Island Of Sifnos Research Articles

Peristeriones (Περιστεριώνες), the typical pigeon houses in Sifnos Island (Cyclades, Greece)

This work takes into consideration the characteristic dovecotes of the Cycladic island of Sifnos. Their great importance that they had in the past for the agriculture of the island and the current architectural feature are analyzed.

Checklist updating and analysis of the flora of Sifnos Island and Kitriani Islet (Kiklades, Greece) with new noteworthy floristic records

Checklist updating and analysis of the flora of Sifnos Island and Kitriani Islet (Kiklades, Greece) with new noteworthy floristic records

Checklist updating and analysis of the flora of Sifnos Island and Kitriani Islet (Kiklades, Greece) with new noteworthy floristic records. ESF1

Checklist updating and analysis of the flora of Sifnos Island and Kitriani Islet (Kiklades, Greece) with new noteworthy floristic records. ESF1

Management of Hybrid Wind and Photovoltaic System Electrolyzer for Green Hydrogen Production and Storage in the Presence of a Small Fleet of Hydrogen Vehicles—An Economic Assessment

Nowadays, with the need for clean and sustainable energy at its historical peak, new equipment, strategies, and methods have to be developed to reduce environmental pollution. Drastic steps and measures have already been taken on a global scale. Renewable energy sources (RESs) are being installed with a growing rhythm in the power grids. Such installations and operations in power systems must also be economically viable over time to attract more investors, thus creating a cycle where green energy, e.g., green hydrogen production will be both environmentally friendly and economically beneficial. This work presents a management method for assessing wind–solar–hydrogen (H2) energy systems. To optimize component sizing and calculate the cost of the produced H2, the basic procedure of the whole management method includes chronological simulations and economic calculations. The proposed system consists of a wind turbine (WT), a photovoltaic (PV) unit, an electrolyzer, a compressor, a storage tank, a fuel cell (FC), and various power converters. The paper presents a case study of green hydrogen production on Sifnos Island in Greece through RES, together with a scenario where hydrogen vehicle consumption and RES production are higher during the summer months. Hydrogen stations represent H2 demand. The proposed system is connected to the main power grid of the island to cover the load demand if the RES cannot do this. This study also includes a cost analysis due to the high investment costs. The levelized cost of energy (LCOE) and the cost of the produced H2 are calculated, and some future simulations correlated with the main costs of the components of the proposed system are pointed out. The MATLAB language is used for all simulations.

Mixing Renewable Energy with Pumped Hydropower Storage: Design Optimization under Uncertainty and Other Challenges

Hybrid renewable energy systems, complemented by pumped hydropower storage, have become increasingly popular amidst the increase in renewable energy penetration. Such configurations are even more prosperous in remote regions that are typically not connected to the mainland power grid, where the energy independence challenge intensifies. This research focuses on the design of such systems from the perspective of establishing an optimal mix of renewable sources that takes advantage of their complementarities and synergies, combined with the versatility of pumped hydropower storage. However, this design is subject to substantial complexities, due to the multiple objectives and constraints to fulfill, on the one hand, and the inherent uncertainties, on the other, which span over all the underlying processes, i.e., external and internal. In this vein, we utilize a proposed hybrid renewable energy system layout for the Aegean Island of Sifnos, Greece, to develop and evaluate a comprehensive simulation-optimization scheme in deterministic and, eventually, stochastic settings, revealing the design problem under the umbrella of uncertainty. In particular, we account for three major uncertain elements, namely, wind velocity (natural process), energy demand (anthropogenic process), and wind-to-power conversion (internal process, expressed in terms of a probabilistic power curve). Emphasis is also given to the decision-making procedure regarding the system’s key design parameters (reservoir size and solar power capacity), which is achieved by thoroughly interpreting the uncertainty-aware optimization outcomes. Finally, since the proposed pumped hydropower storage uses the sea as the lower reservoir, additional technical challenges are addressed.

Water resources management in the framework of the circular economy for touristic areas in the Mediterranean: case study of Sifnos Island in Greece

Water resources management in the framework of the circular economy for touristic areas in the Mediterranean: case study of Sifnos Island in Greece

Sediment transport patterns and beach morphodynamics in the semi-enclosed bay of Platis Gialos, Sifnos Island, Aegean Sea

Sediment transport patterns and beach morphodynamics in the semi-enclosed bay of Platis Gialos, Sifnos Island, Aegean Sea

Proposal, application and partial validation of a simplified expression evaluating the stability of sandy slopes under rainfall conditions

One of the major causes of landslide triggering of sandy slopes is heavy rainfall occurrences. The present study (a) clarifies the mechanism of rainfall-induced failures of sandy slopes and (b) based on this mechanism proposes a simplified expression predicting the instability. The proposed expression in some aspects has a form similar to others previously proposed, but the novelty of the present study is that, by analysis, it is specified (a) in which type of soil it can be applied exclusively, (b) which is the depth of the sliding surface and (c) which drainage condition corresponds to the strength parameter and how to measure this parameter. In order to achieve this, first a simplified expression is proposed assessing the stability, based on the assumptions that (i) the problem can be treated as one-dimensional under drained conditions and (ii) temporary water flow exists just above a relatively impermeable inclined layer. Furthermore, the paper gives typical values of model parameters and predictions of the proposed equation. Next, it discusses the drained assumption used to obtain the proposed equation and the manner in which to measure the soil friction angle, needed in the proposed equation. Partial validation of the proposed equations is also performed at six well-documented landslides at two sites: Jiuzhaigou Park, China and Sifnos island, Greece, where geotechnical investigations are performed in order to establish the soil properties. Finally, it proposes, based on the developed equation, (i) a methodology assessing the stability of sandy slopes under rainfall conditions and (ii) mitigation measures.

Fluid capture during exhumation of subducted lithologies: A fluid inclusion study from Sifnos, Greece

We present phase equilibria modeling, combined with fluid inclusion microthermometry and textural observations, to constrain the composition and relative timing of subduction zone fluid-rock interaction during exhumation of two garnet-bearing blueschists from the northern part of the island of Sifnos, Greece. Water (H2O) from seawater was incorporated into the mafic lithologies by low-temperature water-rock interaction to produce hydrous phases, and was subsequently released during the subduction and exhumation cycle. Coupled phase equilibria modeling and textural observations suggest that fluid release resulted from the breakdown of the hydrous phases epidote and glaucophane, and some of the fluid was trapped as fluid inclusions in quartz. Homogenization temperatures and isochores of fluid inclusions are consistent with petrographic observations that suggest fluid inclusions were trapped during exhumation. Constructed isochores cross the inferred P-T path for Sifnos exhumation at pressures of ~0.3–1.0 GPa (~10–30 km depth) and temperatures of ~440–540 °C, suggesting fluid entrapment during the late stages of exhumation and cooling from peak subduction depths of ~70 km. The fluid inclusions have salinities of ~30–35 wt% NaCl equivalent, likely resulting from a multi-stage process that involves an increase in salinity during formation of hydrous minerals during subduction, leaving high salinity fluids and/or halide salts sequestered in pores. This is followed by the partial release of H2O during subsequent breakdown of high-pressure metamorphic phases, with later incorporation of H2O into newly forming retrograde phases. Portions of this fluid that interacted with earlier-formed saline fluids are now preserved as inclusions trapped in quartz. This interpretation suggests that fluid-rock interaction in the northern part of Sifnos occurred in a closed system, with a low water to rock mass ratio (~0.03 to ~0.05) and little to no infiltration of externally-derived lower salinity fluids. The closed system behavior is consistent with the observation that the blueschist unit is bounded by impermeable marble layers that limited exchange with external fluids during burial and/or exhumation.

A hybrid power plant towards 100% energy autonomy for the island of Sifnos, Greece. Perspectives created from energy cooperatives

The article presents the technical - economic details of a hybrid power plant, towards 100% electricity production for the autonomous island of Sifnos, Greece, following the initiative of the Sifnos Island Cooperative (SIC) to claim the island's energy independence and a sustainable future for the local community.In the case of Sifnos, energy independency is achievable given the high wind potential and the availability of an appropriate site for the installation of a seawater Pumped Hydro Storage system. Despite the low power demand (annual peak demand 6.5 MW), pumped storage remains the optimum energy storage technology, with a set-up specific cost of 30 €/kWh of storage capacity. The project's economic feasibility is ensured with a selling electricity total price of 0.29 €/kWh, given the production specific cost (0.34 €/kWh) of the existing thermal power plant.The hybrid power plant anticipates to constitute the kernel of the SIC objectives for a general social and economic development for the local community. This can be approached with the re-investment of the project's profits for the development of essential technical infrastructure and the exploitation of the electricity production surplus, combined with energy saving or smart-grid techniques, to foster new professional activities.

Anatomy of the Cycladic Blueschist Unit on Sifnos Island (Cyclades, Greece)

Since 35 Ma, the kinematics of the Aegean domain has been mainly controlled by the southward retreat of the African slab, inducing back-arc extension. The main structures and associated kinematics are well constrained, but the kinematics of deformation before 35 Ma, coeval with the exhumation of blueschists and eclogites of the Cycladic Blueschist Unit, is still poorly understood. The earlier Eocene syn-orogenic evolution is strongly debated and very different geometrical interpretations and kinematic histories have been proposed in the literature. This study focuses on the high-pressure and low-temperature (HP-LT) parageneses spectacularly exposed and well preserved on Sifnos Island. The new field work provides new structural constraints on the tectonic history of HP-LT units generated in the subduction zone during the Eocene. It further shows how lithological heterogeneities localize strain within an accretionary wedge and how the localisation of strain evolves through time during exhumation. We show, through new geological and metamorphic maps, cross-sections and analyses of kinematic indicators, that Sifnos is characterized by shallow-dipping shear zones reactivating weak zones due to competence contrasts or earlier tectonic contacts. Structures and kinematics associated with these shear zones, show a top-to-the-N to −NE ductile deformation. The lower part of the tectonic pile shows a downward gradient of shearing deformation and is actually a thick top-to-the-NE shear zone, which we name the Apollonia Shear Zone. Through time shearing deformation tends to localize downward, leaving the upper part of the subduction complex preserved from late deformation. The present-day shape and topography of the island is largely controlled by late brittle faults reworking the earlier ductile shear zones. Comparing with the nearby island of Syros, we propose a new tectono-metamorphic evolution of the Cycladic Blueschist Unit, which partly explains the different degrees of retrogression observed on the Cycladic Islands.

Genome sequence of Bradyrhizobium sp. WSM1253; a microsymbiont of Ornithopus compressus from the Greek Island of Sifnos.

Bradyrhizobium sp. WSM1253 is a novel N2-fixing bacterium isolated from a root nodule of the herbaceous annual legume Ornithopus compressus that was growing on the Greek Island of Sifnos. WSM1253 emerged as a strain of interest in an Australian program that was selecting inoculant quality bradyrhizobial strains for inoculation of Mediterranean species of lupins (Lupinus angustifolius, L. princei, L. atlanticus, L. pilosus). In this report we describe, for the first time, the genome sequence information and annotation of this legume microsymbiont. The 8,719,808 bp genome has a G + C content of 63.09 % with 71 contigs arranged into two scaffolds. The assembled genome contains 8,432 protein-coding genes, 66 RNA genes and a single rRNA operon. This improved-high-quality draft rhizobial genome is one of 20 sequenced through a DOE Joint Genome Institute 2010 Community Sequencing Project.Electronic supplementary materialThe online version of this article (doi:10.1186/s40793-015-0115-9) contains supplementary material, which is available to authorized users.

Ductile nappe stacking and refolding in the Cycladic Blueschist Unit: insights from Sifnos Island (south Aegean Sea)

New geological and structural mapping combined with kinematic and amphibole chemistry analyses is used to investigate the deformation history of the Cycladic Blueschist Unit (CBU) on Sifnos Island (Cyclades, Aegean Sea). We concentrate on north Sifnos, an area characterized by exceptionally well-preserved eclogites and blueschists. Our data show that the early, main phase (D2) of ductile deformation in the CBU occurred synchronous with the transition from prograde to close-to-peak retrograde conditions. This deformation phase took place at middle Eocene and is related to ESE-directed thrusting that emplaced the metavolcano-sedimentary subunit over the Marble subunit. The subsequent exhumation-related (D3) deformation is characterized by gently NE-plunging folds and NE-directed contractional shear zones that formed parallel to the axial planes of folds. NE-directed shearing occurred under blueschist and transitional blueschist-/greenschist-facies conditions during late Eocene–Oligocene and caused the restacking of the early nappe pile. We suggest that a mechanism of ductile extrusion of the CBU in a tectonic setting of net compression could explain better the recorded exhumation-related deformation than a mechanism of syn- and post-orogenic extension. Our new kinematic results in combination with previous works in the Cyclades area reveal a regional scale change in tectonic transport direction from (W)NW–(E)SE at Late Cretaceous–middle Eocene to (E)NE–(W)SW at late Eocene–Oligocene times. The observed change in transport direction may be governed by the relative motion of Africa with respect to Europe during Alpine orogeny.

A new genus of the millipede tribe Brachyiulini (Diplopoda: Julida: Julidae) from the Aegean region

A new genus of the julid tribe Brachyiulini, Enghophyllum gen. nov., is described, comprising two species from Greece. The type-species, E. naxium (Verhoeff, 1901) comb. nov. (ex Megaphyllum Verhoeff, 1894), appears to be rather widespread in the Aegean: it is known from Antiparos Island and Naxos Island (the type locality), both in the Cyclades, as well as East Mavri Islet, Dodecanese Archipelago (new record). The vulva of E. naxium is described for the first time. In addition, E. sifnium gen. et sp. nov. is described based on a single adult male from Sifnos Island, Cyclades. The new genus is distinct from other genera of the Brachyiulini mainly by its peculiar gonopod structure, apparently disjunct and at least mostly apomorphous: (1) promeres broad, shield-like, in situ protruding mostly posteriad, completely covering the opisthomeres and gonopodal sinus; (2) transverse muscles and coxal apodemes of promere fully reduced; (3) opisthomere with three differentiated processes, i.e., lateral, basal posterior and apical posterior; (4) solenomere rather simple, tubular. The evolution and biogeography of the new genus are briefly discussed, both suggesting its profoundly long isolation in the Aegean region from the contribal genera in the adjacent Balkans and Anatolia.

Using garnet to constrain the duration and rate of water-releasing metamorphic reactions during subduction: An example from Sifnos, Greece

We present a method to reconstruct the dehydration flux associated with garnet-forming reactions during subduction. Garnet-bearing blueschists from the island of Sifnos, Greece, in the Attic–Cycladic Blueschist Belt are used as a test case to extract information on the timescales of dehydration during subduction. We use garnet growth as a proxy for the net dehydration reaction. Thermodynamic (pseudosection) analysis of a mafic blueschist in this unit (representative of an altered basalt protolith) indicates that garnet grew via net reaction(s) of the form chlorite+chloritoid+glaucophane+phengite=garnet+pyroxene+lawsonite+paragonite+quartz+H2O. Garnet core and rim chemistry indicates that growth began at 2.0GPa and 460°C and ended at 2.2GPa and 560°C. The stabilization of matrix lawsonite (promoted by the bulk chemical shift of the matrix due to fractionation of the garnet and its inclusions from the system) throughout garnet growth limits the amount of water liberated from the rock over this P–T span. The average stoichiometry of the garnet-forming reaction(s) indicates an average molar production ratio of garnet to water of ~1.0:0.7. Given the 11vol.% garnet observed in the rock, this analysis indicates a loss of 0.3 to 0.4wt.% H2O from the bulk rock during garnet growth. Zoned garnet geochronology from these rocks provides a constraint on the dehydration rate from this lithology during the time span of garnet growth. Two garnet grains, roughly 1.5cm each in diameter, were microdrilled based on major element zoning contours. Three concentric growth zones were extracted from each garnet for Sm–Nd geochronology. Very low Nd concentrations in acid-cleansed garnet (0.03 to 0.09ppm) yielded very small samples (~1ng Nd) that were analyzed with TIMS using a NdO+ with Ta2O5 activator method. Untreated “garnet” powders rich in mineral inclusions from each garnet zone were also analyzed. The powders fall off of the garnet-matrix isochron, likely indicating age inheritance in the inclusions. Combining acid-cleansed garnet data from each garnet, multi-point garnet-matrix isochron ages of 46.50±0.80Ma for the core, 46.49±0.53Ma for the intermediate zone, and 46.46±0.59Ma for the rim were determined, indicating a brief growth duration of 0.04Ma with an upper bound (2 SD) on growth duration of 1.0Myr. This equates to a release of 0.3–0.4wt.% of water due to this reaction in this lithology, and heating of 100°C, in less than 1.0Myr. The short time interval represents a focused, rapid pulse of dehydration and heating within the context of the overall subduction descent timescale of ~10–20Myr.

Processes and patterns of landscape change on a small Aegean island: The case of Sifnos, Greece

The Mediterranean island landscape is a mosaic of land-cover types that manifest the historical interaction between physical and anthropogenic processes that have affected significantly landscape composition and spatial configuration. The aim of this study is to investigate the processes and patterns of landscape changes in small Mediterranean islands as exemplified by the Aegean island of Sifnos, Greece. Satellite imagery was used to measure land-cover changes from 1987 to 1999. A suite of landscape metrics was employed to quantify changes in landscape structure. The results show that cropland suffered the highest area loss through conversions to semi-natural vegetation or settlements. The maquis vegetation of Juniperus phoenicea expanded over time with hotspots of expansion mainly located away from settlements. Overall, Sifnos’ landscape became less fragmented and more homogeneous. The main drivers of landscape change were agricultural decline and tourism. These processes have resulted in semi-natural vegetation expansion and landscape closure. Landscape polarization of land-use intensity has increased with anthropogenic processes operating only on certain locations close to settlements and large parts of the island loosing their productivist profile. However, tourism should not be considered as the primary cause of land-use polarization but rather as an aggravating factor; agriculture and tourism do not represent competing economic sectors and land-use polarization is mainly the outcome of spatially co-occurring rather than spatially competing processes. Aegean island landscapes’ management needs to be pragmatic and as such adaptable to future emerging priorities.

Glaucophane schists and associated rocks from Sifnos (Cyclades, Greece): New constraints on the P–T evolution from oxidized systems

The island of Sifnos (Cyclades, Greece) is famous for its spectacular blueschist-facies rocks and eclogites. Their very well preserved high-pressure assemblages are characterized by the occurrence of Fe + 3 -rich minerals such as aegirine-rich pyroxene, riebeckite-rich amphibole, magnetite and deerite. Therefore, the common model system NCFMASH (Na 2O–CaO–FeO–MgO–Al 2O 3–SiO 2–H 2O), in which all iron is assumed to be ferrous, is not sufficient to completely model these highly oxidized assemblages. We propose new constraints on the P–T evolution of the glaucophane schists and associated rocks from Vroulidia Bay (northern Sifnos) using P–T isochemical diagrams (pseudosections) modelled for the oxidized N(K)CFMASHO system [Na 2O–(K 2O)–CaO–FeO–Fe 2O 3–MgO–Al 2O 3–SiO 2–H 2O], and calculated using solid solution models involving Fe + 3 -end-members. The resulting P–T conditions could be fitted by a simple trajectory consisting of a smooth clockwise P–T loop, with two distinct high-pressure events at T = 450–500 °C, P > 2.0 GPa (assemblage A) and T = 525–565 °C, P > 2.1 GPa (assemblage B), respectively, followed by cooling and decompression. Geospeedometry based on 40Ar/ 39Ar data, however, allows constraint as to the duration of individual thermal excursions associated with these events. Should these limits be taken into account, the P–T envelope derived in this paper encompasses a more complex P–T history, with individual excursions that potentially involve relatively short periods of temperature increase ± pressure variation.

Vegetation dynamics in abandoned crop fields on a Mediterranean island: Development of succession model and estimation of disturbance thresholds

This case study on the Sifnos island, Greece, assesses the main factors controlling vegetation succession following crop abandonment and describes the vegetation dynamics of maquis and phrygana formations in relation to alternative theories of secondary succession. Field survey data were collected and analysed at community as well as species level. The results show that vegetation succession on abandoned crop fields is determined by the combined effects of grazing intensity, soil and geological characteristics and time. The analysis determines the quantitative grazing thresholds that modify the successional pathway. Light grazing leads to dominance by maquis vegetation while overgrazing leads to phryganic vegetation. The proposed model shows that vegetation succession following crop abandonment is a complex multi-factor process where the final or the stable stage of the process is not predefined but depends on the factors affecting succession. An example of the use of succession models and disturbance thresholds as a policy assessment tool is presented by evaluating the likely vegetation impacts of the recent reform of the Common Agricultural Policy on Sifnos island over a 20–30-year time horizon.

A new autumn-flowering species ofAllium (Liliaceae)from the island of Sifnos (Cyclades, Greece)

Abstract Biel, B., Tan, K. & Tzanoudakis, D.: A new autumn-flowering species of Allium (Liliaceae) from the island of Sifnos (Cyclades, Greece). — Willdenowia 36 (Special Issue): 367–372. — ISSN 0511-9618; © 2006 BGBM Berlin-Dahlem. doi:10.3372/wi.36.36132 (available via http://dx.doi.org/) Allium apolloniensis is described as a species new to science, illustrated and compared with related species of A. sect. Codonoprasum. It is apparently restricted to the Cyclades in the central Aegean and of particular interest for the phylogeny of the genus because it is tetraploid (2n = 4x = 32).

Modelling the effects of human activity on the vegetation of a northeast Mediterranean island

Abstract. Question: Which factors affect the spatial variation of maquis and phryganic vegetation and how can the role of human activities be estimated through degradation models.Location: Island of Sifnos, Cyclades, Greece.Methods: Data on woody vegetation, environmental conditions and intensity of human activity were collected by field survey. The vegetation data were analysed using TWINSPAN. Models based on the combination of Canonical Variate Analysis and logistic regressions were used in order to examine and describe the different pathways of maquis degradation.Results: The spatial variation of maquis and phryganic vegetation was related to both environmental and disturbance factors. The replacement of maquis by phryganic vegetation can follow two different pathways which reflect differences on the environmental conditions. However, the pathways themselves are determined by the combinations and levels of disturbance only.Conclusion: Degradation models can provide essential information on the effects of human activities on the vegetation. Maquis vegetation is relatively tolerant of disturbance, however, if disturbance exceeds certain critical thresholds, maquis is replaced by phryganic vegetation. The presence of phryganic vegetation is not always the result of maquis degradation.