel convergence, bottom friction, and reflected wave on the tidal characteristics change along the channel and the proposed method could be applicable to other estuaries.  相似文献   

Evaluating the performance of climate models in reproducing the hydrological characteristics of rainfall events     

Jung-Hun Song  Satbyeol Shin  Jaepil Cho  Rajendra Paudel  Yogesh P. Khare 《水文科学杂志》2020,65(9):1490-1511

ABSTRACT

Rainfall events largely control hydrological processes occurring on and in the ground, but the performance of climate models in reproducing rainfall events has not been investigated enough to guide selection among the models when making hydrological projections. We proposed to compare the durations, intensities, and pause periods, as well as depths of rainfall events when assessing the accuracy of general circulation models (GCMs) in reproducing the hydrological characteristics of observed rainfall. We also compared the sizes of design storm events and the frequency and severity of drought to demonstrate the consequences of GCM selection. The results show that rainfall and extreme hydrological event projections could significantly vary depending on climate model selection and weather stations, suggesting the need for a careful and comprehensive evaluation of GCM in the hydrological analysis of climate change. The proposed methods are expected to help to improve the accuracy of future hydrological projections for water resources planning.  相似文献   

Ediacaran mafic magmatism recorded in Cambrian eclogites of the Ross orogen,Antarctica: Implications for the Neoproterozoic rifting episodes along the Pacific-Gondwana margin     

Taehwan Kim  Yoonsup Kim  Wonseok Cheong  Moonsup Cho  Jong Ik Lee 《地学学报》2023,35(1):32-40

We report the first finding of Ediacaran mafic magmatism in northern Victoria Land of the Ross orogen, Antarctica, based on ca. 600–590 Ma magmatic zircon cores in Cambrian eclogites. The mafic magmatism could be either linked to ca. 615–590 Ma incipient convergent margin magmatism in central segment of the Ross orogen, or ca. 600–580 Ma continental rift-related volcanism widespread in eastern Australia. The latter is preferred based on the trace-element compositions distinctive from those of arc-related basalts and the depleted mantle-like Hf isotopic compositions of zircon. Our results suggest dual rifting episodes during both the Ediacaran and Cryogenian (ca. 670–650 Ma) in the East Antarctic margin, correlative with those in eastern Australia. A spatial distribution of coeval rifting and subduction along the Ediacaran margin of East Antarctica is readily accounted for by rift inheritance; the upper- and lower-plate geometry resulting from detachment and transform faulting.  相似文献   

A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)     

Sangheon Yi  Chang-Gyun Han  Keun-Chang Oh  In Sun Seo  Dongwook Kim  Jaeyoung Lee  Min Han  Hanwoo Choi  Jaesoo Lim  Sujeong Park  Chang-Pyo Jun  Taesop Cho 《第四纪科学杂志》2022,37(1):100-113

We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ¹⁸O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.  相似文献