Into the abyss of Lake Geneva: the elemo interdisciplinary field investigation using the MIR submersibles

Wüest, Alfred; Anselmetti, Flavio S.; Arey, J. Samuel; Ibelings, Bastiaan Willem; Loizeau, Jean‐Luc; Vennemann, Torsten; Lemmin, Ulrich

doi:10.1007/s00027-014-0353-8

Cited by 6 publications

(7 citation statements)

References 28 publications

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“…The detection of the sediment‐water interface (SWI) is critical when investigating SOU. In Lake Geneva, sediment and water are distinctly separated by a defined SWI as observed during MIR submersible measurements in 2014 (Wüest et al ). As our instrument was very slowly but continuously sinking into the sediment throughout the experiments (by less than 1 mm h −1 ), we had to perform accurate SWI detection measurements prior to each profile.…”

Section: Methodsmentioning

confidence: 89%

Using small‐scale measurements to estimate hypolimnetic oxygen depletion in a deep lake

Schwefel

Steinsberger

Bouffard

et al. 2017

Limnology & Oceanography

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Low oxygen concentrations in lakes and reservoirs are an ongoing environmental concern, particularly in light of increasing anthropogenic activity and climate change. Oxygen depletion processes in lakes are still not completely understood and a variety of models have been proposed based on limited field observations. Here, we present field measurements of oxygen depletion processes in a deep lake, Lake Geneva (Switzerland). The aim of this study was to quantify three basic processes controlling hypolimnetic oxygen depletion and their relative contribution to the total oxygen depletion (TOD) rate. Sediment oxygen uptake (SOU) and the flux of reduced substances were estimated based on oxygen microprofile measurements and sediment core data of reduced substances. Acoustic Doppler current profiler measurements and hydrodynamic modeling were used to ensure that SOU was measured under typical hydrodynamic conditions. Comparison with long‐term monitoring data allowed for an estimate of the relative importance of SOU and water column mineralization (WCM). Results show a decrease in both SOU and WCM down to mid‐depth which could not be explained by changes in hydrodynamic conditions or temperature. Below mid‐depth, TOD increased due to an enhanced sediment area to water volume ratio (α). This vertical pattern of oxygen depletion is driven by (1) lake morphometry paired with increasing α, and (2) decreasing organic matter mineralization in the water column with depth. The findings are explained by a model which separates the oxygen depletion into an exponentially decreasing component, representing the fast‐decaying fraction of the organic matter, and a constant background component.

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Section: Methodsmentioning

confidence: 89%

Using small‐scale measurements to estimate hypolimnetic oxygen depletion in a deep lake

Schwefel

Steinsberger

Bouffard

et al. 2017

Limnology & Oceanography

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“…Lakes and reservoirs serve multiple purposes (Brookes et al 2004;Wüest et al 2013). Apart from providing clean and safe drinking water, they can be recreation centers, have high cultural value, and provide numerous ecosystem services (e.g., Ge et al 2010;Ji 2008;Kristal et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Direct effects of dominant winds on residence and travel times in the wide and open lacustrine embayment: Vidy Bay (Lake Geneva, Switzerland)

et al. 2013

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Numerical simulations were carried out to determine the residence (or flushing) time of water in Vidy Bay (north shore of Lake Geneva) for different meteorological conditions. A hydrodynamic model (Delft3D-FLOW) was applied to simulate the flow field in the embayment during 2010 and January 2011. Using these results, particle tracking was applied to estimate transport of wastewater effluent discharged into the embayment. The model predictions compared well with published field measurements of dissolved species (as given by electrical conductivity profiles) within the wastewater. The pelagic boundary of the embayment was defined by the largest within-bay gyre. Based on this definition, particle tracking was used to quantify the residence time under dominant wind conditions. Similarly, particle tracking was used to determine the travel time (i.e., time to exit the embayment) for each of Vidy Bay's three inflows (stream, stormwater and wastewater effluent). Although the wind field over the lake is variable, current patterns in the embayment can be simulated using the hydrodynamic model forced by a spatially uniform wind field. For a given wind speed, the main factor influencing residence and travel times is the wind angle. The presence of gyres leads to high mean residence times with large variability. As the wind direction becomes more aligned with the shoreline (i.e., with increasing westerly or easterly components), longshore currents dominate. These disrupt gyre formation and markedly reduce the mean and variability of embayment residence time. The numerical model was utilized to assess the potential for plume movement (in plan) from above the wastewater effluent outfall towards one of Lausanne's drinking water intakes. In the most direct pathway, westward longshore currents can move water from the embayment to the water column above the intake location.

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“…Lake Geneva is one of the largest fresh surface water resources in Europe, having a surface area of 580 km 2 and a maximum depth of 310 m. 114 It is the main drinking water source for more than 520 000 people (Figure S1). 115 Commercial and recreational fishing in Lake Geneva together amount to approximately 1000 tons of fish per year.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…We collected sediment cores from four locations of the lake (Figure 1), using either a Benthos gravity corer from a surface vessel (Sites 1–4) or a tube core from the robotic arm of a human-occupied Mir submersible (Site 2) during the Elemo field campaign in the summer of 2011. 114 The sediment samples were collected from locations having total depths of 192 m (Site 1), 310 m (Site 2), 236 m (Site 3), and 188 m (Site 4). Site 1 was located at 46.4945°N and 6.5796°E (World Geodetic System, WGS84), Site 2 was located at 46.4390°N and 6.6130°E, Site 3 was located at 46.4183°N and 6.7801°E, and Site 4 was located at 46.4345°N and 6.8551°E.…”

Section: Experimental Methodsmentioning

confidence: 99%

Elevated Concentrations of 4-Bromobiphenyl and 1,3,5-Tribromobenzene Found in Deep Water of Lake Geneva Based on GC×GC-ENCI-TOFMS and GC×GC-μECD

et al. 2017

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We quantified the concentrations of two little-studied brominated pollutants, 1,3,5-tribromobenzene (TBB) and 4-bromobiphenyl (4BBP), in the deep water column and sediments of Lake Geneva. We found aqueous concentrations of 625 ± 68 pg L –1 for TBB and 668 ± 86 pg L –1 for 4BBP over a depth range of 70–191.5 m (near-bottom depth), based on duplicate measurements taken at five depths during three separate 1 month sampling periods at our sampling site near Vidy Bay. These levels of TBB and 4BBP were 1 or 2 orders of magnitude higher than the quantified aqueous concentrations of the components of the pentabrominated biphenyl ether technical mixture, which is a flame retardant product that had a high production volume in Europe before 2001. We observed statistically significant vertical concentration trends for both TBB and 2,2′,4,4′,6-pentabromobiphenyl ether in the deep water column, which indicates that transport and/or degradation processes affect these compounds. These measurements were enabled by application of a comprehensive two-dimensional gas chromatograph coupled to an electron capture negative chemical ionization time-of-flight mass spectrometer (GC×GC-ENCI-TOFMS) and to a micro-electron capture detector (GC×GC-μECD). GC×GC-ENCI-TOFMS and GC×GC-μECD were found to be >10× more sensitive toward brominated pollutants than conventional GC×GC-EI-TOFMS (with an electron impact (EI) ionization source), the latter of which had insufficient sensitivity to detect these emerging brominated pollutants in the analyzed samples. GC×GC also enabled the estimation of several environmentally relevant partitioning properties of TBB and 4BBP, further confirming previous evidence that these pollutants are bioaccumulative and have long-range transport potential.

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Into the abyss of Lake Geneva: the elemo interdisciplinary field investigation using the MIR submersibles

Cited by 6 publications

References 28 publications

Using small‐scale measurements to estimate hypolimnetic oxygen depletion in a deep lake

Using small‐scale measurements to estimate hypolimnetic oxygen depletion in a deep lake

Direct effects of dominant winds on residence and travel times in the wide and open lacustrine embayment: Vidy Bay (Lake Geneva, Switzerland)

Elevated Concentrations of 4-Bromobiphenyl and 1,3,5-Tribromobenzene Found in Deep Water of Lake Geneva Based on GC×GC-ENCI-TOFMS and GC×GC-μECD

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