1,192 results on '"Middelburg, J.J."'
Search Results
2. Influence of glacier type on bloom phenology in two Southwest Greenland fjords
- Author
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Stuart-Lee, A.E., primary, Mortensen, J., additional, Juul-Pedersen, T., additional, Middelburg, J.J., additional, Soetaert, K., additional, Hopwood, M.J., additional, Engel, A., additional, and Meire, L., additional
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- 2023
- Full Text
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3. A seasonal study of particulate organic matter composition and quality along an offshore transect in the southern North Sea
- Author
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Le Guitton, M., Soetaert, K., Sinninghe Damsté, J.S., and Middelburg, J.J.
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- 2017
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4. Carbon-13 labelling shows no effect of ocean acidification on carbon transfer in Mediterranean plankton communities
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Maugendre, L., Gattuso, J.-P., de Kluijver, A., Soetaert, K., van Oevelen, D., Middelburg, J.J., and Gazeau, F.
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- 2017
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5. Influence of glacier type on bloom phenology in two Southwest Greenland fjords
- Author
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Stuart-Lee, A. E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.J., Soetaert, K., Hopwood, M. J., Engel, Anja, Meire, L., Stuart-Lee, A. E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.J., Soetaert, K., Hopwood, M. J., Engel, Anja, and Meire, L.
- Abstract
Highlights: • Higher representation of picophytoplankton in land-terminating glacier fjord. • Smaller phytoplankton cells associated with glacial retreat. • Intermediate baroclinic circulation influences phytoplankton distribution. • Glacial retreat likely to have major implications for summer productivity. Abstract: Along Greenland's coastline, the magnitude and timing of primary production in fjords is influenced by meltwater release from marine-terminating glaciers. How local ecosystems will adapt as these glaciers retreat onto land, forcing fundamental changes in hydrography, remains an open question. To further our understanding of this transition, we examine how marine- and land-terminating glaciers respectively influence fjord bloom phenology. Between spring and autumn 2019, we conducted along-fjord transects of hydrographic variables, biogeochemical properties and pico- and nanophytoplankton counts to illustrate the contrasting seasonal bloom dynamics in the fjords Nuup Kangerlua and Ameralik. These fjords are in the same climatic region of west Greenland but influenced by different glacial structures. Nuup Kangerlua, a predominantly marine-terminating system, was differentiated by its sustained second summer bloom and high Chl a fluorescence in summer and autumn. In Ameralik, influenced by a land-terminating glacier, we found higher abundances of pico- and nanophytoplankton, and high cyanobacteria growth in autumn. The summer bloom in Nuup Kangerlua is known to be coincident with subglacial freshwater discharge sustaining renewed nutrient supply to the fjord. We observe here that the intermediate baroclinic circulation, which creates an inflow at subsurface depths, also plays an important role in increasing nutrient availability at shallower depths and potentially explains the distribution of primary producers. Our observations suggest that the retreat of marine-terminating glaciers onto land, with consequent increases in surface water temperature and strat
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- 2023
- Full Text
- View/download PDF
6. Influence of glacier type on bloom phenology in two Southwest Greenland fjords
- Author
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Geochemistry, Stuart-Lee, A.E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.j., Soetaert, K., Hopwood, M.j., Engel, A., Meire, L., Geochemistry, Stuart-Lee, A.E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.j., Soetaert, K., Hopwood, M.j., Engel, A., and Meire, L.
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- 2023
7. Influence of glacier type on bloom phenology in two Southwest Greenland fjords
- Author
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Stuart-Lee, A.E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.J., Soetaert, K., Hopwood, M.J., Engel, A., Meire, L., Stuart-Lee, A.E., Mortensen, J., Juul-Pedersen, T., Middelburg, J.J., Soetaert, K., Hopwood, M.J., Engel, A., and Meire, L.
- Abstract
Along Greenland's coastline, the magnitude and timing of primary production in fjords is influenced by meltwater release from marine-terminating glaciers. How local ecosystems will adapt as these glaciers retreat onto land, forcing fundamental changes in hydrography, remains an open question. To further our understanding of this transition, we examine how marine- and land-terminating glaciers respectively influence fjord bloom phenology. Between spring and autumn 2019, we conducted along-fjord transects of hydrographic variables, biogeochemical properties and pico- and nanophytoplankton counts to illustrate the contrasting seasonal bloom dynamics in the fjords Nuup Kangerlua and Ameralik. These fjords are in the same climatic region of west Greenland but influenced by different glacial structures. Nuup Kangerlua, a predominantly marine-terminating system, was differentiated by its sustained second summer bloom and high Chl a fluorescence in summer and autumn. In Ameralik, influenced by a land-terminating glacier, we found higher abundances of pico- and nanophytoplankton, and high cyanobacteria growth in autumn. The summer bloom in Nuup Kangerlua is known to be coincident with subglacial freshwater discharge sustaining renewed nutrient supply to the fjord. We observe here that the intermediate baroclinic circulation, which creates an inflow at subsurface depths, also plays an important role in increasing nutrient availability at shallower depths and potentially explains the distribution of primary producers. Our observations suggest that the retreat of marine-terminating glaciers onto land, with consequent increases in surface water temperature and stratification, and reduced light availability, may alter the magnitude, composition, and distribution of summer productivity.
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- 2023
8. Deoxygenation and organic carbon sequestration in the Tethyan realm associated with the middle Eocene climatic optimum
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Cramwinckel, M.J., van der Ploeg, R., van Helmond, N.A.G.M., Waarlo, N., Agnini, C., Bijl, P.K., van der Boon, A., Brinkhuis, H., Frieling, J., Krijgsman, W., Mather, T.A., Middelburg, J.J., Peterse, F., Slomp, C.P., Sluijs, A., Cramwinckel, M.J., van der Ploeg, R., van Helmond, N.A.G.M., Waarlo, N., Agnini, C., Bijl, P.K., van der Boon, A., Brinkhuis, H., Frieling, J., Krijgsman, W., Mather, T.A., Middelburg, J.J., Peterse, F., Slomp, C.P., and Sluijs, A.
- Abstract
The middle Eocene climatic optimum (ca. 40 Ma) stands out as a transient global warming phase of ∼400 k.y. duration that interrupted long-termEocene cooling; it has been associated with a rise in atmospheric CO 2 concentrations that has been linked to a flare-up in Arabia-Eurasia continental arc volcanism. Increased organic carbon burial in the Tethys Ocean has been proposed as a carbon sequestration mechanism to bring the middle Eocene climatic optimum to an end. To further test these hypotheses, we assessed the sedimentary and geochemical expression of the middle Eocene climatic optimum in the northern Peri-Tethys, specifically, the organic-rich Kuma Formation of the Belaya River section, located on the edge of the Scythian Platform in the North Caucasus, Russia. We constructed an age-depth model using nannofossil chronobiostratigraphy. Throughout the studied middle Eocene interval (41.2−39.9 Ma), we documented sea-surface temperatures of 32−36 °C based on the tetraether index of tetraethers consisting of 86 carbons (TEX86), depending on proxy calibration, and during the early middle Eocene climatic optimum, we observed sea-surface warming of 2−3 °C. Despite the proximity of the section to the Arabia-Eurasia volcanic arc, the hypothesized source of volcanic CO2, we found no evidence for enhanced regional volcanism in sedimentary mercury concentrations. Sedimentary trace-element concentrations and iron speciation indicate reducing bottom waters throughout the middle Eocene, but the most reducing, even euxinic, conditions were reached during late middle Eocene climatic optimum cooling. This apparent regional decoupling between ocean warming and deoxygenation hints at a role for regional tectonics in causing basin restriction and anoxia. Associated excess organic carbon burial, extrapolated to the entire regional Kuma Formation, may have been ∼8.1 Tg C yr−1, comprising ∼450 Pg C over this ∼55 k.y. interval. Combined wit
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- 2023
9. Inland Waters Increasingly Produce and Emit Nitrous Oxide
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Bio-, hydro-, and environmental geochemistry, Geochemistry, Wang, Junjie, Vilmin, Lauriane, Mogollón, José Manuel, Beusen, Arthur, van Hoek, Wim J., Liu, Xiaochen, Pika, Philip A., Middelburg, J.J., Bouwman, Alexander F., Bio-, hydro-, and environmental geochemistry, Geochemistry, Wang, Junjie, Vilmin, Lauriane, Mogollón, José Manuel, Beusen, Arthur, van Hoek, Wim J., Liu, Xiaochen, Pika, Philip A., Middelburg, J.J., and Bouwman, Alexander F.
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- 2023
10. Diet shifts and population dynamics of estuarine foraminifera during ecosystem recovery after experimentally induced hypoxia crises
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Brouwer, G.M., Duijnstee, I.A.P., Hazeleger, J.H., Rossi, F., Lourens, L.J., Middelburg, J.J., and Wolthers, M.
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- 2016
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11. Biogeochemical consequences of vertical and lateral transport of particulate organic matter in the southern North Sea: A multiproxy approach
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Le Guitton, M., Soetaert, K., Damsté, J.S. Sinninghe, and Middelburg, J.J.
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- 2015
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12. Effects of climate change and nutrient concentrations on carbon sources for zooplankton in a Tibetan Plateau lake over the past millennium
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Su, Y., Li, K., Zhang, Y., Liu, Z., Wang, T., Jeppesen, E., Middelburg, J.J., Smol, J.P., Geochemistry, General geochemistry, Geochemistry, and General geochemistry
- Subjects
Carbon source ,Climate change ,Cladoceran subfossils ,Nutrients ,Aquatic Science ,Earth-Surface Processes - Abstract
Autochthonous and allochthonous organic carbon (OC) are important carbon sources for zooplankton in lakes, and changes in the abundance and proportions of those sources may affect zooplankton community composition and lake ecosystem function. Nevertheless, long-term changes in assimilation of autochthonous and allochthonous carbon by zooplankton and associated climate- and environment-related forcing mechanisms have rarely been studied. We used a sediment record of cladoceran remains and geochemical variables from Lake Jirentso on the Tibetan Plateau to track long-term changes in sources of carbon for cladocera over the past ~ 950 years. High cladoceran:diatom accumulation rate ratios during the cold Little Ice Age indicated that cladocerans assimilated more allochthonous OC that was released from glaciers and frozen soils to replenish their food supply, a consequence of low primary production in the lake. In contrast, low cladoceran:diatom accumulation rate ratios during the Current Warm Period indicated that cladocerans utilized more autochthonous OC. Less autochthonous OC was available for cladocerans during the Medieval Warm Period than during the Current Warm Period. The total accumulation rate of cladocerans was significantly correlated with the annual mean air temperature, total phosphorus, and the organic carbon to nitrogen ratio in the sediment core. Recent warming and sharply increased nutrient inputs affected the cladoceran and diatom assemblages, further inducing a shift in the diet of zooplankton towards more recently produced OC. The sediment record from Lake Jirentso, which represents the last ~ 950 years of deposition, spanned an ideal time window for assessing historical changes related to the impacts of climate and nutrients on zooplankton carbon sources.
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- 2022
13. Global estimates of the extent and production of macroalgal forests
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Duarte, C.M., Gattuso, J.-P., Hancke, K., Gundersen, H., Filbee-Dexter, K., Pedersen, M.F., Middelburg, J.J., Burrows, M., Krumhansl, K.A., Wernberg, T., Moore, P., Pessarrodona, A., Ørberg, S.B., Pinto, I.S., Assis, J., Queirós, A., Smale, D.A., Bekkby, T., Serrão, E., Krause-Jensen, D., Geochemistry, Bio-, hydro-, and environmental geochemistry, Geochemistry, and Bio-, hydro-, and environmental geochemistry
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macroalgae ,seaweeds ,trends ,Global and Planetary Change ,niche ,Ecology ,biome ,area ,production ,Ecology, Evolution, Behavior and Systematics - Abstract
Aim Macroalgal habitats are believed to be the most extensive and productive of all coastal vegetated ecosystems. In stark contrast to the growing attention on their contribution to carbon export and sequestration, understanding of their global extent and production is limited and these have remained poorly assessed for decades. Here we report a first data-driven assessment of the global extent and production of macroalgal habitats based on modelled and observed distributions and net primary production (NPP) across habitat types. Location Global coastal ocean. Time period Contemporary. Major taxa studied Macroalgae. Methods Here we apply a comprehensive niche model to generate an improved global map of potential macroalgal distribution, constrained by incident light on the seafloor and substrate type. We compiled areal net primary production (NPP) rates across macroalgal habitats from the literature and combined this with our estimates of the global extent of these habitats to calculate global macroalgal NPP. Results We show that macroalgal forests are a major biome with a global area of 6.06-7.22 million km(2), dominated by red algae, and NPP of 1.32 Pg C/year, dominated by brown algae. Main conclusions The global macroalgal biome is comparable, in area and NPP, to the Amazon forest, but is globally distributed as a thin strip around shorelines. Macroalgae are expanding in polar, subpolar and tropical areas, where their potential extent is also largest, likely increasing the overall contribution of algal forests to global carbon sequestration. info:eu-repo/semantics/publishedVersion
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- 2022
14. Quantifying the degradation of organic matter in marine sediments: A review and synthesis
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Arndt, Sandra, Jørgensen, B.B., LaRowe, D.E., Middelburg, J.J., Pancost, R.D., and Regnier, P.
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- 2013
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15. Polyphosphate Dynamics in Cable Bacteria
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Geerlings, N.M.J., Kienhuis, M.V.M., Hidalgo-Martinez, S., Hageman, R., Vasquez-Cardenas, D., Middelburg, J.J., Meysman, F.J.R., Polerecky, L., Geochemistry, GeoLab Algemeen, Bio-, hydro-, and environmental geochemistry, Geochemistry, GeoLab Algemeen, and Bio-, hydro-, and environmental geochemistry
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Microbiology (medical) ,cable bacteria ,cell cycle ,polyphosphate ,Microbiology ,Biology ,Engineering sciences. Technology ,stable isotope probing ,nanoSIMS - Abstract
Cable bacteria are multicellular sulfide oxidizing bacteria that display a unique metabolism based on long-distance electron transport. Cells in deeper sediment layers perform the sulfide oxidizing half-reaction whereas cells in the surface layers of the sediment perform the oxygen-reducing half-reaction. These half-reactions are coupled via electron transport through a conductive fiber network that runs along the shared cell envelope. Remarkably, only the sulfide oxidizing half-reaction is coupled to biosynthesis and growth whereas the oxygen reducing half-reaction serves to rapidly remove electrons from the conductive fiber network and is not coupled to energy generation and growth. Cells residing in the oxic zone are believed to (temporarily) rely on storage compounds of which polyphosphate (poly-P) is prominently present in cable bacteria. Here we investigate the role of poly-P in the metabolism of cable bacteria within the different redox environments. To this end, we combined nanoscale secondary ion mass spectrometry with dual-stable isotope probing (13C-DIC and 18O-H2O) to visualize the relationship between growth in the cytoplasm (13C-enrichment) and poly-P activity (18O-enrichment). We found that poly-P was synthesized in almost all cells, as indicated by 18O enrichment of poly-P granules. Hence, poly-P must have an important function in the metabolism of cable bacteria. Within the oxic zone of the sediment, where little growth is observed, 18O enrichment in poly-P granules was significantly lower than in the suboxic zone. Thus, both growth and poly-P metabolism appear to be correlated to the redox environment. However, the poly-P metabolism is not coupled to growth in cable bacteria, as many filaments from the suboxic zone showed poly-P activity but did not grow. We hypothesize that within the oxic zone, poly-P is used to protect the cells against oxidative stress and/or as a resource to support motility, while within the suboxic zone, poly-P is involved in the metabolic regulation before cells enter a non-growing stage.
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- 2022
16. High precipitation rates characterize biomineralization in the benthic foraminifer Ammonia beccarii
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Geerken, E., de Nooijer, L.J., Toyofuku, T., Roepert, A., Middelburg, J.J., Kienhuis, M.V.M., Nagai, Y., Polerecky, L., Reichart, G.-J., Geerken, E., de Nooijer, L.J., Toyofuku, T., Roepert, A., Middelburg, J.J., Kienhuis, M.V.M., Nagai, Y., Polerecky, L., and Reichart, G.-J.
- Abstract
The chemical composition of foraminiferal calcite reflects seawater variables and is therefore a popular paleoceanographic tool. The sedimentary record of foraminiferal shell chemistry is, however, mostly interpreted using empirical calibrations. Since geochemical patterns in foraminifera often deviate from inorganic analogues, there is an ongoing need for a more mechanistic understanding of foraminiferal biomineralization . One of the most elusive, but potentially important parameters characterizing foraminiferal biomineralization is the rate of calcite precipitation. Using a combination of labelling experiments and sub-micrometer imaging of the incorporated label with NanoSIMS , we show that the benthic foraminifer Ammonia beccarii precipitates its calcite at a rate of ∼24 ± 4 nmol/cm2/min. These values are close to maximum reported rates for inorganic calcite precipitation from Mg-depleted seawater, which is consistent with the strong fractionation against Mg during biomineralization. At the same time, the measured precipitation rate is in accordance with the similarity between the foraminiferal Sr/Ca values and ratios from calcite precipitated inorganically at these rates. Our results also show that the
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- 2022
17. Polyphosphate Dynamics in Cable Bacteria
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Geochemistry, GeoLab Algemeen, Bio-, hydro-, and environmental geochemistry, Geerlings, N.M.J., Kienhuis, M.V.M., Hidalgo-Martinez, S., Hageman, R., Vasquez-Cardenas, D., Middelburg, J.J., Meysman, F.J.R., Polerecky, L., Geochemistry, GeoLab Algemeen, Bio-, hydro-, and environmental geochemistry, Geerlings, N.M.J., Kienhuis, M.V.M., Hidalgo-Martinez, S., Hageman, R., Vasquez-Cardenas, D., Middelburg, J.J., Meysman, F.J.R., and Polerecky, L.
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- 2022
18. RADIv1: a non-steady-state early diagenetic model for ocean sediments in Julia and MATLAB/GNU Octave
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Geochemistry, Bio-, hydro-, and environmental geochemistry, Sulpis, O., Humphreys, M.P., Wilhelmus, M.M., Carroll, D., Berelson, W.M., Menemenlis, D., Middelburg, J.J., Adkins, J.F., Geochemistry, Bio-, hydro-, and environmental geochemistry, Sulpis, O., Humphreys, M.P., Wilhelmus, M.M., Carroll, D., Berelson, W.M., Menemenlis, D., Middelburg, J.J., and Adkins, J.F.
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- 2022
19. Global estimates of the extent and production of macroalgal forests
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Geochemistry, Bio-, hydro-, and environmental geochemistry, Duarte, C.M., Gattuso, J.-P., Hancke, K., Gundersen, H., Filbee-Dexter, K., Pedersen, M.F., Middelburg, J.J., Burrows, M., Krumhansl, K.A., Wernberg, T., Moore, P., Pessarrodona, A., Ørberg, S.B., Pinto, I.S., Assis, J., Queirós, A., Smale, D.A., Bekkby, T., Serrão, E., Krause-Jensen, D., Geochemistry, Bio-, hydro-, and environmental geochemistry, Duarte, C.M., Gattuso, J.-P., Hancke, K., Gundersen, H., Filbee-Dexter, K., Pedersen, M.F., Middelburg, J.J., Burrows, M., Krumhansl, K.A., Wernberg, T., Moore, P., Pessarrodona, A., Ørberg, S.B., Pinto, I.S., Assis, J., Queirós, A., Smale, D.A., Bekkby, T., Serrão, E., and Krause-Jensen, D.
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- 2022
20. RADIv1: a non-steady-state early diagenetic model for ocean sediments in Julia and MATLAB/GNU Octave
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Sulpis, O., Humphreys, M.P., Wilhelmus, M.M., Carroll, D., Berelson, W.M., Menemenlis, D., Middelburg, J.J., Adkins, J.F., Sulpis, O., Humphreys, M.P., Wilhelmus, M.M., Carroll, D., Berelson, W.M., Menemenlis, D., Middelburg, J.J., and Adkins, J.F.
- Abstract
We introduce a time-dependent, one-dimensional model of early diagenesis that we term RADI, an acronym accounting for the main processes included in the model: chemical reactions, advection, molecular and bio-diffusion, and bio-irrigation. RADI is targeted for study of deep-sea sediments, in particular those containing calcium carbonates (CaCO3). RADI combines CaCO3 dissolution driven by organic matter degradation with a diffusive boundary layer and integrates state-of-the-art parameterizations of CaCO3 dissolution kinetics in seawater, thus serving as a link between mechanistic surface reaction modeling and global-scale biogeochemical models. RADI also includes CaCO3 precipitation, providing a continuum between CaCO3 dissolution and precipitation. RADI integrates components rather than individual chemical species for accessibility and is straightforward to compare against measurements. RADI is the first diagenetic model implemented in Julia, a high-performance programming language that is free and open source, and it is also available in MATLAB/GNU Octave. Here, we first describe the scientific background behind RADI and its implementations. Following this, we evaluate its performance in three selected locations and explore other potential applications, such as the influence of tides and seasonality on early diagenesis in the deep ocean. RADI is a powerful tool to study the time-transient and steady-state response of the sedimentary system to environmental perturbation, such as deep-sea mining, deoxygenation, or acidification events.
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- 2022
21. The important role of sponges in carbon and nitrogen cycling in a deep‐sea biological hotspot
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Hanz, U., Riekenberg, P.M., de Kluijver, A., van der Meer, M.T.J., Middelburg, J.J., de Goeij, J.M., Bart, M.C., Wurz, E., Colaço, A., Duineveld, G.C.A., Reichart, G.-J., Rapp, H.T., Mienis, F., Hanz, U., Riekenberg, P.M., de Kluijver, A., van der Meer, M.T.J., Middelburg, J.J., de Goeij, J.M., Bart, M.C., Wurz, E., Colaço, A., Duineveld, G.C.A., Reichart, G.-J., Rapp, H.T., and Mienis, F.
- Abstract
Deep-sea sponge grounds are hotspots of biodiversity, harboring thriving ecosystems in the otherwise barren deep sea. It remains unknown how these sponge grounds survive in this food-limited environment.2. Here, we unravel how sponges and their associated fauna sustain themselves by identifying their food sources and food-web interactions using bulk and compound-specific stable isotope analysis of amino and fatty acids.3. We found that sponges with a high microbial abundance had an isotopic composition resembling organisms at the base of the food web, suggesting that they are able to use dissolved resources that are generally inaccessible to animals. In contrast, low microbial abundance sponges had a bulk isotopic composition that resembles a predator at the top of a food web, which appears to be the result of very efficient recycling pathways that are so far unknown. The compound-specific-isotope analysis, however, positioned low-microbial abundance sponges with other filter-feeding fauna. Furthermore, fatty-acid analysis confirmed transfer of sponge-derived organic material to the otherwise food-limited associated fauna.4. Through this subsidy, sponges are key to the sustenance of thriving deep-sea ecosystems and might have, due to their ubiquitous abundance, a global impact on biogeochemical cycles.
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- 2022
22. The important role of sponges in carbon and nitrogen cycling in a deep-sea biological hotspot
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Geochemistry, Stratigraphy and paleontology, General geochemistry, Hanz, U., Riekenberg, P., de Kluijver, A., van der Meer, M., Middelburg, J.J., de Goeij, J.M., Bart, M.C., Wurz, E., Colaço, A., Duineveld, G.C.A., Reichart, G.-J., Rapp, H.-T., Mienis, F., Geochemistry, Stratigraphy and paleontology, General geochemistry, Hanz, U., Riekenberg, P., de Kluijver, A., van der Meer, M., Middelburg, J.J., de Goeij, J.M., Bart, M.C., Wurz, E., Colaço, A., Duineveld, G.C.A., Reichart, G.-J., Rapp, H.-T., and Mienis, F.
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- 2022
23. Effects of climate change and nutrient concentrations on carbon sources for zooplankton in a Tibetan Plateau lake over the past millennium
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Geochemistry, General geochemistry, Su, Y., Li, K., Zhang, Y., Liu, Z., Wang, T., Jeppesen, E., Middelburg, J.J., Smol, J.P., Geochemistry, General geochemistry, Su, Y., Li, K., Zhang, Y., Liu, Z., Wang, T., Jeppesen, E., Middelburg, J.J., and Smol, J.P.
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- 2022
24. Proton cycling, buffering, and reaction stoichiometry in natural waters
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Hofmann, A.F., Middelburg, J.J., Soetaert, K., A.Wolf-Gladrow, D., and Meysman, F.J.R.
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- 2010
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25. Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995–2005)
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Van Engeland, T., Soetaert, K., Knuijt, A., Laane, R.W.P.M., and Middelburg, J.J.
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- 2010
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26. Global River Sediments (GloRiSe)
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Müller, G., Middelburg, J.J. & Sluijs, A.
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- 2021
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27. An integrative model of carbon and nitrogen metabolism in a common deep-sea sponge (Geodia barretti)
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de Kluijver, A., Bart, M.C., van Oevelen, D., de Goeij, J.M., Leys, S.P., Maier, S.R., Maldonado, M., Soetaert, K., Verbiest, S., Middelburg, J.J., de Kluijver, A., Bart, M.C., van Oevelen, D., de Goeij, J.M., Leys, S.P., Maier, S.R., Maldonado, M., Soetaert, K., Verbiest, S., and Middelburg, J.J.
- Abstract
Deep-sea sponges and their microbial symbionts transform various forms of carbon (C) and nitrogen (N) via several metabolic pathways, which, for a large part, are poorly quantified. Previous flux studies on the common deep-sea sponge Geodia barretti consistently revealed net consumption of dissolved organic carbon (DOC) and oxygen (O2) and net release of nitrate (NO−3NO3-). Here we present a biogeochemical metabolic network model that, for the first time, quantifies C and N fluxes within the sponge holobiont in a consistent manner, including many poorly constrained metabolic conversions. Using two datasets covering a range of individual G. barretti sizes (10–3,500 ml), we found that thevariability in metabolic rates partially resulted from body size as O 2 uptake allometrically scales with sponge volume. Our model analysis confirmed that dissolved organic matter (DOM), with an estimated C:N ratio of 7.7 ± 1.4, is the main energy source of G. barretti. DOM is primarily used for aerobic respiration, then for dissimilatory NO−3NO3- reduction to ammonium (NH+4)NH4+) (DNRA), and, lastly, for denitrification. Dissolved organic carbon (DOC) production efficiencies (production/assimilation) were estimated as 24 ± 8% (larger individuals) and 31 ± 9% (smaller individuals), so most DOC was respired to carbon dioxide (CO2), which was released in a net ratio of 0.77–0.81 to O2 consumption. Internally produced NH+4NH4+ from cellular excretion and DNRA fueled nitrification. Nitrification-associated chemoautotrophic production contributed 5.1–6.7 ± 3.0% to total sponge production. While overall metabolic patterns were rather independent of sponge size, (volume-)specific rates were lower in larger sponges comparedto smaller individuals. Specific biomass production rates were 0.16% day–1 in smaller compared to 0.067% day–1 in larger G. barretti as expected for slow-growi
- Published
- 2021
28. Modeling process-based biogeochemical dynamics in surface freshwaters of large watersheds with the IMAGE-DGNM framework
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Vilmin, L., Mogollón, J.M., Beusen, A.H.W., van Hoek, W.J., Liu, X., Middelburg, J.J., Bouwman, A.F., Bio-, hydro-, and environmental geochemistry, and Geochemistry
- Abstract
Over the last centuries, human activities have exerted increasing pressures on the environment, leading to drastic alterations in the functioning of freshwater bodies (e.g., eutrophication). Global biogeochemical models have proven crucial to investigate interactions between humans, hydrology, and water quality of surface fresh waters. However, most do not account for high‐resolution spatial and temporal variability within watersheds, and they typically lack any representation of benthic dynamics that can drive pollution legacy effects. We present here the Integrated Model to Assess the Global Environment‐Dynamic Global Nutrient Model (IMAGE‐DGNM), which couples global, spatially explicit hydrology and integrated assessment models with process‐based biogeochemistry in surface fresh waters. The new Dynamic In‐Stream Chemistry (DISC) module calculates advective transport from headwaters to estuaries, processes in the water column and in bed sediments, as well as the exchanges between these two compartments. As application examples of IMAGE‐DGNM, we simulate sediment dynamics and nitrogen cycling in two large river basins. We assess in‐stream concentration time series at specific locations, and identify governing processes in transfers along the aquatic continuum. Results highlight the importance of benthic dynamics in watersheds highly perturbed by damming. The implementation of such dynamics within IMAGE‐DGNM allows for including the temporal effect of pollution legacies in large scale water quality studies and shifts in pollutant speciation along river continua. This new framework therefore incorporates new features for large basin to global scale studies that are crucial to better predict the effects on receiving ecosystems and evaluate future environmental management pathways.
- Published
- 2020
29. Impacts of atmospheric anthropogenic nitrogen on the open ocean
- Author
-
Duce, R.A., LaRoche, J., Altieri, K., Arrigo, K.R., Baker, A.R., Capone, D.G., Cornell, S., Dentener, F., Galloway, J., Ganeshram, R.S., Geider, R.J., Jickells, T., Kuypers, M.M., Langlois, R., Liss, P.S., Liu, S.M., Middelburg, J.J., Moore, C.M., Nickovic, S., Oschlies, A., Pedersen, T., Prospero, J., Schlitzer, R., Seitzinger, S., Sorensen, L.L., Uematsu, M., Ulloa, O., Voss, M., Ward, B., and Zamora, L.
- Subjects
Ocean -- Chemical properties ,Nitrogen -- Research - Published
- 2008
30. Modeling process-based biogeochemical dynamics in surface freshwaters of large watersheds with the IMAGE-DGNM framework
- Author
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Bio-, hydro-, and environmental geochemistry, Geochemistry, Vilmin, L., Mogollón, J.M., Beusen, A.H.W., van Hoek, W.J., Liu, X., Middelburg, J.J., Bouwman, A.F., Bio-, hydro-, and environmental geochemistry, Geochemistry, Vilmin, L., Mogollón, J.M., Beusen, A.H.W., van Hoek, W.J., Liu, X., Middelburg, J.J., and Bouwman, A.F.
- Published
- 2020
31. Paratethys pacing of the Messinian Salinity Crisis: Low salinity waters contributing to gypsum precipitation?
- Author
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Grothe, A., Andreetto, F., Reichart, G.-J., Wolthers, M., Van Baak, C.G.C., Vasiliev, I., Stoica, M., Sangiorgi, F., Middelburg, J.J., Davies, G.R., Krijgsman, W., Grothe, A., Andreetto, F., Reichart, G.-J., Wolthers, M., Van Baak, C.G.C., Vasiliev, I., Stoica, M., Sangiorgi, F., Middelburg, J.J., Davies, G.R., and Krijgsman, W.
- Abstract
During the so-called Messinian Salinity Crisis (MSC: 5.97-5.33 Myr ago), reduced exchange with the Atlantic Ocean caused the Mediterranean to develop into a “saline giant” wherein ∼1 million km3 of evaporites (gypsum and halite) were deposited. Despite decades of research it is still poorly understood exactly how and where in the water column these evaporites formed. Gypsum formation commonly requires enhanced dry conditions (evaporation exceeding precipitation), but recent studies also suggested major freshwater inputs into the Mediterranean during MSC-gypsum formation. Here we use strontium isotope ratios of ostracods to show that low-saline water from the Paratethys Seas actually contributed to the precipitation of Mediterranean evaporites. This apparent paradox urges for an alternative mechanism underlying gypsum precipitation. We propose that Paratethys inflow would enhance stratification in the Mediterranean and result in a low-salinity surface-water layer with high Ca/Cl and SO4/Cl ratios. We show that evaporation of this surface water can become saturated in gypsum at a salinity of ∼40, in line with salinities reported from fluid inclusions in MSC evaporites.
- Published
- 2020
32. Understanding alkalinity to quantify ocean buffering
- Author
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Middelburg, J.J., Soetaert, Karline, Hagens, Mathilde, Middelburg, J.J., Soetaert, Karline, and Hagens, Mathilde
- Abstract
Ocean alkalinity plays a major role in ocean’s carbon uptake, in buffering, and in calcium carbonate production and dissolution, and it impacts and is affected by various biogeochemical processes.
- Published
- 2020
33. Ocean alkalinity, buffering and biogeochemical processes
- Author
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Middelburg, J.J., Soetaert, Karline, Hagens, Mathilde, Middelburg, J.J., Soetaert, Karline, and Hagens, Mathilde
- Abstract
Alkalinity, the excess of proton acceptors over donors, plays a major role in ocean chemistry, in buffering and in calcium carbonate precipitation and dissolution. Understanding alkalinity dynamics is pivotal to quantify ocean carbon dioxide uptake during times of global change. Here we review ocean alkalinity and its role in ocean buffering as well as the biogeochemical processes governing alkalinity and pH in the ocean. We show that it is important to distinguish between measurable titration alkalinity and charge balance alkalinity that is used to quantify calcification and carbonate dissolution and needed to understand the impact of biogeochemical processes on components of the carbon dioxide system. A general treatment of ocean buffering and quantification via sensitivity factors is presented and used to link existing buffer and sensitivity factors. The impact of individual biogeochemical processes on ocean alkalinity and pH is discussed and quantified using these sensitivity factors. Processes governing ocean alkalinity on longer time scales such as carbonate compensation, (reversed) silicate weathering, and anaerobic mineralization are discussed and used to derive a close‐to‐balance ocean alkalinity budget for the modern ocean.
- Published
- 2020
34. Biomarker and carbon isotopic constraints on bacterial and algal community structure and functioning in a turbid, tidal estuary
- Author
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Boschker, H.T.S., Kromkamp, J.C., and Middelburg, J.J.
- Subjects
Isotopes -- Analysis ,Planktonic bacteria -- Genetic aspects ,Earth sciences - Abstract
We studied planktonic community structure and isotopic composition using compound-specific [sup.13]C analysis of phospholipid-derived fatty acids (PLFA) along the Scheldt estuary during a spring bloom. A comprehensive set of other carbon cycle parameters was also determined. Based on dissolved carbon dioxide and oxygen concentrations and primary and bacterial secondary production, the trophic status of the estuary changed from strongly net heterotrophic in the upper to net autotrophic in the lower estuary. Concentrations of algal PLFA and pigments and microscopic identifications of dominant phytoplankton revealed the same trend: a mixed community of green algae and diatoms dominated the freshwater phytoplankton and there was a major diatom bloom at intermediate salinities. Bacterial biomass (also based on PLFA) was much lower for the diatom bloom in the lower estuary than in the net heterotrophic upper estuary. Carbon isotopic ratios of the main diatom marker PLFA. 20: 5[omega]3, were mainly related to changes in [[dealta.sup.13]C values of dissolved inorganic carbon and showed a residual variation of ~5 [per thousand], which is probably related to changes in growth conditions along the estuary. The green algal marker 18: 3[omega]3 was much more depleted in [sup.13]C than the diatom markers, suggesting that these two main pbytoplankton groups use a different inorganic carbon source or carbon dioxide fixation mechanism. Isotopic ratios of the different bacterial PLFA detected were very similar and ranged between -30 [per thousand] and -21 [per thousand]. They closely tracked [[delta].sup.13]C values in particulate organic carbon (POC), indicating that POC or material with the same [sup.13]C signature was the main bacterial carbon substrate. In the lower, marine side of the estuary, isotope ratios of bacterial and algal PLFA were similar, suggesting a coupling between primary production and bacterial consumption of organic matter. However. [[delta].sup.13]C values of bacterial PLFA in the upper estuary were enriched compared with algal PLFA t between 6 [per thousand] and 15 [per thousand]), indicating an uncoupled algal-bacterial system with allochthonous subsidies, such as terrestrial C3 organic matter or sewage supporting bacterial growth.
- Published
- 2005
35. Interspecific and intraspecific variation of [delta][sup.13]C and [delta][sup.15]N in deposit- and suspension-feeding bivalves (Macoma balthica and Cerastoderma edule): evidence of ontogenetic changes in feeding mode of Macoma balthica
- Author
-
Rossi, F., Herman, P.M.J., and Middelburg, J.J.
- Subjects
Earth sciences - Abstract
Deposit and suspension feeders can switch feeding behavior and show variations in feeding mode as individuals pass through life-cycle stages. Stable carbon and nitrogen isotopes were used to trace changes in diet of the tellinid bivalves M. balthica (facultative deposit feeder) and C. edule (obligatory suspension feeder), according to their size class. Analyses of variance showed differences in the [[delta].sup.13]C between the species. C. edule showed a diet composed of microphytoplankton, whereas M. balthica could feed on a mixed diet of microalgae from benthos and plankton. Values of [[delta].sup.13]C depended significantly on body size in M. balthica, providing evidence of ontogenetic variation in diet with small juveniles feeding entirely on microphytobenthos, while there was a gradual tendency for larger sizes to feed more on microphytoplankton. Therefore, although these species rely on different sources of food, large animals of M. balthica can overlap the trophic niche of C. edule. Population dynamics of the animals should be considered in food-web studies.
- Published
- 2004
36. Biogeochemistry, An Introduction
- Author
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Laane, R.W.P.M., primary and Middelburg, J.J., additional
- Published
- 2011
- Full Text
- View/download PDF
37. Functioning of Ecosystems at the Land–Ocean Interface
- Author
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Heip, C.H.R., primary, Middelburg, J.J., additional, and Philippart, C.J.M., additional
- Published
- 2011
- Full Text
- View/download PDF
38. Microbial carbon processing in oligotrophic Lake Lucerne (Switzerland): results of in situ 13C-labelling studies
- Author
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Lammers, J.M., Schubert, C.J., Middelburg, J.J., Reichart, G.J., Geochemistry, Stratigraphy and paleontology, and General geochemistry
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,01 natural sciences ,Carbon cycle ,Water column ,parasitic diseases ,Phytoplankton ,Phytoplanktonbacteria coupling ,Environmental Chemistry ,Photic zone ,Organic matter ,Trophic state index ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,2. Zero hunger ,Total organic carbon ,chemistry.chemical_classification ,Ecology ,010604 marine biology & hydrobiology ,15. Life on land ,Plankton ,6. Clean water ,Lacustrine food-web ,chemistry ,13. Climate action ,Environmental chemistry ,Environmental science ,d13C tracer ,Biomarkers - Abstract
Although lakes play a major role in the storage of organic carbon, processes involved are not yet very well characterized, especially for oligotrophic lakes. Whether a lake functions as a net source or sink for carbon depends on relative rates of primary production, inputs of terrestrial organic matter and respiration. The microbial community will affect the efficiency of carbon cycling and thereby potential carbon storage. Because the organic matter fluxes are smaller in oligotrophic lakes they have been studied less intensively with respect to their carbon cycling compared to eutrophic lakes. Whether they play an appreciable role in freshwater carbon cycling relies on unraveling primary and secondary production. Here we present the results from such a study in oligotrophic Lake Lucerne, Switzerland. Based on in situ carbon isotopic labelling experiments using dark, glucose-labelled and transparent, DIC-labelled bottles positioned at different depths in the water column, we conclude that even though the photic zone was very deep, integrated primary productivity was consistently low. The carbon processing efficiency of the heterotrophic producers was such that photosynthesized organic matter was fully consumed, even during times of maximum productivity. This implies that the heterotrophic producers were well adapted to rapidly respond to a temporary increase in primary productivity, which is in line with calculated bacterial growth efficiencies in the surface water layer. Highest glucose-based productivity, as a measure of the heterotrophic potential, was observed in the deepest parts of the water column. Chemoautotrophy was shown at 60 m water depth and is of relatively minor importance for overall fluxes. Mixotrophy was recognized as a strategy to keep up production when light conditions become less favorable for autotrophic growth. A mesocosm experiment earlier in the year indicated lower primary production, which agrees well with the timing of this experiment preceding the annual spring bloom. During the low-productivity season the coupling between phytoplankton and bacterial production was much weaker and potentially more organic matter could escape recycling at that time, although quantitatively fluxes remained very low.
- Published
- 2017
39. Role of carbonate burial in 'Blue Carbon' budgets
- Author
-
Saderne, V., Macreadle, P.I., Maher, D.T., Middelburg, J.J., Serrano, O., Almahasheer, H., Arias-Ortiz, A., Cusack, M., Eyre, B.D., Fourqurean, J., Kennedy, H., Krause-Jensen, Dorte, Kuwae, T., Lavery, Paul, Lovelock, C.E., Marbá, N., Masqué, Pere, Mateo, M.A., Mazarrasa, Inés, McGlathery, K., Oreska, M.P.J., Sanders, C.J., Santos, I.R., Smoak, J.M., Tanaya, T., Watanabe, K., and Duarte, C.M.
- Published
- 2019
40. Assimilation of ancient organic carbon by zoöplankton in Tibetan Plateau lakes is depending on watershed characteristics
- Author
-
Su, Y., Hu, E., Liu, Z., Jeppesen, E., Middelburg, J.J., Geochemistry, Bio-, hydro-, and environmental geochemistry, Geochemistry, and Bio-, hydro-, and environmental geochemistry
- Subjects
Biogeochemical cycle ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Aquatic ecosystem ,Drainage basin ,Glacier ,Aquatic Science ,010502 geochemistry & geophysics ,Oceanography ,Permafrost ,01 natural sciences ,Zooplankton ,Total inorganic carbon ,Phytoplankton ,Environmental science ,0105 earth and related environmental sciences - Abstract
Ancient (i.e., radiocarbon depleted) organic carbon (OC) is exported from ice sheet, glacier, and permafrost systems and may be buried, respired, or assimilated in downstream aquatic systems. Few studies have explored the potential use of this ancient OC in lake food webs. We combined natural abundance radiocarbon and stable carbon isotope data (Δ14C and δ13C) to study ancient OC utilization by zooplankton in six lakes covering a large climate gradient on the central and peripheral Tibetan Plateau. A depleted Δ14C signature of dissolved and particulate OC was found in the inflowing streams and lakes, ranging from – 49‰ to – 569‰, corresponding to radiocarbon ages between 403 yr and 6757 yr. The Δ14C values for zooplankton in the lakes ranged from – 45‰ to – 264‰, reflecting that zooplankton obtain 14C‐depleted signatures through assimilation of ancient OC and/or indirectly through consumption of phytoplankton or aquatic plant utilizing 14C‐depleted inorganic carbon. Moreover, ancient OC from inflowing streams contributed more to zooplankton diets in the temperate glacier area than in the cold glacier area. Assimilation of ancient OC by zooplankton in lakes is not only affected by drainage basin characteristics, such as the recharge coefficient of the lake, but also by the biogeochemical properties of OC. Use of ancient OC by zooplankton in high‐altitude lakes may constitute an important link between the contemporary aquatic food webs and the glaciated watersheds. Our findings have important implications for the contribution of ancient carbon to the modern lake food webs of high‐altitude and polar lakes.
- Published
- 2018
41. In the wake of darwin: using ab-initio continuum mechanics to describe the influence of macro-organisms on sediments
- Author
-
Meysman, F.J.R., primary, Middelburg, J.J., additional, Herman, P.M.J., additional, and Heip, C.H.R., additional
- Published
- 2002
- Full Text
- View/download PDF
42. Drivers of microbial carbon fluxes variability in two oligotrophic Mediterranean coastal systems
- Author
-
González-Benítez, N., García-Corral, L.S., Morán, X.A.G., Middelburg, J.J., Pizay, M.-D., Gattuso, J.P., González-Benítez, N., García-Corral, L.S., Morán, X.A.G., Middelburg, J.J., Pizay, M.-D., and Gattuso, J.P.
- Abstract
The carbon fluxes between phytoplankton and heterotrophic bacterioplankton were studied in two coastal oligotrophic sites in the NW Mediterranean. Phytoplankton and bacterial production rates were measured under natural conditions using different methods. In the Bay of Villefranche, the temporal variability revealed net heterotrophy in July-October and net autotrophy in December-March. The spatial variability was studied in the Bay of Palma, showing net autotrophic areas in the west and heterotrophic areas in the east. On average bacterial respiration, represented 62% of the total community respiration. Bacterial growth efficiency (BGE) values were significantly higher in autotrophic conditions than in heterotrophic ones. During autotrophic periods, dissolved primary production (DPP) was enough to sustained bacterial metabolism, although it showed a positive correlation with organic carbon stock (DOC). Under heterotrophic conditions, DPP did not sustain bacterial metabolism but bacterial respiration correlated with DPP and bacterial production with DOC. Temperature affected positively, DOC, BGE, bacterial respiration and production when the trophic status was autotrophic. To summarize, the response of bacterial metabolism to temperature and carbon sources depends on the trophic status within these oligotrophic coastal systems.
- Published
- 2019
43. Harmful algae and export production collapse in the equatorial Atlantic during the zenith of Middle Eocene Climatic Optimum warmth
- Author
-
Cramwinckel, M.J., van der Ploeg, R., Bijl, P.K., Peterse, F, Bohaty, S.M., Röhl, U., Schouten, S., Middelburg, J.J., Sluijs, A., Cramwinckel, M.J., van der Ploeg, R., Bijl, P.K., Peterse, F, Bohaty, S.M., Röhl, U., Schouten, S., Middelburg, J.J., and Sluijs, A.
- Abstract
New palynological, sedimentological, and geochemical records spanning the Middle Eocene Climatic Optimum (MECO; ca. 40 Ma) in the equatorial Atlantic Ocean indicate that peak warming was associated with upper-ocean stratification, decreased export production, and possibly harmful algal blooms, followed by slight oxygen minimum zone expansion. Combining these findings with published MECO records suggests that export production collapse and benthos starvation during the zenith of MECO warmth were widespread in the Atlantic. Furthermore, comparison to records across the Paleocene-Eocene thermal maximum (ca. 56 Ma) at the same site suggests a similar system response to warming, but with different impact on benthic communities.
- Published
- 2019
44. Role of carbonate burial in Blue Carbon budgets
- Author
-
Bio-, hydro-, and environmental geochemistry, Geochemistry, Saderne, V., N.R., Geraldi, Macreadie, Peter I., Maher, Damien T., Middelburg, J.J., Serrano, O., Almahasheer, H., Arias-Ortiz, A., Cusack, M., Eyre, B.D., Fourqurean, J.W., Kennedy, H., Krause-Jensen, D., Kuwae, T., Lavery, P.S., Lovelock, C.E., Marba, N., Masqué, P., Mateo, M.A., Mazarrasa, I., McGlathery, K.J., Oreska, M.P.J., Sanders, C.J., Santos, I.R., Smoak, J.M., Tanaya, T., Watanabe, K., Duarte, C.M., Bio-, hydro-, and environmental geochemistry, Geochemistry, Saderne, V., N.R., Geraldi, Macreadie, Peter I., Maher, Damien T., Middelburg, J.J., Serrano, O., Almahasheer, H., Arias-Ortiz, A., Cusack, M., Eyre, B.D., Fourqurean, J.W., Kennedy, H., Krause-Jensen, D., Kuwae, T., Lavery, P.S., Lovelock, C.E., Marba, N., Masqué, P., Mateo, M.A., Mazarrasa, I., McGlathery, K.J., Oreska, M.P.J., Sanders, C.J., Santos, I.R., Smoak, J.M., Tanaya, T., Watanabe, K., and Duarte, C.M.
- Published
- 2019
45. Ecology of Estuarine Macrobenthos
- Author
-
Herman, P.M.J., primary, Middelburg, J.J., additional, Van De Koppel, J., additional, and Heip, C.H.R., additional
- Published
- 1999
- Full Text
- View/download PDF
46. Working group report Relations between scale, model approach and model parameters
- Author
-
Middelburg, J.J., primary, Liss, P.S., additional, Dentener, F.J., additional, Kaminski, T., additional, Kroeze, C., additional, Malingreau, J.-P., additional, Novák, M., additional, Panikov, N.S., additional, Plant, R., additional, Starink, M., additional, and Wanninkhof, R., additional
- Published
- 1999
- Full Text
- View/download PDF
47. Stable isotopes and biomarkers in microbial ecology
- Author
-
Boschker, H.T.S. and Middelburg, J.J.
- Published
- 2002
- Full Text
- View/download PDF
48. Seasonal variability in the abundance and stable carbon-isotopic composition of lipid biomarkers in suspended particulate matter from a stratified equatorial lake (Lake Chala, Kenya/Tanzania): Implications for the sedimentary record
- Author
-
van Bree, L.G.J., Peterse, F., van der Meer, M.T.J., Middelburg, J.J., Negash, A.M.D., De Crop, W., Cocquyt, Christine, Wieringa, J.J., Verschuren, Dirk, Sinninghe Damsté, J.S., Organic geochemistry, Geochemistry, Organic geochemistry & molecular biogeology, Organic geochemistry, Geochemistry, and Organic geochemistry & molecular biogeology
- Subjects
Archeology ,010504 meteorology & atmospheric sciences ,Aquatic biomarkers ,Limnology ,010502 geochemistry & geophysics ,01 natural sciences ,Water column ,Crater lake ,Epilimnion ,Phytoplankton ,medicine ,Paleolimnology ,Paleoclimatology ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Stable isotopes ,Global and Planetary Change ,δ13C ,fungi ,Biogeochemistry ,Geology ,Seasonality ,medicine.disease ,East Africa ,Organic geochemistry ,Oceanography ,Environmental science - Abstract
We studied the distribution and stable carbon-isotopic (δ13C) composition of various lipid biomarkers in suspended particulate matter (SPM) from the water column of Lake Chala, a permanently stratified crater lake in equatorial East Africa, to evaluate their capacity to reflect seasonality in water-column processes and associated changes in the lake's phytoplankton community. This lake has large seasonal variation in water-column dynamics (stratified during wet seasons and mixing during dry seasons) with associated phytoplankton succession. We analyzed lipid biomarkers in SPM collected monthly at 5 depths (0–80 m) from September 2013 to January 2015. Seasonal variation in total phytoplankton biovolume is strongly reflected in the concentration of phytadienes, a derivative of the general photosynthetic pigment chlorophyll. The wax and wane of several specific biomarker lipids between June and December 2014 reflect pronounced phytoplankton succession after deep mixing, starting with a long and sustained chlorophyte bloom (reflected by C23:1, C25:1 and Cn-alkenes, and C21 and C23n-alkanes), followed by a peak in diatoms between July and October (loliolide and isololiolide), and then eustigmatophytes (C30 and C32 1,15 diols) once stratification resumes in October. Peak abundance of the C19:1n-alkene during shallow mixing of the water column in January–February 2014 can be tentatively linked to the seasonal distribution of cyanobacteria. The concentration, seasonal variability, and low δ13C values of the C28 fatty acid in the SPM suggest that this biomarker is produced in the water column of Lake Chala instead of having the typically assumed vascular plant origin. The δ13C signature of particulate carbon and all aquatic biomarkers become increasingly more negative (by up to 16‰) during mixing-induced episodes of high productivity, whereas enrichment would be expected during such blooms. This reversed fractionation may be attributed to chemically enhanced diffusion, which generates depleted HCO3− under high pH (>9) conditions, as occur in the epilimnion of Lake Chala during periods of high productivity. The influence of this process can potentially explain previously observed 13C-depleted carbon signatures in the paleorecord of Lake Chala, and should be considered prior to paleorecord interpretation of organic-matter δ13C values derived (partially) from aquatic organisms in high-pH, i.e. alkaline, lakes
- Published
- 2018
49. Seasonal variability in phytoplankton stable carbon isotope ratios and bacterial carbon sources in a shallow Dutch lake
- Author
-
Lammers, J.M., Reichart, G.-J., Middelburg, J.J., Geochemistry, Stratigraphy and paleontology, Organic geochemistry, and Bio-, hydro-, and environmental geochemistry
- Subjects
fungi - Abstract
Ecosystem metabolism of lakes strongly depends on the relative importance of local vs. allochthonous carbon sources and on microbial food-web functioning and structure. Over the year ecosystem metabolism varies as a result of seasonal changes in environmental parameters such as nutrient levels, light, temperature, and variability in the food web. This is reflected in isotopic compositions of phytoplankton and bacteria. Here, we present the results of a 17-month study on carbon dynamics in two basins of Lake Naarden, The Netherlands. One basin was restored after anthropogenic eutrophication, whereas the other basin remained eutrophic. We analyzed natural stable carbon isotope abundances (δ13C) of dissolved inorganic carbon, dissolved organic carbon and macrophytes, and combined these data with compound-specific δ13C analyses of phospholipid-derived fatty acids, produced by phytoplankton and bacteria. Isotopic fractionation (ε) between phytoplankton biomass and CO2(aq) was similar for diatoms and other eukaryotic phytoplankton, and differences between sampling sites were small. Highest ε values were observed in winter with values of 23.5±0.6‰ for eukaryotic phytoplankton and 13.6±0.3‰ for cyanobacteria. Lowest ε values were observed in summer: 10.5±0.3‰ for eukaryotic phytoplankton and 2.7±0.1‰ for cyanobacteria. The annual range in δ13Cbact was between 6.9‰ and 8.2‰ for the restored and eutrophic basin, respectively, while this range was between 11.6‰ and 13.1‰ for phytoplankton in the restored and eutrophic basin, respectively. Correlations between δ13Cphyto and δ13Cbact were strong at both sites. During summer and fall, bacterial biomass derives mainly from locally produced organic matter, with minor allochthonous contributions. Conversely, during winter, bacterial dependence on allochthonous carbon was 39-77% at the restored site, and 17-46% at the eutrophic site. © 2017 Association for the Sciences of Limnology and Oceanography.
- Published
- 2017
50. A Model for Early Diagenetic Processes in Sediments of the Continental Shelf of the Black Sea
- Author
-
Wijsman, J.W.M., Herman, P.M.J., Middelburg, J.J., and Soetaert, K.
- Published
- 2002
- Full Text
- View/download PDF
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