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Due to the unique geographical location and sensitive response to global climate changes, the Antarctic region plays an important role in paleoclimate researches, and attracts great attentions from various scholars. One 324 cm long sediment core (ANT29-P7-09) was obtained from Prydz Bay, Antarctica, during the 29th Chinese National Antarctic Research Expedition. Based on sediment particle size, TOC, δ13C analyses and magnetism data, the authors show that the dominant magnetic minerals are ferrimagnetic pseudo single domain (PSD)-multi domain (MD) magnetite. Variations in the paleoenvironmental records allow us to define 4 zones in the core. These zones outline the climatic variations in the region since the late Early Pleistocene, including a warm period, a transitional period, and a cold period. The magnetic particle assemblage varies with glacial-interglacial cycles. Abrupt changes in particle size, TOC content, and geomagnetism occur at 102–90 cm deep in the core, indicating a sudden warming in the Antarctic region, signaling the onset of the Holocene. The authors identified 3 additional climatic signals in the middle part of the core (232–162 cm) that show unexpected cooling events during the warm period in Prydz Bay, Antarctica.

A Gram-stain-negative, aerobic, yellow-coloured, motile by gliding, rod-shaped bacterial strain, designated R17H11T, was isolated from surface sediment collected from the Ross Sea, Antarctica. Growth optimally occurred at 25–30 °C, at pH 7.0–7.5 and in the presence of 3 % NaCl (w/v). Phylogenetic trees based on 16S rRNA gene sequences indicated that strain R17H11T clustered together with Gramella flava JLT2011T and fell within the genus Gramella . Strain R17H11T shared the highest 16S rRNA gene similarities (96.1 and 96.0 %) with the type strains of Gramella forsetii and G. flava , and 92.6–95.5 % similarities with those of other known Gramella species. Strain R17H11T contained menaquinone-6 as the only isoprenoid quinone. The major fatty acids (>5 %) were summed feature 3 (17.5 %, comprising C16 : 1 ω7c and/or C16 : 1 ω6c), iso-C15 : 0 (14.0 %), summed feature 9 (11.8 %, comprising 10-methyl C16 : 0 and/or iso-C17 : 1 ω9c), iso-C17 : 0 3-OH (11.8 %), iso-C16 : 0 (7.4 %), C17 : 1 ω6c (6.9 %) and anteiso-C15 : 0 (5.1 %). The major polar lipids were phosphatidylethanolamine, four unidentified lipids, an unidentified aminolipid, an unidentified aminophospholipid and an unidentified glycolipid. The DNA G+C content of strain R17H11T was 38.6 mol%. On the basis of the phylogenetic, physiological and chemotaxonomic characteristics, strain R17H11T represents a novel species in the genus Gramella , for which the name Gramella antarctica sp. nov. is proposed. The type strain of the novel species is R17H11T (=GDMCC 1.1208T=KCTC 52925T).

The benthic bacterial community in Antarctic continental shelf ecosystems are not well-documented. We collected 13 surface sediments from the Ross Sea, a biological hotspot in high-latitude maritime Antarctica undergoing rapid climate change and possible microflora shift, and aimed to study the diversity, structure and assembly mechanism of benthic bacterial community using both culture-dependent and -independent approaches. High-throughput sequencing of 16S rRNA gene amplicons revealed 370 OTUs distributed in 21 phyla and 284 genera. The bacterial community was dominated by Bacteroidetes, Gamma- and Alphaproteobacteria, and constituted by a compact, conserved and positively-correlated group of anaerobes and other competitive aerobic chemoheterotrophs. Null-model test based on βNTI and RCBray indicated that stochastic processes, including dispersal limitation and undominated fractions, were the main forces driving community assembly. On the other hand, environmental factors, mainly temperature, organic matter and chlorophyll, were significantly correlated with bacterial richness, diversity and community structure. Moreover, metabolic and physiological features of the prokaryotic taxa were mapped to evaluate the adaptive mechanisms and functional composition of the benthic bacterial community. Our study is helpful to understand the structural and functional aspects, as well as the ecological and biogeochemical role of the benthic bacterial community in the Ross Sea.

As the latest abrupt cold event, the study on the Younger Dryas event is important to forecast the change of future climate, especially to present global warming. So that what caused the event and how the event worldly spread is crucial to anticipate anything like that. Spatial distribution and relative timing of the Younger Dryas event are central for our understanding of causes and transferring mechanism of it. From the large numbers of the published works on the late Quaternary paleoclimatic research, the evidences of the Younger Dryas event were summarized and the accurate coordinates of these sites were put on the world map with Mapinfo software From more than 200 sites which have the event records, the onset, the termination and duration trend of it are figured and analyzed. The onset time of the event is different from 11.8 cal. ka B.P. to 13.7 cal. ka B.P. The mean value is 12.72 cal. ka B.P. The contour line of 12.8 cal. ka B.P. circle more than half of the earth, from Europe to Qinghai-Tibet Plateau, southwest Pacific, east Antarctica, South Africa, South Atlantic Ocean and South America. The earliest site is 13.7 cal. ka B.P. at MD01-2386 core, West Pacific Warm Pool and at AD91-17, South Adriatic Sea, not at Arctic region. The end time of the event is 7.8-12.53 cal. ka B.P., mean is 11.52 cal. ka B.P. The contour line of 11.5 cal. ka B.P. covers almost north Hemisphere except North Africa and west Pacific, from north to south total tread of the terminative time is younger. The terminative time of the event at continents is earlier than around oceans. The duration of the Younger Dryas event is 0.25-4.46 cal. ka, the mean value is 1.20 cal. ka. The areas more than 1.2 cal. ka is most in low latitude. At the North Africa and the West Pacific Warm Pool the duration is longer than at other places. While at high latitude it is shorter. The results indicate that the origin of the Younger Dryas event is at West Pacific Warm Pool. The trigger is Qinghai-Tibet Plateau. The changing of the atmosphere general circulation is the reason of the beginning and the ending of the event. And the signs of the event are transferred by the air circulation and ocean-air exchanging. Because special factors the local responses of the Younger Dryas event are diversity in different places.

Zhujiang Submarine Canyon, a large submarine canyon, is located in the northern South China Sea, extending to 300 km southeastward from the shelf break off Zhujiang River estuary, down to deep-sea basin. Based on the full-coverage multi-beam seabed terrain data, the subtle topographic features of Zhujiang Submarine Canyon are analyzed. According to the morphology, trend, and bottom axial gradient, Zhujiang Submarine Canyon is divided into upper, middle and lower segments and deep-sea fan. On the basis of geomorphology, tectonic interpretation indicates that Zhujiang Submarine Canyon is mainly affected by the northeast-trending faulted basin and northwest-trending fault belt since Mesozoic, followed by the east-west-trending fault belt. Zhujiang Submarine Canyon maybe formed by the continuing thermal subsidence and fault depression of northern South China Sea margin caused by South China Sea spreading based on the collision between India-Australian plate and Eurasian plate. The submarine canyon becomes more narrow and deeper at the entrance because of the submarine volcanoes formed by the volcanic eruptions in Neogene. Zhujiang Submarine Canyon is continual eroded and filled by the cyclical sea level changing and massive sediment carried by Zhujiang River. The thick sediments, slump layer and developed fracture are conducive to migration, aggregation and accumulation of hydrocarbon. And the surface hydrocarbon spill formed the seabed pockmark structure on the north slope of the submarine canyon.

An efficient channel estimation algorithm using a variable step-size adaptive filter is proposed for wideband code division multiple access (WCDMA) communication systems. The new algorithm is able to achieve a fast convergence and a low steady state error compared with a conventional constant step-size adaptive filtering method. The proposed algorithm is analyzed and simulated for multipath Rayleigh fading channels, showing the true channel response and the estimation results. The BER performance of the system is also simulated and compared with the Bhattacharyya bound.

In this paper, a two-step channel estimation scheme is presented for downlink wideband code division multiple access (W-CDMA) communication systems. The proposed method employs the time multiplexed pilot symbols for an initial coarse estimation followed by a data-aided fine estimation in order to achieve a fast and accurate estimation of the complex channel gain. Our simulation shows that the proposed method works very well for both slow and fast fading channels. The computational complexity required by the proposed estimation is significantly reduced compared to some of the existing estimation techniques.