Assessment of the sensitivity of the southern coast of the Gulf of Corinth (Peloponnese, Greece) to sea-level rise

The eustatic sea-level rise due to global warming is predicted to reach approximately 18?C59 cm by the year 2100, which necessitates the identification and protection of sensitive sections of coastline. In this study, the classification of the southern coast of the Gulf of Corinth according to the sensitivity to the anticipated future sealevel rise is attempted by applying the Coastal Sensitivity Index (CSI), with variable ranges specifically modified for the coastal environment of Greece, utilizing GIS technology. The studied coastline has a length of 148 km and is oriented along the WNW-ESE direction. CSI calculation involves the relation of the following physical variables, associated with the sensitivity to long-term sea-level rise, in a quantifiable manner: geomorphology, coastal slope, relative sea-level rise rate, shoreline erosion or accretion rate, mean tidal range and mean wave height. For each variable, a relative risk value is assigned according to the potential magnitude of its contribution to physical changes on the coast as the sea-level rises. Every section of the coastline is assigned a risk ranking based on each variable, and the CSI is calculated as the square root of the product of the ranked variables divided by the total number of variables. Subsequently, a CSI map is produced for the studied coastline. This map showed that an extensive length of the coast (57.0 km, corresponding to 38.7% of the entire coastline) is characterized as highly and very highly sensitive primarily due to the low topography, the presence of erosionsusceptible geological formations and landforms and fast relative sea-level rise rates. Areas of high and very high CSI values host socio-economically important land uses and activities.     

Spectral characteristics of rocks: Effects of composition and texture and implications for the interpretation of planet surface compositions

In spectroscopic remote sensing for the exploration of the surface compositions of Earth and terrestrial planets, reflectance spectra with very low spectral contrast and even devoid of diagnostic absorption bands can be observed, which make the interpretation of the component minerals ambiguous. Using selected examples of terrestrial rock samples from intrusive and effusive geologic systems, we discuss compositional and textural properties related to these particular spectral shapes. We show that: (1) this spectral behaviour is common for coarse grains of multimineral rocks, where the optical coupling is expected to occur between welded mineral particles; (2) it is emphasised by the presence of opaque minerals with various compositions, such as ulvospinel, magnetite and chromite in effusive rock groundmass and in intrusive rocks; (3) it is controlled by the number of silicate phases within which the FeO is distributed, irrespective of the total iron content in the rock: a rock composition with a high number of iron-bearing minerals producing this kind of low contrast, almost featureless spectra is indicated here as “critical mode”; (4) it is also strongly intensified by aqueous alteration of silicates.These observations suggest unpredictable combinations of several different petrographic variables affecting the spectra of some compact rocks, and stimulate both targeted studies to quantitatively relate spectral and petrographic parameters, and the development of appropriate methods of spectral decomposition. Our ongoing work is at present focused on the spectroscopic effects of the FeO concentration in transparent neutral plagioclase, the different compositions of the opaque neutral minerals, and the iron bearing amorphous phases.We also discuss the analogy between the rocks used in the analysis reported here and the crustal rock compositions observed on Mars and inferred for Mercury as well as the compatibility of the factors responsible for the low spectral contrast of terrestrial rock samples with the factors expected for the two planets. We observe that a coarse-grained surface and a composition approaching a critical mode could explain the featureless Acidalia spectra on Mars, and suggest that the still open questions about Mercury’s surface regolith characteristics and composition do not exclude a priori the contribution of some of the factors examined in this paper to the peculiar surface properties of this planet.     

Mercury crater statistics from MESSENGER flybys: Implications for stratigraphy and resurfacing history

The primary crater population on Mercury has been modified by volcanism and secondary craters. Two phases of volcanism are recognized. One volcanic episode that produced widespread intercrater plains occurred during the period of the Late Heavy Bombardment and markedly altered the surface in many areas. The second episode is typified by the smooth plains interior and exterior to the Caloris basin, both of which have a different crater size-frequency distribution than the intercrater plains, consistent with a cratering record dominated by a younger population of impactors. These two phases may have overlapped as parts of a continuous period of volcanism during which the volcanic flux tended to decrease with time. The youngest age of smooth plains volcanism cannot yet be determined, but at least small expanses of plains are substantially younger than the plains associated with the Caloris basin. The spatial and temporal variations of volcanic resurfacing events can be used to reconstruct Mercury's geologic history from images and compositional and topographic data to be acquired during the orbital phase of the MESSENGER mission.     

Radius and limb topography of Mercury obtained from images acquired during the MESSENGER flybys

Analysis of images obtained by the MESSENGER spacecraft during its three flybys of Mercury yields a new estimate for the planet's mean radius of 2439.25±0.69 km, in agreement with results from Mariner 10 and Earth-based observations, as well as with MESSENGER altimeter and occultation data. The mean equatorial radius and polar radius are identical to within error, suggesting that rotational oblateness is negligible when compared with other sources of topography. This result is consistent with the small gravitational oblateness of the planet. Minor differences in radius obtained at different locations reflect regional variations in topography. Residual topography along three limb profiles has a dynamic range of 7.4 km and a root-mean-square roughness of 0.8 km over hemispherical scales. Following MESSENGER's entry into orbit about Mercury in March 2011, we expect considerable additional improvements to our knowledge of Mercury's size and shape.     

Seismic effects of the Caloris basin impact, Mercury

Striking geological features on Mercury's surface have been linked to tectonic disruption associated with the Caloris impact and have the potential to provide information on the interior structure of Mercury. The unusual disrupted terrain located directly at the antipode of the 1500-km-diameter Caloris basin could have plausibly formed as a consequence of focused seismic waves generated by the massive impact event. In this paper, we revisit the antipodal seismic focusing effects of the Caloris impact by developing physically consistent structure models for Mercury and parameterized seismic source models for the Caloris impact. If the focused seismic body waves caused the disrupted terrain, then the amplitudes of the waves and the areal extent of surface disruptions could be used for estimating the seismic energy imparted by the impact.In this study, we show that effects of direct body waves are small relative to those of focused guided waves. Two types of guided waves are produced by the Caloris impact. One is the conventional Rayleigh wave generated by the impact. The second is the mantle guided waves trapped between the core and the free surface. Mantle guided waves, not recognized in previous studies, may have played an important role in the creation of the disrupted terrain. We find that the early core state has only moderate effects on the antipodal response to the Caloris impact. The fact that the zone of predicted disruption for both fluid and solid core cases is smaller than the observed region of chaotic terrain suggests either that the antipodal response to the Caloris impact was modulated by the shallow structure of Mercury, or that the energy imparted by the impact was larger than those used in this study.     

On the central configurations of the planar 1 + 3 body problem

We consider the Newtonian four-body problem in the plane with a dominat mass M. We study the planar central configurations of this problem when the remaining masses are infinitesimal. We obtain two different classes of central configurations depending on the mutual distances between the infinitesimal masses. Both classes exhibit symmetric and non-symmetric configurations. And when two infinitesimal masses are equal, with the help of extended precision arithmetics, we provide evidence that the number of central configurations varies from five to seven.     

Structural investigations of the two polymorphs of synthetic Fe-cordierite and Raman spectroscopy of hexagonal Fe-cordierite

The crystal structures of synthetic hexagonal and orthorhombic Fe-cordierite polymorphs with the space groups P6/mcc and Cccm were refined from single-crystal X-ray diffraction data to R _{1, hex}?=?3.14 % and R _{1, ortho}?=?4.48 %. The substitution of the larger Fe²⁺ for Mg leads to multiple structural changes and an increase of the unit cell volumes, with a, c (hex)?=?9.8801(16) Å, 9.2852(5) Å and a, b, c (ortho)?=?17.2306(2) Å, 9.8239(1) Å, 9.2892(1) Å in the end-members. Furthermore Fe incorporation results in an increase of the volumes of the octahedra, although the diameters of the octahedra in direction of the c-axis decrease in both polymorphs. X-ray powder diffraction analysis indicates a high degree of Al/Si ordering in the orthorhombic polymorph, the Miyashiro distortion index is ~0.24. Estimations of site occupancies based on the determined tetrahedral volumes result in the following values for hexagonal Fe-cordierite: ~73 % Al for T₁ and ~28 % Al for T₂. For the first time Raman spectroscopy was performed on the hexagonal Fe-cordierite polymorph. In the hexagonal Fe-cordierite polymorph most Raman peaks are shifted towards lower wavenumbers when compared with the Mg-end-member.     

Relationship between hydrogeological parameters for data-scarce regions: the case of the Araripe sedimentary basin, Brazil

This paper applies and validates a method for generating spatially distributed hydraulic conductivity (k) based on the specific capacity (Q _s) for data-scarce regions. This method has been applied to the Araripe sedimentary basin, Brazil, and consists of four steps: (1) selection of (32) wells for which both k and Q _s data are available; (2) estimation of k as a function of Q _s for the (128) wells for which only specific capacity data are available; (3) spatial distribution of k using the kriging geostatistical tool; (4) validation of the method, using (17) representative wells with k measured data. The equation relating k and Q _s showed a statistically significant linear relationship (R = 0.93), from which a database has been generated using kriging with the spherical model. The results showed a calibration coefficient of Nash and Sutcliffe (NS) of 0.54 and moderate spatial dependence ratio of 69 %. The validation process provided only a moderate efficiency (NS = 0.22), possibly due to the geological complexity of the focus system. Despite its limitations, the method indicates the possibility of application of ordinary kriging to generate reliable data from auxiliary variables, especially for the water management of data-scarce areas.     

Treatment of an ECF bleaching effluent with white-rot fungi in an air-lift bioreactor

Pulp and paper mills utilise huge amount of natural resources, inorganic and organic materials along with large volume of water in different stages of paper manufacturing, resulting in a significant volume of effluents. The aim of this work was to investigate the treatment of a bleaching effluent [effluent chlorine free (ECF)] from the cellulose industry with white-rot fungi in an air-lift bioreactor. This effluent was submitted to the biological treatment with three white-rot fungi, and, every 24 h for 120 h, analytical tests were performed to analyse the quality parameters of treatment (COD, phenols, colour, pH). Before and after treatment, the effluent was analysed as its molecular mass distribution and absorptivity in the UV/VIS. Lentinus edodes, Trametes versicolor and Trametes villosa promoted similarly significant reductions in the following characteristics: (a) effluent colour (40–44 %), (b) total phenol (30–51 %) and (c) COD (37–43 %). The UV/visible spectrometry reading of the effluent after the fungi treatment showed a reduction in the absorbance of all wavelengths between 260 and 500 nm. The size exclusion HPLC profile of the effluent was modified, and the treatment promoted changes in the intensity of the peaks associated with compounds of high and low molecular weight. Phenoloxidases were produced during the treatment. T. versicolor produced the highest levels of laccase, and L. edodes was the only fungus that produced peroxidases.     

Seasonal and spatial variations of water quality,substrate and aquatic macrophytes based on side scan sonar,in an eastern Mediterranean lagoon (Kaiafas,Ionian Sea)

Temporal and spatial variations of environmental and water quality parameters and their relations with macrobenthic flora were investigated in an eastern Mediterranean lagoon. Kaiafas is a mesohaline lagoon, which is influenced by point and diffused sources from the adjacent agricultural land and the nearby city. Water samples were analyzed for physicochemical parameters, microbial load and primary production, on a seasonal and spatial scale, while heavy metal concentrations were measured into two different sediment cores. An overall analysis of seasonal dynamics of water parameters and Chl-a based on trophic index TSI pointed out the lagoon as eutrophic. According to water quality parameters the lagoon was separated into two parts. The southern sector of the lagoon which was more affected by human activities showed higher nutrients, Chl-a, heavy metals and total Coliforms concentrations. Sediment texture and distribution of macrophytes were detected through the acoustic side scan sonar method, which proved to be a promising tool for defining and monitoring vegetation coverage of shallow lagoons. A number of distinct echo types and three different sediment types were revealed on the basis of the backscatter level and the variability of low and high backscatter areas. Furthermore, the extension and the coverage of Potamogeton pectinatus and Chara hispida f. corfuensis were successively depicted by combining the data of SSS and ground truthing samples. Meadows of P. pectinatus were established to the lagoon limits where high turbidity and silty substrate occurred, while C. hispida f. corfuensis was limited in deep and high transparent waters with sandy substrate.