Tracing bottom water oxygenation with sedimentary Mn/Fe ratios in Lake Zurich, Switzerland

Naeher, Sebastian; Gilli, Adrian; North, Ryan P.; Hamann, Yvonne; Schubert, Carsten J.

doi:10.1016/j.chemgeo.2013.06.006

Cited by 232 publications

(186 citation statements)

References 41 publications

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“…The relative trace metal concentrations determined in the core were compared with the oxygen concentrations measured in the water column to assess the potential of trace metals as indicators of deep-water hypoxia. Manganese (Mn) peaks in the sediment clearly tend to occur in late winter and spring, coinciding with the spring deep-water oxygen maxima, whereas iron (Fe) exhibits peaks in autumn and winter (Naeher et al, 2013b, and references therein). Naeher et al (2013b) showed that the Fe signal is mainly governed by calcite dilution.…”

Section: Long-term Oxygenation History -Examples From Swiss Lakes Andmentioning

confidence: 99%

“…Manganese (Mn) peaks in the sediment clearly tend to occur in late winter and spring, coinciding with the spring deep-water oxygen maxima, whereas iron (Fe) exhibits peaks in autumn and winter (Naeher et al, 2013b, and references therein). Naeher et al (2013b) showed that the Fe signal is mainly governed by calcite dilution. The maximum Mn XRF counts, when normalized by the Fe XRF data measured at the same depth, correlated well with the maximum three-month running mean oxygen concentrations in the water column at 135 m (Fig.…”

Section: Long-term Oxygenation History -Examples From Swiss Lakes Andmentioning

confidence: 99%

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Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

et al. 2014

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Abstract. In this paper we provide an overview of new knowledge on oxygen depletion (hypoxia) and related phenomena in aquatic systems resulting from the EU-FP7 project HYPOX ("In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and landlocked water bodies", www.hypox.net). In view of the anticipated oxygen loss in aquatic systems due to eutrophication and climate change, HYPOX was set up to improve capacities to monitor hypoxia as well as to understand its causes and consequences.Temporal dynamics and spatial patterns of hypoxia were analyzed in field studies in various aquatic environments, including the Baltic Sea, the Black Sea, Scottish and Scandinavian fjords, Ionian Sea lagoons and embayments, and Swiss lakes. Examples of episodic and rapid (hours) occurrences of hypoxia, as well as seasonal changes in bottom-water oxygenation in stratified systems, are discussed. Geologically driven hypoxia caused by gas seepage is demonstrated. Using novel technologies, temporal and spatial patterns of watercolumn oxygenation, from basin-scale seasonal patterns to meter-scale sub-micromolar oxygen distributions, were resolved. Existing multidecadal monitoring data were used to demonstrate the imprint of climate change and eutrophication on long-term oxygen distributions. Organic and inorganic proxies were used to extend investigations on past oxygen conditions to centennial and even longer timescales that cannot be resolved by monitoring. The effects of hypoxia on faunal communities and biogeochemical processes were also addressed in the project. An investigation of benthic fauna is presented as an example of hypoxia-devastated benthic communities that slowly recover upon a reduction in eutrophication in a system where naturally occurring hypoxia overlaps with anthropogenic hypoxia. Biogeochemical investigations reveal that oxygen intrusions have a strong effect on the microbially mediated redox cycling of elements. Observations and modeling studies of the sediments demonstrate the effect of seasonally changing oxygen conditions on benthic mineralization pathways and fluxes. Data quality and access are crucial in hypoxia research. Technical issues are therefore also addressed, including the availability of suitable sensor technology to resolve the gradual changes in bottom-water oxygen in marine systems that can be expected as a result of climate change. Using cabled observatories as examples, we show how the benefit of continuous oxygen monitoring can be maximized by adopting proper quality control. Finally, we discuss strategies for state-of-the-art data archiving and dissemination in compliance with global standards, and how ocean observations can contribute to global earth observation attempts.

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Section: Long-term Oxygenation History -Examples From Swiss Lakes Andmentioning

confidence: 99%

Section: Long-term Oxygenation History -Examples From Swiss Lakes Andmentioning

confidence: 99%

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

et al. 2014

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“…Well-developed benthic algal communities can reduce total phosphorus availability for phytoplankton through uptake and maintain high redox potential to prevent sedimentary phosphorus release to the water (Liboriussen & Jeppesen, 2003). The low Fe/Mn (Naeher et al, 2013) and high Fe/P ratios support this interpretation because Fe/P ratios [15-20 usually prevent phosphorus release (Jensen et al, 1992). Therefore, it appears that these feedbacks maintained high water transparency despite increased trophic status (Scheffer & Nes, 2007).…”

Section: Discussionmentioning

confidence: 56%

Disentangling natural and anthropogenic drivers of changes in a shallow lake using palaeolimnology and historical archives

et al. 2015

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Shallow lakes are susceptible to catastrophic regime shifts characterised by the presence or absence or macrophytes. However, the long-term controls on macrophyte succession in shallow lakes are incompletely understood. To investigate this, we analysed multiple sediment proxies in Lake Rotcze (Eastern Poland), a small, shallow and densely macrophyte-covered lake to (1) reconstruct the 'reference conditions' (sensu WFD) and development of the lake in recent centuries, (2) compare historical evidence with the sedimentary record, and (3) identify the natural and anthropogenic drivers of macrophyte succession. Before the twentieth century, conditions in the lake may be referred to as 'reference conditions'. Subsequently forest clearance in the catchment resulted in lower water transparency, but concurrent catchment drainage lowered water levels and increased macrophyte development. Since 1950 elevated nutrient supply and climatically driven increases in water levels led to the deterioration of water transparency and partial macrophyte withdrawal. At the end of the twentieth century lake-level drawdown led to low phytoplankton biomass and clear water creating a novel ecosystem where macrophytes invade the whole lake. These patterns suggest that both natural and anthropogenically induced water level fluctuations have been critical drivers of macrophyte development.

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“…Given the lack of any significant relationship between the 100·Mn/Fe ratio and oxygen deficits arising in waters, there may be confirmation of the idea that both are released into the water column with similar efficiency. Nevertheless, the oxidation of Fe(II) is known to proceed more rapidly than that of Mn(II) [Naeher et al 2013], while the involvement of numerous interdependent transformation processes leads to a complex pattern describing the presence of the redox-sensitive trace metals.…”

Section: Discussionmentioning

confidence: 99%

“…Both elements act to render phosphate inactive, in this way limiting processes of eutrophication [Bartoszek and Tomaszek 2011]. The effect is highly dependent on the oxidation and reduction of the coupled pairs Fe(II)/Fe(III) and Mn(II)/Mn(IV), which result either in precipitation or dissolution -commonly with phosphate [Gantzer et al 2009, Naeher et al 2013, Dunalska et al 2015. A further connected result may be intensification of the processes by which autochthonous organic matter is first produced and then decomposes, and the latter process may in turn give rise to oxygen deficits in the near-bottom zone.…”

Section: Introductionmentioning

confidence: 99%

Influence of Sedimentary Fe and Mn on the Oxygenation of Overlying Waters in Dam Reservoirs

Koszelnik¹,

Bartoszek²

2018

J. Ecol. Eng.

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This paper reports the work to determine the impact that concentrations of manganese (Mn) and iron (Fe) in the bottom sediments of shallow dam reservoirs exert upon the dissolved oxygen concentrations of overlying waters. Specifically, the work was conducted in the period of 2013-2014 in six shallow artificial reservoirs located in SE Poland. The waters of all the reservoirs studied are relatively well oxygenated, though both supersaturation and anoxic conditions are observed seasonally across the 50-150% range. The reported reactions of bottom sediments were between pH 7.7 and 8.2, while the mean concentrations of Mn and Fe were found to vary widely from site to site (Mn from 0.068 to 1.48 g/kg d.w. and Fe from 2.48 to 24.0 g/kg d.w.). It was not possible to demonstrate any direct relationship between sediment Fe and Mn concentrations, the Mn/Fe ratio or pH on the one hand and the oxygenation of reservoir waters on the other. However, multiple regression analysis did allow for the identification of a significant influence of both Mn content and sediment pH on the oxygen concentration in reservoir waters. In simple terms, both an increase in Mn and a decrease in pH can be said to result in more fully aerobic conditions in waters.

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Tracing bottom water oxygenation with sedimentary Mn/Fe ratios in Lake Zurich, Switzerland

Cited by 232 publications

References 41 publications

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Disentangling natural and anthropogenic drivers of changes in a shallow lake using palaeolimnology and historical archives

Influence of Sedimentary Fe and Mn on the Oxygenation of Overlying Waters in Dam Reservoirs

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