• European Marine Science
• Other research productsclose
• 2013-2022close
• European Commission close
• EU close
• GB close

Despite the current high level of safety and the efforts to make passenger ships resilient to most fire and flooding scenarios, there are still gaps and challenges in the marine emergency response and ship evacuation processes. Those challenges arise from the fact that both processes are complex, multi-variable problems that rely on parameters involving not only people and technology but also procedural and managerial issues. SafePASS Project, funded under EU’s Horizon 2020 Research and Innovation Programme, is set to radically redefine the evacuation processes by introducing new equipment, expanding the capabilities of legacy systems on-board, proposing new Life-Saving Appliances and ship layouts, and challenging the current international regulations, hence reducing the uncertainty, and increasing the efficiency in all the stages of ship evacuation and abandonment process.

We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40 % at 2000 m to ~80 % at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

Microplastics are substrates for microbial activity and can influence biomass production. This has potentially important implications at the sea-surface microlayer, the marine boundary layer that controls gas exchange with the atmosphere and where biologically produced organic compounds can accumulate. In the present study, we used large scale mesocosms (filled with 3 m3 of seawater) to simulate future ocean scenarios. We explored microbial organic matter dynamics in the sea-surface microlayer in the presence and absence of microplastic contamination of the underlying water. Our study shows that microplastics increased both biomass production and enrichment of particulate carbohydrates and proteins in the sea-surface microlayer. Importantly, this resulted in a 3% reduction in the concentration of dissolved CO2 in the underlying water. This reduction suggests direct and indirect impacts of microplastic pollution on the marine uptake of CO2, by modifying the biogenic composition of the sea’s boundary layer with the atmosphere.

Greenland ice cores provide information about past climate. Few impurity records covering the past 2 decades exist from Greenland. Here we present results from six firn cores obtained during a 426 km long northern Greenland traverse made in 2015 between the NEEM and the EGRIP deep-drilling stations situated on the western side and eastern side of the Greenland ice sheet, respectively. The cores (9 to 14 m long) are analyzed for chemical impurities and cover time spans of 18 to 53 years (±3 years) depending on local snow accumulation that decreases from west to east. The high temporal resolution allows for annual layers and seasons to be resolved. Insoluble dust, ammonium, and calcium concentrations in the six firn cores overlap, and the seasonal cycles are also similar in timing and magnitude across sites, while peroxide (H2O2) and conductivity both have spatial variations, H2O2 driven by the accumulation pattern, and conductivity likely influenced by sea salt. Overall, we determine a rather constant dust flux over the period, but in the data from recent years (1998–2015) we identify an increase in large dust particles that we ascribe to an activation of local Greenland sources. We observe an expected increase in acidity and conductivity in the mid-1970s as a result of anthropogenic emissions, followed by a decrease due to mitigation. Several volcanic horizons identified in the conductivity and acidity records can be associated with eruptions in Iceland and in the Barents Sea region. From a composite ammonium record we obtain a robust forest fire proxy associated primarily with Canadian forest fires (R=0.49).

Tides significantly affect polar coastlines by modulating ice shelf melt and modifying shelf water properties through transport and mixing. However, the effect of tides on the marine carbonate chemistry in such regions, especially around Antarctica, remains largely unexplored. We address this topic with two case studies in a coastal polynya in the south-eastern Weddell Sea, neighbouring the Ekström Ice Shelf. The case studies were conducted in January 2015 (PS89) and January 2019 (PS117), capturing semi-diurnal oscillations in the water column. These are pronounced in both physical and biogeochemical variables for PS89. During rising tide, advection of sea ice meltwater from the north-east created a fresher, warmer, and more deeply mixed water column with lower dissolved inorganic carbon (DIC) and total alkalinity (TA) content. During ebbing tide, water from underneath the ice shelf decreased the polynya's temperature, increased the DIC and TA content, and created a more stratified water column. The variability during the PS117 case study was much smaller, as it had less sea ice meltwater input during rising tide and was better mixed with sub-ice shelf water. The contrasts in the variability between the two case studies could be wind and sea ice driven, and they underline the complexity and highly dynamic nature of the system. The variability in the polynya induced by the tides results in an air–sea CO2 flux that can range between a strong sink (−24 mmol m−2 d−1) and a small source (3 mmol m−2 d−1) on a semi-diurnal timescale. If the variability induced by tides is not taken into account, there is a potential risk of overestimating the polynya's CO2 uptake by 67 % or underestimating it by 73 %, compared to the average flux determined over several days. Depending on the timing of limited sampling, the polynya may appear to be a source or a sink of CO2. Given the disproportionate influence of polynyas on heat and carbon exchange in polar oceans, we recommend future studies around the Antarctic and Arctic coastlines to consider the timing of tidal currents in their sampling strategies and analyses. This will help constrain variability in oceanographic measurements and avoid potential biases in our understanding of these highly complex systems.

The role of icebergs in narrow fjords hosting marine terminating glaciers in Greenland is poorly understood, even though icebergs provide a substantial freshwater flux that can exceed the subglacial discharge. Iceberg melt is distributed at depth, contributing to fjord stratification, thus impacting melt and dynamics of the glacier front. We model the high-silled Ilulissat Icefjord in Western Greenland with the MITgcm ocean model, using the IceBerg package to study the effect of icebergs on fjord properties, and compare our results with available observations from 2014. We find the subglacial discharge plume to be the primary driver of the seasonality of circulation, glacier melt and iceberg melt. Icebergs are necessary to include to correctly understand the properties of Ilulissat Icefjord, since they modify the fjord in three main ways: First, icebergs cool and freshen the water column within their vertical extent; Second, icebergs depress the neutral buoyancy depth of the plume and the outflow route of glacially modified water; Third, icebergs modify the deep basin, below their vertical extent, due to both increased entrainment of glacially modified water into the fjord, and iceberg modification of the incoming ambient water. Furthermore, the depressed neutral buoyancy depth of the plume limits melt to the deep section of the front of Sermeq Kujalleq (Jakobshavn Isbræ) even during peak summer, and thus promotes undercutting. We postulate that the impact of icebergs on the neutral buoyancy depth of the plume is a key mechanism connecting iceberg melange and glacier calving, independent of mechanical support.

Abstract P2.11 | 2nd ISMRM Iberian Chapter Annual Meeting | 27-28 June 2022, Lisbon, Portugal

Abstract P1.09 | 2nd ISMRM Iberian Chapter Annual Meeting | 27-28 June 2022, Lisbon, Portugal

Since 2000, and for the following 20 years, hydrological data of the Mediterranean Sea, with a particular focus on the western and central Mediterranean sub-basins, have been acquired to study the hydrodynamics at both coastal and open sea scales. In total, 1468 hydrological casts were realized in 29 oceanographic cruises planned due to scientific purposes linked with funding research projects but were also sometimes driven by sea conditions and type of vessel. After accurate quality assurance and control, following standard procedures, all hydrological data were included in four online public open-access repositories in SEANOE (SEA scieNtific Open data Edition), available from https://doi.org/10.17882/87567 (Ribotti et al., 2022). Hydrological and dissolved oxygen data are always present in all of the datasets, whereas pH, fluorescence, turbidity, and chromophoric dissolved organic matter (CDOM) are available just for some cruises. Samplings were carried out mainly along transects, with some repetition over the years. The results of two data analyses, i.e., staircase systems in the Tyrrhenian Sea and in the Algero-Provençal sub-basin and spreading of the Western Mediterranean Transient, are mentioned.

We present a record of melt events obtained from the East Greenland Ice Core Project (EastGRIP) ice core in central northeastern Greenland, covering the largest part of the Holocene. The data were acquired visually using an optical dark-field line scanner. We detect and describe melt layers and lenses, seen as bubble-free layers and lenses, throughout the ice above the bubble–clathrate transition. This transition is located at 1150 m depth in the EastGRIP ice core, corresponding to an age of 9720 years b2k. We define the brittle zone in the EastGRIP ice core as that from 650 to 950 m depth, where we count on average more than three core breaks per meter. We analyze melt layer thicknesses, correct for ice thinning, and account for missing layers due to core breaks. Our record of melt events shows a large, distinct peak around 1014 years b2k (986 CE) and a broad peak around 7000 years b2k, corresponding to the Holocene Climatic Optimum. In total, we can identify approximately 831 mm of melt (corrected for thinning) over the past 10 000 years. We find that the melt event from 986 CE is most likely a large rain event similar to that from 2012 CE, and that these two events are unprecedented throughout the Holocene. We also compare the most recent 2500 years to a tree ring composite and find an overlap between melt events and tree ring anomalies indicating warm summers. Considering the ice dynamics of the EastGRIP site resulting from the flow of the Northeast Greenland Ice Stream (NEGIS), we find that summer temperatures must have been at least 3 ± 0.6 ∘C warmer during the Early Holocene compared to today.