• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제10권S_4호
• /
• pp.197-206
• /
• 2001

The long-range transport mechanisms of Asian dust were analyzed based on the synoptic weather system and numerical simulation by using NCEP/NCAR reanalysis and TOMS data during the periods of 1996-2001. We classified the whole weather types of eastern Asia during spring and created the representative weather types during the yellow sand events using cluster analysis and weather charts for the last 6 years(1996~2001). These long-range transport mechanisms were related to various pressure patterns including high and low, trough and ridge, and upper-level fronts. Case studies of the yellow sand events have performed by the simulation of MM5 with meteorological elements such as the horizontal wind of u and v component, potential temperature, potential vorticity, and vertical circulation during the episodic days(2~8 March 2001). In addition, the origin of the long-range transport was examined with the estimation of backward trajectory using HYSPLIT4 Model. In this paper, we concluded that three weather types at 1000 hPa, 850 hPa, 500 hPa, and 300 hPa levels were classified respectively. The dominant features were the extending continental outflow from China to Korea at 1000 hPa and 850 hPa levels, the deep trough passage and cold advection at 500 hPa and 300 hPa levels during the yellow sand events. And also, we confirmed the existence of pola $r_tropical jets in the upper-level, the behavior of potential vorticity over Korea, the estimation of potential vorticity through vertical cross section, and the transport of yellow sand through backward trajectories.es.

• 한국토양비료학회지
• /
• 제42권3호
• /
• pp.160-166
• /
• 2009

We estimated site productivity for unstocked land based on the relationship between site index (i.e., average height of dominant trees at fixed age) and soil physico-chemical properties of Pinus densiflora stands. Site index relates to a direct method of determining a tree's response to a specific environment such as forest soil and climate conditions. We selected 78 sites in 22 P. densiflora stands of central temperate forest zone, and sampled soils for physicochemical analyzing. And 13 properties of soils were statistically treated by stepwise regression. In the degree of contribution of the variables to site index, the highly effective variables in A horizon were OM, clay content, sand content, available $P_2O_5$, and Exch. $Ca^{{+}{+}}$ inorder, and in B horizon T.N., O.M., Soil pH, cation exchange capacity(C.E.C.), and sand content in order. In both A and B horizon of the soil for P. densiflora stands, the variables commonly contributed to the site index were sand content and OM. These results may be useful to provide not only important criteria for establishment of Pinus densiflora stand sespecially in unstocked land but also aguidance for reforestation.

• 한국해양학회지:바다
• /
• 제1권1호
• /
• pp.32-45
• /
• 1996

광양만 동부해역의 퇴적과정의 변화를 이해하기 위하여 표층퇴적물 분포 및 시추코어에 대한 저서성 유공충 분석을 실시하였다. 사주지역에 대한 음향측심기를 이용한 결과 POSCO의 준설과 매립으로 인하여 해저지형이 변화되고 사주가 남동 방향으로 확대된 것으로 나타났다. 표층퇴적물의 분포는 섬진강 퇴적물 유입의 영 향을 받는 사주지역에서 사질퇴적상이 우세하고 만의 북동쪽으로 갈수록 세립한 퇴적양상을 보인다. 사주 경계 지역의 저서성 유공충 분포는 온대종인 Ammonia beccarii, Elphidium excavatum, Quinqueloculina lamarckiana우세하게 나타났으며 시추코어의 깊이별 유공충의 개체수 및 균등도의 변화가 적은 것으로 나타났다.

• Geosciences Journal
• /
• 제22권6호
• /
• pp.1027-1039
• /
• 2018

Seismic attributes are often used to identify lithology and evaluate reservoir properties. However, interpretation based only on structural attributes and without knowledge of the Vp/Vs ratio can limit the ability to evaluate changes in heavy oil reservoirs. These limitations are often due to less obvious impedance differences. In order to investigate pieces of evidence of a heavy-oil shaly-sand reservoir from seismic data, besides geochemistry, we studied seismic attributes and characterized the reservoir using seismic stack data and well logging data. The study area was the Muglad rift basin in South Sudan. We conducted a seismic complex analysis to evaluate the target reservoir. To delineate the frequency responses of the different lithological units, we applied the spectral decomposition method to the target reservoir. The most unexpected result was continuous bands of strong seismic reflectors in the target reservoir, which extended across the borehole. Spectral decomposition analysis showed that the low-frequency zone of 25 Hz dominant frequency was consistent with instantaneous attributes. This approach can identify lithology, reveal frequency anomalies, and filter the stacked section into low- and high-frequency bands. The heavy-oil reservoir zones exhibited velocity attenuation and the amplitude was strongly frequency dependent.

• 한국광물학회지
• /
• 제1권1호
• /
• pp.40-47
• /
• 1988

Mineralogy of sand, silt and clay fractions from the five chronosequence soils of Jeju Island is studied with the X-ray, TEM and SEM techniques. Soils of Songag and Donghong situated at lower elevations are generally developed on relatively of ash or alluvial deposits and contain mainly ferromagnesian minerals and feldspars, with some quartz, mica and volcanic glass. Crystalline minerals are dominant in the clay fraction; halloysite and vermiculite are abundant but small amounts of allophane are present. Clay migration results in well developed ferrigargillan, Soils of Pyeongdae and Heugag located at higher elevations are developed on relatively young volcanic ash with some contamination of continental aeolian dust probably containing quartz which may be come from acid ash shower. The absence of clay illuivation is due to the dominance of allophane. This clay mineral is associated with some gibbsite, imogolite and halloysite.

• 한국수산과학회지
• /
• 제37권5호
• /
• pp.423-432
• /
• 2004

In coastal area of Inchon, dredging and the disposal of dredged material for sea-wall construction and reclamation have increased in recent years. These activities may impact the benthic environment and result in changes in benthic communities, but little information is available on the extent and direction of these changes. We investigated whether there have been changes in the dominant macrobenthic species and benthic community over the last decade, and explored the relationship between environmental variables and spatial patterns of macrobenthic community structure. We sampled macrobenthos and recorded environmental variables in the coastal habitats of Inchon in March and June 2004. In total, 212 macrobenthic species were recorded during this study, predominately crustaceans $(34{\%})$, mollusks $(32{\%})$ and polychaetes $(21{\%})$. The mean density of macrobenthos was $1,393\;ind./m^{2}$.The most abundant species was Amphioplus japonicus $(20.5{\%})$, followed by Heteromastus filiformis $(14.4{\%})$, Theora fragilis $(8.2{\%})$ and Ampharete sp. $(4.0{\%})$. Over the past decade the dominant macrobenthic species in this area shifted. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among three regions: the middle part of the sampling area (B), site 8 (C) and other sites (A). Mean density varied significantly among the three regions, but no differences in the number of species and diversity (H') were observed. The distribution of the macrobenthic community was affected by environmental variables such as percentage sand content and sediment kurtosis. Species that were important in different areas included A. japonicus in region A, Raeta puchella in region B and T. fragilis in region C. The important species in regions B and C were filter-feeding bivalves, and the abundance of these species may be related to the increase in percentage sand content. We suggest that the sediment composition (percentage sand content) may be an important factor in determining the dominant species and structure of the macrobenthic communities in coastal Inchon. Long-term monitoring programs are necessary to understand ongoing changes in the benthic communities of this area.

• 환경생물
• /
• 제25권1호
• /
• pp.56-65
• /
• 2007

본 연구는 우이도 해안사구식생의 군락구분과 분포, 그리고 생육지 환경의 생태적 특성을 밝힘으로써 해안 사구식생의 관리, 보존 및 복원에 활용될 수 있는 기초자료를 제공하는데 그 목적이 있다. 조사는 Braun-Blanquet(1964)의 식물사회학적 방법에 의하여 실시하였다. 우이도의 사구식생은 순비기나무군락, 왕잔디군락, 보리사초군락, 갯쇠보리군락, 띠군락, 좀보리사초군락, 갯메꽃군락, 모래지치군락, 그리고 배후식생으로 상록침엽수림인 곰솔군락의 총 9개 군락으로 구분되었다. 사구식생을 구성하고 있는 식물들 중에서 갯메꽃(77%), 순비기나무(74%), 보리사초(66%), 왕잔디(50%), 띠(47%) 등의 상재도가 높게 나타났으며, 이 중 갯메꽃은 가장 높은 상재도에도 불구하고 각 군락내 절대기여도는 낮은 상태를 보였다. 사구식물의 분포와 생육 특성에서는 순비기나무, 보리사초, 왕잔디 등이 불안정사구에서 안정사구지가지 폭넓게 분포한데 반하여 갯쇠보리와 띠는 주로 안정사구지에서 군락을 형성하였다. 특히 보리사초는 모래의 퇴적이 계속되는 불안정사구지에서 우점 분포하였으며, 좀보리사초와 모래지치는 담수주변부에서 국지적으로 분포하였다.

• 지구물리
• /
• 제2권3호
• /
• pp.191-200
• /
• 1999

정밀 탄성파 탐사자료의 분석에 의하면 황해 중부의 퇴적환경은 크게 중국쪽 황하의 삼각주(delta) 환경, 황해 중심부의 침식대(erosional zone), 그리고 한국쪽의 모래퇴(sand ridge) 및 모래파(sand wave) 환경으로 뚜렷하게 구분된다. 중국 황하 말단부에서는 전진퇴적 양상의 삼각주 전면(delta front)에서 점진적으로 전위삼각주(prodelta)로 변한다. 삼각주 퇴적물들은 황해 중심부로 이동하지 못하고, 대부분이 산동반도를 돌아서 남하한다. 황해 중심부에 발달한 침식대에서는 북서-남동 방향으로 발달한 다수의 해저수로들과 불규칙한 형태의 침식면이 관찰된다. 이 해역의 일부에서는 선현세 산화대층이 해저면에 노출되어 있는데, 홀로세 동안에 퇴적물의 집적보다는 무퇴적 또는 침식작용이 우세하였음을 지시한다. 한국측 주변 해역에서는 규칙적인 배열 및 형태를 갖는 모래퇴 또는 모래파들이 발달되어 있다. 이 모래질 퇴적물들은 대부분이 저해수면 시기에 하천으로부터 공급된 퇴적물로서 해수면이 다시 상승할 때 재동·잔류된 것으로 해석된다. 현생 모래퇴들은 북동-남서 방향으로 배열되어 있는데, 이것은 조류의 영향에 의한 것으로 해석된다.

• The Korean Journal of Ecology
• /
• 제14권4호
• /
• pp.457-467
• /
• 1991

Occurrence and distribution of the celluar slime molds in relation to the coastal plant communities of svven islands near inch'on wereinvestigated. as a results, total seven species were isolated from the soils of the coastal plant communities. These are dictyostelium mucoroides, polysphodylium pallidum, dictystelium polycephalum. d. mucoroides was the most commonly found in the coastal plant communities investigated, and was dominant pecularly in the coastal mixed forests, the coastal broad-leaved forests and salt marshes. In the coastal coniferous forest and the coastal dune sand plants, hoeever, p. violaceum was the dominant species. species diversity was relatively was relatively high in the coastal coniferous ferests and the coastal mixed forests. However, agerage number of species isolated from all plant communities was very low,2.8.

• 한국대기환경학회지
• /
• 제10권2호
• /
• pp.124-129
• /
• 1994

Aerosol size distribution was determined using Anderson sampler for the anions( sulfate nitrate and chloride ) and TSP. Ionic species concentration and size distribution have been investigated in the daytime and nightime individually. Size classified samples were extracted with distilled water and analyzed for C $l^{[-10]}$ , N $O_3$$^{[-10]}$ and S $O_4$$^{2-}$, by ion chromatography. The size distribution of these ions and TSP was analyzed to investigate the seasonal and diurnal variation of concentrations as follows: (1)Size distribution of TSP showed bi- modal type in the daytime, but indicated tri-mode distribution in the nightime without any seasonal variation. (2)Sulfate concentrations were higher in fine- mode both in the daytime and nightime but fraction of sulfate was higher in coarse-mode during the Yellow Sand Period. (3)Nitrate and Chloride ions are dominant in fine-mode in winter while dominant in coarse-mode in the summer.