Modeling Geochemically Caused Permanent Stratification in Lake Waldsee (Germany)

Moreira, Santiago; Boehrer, Bertram; Schultze, Martin; Dietz, Severine; Samper, Javier

doi:10.1007/s10498-011-9133-4

Cited by 13 publications

(12 citation statements)

References 45 publications

(41 reference statements)

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“…This case presented a meromictic open pit lake Dietz et al, 2008Dietz et al, , 2012von Rohden et al, 2010;Moreira et al, 2011) of moderate salinity (0.22 psu in the mixolimnion and 0.6 psu in the monimolimnion, Moreira et al, 2011), but its composition differed from the usual carbonate or chloride waters. Composition was obtained from Dietz et al (2008Dietz et al ( , 2012.…”

Section: Assessmentsmentioning

confidence: 98%

“…In order to include also water with a rather unusual composition, we chose two water samples from a meromictic open pit lake, the Waldsee, which contains large amounts of sulfate and dissolved iron (e.g. Dietz et al, 2008Dietz et al, , 2012Boehrer et al, 2009;von Rohden et al, 2010;Moreira et al, 2011). Finally, we used seawater, of which the composition is known at high accuracy, as a reference water for a standard comparison.…”

Section: Assessmentsmentioning

confidence: 99%

“…Based on partial molal volumes (RHOMV), Dietz et al (2012) separated the contributions of solutes for freshwater lakes. Moreira et al (2011) based density on the composition of solutes in their model to reproduce the permanent stratification of the Waldsee numerically using RHOMV to include the reactivity of substances in the density (see also Nixdorf and Boehrer, 2015).…”

Section: Introductionmentioning

confidence: 99%

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A practical approach to lake water density from electrical conductivity and temperature

Moreira

Schultze

Rahn

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. Density calculations are essential to study stratification, circulation patterns, internal wave formation and other aspects of hydrodynamics in lakes and reservoirs. Currently, the most common procedure is the use of CTD (conductivity, temperature and depth) profilers and the conversion of measurements of temperature and electrical conductivity into density. In limnic waters, such approaches are of limited accuracy if they do not consider lake-specific composition of solutes, as we show. A new approach is presented to correlate density and electrical conductivity, using only two specific coefficients based on the composition of solutes. First, it is necessary to evaluate the lake-specific coefficients connecting electrical conductivity with density. Once these coefficients have been obtained, density can easily be calculated based on CTD data. The new method has been tested against measured values and the most common equations used in the calculation of density in limnic and ocean conditions. The results show that our new approach can reproduce the density contribution of solutes with a relative error of less than 10 % in lake waters from very low to very high concentrations as well as in lakes of very particular water chemistry, which is better than all commonly implemented density calculations in lakes. Finally, a web link is provided for downloading the corresponding density calculator.

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Section: Assessmentsmentioning

confidence: 98%

Section: Assessmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A practical approach to lake water density from electrical conductivity and temperature

Moreira

Schultze

Rahn

et al. 2016

Hydrol. Earth Syst. Sci.

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“…One potential reason for the discrepancy in the excursions of both curves is the precipitation of iron hydroxide flocks on oxic sediments close to the side walls following a decrease in chemocline height (Schultze et al, 2011). A subsequent rise of the chemocline would lead to a delayed re-dissolution of these flocks, which meant that this mechanism would be able to buffer fluctuations in the electrical conductivity.…”

Section: Preservation Of Permanent Stratification By the Iron-redox Cmentioning

confidence: 99%

Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake

Nixdorf

Boehrer

2015

Hydrol. Earth Syst. Sci.

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Abstract. Lake stratification controls the cycling of dissolved matter within the water body. This is of particular interest in the case of meromictic lakes, where permanent density stratification of the deep water limits vertical transport, and a chemically different (reducing) milieu can be established. As a consequence, the geochemical setting and the mixing regime of a lake can stabilize each other mutually. We attempt a quantitative approach to the contribution of chemical reactions sustaining the density stratification. As an example, we chose the prominent case of iron meromixis in Waldsee near Doebern, a small lake that originated from near-surface underground mining of lignite. From a data set covering 4 years of monthly measured electrical conductivity profiles, we calculated summed conductivity as a quantitative variable reflecting the amount of electro-active substances in the entire lake. Seasonal variations followed the changing of the chemocline height. Coinciding changes of electrical conductivities in the monimolimnion indicated that a considerable share of substances, precipitated by the advancing oxygenated epilimnion, re-dissolved in the remaining anoxic deep waters and contributed considerably to the density stratification. In addition, we designed a lab experiment, in which we removed iron compounds and organic material from monimolimnetic waters by introducing air bubbles. Precipitates could be identified by visual inspection. Eventually, the remaining solutes in the aerated water layer looked similar to mixolimnetic Waldsee water. Due to its reduced concentration of solutes, this water became less dense and remained floating on nearly unchanged monimolimnetic water. In conclusion, iron meromixis as seen in Waldsee did not require two different sources of incoming waters, but the inflow of iron-rich deep groundwater and the aeration through the lake surface were fully sufficient for the formation of iron meromixis.

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“…The link between meromicticity and high offset values may be addressed schematically (with no attempts to model change in geochemistry like in Moreira et al 2011) by eliminating the chemocline (i.e. extending high K (z) values down to the bottom).…”

Section: Understanding the Apparent Past Reservoir Effect In Lac Pavinmentioning

confidence: 99%

Carbon Cycling and Organic Radiocarbon Reservoir Effect in a Meromictic Crater Lake (Lac Pavin, Puy-de-Dôme, France)

Albéric

2013

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ABSTRACT. Lac Pavin is a meromictic maar lake for which the interpretation of sediment radiocarbon dates is complicated by the existence of a largely undefined reservoir effect resulting from degradation of carbon stored in the bottom layer of the water column. A data set of the contemporary 14 C distribution of dissolved and particulate organic pools in the water column is presented to address this issue. Dissolved inorganic carbon (DIC) and organic carbon (DOC), plankton, suspended particulate organic carbon (POC susp ), sinking POC (POC sink ), and bottom sediment organic carbon (SOC) were analyzed. Presentday  14 C values of DIC were measured ranging from -750‰ in the monimolimnion to atmospheric values in lake surface waters and in spring inlet waters. A range of  14 C values between -200 and -300‰ was observed for superficial POC susp , POC sink , SOC, and DOC. This relatively uniform 14 C offset of the exported organic production from the surface waters to the bottom represents a contemporary reservoir effect of ~2500 yr. Laminated buried sediment samples and terrestrial vegetal macro-remains were used to evaluate temporal reservoir effect variations since the formation of the crater lake (7 ka cal BP). Buried sediment layers presented a similar offset or showed larger differences between  14 C values of bulk sediment and terrestrial plant remains (-400 to -500‰). Furthermore, an almost 0-yr reservoir effect was inferred from the sediment layers deposited just above the volcanic bedrock at the early flooding of the crater, and increasing slightly within the first centuries of the lake's history. A second objective was to tentatively model a defined scenario of the cycling of carbon in the lake capable of predicting a modern reservoir effect. Alternative scenarios were then tested for which a larger contribution of deeper DIC would provide a model compatible with larger past reservoir effects. It is concluded that using  14 C SOC variation in laminated lake sediments as a proxy of paleolimnological conditions may be valuable provided that more data on the dynamics of the 14 C composition of plankton and more detailed sampling of laminated sediment layers are available.

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Modeling Geochemically Caused Permanent Stratification in Lake Waldsee (Germany)

Cited by 13 publications

References 45 publications

A practical approach to lake water density from electrical conductivity and temperature

A practical approach to lake water density from electrical conductivity and temperature

Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake

Carbon Cycling and Organic Radiocarbon Reservoir Effect in a Meromictic Crater Lake (Lac Pavin, Puy-de-Dôme, France)

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