21 research outputs found
Carbon emission and export from the Ket River, western Siberia
Get PDFDespite recent progress in the understanding of the carbon (C) cycle of Siberian permafrost-affected rivers, spatial and seasonal dynamics of C export and emission from medium-sized rivers (50 000-300 000 km2 watershed area) remain poorly known. Here we studied one of the largest tributaries of the Ob River, the Ket River (watershed Combining double low line 94 000 km2), which drains through pristine taiga forest of the boreal zone in the West Siberian Lowland (WSL). We combined continuous and discrete measurements of carbon dioxide (CO2) concentration using submersible CO2 sensor and floating chamber flux (FCO2), with methane (CH4), dissolved organic and inorganic C (DOC and DIC, respectively), particulate organic C and total bacterial concentrations over an 800 km transect of the Ket River main stem and its 26 tributaries during spring flood (May 2019) and 12 tributaries during summer baseflow (end of August-beginning of September 2019). The partial pressure of CO2 (pCO2) was lower and less variable in the main stem (2000 to 2500 μatm) compared to that in the tributaries (2000 to 5000 μatm). In the tributaries, the pCO2 was 40 % higher during baseflow compared to spring flood, whereas in the main stem, it did not vary significantly across the seasons. The methane concentration in the main stem and tributaries was a factor of 300 to 1900 (flood period) and 100 to 150 times lower than that of CO2 and ranged from 0.05 to 2.0 μmol L-1. The FCO2 ranged from 0.4 to 2.4 g C m-2 d-1 in the main channel and from 0.5 to 5.0 g C m-2 d-1 in the tributaries, being highest during August in the tributaries and weakly dependent on the season in the main channel. During summer baseflow, the DOC aromaticity, bacterial number, and needleleaf forest coverage of the watershed positively affected CO2 concentrations and fluxes. We hypothesize that relatively low spatial and seasonal variability in FCO2 of the Ket River is due to a flat homogeneous landscape (bogs and taiga forest) that results in long water residence times and stable input of allochthonous dissolved organic matter (DOM), which dominate the FCO2. The open water period (May to October) C emission from the fluvial network (main stem and tributaries) of the Ket River was estimated to 127 ± 11 Gg C yr-1, which is lower than the downstream dissolved and particulate C export during the same period. The estimated fluvial C emissions are highly conservative and contain uncertainties linked to ignoring hotspots and hot moments of emissions, notably in the floodplain zone. This stresses the need to improve the temporal resolution of FCO2 and water coverage across seasons and emphasizes the important role of WSL rivers in the release of CO2 into the atmosphere
Element transport in the Taz River, western Siberia
Get PDFThe riverine export fluxes of dissolved carbon, nutrient and metals from the land to the Arctic Ocean are fairly well quantified for five large Arctic rivers but remain virtually unknown for mid-sized Eurasian rivers, notably those draining through the permafrost zone. Because such rivers can most rapidly respond to on-going climate warming and permafrost thaw in the Arctic, their current hydrochemical composition and elemental yields are badly needed for judging the level of changes in the very near future. Towards quantifying the annual export fluxes and assessing the mechanisms of seasonal variability of river solutes, we monitored the pristine subarctic Taz River (Swatershed = 150,000 km2), which drains through boreal forest and peatlands in the discontinuous and continuous permafrost zone, on a weekly to monthly basis over a 3 year period. Based on seasonal pattern of riverine solutes (70% of annual Mn flux occurred in winter. A number of elements present in the snowpack exhibited sizable (> 45%) export during spring flood (Zn, Cu, Pb, Cd, Sb and Cs). The 3 years mean export fluxes (yields) of dissolved components were comparable to or 30–50% lower than those of other large and medium sized Arctic rivers. This was due mostly to a lack of fresh unaltered rocks and a dominance of peatlands within the Taz River watershed. Elevated concentrations of redox-sensitive micro-nutrients (such as Fe and Mn) occurring during winter baseflow can be linked to disproportionally large floodplain zone of this river which can act, especially in the river's lower reaches, as a stratified lake thereby releasing high amounts of redox-sensitive elements from the sediments. The role of suboxic zones in the Arctic boreal riverine landscape may be more important than previously thought, and may allow explaining anomalously high concentrations of some metals (i.e., Mn) reported in Arctic Ocean surface waters. It is anticipated that climate warming in the region may increase the contribution of winter flow and enhance the export of soluble elements and some nutrients (such as Si, Mn and Co)
Problems of Control and Information Theory
Get PDF1982 / 1. szám
Falin, G. I.: Enlargement of states of symmetric system with limited availability
Zadorozhnii, A. I. - Chernyakov, M. V. - Povarenkin, V. I.: Optimal signal processing in asynchronous address data transmission systems under narrow-band noises
Danilov, N. N.: Principles of optimality in cooperative differential games with nontransferable pay-offs
Sher, A. P.: Algorithmic methods for fuzzy set selection via non-point expert estimates
Levin, V. I.: Perelroizen, E. Z.: Space scene computer perception
Hangos, K. M.: On the ARMAX-type system properties affecting the quality of control by discrete tune invariant minimum variance regulation
1982 / 2. szám
Doležal, J.: Necessary optimality conditions for a class of nondifferentiable discrete control problems
Kleimenov, A. F.: Equilibrium coalitional mixed strategies in differential games of m players
Pethő, A. - Reményi, Gy.: On a method for establishing the minimum distance of Abelian codes
Mazurov, V. D. - Frolov, V. N. - Satchkov, N. O.: On some procedures of production optimization including identification of restrictions
Spal, J.: Applications of modified fuzzy sets
Medvedev, V. S. - Puzanov, V. P.: Splinefunction application for the optimization of the programmed control of dynamic systems
1982 / 3. szám
Tretyakov, V. E.: A stochastic program approximation of a value of a determinate positional differential game
Filipiak, J.: Optimization of dynamic flows in networks of hierarchical structure
Hangos, K. M.: Sensitivity of discrete linear stochastic systems with respect to parameter variations of their discrete linear regulator
Pakshin, P. V.: Optimal linear control of discrete-time systems with random jump parameters
Sinha, N. K. - El-Nahas, I. - Alden, R. T. H.: Routh approximation of multivariable systems
Kopysov, O. Yu. - Prokopov, E. I. - Pupkov, K. A.: Identification of parameters and the state of one class of nonlinear systems
Pátek, B.: On the robustness of minimum distance decoding
Fifth All-Union Conference on Statistical Methods in Control Theory
Book review
1982 / 4. szám
Yemelyanov, S. V. -Korovin. S. K. - Sizikov, V. I.: Control of nonstationary plants with coordinate-parametric and parametric feedbacks
Krasovskii, N. N. - Tret'jakov, V. E.: Control solution with optimal ensured result
Botkin. N. D.: Evaluation of numerical construction error in differential game with fixed terminal time
Doležal, J.: On the problem of necessary conditions for static minmax problems
Ahlswede, R.: Remarks on Shannon's secrecy systems
Khachatrian, G. G.: On the construction of codes for noiseless synchronized 2-user channel
Kutoyants, Yu. A.: Multidimensional parameter estimation of the intensity function of inhomogeneous Poisson processes
1982 / 5. szám
Ahlswede, R. - Dueck, G.: Bad codes are good ciphers
Poltyrev, G. Sh.: Tightness of the random coding bounds for broadcast channels
Dyachkov, A. G. - Poltyrev, G. Sh.: Error probability asymptotics for an ensemble of codes with dependent codewords
Nikol'skii, M. S.: Stroboscopical strategies and the first direct method of L. S. Pontrjagin in quasilineas nonstationary differential games of pursuit-evading
Bakule, L.: On a new hierarchical structure for large-scale systems design
Bouchon, B. - Cohen, G. - Frankl, P.: Metrical properties of fuzzy relations
1982 / 6. szám
Vaněček, A.: State space construction of recursive identification
Siluyanova, I. D.: The finite-dimensional distributions o the outputs of one class of non-linear systems
Botkin, N. D. - Patsko, V. S.: Universal strategy in a differential game with fixed terminal time
Nguyen Quang A.: Estimating the transmission delay in queueing type packet concentrators with finite buffer size
Shin, V. I.: Decomposition of non-linear stochastic systems described by differential equations
Hrušák, J. - Mošna, J. - Janeček, E. - Šimandl, m.: Strip.thickness adaptive control for cold-rolling mill
High riverine CO2 emissions at the permafrost boundary of Western Siberia
Get PDFAcknowledgements: The study was part of the JPI Climate initiative, financially supported by VR (the Swedish Research Council) grant no. 325-2014-6898 to J.K. Additional funding from RNF (RSCF) grant no. 18-17-00237, RFBR grant no. 17-55-16008 and RF Federal Target Program RFMEFI58717X0036 ‘Kolmogorov’ to O.S.P. and S.N.K. as well as NERC grant no. NE/M019896/1 to C.S. is acknowledged. The authors thank A. Sorochinskiy and A. Lim for assistance in the field, as well as M. Myrstener, M. Klaus and S. Monteux for advice on data analysis. L. Kovaleva is acknowledged for artwork.Peer reviewe
Trace element transport in western Siberian rivers across a permafrost gradient
No full textTowards a better understanding of trace element (TE) transport in
permafrost-affected Earth surface environments, we sampled ∼ 60 large and small rivers (< 100 to ≤ 150 000 km2
watershed area) of the Western Siberian Lowland (WSL) during
spring flood and summer and winter baseflow across a 1500 km latitudinal
gradient covering continuous, discontinuous, sporadic and permafrost-free
zones. Analysis of ∼ 40 major and TEs in the dissolved
(< 0.45 µm) fraction allowed establishing main environmental
factors controlling the transport of metals and TEs in rivers of
this environmentally important region. No statistically significant effect
of the basin size on most TE concentrations was evidenced.
Two groups of elements were distinguished: (1) elements that show the same
trend throughout the year and (2) elements that show seasonal differences.
The first group included elements decreasing northward during all seasons
(Sr, Mo, U, As, Sb) marking the underground water influence of river
feeding. The elements of the second group exhibited variable behavior in the
course of the year. A northward increase during spring period was mostly
pronounced for Fe, Al, Co, Zn and Ba and may stem from a combination of
enhanced leaching from the topsoil and vegetation and bottom waters of the
lakes (spring overturn). A springtime northward decrease was observed for
Ni, Cu, Zr and Rb. The increase in element concentration northward was observed for Ti, Ga, Zr and Th only in
winter, whereas Fe, Al, rare earth elements (REEs), Pb, Zr, and Hf
increased northward in both spring and winter, which could be linked to
leaching from peat and transport in the form of Fe-rich colloids. A
southward increase in summer was strongly visible for Fe, Ni, Ba, Rb and V,
probably due to peat/moss release (Ni, Ba, Rb) or groundwater feeding (Fe,
V). Finally, B, Li, Cr, V, Mn, Zn, Cd, and Cs did not show any distinct trend
from S to N.
The order of landscape component impact on TE concentration in rivers was
lakes > bogs > forest. The lakes decreased export of
Mn and Co in summer and Ni, Cu, and Rb in spring, presumably due to biotic
processes. The lakes enriched the rivers in insoluble lithogenic elements in
summer and winter, likely due to TE mobilization from unfrozen mineral
sediments. The rank of environmental factors on TE concentration in western
Siberian rivers was latitude (three permafrost zones) > season
> watershed size. The effect of the latitude was minimal in
spring for most TEs but highly visible for Sr, Mo, Sb and U. The main factors
controlling the shift of river feeding from surface and subsurface flow to
deep underground flow in the permafrost-bearing zone were the depth of the
active (unfrozen) seasonal layer and its position in organic or mineral
horizons of the soil profile. In the permafrost-free zone, the relative role
of carbonate mineral-bearing base rock feeding versus bog water feeding
determined the pattern of TE concentration and fluxes in rivers
of various sizes as a function of season.
Comparison of obtained TE fluxes in WSL rivers with those of other subarctic
rivers demonstrated reasonable agreement for most TEs; the
lithology of base rocks was the major factor controlling the magnitude of TE
fluxes. Climate change in western Siberia and permafrost boundary
migration will essentially affect the elements controlled by underground
water feeding (DIC, alkaline earth elements (Ca, Sr), oxyanions (Mo, Sb, As)
and U). The thickening of the active layer may increase the export of
trivalent and tetravalent hydrolysates in the form of organo-ferric
colloids. Plant litter-originated divalent metals present as organic
complexes may be retained via adsorption on mineral horizon. However, due to
various counterbalanced processes controlling element source and sinks in
plant–peat–mineral soil–river systems, the overall impact of the
permafrost thaw on TE export from the land to the ocean may be smaller than
that foreseen with merely active layer thickening and permafrost boundary
shift
Problems of Control and Information Theory
Get PDF1980 / 1. szám
Pospelov, D. A.: Artificial intelligence systems. Results and short-term outlook
Gel'fand, S. I. - Pinsker, M. S.: Coding for channel with random parameters
Kárný, M.: Bayesian estimation of model order
Emelyanov, S. V.: Sliding mode application in the problems of multifold optimal differentiation
Kumar, K. S. P. - Griffith, E. W.: Observability of nonlinear systems
Levin, V. I.: Logical design of an algorithm for optimization of technological process parameters
1980 / 2. szám
Emel'yanov, S. V. - Korovin, S. K. - Rykov, A. S.: Local optimal simplex precision of direct search
Mareš, M.: Transformations of general coalition-games
Grebenyuk, E. A.: Stochastic automata using supplementary information during learning
Raczyński, S.: On nonconvex control in a separable Banach space
Vajda, I.: Adaptive Gaussian detection without a priori symbol synchronization
Topencharov, V.: Peeva, K.: Mathematical automata theory: a categorical approach
1980 / 3. szám
Krasovskii, N. N.: Stochastic control with a guaranteed result
Khazen, E. M.: Observed data reduction and risk increase estimates in sequential analysis
Kowalewski, A. - Kotarski, W.: Application of Milutin-Dubovicki's method to solving an optimal control problem for hyperbolic systems
Prokopov, B. I. - Kopysov, O. U.: About modal control of linear time-invariant object with unknown parameters
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International Colloquium on Information Theory
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1980 / 4. szám
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Grigoriev, A. A.: The transforms of the shift register sequences
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1980 / 5. szám
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1980 / 6. szám
Boris Nikolaevich Petrov (1913-1980)
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Klein, P. - Doležal, J.: A mathematical model of antibody response dynamics
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Book revie
A snap-shot assessment of carbon emission and export in a pristine river draining permafrost peatlands (Taz River, Western Siberia)
No full textWe acknowledge support from the TSU Development Program “Priority-2030”, the RSF grant No. 22-17-00253, and grant “Kolmogorov” of MES (Agreement No. 075-15-2022-241). SV is grateful to support from URI “System of experimental bases located along the latitudinal gradient TSU (Agreement No. 0.75-15-2021-672). We thank Sergey Kopysov for providing the discharge data and Olga Moreva for help with nutrient analyses.International audienceMobilization of dissolved organic carbon (DOC) and CO 2 from the frozen peat to surface waters in the permafrost zone of high latitude regions is expected to enhance under on-going permafrost thaw and active layer thickness deepening. Here we explored one of the most remote, pristine, unregulated and yet environmentally important rivers in western Siberia (Taz). This subarctic river drains through forested and tundra peat bogs over a gradient of permafrost and climate and likely acts as an important conduit of CO 2 to the atmosphere and carbon and nutrient exporter to the Arctic Ocean. In a snapshot study during end of spring flood–beginning of summer baseflow (July 2019), we monitored daytime CO 2 and CH 4 concentrations and measured CO 2 emissions using floating chambers in the main stem (700 km from the upper reaches to the mouth) and 16 main tributaries and we also assessed day/night variations in the emissions. We further tested the impact of land cover parameters of the watershed and tributaries. Based on regular monitoring of the terminal (gauging) station, we quantified the C export to the Arctic Ocean during the study period. We revealed sizable CO 2 emissions from the main stem and tributaries (1.0 ± 0.4 and 1.8 ± 0.6 g C-CO 2 m −2 d −1 , respectively). The CO 2 concentrations positively correlated with dissolved organic carbon (DOC), whereas the CH 4 concentrations could be partially controlled by dissolved nutrients (N, P) and proportion of light coniferous forest at the watershed. The overall C emission from the water surfaces (4,845 km 2 ) of the Taz basin (150,000 km 2 ) during open water period (6 months, May to October) was estimated as 0.92 Tg C (>99.5% C-CO 2 , <0.5% C-CH 4 ) which is twice higher than the total dissolved C (organic and inorganic) riverine export flux during the same period. Applying a “substituting space for time” approach for northern and southern parts of the river basin, we suggest that the current riverine CO 2 emission may increase 2 to 3 fold in the next decades due to on-going climate warming and permafrost thaw. When integrating the obtained results into global models of C and biogeochemical cycle in the Arctic and subarctic region, the use of the Taz River as a representative example of continental planes should help to estimate the consequences of frozen peatland thaw on CO 2 cycle in the Arctic and subarctic regions
