Variations in the response of the dune coast of northern France to major storms as a function of available beach sediment volume

A series of airborne topographic LiDAR data were obtained from May 2008 to January 2014 over two coastal sites of northern France (Bay of Wissant and east of Dunkirk). These data were used with wind and tide gauge measurements to assess the impacts of storms on beaches and coastal dunes, and particularly of the series of major storms that hit western Europe during the fall and early winter of 2013. Our results show a high variability in shoreline response from one site to the other, but also within each coastal site. Coastal dune erosion and shoreline retreat occurred at both sites, particularly on the coast of the Bay of Wissant where shoreline retreat up to about 40 m was measured. However, stability or even shoreline advance were also observed despite the occurrence of an extreme water level with a return period >100 years during the storm Xaver in early December 2013. Comparison of shoreline change with variations of coastal dune and upper beach volumes revealed only weak relationships. Our results nevertheless showed that shoreline behavior seems to strongly depend on the initial sediment volume on the upper beach before the occurrence of the storms. According to our measurements, an upper beach volume of about 30 m³ m^?1 between the dune toe and the mean high water level is sufficient at these sites to protect the coastal dunes from storm waves associated with high water levels with return periods >10 years. The identification of such thresholds in terms of upper beach width or sediment volume may represent valuable information for improving the management of shoreline change by providing an estimate of the minimum quantity of sand on the upper beach necessary to ensure shoreline stability in this region. Copyright © 2016 John Wiley & Sons, Ltd.     

Embryotoxicity of butyltin compounds to the sea urchin Paracentrotus lividus.

Tributyltin (TBT) has been widely employed in marine anti-fouling paints as a biocide, although it represents a serious risk, particularly in estuarine and coastal water/sediment ecosystems. In this study, the embryotoxic effects of TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), were analyzed during the development of the sea urchin Paracentrotus lividus from post-fertilization to the pluteus stage, to better clarify ecotoxicological impact. The embryotoxicity of butyltins is concentration-dependent and increases proportionally with number of butyl groups. Significant growth reduction was observed at TBT concentrations as low as 0.01 microgram l-1; 1 microgram l-1 was the maximum concentration allowing embryos to reach the pluteus stage at 48 h post-fertilization. Development was blocked at the morula or blastula stage with higher TBT concentrations. DBT and MBT are less toxic: slowed development and a decrease in pluteus size occurred at 10 micrograms l-1 DBT and 0.5 mg l-1 MBT. Effects on both skeletal deposition and blocked embryonic development are suggested to be due to the interference of organotin compounds with intracellular calcium homeostasis.     

Sensitivity of near-surface Tropical Instability Waves to submonthly wind forcing in the tropical Atlantic

This study demonstrates the sensitivity of the near-surface properties in the tropical Atlantic Ocean to the high-frequency of the winds in numerical simulations. At intra-seasonal timescales (2–50 days), two distinct period ranges dominate the variability in the upper ocean: periods between 2 and 20 days, which are essentially wind-forced and periods between 20 and 50 days, due mostly to Tropical Instability Waves (TIWs). Using a numerical model forced by different wind fields, it is shown that the characteristics of the intra-seasonal variability in the ocean surface mixed-layer are strongly dependent on the wind forcing. Submonthly winds are shown to force large variability in the upper ocean that can strikingly decrease the amplitude of the TIWs in the mixed-layer and their imprint on the horizontal distribution of sea surface temperatures. Wind products containing too much energy at submonthly periods thus prevent wind-forced simulations from reproducing a realistic surface signature of TIWs, when compared to satellite observations of sea surface temperature. In addition, submonthly wind variability may be responsible for part of the observed interannual variability of the TIW signature in the temperature. The impact of submonthly winds is strongest in the mixed-layer: beneath the mixed-layer, all simulations show similar characteristics of the TIWs.     

Analytical development of the lunisolar disturbing function and the critical inclination secular resonance

We provide a detailed derivation of the analytical expansion of the lunar and solar disturbing functions. Although there exist several papers on this topic, many derivations contain mistakes in the final expansion or rather (just) in the proof, thereby necessitating a recasting and correction of the original derivation. In this work, we provide a self-consistent and definite form of the lunisolar expansion. We start with Kaula’s expansion of the disturbing function in terms of the equatorial elements of both the perturbed and perturbing bodies. Then we give a detailed proof of Lane’s expansion, in which the elements of the Moon are referred to the ecliptic plane. Using this approach the inclination of the Moon becomes nearly constant, while the argument of perihelion, the longitude of the ascending node, and the mean anomaly vary linearly with time. We make a comparison between the different expansions and we profit from such discussion to point out some mistakes in the existing literature, which might compromise the correctness of the results. As an application, we analyze the long-term motion of the highly elliptical and critically-inclined Molniya orbits subject to quadrupolar gravitational interactions. The analytical expansions presented herein are very powerful with respect to dynamical studies based on Cartesian equations, because they quickly allow for a more holistic and intuitively understandable picture of the dynamics.     

Evolution: disjunct degeneration of immunological determinants

The dissolution of calcified invertebrate skeletons releases an elaborate mixture of proteins, glycoproteins and polysaccharides. These skeletal matrix macromolecules are thought to play a major role in calcification and were widely used for phylogenetical studies. We tested the reactivity of water-soluble macromolecules from a wide range of invertebrate skeletons with two antisera raised against the shell matrix of the bivalve, Pinna nobilis. Projections of our results on the phylogenetical tree of Starobogatov (1992) show for the first time that, during evolution, antigenic determinants may degenerate in some stocks while they remain intact in others. The phylogenetic implications of these patterns of disjunct degeneration are discussed.     

Kirishites,a new type of natural high-carbon compounds

On the right-hand bank of the Volkhov River, in the natural area of tektite-like glasses (Volkhovites), fragments of shungites and slags with bunches of hairlike dark brownish enclosures were found. The filament thickness ranged from 20 to 100 μm, and separate “hairlines” were 3 cm in length. The composition of shungites and “hairlines” was found to be identical, which allowed us to consider the latter as aposhungite carbon formations. The high-carbon hairline structures associated with volkhovites are called kirishites. Kirishites are a new type of high-carbon structures that formed simultaneously with volkhovites in the case of explosion-type delivery of carbon slag and shungite fragments to the daylight surface during Holocene explosive activity. Under sharply reductive conditions, the slags partially melted, the melts were segregated, and carbonaceous-silicate and carbonaceous-ferriferous glasses formed with subsequent decompression-explosive liberation of carbon-supersaturated structures, which were extruded from shungite and slag fragments in the form of a resinoid mass. The “hairlines” were found to be zonal in structure: the central axial zones are composed of high-nitrogen hydrocarbon compounds, and peripheral regions are essentially carbonaceous with a high content of organic-mineral compounds and numerous microanomalies of petrogenic, volatile, rare, and ore elements. Infrared spectroscopy identified in kirishites proteinlike compounds, diagnosed in absorption bands (in cm⁻¹) 600–720 (Amid V), 1200–1300 (Amid III), 1480–1590 (Amid II), 1600–1700 (Amid I), 3000–3800 (vibrations in NH₂ and II groups). Gas chromatography, with the possibility of differentiation of left- and right-handed forms, revealed a broad spectrum of amino acids in kirishites, with their total content found to be the absolutely highest record for natural bitumens, an order of magnitude higher than the largest amino acid concentrations ever revealed in fibrous high-structured kerite crystals from Volyn pegmatites and in Transbaikalia phyto fulgurates. Like in phytofulgurites and fibrous kerites, in kirishites the amino acids are abiogenic, and they are predominately left-handed in configuration, contrary to the commonly accepted view about the exclusively biological nature of left-handed amino acids and their natural abiological thermofusion. Kirishites can be considered as models of prebiotic systems, predecessors of the simplest living organisms. This process could be favored by extreme conditions with rapid variations of temperature and pressure. Further study of kirishites and construction of a kirishite formation model will also be useful for development of the conception of endogenous ore-naphtobiogenesis.     

Extended time weather forecasts contributes to agricultural productivity estimates

Weather conditions in critical periods of the vegetative crop development influence crop productivity, thus being a basic parameter for crop forecast. Reliable extended period weather forecasts may contribute to improve the estimation of agricultural productivity. The production of soybean plays an important role in the Brazilian economy, because this country is ranked among the largest producers of soybeans in the world. This culture can be significantly affected by water conditions, depending on the intensity of water deficit. This work explores the role of extended period weather forecasts for estimating soybean productivity in the southern part of Brazil, Passo Fundo, and Londrina (State of Rio Grande do Sul and Paraná, respectively) in the 2005/2006 harvest. The goal was to investigate the possible contribution of precipitation forecasts as a substitute for the use of climatological data on crop forecasts. The results suggest that the use of meteorological forecasts generate more reliable productivity estimates during the growth period than those generated only through climatological information.     

Mathematical models of climate evolution in Dobrudja

The understanding of processes that occur in climate change evolution and their spatial and temporal variations are of major importance in environmental sciences. Modeling these processes is the first step in the prediction of weather change. In this context, this paper presents the results of statistical investigations of monthly and annual meteorological data collected between 1961 and 2007 in Dobrudja (a region situated in the South–East of Romania between the Black Sea and the lower Danube River) and the models obtained using time series analysis and gene expression programming. Using two fundamentally different approaches, we provide a comprehensive analysis of temperature variability in Dobrudja, which may be significant in understanding the processes that govern climate changes in the region.     

Reconstructing the spatial distribution of large vegetation formations during the mid-Holocene in Romania: a predictive modeling approach

The present study tests the usefulness of SoLIM software and GIS techniques for the reconstruction of large vegetation formations from the mid-Holocene period in Romania. We used current reference climate data (temperature, precipitation) and the current extent of ecological regions in Romania to derive climate optimality functions for each vegetation formation. The optimality functions were used to simulate current and past distributions of vegetation. The results showed that the current and mid-Holocene simulated spatial distributions of vegetation are quite similar. Changes were found for about 14% of the Romanian territory (33 946 km²), the most important being the retreat of coniferous forests in favor of mixed forests and of mixed forests in favor of forest steppe. The former is validated by previous pollen-based studies showing the transition from coniferous forests to mixed forests that occurred in several areas of the country after the mid-Holocene. The study demonstrates the potential of this methodological approach to reconstruct past vegetation formations, and at the same time that it is a straightforward and expert knowledge-based method. Although our application uses only climate factors, the results can be further refined by incorporating additional drivers (soil and landform information, site-specific pollen and fossil data, wildfire data) for a more accurate inference of paleovegetation.