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News Article | August 30, 2016
Site: http://www.chromatographytechniques.com/rss-feeds/all/rss.xml/all

Historic changes to Antarctic sea ice could be unraveled using a new technique pioneered by scientists at Plymouth University. It could also potentially be used to demonstrate past alterations to glaciers and ice shelves caused by climatic changes, a study published in Nature Communications suggests. The new method builds on an existing technique, also developed by Plymouth University over the last 10 years, which identified a means by which scientists could measure changes to sea ice in the Arctic. That has already led scientists to reveal periods when the Arctic was previously ice free during summers, and when sea ice first expanded to is modern extent. "In addition to allowing us to unlock historical changes to Antarctic sea ice, our new method also has the potential to provide further insights into other critical climatic features that may have changed in the past. Indeed, sea ice around the Antarctic coastline is strongly influenced by nearby glaciers and ice shelves, both of which contribute to increased global sea level when they melt. Therefore, our new approach may also permit a much broader spectrum of climatic changes to be unraveled in the future," said Simon Belt, professor of chemistry at Plymouth University and lead author on the study. The previous technique is based on the presence of IP25 (ice proxy with 25 carbon atoms), a lipid chemical made solely by microalgae that live in the bottom of Arctic sea ice. When the ice melts, the algae and its lipids fall into the sediments that can be recovered, dated and analyzed. IP25 does not exist in the Antarctic, but scientists from Plymouth - working with colleagues from Hanyang University, the Korea Polar Research Institute, the British Antarctic Survey and Isoprime Limited - have discovered a related chemical in the Southern Ocean. Analysis of surface sediments covering different regions of Antarctica - including the Weddell Sea, the Antarctic Peninsula, the Bellingshausen Sea and the Ross Sea - showed the presence of IPSO25 (ice proxy for the Southern Ocean with 25 carbon atoms) in nearly all cases. Its source, Berkeleya adeliensis, is a widespread and commonly occurring constituent of microalgae inhabiting Antarctic sea ice, which explains why IPSO25 is so common in the sediments. "The identification of IPSO25 in the Antarctic sea ice diatom Berkeleya adeliensis likely ensures that future interpretations of the sedimentary occurrence of this sea ice proxy can be made with greater confidence and in more detail. Thus, in addition to representing a qualitative measure of the past occurrence of Antarctic landfast ice during late spring/summer, our findings indicate that variability in sedimentary IPSO25 potentially provides further insights into changes to ice shelf and glacial melt processes in long-term records," the paper concludes.


Notothenia coriiceps, a typical Antarctic notothenioid teleost, has evolved to adapt to the extreme Antarctic marine environment. We previously reported an extensive analysis of the Antarctic notothenioid transcriptome. In this study, we focused on a key component of the innate immune system, the Toll-like receptors (TLRs). We cloned the full-length sequence of 12 TLRs of N. coriiceps. The N. coriiceps transcriptome for TLR homologue (ncTLR) genes encode a typical TLR structure, with multiple extracellular leucine-rich regions and an intracellular Toll/IL-1 receptor (TIR) domain. Using phylogenetic analysis, we established that all of the cloned ncTLR genes could be classified into the same orthologous clade with other teleost TLRs. ncTLRs were widely expressed in various organs, with the highest expression levels observed in immune-related tissues, such as the skin, spleen, and kidney. A subset of the ncTLR genes was expressed at higher levels in fish exposed to pathogen-mimicking agonists, heat-killed Escherichia coli, and polyinosinic-polycytidylic acid (poly(I:C)). However, the mechanism involved in the upregulation of TLR expression following pathogen exposure in fish is currently unknown. Further research is required to elucidate these mechanisms and to thereby increase our understanding of vertebrate immune system evolution. Source


Kim S.-Y.,Korea Polar Research Institute | Lim D.-I.,Korea Advanced Institute of Science and Technology
Progress in Oceanography | Year: 2014

Marine microfossil assemblages in core sediments from the northern East China Sea (ECS) were investigated to understand late Holocene paleoclimatic changes in the northwestern Pacific margin. We find a pronounced alternation of ocean condition during the late Holocene characterized by an abrupt decrease in dinoflagellate cysts and Kuroshio water species of planktonic foraminifera centered at ca. 4000-2500 14C yr BP. Compilation and merger of new and previously published data show that this oceanic event corresponds with terrestrial cooling and dry episodes in the northern China. The synchronicity between marine and terrestrial records is considered to be linked to a weakened Kuroshio influence that is in coupled with intensified winter monsoon, highlighting a significance of oceanic-atmospheric dynamics in determining moisture and heat distribution over both oceanic and terrestrial domains. Superimposed on the late Holocene, the synchronicity between this particular climatic shift in the northwestern Pacific and the Neoglacial cold events in the northern high-latitude regions is tentatively indicative of a global climate signal, possibly associated with dynamics of the North Pacific gyre system and the high latitude North Atlantic thermohaline circulation, and therefore positions of the mean latitude of the Kuroshio extension. © 2014 Elsevier Ltd. Source


Kim Y.,Seoul National University | Kim K.-Y.,Seoul National University | Kim B.-M.,Korea Polar Research Institute
Climate Dynamics | Year: 2013

Annual snow cover in the Northern Hemisphere has decreased in the past two decades, an effect associated with global warming. The regional scale changes of snow cover during winter, however, vary significantly from one region to another. In the present study, snow cover variability over Europe and its connection to other atmospheric variables was investigated using Cyclostationary Empirical Orthogonal Function (CSEOF) analysis. The evolution of atmospheric variables related to each CSEOF mode of snow cover variability was derived via regression analysis in CSEOF space. CSEOF analysis clearly shows that the North Atlantic Oscillation (NAO) is related to European snow cover, particularly in January and February. A negative NAO phase tends to result in a snow cover increases, whereas a positive NAO phase results in snow cover decreases. The temporal changes in the connection between the NAO and European snow cover are explained by time-dependent NAO-related temperature anomalies. If the NAO phase is negative, the temperature is lower in Europe and snow cover increases; by contrast, when the NAO phase is positive, the temperature is higher and snow cover decreases. Temperature and snow cover variations in Europe are associated with the thermal advection by anomalous wind by NAO. CSEOF analysis also shows an abrupt increase of snow cover in December and January and a decrease in February and March since the year 2000, approximately. This abrupt change is associated with sub-seasonal variations of atmospheric circulation in the study region. © 2012 Springer-Verlag. Source


Kim B.-M.,Korea Polar Research Institute | An S.-I.,Yonsei University
Journal of Climate | Year: 2011

The regime behavior of the low-order El Niño-Southern Oscillation (ENSO) model, according to an increase in the radiative-convective equilibrium sea surface temperature (SST; Tr), is studied to provide a possible explanation for the observed increase in ENSO irregularity characterized by decadal modulation. During recent decades, a clear increasing trend of the warm-pool SST has been observed. In this study, the increase in the warm-pool maximum SST is interpreted as an increase in Tr following previous studies. A bifurcation analysis with Tr as a control parameter is conducted to reveal that the degree of ENSO irregularity in the model is effectively controlled by the equilibrium states of the model. At a critical value of Tr, bifurcation analysis reveals that period-doubling bifurcation occurs and an amplitude-modulated ENSO emerges. At this point, a subcycle appears within the preexisting ENSO cycle, which initiates decadal modulation of ENSO. As Tr increases further, nested oscillations are successively generated, illustrating clear decadal modulation of ENSO. The qualitative regime changes revealed in this study are supported by the observation of regime shifts in the 1970s. With increasing Tr, the mean zonal SST gradient increases, and the model adjusts toward a "La Niña-like" mean state. Further constraint with shoaling of the mean thermocline depth and increasing stratification causes ENSO to exhibit stronger amplitude modulation. Furthermore, the timing of the period-doubling bifurcation advances with these two effects. © 2011 American Meteorological Society. Source

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