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Search Results: 1 - 10 of 435 matches for " Arctic "
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Review of Black Carbon in the Arctic—Origin, Measurement Methods, and Observations  [PDF]
Nicole M?lders, Stanley G. Edwin
Open Journal of Air Pollution (OJAP) , 2018, DOI: 10.4236/ojap.2018.72010
Abstract: Current knowledge about black carbon (BC) emission estimates, state-of-the-art measurement methods, near-surface BC concentrations ([BC]), and mixing ratios in snow is consolidated for the Arctic. Since no direct method exists to measure [BC], results from modern indirect methods differ among devices. Pan-Arctic wide [BC] and changes are hard to access; monitoring often ends once national ambient air quality standards are met. Few remote sites have long records. Past measurements showed distinct differences among the various Arctic climate regions. Past and own observations in communities permit qualitative discussion of the diurnal course, response to weather, season, or different emission situations like weekdays and weekends at a given site and/or among sites. Comparison of data from collocated aethalometer indicated more similar accuracy than found in mid- and low-latitudes despite of much lower ambient temperatures and [BC]. Snow samples give an incomplete glimpse at the removal and input into ecosystems.
Effects of feeding a pigmented or non-pigmented diet to Arctic charr, Salvelinus alpinus, on flesh color and sexual maturity  [PDF]
Mary A. McNiven, Gavin F. Richardson, Claude S. Pelletier
Open Journal of Animal Sciences (OJAS) , 2012, DOI: 10.4236/ojas.2012.24032
Abstract: The objective of this study was to evaluate the effects of feeding pigmented feed (50 ppm astaxanthin) to diploid or triploid Arctic charr, Salvelinus alpinus, on growth rate, color of fillets, and the variability of color within fillets. Arctic charr with an average weight of 419.9 g ± 83.3 g, including both diploid (n = 72) and triploid (n = 72) fish, were allotted to each treatment: 0, 3 or 6 months of pigmented feed before slaughter. Color assessment was made using a portable reflected light colorimeter in the CIE 1976 L* a* b* color system mode. Feeding a pigmented diet to Arctic charr delayed sexual maturity in male Arctic charr and to a certain extent in females, but also slightly reduced the rate of growth. With increasing time on the pigmented diet, color parameters of the flesh increased as well as the variability in color. Triploid fish had more intense color assessments for each dietary treatment than the diploid fish.
The Diversity of Chrysophycean Algae in an Arctic Zone of River and Sea Water Mixing, Russia  [PDF]
Alena D. Firsova, Anna Yu Bessudova, Larisa M. Sorokovikova, Irina V. Tomberg, Yelena V. Likhoshway
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.615246
Abstract: According to the results of studies in the region of lower Yenisei River to the Kara Sea shelf in September 2009, the flora of chrysophyte algae in the zone of river and sea water mixing comprises 43 species of the classes Chrysophyceae and Synurophyceae. Most of them are cosmopolitan and widespread, but four rare species have also been recorded. The most frequent species are Synura petersenii f. petersenii, S. petersenii f. kufferathii, Spiniferomonas takahashii, Mallomonas acaroides, and M. crassisquama. The composition of chrysophyte flora in the study region is similar to that in some lakes of the Taimyr Peninsula. It has been found that the diversity of chrysophytes in the zone of river and sea water mixing depends on water salinity, with a group of species occurring at increased salinity levels. It includes Chrysosphaerella coronacircumspina (5.2‰), Kephyrion spirale (5.2‰) and Mallomonas crassisquama (8‰). These data contribute to knowledge of how the distribution of chrysophytes responds to changes in ecological conditions such as water salinity, turbidity, pH, and concentrations of oxygen and mineral phosphorus.
Department of Arctic Biology, Troms - new facilities
Sven Skjenneberg (ed.)
Rangifer , 1993,
Abstract:
Arctic Ocean Scientific Drilling: The Next Frontier
Bernard Coakley,Ruediger Stein
Scientific Drilling , 2010, DOI: 10.2204/iodp.sd.9.09.2010
Abstract: The modern Arctic Ocean appears to be changing faster than any other region on Earth. To understand the potential extent of high latitude climate change, it is necessary to sample the history stored in the sediments filling the basins and covering the ridges of the Arctic Ocean. These sediments have been imaged with seismic reflection data, but except for the superficial record, which has been piston cored, they have been sampled only on the Lomonosov Ridge in 2004 during the Arctic Coring Expedition (ACEX-IODP Leg 302; Backman et al., 2006) and in 1993 in the ice-free waters in the Fram Strait/Yermak Plateau area (ODP Leg 151; Thiede et al., 1996).Although major progress in Arctic Ocean research has been made during the last few decades, the short- and long-term paleoceanographic and paleoclimatic history as well as its plate-tectonic evolution are poorly known compared to the other oceans. Despite the importance of the Arctic in the climate system, the database we have from this area is still very weak. Large segments of geologic time have not been sampled in sedimentary sections. The question of regional variations cannot be addressed.
Atmospheric Deposition and Critical Loads for Nitrogen and Metals in Arctic Alaska: Review and Current Status  [PDF]
Greg Linder, William Brumbaugh, Peter Neitlich, Edward Little
Open Journal of Air Pollution (OJAP) , 2013, DOI: 10.4236/ojap.2013.24010
Abstract:

To protect important resources under their bureau’s purview, the United States National Park Service’s (NPS) Arctic Network (ARCN) has developed a series of “vital signs” that are to be periodically monitored. One of these vital signs focuses on wet and dry deposition of atmospheric chemicals and further, the establishment of critical load (CL) values (thresholds for ecological effects based on cumulative depositional loadings) for nitrogen (N), sulfur, and metals. As part of the ARCN terrestrial monitoring programs, samples of the feather moss Hylocomium splendens are being collected and analyzed as a cost-effective means to monitor atmospheric pollutant deposition in this region. Ultimately, moss data combined with refined CL values might be used to help guide future regulation of atmospheric contaminant sources potentially impacting Arctic Alaska. But first, additional long-term studies are needed to determine patterns of contaminant deposition as measured by moss biomonitors and to quantify ecosystem responses at particular loadings/ ranges of contaminants within Arctic Alaska. Herein we briefly summarize 1) current regulatory guidance related to CL values 2) derivation of CL models for N and metals, 3) use of mosses as biomonitors of atmospheric deposition and loadings, 4) preliminary analysis of vulnerabilities and risks associated with CL estimates for N, 5) preliminary analysis of existing data for characterization of CL values for N for interior Alaska and 6) implications for managers and future research needs.

 

Regional Analysis of NASA Satellite Greenness Trends for Ecosystems of Arctic Alaska  [PDF]
Christopher Potter
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.59085
Abstract:

Trends in the growing season MODerate resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time-series were analyzed for the period from 2000 to 2010 to understand landscape-level patterns of vegetation change in ecosystems of arctic Alaska. We compared datasets for vegetation cover types, wetland cover classes, wildfire boundaries since the 1940s, permafrost type, and elevation to identify the most likely combination of factors driving regional changes in habitat quality and ecosystem productivity. Approximately 57% of all arctic ecosystem areas in Alaska were detected with significant (p < 0.05) positive or negative MODIS growing season EVI trends from 2000 to 2010. Nearly all (99%) of these ecosystem areas (covering 178,050 km2) were detected with significant positive growing season EVI trends. The vast majority of the arctic Alaska region detected with significant positive growing season EVI trends was classified as upland tundra cover, although non-forested wetlands (marshes, bogs, fens, and floodplains) were co-located on 8% of that area. Herbaceous wetlands were co-located on 55% of the total area detected with significant negative growing season EVI trends, mostly on the arctic coastal plain and foothills. This evidence supports the hypothesis that temperature (warming) has markedly enhanced the rates of upland tundra vegetation growth across most of arctic Alaska over recent years.

The Chinese “(big) polar game“
Filijovi? Marko
Medjunarodni Problemi , 2011, DOI: 10.2298/medjp1103392f
Abstract: Climate changes have caused ice melting in the Arctic, thus creating new conditions in the region. Apart from making access to hydrocarbon deposits the Arctic region is rich in, new ways of transportation have appeared. In summer, the region is almost completely passable, thus making the routes between America and Asia much shorter. This has drawn attention not only of Arctic states, but also of some others, these especially including big exporters of consumer goods, as China and Japan are. The paper analyses the position of China with regard to other countries that are interested in exploitation of the Arctic region with focus on transport, in particular. Special attention is directed towards the strategic orientations of the Chinese management, this including the analysis of its approach, but also the positions of the international and especially the Chinese academic circles concerning the political and economic implications of joining of China to “the Arctic race“.
Holes in Progressively Thinning Arctic Sea Ice Lead to New Ice Algae Habitat
Sang Heon Lee |,C. Peter McRoy,Hyoung Min Joo,Rolf Gradinger
Oceanography , 2011,
Abstract: The retreat and thinning of Arctic sea ice associated with climate warming is resulting in ever-changing ecological processes and patterns. One example is our discovery of myriad new "marine aquaria" formed by melt holes in the perennial sea ice. In previous years, these features were closed, freshwater melt ponds on the surface of sea ice. Decreased ice thickness now allows these ponds to melt through to the underlying ocean, thus creating a new marine habitat and concentrating a food source for the ecosystem through accumulation of algae attached to refreezing ice in late summer. This article describes the formation of these late-season algal masses and comments on their overall contribution to Arctic ecosystems and the consequences of a continued decline in sea ice.
Analysis of Observed and Modelled Near-Surface Wind Extremes over the Sub-Arctic Northeast Pacific  [PDF]
Alexander Kislov, Vladimir Platonov
Atmospheric and Climate Sciences (ACS) , 2019, DOI: 10.4236/acs.2019.91010
Abstract: Wind speed extremes in the sub-Arctic realm of the North-East Pacific region were investigated through extreme value analysis of wind speed obtained from wind simulations of the COSMO-CLM (Consortium for Small-scale Modelling, climate version) mesoscale model, as well as using observed data. The analysis showed that the set of wind speed extremes obtained from observations is a mixture of two different subsets each neatly described by the Weibull distribution. Using special metaphoric terminology, they are labelled as “Black Swans” and “Dragons”. The “Dragons” are responsible for strongest extremes. It has been shown that both reanalysis and GCM (general circulation model) data have no “Dragons”. This means that such models underestimate wind speed maxima, and the important circulation process generating the anomalies is not simulated. The COSMO-CLM data have both “Black Swans” and “Dragons”. This evidence provides a clue that an atmospheric model with a detailed spatial resolution (we used in this work the data from domain with 13.2 km spatial resolution) does reproduce the special mechanism responsible for the generation of the largest wind speed extremes. However, a more thorough analysis shows that the differences in the parameters of the cumulative distribution functions are still significant. The ratio between the modelled Dragons and Black Swans can reach up to only 10%. It is much less than 30%, which was the level established for observations.
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