• Ocean and Polar Research
• /
• 제31권4호
• /
• pp.297-304
• /
• 2009

We investigated the response of the westerly winds over the Southern Ocean (SO) to glacial boundary conditions for the Last Glacial Maximum using the CCM3 atmospheric general circulation model. In response to glacial boundary conditions, the zonally averaged maximum SO westerly winds weakened 20-35% and were displaced toward the equator by 3-4 degrees. This weakening of the SO westerly winds arose from a substantial increase in mean sea level pressure (MSLP) in the southern part of the SO around Antarctica relative to the northern part. The increase in MSLP around Antarctica is associated with a marked temperature reduction caused by an increase in sea ice cover and ice albedo feedback during the glacial time. The weakened westerly winds in the SO and their equator-ward displacement might play a role in reducing the atmospheric $CO_2$ concentration by reducing upwelling of the carbon rich deep water during the glacial time.

• Ocean and Polar Research
• /
• 제24권2호
• /
• pp.167-175
• /
• 2002

Sediment from six piston cores from the East Sea (Sea of Japan) was analyzed for evidence of paleoceanographic changes and paleoclimatic variation. A distinct geochemical boundary is evident in major element concentrations and organic carbon content of most cores near the 10-ka horizon. This distinctive basal Holocene change is interpreted to be largely the result of changing sediment sources, an interpretation supported by TiO_2/Al_2O_3$ ratios. Organic carbon and carbonate contents also differ significantly between the Holocene and glacial intervals. The C/N ratio of organic matter is greater than 10 during the glacial period, but is less than 10 for the Holocene, suggesting that the influx of terrigenous organic matter was more volumetrically important than marine organic matter during glacial times. The chemical index of weathering (CIW) is higher for the Holocene than the glacial interval, and changes markedly at the basal Holocene geochemical boundary. Silt fractions are higher in the glacial interval, suggesting a strong effect of climate on silt particle transportation: terrigenous aluminosilicates and continental organic carbon transport were higher during glacial times than during the Holocene. Differences in sediment composition between the Holocene and glacial period are interpreted to have been climatically induced.

• Mass Spectrometry Letters
• /
• 제12권4호
• /
• pp.192-199
• /
• 2021

Alpine glaciers harbor a large quantity of bio-labile dissolved organic matter (DOM), which plays a pivotal role in global carbon cycling as glacial-fed streams are headwaters of numerous large rivers. To understand the complexity, origin, and fate of DOM in glaciers and downstream-linked streams and lakes, we elucidated the molecular composition of DOM in two different Tibetan Plateau glaciers, eight glacial-fed streams and five lakes, using an ultrahigh-resolution 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The compositional changes of the DOM samples revealed that glacier DOM mostly exhibited sulfur-containing organic compounds (CHOS species). We also found that aliphatic formulae contributed more than 50% of the total abundance of assigned molecules in glacier samples, and those compounds were significantly related to CHOS species. The CHO proportions of glacial-fed streams and lakes samples increased with increasing distance from glacial terminals. The relative contribution of terrestrial-derived organics (i.e., lignins and tannins) declined while microbial-originated organics (aliphatics) increased with increasing elevation. This suggested the gradual input of allochthonous materials from non-glacial environment and the degradation of microbe-derived compounds along lower elevations. Alpine glaciers are retreating as a result of climate change and they nourished numerous streams, rivers, and downstream-linked lakes. Therefore, the interpretations of the detailed molecular changes in glacier ice, glacial-fed streams, and alpine lakes on the Tibetan Plateau could provide broad insights for understanding the biogeochemical cycling of glacial DOM and assessing how the nature of DOM impacts fluvial ecosystems.

• 식물분류학회지
• /
• 제46권4호
• /
• pp.337-347
• /
• 2016

Based on genetic studies and palaeoecological surveys, the main Korean mountain range, the so-called "Baekdudaegan" (BDDG), has been recently suggested to be a major glacial refugium at the Last Glacial Maximum (LGM) for the boreal and temperate flora of northeastern Asia. On the basis of its shared role as a glacial refugium, and on a series of striking similarities in floristic richness and orographic features, the BDDG would constitute a sort of "eastern counterpart" of the Southern Appalachians. Given its floristic, biogeographic, and cultural value, the BDDG merits high priority for conservation.

• 대한원격탐사학회지
• /
• 제27권5호
• /
• pp.543-553
• /
• 2011

Aqua에 탑재된 AMSR-E는 NASA Team2 해빙 알고리즘을 사용하여 해밍 면적비를 계산하고 있으며, 이는 남극의 해빙 지역에서 매우 정확하다는 것이 증명되었다. 그러나 AMSR-E의 관측 영역 내에 빙산 및 빙붕과 같은 빙하빙이 많이 포함될 경우 해빙과는 다른 빙하빙의 복사특성 때문에 NASA Team2알고리즘으로부터 계산되는 얼음의 면적비는 그 정확성이 유지되지 않는다. 본 논문에서는 남극의 George V 해안이 촬영된 두 장의 ENVISAT ASAR 영상으로부터 해빙과 빙하빙의 면적비를 추출하였고, 이를 NASA Team2 해빙 면적비와 비교하였다. NASA Team2 알고리즘은 빙하빙에 대해 실제보다 작은 면적비를 계산하였다. 빙하빙에 대한 NASA Team2 알고리즘의 면적비 계산 오류를 해석하기 위해 PR(polarization ratio), GR(spectral gradient ratio), $PR_R$(rotated PR), 그리고 ${\Delta}GR$ 영역에서 빙하빙의 마이크로파 복사특성을 분석하였다. 빙하빙은 PR, GR, $PR_R$, ${\Delta}GR$ 영역에서 ice type A, B, C와 같은 남극의 해빙 및 open water와 구분되는 고유한 범위를 형성하였으며, 이는 빙하빙이 얼음의 새로운 종류로 AMSR-ENASA Team2 해빙 알고리즘에 추가될 수 있음을 의미한다.

• Journal of the korean society of oceanography
• /
• 제35권2호
• /
• pp.98-108
• /
• 2000

A geochemical study on a hemipelagic core sediment taken from the northwest Pacific Ocean (eastern edge of the Shikoku Basin) was conducted to use of excess barium (Ba(ex)) for evaluate the paleoceano-graphic changes. Also, the excursion of sedimentary Ba(ex) was compared with those of biogenic opal, carbonate and organic carbon content in the sediment during the last glacial and interglacial periods. The calculated Ba(ex) derived from the major and minor element shows a distinctive glacial-interglacial variations, and the mass accumulation rate (MAR) of Ba(ex) shows coincident variations with the MARs of biogenic fractions. Especially, strong positive correlation (r$^2$=0.85) between the MAR of Ba(ex) and the MAR of biogenic carbonate is recognized. Based on the strong positive correlation(r$^2$=0.85) between the MAR of Ba(ex) and the MAR of carbonate content, we estimated the degree of carbonate dissolution rate during the glacial and interglacial periods. Assuming the proportional variation and the refractory nature of barium exist between two factors, the variation of index Ca/Ba ratio in sediment indicates the degree of carbonate dissolution. Sedimentary Ca/Ba ratios index clearly show a striking fluctuation between the glacial and interglacial periods with higher positive correlation during glacial and lower correlation during interglacial. This fact indicates enhanced carbonate dissolution during interglacial period. Thus, the sedimentary Ca/Ba ratio in sedimentary records can be used as one of the useful tools for estimation of the relative degree of carbonate dissolution. The excursion of Ba(ex) and the sedimentary Ca/Ba ratio follows the typical pacific carbonate dissolution type(enhanced dissolution during interglacial and reduced dissolution during glacial time) as suggested by previous work (e.g., Wu et al., 1990). Variation in sedimentary Ca/Ba ratio thus strongly supports that glacial-interglacial fluctuation in carbonate dissolution has been prevailed in the northwest Pacific Ocean.

• 생명과학회지
• /
• 제13권6호
• /
• pp.836-842
• /
• 2003

1,2-phenylenediamino과 2,5-dimethoxytetrahydro- furan을 빙초산 용매하에서 1-(2-aminophenyl)- pyrrole 5를 합성하였다. 1,3-phenylenediamine과 2,5-dimethoxytetrahydrofuran을 빙초산을 사용하여 1-(3-aminophenyl)pyrrole 7과 1,3-dipyrrolyl-benzene 8을 합성하였다. 1,4-phenyl-enediamine과 2,5-dimethoxytetrahydrofuran을 빙초산을 사용하여 1,4-dipyrrolylbenzene 10을 합성하였다. 1,2-phenylenediamine, 1,3-phenylenediamine 그리고 1,4-phenyl-enediamine과 2,5-dimethoxytetra- hydrofuran을 (가) 빙초산 대신, (나) 용매없이, (다) acrylic acid, (라) silica gel, (마) acrylic acid와 silicagel, 그리고 (바) silica gel과 acetic acid를 사용하여 각각 반응시켜 그에 상응하는 amino-phenylpyrroles 5, 7과 dipyrrolylbenzenes 8, 10을 합성하였다. 여러 가지 방법 중 (마) silicagel과 acetic acid를 사용한 경우에 dipyrrolylbenzenes 8, 10의 합성에 관한 반응성이 가장 좋았다. 또한 dicarbazolylbenzene을 합성하기 위한 전단계로 9-phenylcarbazole 11을 합성하였다.

• Geomechanics and Engineering
• /
• 제28권4호
• /
• pp.375-384
• /
• 2022

The glacial tills and shales in Midwestern states of the USA often show strength degradation after construction. They are often in need of applying soil modification techniques to remediate their strength degradation with weathering process. This study investigated the weathering durability of these natural soils and biopolymer treated soils by comparing direct shear test results for wet-dry and wet-freeze-thaw-dry cycled specimens. The tests showed that untreated glacial tills maintained only 62% and 50% initial shear strength after eight wet-dry cycles and eight wet-freeze-thaw-dry cycles, respectively. These untreated soils could not withstand by themselves after 16 weathering cycles. The same soils treated with 1.5% (by dry weight) food-grade Xanthan gum maintained 140% and 88% initial shear strength of untreated soils after 16 weathering cycles for wet-dry cycles and wet-freeze-thaw-dry cycles, respectively. The same soils treated with 1.5% (by dry weight) Gellan gum maintained 82% and 60% initial shear strength of untreated ones after 16 weathering cycles, respectively. Similar results were obtained for crushed shales, manifesting that the biopolymerization method may be adopted as a new eco-friendly method to enhance the weathering durability of these problematic soils of glacial tills and shales.

• 대한임상독성학회지
• /
• 제10권2호
• /
• pp.91-96
• /
• 2012

Purpose: A retrospective study with a literature review was conducted to identify the clinical characteristics and prognosis after the acute ingestion of glacial acetic acid. Methods: The medical records of 20 patients,who had presented to the emergency department of Ajou University Hospital complaining of the acute ingestion of glacial acetic acid between January 2006 and December 2011, were examined retrospectively. Results: Among the 172 patients admitted for caustics injury, 20 patients ingested glacial acetic acid. The mean age of the patients was $55{\pm}23.5$, and the mean volume of the acid was $84.5{\pm}71.3$ ml. The clinical features included 1) oral ulcers in 12 patients (63.2%), 2) respiratory difficulties in 11 patients (57.9%), 3) oliguria in 8 patients (42.1%), 4) renal toxicity in 7 patients (36.8%), 5) hepatic failure in 7 patients (36.8%), 6) disseminated intravascular boagulopathyin 7 patients (36.8%), 7) low blood pressure in 8 patients (42.1%), and 8) mental changes in 9 patients (47.4%). Ten patients required endotracheal intubation. Nine patients were admitted to the intensive care unit, and 5 patients expired. Conclusion: The ingestion of glacial acetic acid can cause severe symptoms, such as metabolic acidosis, multiple organ failure and upper airway swelling frequently and has a high mortality rate. Therefore, aggressive treatment, including endotracheal intubation, should be considered at the early stages.

• 한국해양학회지:바다
• /
• 제6권2호
• /
• pp.71-80
• /
• 2001

최종빙기와 흘로세 사이의 전이기에 일어난 동해의 고해양환경 변화를 이해하기 위하여 울릉분지 최남단 대륙사면에서 얻어진 주상시료(95PC-1)퇴적물에 대한 지화학적 고분해 연구를 하였다. 지화학적 결과는 주요 고행양학적변화가 이 전이기에 뚜렷하게 일어나고 있음을 밝히고 있다. 주요원소를 분석한 결과 최종빙기와 홀로세 사이에 뚜렷한 퇴적물의 조성변화를 보이고 있으며 이는 퇴적물의 공급변화가 수반되었음을 지시하고 있다. 퇴적물 중의 $TiO_2/Al_2O_3$는 흘로세와 최종빙기의 퇴적물 조성이 다름을 지시하고 있다. 유기탄소 함량도 약 $0.5{\sim}4%$ 정도의 폭으로 변화하고 있으며 이러한 변화는 평균적인 최종빙기와 간빙기(흘로세)의 값과 비교했을 때 각각 $2{\sim}4$배, 2배 정도 증가하여 전이기에 생물생산이 증가한 것임을 알 수 있다. 대륙기원 유기물의 유입을 지시하는 C/N비도 이 전이기를 중심으로 10이상을 보이고 있어 유기물이 인근 대륙으로부터 유입되었음을 지시하고 있으며, 특히 최종빙기 동안에는 활발하게 대륙으로부터 유기물이 유입되었음을 알 수 있다. 탄산염 함량변화는 흘로세 기간동안에는 비교적 안정하여 약 2.5%전후의 값을 보이고 있다가 전이기에 큰 폭의 변화를 보이면서 최종빙기에는 점진적으로 감소하는 경향을 보이고 있다. 퇴적물의 화학원소에 근거한 풍화지수(CIW)를 조사해본 결과 약 1만년을 경계로 뚜렷하게 변화하고 있으며 이러한 점은 유기물과 탄산염에 나타난 전이기와 잘 일치하고 있다. 입도분석 결과 나타난 최종빙기와 흘로세 간의 실트질 퇴적물의 함량차이는 빙기동안에 강해진 기후요소와 밀접히 관계되는 것으로 생각된다. 따라서 전이기에 나타나는 지화학적 기록변화는 해수면 상승과 결부된 해양환경변화 및 지역적인 기후변동과도 밀접히 관계되고 있음을 지시한다.