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Shiping Wei, Hongpeng Cui, Youhai Zhu, Zhenquan Lu, Shouji Pang, Shuai Zhang, Hailiang Dong, Xin Su
Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number...
February 10, 2018: Extremophiles: Life Under Extreme Conditions
Mark J Lara, Ingmar Nitze, Guido Grosse, Philip Martin, A David McGuire
Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity...
February 5, 2018: Scientific Reports
Stephen J Cox, Diana J F Taylor, Tristan G A Youngs, Alan K Soper, Tim S Totton, Richard G Chapman, Mosayyeb Arjmandi, Michael G Hodges, Neal Skipper, Angelos Michaelides
Natural gas hydrates occur widely on the ocean-bed and in permafrost regions, and have potential as an untapped energy resource. Their formation and growth, however, poses major problems for the energy sector due to their tendency to block oil and gas pipelines, while their melting is viewed as a potential contributor to climate change. Although recent advances have been made in understanding bulk methane hydrate formation, the effect of impurity particles, which are always present under conditions relevant to industry and the environment, remains an open question...
February 5, 2018: Journal of the American Chemical Society
Carolin Kindler, Eva Graciá, Uwe Fritz
Extra-Mediterranean glacial refugia of thermophilic biota, in particular in northern latitudes, are controversial. In the present study we provide genetic evidence for extra-Mediterranean refugia in two species of grass snake. The refuge of a widely distributed western European lineage of the barred grass snake (Natrix helvetica) was most likely located in southern France, outside the classical refuges in the southern European peninsulas. One genetic lineage of the common grass snake (N. natrix), distributed in Scandinavia, Central Europe and the Balkan Peninsula, had two distinct glacial refuges...
January 29, 2018: Scientific Reports
Andreas Westergaard-Nielsen, Mojtaba Karami, Birger Ulf Hansen, Sebastian Westermann, Bo Elberling
Temperature changes in the Arctic have notable impacts on ecosystem structure and functioning, on soil carbon dynamics, and on the stability of permafrost, thus affecting ecosystem functions and putting man-built infrastructure at risk. Future warming in the Arctic could accelerate important feedbacks in permafrost degradation processes. Therefore it is important to map vulnerable areas most likely to be impacted by temperature changes and at higher risk of degradation, particularly near communities, to assist adaptation to climate change...
January 25, 2018: Scientific Reports
Matthias Winkel, Julia Mitzscherling, Pier P Overduin, Fabian Horn, Maria Winterfeld, Ruud Rijkers, Mikhail N Grigoriev, Christian Knoblauch, Kai Mangelsdorf, Dirk Wagner, Susanne Liebner
Thawing submarine permafrost is a source of methane to the subsurface biosphere. Methane oxidation in submarine permafrost sediments has been proposed, but the responsible microorganisms remain uncharacterized. We analyzed archaeal communities and identified distinct anaerobic methanotrophic assemblages of marine and terrestrial origin (ANME-2a/b, ANME-2d) both in frozen and completely thawed submarine permafrost sediments. Besides archaea potentially involved in anaerobic oxidation of methane (AOM) we found a large diversity of archaea mainly belonging to Bathyarchaeota, Thaumarchaeota, and Euryarchaeota...
January 22, 2018: Scientific Reports
Weihua Wang, Tonghua Wu, Lin Zhao, Ren Li, Changwei Xie, Yongping Qiao, Huiwen Zhang, Xiaofan Zhu, Shuhua Yang, Yanhui Qin, Junming Hao
Ground ice is a distinctive feature of permafrost terrain. The vertical distribution and factors controlling the hydrochemistry of ground ice are important for studying soil moisture and salt migration during the freeze-thaw process in soil. These factors are also important components of hydrological cycles in cold regions. The hydrochemical characteristics of ground ice on the Qinghai-Tibetan Plateau (QTP) are not well known. We examined the characteristics of ground ice hydrochemistry using data from 9 soil profiles in permafrost regions of the central QTP...
January 16, 2018: Science of the Total Environment
Katy J Sparrow, John D Kessler, John R Southon, Fenix Garcia-Tigreros, Kathryn M Schreiner, Carolyn D Ruppel, John B Miller, Scott J Lehman, Xiaomei Xu
In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon...
January 2018: Science Advances
Lauren E Kipp, Matthew A Charette, Willard S Moore, Paul B Henderson, Ignatius G Rigor
Rising temperatures in the Arctic Ocean region are responsible for changes such as reduced ice cover, permafrost thawing, and increased river discharge, which, together, alter nutrient and carbon cycles over the vast Arctic continental shelf. We show that the concentration of radium-228, sourced to seawater through sediment-water exchange processes, has increased substantially in surface waters of the central Arctic Ocean over the past decade. A mass balance model for 228Ra suggests that this increase is due to an intensification of shelf-derived material inputs to the central basin, a source that would also carry elevated concentrations of dissolved organic carbon and nutrients...
January 2018: Science Advances
Binu Mani Tripathi, Mincheol Kim, Yongwon Kim, Eunji Byun, Ji-Woong Yang, Jinho Ahn, Yoo Kyung Lee
Understating the microbial communities and ecological processes that influence their structure in permafrost soils is crucial for predicting the consequences of climate change. In this study we investigated the bacterial and archaeal communities along depth profiles of four soil cores collected across Alaska. The bacterial and archaeal diversity (amplicon sequencing) overall decreased along the soil depth but the depth-wise pattern of their abundances (qPCR) varied by sites. The community structure of bacteria and archaea displayed site-specific pattern, with a greater role of soil geochemical characteristics rather than soil depth...
January 11, 2018: Scientific Reports
Rafael Gonçalves-Araujo, Benjamin Rabe, Ilka Peeken, Astrid Bracher
As consequences of global warming sea-ice shrinking, permafrost thawing and changes in fresh water and terrestrial material export have already been reported in the Arctic environment. These processes impact light penetration and primary production. To reach a better understanding of the current status and to provide accurate forecasts Arctic biogeochemical and physical parameters need to be extensively monitored. In this sense, bio-optical properties are useful to be measured due to the applicability of optical instrumentation to autonomous platforms, including satellites...
2018: PloS One
Shira Houwenhuyse, Emilie Macke, Lien Reyserhove, Lore Bulteel, Ellen Decaestecker
Current natural populations face new interactions because of the re-emergence of ancient microbes and viruses. These risks come from the re-emergence of pathogens kept in laboratories or from pathogens that are retained in the permafrost, which become available upon thawing due to climate change. We here focus on the effects of such re-emergence in natural host populations based on evolutionary theory of virulence and long-term studies, which investigate host-pathogen adaptations. Pathogens tend to be locally and temporally adapted to their co-occurring hosts, but when pathogens from a different environment or different time enter the host community, the degree to which a new host-pathogen interaction is a threat will depend on the specific genotypic associations, the time lag between the host and the pathogen, and the interactions with native or recent host and pathogen species...
January 2018: Evolutionary Applications
Jun-Jian Wang, Melissa Lafrenière, Scott Lamoureux, Andre J Simpson, Yves Gélinas, Myrna J Simpson
Regional warming has caused permafrost thermokarst and disturbances, such as active layer detachments (ALDs), which may alter carbon feedback in Arctic ecosystems. However, it is currently unclear how these disturbances alter DOM biogeochemistry in rivers and ponds in Arctic ecosystems. Water samples from main channel, ALD-disturbed/undisturbed tributaries, and disturbed/undisturbed ponds within a catchment of Canadian High Arctic were collected and analyzed using carbon isotopes and spectroscopic methods. Both river and pond samples had large variations in dissolved organic carbon (DOC) concentrations...
January 4, 2018: Environmental Science & Technology
Guibiao Yang, Yunfeng Peng, David Olefeldt, Yongliang Chen, Guanqin Wang, Fei Li, Dianye Zhang, Jun Wang, Jianchun Yu, Li Liu, Shuqi Qin, Tianyang Sun, Yuanhe Yang
Permafrost thaw alters the physical and environmental conditions of soil and may thus cause a positive feedback to climate warming through increased methane emissions. However, the current knowledge of methane emissions following thermokarst development is primarily based on expanding lakes and wetlands, with upland thermokarst being studied less often. In this study, we monitored the methane emissions during the peak growing seasons of two consecutive years along a thaw sequence within a thermo-erosion gully in a Tibetan swamp meadow...
December 25, 2017: Environmental Science & Technology
Daan Blok, Samuel Faucherre, Imre Banyasz, Riikka Rinnan, Anders Michelsen, Bo Elberling
Tundra regions are projected to warm rapidly during the coming decades. The tundra biome holds the largest terrestrial carbon pool, largely contained in frozen permafrost soils. With warming, these permafrost soils may thaw and become available for microbial decomposition, potentially providing a positive feedback to global warming. Warming may directly stimulate microbial metabolism but may also indirectly stimulate organic matter turnover through increased plant productivity by soil priming from root exudates and accelerated litter turnover rates...
December 13, 2017: Global Change Biology
Liming Tian, Lin Zhao, Xiaodong Wu, Hongbing Fang, Yonghua Zhao, Guojie Hu, Guangyang Yue, Yu Sheng, Jichun Wu, Ji Chen, Zhiwei Wang, Wangping Li, Defu Zou, Chien-Lu Ping, Wen Shang, Yuguo Zhao, Ganlin Zhang
Soil nutrient stoichiometry and its environmental controllers play vital roles in understanding soil-plant interaction and nutrient cycling under a changing environment, while they remain poorly understood in alpine grassland due to lack of systematic field investigations. We examined the patterns and controls of soil nutrients stoichiometry for the top 10cm soils across the Tibetan ecosystems. Soil nutrient stoichiometry varied substantially among vegetation types. Alpine swamp meadow had larger topsoil C:N, C:P, N:P, and C:K ratios compared to the alpine meadow, alpine steppe, and alpine desert...
December 4, 2017: Science of the Total Environment
Shuhong Zhang, Guangli Yang, Shugui Hou, Tingjun Zhang, Zhiguo Li, Feng Liang
Antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) can be identified with metagenomic analyses comparing relatively pristine and human-impacted environments. We collected samples from 3 different environments: glacial soil little affected by anthropogenic activity, deep permafrost dated to 5821 BP (before human antibiotics), and sediment from the Pearl River. Sulfonamides, tetracyclines, and fluoroquinolones were common in the sediment samples. Sulfonamides and tetracycline were not found in permafrost; tetracycline was also not found in glacial soil...
November 28, 2017: Environmental Pollution
Sophie Crevecoeur, Warwick F Vincent, Jérôme Comte, Alex Matveev, Connie Lovejoy
Lakes and ponds derived from thawing permafrost are strong emitters of carbon dioxide and methane to the atmosphere, but little is known about the methane oxidation processes in these waters. Here we investigated the distribution and potential activity of aerobic methanotrophic bacteria in thaw ponds in two types of eroding permafrost landscapes in subarctic Québec: peatlands and mineral soils. We hypothesized that methanotrophic community composition and potential activity differ regionally as a function of the landscape type and permafrost degradation stage, and locally as a function of depth-dependent oxygen conditions...
2017: PloS One
Kun Xiao, Changchun Zou, Zhenquan Lu, Juzhi Deng
Accurate calculation of gas hydrate saturation is an important aspect of gas hydrate resource evaluation. The effective medium theory (EMT model), the velocity model based on two-phase medium theory (TPT model), and the two component laminated media model (TCLM model), are adopted to investigate the characteristics of acoustic velocity and gas hydrate saturation of pore- and fracture-filling reservoirs in the Qilian Mountain permafrost, China. The compressional wave (P-wave) velocity simulated by the EMT model is more consistent with actual log data than the TPT model in the pore-filling reservoir...
November 24, 2017: Scientific Reports
Boris P Ilyashuk, Elena A Ilyashuk, Roland Psenner, Richard Tessadri, Karin A Koinig
A global warming-induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide-bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year...
November 15, 2017: Global Change Biology
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