12. Chemofossils in cover sediments of the eastern Eurasian part of the arctic shelf – origin, sources, interpretation (on the material of scientific cruises 2000-2005)
V.I. Petrova, A.V. Kursheva, I. Litvinenko
T. Alexeeva, A. Timofeeva
An accurate representation of sea ice concentration is valuable to operational ice analysis, process studies, model inputs, and detection of long-term climate change. In this study we compared the available visual shipborne and satellite datasets. Special ice observations have been carried out since 1995 during 15 expeditions to the Russian Arctic seas. These data were compared to the Special Sensor Microwave/Imager (SSM/I) satellite data for the same periods in the Barents, Kara, Laptev and East Siberian seas. SSM/I images obtained by the NASA Team and Artist Sea Ice algorithms were used for comparison.In the present report statistical analyses are presented for algorithms for summary results, separately for summer and winter seasons, for different ice conditions, and for total ice concentration including or excluding new ice forms. As well, we estimated the influence of the melting stage in order to find a possible source of errors in satellite data.
G. Fedorov, A. Gorodinskiy, P. Vahrameeva
Russia The main goal of our project was the reconstruction of the Holocene environmental history of Kanin Peninsula and of the environmental history for the last few hundred years for the entire Barents Sea region based on lake sediment core studies. All our cores were opened, logged in detail and sampled during the reported period. Unfortunately, not all expected analyses were possible to proceed because of limited analyses conditions. Nevertheless, the samples for spore-pollen analysis were already prepared and diatom analysis of samples from 4.3 m long sediment cores from Lake Kamennoe (Kanin Peninsula) was carried out. Based on diatom analysis we can conclude that the core from Kamennoe Lake covers the entire lake history and most of the Holocene.
I. Fedorova, E. Grigorieva, A. Chetverova
The activity of hydromorphodynamic processes along the Lena River delta, grounding field observations and long-term water discharge variability allow determining the future transformation of the Lena River delta under hydrodynamic conditions and to obtain features of liquid and solid matter accumulation and outflow processes. We focused on the next stage of research based on the results obtained during expeditions to the Lena River delta, which were supported by tOSL and DAAD grants in 2004-2006, and in the frame of the on-going joint Russian-German investigations on water, suspended, and dissolved substances runoff to the Laptev Sea. Due to coastal dynamics in the Laptev Sea there are some changes in the hydromorphodynamic conditions in the Lena Delta, where runoff and lithological transformations take place. Some sections of the modern delta have morphological features characteristic for advancing shores, others show signs of retreat. In the high-water period, channels in the delta can have a nontrivial liquid and suspended matter runoff that indicates the erosion rate. The Lena River has a positive trend of annual runoff. The interaction of shelf and river water off the channels has an effect on external sedimentation and accumulation. The study of actives processes and trends allows forecasting the delta evolution in the near future.
S. Kirillov, M. Makhotin, E. Chernyavskaya
The recently occuring climatic changes make the Arctic region dramatically sensitive to these changes due to the polar amplification. The so-called „global warming" anomaly is evident here in earlier ice melting and ice retreating in summer; in positive surface layer water temperature anomalies; delay in ice formation and thermal erosion of the coastline. Dealing with Siberian Arctic shelves hydrography we demonstrate that the climatic changes produce well pronounced transitions in freshwater and heat budgets at the shallows. It was found that summer and winter salinities over the eastern Siberian Arctic shelves (Laptev, East-Siberian and Chukchi seas) continuously freshen, while the Kara Sea is evident to become more saline since the 1960s. The seasonal signal in salinity decreases due to decreasing net sea-ice export to the Arctic Ocean during winter season. The principal scheme of annual salinity cycle was constructed to be consistent with the observed changes.
T. Kuznetsova, I. Chursina, E. Baikina
We focused on the study of indicators of terrestrial palaeoenvironmental conditions (mammals, diatoms, spore and pollen, rhizopods, ostracods) as highly accurate markers of the changing terrestrial environmental conditions. The investigations have been carried out since 1998 in the frame of the Russian-German cooperation „Laptev Sea System" and OSL Fellowship programs.Using new investigation methods we reconstructed extinct animals such as woolly mammoth and woolly rhinoceros (by ancient DNA) and paleoenvironmental conditions (by different stable isotopes). We analyzed vast macro and micropaleontological, palynological, geological and taphonomic data from the Laptev Sea region and reconstructed terrestrial palaeoenvironmental changes in different regions of the Laptev Sea surroundings during the Late Pleistocene and Holocene.All data about Late Quaternary dynamic terrestrial biome in this region are new.
Methane-derived authigenic carbonates (MDAC) associated with gas hydrates from the Derugin Basin (NE Sakhalin Island, Sea of Okhotsk) were investigated in detail during several cruises of the R/V „Akademik M.A. Lavrentyev" (in 2003, 2005 & 2006). Numerous MDAC with different morphology were found in the sediments of the gas hydrate-bearing structures related to gas discharge on the seafloor: Obzhirov, KOPRI, POI, VNIIOkeangeologia, Hieroglyph, Giselle, CHAOS, KIT, Kitami, Katyusha, Soloviev, Dungeon and several unnamed structures. Based on the morphology and density, carbonates formations can be classified into four main groups: 1. represented by poorly consolidated, fragile (type 1a) or soft isolations (type 1b), homogeneous in color (light green); the inclusions represent the initial stage of the carbonate formation; 2. dense dendritic-like concretions or those of elongated shape which sometimes have numerous protuberances; 3. concretions with rounded or subangular shape, dense and having the same zoning as the second group; 4. tubicolous carbonates formed by substitution of Polychaeta worms or burrows. All carbonate types are composed mainly of Mg-calcite. Based on the carbon-oxygen isotopic composition of MDAC, we assume that (1) the gas involved in their and gas hydrate formation has different sources and (2) the relative quantities of these gases are responsible for the variations in the isotope composition. The application of the corrections for the MDAC allowed to estimate the age of the studied clam shells as Holocene (max to 4.0 ka BP), whereas the established radiocarbon ages of these shells vary from 13.46 to 2.14 ka BP.
New data about geomorphological structure of the Lena River delta was obtained during the grant period. Therefore, the PhD thesis „Geomorphologic structure of the Lena River delta and its development during the Holocene" was renamed into „Laptev Sea level fluctuation as a factor of formation of the Lena River delta during the Holocene". All practical work has already been done and results have been obtained. The thesis will be finished at the beginning of November. The results presented in the thesis are:• only the first Lena River delta terrace was formed by the river, the second and third terraces – now becoming erosion relics – were formed by other agents;• the first terrace of the Lena River delta is composed of „peaty" sediments which deposited in the paleobasin;• the first terrace of the Lena River delta was formed by repeated Laptev Sea level rising during the Holocene;• the repeated Laptev Sea level rises during the Holocene reached a height of 10 m above the m.s.l. maximum.
A. Makshtas, R. Vlasenkov, A. Pavlov
New Secchi disc data and sea water samples for investigation of suspended matter concentrations (289 samples) and color dissolved organic matter (207 samples), together with data about the meteorological conditions and global solar radiation, were collected during an expedition of R/V „Ivan Petrov" to the eastern Barents, Kara, and Laptev Seas (July – November 2007). Laboratory analysis of water samples on the concentration of suspended matter was executed with OSL equipment (total number of samples: 289). A comparison of the data about the concentration of suspended matter with data of turbidity measurements allowed developing new dependences between these characteristics in different areas of the investigated seas and to compile detailed maps of spatial distributions of suspended matter concentration and PAR extinction coefficient in the study areas with hydrosound „Sea-Bird SBE19plus" data. Using data of 261 hydrological stations of the 2007 expedition, where turbidity was measured in 0.4 m steps, three-dimensional maps of the spatial distribution of suspended matter concentration in the Kara and Laptev Seas were established Laboratory analysis of water samples on the CDOM concentration was conducted and the spatial distribution of CDOM in the study areas was reconstructed. A set of historical Secchi disc data for the Kara and Chukchi Seas was created and the radiation characteristics and concentration of suspended matter, calculated with this data, gave the possibility to investigate its long-term temporal-spatial variability for all Russian shelf seas (Kara, Laptev, East-Siberian and Chukchi Seas) for the first time. Based on spectral measurements, the relation between PAR and global solar radiation was established for the study area for the first time. A draft for a paper about hydro-optical properties of the Laptev and East-Siberian Seas was prepared.
D. Martynova, N. Kazus', N. Mingazov
The present project revealed feeding peculiarities and morphological parameters of Calanus glacialis, inhabiting both low-Arctic and high-Arctic areas, in close connection with possible climate change. The importance of both algal and non-algal particles in the diets of C. glacialis CIV-CVI copepodits was asserted. Thoroughly performed morphological and population analysis vs preferable depths revealed a possible dependence of animals on food availability during spring (May) and on the temperature conditions in the summer time in the White Sea.A significant dependence of female gonad maturation time on food availability and quality was revealed. This is to some extent in contrast to previous theoretical assessments on the life cycle strategies of this species and thus proves strong interactions between reproduction peculiarities and climate change.An extremely low abundance of C. glacialis was observed during analysis of the sediment traps from the Fram Strait, which is possibly caused by an increasing inflow of North Atlantic waters into this region and thus substitution of the Arctic species C. glacialis by the Atlantic one Calanus finmarchicus.
L. Mazurenko/T. Matveeva, P. Rekant, E. Beketov
The study of gas venting in the Laptev Sea (and formation of gas hydrates) is presented in the context of global climate changes. The main goals of the study were to estimate the scale of gas venting in the Laptev Sea and to consider conditions of gas hydrate formation-decomposition. More than 70 gas seeps were identified in the study area on the basis of high-resolution seismic profiles interpretation. The gas seepage structures on the seismic record represented gas chimneys and gas flashes of various sizes. The depths of the gas penetration are different suggesting different intensities of the gas fluxes. Most of the seeps occur outside of the gas hydrate stability zone (GHSZ) for methane hydrates. However, high contents of heavy hydrocarbons in the sediments and seeps were identified on the seismic records at four sites occurring within the GHSZ suggesting their possible relation to hydrate formation. Our observations together with the fact that most of the gas manifestations on the seismic profiles do not reach the seafloor suggest that the gas emission was not triggered by gas hydrate decomposition and, therefore, the contribution of the emitted gas to global warming seems to be of minor influence at present.
Our work was devoted to the reconstructions of postglacial environments in the White Sea region. Newly revealed relations of aquatic palynomorphs formation in the surface sediments and their relation to modern hydrological and sea-ice conditions in the White Sea were used for paleoenvironmental reconstructions in the postglacial time period. The cysts of autotrophic species, which almost universally dominate in the surface sediments, reflect the hydrological conditions in the White Sea favorable for their development during the vegetation period.The distinctive features of the postglacial development of the White Sea were determined by the consistent degradation of the Scandinavian ice sheet during the Late Pleistocene and Holocene and by the increasing advection of the Barents Sea waters. On the basis of previous geological and micropaleontological (diatoms, pollen and spores) investigations of numerous sediment cores from the White Sea, the general stratigraphical scheme was elaborated. Unfortunately, this scheme has not been supported by radiocarbon data until now. In this report, we present the first radiocarbon and radiochronology data obtained for sediment cores from the White Sea and paleoenvironmental reconstructions based on distribution patterns of aquatic palinomorph assemblages in the White Sea sediments. Our research of dinoflagellate cyst assemblages was devoted to high-resolution reconstructions of the variations in compositions of marine microflora in post glacial sediments. Micropaleontological investigations of sediment cores gave new opportunities to reconstruct the ice-hydrological conditions of sedimentation in the White Sea basin during the Holocene. Strongly dominating autotrophic species were found in the warm periods of the Holocene. The obtained results are in good correlation with the common stratigraphic scheme used to describe the White Sea sediments.
V.I. Petrova, A.V. Kursheva, I. Litvinenko
The lithological-geochemical characteristics and distribution of chemofossils and organic matter (OM) in surface bottom sediments of the Laptev and the East Siberia seas were analyzed, with the goal to identify the sources and pathways of OM found in these seas. The composition and distribution of OM in eastern Arctic shelf were found to be similar to those typical for the Arctic shelf and ocean at whole. The distribution of total organic carbon (TOC), humid acids, bitumoids and hydrocarbons in the Siberian shelf sediments confirms the important role of river water. In contrast, the presence of inorganic carbon is due to the influence of Atlantic water mass flowing along the continental slope.
I. Polovodova, A. Nikulina
A survey of recent benthic foraminiferal assemblages and sediment geochemistry was conducted in the Kiel Fjord during 2005-2007. Labile organic compounds in surface sediments showed strong seasonal variability with higher values in springtime. In Friedrichsort Sound low levels of nutrients were found. In general, the surface sediment pollution by Cu, Zn, Sn and Pb was considered as moderate, whereas the inner fjord still undergoes a high load of heavy metals in spite of a decline of shipyards activity. The foraminiferal population density showed a response to food availability triggered by SiO2 and Chl a contents in the sediments. An increase of population density and changes in species composition since the 1960s were detected. A. beccarii, a highly stress-tolerant species, invaded the Kiel Fjord. Able to withstand higher water turbulences, E. albiumbilicatum inhabits the transitional area of the Friedrichsort Sound. Unfavourable salinity conditions in the Kiel Bight apparently caused the diminution of A. cassis. Increase in abundance of abnormal foraminiferal tests correlated to high trace-metal levels during springtime. This was explained by reproduction of benthic foraminifera during spring bloom and especially the high sensitivity of juveniles to environmental stress. A sediment core with good preserved sediment layers taken in the outer Kiel Fjord was sampled for retrospective analysis of environmental changes. The calculation of the sedimentation rate was based on measurements of lead-210 and cesium-137 activity. The irregular distribution of 210Pb activity downcore requires additional calculations based on the sediment density according to the constant rate of supply (CRS) model. The dating by 210Pb was verified with a 137Cs profile. In the Kiel Fjord we detected two cesium activity peaks, presumably orginating from 1986 and 1963. The peak depths indicated unstable sedimentation rates in the core: the upper part from the 1980s on has a rate of about 1 mm/year and from the 1960s to the 1980s it was about 1.3 mm/year, what is generally conformed to the rates estimated for sandy-muds of the western Baltic Sea. Analyses of Corg, TC and TN distributions downcore were done. The increase of organic carbon and total nitrogen in the 1960s with a following decrease in the 1970s was related to the establishment of the sewage treatment plant Bülk in 1972. Further analyses of pigments and biogenic silica downcore will explain whether primary production increase and oxygen deficiency took place. Ongoing analysis of the downcore sediments for benthic foraminifera and the trace metals Cu, Zn, Pb and Sn will help us to detect the trend of pollution by harbours and shipyards thriven in the 20th century.
Ye.I. Polyakova, T.S. Klyuvitkina, L. Astakhova
The main goals of our study were (i) to reveal the peculiarity of species composition and productivity of sea-ice microalgae in phytoplankton and sea-ice communities from the Laptev Sea polynya area, (ii) and to establish major regularities in distribution patterns of sea-ice indicated species of diatoms and dinocysts in the Laptev Sea surface sediments and theirs relationship with novel sea-ice indicated organic compound (IP25) for the reconstructions of past sea-ice conditions in the Arctic seas. On the basis of the study of Laptev Sea surface sediment samples the following results were achieved: (i) a profound relationship between sea ice diatom distribution patterns (concentrations of diatom valves in sediments and their relative abundances in the surface sediment assemblages) and IP25 values was revealed; (ii) a sharp increase in both IP25 values and sea-ice diatoms northward of the mean interannual location of the polynya was observed; (iii) a steep increase in abundances of sea-ice-associated species of dinocysts seaward of the mean interannual position of the polynya area along with concentrations of heterotrophic species of dinocysts was marked. According to our study the phytoplankton in the western Laptev Sea and the eastern Kara Sea was dominated by diatoms and dinoflagellates in August 2007. The total biomass of phytoplankton in the western Laptev Sea was low with relatively high abundances of phototrophic species of dinoflagellates. In the Kara Sea the phytoplankton mainly consisted of heterotrophic dinoflagellates. Four types of phytoplankton communities were defined on the basis of species composition and biomasses of microalgae. The occurrence of ice-neritic species was possibly caused by the influence of water mass from the northern Laptev Sea covered by pack ice during this time.
According to the research plan the investigator of the project completed a study of four cores from the Laptev Sea shelf and the continental slope. On the basis of pollen and spore records from AMS14-dated cores and boreholes obtained from the Laptev Sea shelf during the TRANSDRIFT expeditions, major phases of the Late Pleistocene and Holocene vegetation changes associated with the last postglacial global sea-level rise were recognized by the investigator of the current project for the western and eastern Laptev Sea region. According to pollen data from the western part of the Laptev Sea (PS-51-154-11, PS-51-159-10) the vegetation development experienced rapid changes during the time period from 15.2 thousand years to 9.6 thousand years ago. Plant communities changed from relict ones to warmest tundra landscapes. The maximum Holocene warming appearantly occurred around 10.3-8.5 thousand years ago. Starting from the period of 6.3 thousand years ago (PS-51-080-13, PS-51-092-13) the climate conditions became modern-like. The vegetation cover was characterized by modern tundra landscapes. Pollen data from the eastern part of the Laptev Sea (PS-092-13, PS-080-13) reveal slight fluctuations in the vegetation cover during the Holocene period from 6.5 ka on. A slight cooling was noticed since around 3 thousand years ago.
P. Semenov, E. Bazhenova, M. Kuznetsova
Samples were collected during three expeditions: Barents Sea samples in a coastal zone of the Kola-Kanin Monocline (June 2007, RV „Ivan Petrov"), Kara Sea samples in the coastal zone of Yugor Peninsula (August 2007, RV „Ivan Petrov"), and Yugor Peninsula coast samples (Shpindler site, July 2007). Investigations fulfilled in the framework of the project implied two basic directions: the study of coastal processes intensity and element transport into the sea as a result of coastal abrasion and gas geochemistry of the southwestern Kara Sea with focus on methane discharge. This approach enabled us to establish and estimate the basic trends of environmental geochemistry of the southwestern Kara Sea. The volume and balance of different substances released by coastal abrasion was estimated with the following conclusions: the volume of oxygen consumed during permafrost degradation in the Arctic coastal zone is comparable to that obtained by water photolysis in the upper layer of the atmosphere, which is the main abiogenic source of oxygen atmospheric input; the intensive consumption of oxygen for oxidation of released low-valent elements (Fe2+) leads to the development of anaerobic processes in the coastal zone. The comparison of the rate of past coastal degradation to the contemporary one indicates that the increase of the coastal retreat amounts to one order.Detailed investigations of gaseous HC (hydrocarbons) composition were carried out. Gas anomalies providing quite high concentrations of methane were found in the near-shore areas of southwestern Kara Sea: around Shpindler site and east of Vaigach Island at the mouth of Baidaratskaya Bay. The synthesis of different data gives us a basis to suppose that the gases detected in the sampling area are unlikely to be a result of in-situ microbial production.
V. Shevchenko, N. Goryunova, M. Stoikin
In the project aeolian and ice transport as well as fluxes of matter in the Arctic environment were studied. These studies were carried out in the frame of the International Polar Year 2007/2008. The balance calculations show that the contribution of aerosols to sediment formation in the Arctic is close to the contribution of river particulate matter beyond the marginal filters of rivers. For many chemical elements (Pb, Sb, Se, V etc.) the aeolian source is the primary one. Based on geochemical studies and analyses of back trajectories of air masses we determined the main local pollution sources (Norilsk, Monchegorsk, Vorkuta etc.) in pollutant delivery to the Arctic. Snow chemistry is an important indicator of aeolian transport of many chemical elements and compounds. In some locations of the southeastern part of the Beaufort Sea aeolian dust in snow possibly has an Asian source. The drifting ice accumulates airborne materials (including ecotoxicants) and transports them to the ice melting areas. The elemental composition of lichens, mosses and peat reflects the aeolian delivery of many elements.
E. Taldenkova, Ya. Ovsepyan, A. Strezh
The project aimed at reconstructing postglacial and Holocene inflows of Atlantic-derived water masses to the Laptev Sea and their interactions with the local meltwater and riverine freshwater outflows through a high-resolution study of microfossils (foraminifers and ostracods) and lithology of marine sediments (percentage of >63 µm fraction, IRD counts). The previously obtained record of Atlantic-derived waters inflows and past environmental changes based on analysis of kasten core sequences has been supplemented by the detailed investigation of core catchers PS51-154 (extrapolated age 17.1-17.6 cal.ka), PS51-159 (12.2-12.6 cal.ka) and PS51-135 (11.3-11.4 cal.ka). Occassional subsurface inflows of Atlantic-derived waters were reconstructed for the time period 17.6-15.6 cal.ka with the strongest event at 17.1 cal.ka evidenced by an extremely high total abundance of small-sized planktic foraminifers dominated by diverse subpolar species. A steady subsurface inflow of Atlantic-derived waters was revealed since 15.6 cal.ka. It was enhanced between 15.6 and 12 cal.ka and after 5.5 cal.ka. Two periods of enhanced IRD input correspond to the times of deglaciation and Barents-Kara ice sheet retreat at ca. 17.6-16 cal.ka and Mid-Late Holocene climate cooling and Severnaya Zemlya ice cap growth after 7 cal.ka. The obtained results were summarized in 4 papers for Russian and international journals.