Research of throwing areols of underground pipeline in permafrost

Study is due to the possibility of loss of stability of the pipeline in the process of pumping a product with a positive operating temperature and the formation of thawing halos. The article presents the ways of solving the thermomechanical problem of pipeline displacement due to thawing. The rate of formation of a thawing halo is investigated depending on the initial temperatures of the soil and the pumped product. The developed monitoring system makes it possible to study the rate of occurrence of thawing halos in the process of pumping the product. An experimental study on the formation of thawing halos around the pipeline was carried out on an experimental model. A thermophysical comparative calculation of temperatures around the pipeline on a model by the finite element method has been carried out. Keywords: underground pipeline; permafrost; thawing halo; monitoring; operating conditions; stress–strain state.

Simulation of heat transfer with considering permafrost thawing in 3D media

An approach to mathematical modeling of heat transfer with a permafrost algorithm in 3D media based on the idea of localizing the phase transition area is considered. The paper presents a problem statement for a non-stationary heat transfer and a description of a numerical method based on a predictor-corrector scheme. For a better understanding of the proposed splitting method, the accuracy order of approximation considering inhomogeneous right-hand side was studied. The phase changes in the numerical implementation of permafrost thawing is considered in the temperature range and requires recalculation of coefficients values of the heat equation at each iteration step with respect to time. A brief description of the parallel algorithm based on a 3D decomposition method and the parallel sweep method is presented. A study of the parallel algorithm implementations using a high-performance computing system of the Siberian Supercomputer Center of the SB RAS was performed. The results of the permafrost algorithm on models with wellbores are also presented.

Uphill Shifts of Fungal Fruiting Due to Climate Change at the Polar Urals

Due to the ongoing climatic changes in the Arctic, the ranges of many plants and animal species are rising higher into the mountains, into the treeline; however, such studies are rare for fungi. The 60-year fruiting dynamics of 66 species of Agaricomycetous macrofungi has been studied along the altitudinal transect located on the slope of Slantsevaya Mountain (Polar Urals, Russia). It has been found that the three basic trophic groups (mycorrhizal, saprobes on litter and soil, and saprobes on wood) fruit higher in the mountains. Additionally, for most of the studied species, a tendency towards upward displacement of fruiting was revealed. The rise in fruiting for saprobes on litter and soil was the most obvious. Mycorrhizal fungi associated with woody plants showed the least uplifting effect. Fungal species that were characterized by fruiting higher up the mountainside half a century ago show stronger upward shifts compared to species previously bearing fruit only at the mountain foot. Probably, such a reaction of the aboveground mycobiota is similar to the processes occurring in the soil, which are associated with an active increase in the decomposition rate of the litter, an increase in the depth of permafrost thawing, and a significant redistribution of the soil water balance. On the other hand, the rise of fungi is associated with an increase of plant biomass in the middle and upper parts, which are the most important sources of fungal nutrition.

Deciphering the Palaeocene–Eocene thermal maximum by Granger causality test

The Palaeocene–Eocene thermal maximum is a global warming period (~ 56 Ma), which is marked by a sharp negative carbon isotope excursion (CIE) that caused by the injection of massive isotopically-light carbon into the ocean-atmosphere. It is often considered that the carbon injection caused global warming. However, several studies have suggested that warming and environmental perturbations precede the onset of the CIE. Here we present Granger test to investigate the detailed mechanisms of this event. We show a shift from climate-warming driving carbon-emission scenario to a scheme in which carbon-injection causing global-warming during the CIE. The initial carbon emission might be from methane hydrates dissociation and/or permafrost thawing, possibly linked with astronomical paced warming. This change of causal direction may result from the warming feedback of the emitted carbon and additional carbon from other sources, such as volcanism, bolide impact, oxidation of marine organic matter, and wildfires burning peatlands.

Review Article: Permafrost Trapped Natural Gas in Svalbard, Norway

Permafrost has become an increasingly important subject in the High Arctic archipelago of Svalbard. However, whilst the uppermost permafrost intervals have been well studied, the processes at its base and the impacts of the underlying geology have been largely overlooked. More than a century of coal, hydrocarbon and scientific drilling through the permafrost interval shows that accumulations of natural gas trapped at the base permafrost is common. They exist throughout Svalbard in several stratigraphic intervals and show both thermogenic and biogenic origins. These accumulations combined with the relatively young permafrost age indicate gas migration, driven by isostatic rebound, is presently ongoing throughout Svalbard. The accumulation sizes are uncertain, but one case demonstrably produced several million cubic metres of gas over eight years. Gas encountered in two boreholes on the island of Hopen appears to be situated in the gas hydrate stability zone and thusly extremely voluminous. While permafrost is demonstrably ice-saturated and acting as seal to gas in lowland areas, in the highlands it appears to be more complex, and often dry and permeable. Svalbard shares a similar geological and glacial history with much of the Circum-Arctic meaning that sub-permafrost gas accumulations are regionally common. With permafrost thawing in arctic regions, there is a risk that the impacts of releasing of sub-permafrost trapped methane is largely overlooked when assessing positive climatic feedback effects.

Metal accumulation capacity in indigenous Alaska vegetation growing on military training lands

Permafrost thawing could increase soil contaminant mobilization in the environment. Our objective was to quantify metal accumulation capacities for plant species and functional groups common to Alaskan military training ranges where elevated soil metal concentrations were likely to occur. Plant species across multiple military training range sites were collected. Metal content in shoots and roots was compared to soil metal concentrations to calculate bioconcentration and translocation factors. On average, grasses accumulated greater concentrations of Cr, Cu, Ni, Pb, Sb, and Zn relative to forbs or shrubs, and bioconcentrated greater concentrations of Ni and Pb. Shrubs bioconcentrated greater concentrations of Sb. Translocation to shoots was greatest among the forbs. Three native plants were identified as candidate species for use in metal phytostabilization applications. Elymus macrourus, a grass, bioconcentrated substantial concentrations of Cu, Pb, and Zn in roots with low translocation to shoots. Elaeagnus commutata, a shrub, bioconcentrated the greatest amounts of Sb, Ni, and Cr, with a low translocation factor. Solidago decumbens bio-concentrated the greatest amount of Sb among the forbs and translocated the least amount of metals. A combination of forb, shrub, and grass will likely enhance phytostabilization of heavy metals in interior Alaska soils through increased functional group diversity.

Thermal Bridging Through Branches of Snow-Covered Shrubs Cool Down Permafrost in Winter

Warming-induced shrub expansion on Arctic tundra (Arctic greening) is thought to warm up permafrost by several degrees, as shrubs trap blowing snow and increase snowpack thermal insulation, limiting permafrost winter cooling and facilitating its thaw. At Bylot Island, (Canadian high Arctic, 73°N) we monitored permafrost temperature at nearby unmanipulated herb tundra and shrub tundra sites and unexpectedly observed that low shrubs cool permafrost by 1.21°C over the November-February period. This is despite a snowpack twice as insulating in shrubs. Using heat transfer models and finite-element simulations, we show that this winter cooling is caused by thermal bridging through frozen shrub branches. This effect largely compensates the warming effect induced by the more insulating snow in shrubs. The cooling is partly canceled in spring when shrub branches under snow absorb solar radiation and accelerate permafrost warming. The overall effect is expected to depend on snow and shrub characteristics and terrain aspect. These significant perturbations of the permafrost thermal regime by shrub branches should be considered in projections of permafrost thawing, nutrient recycling and greenhouse gas emissions.

Isotope Signs (234U/238U, 2H, 18O) of Groundwater: An Investigation of the Existence of Paleo-Permafrost in European Russia (Pre-Volga Region)

The isotopic (234U/238U, 2H, 18O) and chemical composition of groundwater on the right bank of the Volga River along the middle reach (European Russia) was studied down to a depth of 400 m. These data allow diagnosis of the presence of a three-component mixture. The first component is modern/young fresh recharge water of the Holocene age. It has the isotopic composition of water δ18O → −12.9 ‰ and δ2H → −90 ‰, close to modern precipitations, and the equilibrium isotopic composition of uranium 234U/238U → 1 (by activity). The second component is slightly salted water of the late or postglacial period with δ18O → −17.0 ‰ and δ2H → −119 ‰, and a small excess of uranium-234 234U/238U ≈ 4. The third component is meltwater formed as result of permafrost thawing. It is brackish water with δ18O ≈ −15.0 ‰ and δ2H ≈ −110 ‰, and a maximum excess of uranium-234 234U/238U ≈ 15.7. The salinity of this water is associated with an increase of the SO42−, Ca2+ and Na+ content, and this may be due to the presence of gypsum in water-bearing sediments, because the solubility of sulfates increases at near-zero temperature. We explain the huge excess of uranium-234 by its accumulation in the mineral lattice during the glacial age and quick leaching after thawing of permafrost.