Olaf Dellwig

Leibniz Institute for Baltic Sea Research | IOW · Marine Geology

The Black Sea repeatedly experienced major hydrographic changes during glacial-interglacial transitions, with alternating limnic and brackish stages. While the redox conditions during the present Holocene brackish period (since ∼. 9,000. yr. BP) have been intensively studied, the redox evolution during the last interglacial, the Eemian (∼. 128,000-...

The Marine Isotope Stage (MIS) 3 stands out due to its abrupt changes from cold and dry stadials to warm and humid interstadials, the so-called Dansgaard-Oeschger cycles that also affected temperature and rainfall in the Black Sea region. This study is based on a gravity core from the southeastern (SE) Black Sea that covers the last glacial lake st...

Recent investigations have revealed significant fractionation of 238U/235U between organic-rich sediments of anoxic marginal seas and seawater, indicating redox-dependent U isotope fractionation. This study explores the conditions controlling U isotope fractionation in selected modern anoxic basins (Baltic Sea: Landsort and Gotland Deeps and the Ky...

The seasonal dynamics of molybdenum (Mo) were studied in the water column of two tidal basins of the German Wadden Sea (Sylt-Rømø and Spiekeroog) between 2007 and 2011. In contrast to its conservative behaviour in the open ocean, both, losses of more than 50% of the usual concentration level of Mo in seawater and enrichments up to 20% were observed...

Sediment contamination and seawater warming are two major stressors to macrobenthos in estuaries. However, little is known about their combined effects on infaunal organisms. Here we investigated the responses of an estuarine polychaete Hediste diversicolor to metal-contaminated sediment and increased temperature. Ragworms were exposed to sediments...

The short sediment core EMB201/7-4 retrieved from the East Gotland Basin, central Baltic Sea, is explored here as a candidate to host the stratigraphical basis for the Anthropocene series and its equivalent Anthropocene epoch, still to be formalized in the Geological Time Scale. The core has been accurately dated back to 1840 CE using a well-establ...

The Baltic Sea receives substantial amounts of hazardous substances and nutrients, which accumulate for decades and persistently impair the Baltic ecosystems. With long half-lives and high solubility, anthropogenic uranium isotopes (²³⁶U and ²³³U) are ideal tracers to depict the ocean dynamics in the Baltic Sea and the associated impacts on the fat...

The reduction of manganese oxide with sulfide in aquatic redox-stratified systems was previously considered to be mainly chemical, but recent isolation of the Black Sea isolate Candidatus Sulfurimonas marisnigri strain SoZ1 suggests an important role for biological catalyzation. Here we provide evidence from laboratory experiments, field data, and...

Manganese (Mn) oxides preferentially adsorb isotopically light tungsten (W). The global deposition of Mn oxides in (hyp)oxic marine settings represents the most plausible reason for an open ocean stable W isotope composition (δ186/184W = +0.543 ± 0.046‰) that is distinctly heavier than the main input source of marine W, the upper continental crust...

Stable tungsten isotopes (δ186/184W) show great potential for tracing the cycling of materials among geological reservoirs. This work investigates the behavior of stable W isotopes on the Earth’s surface by presenting new δ186/184W data of granitic rocks, loess, river water, fluvial sediments, regolith, estuarine seawater, and marine sediments. The...

Link (expring on March 4th, 2022): https://authors.elsevier.com/a/1ePUpB8ccudKN Rock weathering and pedogenesis are fundamental processes for element mobility in terrestrial bio-geochemical cycles and for the regulation of primary productivity in adjacent coastal marine ecosystems. Here, soils developed from volcanic ash under extreme climate cond...

Terrestrial surface waters and submarine ground water discharge (SGD) act as a source of dissolved substances for coastal systems. Solute fluxes of SGD depend on the ground water composition and the water-solid-microbe interactions close to the sediment-water interface. Thus, this study aims to characterize and evaluate the hydrogeochemical gradien...

Sedimentary ancient DNA-based studies have been used to probe centuries of climate and environmental changes and how they affected cyanobacterial assemblages in temperate lakes. Due to cyanobacteria containing potential bloom-forming and toxin-producing taxa, their approximate reconstruction from sediments is crucial, especially in lakes lacking lo...

The deep basins of the Baltic Sea experienced dramatic climate- and eutrophication-induced redox changes between oxic and euxinic water column conditions. Irregularly appearing Major Baltic Inflows (MBI) carrying North Sea waters to the Baltic Sea are partly able to oxygenate euxinic bottom waters within several weeks. After an absence of ∼10 years...

The continental silicon (Si) cycle, including terrestrial and freshwater ecosystems (lakes, rivers, estuaries), acts as a filter and modulates the amount of Si transported to the oceans. In order to link the variation in the terrestrial Si cycle to aquatic ecosystems, knowledge on changes in vegetation cover, soil disturbance and the impact of huma...

Significant sedimentation of manganese (Mn) in form of manganese oxides (MnOx) and the subsequent formation of authigenic calcium-rich rhodochrosite (Mn(Ca)CO3) were observed in the seasonally stratified hard water Lake Stechlin in north-eastern Germany. This manganese enrichment was assumed to be associated with recent eutrophication of the former...

Significance Abrupt climate shifts in the Northern Hemisphere high latitudes during the last glacial propagate globally in a complex manner. Our understanding of this propagation is poor mainly due to cross-dating uncertainties between individual paleoclimate archives. We apply a record of the globally common ¹⁰ Be production rate variations to syn...

Understanding hemisphere‐wide millennial‐scale temperature variability during past glacials in response to ice sheet dynamics and orbital forcing is one of the key targets for Quaternary climate research. While an inland propagation of abrupt temperature changes into Eurasia from the North Atlantic realm during the last glacial (Weichselian) receiv...

Input of ZnO nanoparticles (nZnO) from multiple sources have raised concerns about the potential toxic effects on estuarine and coastal organisms. The toxicity of nZnO and its interaction with common abiotic stressors (such as elevated temperature) are not well understood in these organisms. Here, we examined the bioenergetics responses of the blue...

The concentrations of dissolved and particulate manganese (Mndiss and Mnpart) were studied in the Wadden Sea and adjacent estuaries to gain insights into spatial and regional differences, but also to assess the source function of the tidal basins for the open North Sea compared to river discharge. Ten transects across tidal basins of the southern a...

ZnO nanoparticles (nZnO) are released into the coastal environment from multiple sources, yet their toxicity to marine organisms is not well understood. We investigated the interactive effects of salinity (normal 15, low 5, and fluctuating 5-15) and nZnO (100 μg l-1) on innate immunity of the blue mussels Mytilus edulis from a brackish area of the...

Redox-sensitive trace metals and their isotopes have emerged as important tools that are used to reconstruct the redox-evolution of the ocean-atmosphere system. However, reliability of such reconstructions ultimately depends on a solid understanding of the proxies in the present-day oceanic system and their archival potential in sediments. This stu...

Phosphorus (P) is one of the major drivers of eutrophication in aquatic systems. Thus, knowledge of riverine P inputs into the Baltic Sea is essential to evaluate the eutrophication level. In eutrophic estuaries such as the Warnow Estuary, the traditionally monitored parameters of total P (TP) and dissolved molybdate-reactive P (DRP) are not adequa...

The Saalian was one of the largest glaciations during the Quaternary with an ice sheet extending considerably wider into the Eurasian continent than during other glacials. Orbital variations caused the ice sheet to switch between growing and shrinking. The partial retreat of the ice sheet and meltwater discharge resulted in global sea-level rise an...

The Kimmeridge Clay Formation (KCF) is a laterally extensive, total-organic-carbon-rich succession deposited throughout northwest Europe during the Kimmeridgian–Tithonian (Late Jurassic). It has recently been postulated that an expanded Hadley cell, with an intensified but alternating hydrological cycle, heavily influenced sedimentation and total o...

Mn is one of the most abundant redox-sensitive metals on earth. Some microorganisms are known to use Mn(IV) oxide (MnO2) as electron acceptor for the oxidation of organic compounds or hydrogen (H2), but so far the use of sulfide (H2S) has been suggested but not proven. Here we report on a bacterial isolate which grows autotrophically and couples th...

Redox-sensitive trace metals are powerful tools for the reconstruction of modern and past redox conditions in aquatic ecosystems. The most prominent example is molybdenum (Mo), which behaves conservatively as soluble molybdate in the oxygenated ocean, but forms particle-reactive thiomolybdates at sufficiently high sulfide concentrations. Previous s...

The Kimmeridge Clay Formation (KCF) is a laterally extensive, total organic carbon-rich succession deposited throughout Northwest Europe during the Kimmeridgian–Tithonian (Late Jurassic). Here we present a petrographic and geochemical dataset for a 40 metre-thick section of a well-preserved drill core recovering thermally-immature deposits of the K...

The Black Sea is the world’s largest anoxic basin and a model system for studying processes across redox gradients. In between the oxic surface and the deeper sulfidic waters there is an unusually broad layer of 10–40 m, where neither oxygen nor sulfide are detectable. In this suboxic zone, dissolved phosphate profiles display a pronounced minimum...

The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenviro...

The deep basins of the Baltic Sea, including the Gotland and Landsort Deeps, are well-known for the exceptional occurrence of sedimentary Mn carbonate. Although the details of the mechanisms of Mn carbonate formation are still under debate, a close relationship with episodic major Baltic inflows (MBIs) is generally assumed, at least for the Gotland...

The reuse of effluent waters and sediments from African catfish (Clarias gariepinus) recirculation aquaculture systems requires a deeper understanding of the nutrient and energy flows and material pathways. Three semi-commercial systems, differing in stocking density, were sampled for nutritive and pollutant elements of the input- (tap water, feed)...

Sedimentary time markers based on the recent history of anthropogenic radionuclides or pollutants are extremely valuable in synchronizing and calibrating proxy-based records with instrumental data and observations. However, such time markers are rare for the early 20th century, and any additional time marker for this time period would be valuable f...

Salinity has a strong impact on bacterial community composition such that freshwater bacterial communities are very different from those in seawater. By contrast, little is known about the composition and diversity of the bacterial community in the sediments (bacteriobenthos) at the freshwater-seawater transition (mesohaline conditions). In this st...

The sediments of the Landsort Deep and Gotland Basin in the central Baltic Sea are strongly enriched in Mn carbonate. However, conceptual models attempting to explain the intense Mn carbonate precipitation in both basins are in part conflicting. In the Gotland Basin model, deposited Mn oxides are converted to Mn carbonate after the oxygenation of e...

Total particle flux, Barium and lithogenic trace element fluxes were measured at the mooring Kiel 276 (33°N, 22°W) in the deep-sea of the subtropical Northeast Atlantic. The particulate material was collected between 2002 and 2008 with a sediment trap in 2000m depth and analyzed with ICP-OES/-MS to determine its geochemical composition. The particl...

A METals In Situ analyzer (METIS) has been used to determine dissolved manganese (II) concentrations in the subhalocline waters of the Gotland Deep (central Baltic Sea). High-resolution in situ measurements of total dissolved Mn were obtained in near real-time by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). PAN is a complexing agent o...

The Littorina Sea stage (past c. 7000 years) development of the northern, and its interactions with the central Baltic Sea have been influenced by spatially different but in the north very strong glacio-isostatic uplift. Here we investigate the impact of the isostatic readjustment on the northern Baltic Sea environment and on the water exchange wit...

To gain insight into the bacterial communities involved in iron (Fe) cycling under marine conditions we analysed sediments with Fe-contents (0.5-1.5 wt %) from the suboxic zone at a marine site in the Skagerrak (SK) and a brackish site in the Bothnian Bay (BB) using 16S rRNA gene pyrosequencing. Several bacterial families, including Desulfobulbacea...

The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature varia...

There is ample evidence that tube-dwelling invertebrates such as chironomids significantly alter multiple important ecosystem functions, particularly in shallow lakes. Chironomids pump large water volumes, and associated suspended and dissolved substances, through the sediment and thereby compete with pelagic filter feeders for particulate organic...

The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature varia...

The redox-sensitive trace metal manganese (Mn) is an important electron donor and acceptor in aquatic environments. In stratified basins, the transformation between dissolved Mn2 +, 3 + and particulate Mn(III/IV) oxides constitutes the “manganese pump” at the redoxcline, which separates the oxic surface from anoxic bottom waters. In addition to flu...

The discharge of groundwater into the sea affects surrounding environments by changing the salinity, temperature and nutrient regimes. This work reports the spatial effects of a submarine groundwater discharge (SGD) on the abundance and structure of the meiofaunal community in the shallow area of Puck Bay (Baltic Sea). Several field expeditions in...

The last glacial-interglacial transition or Termination I (T I) is well documented in the Black Sea, whereas little is known about climate and environmental dynamics during the penultimate Termination (T II). Here we present a multi-proxy study based on a sediment core from the SE Black Sea covering the penultimate glacial and almost the entire Eem...

Analyzing the Beibu Gulf's hydrography and sediment properties is crucial for the understanding of naturally and anthropogenically induced matter and energy fluxes in the South China Sea's north-western coastal regions. For this reason, the present study combines hydrographical (T, S, σt, chlorophyll, nutrients, suspended particulate matter) and se...

Marine ecosystems worldwide are threatened by aquatic pollution; however, there is a paucity in data from the Caribbean region. As such, five heavy metals (arsenic, cadmium, copper, zinc, mercury) were measured in tissues of the scleractinian corals Porites furcata and Agaricia tenuifolia and in adjacent sediments in the Bocas del Toro Archipelago,...

A combined study of lithological, geochemical and physical sediment properties is reported from a completely laminated S5 sapropel, recovered in three gravity cores (M40-4 SL67, M51-3 SL103, M51-3 SL104) from the Pliny Trench region of the eastern Mediterranean. The thickness of the studied sapropel S5 varies between 85 and 91 cm and tops most S5-s...

The dynamics of the redox-sensitive trace metal manganese (Mn) and its response to biological activity were investigated in the water column and shallow pore waters of the German Wadden Sea (southern North Sea) in 2008 and 2009. Two systems, one from the southern (backbarrier area of Spiekeroog Island) and one from the eastern part (Sylt-Rømø Wadde...

De-embankment in the salt marshes of the island of Langeoog was carried out in 2004, thereby inducing an artificial transgression within an area of 2.2km2. Material from three suspended matter traps (SMTs) located along a N–S transect was collected monthly between January 2006 and February 2007. Besides geochemical (major and trace elements) and gr...

The barrier islands of the southern North Sea were formed during the Holocene sea-level rise. These islands form part of a highly dynamic environment whose evolution continues today. Subjected to sea-level changes, tides and storm events, the sedimentary record reflects processes occurring under varying energy conditions. This article presents geoc...

Experiments with water samples from the redoxclines of the Black Sea and the Baltic Sea identified a fraction of dissolved Mn which is completely oxidised to solid MnOx within less than 48 h at laboratory conditions. Disproportionation of this dissolved reactive Mn (dMnreact) into Mn (II) and Mn (IV) did not occur. Our data suggest that bacteria us...

Dissolved reactive Mn (dMnreact) has been determined at the redoxclines of two anoxic deeps from the Baltic Sea (Landsort Deep and Gotland Basin) and two seasonally anoxic freshwater lakes (Lake Dagow and Fuchskuhle, Germany). This dMnreact fraction is rapidly oxidised under oxygen atmosphere and is assumed to consist predominantly of Mn(III). Ther...

Following a tentative evidence for the occurrence of low-temperature barium manganese(II) carbonates in brackish sediments of the Baltic Sea, a stoichiometric double carbonate, BaMn[CO3]2, was synthesized from aqueous solutions at ambient temperature for the first time. Here we report the results of a multi-method approach, including scanning elect...

A decade of studies of metal and nutrient inputs to the back-barrier area of Spiekeroog Island, NW German Wadden Sea, have concluded that pore water discharge provides a significant source of the enrichments of many components measured in the tidal channels during low tide. In this paper we add studies of radium isotopes to help quantify fluxes int...

Here we present stable isotope data for vertical profiles of dissolved molybdenum of the modern euxinic water columns of the Black Sea and two deeps of the Baltic Sea. Dissolved molybdenum in all water samples is depleted in salinity-normalized concentration and enriched in the heavy isotope (δ98Mo values up to +2.9‰) compared to previously publish...

Continuous flow analysis for soluble Fe(II) species in seawater was performed with a colorimetric method using ferene as a spectrophotometric reagent. The method is based on the measurement of absorbance of the [FeII(fer)3]4 --complex at 594 nm. No preconcentration-steps are required. Samples prepared in the laboratory in line with external calibra...

Pelagic redoxclines of anoxic basins and deeps form the suboxic transition between oxygenated surface and anoxic or even sulfidic bottom waters. Intense element cycling, favoured by elevated microbial activity, causes steep gradients of physico-chemical parameters, nutrients and redox-sensitive trace metals. This study presents a conceptual model f...

In the tidal inlet of the back barrier area of Spiekeroog Island (Southern North Sea), nutrient concentrations (silica, phosphate, ∑ nitrite + nitrate) were determined hourly by an autonomously analysing system on a permanently installed time-series station from April 2006 to December 2008. Based on the high frequency of analyses we studied nutrien...

Salt marshes form part of the widely distributed intertidal landscape. The salt marshes of the East Frisian barrier island Langeoog (NW Germany) belong to the barrier-connected salt marsh type and were protected by a summer dike that was removed in 2004. In this study, pore water and sediment data were combined to investigate the effects of the de-...

Tidal and seasonal behaviour of the redox-sensitive trace metals Mn, Fe, Mo, U, and V have been investigated in the open-water column and shallow pore waters of the backbarrier tidal flats of the island of Spiekeroog (Southern North Sea) in 2002 and 2007. The purpose was to study the response of trace metal cycles on algae blooms, which are assumed...

The spatial and temporal distributions of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) was studied in the East-Frisian Wadden Sea (Southern North Sea) during several cruises between 2002 and 2005. The spatial distribution of CDOM in the German Bight shows a strong gradient towards the coast. Tidal and seasonal var...

Back-barrier tidal flat systems are characterized by basins and inlets through which water is exchanged with the coastal sea by tidal water movements. The hydrographic and morphometric properties at the inlets and in the basins vary considerably, but there is little information available how biogeochemical properties in the water column at these di...

Measurements of methane (CH4) so far have always shown supersaturation in the entire North Sea relative to the atmospheric partial pressure and the distribution of surface CH4 reveals a distinct increase towards the shore. Since North Sea sediments presumably are an insignificant source for CH4 the coastal contribution via rivers and tidal flats ga...