Mediterranean circulation perturbations over the last five centuries : relevance to past Eastern Mediterranean Transient-type events

Unidad de excelencia María de Maeztu MdM-2015-0552The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales

Physical forcing and physical/biochemical variability of the Mediterranean Sea: a review of unresolved issues and directions for future research

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries

Biogeochemical relationships between ultrafiltered dissolved organic matter and picoplankton activity in the Eastern Mediterranean Sea

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 57 (2010): 1460-1477, doi:10.1016/j.dsr2.2010.02.015.We targeted the warm, subsurface waters of the Eastern Mediterranean Sea (EMS) to investigate processes that are linked to the chemical composition and cycling of dissolved organic carbon (DOC) in seawater. The apparent respiration of semi-labile DOC accounted for 27 ± 18% of oxygen consumption in EMS mesopelagic and bathypelagic waters; this value is higher than that observed in the bathypelagic open ocean, so the chemical signals that accompany remineralization of DOC may thus be more pronounced in this region. Ultrafiltered dissolved organic matter (UDOM) collected from four deep basins at depths ranging from 2 to 4350 m exhibited bulk chemical (1H-NMR) and molecular level (amino acid and monosaccharide) abundances, composition, and spatial distribution that were similar to previous reports, except for a sample collected in the deep waters of the N. Aegean Sea that had been isolated for over a decade. The amino acid component of UDOM was tightly correlated with apparent oxygen utilization and prokaryotic activity, indicating its relationship with remineralization processes that occur over a large range of timescales. Principal component analyses of relative mole percentages of monomers revealed that oxygen consumption and prokaryotic activity were correlated with variability in amino acid distributions but not well correlated with monosaccharide distributions. Taken together, this study elucidates key relationships between the chemical composition of DOM and heterotrophic metabolism.TBM and AG acknowledge funding from the Hellenic GSRT/European Union (non-EU Grant No180) and SESAME Project (European Commission's Sixth Framework Program, EC Contract No GOCE-036949). TY was supported by the Japanese Society for the Promotion of Science (JSPS) Postdoctoral Fellowship for research abroad and DDC received a fellowship of the University of Groningen. Microbial laboratory work and molecular analyses were supported by a grant of the Earth and Life Science Division of the Dutch Science Foundation (ARCHIMEDES project, 835.20.023) to GJH. DJR and TBM were supported by grants from the Gordon and Betty Moore Foundation and from the C-MORE organization of NSF

Variability and Trends in Physical and Biogeochemical Parameters of the Mediterranean Sea during a Cruise with RV MARIA S. MERIAN in March 2018

The last few decades have seen dramatic changes in the hydrography and biogeochemistry of the Mediterranean Sea. The complex bathymetry and highly variable spatial and temporal scales of atmospheric forcing, convective and ventilation processes contribute to generate complex and unsteady circulation patterns and significant variability in biogeochemical systems. Part of the variability of this system can be influenced by anthropogenic contributions. Consequently, it is necessary to document details and to understand trends in place to better relate the observed processes and to possibly predict the consequences of these changes. In this context we report data from an oceanographic cruise in the Mediterranean Sea on the German research vessel Maria S. Merian (MSM72) in March 2018. The main objective of the cruise was to contribute to the understanding of long-term changes and trends in physical and biogeochemical parameters, such as the anthropogenic carbon uptake and to further assess the hydrographical situation after the major climatological shifts in the eastern and western part of the basin, known as the Eastern and Western Mediterranean Transients. During the cruise, multidisciplinary measurements were conducted on a predominantly zonal section throughout the Mediterranean Sea, contributing to the Med-SHIP and GO-SHIP long-term repeat cruise section that is conducted at regular intervals in the Mediterranean Sea to observe changes and impacts on physical and biogeochemical variables. The data can be accessed at https://doi.org/10.1594/PANGAEA.905902 (Hainbucher et al., 2019), https://doi.org/10.1594/PANGAEA.913512 (Hainbucher, 2020a) https://doi.org/10.1594/PANGAEA.913608, (Hainbucher, 2020b) https://doi.org/10.1594/PANGAEA.913505, (Hainbucher, 2020c) https://doi.org/10.1594/PANGAEA.905887 (Tanhua et al., 2019) and https://doi.org/10.25921/z7en-hn85 (Tanhua et al, 2020)

Realising consilience: How better communication between archaeologists, historians and natural scientists can transform the study of past climate change in the Mediterranean

This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past (“palaeoenvironmental sciences”), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia.This paper emerged as a result of a workshop at Costa Navarino and the Navarino Environmental Observatory (NEO), Greece in April 2014, which addressed Mediterranean Holocene climate and human societies. The workshop was co-sponsored by IGBP/PAGES, NEO, the MISTRALS/PaleoMex program, the Labex OT-Med, the Bolin Centre for Climate Research at Stockholm University, and the Institute of Oceanography at the Hellenic Centre for Marine Research. We also acknowledge funding from the National Science Centre, Poland, within the scheme of the Centre's postdoctoral fellowships (DEC-2012/04/S/HS3/00226 (A.I)); the Swedish Research Council (grant numbers 421-2014-1181 (E.W.) and 621-2012-4344 (K.H.)); CSIC-Ramón y Cajal post-doctoral program RYC-2013-14073 and Clare Hall College, Cambridge, Shackleton Fellowship (B.M.); the EU/FP7 Project ‘Sea for Society’ (Science and Society - 2011-1, 289066)

Μελέτη του βιογεωχημικού κύκλου βιογενών και ανθρωπογενών οργανικών ενώσεων στο θαλάσσιο περιβάλλον της βορειοανατολικής Μεσογείου

Ο κύκλος του οργανικού άνθρακα στο θαλάσσιο περιβάλλον της Βορειοανατολικής Μεσογείου διερευνήθηκε μέσω της χρήσης οργανικών μοριακών δεικτών (ΟΜΔ). Ειδικότερα, η μελέτη των αλειφατικών και πολυαρωματικών υδρογονανθράκων, των κ-αλκαναλών, των μέθυλο-κετονών και των κ-αλκανοϊκών οξέων σε συνδιασμό με την ανάλυση της αντίστροφης πορείας των αερίων μαζών, επέτρεψε την συσχέτιση των οργανικών αερολυμάτων που μεταφέρονται από τις περιοχές της ηπειρωτικής Ευρώπης και της βόρειας Αφρικής με τις χερσαίες και θαλάσσιες πηγές προέλευσης της οργανικής ύλης. Η παράλληλη μελέτη των ενώσεων χερσαίας βιογενούς και ανθρωπογενούς προέλευσης και των ΟΜΔ θαλάσσιας προέλευσης (στεροειδείς αλκοόλες, αλκενόνες, διόλες, κέτο-ολες και ισοπρενοειδείς ενώσεις) στο καθιζάνον σωματιδιακό υλικό της θαλάσσιας στήλης, συνέβαλλε σημαντικά στην κατανόηση του δυναμικού εισαγωγής του αλλόχθονου οργανικού υλικού στο θαλάσσιο περιβάλλον, και του ρόλου της αυτόχρθονου παραγωγικότητας για την κάθετη μεταφορά του οργανικού υλικού σε μεγαλύτερα βάθη. Τέλος, η μελάτη των προαναφερθέντων ΟΜΔ στα επιφανειακά ιζήματα, που αποτελούν τον τελικό αποδέκτη του οργανικού υλικού στο θαλάσσιο περιβάλλον, ευπέδειξε ότι σε ολιγοτροφικές περιοχές στο χερσαίο οργανικό υλικό συνεισφέρει σημαντικά στο ισοζύγιο του βιογεωχημικού κύκλου του οργανικού άνθρακα. Η σημαντική ποιοτική και ποσοτική συσχέτιση των ροών των ΟΜΔ στα αερολύματα, στο καθιζάνον σωματιδιακό υλικό στη στήλη του νερού και στο επιφανειακό θαλάσσιο ίζημα, υπέδειξε την ατμοσφαιρική εναπόθεση ως την κυριότερη οδό μεταφοράς του χερσαίου οργανικού υλικού στην ανοικτή θάλασσια περιοχή της Βορειοανατολικής Μεσογείου.The biogeochemical cycle of organic matter in the Northeastern Mediterranean Sea was studied by using the organic molecular marker (OMM) approach. Aliphatic and polyaromatic hydrocarbons, n-alkanals, n-alkan-2-ones, and aliphatic acids, and atmospheric backward trajectories have been conjointly used to reconcile organic aerosols transferred from continental Europe and North Africa with their emission sources. The study of the OMM, derived from terrestial higher plants and anthropogenic sources, in parallel with OMM of marine origin (steroidal alcohols, long-chain alkenones, diols, keto-ols and isoprenoids) in the sea-water sinking material, provided information concerning the impact of allochthonous organic matter inputs into the marine environment. The role of autochthonous productivity for the organic matter transport to higher water column depths was also highlighted. Finally, the study of OMM in the sea sediments, the ultimate sink in the marine environment, indicated that in oligotrophic marine seas, the contribution of terrestrial organic matter can contribute significantly to the mass balance of the organic carbon in its biogeochemical cycle. The significant qualitative and quantitative correlation of the atmospheric, sea-water sinking material and sediment accumulation fluxes, indicated that the atmospheric deposition is the main route for the transport of terrestrial organic matter in the open Northeastern Mediterranean Sea

Preparation and characterization of ZnO nanoparticles from different precursors and their photocatalytic activity on Rhodamine B

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Επιστήμη και Τεχνολογία Υλικών

Organic aerosols in Eastern Mediterranean: components source reconciliation by using molecular markers and atmospheric back trajectories

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Polycyclic aromatic hydrocarbons in surface sediments of the Aegean Sea (eastern Mediterranean Sea)

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