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排序方式: 共有260条查询结果,搜索用时 46 毫秒
1.
To use two small fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and the Japanese medaka Oryzias latipes (Belloniformes) as testing models in molecular ecotoxicology, we have cloned the cytochrome P450 1A (CYP1A) gene after screening of both genomic DNA libraries, and sequenced 11,863 and 7,243 bp including all the exons and introns with promoter regions, respectively. The Rivulus and the medaka CYP1A gene consisted of seven exons (including non-coding exons) with high homology to mammals. In the promoter region, Rivulus CYP1A gene has seven xenobiotic response elements (XREs) and two metal response elements (MREs), while the Japanese medaka CYP1A gene has six XREs and four MREs. Interestingly, medaka CYP1A gene has a number of MREs at the promoter, which may affect its response on metal exposure. We describe here the gene structure of both fish CYP1A genes. 相似文献
2.
Ho Il Yoon Myung Woo Han Byong-Kwon Park Jae-Kyung Oh Soon-Keun Chang 《Marine Geology》1997,140(3-4):265-282
High-resolution (3.5 kHz and multi-channel) seismic profiles and piston cores were collected from Maxwell Bay and its tributary embayment, Marian Cove, in the South Shetland Islands, Antarctica, during the Korea Antarctic Research Program (1992/93 and 1995/96) to elucidate the glaciomarine sedimentation processes and recent glacial history of the area. Seismic data from Maxwell Bay reveal a rugged bay margin and flattened basin floor covered with well-stratified hemipelagic muds. On the base-of-slope, acoustically transparent debris flows occur, indicating downslope resedimentation of glaciomarine sediments. Despite the subpolar and ice-proximal settings of Marian Cove, the seafloor is highly rugged with a thin sediment drape, suggesting that much of the area has been recently eroded by glaciers. Sediment cores from the cove penetrated three distinct fining-upward lithofacies: (1) basal till in the lower part of the core, accumulated just seaward of the grounding line of the tidewater glacier; (2) interlaminated sand and mud in the middle part, deposited in ice-proximal zone by a combination of episodic subglacial meltwater inflow and iceberg dumping; and (3) pebbly mud in the upper part, deposited in ice-distal zone by both surface meltwater plume and ice-rafting from the glacier front. A reconstruction of the glacial history of these areas since the late glacial maximum shows an ice sheet filling Maxwell Bay in late Wisconsin time and grounding of the tidewater glacier in Marian Cove until about 1300 yr BP. 相似文献
3.
In order to clarify the formation and circulation of the Japan/East Sea Intermediate Water (JESIW) and the Upper portion of
the Japan Sea Proper Water (UJSPW), numerical experiments have been carried out using a 3-D ocean circulation model. The UJSPW
is formed in the region southeast off Vladivostok between 41°N and 42°N west of 136°E. Taking the coastal orography near Vladivostok
into account, the formation of the UJSPW results from the deep water convection in winter which is generated by the orchestration
of fresh water supplied from the Amur River and saline water from the Tsushima Warm Current under very cold conditions. The
UJSPW formed is advected by the current at depth near the bottom of the convection and penetrates into the layer below the
JESIW. The origin of the JESIW is the low salinity coastal water along the Russian coast originated by the fresh water from
the Amur River. The coastal low salinity water is advected by the current system in the northwestern Japan Sea and penetrates
into the subsurface below the Tsushima Warm Current region forming a subsurface salinity minimum layer.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Major variations in type and rate of tectonic movement in the southwestern margin of the Ulleung Basin coincide in time with
changes in stratal patterns at succession boundaries, suggesting that the effect of tectonism was dominant for the development
of sequence architecture. During the back-arc opening (16–12 Ma), the rise of relative sea level and the high rate of sediment
supply gave rise to sequences with sigmoid progradational patterns. During the back-arc closing (12–6.5 Ma), fall- and rise-dominated
relative sea-level fluctuations resulted in sequences with varying stratal patterns depending upon changes in deposition rate.
The rise-dominated relative sea level has been prevalent during the later stage (6.5 Ma–Present) with low sedimentation rate.
Received: 16 January 1996 / Revision received: 7 February 1997 相似文献
5.
Robust diagnostic modeling of the Japan Sea circulation 总被引:1,自引:0,他引:1
The Japan Sea circulation is numerically modeled with robust diagnostic terms included. The general features are nearly the same as previous prognostic models though small differences appear in local current fields, and agree with most of existing observation results. This model, however, seems to be more successful than prognostic ones in that the overshooting of the East Korean Warm Current, a northward western boundary current, is much reduced and the North Korean Cold Current, a southward western boundary current, is more enhanced. Based on the model results, discussions are made about the large convective structure and the global kinetic energy budget of the Japan Sea circulation. 相似文献
6.
Species composition and spatial distribution of euphausiids of the yellow sea and relationships with environmental factors 总被引:1,自引:0,他引:1
Won Duk Yoon Joon Yong Yang Donghyun Lim Sung Hwan Cho Gyung Soo Park 《Ocean Science Journal》2006,41(1):11-29
We investigated species composition and spatial distribution of the euphausiid community in the Yellow Sea and identified
the relationship with environmental factors (temperature, salinity, chlorophyll a, nitrate, phosphate, and silicate) using
bimonthly data from June, 1997 to April, 1998. The environment varied during the sampling period. In warm seasons, thermocline
was well developed rendering lower temperature and higher salinity and nutrient concentrations in the bottom layer. During
cold seasons the water column was well mixed and no such vertical stratification was noted. Horizontal distribution of temperature,
however, differed slightly between near-coast and offshore areas because of the shallow depth of the Yellow Sea, and between
southern and northern areas because of the intrusion of water masses such as Yellow Sea Warm Current and Changjiang River
Diluted Water. Four euphausiid species were identified:Euphausia pacifica, E. sanzoi, Pseudeuphausia sp. andStylocheron affine. E. sanzoi andS. affine were collected, just one juvenile each, from the southern area in June and December, respectively.Pseudeuphausia sp. were collected in the eastern area all the year round except June.E. pacifica occurred at the whole study area and were the predominant species, representing at least 97.6% of the euphausiid abundance.
Further, the distribution pattern of the species was varied in regards to developmental stages (adult, furcilia, calyptopis,
egg). From spring to fall,E. pacifica adults were abundant in the central area where the Yellow Sea Bottom Cold Water prevailed. Furcilia and calyptopis extended
their distribution into nearly all the study area during the same period. From late fall to winter, adults were found at the
near-coastal area with similar pattern for furcilia and calyptopis. The distribution pattern ofE. pacifica was consistent regarding temperature, salinity, and three nutrients during the sampling period, whereas chlorophyll a showed
a different pattern according to the developmental stages. The nutrients should indirectly affect via chlorophyll a and phytoplankton
concentration. With respect to these results, we presented a scenario about how the environmental factors along with the water
current affect the distribution ofE. pacifica in the Yellow Sea. 相似文献
7.
Jin-Yong Lee Jeong-Yong Cheon Hyung-Pyo Kwon Hee-Sung Yoon Seong-Sun Lee Jong-Ho Kim Joung-Ku Park Chang-Gyun Kim 《Environmental Geology》2006,51(4):581-593
Attenuation characteristics of landfill leachate were examined for two uncontrolled landfills in Korea. The two landfills containing municipal wastes without appropriate bottom liner and leachate treatment system have different landfill age, waste volume, and most importantly different hydrogeologic settings. One landfill (Cheonan landfill) is situated in an open flat area while the other (Wonju landfill) is located in a valley. Variations of various parameters including dissolved organic carbon (DOC), dissolved oxygen (DO), alkalinity, pH, electrical conductivity (EC), redox potential (ORP), ammonia (NH3), nitrate (NO3−), sulfate (SO42−), and chloride (Cl−) were examined along groundwater flow path. All these parameters were analyzed every month for a year. In the interior of the landfills, typical anaerobic conditions revealed by low DO and NO3 concentrations, negative ORP values, high NH3, alkalinity, and Cl− concentrations were observed. Generally, higher levels of contaminants (DOC, NH3, and Cl−) were detected in the dry season while they were greatly lowered in the wet season. Significantly, large decrease of Cl- concentration in the wet season indicates that the dilution or mixing is one of dominant attenuation mechanisms of leachate. But detailed variation behaviors in the two landfills are different and they were largely dependent on permeability of surface and subsurface layers. The intermediately permeable surface of the landfills receives part of direct rainfall infiltration but most rainwater is lost to fast runoff. The practically impermeable surface of clayey silt (paddy field) at immediately adjacent to the Cheonan landfill boundary prevented direct rainwater infiltration and hence redox condition of the ground waters were largely affected by that of the upper landfill and the less permeable materials beneath the paddy fields prohibited dispersion of the landfill leachate into down gradient area. In the Wonju landfill, there are three different permeability divisions, the landfill region, the sandy open field and the paddy field. Roles of the landfill and paddy regions are very similar to those at the Cheonan. The very permeable sandy field receiving a large amount of rainwater infiltration plays a key role in controlling redox condition of the down gradient area and contaminant migration. This paper reports details of the attenuation and redox conditions of the landfill leachates at the two uncontrolled landfills. 相似文献
8.
9.
Core A9-EB2 from the eastern Bransfield Basin, Antarctic Peninsula, consists of pelagic (diatom ooze-clay couplets and bioturbated diatom ooze) and hemipelagic (bioturbated mud) sediments interbedded with turbidites (homogeneous mud and silt–clay couplets). The cyclic and laminated nature of these pelagic sediments represents alternation between the deposition of diatom-rich biogenic sediments and of terrigenous sediments. Sediment properties and geochemical data explain the contrasting lamination, with light layers being finer-grained and relatively rich in total organic carbon and biogenic silica content. Also, the high-resolution magnetic susceptibility (MS) variations highlight distinct features: high MS values coincide with clastic-rich sections and low MS values correspond to biogenic sections. The chronology developed for core A9-EB2 accounts for anomalous ages associated with turbidites and shows a linear sedimentation rate of approximately 87 cm/103 yr, which is supported by an accumulation rate of 80 cm/103 yr calculated from 210Pb activity. The late Holocene records clearly identify Neoglacial events of the Little Ice Age (LIA) and Medieval Warm Period (MWP). Other unexplained climatic events comparable in duration and amplitude to the LIA and MWP events also appear in the MS record, suggesting intrinsically unstable climatic conditions during the late Holocene in the Bransfield Basin of Antarctic Peninsula. 相似文献
10.
Tai Ho Choo Soo Kwon Chae Hyeon Cheol Yoon Yeon Moon Choo 《Environmental Earth Sciences》2014,71(2):675-683
Discharge is an important factor in river design for water utilization, water control and hydraulic structures; therefore, an accurate estimation of the discharge is required. At present, a rating curve depicting the relationship between a stage and discharge is used to calculate the discharge from river systems. Although the rating curve has an advantage in that it can predict and use the discharge during the flood season in which the measurement is difficult, there is room for improvement as it does not reflect the hydraulic characteristics of rivers. Therefore, in this study, discharge was predicted using the convenient calculation method with empirical mediating variables of the Manning and Chezy equations which were proposed by the author’s previous research as a new methodology for estimating discharge in an open channel. This was proven, based on the data measured in a meandering open channel system in a lab at the Mississippi River in the US and at the Columbia Del Dique Canal, and an accuracy level at a coefficient of 0.8 was demonstrated. Thus, this method, which reflects the hydraulic characteristics and predicts the discharge in a simple manner, is expected to be convenient in practice. 相似文献