Lichen, moss and peat control of C, nutrient and trace metal regime in lakes of permafrost peatlands

Shirokova, Liudmila S.; Chupakov, Artem V.; Иванова, И. С.; Moreva, Olga Y.; Zabelina, Svetlana A.; Shutskiy, Nikita A.; Loiko, Sergey V.; Pokrovsky, Oleg S.

doi:10.1016/j.scitotenv.2021.146737

Cited by 27 publications

(16 citation statements)

References 84 publications

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“…Digital assessments of the morphological and hydraulic properties of Sphagnum and lichens of the Western Siberian Lowlands presented in this work, suggest extremely porous, connected media with high specific surfaces and high hydraulic conductivities. These results are in line with the biogeochemical observations of Shirokova et al (2021), demonstrating the overwhelming role of Sphagnum mosses in organic carbon, nutrient and inorganic solute fluxes in the Western Siberian Lowlands. Nonetheless, discrepancies between the numerical results presented in this work (Fig.…”

Section: Discussionsupporting

confidence: 90%

“…This cryptogamic layer has an important impact on permafrost dynamics because it influences heat and water exchanges between the soil and atmosphere (Soudzilovskaia et al, 2013;Launiainen et al, 2015;Porada et al, 2016;Park et al, 2018;Loranty et al, 2018). Boreal vegetation is assumed to be a major nutrient and inorganic solute exchange medium at a watershed scale (Shirokova et al, 2021). Boreal vegetation is likely to accumulate in lowlands at a low degradation rate, resulting in the formation of Sphagnum peatlands, such as the Western Siberian Lowlands.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Assessment of Morphological and Hydraulic Properties of Moss, Lichen and Peat from a Permafrost Peatland

Cazaurang

Marcoux²,

Pokrovsky³

et al. 2022

Preprint

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Abstract. The hydraulic properties of ground vegetation cover are important for high resolution hydrological modeling of permafrost regions, due to its insulating and draining role. In this study, the morphological and effective hydraulic properties of Western Siberian Lowland ground vegetation samples (lichens, Sphagnum mosses, peat) are numerically assessed based on tomography scans. After numerical pre-processing, porosity is estimated through a void voxels counting algorithm, showing the existence of representative elementary volumes (REV) of porosity for most samples. Then, two methods are used to estimate hydraulic conductivity depending on the sample’s homogeneity. For the most homogeneous samples, Direct Numerical Simulations (DNS) of a single-phase flow are performed, leading to a definition of hydraulic conductivity related to REV, which is larger than those obtained for porosity. For more heterogeneous samples, no adequate REV may be defined. To bypass this issue, a pore network representation of the whole sample is created from computerized scans. Morphological and hydraulic properties are then estimated through this simplified representation. Both methods converged on similar results for porosity. Some discrepancies are observed in the morphological properties (specific surface area). Hydraulic conductivity fluctuates by two orders of magnitude, depending on the method used, and yet this uncertainty is less than that found in experimental studies. Therefore, biological and sampling artifacts are predominant over numerical biases. Porosity values are in line with previous values found in the literature, showing that arctic cryptogamic cover can be considered as an open and well-connected porous medium (over 99 % of overall porosity is open porosity). Meanwhile, digitally estimated hydraulic conductivity is higher compared to previously obtained results based on field and laboratory experiments. This could be related to compressibility effects, occurring during field or laboratory measurements. Thus, some supplementary studies are compulsory for assessing syn-sampling and syn-measurement perturbations in experimentally estimated, effective hydraulic properties of such a biological porous medium.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of Morphological and Hydraulic Properties of Moss, Lichen and Peat from a Permafrost Peatland

Cazaurang

Marcoux²,

Pokrovsky³

et al. 2022

Preprint

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“…Finding a recalcitrant DOM pool at the end of 495 the winter is not surprising. As winter goes by, water gets more depleted in labile material, consumed first and foremost, while fresh inputs of carbon are impeded by the ice-cover, the frozen surrounding soils, and the absence of primary production in the lake and on land (Deshpande et al, 2016;Przytulska et al, 2016;Shirokova et al, 2021). Overall, this is consistent with studies on peatland water generally reporting low bacterial growth efficiencies (i.e.…”

supporting

confidence: 84%

“…Berggren et al, 2007;Shirokova et al, 2019). By comparison, bacterial activity was clearly higher 500 when supplied with fresh plant leachates (Shirokova et al, 2021). The abundance of low-quality substrates in peatland water may be related to the dominance of Sphagnum mosses at the study sites.…”

mentioning

confidence: 78%

The dominant role of sunlight in degrading winter dissolved organic matter from a thermokarst lake in a subarctic peatland

Mazoyer

Laurion

Rautio

2022

Preprint

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Abstract. Dissolved organic matter (DOM) leaching from thawing permafrost may promote a retroaction loop onto climate if it is efficiently mineralized into greenhouse gases. Yet, many uncertainties remain on the extent of this mineralization, which depends on DOM lability that is seemingly quite variable across landscapes. Thermokarst peatlands are organic-rich systems where some of the largest greenhouse gas (GHG) emission rates have been measured. At spring turnover, anoxic waters are releasing the GHG accumulated in winter, and the DOM pool is being exposed to sunlight. Here, we present an experiment where DOM photo- and bioreactivity were investigated in water collected from a thermokarst lake in a subarctic peatland during late winter (after six months of darkness). We applied treatments with or without light exposure, and manipulated the bacterial abundance with the aim to quantify the unique and combined effects of light and bacteria on DOM reactivity at ice-off in spring. We demonstrate that sunlight was clearly driving the transformation of the DOM pool, partly leading to its full mineralization into CO2. About 18 % of initial dissolved organic carbon (DOC, a loss of 3.9 mgC L−1) was directly lost over 18 days of sunlight exposure in a treatment where bacterial abundance was initially reduced by 95 %, while dark incubations lead to very limited changes in DOC, regardless of the bacterial abundance and activity. The highest DOC loss was observed for the treatment with the full bacterial community exposed to sunlight (5.0 mgC L−1), indicating an undirect effect of light through the bacterial consumption of photoproducts. Sunlight was an outstanding boosting factor on bacterial growth when grazers were eliminated, leading to the recovery of the original bacterial abundance in about 8 days. The results also show that only half of the light-associated DOC losses were converted into CO2, with the rest potentially turned into particles through photo-flocculation. Sunlight should therefore play a major role in DOM processing, CO2 production and carbon burial in peatland lakes during spring, likely lasting for the rest of the open-season in mixing surface layers.

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“…The greatest species diversity of zooplankton was recorded in small lakes (up to 0.02 km 2 ). It is possible that highest DOC concentration in small thaw ponds due to cpastal peat abrasion and ground vegetation leaching [52] provides high amount of fresh and relatively bioavailable organic substrates [81] and this can lead to high diversification of heterotrophic bacterial population, which, in turn, can serve as diverse food substrates for various group of phytoplankton. Further, we found a decrease in zooplankton biodiversity and an increase in the degree of dominance of one species with an increase in the area of lakes.…”

Section: Discussionmentioning

confidence: 99%

Environmental Factors Controlling Zooplankton Communities in Thermokarst Lakes of the Bolshezemelskaya Tundra Permafrost Peatlands (NE Europe)

Sobko¹,

Shirokova²,

Klimov³

et al. 2022

Preprint

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Environmental physical and chemical factors controlling the abundance and biodiversity of zooplankton in permafrost-affected lakes are poorly known yet they determine the response of the ecosystems to on-going climate change and water warming. Here we assessed the current status of zooplankton communities of lake ecosystems in the North-West of the Bolshezemelskaya tundra (Nenets Autonomous district), and provide new information about the composition and structure of zooplankton. Results demonstrate that the structure of zooplankton communities is influenced by morphometric features of lakes and the degree of their overgrowth by macrophytes. According to the level of zooplankton development, most tundra lakes were of the oligotrophic type with an average biomass of up to 1 g/m3. The largest number of species was observed in zooplankton communities of small lakes with an area of up to 0.02 km2 and overgrown with macrophytes. The analysis of factors that influence the formation of the lakes zoocenosis demonstrated that the species composition and quantitative characteristics of zooplankton are chiefly controlled by pH and water mineralization. A comparison of the results obtained with the literature data on the lakes of this region collected 60 years ago confirms that the ecosystems of the studied lakes are in a stable state. Overall, these new insights will improve our knowledge of factors controlling the zooplankton spatial dynamics in unique but quite abundant thermokarst lakes of NE European Tundra, subjected to on-going climate warming.

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Lichen, moss and peat control of C, nutrient and trace metal regime in lakes of permafrost peatlands

Cited by 27 publications

References 84 publications

Numerical Assessment of Morphological and Hydraulic Properties of Moss, Lichen and Peat from a Permafrost Peatland

Numerical Assessment of Morphological and Hydraulic Properties of Moss, Lichen and Peat from a Permafrost Peatland

The dominant role of sunlight in degrading winter dissolved organic matter from a thermokarst lake in a subarctic peatland

Environmental Factors Controlling Zooplankton Communities in Thermokarst Lakes of the Bolshezemelskaya Tundra Permafrost Peatlands (NE Europe)

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