Description: Publication date: Available online 26 December 2017 Source: Polar Science Author(s): Mitsuaki Kitamura, Yoshizumi Nakagawa, Yasuto Nishino, Susumu Segawa, Akihiro Shiomoto Replacement of the warm water of the Soya Warm Current (SWC) and the cold water of the East Sakhalin Current (ESC) occurs seasonally along the coast of the southwestern Okhotsk Sea, and sea ice covers the surface during winter. Pseudocalanus newmani is one of the dominant copepods in coastal waters of the northern hemisphere. To better understand the population dynamics of the copepod P. newmani in coastal areas of the southwestern Okhotsk Sea, this study compared the seasonal variation in P. newmani abundance in Lagoon Notoro-ko and a coastal area of the Okhotsk Sea with regard to developmental stage. We sampled P. newmani in the lagoon, including during the ice cover season, and the coastal waters. Pseudocalanus newmani was abundant at both sites in spring. During summer–fall, adults disappeared from the populations at both sites, whereas the early developmental stages were abundant and dominated the population. Total length of adult females decreased toward summer at both sites. Pseudocalanus newmani abundance in the lagoon increased in early winter, and larger females were found in the populations at both sites. These phenomena at both sites corresponded with seasonal variation in water temperature caused by seasonal water-mass replacement and sea ice.

Description: Publication date: Available online 19 December 2017 Source: Polar Science Author(s): Hyungbeen Lee, Hyoung Sul La, Donhyug Kang, SangHoon Lee Mid-trophic level at high-latitude coastal water in the Southern Ocean reside unique geographical condition with sea ice, coastal polynya, and ice shelf. To investigate the regional differences in their vertical distribution during summer, we examined acoustic backscatter data from scientific echo sounder, collected in the three representative regions in the Amundsen Sea: pack ice zone, coastal polynya zone, and ice shelf zone. The weighted mean depths (WMDs) representing zooplankton were calculated with the high resolution acoustic backscatter (1-m depth) to identify the vertical variability of the sound-scattering layer (SSL). WMDs were mainly distributed between 50 and 130 m exhibiting clear regional differences. The WMDs were detected in the shallow depth ranged between 48 and 84 m within the pack ice and coastal polynya, whereas they were observed at deeper depths around near ice shelf ranged between 117 and 126 m. WMDs varied with changing the stratification of water column structure representing strong linear relationship with the mixed layer depth ( r  = 0.69). This finding implies that understanding the essential forcing of zooplankton behavior will improve our ability to assess the coastal ecosystem in the Southern Ocean facing dramatic change.

Description: Publication date: Available online 11 December 2017 Source: Polar Science Author(s): Masakuni Yamanobe, Tomoki Nakamura, Daisuke Nakashima To understand oxygen isotope ratios and redox conditions of the chondrule formation environments of the outer rigions of the asteroid belt, we analyzed major element concentrations and oxygen isotope ratios of olivine grains in chondrules, isolated forsterite, and isolated olivine from the WIS 91600 and MET 00432 carbonaceous chondrites, which are thought to have originated from D-type asteroids located in the outer asteroid belt. The oxygen isotope ratios of individual chondrules and isolated grains show a wide variation in δ 18 O from –9.9‰ to +9.1‰ along the carbonaceous chondrite anhydrous mineral (CCAM) and primitive chondrule mineral (PCM) lines. The Δ 17 O (= δ 17 O – 0.52 × δ 18 O) values of the measured objects increase with decreasing Mg#; i.e., FeO-poor objects (Mg# > 90; type I chondrules and isolated forsterites) mainly have Δ 17 O values of ca. –6‰, and FeO-rich objects (Mg# 〈 90; type II chondrules and isolated olivines) have Δ 17 O values ranging from –3‰ to +2‰. Similar trends are observed for ferromagnesian silicate particles from comet Wild2 and CR chondrite chondrules, particularly in terms of FeO-rich objects with Δ 17 O values ranging from –3‰ to +2‰. It is suggested that FeO-rich objects formed in the outer regions of the asteroid belt and were transported to the outer solar nebular regions where comet Wild2 formed.

Description: Publication date: Available online 5 December 2017 Source: Polar Science Author(s): M. Kimura, N. Imae, A. Yamaguchi, H. Haramura, H. Kojima Bulk chemical compositions of meteorites were traditionally analyzed by wet chemical analysis, and NIPR has data for 1162 meteorites as of September 2017. We discuss the classification of meteorites on the basis of these data. Chondrite data are distributed in an anomalously wide range of compositions on the Urey-Craig diagram. One of the reasons for such wide distribution is terrestrial weathering producing Fe 2 O 3 –bearing phases from Fe-Ni metal and sulfides. Another important factor affecting the bulk compositional data is brecciation. Our observations indicate that many brecciated chondrites contain anomalously abundant opaque minerals, or are depleted in them, resulting in unusual compositions. In case of enstatite and some carbonaceous chondrites, the bulk compositions are distributed in wider ranges than reported before. The bulk compositions of HED meteorites are consistent with their mineralogy and classification. Our study suggests that wet chemical data are still significant for the meteorite classification. However, petrographic observation is indispensable for evaluating the bulk chemistry and classification of meteorites.

Description: Publication date: Available online 24 October 2017 Source: Polar Science Author(s): Yogabaanu Ulaganathan, Jean-Frederic Faizal Weber, Peter Convey, Mohammed Rizman-Idid, Siti Aisyah Alias The Arctic and Antarctic share environmental extremes. To survive in such environments, microbes such as soil fungi need to compete with or protect themselves effectively from other soil microbiota and to obtain the often scarce nutrients available, and many use secondary metabolites to facilitate this. We therefore (i) screened for antimicrobial properties of cold-environment Arctic and Antarctic soil fungi, and (ii) identified changes in the secreted secondary metabolite profiles of a subset of these strains in response to temperature variation. A total of 40 polar soil fungal strains from King George Island, maritime Antarctic and Hornsund, Svalbard, High Arctic, were obtained from the Malaysian National Antarctic Research Centre culture collections. The plug assay technique was used to screen for antimicrobial potential against Gram-positive and Gram-negative human pathogenic bacteria ( Bacillus subtilis , B. cereus , Pseudomonas aeruginosa , Enterococcus faecalis and Escherichia coli ). About 45% of the tested fungal strains showed antimicrobial activity against at least one tested microorganism. Three fungal isolates showed good bioactivity and were subjected to secondary metabolite profiling at different temperatures (4, 10, 15 and 28 °C). We observed a range of responses in fungal metabolite production when incubated at varying temperatures, confirming an influence of environmental conditions such as temperature on the production of secondary metabolites.

Description: Publication date: Available online 18 October 2017 Source: Polar Science Author(s): N. González-Ballesteros, J.B. González-Rodríguez, M.C. Rodríguez-Argüelles, M. Lastra In this study, two Antarctic macroalgae (Rhodophyta Palmaria decipiens and Phaeophyta Desmarestia menziessi ) were selected in order to report their use for the biosynthesis of nanomaterials. Two aqueous extracts of the macroalgae were prepared and their reducing activity, total phenolic content and DPPH scavenging activity were determined, showing that brown seaweed has higher antioxidant activity than red seaweed. Aqueous extracts were used as an eco-friendly, one-pot synthetic route to obtain gold and silver nanoparticles acting both as reducing and stabilizing agents. The nanoparticles obtained were characterized by UV–Vis spectroscopy and Transmission electron microscopy (TEM), demonstrating the formation of gold and silver nanoparticles with mean diameters of 36.8 ± 5.3 and 11.5 ± 3.3 nm for Au@PD and Au@DM and 7.0 ± 1.2 nm and 17.8 ± 2.6 nm in the case of Ag@PD and Ag@DM. Lastly, functional groups of the biomolecules present in the extracts were characterized by Fourier transform infrared spectra (FTIR) prior to, and after, the synthesis of the nanoparticles, in order to obtain information about the biomolecules involved in the reducing and stabilization process.

Description: Publication date: Available online 14 October 2017 Source: Polar Science Author(s): A. Novoselov, I. Potravny, I. Novoselova, V. Gassiy In the Russian Arctic, there is currently an active process of preparation and implementation of investment projects aiming to extract natural resources, with the aim of sustainable socioeconomic development of the region. These projects are associated with the development of key zones in the Arctic and involve the exploration for and production of minerals (diamonds, gold, rare-earth metals, oil, and gas) and the development of energy and infrastructure (e.g., the Northern Sea Route). Such projects, which are often carried out in territories of traditional nature management belonging to the indigenous peoples of the North, must consider their environmental and social responsibility and the preservation of the ethnic identity and culture of indigenous peoples. The extraction of mineral deposits in the Arctic and the Far North places new demands on subsoil users, related to the preservation and development of the socio-cultural environment of the indigenous peoples of the North and to the ecological rehabilitation of the area. This article presents economic and mathematical models for selecting the optimal development project options based on the pairwise comparison of investment projects and the evaluation of indigenous peoples' preferences. We investigated the investment projects' impact on traditional territories in the Arctic, including the Republic of Sakha (Yakutia), in terms of socioeconomic and ethnological development, and environmental change. The suggested system of models can be used to assess the priority of projects supporting and developing the region in the mining corporation's area of responsibility. The proposed models are based on fuzzy set theory, which provides an effective assessment of the population's preferences for projects. Data are processed using the hierarchy analysis method and multivariate optimization calculations to determine the project sets at different funding levels. The creation of information-linked processing models is innovative. Indigenous people's expert assessments of the priority of projects are processed using the hierarchy analysis method to determine the coefficients of the optimization model that enables the calculation of the choice between the analyzed projects, given the allocated financial resources. This approach can be used to address issues of support for indigenous people in areas where mining and other economic development activities are taking place, especially in the Arctic region. The proposed decision-making mechanism, which includes public hearings, sociological surveys, ethnological expertise, and compensation payments to indigenous minorities of the North, facilitates the justification of optimal strategies for maintaining and developing the region, taking into account economic, ecological, social, and ethnological factors.

Description: Publication date: Available online 13 October 2017 Source: Polar Science Author(s): Kaoru Shiramizu, Koichiro Doi, Yuichi Aoyama A digital elevation model (DEM) is used to estimate ice-flow velocities for an ice sheet and glaciers via Differential Interferometric Synthetic Aperture Radar (DInSAR) processing. The accuracy of DInSAR-derived displacement estimates depends upon the accuracy of the DEM. Therefore, we used stereo optical images, obtained with a panchromatic remote-sensing instrument for stereo mapping (PRISM) sensor mounted onboard the Advanced Land Observing Satellite (ALOS), to produce a new DEM (“PRISM-DEM”) of part of the coastal region of Lützow–Holm Bay in Dronning Maud Land, East Antarctica. We verified the accuracy of the PRISM-DEM by comparing ellipsoidal heights with those of existing DEMs and values obtained by satellite laser altimetry (ICESat/GLAS) and Global Navigation Satellite System surveying. The accuracy of the PRISM-DEM is estimated to be 2.80 m over ice sheet, 4.86 m over individual glaciers, and 6.63 m over rock outcrops. By comparison, the estimated accuracy of the ASTER-GDEM, widely used in polar regions, is 33.45 m over ice sheet, 14.61 m over glaciers, and 19.95 m over rock outcrops. For displacement measurements made along the radar line-of-sight by DInSAR, in conjunction with ALOS/PALSAR data, the accuracy of the PRISM-DEM and ASTER-GDEM correspond to estimation errors of 〈6.3 mm and 〈31.8 mm, respectively.

Description: Publication date: Available online 13 October 2017 Source: Polar Science Author(s): Takahiko Murayama, Masaki Kanao, Masa-Yuki Yamamoto, Yoshiaki Ishihara, Takeshi Matsushima, Yoshihiro Kakinami, Kazumi Okada, Hiroki Miyamachi, Manami Nakamoto, Yukari Takeuchi, Shigeru Toda Characteristic features of infrasound waves observed in the Antarctic reflect the physical interaction between the surface environment along the continental margin and the surrounding Southern Ocean. The temporal–spatial variability of the source locations for infrasound excitation during the eight-month period between January and August 2015 was investigated using recordings made by two infrasound arrays deployed along a section of the coast of Lützow–Holm Bay (LHB), Antarctica. The infrasound arrays clearly detected temporal variations in frequency content and propagation direction during this period. A number of infrasound sources were identified, many located north of the arrays. Many of the events had a predominant frequency content of a few Hz, higher than microbaroms from the ocean. A comparison of the results with MODIS satellite images indicated that these infrasound sources were ice-quakes associated with the calving of glaciers, the breaking off of sea ice, and collisions between this sea ice and icebergs around the LHB. Continuous measurements of infrasound in the Antarctic may serve as a proxy for monitoring the regional surface environment in terms of climate change at high southern latitudes.

Description: Publication date: Available online 27 September 2017 Source: Polar Science Author(s): Rusheng Wang, Liu An, Pinlu Cao, Baoyi Chen, Mikhail Sysoev, Dayou Fan, Pavel G. Talalay This article describes the investigation of the feasibility of rapid drilling in ice sheets and glaciers to depths of up to 600 m, with cuttings and cores continually transported by air reverse circulation. The method employs dual wall drill rods. The inner tubes provide a continuous pathway for the chips and cores from the drill bit face to the surface. To modify air reverse circulation drilling technology according to the conditions of a specific glacier, original cutter drill bits and air processing devices (air-cooled aftercoolers, air receivers, coalescing filters, desiccant dryers) should be used. The airflow velocity for conveying a 60-mm diameter and 200-mm long ice core should not be lower than 22.5 m/s, and the minimal airflow rate for continual chip and cores transport is 6.8 m 3 /min at 2.3–2.6 MPa. Drilling of a 600-m deep hole can be accomplished within 1.5 days in the case of twenty-four hour drilling operations. However, to avoid sticking while drilling through ice, the drilling depth should to be limited to 540 m at a temperature of -20 °C and to 418 m at a temperature of -10 °C.