Description: Publication date: Available online 19 May 2018 Source: Polar Science Author(s): Vimlesh Pant, Jaswant Moher, Vivek Seelanki The Community Earth System Model with the biogeochemistry module (CESM1-BGM) was used with RCP8.5 scenario to examine the spatial and temporal variability in the oceanic CO 2 flux and biogeochemical parameters for the years 1850–2100. The 10-year periods of 1850–1860, 2010–2020, and 2090–2100 were used to represent the oceanic conditions in the past (historical), present, and future climate, respectively. The model simulations showed interesting differences between CO 2 flux and biogeochemical parameters in the northern (NH) and southern (SH) high latitude oceanic regions. The sea surface temperature increases monotonically during 1960–2100 in both the hemispheres. The enhanced CO 2 concentrations in the air lead to an increase in CO 2 flux into the SH high-latitudes resulting into increasing oceanic acidification. However, over the NH high latitudes, the increase in CO 2 flux ceased by the year 2050 and decreased during 2080–2100. This decrease in the warming of Arctic waters could be associated with the freshwater addition due to ice-melt that reduces the mixed layer depth in northern high latitudes and decreases CO 2 uptake in future climate. The biological productivity (Chl concentrations) in the NH high latitudes found to decrease rapidly (2.5 mg m −3 lower than present) during 2000–2100. The time-series analysis of biogeochemical parameters at three regions in each hemisphere reveals marked differences over different oceanic regions within the same hemisphere in addition to the inter-hemispheric differences. The changes in large-scale overturning circulation and enhanced stratification leads to a reduction in nutrient supply to surface waters from deeper layers and decreases Chl concentration in the NH region. The mixing caused by Antarctic circumpolar current plays crucial role in maintaining Chl concentrations in the southern ocean. The multi-decadal spatiotemporal variability in physical and biogeochemical parameters are discussed in terms of their inter-dependence, oceanic processes, air-sea exchange in the warming climate.

Description: Publication date: Available online 3 May 2018 Source: Polar Science Author(s): Dhruv Sen Singh, Chetan Anand Dubey, Dhirendra Kumar, Pankaj kumar, Rasik Ravindra The Ny-Alesund region is characterised by diversified surface processes which carve the landscape and so exhibits variable and complex landforms. Extensive work has been carried out on climate change using various proxies however no much attention has been paid in understanding the climate events using geomorphological and sedimentological parameters. In the present paper sediment characteristics, AMS 14 C dates and geomorphic features have been used for the reconstruction of palaeoclimate. On the basis of distribution of landforms, and sediments, this region has been classified into five morphological zones such as glacial (moraines GL), proglacial (lacustrine deposits LD), outwash plain (sandur deposits OWP), fluvial deposits (FD) and coastal cliff (CC). The geomorphic analysis and sedimentary parameters revealed that GL consists of unconsolidated, unstratified, massive, devoid of any sedimentary structures, coarse grained, matrix supported boulders, whereas OWP, LD, FD and CC are semi-consolidated, stratified, fine grained, layers of sand, silt, and clay with gravels and faint sedimentary structures. The sediments of CC and LD are very poorly sorted, very positively skewed, very leptokurtic, medium to fine sand, silt and clay. The sediment characteristics coded in the geomorphic features of various morphological zones explains that this region was carved and dominated by glaciers under cold climate at ice stages during 47.5, 38, 23, 18, 8.8, 6.l, 1 ka BP and paraglacial processes under warm climate at interglacial stages during 44, 27, 12, 10.5 ka BP. The poorly sorted sediments for all the morphological zones explain the fluctuating energy of the depositional environment and so the prevailing climate was not consistent and persistent for long period of time.

Description: Publication date: Available online 2 May 2018 Source: Polar Science Author(s): Pawan Govil, Abhijit Mazumder, Raghu Ram, Dhruv Sen Singh, Syed Azharuddin The present study deals with the role of sedimentary processes in the lake of Schirmacher Oasis (SO), East Antarctica and their periodicities to understand the forcing mechanism responsible for the regional climate variations. We analyzed various sedimentary parameters viz. sand, silt, clay, roundness andbiogenic silica (BSI) from lake L-51. The proxy record reports the occurrence of increased freshwater runoff around 14.7–12.2 ka,.in the lake followed by Holocene climate optimum around 11.2–10 ka and 9.4–8.4 ka. The SO records the ice sheet retreat during mentioned periods. . The spectral analysis of the sedimentological parameters reveals the significant periodicities (>95% significance) centering at ∼1067, ∼907, and ∼824 years. The long-term trends in the data suggest the possible fluctuation of Antarctic ice-sheet superimposed on global climatic fluctuations due to solar activity.

Description: Publication date: Available online 9 May 2018 Source: Polar Science Author(s): Jaroslav Klokočník, Jan Kostelecký, Václav Cílek, Aleš Bezděk, Ivan Pešek By using SatGravRET2014 gravito-topography model, based also on satellite GRACE and GOCE data, we computed and plotted the gravity disturbances, the Marussi tensor of the second derivatives of the disturbing potential, the gravity invariants and their specific ratio, the strike angle and the virtual deformations for the Lake Vostok (LV) area in Antarctica. This set of gravity “aspects” provides more detailed and clearer information than the traditional gravity anomalies. Maps with the bedrock topography from Bedmap 2 are added. Some of our estimates and results confirm independent findings of other specialists, some results presented here are new. LV is divided not only into its N and S parts by a ridge, but also to E and W parts. A tension across LV has a prevailing direction E-W. We identified at least three candidates for subglacial lakes south of the lakes 90 E and Sovetskaya. In the gravity aspects this area looks like a basin, where the mentioned lakes might be just a remnant of a large bowl; the orientation of this basin is the same as that of LV; the size comparable to LV. A subglacial connection between all the mentioned lakes is possible and documented via the gravity aspects, namely by the virtual deformations.

Description: Publication date: Available online 23 April 2018 Source: Polar Science Author(s): Vikash Chandra Tripathi, Sabbu Satish, Soyar Horam, Sneha Raj, Agney lal, Jesu Arockiaraj, Mukesh Pasupuleti, Dinesh Kumar Dikshit Natural products have a huge value in pharmaceuticals industry as molecules or templates for discovery or further development of new drugs. It is predicted that, if the marine resources are explored fully, then we will have enough chemically diverse molecules to sustain us for the coming next century. For the discovery of new classes of natural products, polar organisms are emerging as a source of unknown magnitude because recent genetic based studies showed that the diversity of the polar region is much more than previously predicted. In order to survive in the cold, extreme and inhospitable environment conditions, polar organisms produce an array of unique metabolites which confer an advantage and offers protection from predation. Out of all the natural products reported from polar organisms, 38% of them showed bioactivity of pharmaceutical relevance. This high success percentage clearly illustrates the tremendous potential of the polar organisms as a source of new therapeutic agents for infectious and lifestyle associated diseases. We in this review describe the natural products discovered, isolated and characterized from the organisms (both prokaryotes and eukaryotes) found in the polar (Arctic and Antarctic) regions. Further, we discussed the problems encountered and solutions employed by the various researcher during natural product isolation from marine sources.

Description: Publication date: Available online 10 May 2018 Source: Polar Science Author(s): Pavel Talalay, Bowen Liu, Yang Yang, Xiaopeng Fan, Jialin Hong, Da Gong, Mikhail Sysoev, Xiao Li, Yazhou Li Electric thermal drills are more advantageous than electromechanical drills in temperate, near-temperate, and polythermal glaciers because they can avoid problems arising from refreezing of wet chips, which causes drills to become stuck in the borehole. When the refreezing rate of meltwater in borehole is expected to be too high and there is no considerable englacial water flow, thermal drills with meltwater removal system are optional for open-hole shallow (200–300 m) ice coring. To reach a sufficiently high rate of penetration of approximately 6–7 m h −1 , the power density of thermal head should be maintained in the range of 100–110 W cm −2 , which can be provided by tubular elements cast integrally with an aluminum or copper annulus. To remove meltwater via air reverse circulation, thermal drills can be equipped with a small blower. The safest and most even mode of water removal is lifting in the form of water film on the wall of air sucking tubes. The maximum water removal rate using a single water-lifting pipe via air reverse circulation created by a blower with a sucking power of 110 airwatts was ∼0.35 L min −1 . Assuming a penetration rate of 6–7 m h −1 and the outer and inner diameters of 135 and 110 mm, respectively, of the drill head, the meltwater should be removed at a rate not less than 0.8–1.0 L min −1 . In this case, at least three water-lifting pipes should be used in the drill.

Description: Publication date: Available online 22 April 2018 Source: Polar Science Author(s): Amita Prabhu, G. Pandithurai The robustness of southern polar linkages with the Indian Summer Monsoon Rainfall (ISMR) is affirmed by employing the Empirical Orthogonal Function (EOF) analysis on Outgoing Longwave Radiation (OLR) over the Indian region. It is observed that the OLR's primary mode of variability (EOF1), which covers almost the entire country and holds a strong positive relationship with ISMR, is significantly associated with Southern Annular Mode (SAM). The International Satellite Cloud Climatology Project (ISCCP) generated spatial distribution of clouds during the recent three decades prominently displays formation and clustering of clouds over the central Pacific as a manifestation of the ocean-atmosphere coupled interactions associated with negative mode of SAM. Further, the northwest ward progression of the cloud-free patterns from equatorial western Pacific to the Indian region is distinctly evident in the ISCCP classified High-level clouds as compared to Middle and Low clouds during the summer monsoon season, thereby inhibiting its monsoon activity. As such, this study demonstrates an association between the southern hemispheric high latitude mode and cloud dynamics over the Indo-Pacific basin having a potential implication on the performance of Indian monsoon.

Description: Publication date: Available online 9 May 2018 Source: Polar Science Author(s): A.K. Srivastava, P.S. Ingle, N. Khare The Schirmacher Oasis, East Antarctica is clearly distinguishable into three geomorphologic units i.e., i) polar ice sheet, ii) main rocky land including lakes, and iii) coastal shelf. These units have different processes for the release and accumulation of sediments because of various physical and chemical factors operating either individually or, in combination. The cumulative effect of these factors is the accumulation of sediments which are normally represented by loose admixture of clasts, sand, silt and clay. Sedimentological studies of these sediments provide a good idea about various endogenic and exogenic processes going on in the area and their affect on nature and pattern of sedimentation as well as paleoclimatic conditions, hydrodynamic, depositional setup, clay mineralization. In the present work, compilation and reinterpretation of the work carried out in the past on the aspects of granulometry, heavy minerals and clay minerals have been carried out together for various geomorphological units and entire area together to interpret various factors responsible for sediment accumulation. It has been observed that wind, melt water and ice are the main controlling factors for the present scenario of nature and composition of glacial sediments of the Oasis. Comments have also been made on the paleoclimatic conditions.

Description: Publication date: Available online 27 April 2018 Source: Polar Science Author(s): Neelu Singh, S. Rajan, Shabnam Choudhary, Magesh Peter, C. Krishnaiah Surface sediment samples from Kongsfjorden were analysed for Polycyclic Aromatic Hydrocarbons (PAHs) to understand their source and process responsible for their deposition in the sediment. PAHs were detected between 72.91 and 318.73 ng g −1 in 2012 and 72.54–311.97 ng g −1 in 2013 showing a decreasing trend from the mouth of the fjord towards the glacier head. During these years, 2, 6-diisopropylnapthalene (DIPN) showed concentration ranging from 1.21 ng g −1 to 5.87 ng g −1 and 1.31 ng g −1 to 4.79 ng g −1 with an increasing trend from the mouth of the fjord towards the glacial outlet. This systematic increase of DIPN towards the glacier is observed during both the years of sampling which supports the possibility of DIPN from human activities at Ny-Ålesund and its surroundings. DIPN in the environment has not been thoroughly investigated and its present-day concentrations may not be alarming, however, considering the increasing anthropogenic activities at Ny-Ålesund, it might be prudent to exercise caution to ensure that the levels do not increase over time.

Description: Publication date: Available online 21 April 2018 Source: Polar Science Author(s): Pranab Deb, Mihir K. Dash, Prem Chand Pandey Barrier layer in the Enderby Basin (EB) and the Australian Antarctic Basin (AAB) during late summer (December & January) and early autumn (February & March) are studied using temperature-salinity profiles collected between 1975 and 2012. A distinct difference in mixed layer depth is observed over the eastern (i.e. the EB) compared to western (i.e. the AAB) side of the Kerguelen Plateau (KP), with shallower mixed layer depths on the eastern side. Mixed layers show an increase from less than 50 m–∼150 m from south to north in the EB. During autumn, the wind strengthens and the upwelling over the eastern side of the KP (i.e. in the AAB) weakens, resulting in deeper mixed layers (∼80 m–100 m) compared to summer. During summer, deep barrier layer (BL) values (∼50 m or more) with porosity less than 0.3 was seen over the Chun Spur region. The fresher melt water from the EB brought by the Fawn trough current (FTC) across the KP may be responsible for the occurrence of BL over the region. During autumn, BL is spread over a much larger area around the Chun Spur, which could be attributed to the increase in the strength of FTC due to the intensification of wind over the region. A thorough study of BL condition over this region is required to understand the processes behind the discrepancies in sea ice conditions.