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Bistability in the redox chemistry of sediments and oceans
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For most of Earth’s history, the ocean’s interior was pervasively anoxic and showed occasional shifts in ocean redox chemistry between iron-buffered and sulfide-buffered states. These redox transitions are most often explained by large changes in external inputs, such as a strongly altered delivery of iron and sulfate to the ocean, or major shifts in marine productivity. Here, we propose that redox shifts can also arise from small perturbations that are amplified by nonlinear positive feedbacks within the internal iron and sulfur cycling of the ocean. Combining observational evidence with biogeochemical modeling, we show that both sedimentary and aquatic systems display intrinsic iron–sulfur bistability, which is tightly linked to the formation of reduced iron–sulfide minerals. The possibility of tipping points in the redox state of sediments and oceans, which allow large and nonreversible geochemical shifts to arise from relatively small changes in organic carbon input, has important implications for the interpretation of the geological rock record and the causes and consequences of major evolutionary transitions in the history of Earth’s biosphere.
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Bistability in the redox chemistry of sediments and oceans
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For most of Earth’s history, the ocean’s interior was pervasively anoxic and showed occasional shifts in ocean redox chemistry between iron-buffered and sulfide-buffered states. These redox transitions are most often explained by large changes in external inputs, such as a strongly altered delivery of iron and sulfate to the ocean, or major shifts in marine productivity. Here, we propose that redox shifts can also arise from small perturbations that are amplified by nonlinear positive feedbacks within the internal iron and sulfur cycling of the ocean. Combining observational evidence with biogeochemical modeling, we show that both sedimentary and aquatic systems display intrinsic iron–sulfur bistability, which is tightly linked to the formation of reduced iron–sulfide minerals. The possibility of tipping points in the redox state of sediments and oceans, which allow large and nonreversible geochemical shifts to arise from relatively small changes in organic carbon input, has important implications for the interpretation of the geological rock record and the causes and consequences of major evolutionary transitions in the history of Earth’s biosphere
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RBINS Staff Publications 2020
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Black adzes in the Early Neolithic of Belgium. Contribution of the Raman microspectrometry and petrography in the characterization and sourcing
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Ancient Neolithic (Linear Pottery Culture) adzes originate from settlements and workshops accompany the neolithization of Belgium. They are made from a wide range of extraregional lithic raw materials such as metamorphic green rocks (amphibolite) and black volcanic rocks (‘basalt’) beside more local or regional raw material as flints, light-coloured (sedimentary and lightly metamorphic) quartzites and fine-grained black rocks. Another material source included black lydites (Cambrian nodular phtanite of Céroux-Mousty and Lower Namurian banded phtanites) and dark grey Lower Namurian silicified sandstones called ‘Micaceous sandstones of Horion-Hozémont’. The discovery of the workshop of Noir Fontaine near the city of Liège in the 1970s and 1980s provides exceptional assemblage available for updating analytical studies. This research focuses on the multi-scale characterization, the discrimination and sourcing of the different types of fine-grained black materials composing Ancient Neolithic adzes found in Belgium. Their black colour results from finely dispersed organic matter, but the absence of palynomorphs does not allow a biostratigraphic ascription. Additional petrographical analyses (Optical Petrography - OP, Scanning Electronic Microscopy - SEM), X-ray diffraction (XRD), chemical analyses (Energy Dispersive Spectroscopy - EDS) and measuring the degree of graphitization of the organic matter through Raman microspectrometry have been decisive in identifying the geological and geographical provenances by comparing the acquired results with geological reference samples collected in the field or through reference collections. The distribution of the different black coloured rocks shows that Cambrian lydites are coming from a very restricted area and were preferred to other more local rock sources.
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RBINS Staff Publications 2021
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Board games as scientific communication tools for black-box methodologies: the principles of the geo-techno-economic PSS III simulator translated into an interactive educational game
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RBINS Staff Publications 2016
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Body distribution of toxic peptides in larvae of a pergid and an argid sawfly species
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RBINS Staff Publications 2020
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Body length estimation of the European eel Anguilla anguilla on the basis of isolated skeletal elements
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Using a large series of dry skeletons of modern European eel Anguilla anguilla (Linnaeus, 1758) from Belgium and the Netherlands, the relationship between fish length and individual bone measurements is investigated. The aim of the study is to provide adequate regression equations between both parameters. This methodology is relevant for both palaeoecological and ecological researches since isolated skeletal elements survive in large numbers on archaeological sites and in the stomach contents, faeces or regurgitations of piscivorous animals. The predictive value for the length estimations is explored for various skeletal elements and the accuracy of the obtained regression formulae is compared to that of the formulae already existing in literature. Particular attention is paid to the use of vertebrae, taking into account that different morphotypes can be distinguished amongst them.
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RBINS Staff Publications
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Body size and dispersal mode as key traits determining metacommunity structure of aquatic organisms
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RBINS Staff Publications
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Body size and dispersal mode as key traits determining metacommunity structure of aquatic organisms
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RBINS Staff Publications
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Body-size shifts in aquatic and terrestrial urban communities
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Body size is intrinsically linked to metabolic rate and life-history traits, and is a crucial determinant of food webs and community dynamics1,2. The increased temperatures associated with the urban-heat-island effect result in increased metabolic costs and are expected to drive shifts to smaller body sizes3. Urban environments are, however, also characterized by substantial habitat fragmentation4, which favours mobile species. Here, using a replicated, spatially nested sampling design across ten animal taxonomic groups, we show that urban communities generally consist of smaller species. In addition, although we show urban warming for three habitat types and associated reduced community-weighted mean body sizes for four taxa, three taxa display a shift to larger species along the urbanization gradients. Our results show that the general trend towards smaller-sized species is overruled by filtering for larger species when there is positive covariation between size and dispersal, a process that can mitigate the low connectivity of ecological resources in urban settings5. We thus demonstrate that the urban-heat-island effect and urban habitat fragmentation are associated with contrasting community-level shifts in body size that critically depend on the association between body size and dispersal. Because body size determines the structure and dynamics of ecological networks1, such shifts may affect urban ecosystem function.
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RBINS Staff Publications 2018
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Bolong yixianensis gen. et sp. nov.: a new iguanodontoid dinosaur from the Yixian Formation of Western Liaoning, China
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RBINS Staff Publications
