Department Surface Waters - Research and Management

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array(9 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=18193, pid=124)
      originalId => protected18193 (integer)
      authors => protected'Sommer, T.; Schmid, M.; Wüest, A.' (49 chars)
      title => protected'The role of double diffusion for the heat and salt balance in Lake Kivu' (71 chars)
      journal => protected'Limnology and Oceanography' (26 chars)
      year => protected2019 (integer)
      volume => protected64 (integer)
      issue => protected'2' (1 chars)
      startpage => protected'650' (3 chars)
      otherpage => protected'660' (3 chars)
      categories => protected'' (0 chars)
      description => protected'Double diffusion in lakes and oceans can transform vertical gradients into s
         taircases of convectively mixed layers separated by thin stable interfaces. 
         
         
         5 microstructure profiles (225 measured in Rwanda and 90 in the DRC) to shed
          light on the heat and salt balances of Lake Kivu. Comparing profiles from 2
         011 and 2015 reveals warming of 8.6 mK yr<sup>−1</sup> below 80 m depth 
         and negligible changes in salinity. The double‐diffusive layering is coher
         ent over horizontal distances of 20–30 km and remained unchanged between
          2011 and 2015, indicating little variability. The mean estimated dissipatio
         n within mixed layers is 1.5 × 10<sup>−10</sup> W kg<sup>−1</sup>
         . If unshaped Batchelor microstructure spectra are interpreted as nonturbule
         
         
         hich agrees with the molecular heat flux through the adjacent stable interfa
         ces. Using estimates of upwelling, temporal changes of temperature and salt,
          and vertical double‐diffusive fluxes, we established heat and salt balanc
         es, which require lateral heat and salt inputs. For salt, lateral input of f
         reshwater at the main gradients balances upwelling. For temperature, however
         , the divergence of the vertical double‐diffusive fluxes can only be balan
         ced by horizontal inputs supplying cool water above and warm water below the
          main gradients. This suggests that lateral inputs of water at various depth
         s are the main drivers for this unique double‐diffusive phenomenon in Lake
          Kivu.' (1754 chars)
      serialnumber => protected'0024-3590' (9 chars)
      doi => protected'10.1002/lno.11066' (17 chars)
      uid => protected18193 (integer)
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      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7805, pid=124)
      originalId => protected7805 (integer)
      authors => protected'Scheifele,&nbsp;B.; Pawlowicz,&nbsp;R.; Sommer,&nbsp;T.; Wüest,&nbsp;A.' (72 chars)
      title => protected'Double diffusion in saline Powell Lake, British Columbia' (56 chars)
      journal => protected'Journal of Physical Oceanography' (32 chars)
      year => protected2014 (integer)
      volume => protected44 (integer)
      issue => protected'11' (2 chars)
      startpage => protected'2893' (4 chars)
      otherpage => protected'2908' (4 chars)
      categories => protected'' (0 chars)
      description => protected'Powell Lake contains a deep layer of relic seawater separated from the ocean
          since the last ice age. Permanently stratified and geothermally heated from
          below, this deep layer is an isolated geophysical domain suitable for study
         ing double-diffusive convection. High-resolution CTD and microstructure meas
         urements show several double-diffusive staircases (<I>R</I><I><SUB>ρ</SUB><
         /I> = 1.6 to 6) in the deep water, separated vertically by smooth high-gradi
         ent regions with much larger density ratios. The lowest staircase contains s
         teps that are laterally coherent on the basin scale and have a well-defined 
         vertical structure. On average, temperature steps in this staircase are 4 mK
         , salinity steps are 2 mg kg<SUP>−1</SUP>, and mixed layer heights are 70 
         cm. The CTD is capable of measuring bulk characteristics of the staircase in
          both temperature and salinity. Microstructure measurements are limited to t
         emperature alone, but resolve the maximum temperature gradients in the cente
         r of selected laminar interfaces. Two different algorithms for characterizin
         g the staircase are compared. Consistent estimates of the steady-state heat 
         flux (27 mW m<SUP>−2</SUP>) are obtained from measurements above and below
          the staircase, as well as from microstructure measurements in the center of
          smooth interfaces. Estimates obtained from bulk interface gradients underes
         timate the steady-state flux by nearly a factor of 2. The mean flux calculat
         ed using a standard 4/3 flux law parameterization agrees well with the indep
         endent estimates, but inconsistencies between the parameterization and the o
         bservations remain. These inconsistencies are examined by comparing the unde
         rlying scaling relationship to the measurements.' (1720 chars)
      serialnumber => protected'0022-3670' (9 chars)
      doi => protected'10.1175/JPO-D-14-0070.1' (23 chars)
      uid => protected7805 (integer)
      _localizedUid => protected7805 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7805 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7724, pid=124)
      originalId => protected7724 (integer)
      authors => protected'Sommer,&nbsp;T.; Carpenter,&nbsp;J.&nbsp;R.; Wüest,&nbsp;A.' (60 chars)
      title => protected'Double-diffusive interfaces in Lake Kivu reproduced by direct numerical simu
         lations' (83 chars)
      journal => protected'Geophysical Research Letters' (28 chars)
      year => protected2014 (integer)
      volume => protected41 (integer)
      issue => protected'14' (2 chars)
      startpage => protected'5114' (4 chars)
      otherpage => protected'5121' (4 chars)
      categories => protected'' (0 chars)
      description => protected'Double diffusion transforms uniform background gradients of temperature and 
         salinity into “staircases” of homogeneous mixed layers that are separate
         d by high-gradient interfaces. Direct numerical simulations (DNS) and micros
         tructure measurements are two independent methods of estimating double-diffu
         sive fluxes. By performing DNS under similar conditions as found in our meas
         urements in Lake Kivu, we are able to compare results from both methods for 
         the first time. We find that (i) the DNS reproduces the measured interface t
         hicknesses of in situ microstructure profiles, (ii) molecular heat fluxes th
         rough interfaces capture the total vertical heat fluxes for density ratios l
         arger than three, and (iii) the commonly used heat flux parameterization und
         erestimates the total fluxes by a factor of 1.3 to 2.2.' (815 chars)
      serialnumber => protected'0094-8276' (9 chars)
      doi => protected'10.1002/2014GL060716' (20 chars)
      uid => protected7724 (integer)
      _localizedUid => protected7724 (integer)modified
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      _versionedUid => protected7724 (integer)modified
      pid => protected124 (integer)
   3 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7496, pid=124)
      originalId => protected7496 (integer)
      authors => protected'Sommer,&nbsp;T.; Carpenter,&nbsp;J.&nbsp;R.; Schmid,&nbsp;M.; Lueck,&nbsp;R.
         &nbsp;G.; Schurter,&nbsp;M.; Wüest,&nbsp;A.' (120 chars)
      title => protected'Interface structure and flux laws in a natural double-diffusive layering' (72 chars)
      journal => protected'Journal of Geophysical Research: Oceans' (39 chars)
      year => protected2013 (integer)
      volume => protected118 (integer)
      issue => protected'11' (2 chars)
      startpage => protected'6092' (4 chars)
      otherpage => protected'6106' (4 chars)
      categories => protected'' (0 chars)
      description => protected'The diffusive regime of double-diffusive convection generates staircases con
         sisting of thin high-gradient interfaces sandwiched between convectively mix
         ed layers. Simultaneous microstructure measurements of both temperature and 
         conductivity from the staircases in Lake Kivu are used to test flux laws and
          theoretical models for double diffusion. Density ratios in Lake Kivu are be
         tween one and ten and mixed layer thicknesses on average 0.7 m. The larger i
         nterface thickness of temperature (average 9 cm) compared to dissolved subst
         ances (6 cm) confirms the boundary-layer structure of the interface. Our obs
         ervations suggest that the boundary-layer break-off cannot be characterized 
         by a single critical boundary-layer Rayleigh number, but occurs within a ran
         ge of O(10<sup>2</sup>) to O(10<sup>4</sup>). Heat flux parameterizations wh
         ich assume that the Nusselt number follows a power law increase with the Ray
         leigh number Ra are tested for their exponent <em>η</em>. In contrast to th
         e standard estimate <em>η</em> = 1/3, we found <em>η</em> = 0.20 ± 0.03 f
         or density ratios between two and six. Therefore, we suggest a correction of
          heat flux estimates which are based on <em>η</em> = 1/3. The magnitude of 
         the correction depends on Ra in the system of interest. For Lake Kivu (avera
         ge heat flux 0.10 W m<sup>−2</sup>) with Ra = O(10<sup>8</sup>), correctio
         ns are marginal. In the Arctic Ocean with Ra = O(10<sup>8</sup>) to O(10<sup
         >12</sup>), however, heat fluxes can be overestimated by a factor of four.' (1518 chars)
      serialnumber => protected'2169-9275' (9 chars)
      doi => protected'10.1002/2013JC009166' (20 chars)
      uid => protected7496 (integer)
      _localizedUid => protected7496 (integer)modified
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      _versionedUid => protected7496 (integer)modified
      pid => protected124 (integer)
   4 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7334, pid=124)
      originalId => protected7334 (integer)
      authors => protected'Sommer,&nbsp;T.; Carpenter,&nbsp;J.&nbsp;R.; Schmid,&nbsp;M.; Lueck,&nbsp;R.
         &nbsp;G.; Wüest,&nbsp;A.' (101 chars)
      title => protected'Revisiting microstructure sensor responses with implications for double-diff
         usive fluxes' (88 chars)
      journal => protected'Journal of Atmospheric and Oceanic Technology' (45 chars)
      year => protected2013 (integer)
      volume => protected30 (integer)
      issue => protected'8' (1 chars)
      startpage => protected'1907' (4 chars)
      otherpage => protected'1923' (4 chars)
      categories => protected'' (0 chars)
      description => protected'Thin high-gradient interfaces that occur naturally within double-diffusive s
         taircases are used to estimate the response characteristics of temperature a
         nd conductivity microstructure sensors. The knowledge of these responses is 
         essential for resolving small-scale turbulence in natural water bodies and f
         or determining double-diffusive fluxes of heat and salt. Here, the authors d
         erive microstructure sensor responses from observed differences in the stati
         stical distributions of interface thicknesses at various profiling speeds in
          Lake Kivu (central Africa). In contrast to the standard approach for determ
         ining sensor responses, this method is independent of any knowledge of the t
         rue in situ temperature and salinity structure. Assuming double-pole frequen
         cy response functions, the time constants for the Sea-Bird Electronics SBE-7
          conductivity sensor and the Rockland Scientific International FP07 thermist
         or are estimated to be 2.2 and 10 ms, respectively. In contrast to previous 
         assumptions, the frequency response for the SBE-7 is found to be substantial
          and dominates the wavenumber response for profiling speeds larger than 0.19
          m s<SUP>−1</SUP>.' (1160 chars)
      serialnumber => protected'0739-0572' (9 chars)
      doi => protected'10.1175/JTECH-D-12-00272.1' (26 chars)
      uid => protected7334 (integer)
      _localizedUid => protected7334 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7334 (integer)modified
      pid => protected124 (integer)
   5 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7127, pid=124)
      originalId => protected7127 (integer)
      authors => protected'Carpenter,&nbsp;J.&nbsp;R.; Sommer,&nbsp;T.; Wüest,&nbsp;A.' (60 chars)
      title => protected'Simulations of a double-diffusive interface in the diffusive convection regi
         me' (78 chars)
      journal => protected'Journal of Fluid Mechanics' (26 chars)
      year => protected2012 (integer)
      volume => protected711 (integer)
      issue => protected'' (0 chars)
      startpage => protected'411' (3 chars)
      otherpage => protected'436' (3 chars)
      categories => protected'double diffusive convection; ocean processes; stratified flows' (62 chars)
      description => protected'Three-dimensional direct numerical simulations are performed that give us an
          in-depth account of the evolution and structure of the double-diffusive int
         erface. We examine the diffusive convection regime, which, in the oceanograp
         hically relevant case, consists of relatively cold fresh water above warm sa
         lty water. A 'double-boundary-layer' structure is found in all of the simula
         tions, in which the temperature (<em>T</em>) interface has a greater thickne
         ss than the salinity (<em>S</em>) interface. Therefore, thin gravitationally
          unstable boundary layers are maintained at the edges of the diffusive inter
         face. The <em>TS</em>-interface thickness ratio is found to scale with the d
         iffusivity ratio in a consistent manner once the shear across the boundary l
         ayers is accounted for. The turbulence present in the mixed layers is not ab
         le to penetrate the stable stratification of the interface core, and the <em
         >TS</em>-fluxes through the core are given by their molecular diffusion valu
         es. Interface growth in time is found to be determined by molecular diffusio
         n of the <em>S</em>-interface, in agreement with a previous theory. The stab
         ility of the boundary layers is also considered, where we find boundary laye
         r Rayleigh numbers that are an order of magnitude lower than previously assu
         med.' (1296 chars)
      serialnumber => protected'0022-1120' (9 chars)
      doi => protected'10.1017/jfm.2012.399' (20 chars)
      uid => protected7127 (integer)
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      pid => protected124 (integer)
   6 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6941, pid=124)
      originalId => protected6941 (integer)
      authors => protected'Carpenter,&nbsp;J.&nbsp;R.; Sommer,&nbsp;T.; Wüest,&nbsp;A.' (60 chars)
      title => protected'Stability of a double-diffusive interface in the diffusive convection regime' (76 chars)
      journal => protected'Journal of Physical Oceanography' (32 chars)
      year => protected2012 (integer)
      volume => protected42 (integer)
      issue => protected'5' (1 chars)
      startpage => protected'840' (3 chars)
      otherpage => protected'854' (3 chars)
      categories => protected'' (0 chars)
      description => protected'In this paper, the authors explore the conditions under which a double-diffu
         sive interface may become unstable. Focus is placed on the case of a cold, f
         reshwater layer above a warm, salty layer [i.e., the diffusive convection (D
         C) regime]. The “diffusive interface” between these layers will develop 
         gravitationally unstable boundary layers due to the more rapid diffusion of 
         heat (the destabilizing component) relative to salt. Previous studies have a
         ssumed that a purely convective-type instability of these boundary layers is
          what drives convection in this system and that this may be parameterized by
          a boundary layer Rayleigh number. The authors test this theory by conductin
         g both a linear stability analysis and direct numerical simulations of a dif
         fusive interface. Their linear stability analysis reveals that the transitio
         n to instability always occurs as an oscillating diffusive convection mode a
         nd at boundary layer Rayleigh numbers much smaller than previously thought. 
         However, these findings are based on making a quasi-steady assumption for th
         e growth of the interfaces by molecular diffusion. When diffusing interfaces
          are modeled (using direct numerical simulations), the authors observe that 
         the time dependence is significant in determining the instability of the bou
         ndary layers and that the breakdown is due to a purely convective-type insta
         bility. Their findings therefore demonstrate that the relevant instability i
         n a DC staircase is purely convective.' (1482 chars)
      serialnumber => protected'0022-3670' (9 chars)
      doi => protected'10.1175/JPO-D-11-0118.1' (23 chars)
      uid => protected6941 (integer)
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      _versionedUid => protected6941 (integer)modified
      pid => protected124 (integer)
   7 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=11600, pid=124)
      originalId => protected11600 (integer)
      authors => protected'Wüest,&nbsp;A.; Sommer,&nbsp;T.; Schmid,&nbsp;M.; Carpenter,&nbsp;J.&nbsp;R
         .' (77 chars)
      title => protected'Diffusive-type of double diffusion in lakes - a review' (54 chars)
      journal => protected'In: Rodi,&nbsp;W.; Uhlmann,&nbsp;M. (Eds.), Environmental fluid mechanics. M
         emorial volume in honour of Prof. Gerhard H. Jirka' (126 chars)
      year => protected2012 (integer)
      volume => protected0 (integer)
      issue => protected'' (0 chars)
      startpage => protected'271' (3 chars)
      otherpage => protected'284' (3 chars)
      categories => protected'' (0 chars)
      description => protected'This chapter is a contribution in honour of Gerhard H Jirka, who has been fa
         scinated by the amazing variety of small-scale structures that nature surpri
         ses us with, particularly in stratified natural waters. Here, we focus on th
         e diffusive regime of double-diffusive convection that occasionally occurs i
         n lakes. Preconditions are a permanent stratification by dissolved constitue
         nts - such as salinity and carbon-dioxide – and convective forcing by deep
          sources of heat. After setting the stage for double diffusion to occur, pos
         sible genesis processes of the diffusive regime are reviewed by explaining s
         pecific examples of this unusual stratification such as (i) the flushing of 
         fossil seawater by freshwater, (ii) the solar-pond phenomenon in ice-covered
          lakes in Antarctica, and (iii) the deep release of salt and gases in volcan
         ic regions. In particular, the two most prominent examples of natural waters
          in which double diffusion occurs, Lakes Nyos and Kivu, are reviewed in more
          detail. The generation and evolution of staircase layering are discussed in
          relation to experiences gained from laboratory experiments, DNS modelling, 
         and analysis of data from natural waters.' (1181 chars)
      serialnumber => protected'' (0 chars)
      doi => protected'10.1201/b12283-18' (17 chars)
      uid => protected11600 (integer)
      _localizedUid => protected11600 (integer)modified
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      _versionedUid => protected11600 (integer)modified
      pid => protected124 (integer)
   8 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6201, pid=124)
      originalId => protected6201 (integer)
      authors => protected'Schmid,&nbsp;M.; Busbridge,&nbsp;M.; Wüest,&nbsp;A.' (52 chars)
      title => protected'Double-diffusive convection in Lake Kivu' (40 chars)
      journal => protected'Limnology and Oceanography' (26 chars)
      year => protected2010 (integer)
      volume => protected55 (integer)
      issue => protected'1' (1 chars)
      startpage => protected'225' (3 chars)
      otherpage => protected'238' (3 chars)
      categories => protected'' (0 chars)
      description => protected'Double-diffusive staircases with a total of 230–350 mixed layers and sharp
          interfaces were observed in nine microstructure temperature profiles measur
         ed during February 2004 in Lake Kivu. The presence of these staircases at de
         pths &gt; 120 m indicates that diapycnal turbulent mixing is weak and vertic
         al diffusive transport is dominated by double diffusion. Contrary to previou
         sly investigated natural or laboratory double-diffusive systems, the dissolv
         ed gases CO<sub>2</sub> and CH<sub>4</sub> contribute significantly to the d
         ensity stratification, thereby influencing the formation and the structure o
         f the staircases. The density ratio (i.e., the ratio of the stabilizing effe
         ct of dissolved substances to the destabilizing effect of temperature) range
         s between 2.0 and 4.5 in large sections of the deep waters, implying a high 
         susceptibility to the formation of staircases. The mixed layers (average thi
         ckness 0.48 m) are shown to be in a state of active convection. The average 
         thickness of the interfaces (0.18 m) is surprisingly constant and independen
         t of the large-scale stratification. The vertical heat fluxes correlate well
          with the temperature steps across the interfaces. Lake Kivu receives inflow
         s from subaquatic springs at several depths that maintain the large-scale st
         ructure of the density stratification and disturb the staircases. In compari
         son to earlier observations from 1972, the double-diffusive heat fluxes appe
         ar to have been reduced, leading to a heat accumulation in the deep waters. 
         Conversely, the strengthening of the main chemocline indicates an increased 
         discharge of the subaquatic springs that could be responsible for recent cha
         nges in the nutrient cycling and methane production in the lake.' (1736 chars)
      serialnumber => protected'0024-3590' (9 chars)
      doi => protected'10.4319/lo.2010.55.1.0225' (25 chars)
      uid => protected6201 (integer)
      _localizedUid => protected6201 (integer)modified
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array(2 items)
   publications => '9181,7768,9054,6912' (19 chars)
   libraryUrl => '' (0 chars)

array(4 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=9181, pid=124)
      originalId => protected9181 (integer)
      authors => protected'Ross, K. A.; Gashugi, E.; Gafasi, A.; Wüest, A.; S
         chmid, M.' (90 chars)
      title => protected'Characterisation of the subaquatic groundwater discharge that maintains the 
         permanent stratification within Lake Kivu; East Africa' (130 chars)
      journal => protected'PLoS One' (8 chars)
      year => protected2015 (integer)
      volume => protected10 (integer)
      issue => protected'3' (1 chars)
      startpage => protected'e0121217 (21 pp.)' (17 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'Warm and cold subaquatic groundwater discharge into Lake Kivu forms the larg
         e-scale density gradients presently observed in the lake. This structure is 
         pertinent to maintaining the stratification that locks the high volume of ga
         ses in the deepwater. Our research presents the first characterisation of th
         ese inflows. Temperature and conductivity profiling was conducted from Janua
         ry 2010 to March 2013 to map the locations of groundwater discharge. Water s
         amples were obtained within the lake at the locations of the greatest temper
         ature anomalies observed from the background lake-profile. The isotopic and 
         chemical signatures of the groundwater were applied to assess how these infl
         
         
         ince its turnover that is speculated to have occurred within the last ~1000 
         yrs. Given a recent salinity increase in the lake constrained to within mont
         hs of seismic activity measured beneath the basin, it is plausible that incr
         eased hydrothermal-groundwater inflows into the deep basin are correlated wi
         th episodic geologic events. These results invalidate the simple two-compone
         nt end-member mixing regime that has been postulated up to now, and indicate
          the importance of monitoring this potentially explosive lake.' (1354 chars)
      serialnumber => protected'' (0 chars)
      doi => protected'10.1371/journal.pone.0121217' (28 chars)
      uid => protected9181 (integer)
      _localizedUid => protected9181 (integer)modified
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      _versionedUid => protected9181 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7768, pid=124)
      originalId => protected7768 (integer)
      authors => protected'Ross, K. A.; Smets, B.; De Batist, M.; Hilbe, M.; S
         chmid, M.; Anselmetti, F. S.' (119 chars)
      title => protected'Lake-level rise in the late Pleistocene and active subaquatic volcanism sinc
         e the Holocene in Lake Kivu, East African Rift' (122 chars)
      journal => protected'Geomorphology' (13 chars)
      year => protected2014 (integer)
      volume => protected221 (integer)
      issue => protected'' (0 chars)
      startpage => protected'274' (3 chars)
      otherpage => protected'285' (3 chars)
      categories => protected'rift lake; lake-level rise; subaquatic volcano; subaquatic lava flow; limnic
          eruption; high-resolution bathymetry' (113 chars)
      description => protected'The history of Lake Kivu is strongly linked to the activity of the Virunga v
         olcanoes. Subaerial and subaquatic volcanoes, in addition to lake-level chan
         ges, shape the subaquatic morphologic and structural features in Lake Kivu's
          Main Basin. Previous studies revealed that volcanic eruptions blocked the f
         ormer outlet of the lake to the north in the late Pleistocene, leading to a 
         substantial rise in the lake level and subsequently the present-day thermoha
         line stratification. Additional studies have speculated that volcanic and se
         ismic activities threaten to trigger a catastrophic release of the large amo
         unt of gases dissolved in the lake. The current study presents a bathymetric
          mapping and seismic profiling survey that covers the volcanically active ar
         ea of the Main Basin at a resolution that is unprecedented for Lake Kivu. Ne
         w geomorphologic features identified on the lake floor can accurately descri
         be related lake-floor processes for the first time. The late Pleistocene low
         stand is observed at 425 m depth, and volcanic cones, tuff rings, and lava 
         flows observed above this level indicate both subaerial and subaquatic volca
         nic activities during the Holocene. The geomorphologic analysis yields new i
         mplications on the geologic processes that have shaped Lake Kivu's basin, an
         d the presence of young volcanic features can be linked to the possibility o
         f a lake overturn.' (1386 chars)
      serialnumber => protected'0169-555X' (9 chars)
      doi => protected'10.1016/j.geomorph.2014.05.010' (30 chars)
      uid => protected7768 (integer)
      _localizedUid => protected7768 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7768 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=9054, pid=124)
      originalId => protected9054 (integer)
      authors => protected'Muvundja, F. A.; Wüest, A.; Isumbisho, M.; Kaningini,&n
         bsp;M. B.; Pasche, N.; Rinta, P.; Schmid, M.' (140 chars)
      title => protected'Modelling Lake Kivu water level variations over the last seven decades' (70 chars)
      journal => protected'Limnologica' (11 chars)
      year => protected2014 (integer)
      volume => protected47 (integer)
      issue => protected'' (0 chars)
      startpage => protected'21' (2 chars)
      otherpage => protected'33' (2 chars)
      categories => protected'East-African lakes; Lake Kivu; hydrological variability; modelling; Ruzizi I
          Hydropower Dam' (91 chars)
      description => protected'This study aimed at analysing the hydrological changes in the Lake Kivu Basi
         n over the last seven decades with focus on the response of the lake water l
         evel to meteorological factors and hydropower dam construction. Historical p
         recipitation and lake water levels were acquired from literature, local agen
         cies and from global databases in order to compile a coherent dataset. The n
         et lake inflow was modelled using a soil water balance model and the water l
         evels were reconstructed using a parsimonious lake water balance model. The 
         soil water balance shows that 370 mm yr<SUP>−1</SUP> (25%) of the precip
         itation in the catchment contributes to the runoff and baseflow whereas 1100
          mm yr<SUP>−1</SUP> (75%) contributes to the evapotranspiration. A revie
         w of the lake water balance resulted in the following estimates of hydrologi
         cal contributions: 55%, 25%, and 20% of the overall inputs from precipitatio
         n, surface inflows, and subaquatic groundwater discharge, respectively. The 
         overall losses were 58% and 42% for lake surface evaporation and outflow dis
         charge, respectively. The hydrological model used indicated a remarkable sen
         sitivity of the lake water levels to hydrometeorological variability up to 1
         977, when the outflow bed was artificially widened.' (1267 chars)
      serialnumber => protected'0075-9511' (9 chars)
      doi => protected'10.1016/j.limno.2014.02.003' (27 chars)
      uid => protected9054 (integer)
      _localizedUid => protected9054 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected9054 (integer)modified
      pid => protected124 (integer)
   3 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6912, pid=124)
      originalId => protected6912 (integer)
      authors => protected'Bhattarai,&nbsp;S.; Ross,&nbsp;K.&nbsp;A.; Schmid,&nbsp;M.; Anselmetti,&nbsp
         ;F.&nbsp;S.; Bürgmann,&nbsp;H.' (107 chars)
      title => protected'Local conditions structure unique archaeal communities in the anoxic sedimen
         ts of meromictic Lake Kivu' (102 chars)
      journal => protected'Microbial Ecology' (17 chars)
      year => protected2012 (integer)
      volume => protected64 (integer)
      issue => protected'2' (1 chars)
      startpage => protected'291' (3 chars)
      otherpage => protected'310' (3 chars)
      categories => protected'' (0 chars)
      description => protected'Meromictic Lake Kivu is renowned for its enormous quantity of methane dissol
         ved in the hypolimnion. The methane is primarily of biological origin, and i
         ts concentration has been increasing in the past half-century. Insight into 
         the origin of methane production in Lake Kivu has become relevant with the r
         ecent commercial extraction of methane from the hypolimnion. This study prov
         ides the first culture-independent approach to identifying the archaeal comm
         unities present in Lake Kivu sediments at the sediment-water interface. Term
         inal restriction fragment length polymorphism analysis suggests considerable
          heterogeneity in the archaeal community composition at varying sample locat
         ions. This diversity reflects changes in the geochemical conditions in the s
         ediment and the overlying water, which are an effect of local groundwater in
         flows. A more in-depth look at the archaeal community composition by clone l
         ibrary analysis revealed diverse phylogenies of <I>Euryarchaeota</I> and <I>
         Crenarachaeota</I>. Many of the sequences in the clone libraries belonged to
          globally distributed archaeal clades such as the rice cluster V and Lake Da
         gow sediment environmental clusters. Several of the determined clades were p
         reviously thought to be rare among freshwater sediment Archaea (e.g., sequen
         ces related to the SAGMEG-1 clade). Surprisingly, there was no observed rela
         tion of clones to known hydrogentrophic methanogens and less than 2 % of clo
         nes were related to acetoclastic methanogens. The local variability, diversi
         ty, and novelty of the archaeal community structure in Lake Kivu should be c
         onsidered when making assumptions on the biogeochemical functioning of its s
         ediments.' (1681 chars)
      serialnumber => protected'0095-3628' (9 chars)
      doi => protected'10.1007/s00248-012-0034-x' (25 chars)
      uid => protected6912 (integer)
      _localizedUid => protected6912 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected6912 (integer)modified
      pid => protected124 (integer)

array(2 items)
   publications => '9054,6670,6493,6097,6113' (24 chars)
   libraryUrl => '' (0 chars)

array(5 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=9054, pid=124)
      originalId => protected9054 (integer)
      authors => protected'Muvundja, F. A.; Wüest, A.; Isumbisho, M.; Kaningini,&n
         bsp;M. B.; Pasche, N.; Rinta, P.; Schmid, M.' (140 chars)
      title => protected'Modelling Lake Kivu water level variations over the last seven decades' (70 chars)
      journal => protected'Limnologica' (11 chars)
      year => protected2014 (integer)
      volume => protected47 (integer)
      issue => protected'' (0 chars)
      startpage => protected'21' (2 chars)
      otherpage => protected'33' (2 chars)
      categories => protected'East-African lakes; Lake Kivu; hydrological variability; modelling; Ruzizi I
          Hydropower Dam' (91 chars)
      description => protected'This study aimed at analysing the hydrological changes in the Lake Kivu Basi
         n over the last seven decades with focus on the response of the lake water l
         evel to meteorological factors and hydropower dam construction. Historical p
         recipitation and lake water levels were acquired from literature, local agen
         cies and from global databases in order to compile a coherent dataset. The n
         et lake inflow was modelled using a soil water balance model and the water l
         evels were reconstructed using a parsimonious lake water balance model. The 
         soil water balance shows that 370 mm yr<SUP>−1</SUP> (25%) of the precip
         itation in the catchment contributes to the runoff and baseflow whereas 1100
          mm yr<SUP>−1</SUP> (75%) contributes to the evapotranspiration. A revie
         w of the lake water balance resulted in the following estimates of hydrologi
         cal contributions: 55%, 25%, and 20% of the overall inputs from precipitatio
         n, surface inflows, and subaquatic groundwater discharge, respectively. The 
         overall losses were 58% and 42% for lake surface evaporation and outflow dis
         charge, respectively. The hydrological model used indicated a remarkable sen
         sitivity of the lake water levels to hydrometeorological variability up to 1
         977, when the outflow bed was artificially widened.' (1267 chars)
      serialnumber => protected'0075-9511' (9 chars)
      doi => protected'10.1016/j.limno.2014.02.003' (27 chars)
      uid => protected9054 (integer)
      _localizedUid => protected9054 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected9054 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6670, pid=124)
      originalId => protected6670 (integer)
      authors => protected'Pasche,&nbsp;N.; Schmid,&nbsp;M.; Vazquez,&nbsp;F.; Schubert,&nbsp;C.&nbsp;J
         .; Wüest,&nbsp;A.; Kessler,&nbsp;J.&nbsp;D.; Pack,&nbsp;M.&nbsp;A.; Reeburg
         h,&nbsp;W.&nbsp;S.; Bürgmann,&nbsp;H.' (190 chars)
      title => protected'Methane sources and sinks in Lake Kivu' (38 chars)
      journal => protected'Journal of Geophysical Research: Biogeosciences' (47 chars)
      year => protected2011 (integer)
      volume => protected116 (integer)
      issue => protected'G3' (2 chars)
      startpage => protected'G03006 (16 pp.)' (15 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'Unique worldwide, Lake Kivu stores enormous amounts of CH<sub>4</sub> and CO
         <sub>2</sub>. A recent study reported that CH<sub>4</sub> concentrations in 
         the lake have increased by up to 15% in the last 30 years and that accumulat
         ion at this rate could lead to catastrophic outgassing by ∼2100. This stud
         y investigates the present-day CH<sub>4</sub> formation and oxidation in Lak
         e Kivu. Analyses of <sup>14</sup>C and <sup>13</sup>C in CH<sub>4</sub> and 
         potential carbon sources revealed that below 260 m, an unusually high ∼65%
          of the CH<sub>4</sub> originates either from reduction of geogenic CO<sub>2
         </sub> with mostly geogenic H<sub>2</sub> or from direct inflows of geogenic
          CH<sub>4</sub>. Aerobic CH<sub>4</sub> oxidation, performed by close relati
         ves of type X CH<sub>4</sub>-oxidizing bacteria, is the main process prevent
         ing CH<sub>4</sub> from escaping to the atmosphere. Anaerobic CH<sub>4</sub>
          oxidation, carried out by CH<sub>4</sub>-oxidizing archaea in the SO<sub>4<
         /sub><sup>2−</sup>-reducing zone, was also detected but is limited by the 
         availability of sulfate. Changes in <sup>14</sup>C<sub>CH4</sub> and <sup>13
         </sup>C<sub>CH4</sub> since the 1970s suggest that the amount of CH<sub>4</s
         ub> produced from degrading organic material has increased due to higher acc
         umulation of organic matter. This, as well as the sudden onset of carbonates
          in the 1960s, has previously been explained by three environmental changes:
          (1) introduction of nonnative fish, (2) amplified subaquatic inflows follow
         ing hydrological changes, and (3) increased external inputs due to the fast 
         growing population. The resulting enhancement of primary production and orga
         nic matter sedimentation likely caused CH<sub>4</sub> to increase. However, 
         given the large proportion of old CH<sub>4</sub> carbon, we cannot exclude a
         n increased inflow of geogenic H<sub>2</sub> or CH<sub>4</sub>.' (1887 chars)
      serialnumber => protected'2169-8953' (9 chars)
      doi => protected'10.1029/2011JG001690' (20 chars)
      uid => protected6670 (integer)
      _localizedUid => protected6670 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected6670 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6493, pid=124)
      originalId => protected6493 (integer)
      authors => protected'Pasche,&nbsp;N.; Alunga,&nbsp;G.; Mills,&nbsp;K.; Muvundja,&nbsp;F.; Ryves,&
         nbsp;D.&nbsp;B.; Schurter,&nbsp;M.; Wehrli,&nbsp;B.; Schmid,&nbsp;M.' (144 chars)
      title => protected'Abrupt onset of carbonate deposition in Lake Kivu during the 1960s: response
          to recent environmental changes' (108 chars)
      journal => protected'Journal of Paleolimnology' (25 chars)
      year => protected2010 (integer)
      volume => protected44 (integer)
      issue => protected'4' (1 chars)
      startpage => protected'931' (3 chars)
      otherpage => protected'946' (3 chars)
      categories => protected'East Africa; nutrients; net and gross sedimentation; carbonates; diatoms; ec
         ological change; Tanganyika sardine' (111 chars)
      description => protected'This study interprets the recent history of Lake Kivu, a tropical lake in th
         e East African Rift Valley. The current gross sedimentation was characterize
         d from a moored sediment trap array deployed over 2 years. The past net sedi
         mentation was investigated with three short cores from two different basins.
          Diatom assemblages from cores were interpreted as reflecting changes in mix
         ing depth, surface salinity and nutrient availability. The contemporary sedi
         ment trap data indicate seasonal variability, governed by diatom blooms duri
         ng the annual mixing in the dry season, similar to Lakes Malawi and Tanganyi
         ka. The ratio of settling fluxes to net sediment accumulation rates implies 
         mineralization rates of 80–90% at the sediment-water interface. The sedime
         nt cores revealed an abrupt change ~40 years ago, when carbonate precipitati
         on started. Since the 1960s, deep-water methane concentrations, nutrient flu
         xes and soil mineral inputs have increased considerably and diatom assemblag
         es have altered. These modifications probably resulted from a combination of
          three factors, commonly altering lake systems: the introduction of a non-na
         tive fish species, eutrophication, and hydrological changes inducing greater
          upwelling. Both the fish introduction and increased rainfall occurred at th
         e time when the onset of carbonate precipitation was observed, whereas catch
         ment population growth accompanied by intensified land use increased the flu
         x of soil minerals already since the early twentieth century due to more int
         ense erosion.' (1533 chars)
      serialnumber => protected'0921-2728' (9 chars)
      doi => protected'10.1007/s10933-010-9465-x' (25 chars)
      uid => protected6493 (integer)
      _localizedUid => protected6493 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected6493 (integer)modified
      pid => protected124 (integer)
   3 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6097, pid=124)
      originalId => protected6097 (integer)
      authors => protected'Pasche,&nbsp;N.; Dinkel,&nbsp;C.; Müller,&nbsp;B.; Schmid,&nbsp;M.; Wüest,
         &nbsp;A.; Wehrli,&nbsp;B.' (101 chars)
      title => protected'Physical and biogeochemical limits to internal nutrient loading of meromicti
         c Lake Kivu' (87 chars)
      journal => protected'Limnology and Oceanography' (26 chars)
      year => protected2009 (integer)
      volume => protected54 (integer)
      issue => protected'6' (1 chars)
      startpage => protected'1863' (4 chars)
      otherpage => protected'1873' (4 chars)
      categories => protected'' (0 chars)
      description => protected'Lake Kivu is one of the large African Rift lakes situated between the Democr
         atic Republic of the Congo and Rwanda. In its permanently stratified hypolim
         nion, unusually high methane concentrations have increased further in recent
          decades. Because methanogenesis is, in part, dependent on supply of organic
          material from the photic zone, it is necessary to quantify upward nutrient 
         fluxes from the saline, nutrient-rich deep waters. These upward fluxes are m
         ainly driven by advection caused by subaquatic springs. Biogenic calcite pre
         cipitation drives surface-water depletion and deep-water enrichment of Ca<su
         p>2+</sup>, Sr<sup>2+</sup>, and Ba<sup>2+</sup>. Methane is mainly oxidized
          aerobically at the redox interface at 60 m, with a small contribution of an
         aerobic methane oxidation. A subaquatic spring that sustains the major chemo
         cline at 250 m depth was depleted of N, P, and CH<sub>4</sub>, and concentra
         tions of major ions were slightly lower than in the lake water of the same d
         epth. Enrichment of the deep waters with nutrients and CH<sub>4</sub> are dr
         iven by mineralization of settling organic material, whereas SiO<sub>2</sub>
          is influenced by uptake and mineralization of diatoms and inputs through su
         baquatic springs. Dissolved inorganic phosphorus and Si fluxes supplied by i
         nternal loading through upwelling were found to be lower than the estimation
         s for Lakes Malawi and Tanganyika. In contrast, N flux was within the lower 
         range for Lake Malawi, whereas it was assumed to be totally lost by denitrif
         ication in Lake Tanganyika. In Lake Kivu, nutrient uptake by primary product
         ion is three times higher than nutrient upward fluxes.' (1650 chars)
      serialnumber => protected'0024-3590' (9 chars)
      doi => protected'10.4319/lo.2009.54.6.1863' (25 chars)
      uid => protected6097 (integer)
      _localizedUid => protected6097 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected6097 (integer)modified
      pid => protected124 (integer)
   4 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=6113, pid=124)
      originalId => protected6113 (integer)
      authors => protected'Muvundja,&nbsp;F.&nbsp;A.; Pasche,&nbsp;N.; Bugenyi,&nbsp;F.&nbsp;W.&nbsp;B.
         ; Isumbisho,&nbsp;M.; Müller,&nbsp;B.; Namugize,&nbsp;J.-N.; Rinta,&nbsp;P.
         ; Schmid,&nbsp;M.; Stierli,&nbsp;R.; Wüest,&nbsp;A.' (204 chars)
      title => protected'Balancing nutrient inputs to Lake Kivu' (38 chars)
      journal => protected'Journal of Great Lakes Research' (31 chars)
      year => protected2009 (integer)
      volume => protected35 (integer)
      issue => protected'3' (1 chars)
      startpage => protected'406' (3 chars)
      otherpage => protected'418' (3 chars)
      categories => protected'internal loading; methane; nitrogen; phosphorus; primary production; river i
         nflows' (82 chars)
      description => protected'The primary production in meromictic Lake Kivu is sustained by external nutr
         ient inputs and by internal loading due to upwelling caused by sub-aquatic s
         ources. We present here the results of external loading of phosphorus (P), n
         itrogen (N) and silica (Si) by rivers and atmospheric deposition measured fr
         om 2006 to 2008. These external inputs are compared to internal loading. The
          input of soluble-reactive P (SRP), supplied in equal parts from rivers and 
         atmospheric deposition, adds up to 230 t P yr<SUP>–1</SUP>, 20 times less 
         than total P load. Ammonium (mainly via rainwater) and nitrate (mainly via r
         ivers) are primary sources of the dissolved N load (5400 t N yr<SUP>–1</SU
         P>), with both species contributing ∼50%. Dissolved Si input (40,000 t Si 
         yr<SUP>–1</SUP>) is unique in that only ∼60% enters by rivers, while the
          remaining ∼40% comes from sub-aquatic sources and atmospheric deposition 
         is negligible. Based on the molar nutrient ratios, we identify P as the limi
         ting factor for algae production. Despite the strong anthropogenic impact on
          the catchment and the high particle erosion (74 t km<SUP>–2</SUP> yr<SUP>
         –1</SUP>), the area-specific nutrient mobilization is rather low. The exte
         rnal nutrient input is therefore not the cause for the reported increase of 
         methane production in the last decades. External loading to the epilimnion p
         lays a lesser role for all three nutrients (∼10% for SRP, ∼25% for disso
         lved N and ∼45% for dissolved Si), as compared to the lake-internal loadin
         g by upwelling (90%, 75% and 55%, respectively). Lake Kivu, therefore, is si
         milar to other East African large lakes in that the internal loading exceeds
          the external loading. Despite the substantial uncertainty of the load estim
         ates of up to 50%, we can conclude that the observed nutrient input is consi
         stent with the primary production of 260 g C m<SUP>–2</SUP> yr<SUP>–1</S
         UP> recently measured by Sarmento et al. (2006) and also consistent with the
          lake-internal fluxes es...' (2038 chars)
      serialnumber => protected'0380-1330' (9 chars)
      doi => protected'10.1016/j.jglr.2009.06.002' (26 chars)
      uid => protected6113 (integer)
      _localizedUid => protected6113 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected6113 (integer)modified
      pid => protected124 (integer)

array(2 items)
   publications => '23901,22449,21238,19543,18541' (29 chars)
   libraryUrl => '' (0 chars)

array(5 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=23901, pid=124)
      originalId => protected23901 (integer)
      authors => protected'Bärenbold, F.; Kipfer, R.; Schmid, M.' (53 chars)
      title => protected'Dynamic modelling provides new insights into development and maintenance of 
         Lake Kivu's density stratification' (110 chars)
      journal => protected'Environmental Modelling and Software' (36 chars)
      year => protected2022 (integer)
      volume => protected147 (integer)
      issue => protected'' (0 chars)
      startpage => protected'105251 (15 pp.)' (15 chars)
      otherpage => protected'' (0 chars)
      categories => protected'Lake Kivu; Simstrat-AED2; 1d modelling; gas accumulation; hydrothermal groun
         dwater' (82 chars)
      description => protected'Lake Kivu is a 485 m deep, Central-East African rift lake with huge amounts 
         of carbon dioxide and methane dissolved in its stably stratified deep waters
         . In view of future large-scale methane extraction, one-dimensional numerica
         l modelling is an important and computationally inexpensive tool to analyze 
         the evolution of stratification and the content of gases in Lake Kivu. For t
         his purpose, we coupled the physical lake model Simstrat to the biogeochemic
         al library AED2. Compared to an earlier modelling approach, this coupled app
         roach offers several key improvements, most importantly the dynamic evaluati
         on of mixing processes over the whole water column, including a parameteriza
         tion for double-diffusive transport, and the density-dependent stratificatio
         n of groundwater inflows. The coupled model successfully reproduces today's 
         near steady-state of Lake Kivu, and we demonstrate that a complete mixing ev
         ent ∼2000 years ago is compatible with today's physical and biogeochemical
          state.' (995 chars)
      serialnumber => protected'1364-8152' (9 chars)
      doi => protected'10.1016/j.envsoft.2021.105251' (29 chars)
      uid => protected23901 (integer)
      _localizedUid => protected23901 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected23901 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=22449, pid=124)
      originalId => protected22449 (integer)
      authors => protected'Schmid, M.; Bärenbold, F.; Wüest, A.' (53 chars)
      title => protected'Methane extraction from Lake Kivu. Scientific background' (56 chars)
      journal => protected'' (0 chars)
      year => protected2021 (integer)
      volume => protected0 (integer)
      issue => protected'' (0 chars)
      startpage => protected'15 p' (9 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'' (0 chars)
      serialnumber => protected'' (0 chars)
      doi => protected'' (0 chars)
      uid => protected22449 (integer)
      _localizedUid => protected22449 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected22449 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=21238, pid=124)
      originalId => protected21238 (integer)
      authors => protected'Bärenbold, F.; Boehrer, B.; Grilli, R.; Mugisha, A.; vo
         n Tümpling, W.; Umutoni, A.; Schmid, M.' (131 chars)
      title => protected'No increasing risk of a limnic eruption at Lake Kivu: intercomparison study 
         reveals gas concentrations close to steady state' (124 chars)
      journal => protected'PLoS One' (8 chars)
      year => protected2020 (integer)
      volume => protected15 (integer)
      issue => protected'8' (1 chars)
      startpage => protected'e0237836 (14 pp.)' (17 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'Lake Kivu, East Africa, is well known for its huge reservoir of dissolved me
         thane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) in the stratified
          deep waters (below 250 m). The methane concentrations of up to ~ 20 mmol/l 
         are sufficiently high for commercial gas extraction and power production. In
          view of the projected extraction capacity of up to several hundred MW in th
         e next decades, reliable and accurate gas measurement techniques are require
         d to closely monitor the evolution of gas concentrations. For this purpose, 
         an intercomparison campaign for dissolved gas measurements was planned and c
         onducted in March 2018. The applied measurement techniques included on-site 
         mass spectrometry of continuously pumped sample water, gas chromatography of
          in-situ filled gas bags, an in-situ membrane inlet laser spectrometer senso
         r and a prototype sensor for total dissolved gas pressure (TDGP). We present
          the results of three datasets for CH<sub>4</sub>, two for CO<sub>2</sub> an
         d one for TDGP. The resulting methane profiles show a good agreement within 
         a range of around 5-10% in the deep water. We also observe that TDGP measure
         ments in the deep waters are systematically around 5 to 10% lower than TDGP 
         computed from gas concentrations. Part of this difference may be attributed 
         to the non-trivial conversion of concentration to partial pressure in gas-ri
         ch Lake Kivu. When comparing our data to past measurements, we cannot verify
          the previously suggested increase in methane concentrations since 1974. We 
         therefore conclude that the methane and carbon dioxide concentrations in Lak
         e Kivu are currently close to a steady state.' (1641 chars)
      serialnumber => protected'' (0 chars)
      doi => protected'10.1371/journal.pone.0237836' (28 chars)
      uid => protected21238 (integer)
      _localizedUid => protected21238 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected21238 (integer)modified
      pid => protected124 (integer)
   3 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=19543, pid=124)
      originalId => protected19543 (integer)
      authors => protected'Bärenbold,&nbsp;F.; Schmid,&nbsp;M.; Brennwald,&nbsp;M.&nbsp;S.; Kipfer,&nb
         sp;R.' (81 chars)
      title => protected'Missing atmospheric noble gases in a large, tropical lake: the case of Lake 
         Kivu, East-Africa' (93 chars)
      journal => protected'Chemical Geology' (16 chars)
      year => protected2020 (integer)
      volume => protected532 (integer)
      issue => protected'' (0 chars)
      startpage => protected'119374 (9 pp.)' (14 chars)
      otherpage => protected'' (0 chars)
      categories => protected'noble gases; Lake Kivu; depletion; groundwater; volcanic region' (63 chars)
      description => protected'Lake Kivu is a 485 m deep tropical rift lake in East-Africa and well-known
          for its very high concentrations of dissolved carbon dioxide and methane in
          the stratified deep waters. In view of future large-scale methane extractio
         n for power production, there is a need for predicting the evolution of gas 
         concentrations and lake stability using numerical modelling. However, knowle
         dge about the geochemical origin and transport processes affecting dissolved
          gases in the lake is still partially missing. Due to their inert nature, th
         e analysis of dissolved noble gases can help to shed light on such questions
         . To learn more about transport processes in Lake Kivu, we extended a well-e
         stablished sampling method for dissolved noble gases to work in the lake's h
         igh gas pressure waters. The results of our analysis show a distinct non-atm
         ospheric isotopic signal in the deep waters (below 250 m) with <sup>3</sup
         >He/<sup>4</sup>He and <sup>40</sup>Ar/<sup>36</sup>Ar ratios ~250% and ~20%
          higher than air saturated water (ASW). Moreover, the gas concentration prof
         iles reveal a striking lack of atmospheric noble gases in the deep waters wi
         th respect to ASW. While Ne is depleted by ~45%, the more soluble <sup>36</s
         up>Ar and Kr even decrease by ~70%. In contrast, <sup>4</sup>He concentratio
         ns increase with depth by a factor of up to ~600. We attribute this excess H
         e and the increases in <sup>3</sup>He/<sup>4</sup>He and <sup>40</sup>Ar/<su
         p>36</sup>Ar to the inflow of magmatic gases into Lake Kivu, along with a si
         gnificant contribution of radiogenic <sup>4</sup>He. To explain the depletio
         n of atmospheric noble gases, we present and discuss three different scenari
         os, namely continuous outgassing, the inflow of depleted groundwater and a l
         arge past outgassing event. Due to the best agreement with our observations,
          we conclude that the inflow of depleted groundwater is likely responsible f
         or the observed atmospheric noble gas depletions.' (1949 chars)
      serialnumber => protected'0009-2541' (9 chars)
      doi => protected'10.1016/j.chemgeo.2019.119374' (29 chars)
      uid => protected19543 (integer)
      _localizedUid => protected19543 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected19543 (integer)modified
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      originalId => protected18541 (integer)
      authors => protected'Schmid,&nbsp;M.; Bärenbold,&nbsp;F.; Boehrer,&nbsp;B.; Darchambeau,&nbsp;F.
         ; Grilli,&nbsp;R.; Triest,&nbsp;J.; von Tümpling,&nbsp;W.' (134 chars)
      title => protected'Intercalibration campaign for gas concentration measurements in Lake Kivu' (73 chars)
      journal => protected'' (0 chars)
      year => protected2019 (integer)
      volume => protected0 (integer)
      issue => protected'' (0 chars)
      startpage => protected'64&nbsp;p' (9 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'1.The 2018 intercalibration campaign aimed at quantifying the methane (CH<su
         b>4</sub>) and carbon dioxide (CO<sub>2</sub>) gas content and the recharge 
         rate of CH<sub>4</sub> in Lake Kivu using a range of different measurement m
         ethods. Measurements were performed by research teams from the Helmholtz Cen
         tre for Environmental Research (UFZ) in Magdeburg (Germany), the Swiss Feder
         al Institute for Aquatic Science and Technology (Eawag, Switzerland), the Fr
         ench National Centre for Scientific Research (CNRS) in Grenoble (France), an
         d from KivuWatt Ltd (Kigali, Rwanda). <br/> 2. The following measurement met
         hods were applied: two sensors for the in-situ observation of total dissolve
         d gas pressure; two sensors for the in-situ observation of the partial press
         ure of dissolved CH<sub>4</sub>; and two methods for quantifying the concent
         rations of dissolved CH<sub>4</sub> and CO<sub>2</sub> in samples retrieved 
         from the lake either using sampling bags or a tubing system. These methods w
         ere specifically customized for the application under the special conditions
          in Lake Kivu. Since some of the methods quantify partial pressures of CH<su
         b>4</sub> and/or CO<sub>2</sub>, and other methods quantify their concentrat
         ions, a procedure for converting between partial pressures and concentration
         s was developed and implemented. <br/> 3. The observations yielded a consist
         ent picture of the vertical profiles of dissolved concentrations of CH<sub>4
         </sub> and CO<sub>2</sub> as well as the total gas pressures in Lake Kivu. T
         he observed variability between the datasets is related to the limited accur
         acy of the different measurement methods.<br/> 4. The observed CH<sub>4</sub
         > concentrations were within the range of previous observations. However, in
          the resource zone (below 260 m depth), they were approximately 5-20 % below
          the concentrations measured by M. Halbwachs and J.-C. Tochon in 2003, which
          had previously been used as the standard for estimating the CH<sub>4</sub> 
         content in the lake.<br/...' (3614 chars)
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      doi => protected'' (0 chars)
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