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Korrosionsempfindliche Dosimetermaterialien zur Überwachung der Umweltbedingungen an Kulturgütern

Die einzelnen Belastungsfaktoren von Kulturgütern können durch apparativ aufwendige und kostenintensive Einzelmessungen mit Hilfe der modernen Analytik genau bestimmt werden. Mit den sogenannten Glassensoren wurde am Fraunhofer-Institut für Silicatforschung (ISC) eine elegante und zerstörungsfreie Methode entwickelt, die ohne aufwendige Messungen der einzelnen Parameter die auftretenden Gesamtbelastungen über einen längeren Zeitraum hinweg registrieren kann. Die Verwendung von sensibilisierten Glasflächen als Dosimetermaterial wurde für den bisherigen Anwendungsbereich ausgeschöpft. Ziel dieses Vorhabens ist es, neue korrosionsempfindliche Materialien und Komponenten herzustellen und für den prinzipiellen Einsatz zur Überwachung der Umweltbedingungen an Kulturgütern zu prüfen. Zum einen sollen Granulate der bisherigen Glasmaterialien mit unterschiedlicher Körnung in eine NIR-transparente Trägermatrix aus SiO2-Aerogel eingebracht werden. Zum anderen bietet sich die Modifizierung der inneren Oberfläche von SiO2-Aerogelen an, die dann selbst als detektionsaktive Medien fungieren können. Ein weiterer Syntheseweg soll so gewählt werden, dass Aerogel- oder Xerogelschichten ohne überkritische Trocknung auf Glas als Trägermaterial hergestellt werden. In jedem Fall muss der korrosive Einfluss bestimmter Umweltfaktoren (Feuchte, Temperatur, Schadgase) in einem Expositionsprogramm in Klimakammern, zunächst durch Variation einzelner Parameter und schließlich durch deren Kombination systematisch charakterisiert werden. Nach Abschluss dieser Labortestphase können - bei Projektende - Expositionsprogramme in Museen verwirklicht werden.

Pore-water pH, H2S, Cl-, SO42-, SiO2, NO2-, PO43-, NH4+, NO3-, major and trace element data from MUC cores taken during RV HEINCKE cruises HE575 and HE595 in the Helgoland Mud Area, German Bight

This dataset includes downcore measurements of pH values, H2S, Cl-, SO42-, SiO2, NO2-, PO43-, NH4+, NO3-, As, Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Mo, P, Si and Sr concentrations for sediment cores retrieved using multi-corer sampling during RV Heincke expeditions HE575 and HE595 in 2021 and 2022, respectively. The samples were collected in the framework of the Project APOC (Anthropogenic impacts on particulate organic carbon cycling in the North Sea). All measurements were performed in the laboratories of the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, except pH values, which were determined onboard the research vessel.

Seawater carbonate chemistry and mass fluxes and elemental composition of particulate export in KOSMOS mesocosm experiments (2010-2014)

Diatoms account for up to 40% of marine primary production and require silicic acid to grow and build their opal shell. On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification. Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under pCO2 conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.

KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: dissolved inorganic nutrients, chlorophyll a and suspended particulate organic matter

We conducted a mesocosm study to investigate ecosystem responses to ocean alkalinity enhancement (OAE) in the temperate waters of the German North Sea on Helgoland in spring 2023. We simulated non-CO2-equilibrated OAE via calcium hydroxide through the addition of calcium chloride and sodium hydroxide. Twelve 6 m³ mesocosms were used to simulate two scenarios: in six mesocosms we established a gradient of added alkalinity from 0 to 1250 µmol/kg in increments of 250 µmol/kg, simulating immediate (imm) dilution of alkalised waters. For the second set of six mesocosms, alkalinity was added only to the top 1 m of each mesocosm, doubling the target added alkalinity. The top layer was mixed with the untreated bottom layer after 48 hours, simulating delayed dilution of alkalised waters (del) and ultimately leading to the same alkalinity gradient as the immediate dilution treatment. This data contains water column biogeochemical variables, including dissolved inorganic nutrient concentrations (µmol/L), chlorophyll a concentrations (µg/L) and suspended particulate matter (biogenic silica, particulate organic carbon, nitrogen and phosphate; µmol/L). Nutrients, particulate organic phosphate and biogenic silica were measured spectrophotometrically (Unicam UV 300, Thermo Spectronic, USA). High-performance liquid chromatography (Thermo Scientific HPLC Ultimate 3000) was performed for chlorophyll a determination and particulate organic carbon and nitrogen were measured using an elemental analyser (Flash EA, Thermo Fisher).

Elementkarte der Digitalen Lithogeochemischen Karte von Bayern 1:25.000 (dLGK25) - Siliziumdioxid (P90)

Die Elementkarte stellt die räumliche Verteilung der klassifizierten Gehalte des 90. Perzentils von Siliziumdioxid (in Gew.-%) innerhalb der 184 geochemischen Gesteinseinheiten in Bayern dar. In die Auswertung gehen dabei nur die Daten der ersten (von maximal drei) Lithologien einer geochemischen Gesteinseinheit ein. Für Informationen im Hinblick auf die Auswertung der Daten sowie auf die kartenmäßige Darstellung wird auf die Metadaten der digitalen Lithogeochemischen Karte 1:25 000 von Bayern (dLGK25) verwiesen.

Elementkarte der Digitalen Lithogeochemischen Karte von Bayern 1:25.000 (dLGK25) - Siliziumdioxid (P50)

Die Elementkarte stellt die räumliche Verteilung der klassifizierten Gehalte des 50. Perzentils von Siliziumdioxid (in Gew.-%) innerhalb der 184 geochemischen Gesteinseinheiten in Bayern dar. In die Auswertung gehen dabei nur die Daten der ersten (von maximal drei) Lithologien einer geochemischen Gesteinseinheit ein. Für Informationen im Hinblick auf die Auswertung der Daten sowie auf die kartenmäßige Darstellung wird auf die Metadaten der digitalen Lithogeochemischen Karte 1:25 000 von Bayern (dLGK25) verwiesen.

KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: sediment trap particle flux data and water column biogeochemistry

The data presented herein originates from a mesocosm study conducted as part of the BMBF CDRmare, Retake project (grant agreement no. 03F0895A), aimed at investigating the ecological ramifications of ocean alkalinity enhancement (OAE). Twelve mesocosms were deployed in Helgoland South Harbor, Germany, and systematically sampled using integrated water samplers over the period spanning from March 12th to April 20th, 2023. Six alkalinity levels under two dilution scenarios were established to differentiate between localized and uniform OAE additions. Alkalinity was increased stepwise to ΔTAmax = 1250 μmol kg-1 (250 μmol TA kg-1 increments) using sodium hydroxide (NaOH) with calcium chloride (CaCl2) to simulate cation release during calcium-based mineral dissolution, causing strong carbonate chemistry perturbations (e.g., pHT > 9.25). The dataset encompasses a spectrum of sediment trap particle flux data, water column biogeochemistry including pigment variables, inorganic nutrients, carbonate chemistry parameters. The study and data set offer insights into impacts of alkalinity enhancement on marine ecosystems and their associated biogeochemistry.

LGRB-BW HW_HYD: Siliziumdioxid

Die vorliegende Auswertung zeigt für Baden-Württemberg die geogenen Hintergrundkonzentrationen einer Vielzahl von Grundwasserinhaltsstoffen in Abhängigkeit von den durchflossenen Gesteinen. Sie liefert damit die Grundlage für die Definition von Warnwerten, Grenzwerten und Sanierungszielen in Regelwerken, in der Gesetzgebung und für die Praxis. Die Auswertung basiert auf Proben von oberflächennahen Grundwasseraufschlüssen mit extensiv genutzten, überwiegend bewaldeten oder als Weideland bewirtschafteten Einzugsgebieten. Die Methodik sowie die Ergebnisse der Auswertung sind in den LGRB-Informationen 23 (https://produkte.lgrb-bw.de/docPool/c621_data.pdf) ausführlich beschrieben.

Mesocosm experiment on the influence of heatwave on plankton

In the context of global change, marine organisms are subjected not only to gradual changes in abiotic parameters, but also to an increasing number of extreme events, such as heatwaves. However, we still know little about the influence of heatwaves on the structure of marine communities, and experimental studies are needed to test the impact of heatwaves alone, and in combination with other environmental drivers. Here, we conducted a mesocosm experiment and applied an integrated multiple driver design to assess the potential impact of heatwaves under ambient and future environmental conditions on natural coastal plankton communities. To represent future environmental conditions, temperature and pH were manipulated based on the Representative Concentration Pathway 8.5 proposed by the IPCC for 2100, and dissolved N:P ratios were increased to simulate the conditions expected in European coastal zones. Throughout the experiment, we measured abiotic conditions as well as the abundance of bacterioplankton, phytoplankton, and microzooplankton.

Physical and chemical parameters of sediment core SAC05 from Sacrower See (NE Germany) provide a robust reconstruction of climate change and human impact since 13,000 cal. BP

The 11.8 m-long composite sediment record from the hardwater lake of Sacrower See, located near the city of Potsdam (north-eastern Germany), has been characterised by a range of analytical techniques. These include magnetic susceptibility, chemical parameters (XRF core scanning, CNS analysis, biogenic silica) and stable isotopes (13C, 15N). The chronology covers the entire Holocene and the concluding Lateglacial (Alleröd, Younger Dryas) and is based on age-depth modelling using radiocarbon dates refined by the onset of the local varve chronology in 1870 CE (Lüder et al., 2006) and by the Laacher See Tephra, an isochrone dated to 13,000 cal. BP. It offers a detailed environmental reconstruction providing insights into depositional processes influenced by both natural climatic variations and human activities (Enters et al., 2009; Kirilova et al., 2009). The Lateglacial and Early Holocene are distinguished by the stabilisation of natural landscapes characterised by the presence of pine-birch (Alleröd) and mixed oak forests (Early Holocene). This development was interrupted by the climatic deterioration of the Younger Dryas, which resulted in a destabilisation of vegetation and increased natural soil erosion. It is evident that, for the first time around 5500 cal. BP, anthropogenic forest clearing became a factor, which subsequently led to increasing cultural soil erosion further accelerating during the Bronze Age (3600-3200 cal. BP), the Early Iron Age (2800-2600 cal. BP) and the Middle Ages (900-600 cal. BP). In the course of industrialisation since the 19th century, human impact underwent a transition from the destabilisation of soils to the phenomenon of eutrophication. This transition resulted in the occurrence of hypolimnetic anoxia, accompanied by the formation of carbonaceous varves.

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