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A study on the winter season from October to March in the northern Atlantic Ocean was done, as fCO2 was found to be decoupled from sea surface temperature (SST) during the rest of the year. The changes in the speed of wind and atmospheric fCO2 accounted for most of the interannual variations of the computed air-sea CO2 fluxes and a tendency for increasing CO2 flux into the ocean with increasing values of the NAO index was identified.

Monitoring the marine environment for leaks from geological storage projects is a challenge due to the variability of the environment and the extent of the area that migrating CO2 might seep through the seafloor. Due to the environmental risk associated leaks should not be allowed to continue undetected. There is also a cost issue since marine operations are expensive, so false alarms should be avoided. The main question is then: how large a deviation in the monitoring data should cause mobilization of confirmation and localization procedures? Here Baye's theorem and Bayesian decision theory is suggested as a tool for quantifying certainties and to implement costs for false positives (false alarms) and false negatives (undetected leaks) in the decision procedure. The procedure is exemplified using modeled natural CO2 content variability and the predicted CO2 signal from a simulated leak. [ABSTRACT FROM AUTHOR]

Annular pancreas is an uncommon congenital abnormality characterized by a ring of pancreatic tissue around the duodenum descending part. It is exceptionally rare in adults and is increasingly detected after the investigation of symptoms caused by its consequences, which include recurrent pancreatitis, duodenal stenosis at the site of the annulus, or duodenal or gastric ulcers. In this study, we present a case report of symptomatic annular pancreas in an adult patient. A 23-year-old woman hospitalized for epigastric pain and recurrent vomiting. Radiological examination was consistent with an annular pancreas. At operation, a partial obstruction of the second part of the duodenum was found, caused by an annular pancreas. No other congenital anomaly of the intra-abdominal organs was noted. A gastrojejunostomy was performed and she was discharged after 8 days with good recovery. Because annular pancreas in adults is a rare clinical scenario, it should be included in the differential diagnosis of adult patients with gastrointestinal obstructive symptoms for a prolonged period of time, given that surgical intervention has a reliable outcome. • Annular pancreas in adults is a rare condition. • Symptomatic patients will develop symptoms of proximal bowel obstruction. • A CT scan can confirm the diagnosis after a gastroduodenoscopy. • Symptomatic patients need to actively pursue surgical intervention. [ABSTRACT FROM AUTHOR]

Abstract: The seasonal and interannual variability of the air–sea CO2 flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO2 (fCO2 sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO2 sw from phosphate (PO4), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO4 collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO2 sw estimates were combined with data for the atmospheric mole fraction of CO2, sea level pressure, and wind speed to evaluate F. The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO2. The monthly mean uptake increases nearly monotonically from 0.101 mol C m−2 in midwinter to 0.656 mol C m−2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ±0.071 mol C m−2 month−1. The variability is controlled mainly through combined variation of fCO2 sw and wind speed. The annual mean uptake of atmospheric CO2 in the region was estimated to 4.27±0.68 mol C m−2. [Copyright &y& Elsevier]

• Approaches for CO 2 leakage detection, attribution and quantification monitoring exist. • Many approaches cover multiple monitoring tasks simultaneously. • Sonars and chemical sensors on ships or AUVs can cover large areas. • Newer, more specific technologies can detect, verify and quantify smaller, localised leaks. Environmental monitoring of offshore Carbon Capture and Storage (CCS) complexes requires robust methodologies and cost-effective tools to detect, attribute and quantify CO 2 leakage in the unlikely event it occurs from a sub-seafloor reservoir. Various approaches can be utilised for environmental CCS monitoring, but their capabilities are often undemonstrated and more detailed monitoring strategies need to be developed. We tested and compared different approaches in an offshore setting using a CO 2 release experiment conducted at 120 m water depth in the Central North Sea. Tests were carried out over a range of CO 2 injection rates (6 - 143 kg d−1) comparable to emission rates observed from abandoned wells. Here, we discuss the benefits and challenges of the tested approaches and compare their relative cost, temporal and spatial resolution, technology readiness level and sensitivity to leakage. The individual approaches demonstrate a high level of sensitivity and certainty and cover a wide range of operational requirements. Additionally, we refer to a set of generic requirements for site-specific baseline surveys that will aid in the interpretation of the results. Critically, we show that the capability of most techniques to detect and quantify leakage exceeds the currently existing legal requirements. [ABSTRACT FROM AUTHOR]

• A novel stoichiometric approach called the Cseep method was developed and used to. • Predict natural DIC variations around the Goldeneye site in the north-western North Sea. • Establish a process-based baseline DIC concentration (Cb) with minimal variability. • Determine CO2 seepage detection threshold (DT) to reliably differentiate subsea released−CO 2 signal from natural variability. • Quantify DIC concentration of subsea released−CO 2 dissolved in the sampled seawater. Carbon Capture and Storage (CCS) is a potential significant mitigation strategy to combat climate change and ocean acidification. The technology is well understood but its current implementation must be scaled up nearly by a hundredfold to become an effective tool that helps meet mitigation targets. Regulations require monitoring and verification at storage sites, and reliable monitoring strategies for detection and quantification of seepage of the stored carbon need to be developed. The C seep method was developed for reliable determination of CO 2 seepage signal in seawater by estimating and filtering out natural variations in dissolved inorganic carbon (C). In this work, we analysed data from the first-ever subsea CO 2 release experiment performed in the north-western North Sea by the EU STEMM−CCS project. We successfully demonstrated the ability of the C seep method to (i) predict natural C variations around the Goldeneye site over seasonal to interannual time scales; (ii) establish a process-based baseline C concentration with minimal variability; (iii) determine CO 2 seepage detection threshold (DT) to reliably differentiate released−CO 2 signal from natural variability and quantify released−CO 2 dissolved in the sampled seawater. DT values were around 20 % of the natural C variations indicating high sensitivity of the method. Moreover, with the availability of DT value, the identification of released−CO 2 required no pre-knowledge of seepage occurrence, but we used additional available information to assess the confidence of the results. Overall, the C seep method features high sensitivity, automation suitability, and represents a powerful future monitoring tool both for large and confined marine areas. [ABSTRACT FROM AUTHOR]

• The classical set cover problem was used to optimize chemical sensors layout on the seafloor. • Multiple leak scenarios were simulated using an advection–diffusion equation with the currents data obtained from GCM. • The anomaly threshold was calculated using the C-seep method. • Different costs were incorporated in the monitoring design and the results were compared. Assurance monitoring of the marine environment is a required and intrinsic part of CO 2 storage project. To reduce the costs related to the monitoring effort, the monitoring program must be designed with optimal use of instrumentation. Here we use solution of a classical set cover problem to design placement of an array of fixed chemical sensors with the purpose of detecting a seep of CO 2 through the seafloor from an unknown location. The solution of the problem is not unique and different aspects, such as cost or existing infrastructure, can be added to define an optimal solution. We formulate an optimization problem and propose a method to generate footprints of potential seeps using an advection–diffusion model and a stoichiometric method for detection of small seepage CO 2 signals. We provide some numerical experiments to illustrate the concepts. [ABSTRACT FROM AUTHOR]

• We show strong increasing trends in the seasonal surface water f CO 2 in the northern Barents Sea and Nansen Basin. • The strong trends are correlated to a sharp decline in sea ice concentration. • Increases in salinity, reflecting an Atlantification of the area, contribute to the strong trends in the surface water f CO 2. Maps of surface water fugacity of CO 2 (f CO 2) over eastern Fram Strait, south-western Nansen Basin, and the north-western Barents Sea (73–84°N, 5–46°E) from September 1997 to December 2020 were made and used to investigate seasonal and temporal trends. The mapping utilized a neural network technique, the self-organizing map (SOM), that was trained with different combinations of satellite/observational/model data of sea surface temperature (SST), sea surface salinity (SSS), mixed layer depth (MLD), chlorophyll a (Chl a), sea ice concentration, and atmospheric mole fraction of CO 2 (xCO 2). The trained SOM was labelled with available surface ocean f CO 2 data, and the labelled SOM was subsequently used to map the f CO 2. The produced maps reveal that f CO 2 in northern Barents Sea, at the border of the Nansen Basin, has increased significantly over the last decades by between 4.2 and 5.5 ± 0.6–1.1 µatm yr−1 over the winter to summer seasons. These rates are twice the rate of atmospheric CO 2 increase, which was about 2 µatm yr−1. The spatial pattern coincides with the strongest decreases in sea ice concentration as well as with a salinification of the surface water. The former allows for a prolongation of the air-sea CO 2 flux with resultant oceanic CO 2 uptake in previously ice-covered waters, and the latter is caused by a shift from Arctic Water dominance to more saline waters containing more dissolved inorganic carbon, most likely of Atlantic Water origin although brine-release influenced deep water may also contribute. [ABSTRACT FROM AUTHOR]

Gridded fields of sea surface temperature (SST), sea level pressure (SLP), and wind speed were used in combination with data for the atmospheric mole fraction of CO2 and an empirical relationship between measured values of the fugacity of carbon dioxide in surface water and SST, to calculate the air–sea CO2 flux in the northern North Atlantic. The flux was calculated for each of the months October–March, in the time period 1981 until 2001, allowing for an assessment of the interannual variations in the region. Locally and on a monthly time scale, the interannual variability of the flux could be as high as ±100% in regions seasonally covered by sea ice. However, in open-ocean areas the variability was normally between ±20% and ±40%. The interannual variability was found to be approximately halved when fluxes averaged over each winter season were compared. Summarised over the whole northern North Atlantic, the air to sea carbon flux over winter totalled 0.08 Gton, with an interannual variability of about ±7%. On a monthly basis the interannual variations were slightly higher, about ±8% to ±13%. Changes in wind speed and atmospheric fCO2 (the latter directly related to SLP variations) accounted for most of the interannual variations of the computed air–sea CO2 fluxes. A tendency for increasing CO2 flux into the ocean with increasing values of the NAO index was identified. [Copyright &y& Elsevier]