Calcification-driven CO2emissions exceed blue Carbon sequestration in a carbonate seagrass meadow

Long-term Blue Carbon burial in seagrass meadows is complicated by other carbon and alkalinity exchanges that shape net carbon sequestration. We measured a suite of such processes, including denitrification, sulfur, and inorganic carbon cycling, and assessed their impact on air-water CO2 exchange in a typical seagrass meadow underlain by carbonate sediments. Eddy covariance measurements reveal a consistent source of CO2 to the atmosphere at an average rate of 610 ± 990 μmol m-2 hour-1 during our study and 700 ± 660 μmol m-2 hour-1 (6.1 mol m-2 year-1) over an annual cycle. Net alkalinity consumption by ecosystem calcification explains \u3e95% of the observed CO2 emissions, far exceeding organic carbon burial and anaerobic alkalinity generation. We argue that the net carbon sequestration potential of seagrass meadows may be overestimated if calcification-induced CO2 emissions are not accounted for, especially in regions where calcification rates exceed net primary production and burial

Postmortem Health and Pollution Investigations on Harbor Seals (Phoca vitulina) of the Islands Helgoland and Sylt

Helgoland and Sylt are important centers of tourism in the North Sea. Harbor and grey seals are one reason for the attraction of these islands. However, little is known about these local seal groups. The present postmortem health and pollution study describes a multiparameter investigation of five ill harbor seals which were shot for animal welfare reasons. Firstly, results of pathology and blood investigations support the bad prognosis of survival made in the field. Signs of inflammation in organs, malnutrition, a high-stress level, and reduced thyroid activity were found. Secondly, metal and organic contaminants were investigated. Metal pollutants in blood, liver, muscle, and kidney tissue were not elevated. Lead and mercury concentrations showed a decreased level compared to former studies. Additionally, interesting insights were found for several organic contaminants in comparison with other studies. The Helgoland seals may be influenced by the contaminants of the Elbe plume

The Coastal Observing System for Northern and Arctic Seas (COSYNA)

The Coastal Observing System for Northern and Arctic Seas (COSYNA) was established in order to better understand the complex interdisciplinary processes of northern seas and the Arctic coasts in a changing environment. Particular focus is given to the German Bight in the North Sea as a prime example of a heavily used coastal area, and Svalbard as an example of an Arctic coast that is under strong pressure due to global change. The COSYNA automated observing and modelling system is designed to monitor real-time conditions and provide short-term forecasts, data, and data products to help assess the impact of anthropogenically induced change. Observations are carried out by combining satellite and radar remote sensing with various in situ platforms. Novel sensors, instruments, and algorithms are developed to further improve the understanding of the interdisciplinary interactions between physics, biogeochemistry, and the ecology of coastal seas. New modelling and data assimilation techniques are used to integrate observations and models in a quasi-operational system providing descriptions and forecasts of key hydrographic variables. Data and data products are publicly available free of charge and in real time. They are used by multiple interest groups in science, agencies, politics, industry, and the public

The submarine Congo Canyon as a conduit for microplastics to the deep sea

The increasing plastic pollution of the world’s oceans represents a serious threat to marine ecosystems and has become a well-known topic garnering growing public attention. The global input of plastic waste into the oceans is estimated to be approximately 10 million tons per year and predicted to rise by one order of magnitude by 2025. More than 90% of the plastic that enters the oceans is thought to end up on the seafloor, and seafloor sediment samples show that plastics are concentrated in confined morphologies and sedimentary environments such as submarine canyons. These canyons are occasionally flushed by powerful gravity-driven sediment flows called turbidity currents, which transport vast volumes of sediment to the deep sea and deposit sediment in deep-sea fans. As such, turbidity currents may also transport plastics present in the canyon and bury plastics in deep-sea fans. These fans may therefore act as sinks for seafloor plastics. Here we present a comprehensive dataset showing the spatial distribution of microplastics in seafloor sediments from the Congo Canyon, offshore West Africa. Multicores taken from 16 locations along the canyon, sampled different sedimentary sub-environments including the canyon thalweg, canyon terraces, and distal lobe. Microplastics were extracted from the sediments by density separation and the polymer type, size, and shape of all individual microplastic particles were analysed using laser-direct infrared-spectroscopy (LDIR). Microplastic number concentrations in the sediments of the distal lobe are significantly higher than in the canyon, indicating that the Congo Canyon system is a highly efficient conduit for microplastic transport to the deep sea. Moreover, microplastic concentrations of >20,000 particles per kg of dry sediment were recorded in the lobe, which represent some of the highest ever recorded microplastic number concentrations in seafloor sediments. This shows that deep-sea fans can serve as hotspots and potential terminal sinks for seafloor microplastics

Seawater and sediment data from NOAH regions in the German Bight collected during the cruise HE395

NOAH aims to establish a comprehensive (geo-referenced) inventory of seabed properties in the German Bight by studying temporal and spatial variability in physical, sedimentological, chemical and biological influence on seabed properties using high-resolution model results and targeted surveys of new data in representative sediment provinces. In order to assess sedimentological, biochemical as well as anthropogenic pressures water and sediment samples were taken between at different NOAH regions in the German Bight between 05.03.2013 and 14.03.2013

Grain size distribution for sediment samples of the campaign Watt2014

The German Wadden Sea represents a central sink for the accumulation and further distribution of sediments and SPM originating from the big river systems Elbe, Weser, Ems and Rhine, the German bight as well as from the Wadden Sea area itself. Knowledge about the origin, transport and accumulation of these materials are in particular of importance for coastal protection or the quality status of the German coastal areas in terms of its pollution status. In order to assess the anthropogenic fingerprint of this region also in comparison to previous analysis water and sediment samples were taken between 10.06.2014 and 20.06.2014 at different Wadden Sea areas along the German coast. The surface sediment samples were taken by a box grab or directly using small cores during low tide from the selected Wadden Sea areas representing different sediment properties and were analyzed for their grain size distribution by laser diffraction

Grain size distribution for sediment samples of HEINCKE cruise HE422

NOAH aims to establish a comprehensive (geo-referenced) inventory of seabed properties in the German Bight by Studying temporal and spatial variability in physical, sedimentological, chemical and biological influence on seabed properties using high-resolution model results and targeted surveys of new data in representative sediment provinces. In order to assess sedimentological, biochemical as well as anthropogenic pressures water and sediment samples were taken at different NOAH regions in the German Bight between 02.05.2014 and 15.05.2014. The surface sediment samples were taken by a box grab and analyzed for their grain size distribution by laser diffraction