Mössbauer, X-ray and Magnetic Studies of Black Sand from the Italian Mediterranean Sea

The study of natural magnetic sands is instrumental to investigate the geological aspects of their formation and of the origin of their territory. In particular, Mössbauer spectroscopy provides unique information on their iron content and on the oxidation state of iron in their mineral composition. The Italian coast on the Mediterranean Sea near Rome is known for the presence of highly magnetic black sands of volcanic origin. A study of the room temperature Mössbauer spec- trum, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetic measurements of a sample of black magnetic sand collected on the seashore of the town of Ladispoli is performed. This study reveals magnetite as main constituent with iron in both tetrahedral and octahedral sites. Minor constituents are the iron minerals hematite and ilmenite, the iron containing minerals diopsite, gossular, and allanite, as well as ubiquitous sanidine, quartz, and calcite.

Mapping material distribution in a heterogeneous sand tank by image analysis

Water flow and solute transport through soils are strongly influenced by the spatial arrangement of soil materials with different hydraulic and chemical properties. Knowing the specific or statistical arrangement of these materials is considered as a key toward improved predictions of solute transport. Our aim was to obtain two-dimensional material maps from photographs of exposed profiles. We developed a segmentation and classification procedure and applied it to the images of a very heterogeneous sand tank, which was used for a series of flow and transport experiments. The segmentation was based on thresholds of soil color, estimated from local median gray values, and of soil texture, estimated from local coefficients of variation of gray values. Important steps were the correction of inhomogeneous illumination and reflection, and the incorporation of prior knowledge in filters used to extract the image features and to smooth the results morphologically. We could check and confirm the success of our mapping by comparing the estimated with the designed sand distribution in the tank. The resulting material map was used later as input to model flow and transport through the sand tank. Similar segmentation procedures may be applied to any high-density raster data, including photographs or spectral scans of field profiles.

Combined effects of heterogeneity, anisotropy, and saturation on steady state flow and transport: A laboratory sand tank experiment

Field soils show rather different spreading behavior at different water saturations, frequently caused by layering of the soil material. We performed tracer experiments in a laboratory sand tank. Such experiments complement and help comprehension of field investigations. We estimated, by image analysis, the first two moments of small plumes traveling through a two-dimensional, heterogeneous medium with strongly anisotropic correlation structure. Three steady state regimes were analyzed. Two main conclusions were drawn. First, low saturation led to very large heterogeneity and to strong preferential flow. Thus the description of the flow paths and the prediction of the solute arrival times require, in this case, more accurate knowledge about the topological structure. Second, saturation-dependent macroscopic anisotropy is an essential element of transport in unsaturated media. For this reason, small structural soil features should be properly upscaled to give appropriate effective soil parameters to be input in transport models.

La figure de la sorcière dans la littérature du XIXe siècle (Jules Michelet, George Sand, Eliza Orzeszkowa)

The nineteenth century uncovered and analysed the tragic episodes of witch-hunting and ‘witch’ trials common in Renaissance Europe. Fascinating not only to historians, this subject also inspired men of letters who popularized the image of the witch as an old, ugly and evil person, who thus deserved her lot. Jules Michelet’s La sorcière of 1862 takes a very different approach. Simultaneously a literary and historical work, the book proved scandalous as it rehabilitated the figure of the witch, shedding favourable light on her image: it was the witch who was able to save a last spark of humanity in moments of despair; it was she who acted as comforter and healer to the people. In the context of nineteenth-century literature, certain works by female authors that focused on ‘witches,’ stand out. Whilst certain male authors (Michelet included) presented the witch as a figure from the past, who had finally perished in the 17th century, texts such as George Sand’s La petite Fadette (1848) or Eliza Orzeszkowa’s Dziurdziowie (1885), suggest that the end of witch trials did not imply an end to accusations, persecutions, and even executions of ‘witches’ – and, that in terms of culture, witchcraft or sorcery had not disappeared from the societies they knew.

Quaternary uplift rates of the Central Anatolian Plateau, Turkey: insights from cosmogenic isochron-burial nuclide dating of the Kızılırmak River terraces

The Central Anatolian Plateau (CAP) in Turkey is a relatively small plateau (300 × 400 km) with moderate average elevations of ∼1 km situated between the Pontide and Tauride orogenic mountain belts. Kızılırmak, which is the longest river (1355 km) within the borders of Turkey, flows within the CAP and slowly incises into lacustrine and volcaniclastic units before finally reaching the Black Sea. We dated the Cappadocia section of the Kızılırmak terraces in the CAP by using cosmogenic burial and isochron-burial dating methods with 10Be and 26Al as their absolute dating can provide insight into long-term incision rates, uplift and climatic changes. Terraces at 13, 20, 75 and 100 m above the current river indicate an average incision rate of 0.051 ± 0.01 mm/yr (51 ± 1 m/Ma) since ∼1.9 Ma. Using the base of a basalt fill above the modern course of the Kızılırmak, we also calculated 0.05–0.06 mm/yr mean incision and hence rock uplift rate for the last 2 Ma. Although this rate might be underestimated due to normal faulting along the valley sides, it perfectly matches our results obtained from the Kızılırmak terraces. Although up to 5–10 times slower, the Quaternary uplift of the CAP is closely related to the uplift of the northern and southern plateau margins respectively.

Uncertain Belongings. Absent mourning, burial, and post-mortem repatriations at the external border of the EU in Spain

Since the mid-1980s, migrants from North African and sub-Saharan countries have irregularly crossed the Strait of Gibraltar, in the hope of a better future for themselves and their families. Travelling in small, poorly equipped boats without experienced captains has cost the lives of myriad border crossers. Many of these bodies will never be recovered and the bereaved will never know whether their relatives and friends are alive or not. The bereaved are thus condemned to a state of not knowing and uncertainty. Exploring the junction of death and belonging, I firstly open a discussion about the enigmatic relation between a dead body and a dead person and argue for the importance of the physical presence of the body for mourning. Secondly, I show how the anonymity of dead border crossers and their uncertain belongings are generated, concealed, or rewritten. Following the story of an undertaker, I thirdly examine post-mortem border crossings. Depicting the power relations within identification processes, I outline the ambiguity of the term belonging by emphasising the constitutive significance of personal belongings such as clothes to restore a person’s identity. Reflecting on the ethical relationships which different actors (including the researcher) undertake with the deceased, I aim at gaining a better understanding of the multiple belonging of dead border crossers found on Spanish shores.

Global pulses of organic carbon burial in deep-sea sediments during glacial maxima

The burial of organic carbon in marine sediments removes carbon dioxide from the ocean–atmosphere pool, provides energy to the deep biosphere, and on geological timescales drives the oxygenation of the atmosphere. Here we quantify natural variations in the burial of organic carbon in deep-sea sediments over the last glacial cycle. Using a new data compilation of hundreds of sediment cores, we show that the accumulation rate of organic carbon in the deep sea was consistently higher (50%) during glacial maxima than during interglacials. The spatial pattern and temporal progression of the changes suggest that enhanced nutrient supply to parts of the surface ocean contributed to the glacial burial pulses, with likely additional contributions from more efficient transfer of organic matter to the deep sea and better preservation of organic matter due to reduced oxygen exposure. These results demonstrate a pronounced climate sensitivity for this global carbon cycle sink.