S. P. Davydov

Grain‐size properties and organic‐carbon stock of Yedoma Ice Complex permafrost from the Kolyma lowland, northeastern Siberia

The organic carbon stock in permafrost is of increasing interest in environmental research, because during the late Quaternary a large pool of organic carbon accumulated in the sedimentary deposits of arctic permafrost. Because of its potential to degrade and release organic carbon, the organic-matter inventory of Yedoma Ice Complex deposits is relevant to current concerns about the effects of global warming. In this context, it is essential to improve the understanding of preserved carbon quantities and characteristics. The paper aims to clarify the Yedoma Ice Complex origin, and to develop an approach for volumetric organic-matter quantification. Therefore, we analyzed the grain size and the organic-matter characteristics of the deposits exposed at the stratigraphic key site Duvanny Yar (lower Kolyma River, northeast Siberia). A distinct bimodal grain-size distribution confirms a polygenetic origin of the frozen sediments from a flood-plain environment. The total organic-carbon content averages 1.5 ± 1.4 wt% while the volumetric organic-carbon content averages 14 ± 8 kg/m³. However, large-scale extrapolations for Yedoma Ice Complex deposits in general are not reasonable yet because of their rather unclear spatial distribution. We conclude that Yedoma Ice Complex formation at Duvanny Yar was dominated by water-related (alluvial/fluvial/lacustrine) as well as aeolian processes. The total organic-carbon content of the studied deposits is low if compared to other profiles, but it is still a significant pool.

A high-resolution time series of oxygen isotopes from the Kolyma River: Implications for the seasonal dynamics of discharge and basin-scale water use

ntensification of the Arctic hydrologic cycle and permafrost melt is expected as concentrations of atmospheric greenhouse gases increase. Quantifying hydrologic cycle change is difficult in remote northern regions; however, monitoring the stable isotopic composition of water runoff from Arctic rivers provides a means to investigate integrated basin-scale changes. We measured river water and precipitation δ18O and δD to partition the river flow into snow and rain components in the Kolyma River basin. On an annual basis, we found water leaving the basin through the river consisted of 60% snow and 40% rain. This is compared with annual precipitation inputs to the watershed of 47% snow and 53% rain. Despite the presence of continuous permafrost, and fully frozen soils in the spring, our analysis showed not all spring snowmelt runs off into the river immediately. Instead, a substantial portion is retained and leaves the basin as growing season evapotranspiration.

Flux of methane from north siberian aquatic systems: Influence on atmospheric methane

The sizes of major sources and sinks of atmospheric methane, an important greenhouse gas, are poorly known. Our results indicate that all major aquatic habitats of northeast Siberia are potential sources of diffusive and ebullition flux of CH4 to the atmosphere, particularly in winter, and that much of this flux derives from terrestrial carbon that accumulated in loess sediments during the Pleistocene. These data provide evidence that northern aquatic sediments are a large enough winter CH4 source to explain the observed winter increase in atmospheric CH4 at high northern latitude.The clear positive relationship between active thermokarst and measured ebullition rates suggests that long-term changes in CH4 ebullition from Siberian aquatic systems will be most strongly influenced by thermokarst erosion rates.

Siberian tundra ecosystem vegetation and carbon stocks four decades after wildfire

Tundra ecosystem fire regimes are intensifying with important implications for regional and global carbon (C) and energy dynamics. Although a substantial portion of the tundra biome is located in Russia, the vast majority of accessible studies describe North American tundra fires. Here we use field observations and high-resolution satellite remote sensing observations to describe the effects of wildfire on ecosystem C pools and vegetation communities four decades after fire for a tundra ecosystem in northeastern Siberia. Our analyses reveal no differences between soil physical properties and C pools in burned and unburned tundra, which we attribute to low combustion of organic soil associated with low-severity fire. Field and remote sensing data show no differences in aboveground C pools and vegetation communities indicating recovery to prefire conditions. These results are comparable to observations of ecosystem recovery in North American tundra. An assessment of literature data indicate that the average annual area burned in Russian tundra is an order of magnitude larger than that of Alaskan tundra, highlighting a crucial need to assess Russian tundra fire regimes in order to understand the current and future role of the biome wide fire regime in regional and global C and energy dynamics.

Preliminary Study of a Mummified Woolly Rhinoceros from the Lower Reaches of the Kolyma River

Blum., 1799) (Fig. 1) wasfound on the right bank of the Lower Kolyma River, ina gold field at the upper reaches of the Malaya Filip-pova River (8 km east of the village of Cherskii of theNizhnekolymskii District of Yakutia). We studied theburial place on October 10, 2007, and the specimen inMarch, 2008, as it was brought to the MammothMuseum of the Institute of Applied Ecology of North,Yakutsk (IPES). Most of the mummified corpse waspreserved, including the left half of the trunk, with skinof the head and ear, the skull with the lower jaw, thefore and hind legs (Figs. 1–3). Small bunches of shortcoarse light brown wool are only preserved on lowersites of legs. The right side of the body and the rightlegs are lost (apparently, cut off by a bulldozer). Mostof the inner organs are lost; however, intestine is prob-ably partially preserved. The same locality has yielded anumber of specimens isolated from the trunk, i.e., the rightpelvis, the lower part of the right hind leg with soft tissues(Fig. 3b), and bones of the right foreleg (humerus, ulna,carpals, metacarpals, and two ungual phalanges). Hornshave not been found. The fragmentary genitals preservedin the specimen show that this is a female.The body measurements of this individual are ratherlarge, close to those of other adult female woolly rhi-noceroses (Table 1) [1]; the specimen weighs about900 kg; hence, during its life, the animal was about1.5 tons. The parietal length of the skull is 763 mm, thezygomatic width is 332 mm, the length of the uppertooth row is 217 mm. The mandible from the symphysisto the posterior edge of the articular process is 562 mmlong, the tooth row is 212 mm long, the ascendingramus measured from the apex of the articular processis 265 mm high. The teeth has wear signs; the majorsutures on the skull are obliterated; the nasal septum iscompletely ossified. These features, along with thebody and skull measurements, strongly suggest that therhinoceros from the vicinity of the village of Cherskiiwas an adult.The locality is situated on the left slope of east expo-sition at approximately 130 m above sea level. Thebone-bearing bed is at a depth of 5–9 m, composed offrozen dark gray loam of the Edoma Formation (glacialassemblage), with ice interbeds. Mostly loose, icy Qua-ternary deposits at the upper reaches of the Malaya Fil-ippova River form the strata about 15–17 m thick. Theburial place is at the junction of the northeastern part ofthe Kolyma Lowland and hilly spurs of the Anui Pla-teau, at about 200–630 m above sea level. According tothe soil geographical zonation, the area under study isat the boundary of the forest–tundra plain and theAlazeya–Yukagir plateau–tundra–taiga province of thetundra–forest subzone. Recent soils at the upperreaches of the Malaya Filippova River are formed oftypical cryogenic and taiga permafrost soils with vary-ing peaty and gleyey admixture. They show a high con-tent of organic matter, loamy particle-size distribution,neutral and subacid reaction, and high enzymaticpotential. Vegetation in the area studied belongs to thethin northern larch forest subzone [2]. In elevated sites,this is light larch forest, frequently with continuousmossy–lichen cover, dense undergrowth of five or sixwillow species, dwarf and Middendorf’s birches, inplaces, Manchurian alder, abundant low shrubs, andwith a small admixture of grasses and forbs. Hills arecovered with the dwarf stone pine. Lowered areas fre-quently have marshy moss–frutescent or grass–mossyopen woodlands.Paleoecological conditions in the habitat of theKolyma rhinoceros was reconstructed based on palyno-logical analysis; the ground sample comes from pri-

Study of Pollen and Spores from the Stomach of a Fossil Woolly Rhinoceros Found in the Lower Reaches of the Kolyma River

E). A study of the stomach contentsof the fossilized rhinoceros using palynological methods with the aim of establishing the particularities of itsdiet and recreating the paleofloristic conditions of theperiod of its existence was of great interest.A sample of the remnants of the stomach lump ofthe woolly rhinoceros was characterized by a high concentration of pollen and spores (more than1700 micrograins in one preparation). Most pollengrains were very well preserved.In the general spectrum, the pollen of grass plantspredominates (98.5%). Pollen from trees and bushesaccounts of 0.9%, and 0.6% are represented by spores(Table 1). The grass pollen composition is mainlyaccounted for by the pollen of Gramineae (45.9%)and Compositae (40.6%), in which wormwood pollendominates (40.1%). Up to 10 varieties of pollen can bedistinguished in the Gramineae pollen by morphological characteristics. They differ in size, grain shape,pore, and exine structure, etc. It is very difficult toclassify the Gramineae pollen down to the specieslevel, and this has not been done yet. Nonetheless,judging by the morphological particularities of thepollen, it can be assumed that it belongs to differentGramineae species. Wormwood pollen is also represented by various species; on the basis of its morphology, we assume that it is composed of

The transitional climate of the late Miocene Arctic: Winter-dominated precipitation with high seasonal variability

The late Miocene (11.6–5.3 Ma) was an important transitional period following the greenhouse conditions of the Eocene. In order to gain insight into the Arctic paleoclimate of the time, we performed high-resolution intraring δ 13 C analyses on fossil wood collected from the late Miocene Khapchansky sediments of northeastern Siberia (∼69°N). From these data we quantified the ratio of summer to winter precipitation (Ps/Pw) and compared it to current values for the region determined from modern wood samples and instrumental records. We observed much greater frequency of winter-dominated precipitation (Ps/Pw < 1) and much greater variability in Ps/Pw during the Miocene than today. Specifically, years with Ps/Pw < 1 occurred three times more often, and years with at least three times as much precipitation in summer or winter (0.33 < Ps/Pw < 3.0) occurred approximately twice as often during the Miocene than today. We attribute the high interannual variability in precipitation to an inconsistent moisture source associated with the relatively unstable and incomplete ice cover in the Arctic Ocean during the late Miocene. Our result highlights the potential for enhanced variability in Arctic precipitation in response to Arctic sea ice decline caused by anthropogenic, CO 2 -induced warming.

Initial data on biological activity of taiga–steppe soils in the lower reaches of the Kolyma River

Microbiological and enzyme activities of extrazonal taiga-steppe soils in the lower reaches of the Kolyma River have been studied for the first time. Contrary to north-taiga cryometamorphic soils, predominating in the area, microbial cenoses under herb–sedge petrophytic and grass–sagebrush–herb thermophytic steppes are characterized by features typical for arid soils. The saturation of the soil profile with microorganisms is greater, and the development of actinomycetes is more intensive. The enzyme complex is characterized by high activity of dehydrogenases.