DOCSLIB.ORG

Carbon Transport by the Lena River from Its Headwaters to the Arctic Ocean, with Emphasis on fluvial Input of Terrestrial Particulate Organic Carbon Vs

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Carbon Transport by the Lena River from Its Headwaters to the Arctic Ocean, with Emphasis on fluvial Input of Terrestrial Particulate Organic Carbon Vs Biogeosciences, 8, 2407–2426, 2011 www.biogeosciences.net/8/2407/2011/ Biogeosciences doi:10.5194/bg-8-2407-2011 © Author(s) 2011. CC Attribution 3.0 License. Carbon transport by the Lena River from its headwaters to the Arctic Ocean, with emphasis on fluvial input of terrestrial particulate organic carbon vs. carbon transport by coastal erosion I. P. Semiletov1,2, I. I. Pipko2, N. E. Shakhova1,2, O. V. Dudarev2, S. P. Pugach2, A. N. Charkin2, C. P. McRoy1, D. Kosmach2, and O.¨ Gustafsson3 1International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775, USA 2Laboratory of Arctic Studies, Pacific Oceanological Institute, Far-Eastern Branch of Russian Academy of Sciences, Vladivostok 690041, Russia 3Stockholm University, Department of Applied Environmental Science and the Bert Bolin Centre for Climate Research, Stockholm, Sweden Received: 12 February 2011 – Published in Biogeosciences Discuss.: 3 March 2011 Revised: 15 August 2011 – Accepted: 23 August 2011 – Published: 2 September 2011 Abstract. The Lena River integrates biogeochemical signals seas, which is estimated to be about 4 Tg. Observations sup- from its vast drainage basin, and the integrated signal reaches port the hypothesis of a dominant role for coastal erosion far out over the Arctic Ocean. Transformation of riverine or- (Semiletov, 1999a, b) in East Siberian Arctic Shelf (ESAS) ganic carbon (OC) into mineral carbon, and mineral carbon sedimentation and the dynamics of the carbon/carbonate sys- into the organic form in the Lena River watershed, can be tem. The Lena River is characterized by relatively high con- considered to be quasi-steady-state processes. An increase in centrations of the primary greenhouse gases, dissolved car- Lena discharge exerts opposite effects on total organic (TOC) bon dioxide (CO2) and methane (CH4). During all seasons and total inorganic (TCO2) carbon: TOC concentration in- the river is supersaturated in CO2 compared to the atmo- creases, while TCO2 concentration decreases. Significant sphere, by up to 1.5–2 fold in summer, and 4–5 fold in winter. inter-annual variability in mean values of TCO2, TOC, and This results in a significant CO2 supersaturation in the adja- their sum (total carbon, TC) has been found. This variabil- cent coastal sea. Localized areas of dissolved CH4 along the ity is determined by changes in land hydrology which cause Lena River and in the Lena delta channels may reach 100 nM, differences in the Lena River discharge. There is a negative but the CH4 concentration decreases to 5–20 nM towards the correlation in the Lena River between TC in September and sea, which suggests that riverborne export of CH4 plays but its mean discharge in August; a time shift of about one month a minor role in determining the ESAS CH4 budget in coastal is required for water to travel from Yakutsk to the Laptev Sea. waters. Instead, the seabed appears to be the source that pro- Total carbon entering the sea with the Lena discharge is es- vides most of the CH4 to the Arctic Ocean. timated to be almost 10 Tg C yr−1. The annual Lena River discharge of particulate organic carbon (POC) can be as high as 0.38 Tg (moderate to high estimate). If we instead accept 1 Introduction Lisytsin’s (1994) statement that 85–95 % of total particulate matter (PM) (and POC) precipitates on the marginal “filter”, The Arctic Ocean is surrounded by permafrost which is being then only about 0.03–0.04 Tg of Lena River POC reaches the degraded at an increasing rate under conditions of warming Laptev Sea. The Lena’s POC export would then be two or- which are most pronounced in Siberia and Alaska (ACIA, ders of magnitude less than the annual input of eroded ter- 2004; Richter-Menge et al., 2006). Permafrost thawing ac- restrial carbon onto the shelf of the Laptev and East Siberian celerates both river discharge (Lyon and Destouni, 2010), and carbon losses from soils (Finlay et al., 2006; Freeman et al., 2001; Guo et al., 2007). Siberian freshwater dis- Correspondence to: I. P. Semiletov charge to the Arctic Ocean is expected to increase with in- ([email protected]) creasing temperatures (Savelieva et al., 2000; Semiletov et Published by Copernicus Publications on behalf of the European Geosciences Union. 2408 I. P. Semiletov et al.: Carbon transport by the Lena River al., 2000; Peterson et al., 2002), which in turn may result in Among the GSARs the Lena River is considered to be the greater river export of old terrigenous organic carbon (OC) major source of total OM, which is the sum of dissolved or- that has recently been documented to be fluvially exported ganic carbon (DOC) and particulate organic carbon (POC), to the ocean (Guo et al., 2004; van Dongen et al., 2008; to the Arctic Ocean (Gordeev et al., 1996). Cauwet and Vonk et al., 2010a; Gustafsson et al., 2011). Rivers in- Sidorov (1996) and Lara et al. (1998) estimated the annual tegrate variability in the components of the hydrometeoro- modern Lena River POC discharge as 1.8 Tg (1 Tg = 1012 g), logical regime, including soil condition, permafrost seasonal higher than that of any other GSAR, and the Lena River DOC thaw, and thermokarst development, all the variables that de- discharge as 3.6 Tg, twice as high as that of the Yangtze River termine the atmospheric and ground water supply for rivers – the largest among Asian rivers. Boucsein et al. (2000) ar- and the chemical weathering in their watersheds. Thus, arc- gue that a significant change in composition of sediment OM tic rivers form an important link between the land and ocean (an increase of freshwater alginite and immature plant ma- carbon pools. In addition to serving as natural large-scale in- terial) on the Laptev Sea continental slope at the beginning tegrators of carbon-related processes occurring in their exten- of the Holocene was due to increased Lena River discharge. sive drainage basins, the coastal export by the Great Siberian Alternatively, Bauch et al. (2001) believe that the increased Arctic rivers (GSARs: Yenisey, Lena, Ob, Kolyma, and Indi- Holocene deposition of OM in the Laptev Sea was mainly the girka) of carbon and nutrients plays a critical role in the bio- result of coastal erosion due to sea level transgression. There- geochemical regime of the Arctic Ocean. Evasion of carbon fore, it is important to study the role of the Lena River and dioxide (CO2) and methane (CH4) from river streams can coastal erosion in different summer months when the major significantly change the regional or even the global carbon water and solid discharges occur. cycle (Kling et al., 1991; Richey et al., 2002; Bastviken et al., Summer runoff from land, dominated by input from 2011). These authors cautioned that direct measurements of organic-rich soils, ice-complexes, and the mires of north- land-atmosphere CO2 (and CH4) exchange that ignore water- ern Asia, is an important source of carbon and nutrients to borne fluxes might significantly overestimate terrestrial car- the shelf seas. Recent large-scale studies of terrestrial car- bon accumulation. A hypothesized climate-change-driven bon in the East Siberian Arctic Shelf (ESAS) water column increase in terrestrial OC inputs to the Arctic Ocean through has documented significant degradation of the terrOM (e.g., permafrost thawing, increased river runoff, and accelerated Semiletov et al., 2007; Anderson et al., 2009, 2011; Alling coastal erosion could dramatically alter carbon budgets and et al., 2010; Vonk et al., 2010a; Sanchez-Garc´ ´ıa et al., 2011). biogeochemical cycles. While the fate and transport pro- Further, surface water from the Laptev Sea shelf, rich in dis- cesses of terrestrial OC across the Arctic land/ocean margin solved OM, follows Gakkel Ridge towards Fram Strait (An- and consequent gas exchange are largely unknown, under- derson et al., 1998), possibly determining bacterial produc- standing them is critical to our understanding of environmen- tion over the Amerasian shelf and the Arctic Basin (Wheeler tal change on a time scale of human concern. et al., 1996; Opsahl et al., 1999). The Lena River is also Documented significant increases in the annual amplitude considered to be the main sediment source for the Laptev of GSAR discharges and air temperatures in their watersheds Sea (Alabyan et al., 1995; Rachold et al., 2004), although over the past 30 yr (Savelieva et al., 2000; Semiletov et al., the amount of suspended sediment delivered to the sea is still 2000) have coincided with an increase in the amplitude of the under some debate (Charkin et al., 2011). Note that most seasonal atmospheric CO2 and CH4 cycles in the north (Con- of the Lena River solid discharge estimates are based on the way et al., 1994; IPCC, 2001), indicating a general increase data obtained near the Kyusur hydrometeorological station in climatic variability. Therefore, a positive feedback loop which is located upstream from the Lena Delta. Thus, actual could operate between the emission of CO2 and CH4 from sedimentation in the Lena Delta channels and foredelta has northern ecosystems and changes in the atmospheric circula- yet to be studied. tion and land hydrology, potentially resulting in greater flu- Hydrometeorological analyses explaining the significant vial export of terrestrial organic matter (terrOM). Changes role of the Lena River-Laptev Sea system in the arc- in the export of terrestrial carbon will certainly affect bio- tic freshwater budget can be found in Nikiforov and geochemical cycling and carbon balance in the ESAS seas Shpaikher (1980), Zakharov (1996), and Semiletov et (Alling et al., 2010; Charkin et al., 2011; Romankevich al. (2000). We view the Lena River as the seminal Siberian and Vetrov, 2001; Sanchez-Garc´ ´ıa et al., 2011; Semiletov et river because changes in Lena River hydrology cause sig- al., 2005; Stein and Macdonald, 2004; van Dongen et al., nificant changes in ice and freshwater input to the Transpo- 2008).
Load more

Recommended publications
  • Abstract Book.Pdf
    Executive Committee Motoyuki Suzuki, International EMECS Center, Japan Toshizo Ido, International EMECS Center, Governor of Hyogo Prefecture, Japan Leonid Zhindarev, Working Group “Sea Coasts” RAS, Russia Valery Mikheev, Russian State Hydrometeorological University, Russia Masataka Watanabe, International EMECS Center, Japan Robert Nigmatullin, P.P. Shirshov Institute of Oceanology RAS, Russia Oleg Petrov, A.P. Karpinsky Russian Geological Research Institute, Russia Scientific Programme Committee Ruben Kosyan, Southern Branch of the P.P. Shirshov Institute of Oceanology RAS, Russia – Chair Masataka Watanabe, Chuo University, International EMECS Center, Japan – Co-Chair Petr Brovko, Far Eastern Federal University, Russia Zhongyuan Chen, East China Normal University, China Jean-Paul Ducrotoy, Institute of Estuarine and Coastal Studies, University of Hull, France George Gogoberidze, Russian State Hydrometeorological University, Russia Sergey Dobrolyubov, Academic Council of the Russian Geographical Society, M.V. Lomonosov Moscow State University, Russia Evgeny Ignatov, M.V. Lomonosov Moscow State University, Russia Nikolay Kasimov, Russian Geographical Society, Technological platform “Technologies for Sustainable Ecological Development” Igor Leontyev, P.P. Shirshov Institute of Oceanology RAS, Russia Svetlana Lukyanova, M.V. Lomonosov Moscow State University, Russia Menasveta Piamsak, Royal Institute, Thailand Erdal Ozhan, MEDCOAST Foundation, Turkey Daria Ryabchuk, A.P. Karpinsky Russian Geological Research Institute, Russia Mikhail Spiridonov,
    [Show full text]
  • Consensus Statement
    Arctic Climate Forum Consensus Statement 2020-2021 Arctic Winter Seasonal Climate Outlook (along with a summary of 2020 Arctic Summer Season) CONTEXT Arctic temperatures continue to warm at more than twice the global mean. Annual surface air temperatures over the last 5 years (2016–2020) in the Arctic (60°–85°N) have been the highest in the time series of observations for 1936-20201. Though the extent of winter sea-ice approached the median of the last 40 years, both the extent and the volume of Arctic sea-ice present in September 2020 were the second lowest since 1979 (with 2012 holding minimum records)2. To support Arctic decision makers in this changing climate, the recently established Arctic Climate Forum (ACF) convened by the Arctic Regional Climate Centre Network (ArcRCC-Network) under the auspices of the World Meteorological Organization (WMO) provides consensus climate outlook statements in May prior to summer thawing and sea-ice break-up, and in October before the winter freezing and the return of sea-ice. The role of the ArcRCC-Network is to foster collaborative regional climate services amongst Arctic meteorological and ice services to synthesize observations, historical trends, forecast models and fill gaps with regional expertise to produce consensus climate statements. These statements include a review of the major climate features of the previous season, and outlooks for the upcoming season for temperature, precipitation and sea-ice. The elements of the consensus statements are presented and discussed at the Arctic Climate Forum (ACF) sessions with both providers and users of climate information in the Arctic twice a year in May and October, the later typically held online.
    [Show full text]
  • Recent Declines in Warming and Vegetation Greening Trends Over Pan-Arctic Tundra
    Remote Sens. 2013, 5, 4229-4254; doi:10.3390/rs5094229 OPEN ACCESS Remote Sensing ISSN 2072-4292 www.mdpi.com/journal/remotesensing Article Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra Uma S. Bhatt 1,*, Donald A. Walker 2, Martha K. Raynolds 2, Peter A. Bieniek 1,3, Howard E. Epstein 4, Josefino C. Comiso 5, Jorge E. Pinzon 6, Compton J. Tucker 6 and Igor V. Polyakov 3 1 Geophysical Institute, Department of Atmospheric Sciences, College of Natural Science and Mathematics, University of Alaska Fairbanks, 903 Koyukuk Dr., Fairbanks, AK 99775, USA; E-Mail: [email protected] 2 Institute of Arctic Biology, Department of Biology and Wildlife, College of Natural Science and Mathematics, University of Alaska, Fairbanks, P.O. Box 757000, Fairbanks, AK 99775, USA; E-Mails: [email protected] (D.A.W.); [email protected] (M.K.R.) 3 International Arctic Research Center, Department of Atmospheric Sciences, College of Natural Science and Mathematics, 930 Koyukuk Dr., Fairbanks, AK 99775, USA; E-Mail: [email protected] 4 Department of Environmental Sciences, University of Virginia, 291 McCormick Rd., Charlottesville, VA 22904, USA; E-Mail: [email protected] 5 Cryospheric Sciences Branch, NASA Goddard Space Flight Center, Code 614.1, Greenbelt, MD 20771, USA; E-Mail: [email protected] 6 Biospheric Science Branch, NASA Goddard Space Flight Center, Code 614.1, Greenbelt, MD 20771, USA; E-Mails: [email protected] (J.E.P.); [email protected] (C.J.T.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +1-907-474-2662; Fax: +1-907-474-2473.
    [Show full text]
  • Article of a Given In- with Postdepositional Erosion
    Earth Surf. Dynam., 8, 769–787, 2020 https://doi.org/10.5194/esurf-8-769-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Timing of exotic, far-traveled boulder emplacement and paleo-outburst flooding in the central Himalayas Marius L. Huber1,a, Maarten Lupker1, Sean F. Gallen2, Marcus Christl3, and Ananta P. Gajurel4 1Geological Institute, Department of Earth Sciences, ETH Zurich, Zurich 8092, Switzerland 2Department of Geosciences, Colorado State University, Fort Collins, Colorado 80523, USA 3Laboratory of Ion Beam Physics (LIP), Department of Physics, ETH Zurich, Zurich 8093, Switzerland 4Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal acurrent address: Université de Lorraine, CNRS, CRPG, 54000 Nancy, France Correspondence: Marius L. Huber ([email protected]) Received: 28 February 2020 – Discussion started: 20 March 2020 Revised: 21 July 2020 – Accepted: 11 August 2020 – Published: 22 September 2020 Abstract. Large boulders, ca. 10 m in diameter or more, commonly linger in Himalayan river channels. In many cases, their lithology is consistent with source areas located more than 10 km upstream, suggesting long trans- port distances. The mechanisms and timing of “exotic” boulder emplacement are poorly constrained, but their presence hints at processes that are relevant for landscape evolution and geohazard assessments in mountainous regions. We surveyed river reaches of the Trishuli and Sunkoshi, two trans-Himalayan rivers in central Nepal, to improve our understanding of the processes responsible for exotic boulder transport and the timing of em- placement. Boulder size and channel hydraulic geometry were used to constrain paleo-flood discharge assuming turbulent, Newtonian fluid flow conditions, and boulder exposure ages were determined using cosmogenic nu- clide exposure dating.
    [Show full text]
  • Sediment Transport to the Laptev Sea-Hydrology and Geochemistry of the Lena River
    Sediment transport to the Laptev Sea-hydrology and geochemistry of the Lena River V. RACHOLD, A. ALABYAN, H.-W. HUBBERTEN, V. N. KOROTAEV and A. A, ZAITSEV Rachold, V., Alabyan, A., Hubberten, H.-W., Korotaev, V. N. & Zaitsev, A. A. 1996: Sediment transport to the Laptev Sea-hydrology and geochemistry of the Lena River. Polar Research 15(2), 183-196. This study focuses on the fluvial sediment input to the Laptev Sea and concentrates on the hydrology of the Lena basin and the geochemistry of the suspended particulate material. The paper presents data on annual water discharge, sediment transport and seasonal variations of sediment transport. The data are based on daily measurements of hydrometeorological stations and additional analyses of the SPM concentrations carried out during expeditions from 1975 to 1981. Samples of the SPM collected during an expedition in 1994 were analysed for major, trace, and rare earth elements by ICP-OES and ICP-MS. Approximately 700 h3freshwater and 27 x lo6 tons of sediment per year are supplied to the Laptev Sea by Siberian rivers, mainly by the Lena River. Due to the climatic situation of the drainage area, almost the entire material is transported between June and September. However, only a minor part of the sediments transported by the Lena River enters the Laptev Sea shelf through the main channels of the delta, while the rest is dispersed within the network of the Lena Delta. Because the Lena River drains a large basin of 2.5 x lo6 km2,the chemical composition of the SPM shows a very uniform composition.
    [Show full text]
  • 34. Information Sheet on Ramsar Wetlands Categories Approved by Recommendation 4.7 of the Conference of the Contracting Parties
    34. Information Sheet on Ramsar Wetlands Categories approved by Recommendation 4.7 of the Conference of the Contracting Parties. NOTE: It is important that you read the accompanying Explanatory Note and Guidelines document before completing this form. 1. Date this sheet was FOR OFFICE USE ONLY. completed/updated: DD MM YY September 1997 Designation date Site Reference Number 2. Country: Russian Federation 3. Name of wetland: Brekhovsky Islands in the Yenisei estuary 4. Geographical coordinates: 70°30'N, 82°45'E 5. Altitude: floodplain and islands: < 10 m; 6. Area: c. 1,400,000 ha bedrock coast: up to 118 m a.s.l. 7. Overview: An estuarine wetland complex, incorporating a network of rivers, streams, channels and lakes, as well as islands, floodplains and terraces covered with tundra vegetation. The area is internationally important for breeding, staging and moulting birds, in particular for red-breasted goose Branta ruficollis. 8. Wetland Type (please circle the applicable codes for wetland types as listed in Annex I of the Explanatory Note and Guidelines document.) marine-coastal: A • B • C • D • E • F • G • H • I • J • K inland: L • M • N • O • P • Q • R • Sp • Ss • Tp • Ts U • Va • Vt • W • Xf • Xp • Y • Zg • Zk man-made: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 Please now rank these wetland types by listing them from the most to the least dominant: L,Ts,U,W,O,M . 9. Ramsar Criteria: (please circle the applicable criteria; see point 12, next page.) 1a • 1b • 1c • 1d │ 2a • 2b • 2c • 2d │ 3a • 3b • 3c │ 4a • 4b Please specify the most significant criterion applicable to the site: 1c 10.
    [Show full text]
  • Late Quaternary Environment of Central Yakutia (NE' Siberia
    Late Quaternary environment of Central Yakutia (NE’ Siberia): Signals in frozen ground and terrestrial sediments Spätquartäre Umweltentwicklung in Zentral-Jakutien (NO-Sibirien): Hinweise aus Permafrost und terrestrischen Sedimentarchiven Steffen Popp Steffen Popp Alfred-Wegener-Institut für Polar- und Meeresforschung Forschungsstelle Potsdam Telegrafenberg A43 D-14473 Potsdam Diese Arbeit ist die leicht veränderte Fassung einer Dissertation, die im März 2006 dem Fachbereich Geowissenschaften der Universität Potsdam vorgelegt wurde. 1. Introduction Contents Contents..............................................................................................................................i Abstract............................................................................................................................ iii Zusammenfassung ............................................................................................................iv List of Figures...................................................................................................................vi List of Tables.................................................................................................................. vii Acknowledgements ........................................................................................................ vii 1. Introduction ...............................................................................................................1 2. Regional Setting and Climate...................................................................................4
    [Show full text]
  • Natural Variability of the Arctic Ocean Sea Ice During the Present Interglacial
    Natural variability of the Arctic Ocean sea ice during the present interglacial Anne de Vernala,1, Claude Hillaire-Marcela, Cynthia Le Duca, Philippe Robergea, Camille Bricea, Jens Matthiessenb, Robert F. Spielhagenc, and Ruediger Steinb,d aGeotop-Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada; bGeosciences/Marine Geology, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Germany; cOcean Circulation and Climate Dynamics Division, GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany; and dMARUM Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, 28334 Bremen, Germany Edited by Thomas M. Cronin, U.S. Geological Survey, Reston, VA, and accepted by Editorial Board Member Jean Jouzel August 26, 2020 (received for review May 6, 2020) The impact of the ongoing anthropogenic warming on the Arctic such an extrapolation. Moreover, the past 1,400 y only encom- Ocean sea ice is ascertained and closely monitored. However, its pass a small fraction of the climate variations that occurred long-term fate remains an open question as its natural variability during the Cenozoic (7, 8), even during the present interglacial, on centennial to millennial timescales is not well documented. i.e., the Holocene (9), which began ∼11,700 y ago. To assess Here, we use marine sedimentary records to reconstruct Arctic Arctic sea-ice instabilities further back in time, the analyses of sea-ice fluctuations. Cores collected along the Lomonosov Ridge sedimentary archives is required but represents a challenge (10, that extends across the Arctic Ocean from northern Greenland to 11). Suitable sedimentary sequences with a reliable chronology the Laptev Sea were radiocarbon dated and analyzed for their and biogenic content allowing oceanographical reconstructions micropaleontological and palynological contents, both bearing in- can be recovered from Arctic Ocean shelves, but they rarely formation on the past sea-ice cover.
    [Show full text]
  • Molecular Evidence for Pervasive Riverine Export of Soil Organic Matter from the Central Himalaya
    EGU2020-9017 https://doi.org/10.5194/egusphere-egu2020-9017 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Molecular evidence for pervasive riverine export of soil organic matter from the Central Himalaya Lena Märki1, Maarten Lupker1, Ananta Gajurel2, Hannah Gies1, Negar Haghipour1,3, Sean Gallen4, Christian France-Lanord5, Jérôme Lavé5, and Timothy Eglinton1 1ETH Zurich, Geological Institute, Department of Earth Sciences, Zurich, Switzerland ([email protected]) 2Tribhuvan University, Department of Geology, Kathmandu, Nepal 3ETH Zurich, Ion Beam Physics, Zurich, Switzerland 4Colorado State University, Department of Geosciences, Fort Collins, USA 5CNRS – Université de Lorraine, Centre de Recherches Pétrographiques et Géochimiques, Vandœuvre-lès-Nancy, France Soil erosion in high mountain ranges plays an important role in redistributing soil organic carbon across landscapes and may influence the global climate on different timescales [1, 2]. Here, we investigate the dynamics of soil organic matter export in the steep mountain belt of the Himalaya by tracing the provenance of soil-derived lipids in riverine sediments from nested catchments with areas ranging from 370 to 57700 km2. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a suite of lipids that occur ubiquitously in soils [3, 4]. Their isomer distribution depends on environmental parameters such as the mean annual temperature of the local environment [3]. In this study, we explore the use of brGDGT distributions as a proxy for the altitudinal provenance of soil organic matter in riverine sediments of the Central Himalaya of Nepal. BrGDGT distributions in soils collected along an altitudinal profile, spanning elevations from 200 to 4450 m asl, yield a robust calibration of soil signatures as a function of elevation.
    [Show full text]
  • Geochemistry of Surficial and Ice-Rafted Sediments from The
    Estuarine, Coastal and Shelf Science (1999) 49, 45–59 Article No. ecss.1999.0485, available online at http://www.idealibrary.com on Geochemistry of Surficial and Ice-rafted Sediments from the Laptev Sea (Siberia) J. A. Ho¨lemanna, M. Schirmacherb, H. Kassensa and A. Prangeb aGEOMAR, Forschungszentrum fu¨r marine Geowissenschaften, Wischhofstr. 1–3, 24148 Kiel, Germany bGKSS, Forschungszentrum Geesthacht GmbH, Max-Planck-Str., 21502 Geesthacht, Germany Received 20 June 1997 and accepted in revised form 19 February 1999 The Laptev Sea, as a part of the world’s widest continental shelves surrounding the Arctic Ocean, is a key area for understanding the land–ocean interaction in high latitude regions. With a yearly freshwater input of 511 km3, the Lena River—one of the eight major world rivers—has an influencing control over the environment of this Arctic marginal sea, which is ice-covered during most of the year. In this paper, the first measurements are presented of the major and trace element distribution within the <20 ìm grain size fraction of surficial sediments and of particulate matter in new and young ice from the Laptev Sea (Siberian Arctic). The concentration and distribution of major and trace elements have been determined in 51 surficial sediment samples covering the whole Laptev Sea shelf south of the 50 m isobath. Thirty-one samples of particulate matter in newly formed ice were taken during the freeze-up period in 1995. Median concentration levels of heavy metals in surficial sediments (Ni (46 ìgg"1), Cu (26 ìgg"1), Zn (111 ìgg"1) and Pb (21 ìgg"1) are within the concentration range of marine unpolluted sediments.
    [Show full text]
  • 1 Lena Kolarska-Bobińska Completed Transformation: Integration Into the European Union for the Countries of Central and Eastern
    Lena Kolarska-Bobiska Completed Transformation: integration into the European Union For the countries of Central and Eastern Europe full integration with the European Union will constitute the crowning moment of their as yet unfinished economic and political transformation. The EU integration process will also become a crucial driving force for changes of the social structure, institutions and group interests whose new framework have been emerging since the fall of the Communist system. This fact that integration into the EU is the final stage of transformation of the candidate countries and not merely a process of adapting to external conditions makes the present enlargement quite different to anything experienced before. When Sweden or Austria sought to join the Western European community their societies had a stable social structure and well-formed and effectively functioning democratic and financial institutions. In their case integration meant no more than adaptation of well developed and stable social systems to some new norms and circumstances and not as in the former Communist run countries the continuation of radical political and social changes. Poland, the Czech Republic and Hungary are countries were a new social order and social structures are emerging. As integration is a driving force for change and is dictating its direction it will have an basic impact on the final character of those societies. In this paper I would focus on the social changes which Poland faces as a result of the integration process and their impact on the evolution of attitudes to membership in the European Union. THE FIRST STAGE OF TRANSFORMATION: FROM ANOMY TO ADAPTATION (1989-1997) The changes in Poland followed a slightly different pattern from those in Hungary or the Czech Republic.
    [Show full text]
  • The Contribution of Shore Thermoabrasion to the Laptev Sea Sediment Balance
    THE CONTRIBUTION OF SHORE THERMOABRASION TO THE LAPTEV SEA SEDIMENT BALANCE F.E. Are Petersburg State University of Means of Communications, Moskovsky av. 9, St.-Petersburg, 190031, Russia e-mail: [email protected] Abstract A schematic map of Laptev Sea shore dynamics is compiled for the first time, using available published data. It shows the distribution of thermoabrasion shores, mean long-term shore retreat rates, and areas of seabed ero- sion and accretion. The amount of sediment released to the sea from the 85 km Anabar-Olenyok section of the coast is calculated, as an example, at 3.4 Mt/year. These results are compared with published data on sediment transport of rivers running into the Laptev Sea. Estimates of the Lena River discharge range from 12 to 21 Mt/year, of which only 2.1 to 3.5 Mt may reach the sea. The analysis shows that the input of thermoabrasion at mean shoreline retreat rates of 0.7 to 0.9 m/year is at least of the same order as the river input and may great- ly exceed it. Introduction ble to determine the input from shore thermoabrasion offshore more accurately. Thousands of kilometres of Arctic sea coast retreat at rates 2-6 m/year under the action of thermoabrasion1 Maps of shore dynamics are needed to solve this (Are, 1985; Barnes et al., 1991). Tens of square kilome- problem and others related to climate change impacts. tres of Arctic land therefore are consumed by the sea Such maps have been compiled for about 650 km of every year.
    [Show full text]