scholarly journals Marine Gas Hydrate Geohazard Assessment on the European Continental Margins. The Impact of Critical Knowledge Gaps

2021 ◽  
Vol 11 (6) ◽  
pp. 2865
Author(s):  
Ricardo León ◽  
Miguel Llorente ◽  
Carmen Julia Giménez-Moreno

This paper presents a geohazard assessment along the European continental margins and adjacent areas. This assessment is understood in the framework of the seafloor’s susceptibility to (i.e., likelihood of) being affected by the presence of hydrate deposits and the subsequent hazardous dissociation processes (liquefaction, explosion, collapse, crater-like depressions or submarine landslides). Geological and geophysical evidence and indicators of marine gas hydrates in the theoretical gas hydrate stability zone (GHSZ) were taken into account as the main factors controlling the susceptibility calculation. Svalbald, the Barents Sea, the mid-Norwegian margin-northwest British Islands, the Gulf of Cádiz, the eastern Mediterranean and the Black Sea have the highest susceptibility. Seafloor areas outside the theoretical GHSZ were excluded from this geohazard assessment. The uncertainty analysis of the susceptibility inference shows extensive seafloor areas with no data and a very low density of data that are defined as critical knowledge gaps.


2021 ◽  
Author(s):  
Ricardo León ◽  
Christopher Rochelle ◽  
André Burnol ◽  
Carmen Julia Giménez- Moreno ◽  
Tove Nielsen ◽  
...  

<p>The Pan-European gas-hydrate relate GIS database of GARAH project has allowed assessing the susceptibility of seafloor areas affected by hydrate dissociation. This study has been applied as a first step for the hydrate related risk assessment along the European continental margins. Several factors and variables have been taken into account. They have been defined by their relationship with the presence of hydrates below seafloor and weighted depending on the confidence of finding hydrates in this site. The maximum weight (or confidence) has been given to the recovered samples of gas hydrates or hydrate-dissociation evidences such as degassing or liquation structures observed in gravity cores. Seismic indicators of the presence of gas hydrate or hydrocarbon seabed fluid flow such as BSR, blanking acoustic, amplitude anomalies or the presence of geological structures of seabed fluid flow in the neighbouring of the GHSZ have been weighted with a lower value. The theoretical gas hydrate stability zone (GHSZ) for a standard composition for biogenic gas has been taken into account as another control factor and constrain feature. Seafloor areas out of the theoretical GSHZ have been excluded as potential likelihood to be affected by hydrate dissociation processes. The base of GHSZ has been classified as a critical area for these dissociation processes.</p><p>The proposed methodology analyses the geological hazard by means of the susceptibility assessment, defined by the likelihood of occurrence of hydrate dissociation, collapses, crater-like depressions or submarine landslides over seafloor. The baseline scenario is that gas hydrate occurrence is only possible in seafloor areas where pressure (bathymetry) and seafloor temperature conditions are inside the theoretical GHSZ. Inside GHSZ, the occurrence of gas hydrate is directly related to the presence of its evidences (direct samples of hydrates) or indicators (eg. pore water and velocity anomalies, BSR, gas chimneys, among others), as well as the occurrence of hydrocarbon fluid flow structures inside GHSZ. Finally, the likelihood of the seafloor to be affect gas hydrate dissociation processes will be major at the base of the GHSZ and in the neighbouring of the gas hydrate evidences and indicators. In order to proof this initial hypothesis, a susceptibility assessment has been carried out throughout map algebra in a GIS environment from a density map of evidences and indicators and the Pan-European map of the GHSZ over seafloor. Specifically, it has been conceived as a segmentation in three levels by quantiles resulting of the addition of the density map of evidences and indicators and the weighted map of the GHSZ over seafloor.</p><p> </p><p><strong>Acknowledgment</strong></p><p>GARAH project. GeoERA - GeoE.171.002</p>



2018 ◽  
Vol 19 (1) ◽  
pp. 79 ◽  
Author(s):  
ÇETIN KESKIN ◽  
DANIEL PAULY

  The mean trophic level, i.e., the Mean Trophic Index (MTI) and Mean Temperature of the Catch (MTC) were estimated for Turkish waters in the Eastern Mediterranean and the Black Sea based on the reconstructed marine fisheries catches (consisting of N = 88 species and/or higher taxa) of in Turkish waters for the year 1950 to 2010. The MTI decreased in both regions of Turkey, following expectations, but the MTC showed different trends in these two regions. It increased (by 0.48 °C·decade-1), along with the SST in the Eastern Mediterranean, while it fluctuated in the Black Sea. This fluctuating behaviour, however, was similar to the fluctuating tendency of SST in the Black Sea. This suggests that the MTI and MTC can be relied upon as indicators of fisheries impacts on ecosystems, and of the impact of changing temperatures on fisheries, respectively. 



2018 ◽  
Vol 477 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Oded Katz ◽  
Yariv Hamiel

AbstractWe analysed here, for the first time, 278 small to medium earthquakes that have occurred since 1985 along a 200 km section of the Levant passive continental margins, offshore Israel. The earthquakes are spatially overlapping with numerous submarine landslides and thin-skinned salt-tectonic-related faults scarps, bisecting the continental slope. Thus, we focus on the genetic relationship between the earthquakes, the faults and the landslides.We found that a subgroup of 55 earthquakes is spatially overlapping with the marine extension of the Carmel Fault and thus might be of tectonic origin. A second subgroup, hosting approximately 130 earthquakes, is spatially overlapping with the longshore salt-tectonic-related submarine faults. However, due to the non-shallow focal depth of most of these earthquakes, salt tectonics was ruled out as their possible seismic origin. Thus, the seismic source for theanalysed earthquakes is yet to be revealed.We further found that the observed medium earthquakes (M > 4) have a calculated reoccurrence time of more than 10 years and they are capable of inducing submarine slope failure within the studied area. Hence, they might play a role in submarine mass-wasting processes along the studied continental slope, and must now be considered in future hazard analysis.



2020 ◽  
Author(s):  
Ángela María Gómez-García ◽  
Álvaro González ◽  
Magdalena Scheck-Wenderoth ◽  
Denis Anikiev ◽  
Gaspar Monsalve ◽  
...  

<p>Active continental margins are potentially exposed to geohazards of different nature, including earthquakes and gas hydrate destabilisation, which may result in submarine landslides and devastating tsunamis. The northern margin of the South American plate is characterised by two flat-slab subductions: the Nazca plate from the west, and the Caribbean plate from the north. This defines a complex and poorly understood tectonic setting which poses a risk for the inhabitants of the region.</p><p>Gaining insight into the physical conditions (such as rock strength and temperature) at which earthquakes nucleate in this region requires building an improved lithospheric model, and determining the thermal and rheological states of the tectonic plates involved in this subduction system.</p><p>Combining 3D lithospheric-scale thermal and rheological modelling is a novel approach to establish the spatial variation of seismogenic zones, both at shallow and intermediate depths, thus providing crucial information about the range of conditions at which earthquakes may occur. This method is especially useful in regions like the South Caribbean where more classical approaches are limited because seismic records do not extend far back in time and the frequency of megathrust earthquakes is low.</p><p>Furthermore, in river-dominated continental margins, such as the South Caribbean, the destabilisation of gas hydrates deposits has been recently recognised as one of the most important triggering factors of submarine landslides. Gas hydrates are stable in low-temperature and high-pressure environments, normally found in marine sediments within continental slopes, with dominant temperatures ranging from 5°C to 10°C, at depths greater than 400 m. However, the gas hydrate stability zone is mainly controlled by the local geothermal gradient and the bottom water temperature, being both parameters influenced by the particular setting of each region.</p><p>Our research aims to evaluate the physical state of the seismogenic zones in the northern margin of the South American plate and Panama microplate, and to identify the locations of potential gas hydrates accumulation in the South Caribbean margin.</p><p>Here we present the complete workflow of this analysis, starting from the definition of an up-to-date 3D lithospheric-scale model which has been validated with the forward modelling of gravity anomalies. This model is the main input for calculating the 3D steady-state thermal field and the 3D pressure field, using the software LYNX. Based on our modelled results, we evaluate the rheological behaviour of the present-day lithospheric configuration, considering the locations of the earthquakes from the Bulletin of the International Seismological Centre. Finally, by modelling the temperature and pressure within the marine sediments, we constrain the spatial distribution of the potential gas hydrate stability zone.</p><p>With this work we exemplify how 3D lithospheric-scale thermal and rheological models may contribute to the assessment of geohazards in a region such as the Caribbean Sea, where hundreds of thousands of coastal inhabitants, tourists and infrastructures are potentially at risk.</p>



Author(s):  
Alba Rey-Iglesia ◽  
Philippe Gaubert ◽  
Gonçalo Espregueira Themudo ◽  
Rosa Pires ◽  
Constanza De La Fuente ◽  
...  

Abstract The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation. We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.



2021 ◽  
Vol 13 (4) ◽  
pp. 1798
Author(s):  
Patrik Rovný ◽  
Serhiy Moroz ◽  
Jozef Palkovič ◽  
Elena Horská

The main aim of our paper is to study peculiarities of two periods, i.e., the pre-conflict period (2004–2013) and conflict period (2014–2018), in the context of the impact of the demographic structure of the population on the economic growth and development of coastal regions of Ukraine. In the first step of the analysis, we investigate the relationship between the demographic shifts and selected economic indicators, using the Pearson’s correlation coefficient. In the next step of the analysis, we focus on the quantification of the impact of demographic indicators on the economic variables, based on the panel model with fixed effects. The received results confirm that the influence of the demographic stricture on the economic state of coastal regions changed significantly in the conflict period in comparison with the pre-conflict period, especially concerning income, unemployment, and the openness of the economy. Additionally, our findings show that while economic differences existed between the Azov Sea regions and the Black Sea regions in the pre-conflict period, they disappeared due to the economic deterioration of the Azov Sea regions during the conflict period. It is concluded that war affects adversely the population’s demographic structure, which inhibits the growth and economic development of Ukrainian coastal regions.



Author(s):  
Agata Di Noi ◽  
Silvia Casini ◽  
Tommaso Campani ◽  
Giampiero Cai ◽  
Ilaria Caliani

Honey bees and the pollination services they provide are fundamental for agriculture and biodiversity. Agrochemical products and other classes of contaminants, such as trace elements and polycyclic aromatic hydrocarbons, contribute to the general decline of bees’ populations. For this reason, effects, and particularly sublethal effects of contaminants need to be investigated. We conducted a review of the existing literature regarding the type of effects evaluated in Apis mellifera, collecting information about regions, methodological approaches, the type of contaminants, and honey bees’ life stages. Europe and North America are the regions in which A. mellifera biological responses were mostly studied and the most investigated compounds are insecticides. A. mellifera was studied more in the laboratory than in field conditions. Through the observation of the different responses examined, we found that there were several knowledge gaps that should be addressed, particularly within enzymatic and molecular responses, such as those regarding the immune system and genotoxicity. The importance of developing an integrated approach that combines responses at different levels, from molecular to organism and population, needs to be highlighted in order to evaluate the impact of anthropogenic contamination on this pollinator species.



2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1098.2-1099
Author(s):  
O. Russell ◽  
S. Lester ◽  
R. Black ◽  
C. Hill

Background:Socioeconomic status (SES) influences disease outcomes in rheumatoid arthritis (RA) patients. (1, 2) Differences in medication use could partly explain this association. (3) A scoping review was used to identify research conducted on this topic and determine what knowledge gaps remain.Objectives:To determine what research has been conducted on this topic, how this research has defined SES and medication use, and establish what knowledge gaps remain.Methods:MEDLINE, EMBASE and PsychInfo were searched from their inception until May 2019 for studies which assessed SES and medication use as outcome variables. Studies were included if they measured medication use and incorporated an SES measure as a comparator variable.SES was defined using any of the “PROGRESS” framework variables (4) including patients’ stated gender, age, educational attainment, employment, occupational class, personal income, marital status, health insurance coverage, area- (neighbourhood) level SES, or patients’ stated race and/or ethnicity. Medication use was broadly defined as either prescription or dispensation of a medicine, medication adherence, or delays in treatment. Data was extracted on studies’ primary objectives, measurement of specific SES measures, patients’ medication use, and whether studies assessed for differences in patients’ medication use according to SES variables.Results:1464 studies were identified by this search from which 74 studies were selected for inclusion, including 52 published articles. Studies’ publication year ranged from 1994-2019, and originated from 20 countries; most commonly from the USA.Studies measured a median of 4 SES variables (IQR 3-6), with educational achievement, area level SES and race/ethnicity the most frequently recorded.Likelihood of disease modifying antirheumatic drug (DMARD) prescription was the most frequent primary objective recorded.96% of studies reported on patients’ use of DMARDs, with glucocorticoids and analgesics being reported in fewer studies (51% and 23% respectively.)Most included studies found at least one SES measure to be significantly associated with differences in patients’ medication use. In some studies, however, this result was not necessarily drawn from the primary outcome and therefore may not have been adjusted for covariates.70% of published studies measuring patients’ income (n=14 of 20) and 58% of those that measured race/ethnicity (n=14 of 24) documented significant differences in patients’ medication use according to these SES variables, although the direction of this effect – whether it led to ‘greater’ or ‘lesser’ medication use – varied between studies.Conclusion:Multiple definitions of SES are used in studies of medication use in RA patients. Despite this, most identified studies found evidence of a difference in medication use by patient groups that differed by an SES variable, although how medication use differed was found to vary between studies. This latter observation may relate to contextual factors pertaining to differences in countries’ healthcare systems. Further prospective studies with clearly defined SES and medication use measures may help confirm the apparent association between SES and differences in medication use.References:[1]Jacobi CE, Mol GD, Boshuizen HC, Rupp I, Dinant HJ, Van Den Bos GA. Impact of socioeconomic status on the course of rheumatoid arthritis and on related use of health care services. Arthritis Rheum. 2003;49(4):567-73.[2]ERAS Study Group. Socioeconomic deprivation and rheumatoid disease: what lessons for the health service? ERAS Study Group. Early Rheumatoid Arthritis Study. Annals of the rheumatic diseases. 2000;59(10):794-9.[3]Verstappen SMM. The impact of socio-economic status in rheumatoid arthritis. Rheumatology (Oxford). 2017;56(7):1051-2.[4]O’Neill J, Tabish H, Welch V, Petticrew M, Pottie K, Clarke M, et al. Applying an equity lens to interventions: using PROGRESS ensures consideration of socially stratifying factors to illuminate inequities in health. J Clin Epidemiol. 2014;67(1):56-64.Acknowledgements:This research was supported by an Australian Government Research Training Program Scholarship.Disclosure of Interests:None declared



Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1345
Author(s):  
Oleg Bazaluk ◽  
Kateryna Sai ◽  
Vasyl Lozynskyi ◽  
Mykhailo Petlovanyi ◽  
Pavlo Saik

Ukraine is an energy-dependent country, with less that 50% of its energy consumption fulfilled by its own resources. Natural gas is of paramount importance, especially for industry and society. Therefore, there is an urgent need to search for alternative and potential energy sources, such as gas hydrate deposits in the Black Sea, which can reduce the consumption of imported gas. It is necessary to refine the process parameters of the dissociation of gas hydrate deposits with a heterogeneous structure. The analyzed known geological–geophysical data devoted to the study of the offshore area and the seabed give grounds to assert the existence of a significant amount of hydrate deposits in the Black Sea. An integrated methodological approach is applied, which consists of the development of algorithms for analytical and laboratory studies of gas volumes obtained during the dissociation of deposits with a heterogeneous structure. These data are used for the computer modelling of the dissociation zone in the Surfer-8.0 software package based on the data interpolation method, which uses three methods for calculating the volumes of modelling bodies. A 3D grid-visualization of the studied part of the gas hydrate deposit has been developed. The dissociation zone parameters of gas hydrate deposits with different shares of rock intercalation, that is, the minimum and maximum diameters, have been determined, and the potentially recoverable gas volumes have been assessed. The effective time of the process of gas hydrate deposit dissociation has been substantiated. The obtained research results of the dissociation process of gas hydrate deposits can be used in the development of new technological schemes for gas recovery from the deep-water Black Sea area.



Sign in / Sign up

Export Citation Format

Share Document