Land Use History and Site Formation Processes at the Punic Site of Pauli Stincus in West Central Sardinia

The site of Pauli Stincus is located near the town of Terralba, on the inland shores of the Gulf of Oristano in west central Sardinia, Italy, and was occupied between the mid‐4th and the late 2nd century B.C. The site and its surroundings were the object of a joint archaeopedological and geomorphological study, which complemented the data from archaeological excavations. This study allowed us to evaluate the suitability of the different landscape and soil components for crop production in the Punic period. The discovery of a buried plow soil at the site's edge enabled us to identify a set of agricultural practices carried out by Punic farmers. These included the removal of sandy topsoil to cultivate deeper horizons enriched in illuvial clay, the use of a "sodbuster" or "rip ard," and the periodic burning of weeds, stubble, and other harvesting residues. The present study helped us to better understand the formation processes of the archaeological record at Pauli Stincus. Large quantities of allochtonous calcareous material were imported to the site from wet areas closer to the coast in order to produce earth‐based construction material, such as bricks and daub. © 2013 Wiley Periodicals, Inc.     

Dissolution of arsenopyrite (FeAsS) and galena (PbS) in the presence of desferrioxamine-B at pH 5

Microorganisms and higher plants produce biogenic ligands, such as siderophores, to mobilize Fe that otherwise would be unavailable. In this paper, we study the stability of arsenopyrite (FeAsS), one of the most important natural sources of arsenic on Earth, in the presence of desferrioxamine (DFO-B), a common siderophore ligand, at pH 5. Arsenopyrite specimens from mines in Panasqueira, Portugal (100-149 μm) that contained incrustations of Pb, corresponding to elemental Pb as determined by scanning electron microscopy-electron diffraction spectroscopy (SEM-EDX), were used for this study. Batch dissolution experiments of arsenopyrite (1 g L⁻¹) in the presence of 200 μM DFO-B at initial pH (pH₀) 5 were conducted for 110 h. In the presence of DFO-B, release of Fe, As, and Pb showed positive trends with time; less dependency was observed for the release of Fe, As, and Pb in the presence of only water under similar experimental conditions. Detected concentrations of soluble Fe, As, and Pb in suspensions containing only water were found to be ca. 0.09 ± 0.004, 0.15 ± 0.003, and 0.01 ± 0.01 ppm, respectively. In contrast, concentrations of soluble Fe, As, and Pb in suspensions containing DFO-B were found to be 0.4 ± 0.006, 0.27 ± 0.009, and 0.14 ± 0.005 ppm, respectively. Notably, the effectiveness of DFO-B for releasing Pb was ca. 10 times higher than that for releasing Fe. These results cannot be accounted for by thermodynamic considerations, namely, by size-to-charge ratio considerations of metal complexation by DFO-B. As determined by SEM-EDX, elemental sample enrichment analysis supports the idea that the Fe-S subunit bond energy is limiting for Fe release. Likely, the mechanism(s) of dissolution for Pb incrustations is independent and occurs concurrently to that for Fe and As. Our results show that dissolution of arsenopyrite leads to precipitation of elemental sulfur, and is consistent with a non-enzymatic mineral dissolution pathway. Finally, speciation analyses for As indicate variability in the As(III)/As(V) ratio with time, regardless of the presence of DFO-B or water. At reaction times <30 h, As(V) concentrations were found to be 50-70%, regardless of the presence of DFO-B. These results are interpreted to indicate that transformations of As are not imposed by ligand-mediated mechanisms. Experiments were also conducted to study the dissolution behavior of galena (PbS) in the presence of 200 μM at pH₀ 5. Results show that, unlike arsenopyrite, the dissolution behavior of galena shows coupled increases in pH with decreases in metal solubility at t > 80 h. Oxidative dissolution mechanisms conveying sulfur oxidation bring about the production of {H⁺}. However, dissolution data trends for arsenopyrite and galena indicate {H⁺} consumption. It is plausible that the formation of Pb species is dependent on {H⁺} and {OH⁻}, namely, stable surface hydroxyl complexes of the form (pH₅₀ 5.8) and for pH values 5.8 or above.     

Assessment of the physico-mechanical behaviour of gypsum-lime repair mortars as a function of curing time

Gypsum-based mortars were widely used during the Mudejar artistic period in Spain from the 12th to 16th century. During restoration works, compatibility between the new repair mortars and the original components is essential for an adequate intervention on the monument. The increasing interest of knowing the properties of the gypsum-lime-based mortars for restoration purposes justifies the research carried out. Different mortars compatible with traditional building materials were elaborated by varying the binder proportions, the type of aggregates, the binder/aggregate ratios and the curing time. The main goal of this paper is to characterize the mechanical behaviour and the pore structure of the mortars as a function of curing time. The influence between the different variables used to prepare the mortars and the development of the carbonation process over time is also considered. Mechanical strength and porosity measurements as well as X-ray diffraction and thermal analysis were performed after curing times of 1, 28 and 90 days. The results obtained confirmed a progressive increase in mechanical strength linked to the carbonation of the mortars prepared. Less lime binder and also aggregate contents showed the highest rise in strength over time, related to the highest initial porosity which favoured the carbon dioxide flow. The use of siliceous aggregates (GL-QS mortars) obtained the best results in the development of physico-mechanical properties over curing time. The knowledge obtained from the studied mortars provides practical information to establish a suitable mortar mixture for restoration works on historic buildings and modern architecture where gypsum-lime-based mortars are used.     

Geoarchaeological study of the Phoenician cemetery of Tyre‐Al Bass (Lebanon) and geomorphological evolution of a tombolo

The geoarchaeological record of the Phoenician necropolis of Al Bass (Lebanon) provides information concerning the geomorphological evolution of a late Holocene tombolo. Physical and chemical analysis of sediments indicates that the cemetery (9th century B.C.) was located near a littoral lagoon, between the dunes of a cuspate spit pointing toward the island of Tyre. From the sea apex of this spit, the moles mentioned in historical chronicles were constructed. Once mainland and island were connected, at the northern coast (where the port of Sidon was located), a sediment trap was formed, which quickly filled with silt. Afterwards, an extensive field of sand dunes buried all the archaeological remains from Phoenician to Roman times. © 2008 Wiley Periodicals, Inc.     

An approach for valid covariance estimation via the Fourier series

The use of kriging for construction of prediction or risk maps requires estimating the dependence structure of the random process, which can be addressed through the approximation of the covariance function. The nonparametric estimators used for the latter aim are not necessarily valid to solve the kriging system, since the positive-definiteness condition of the covariance estimator typically fails. The usage of a parametric covariance instead may be attractive at first because of its simplicity, although it may be affected by misspecification. An alternative is suggested in this paper to obtain a valid covariance from a nonparametric estimator through the Fourier series tool, which involves two issues: estimation of the Fourier coefficients and selection of the truncation point to determine the number of terms in the Fourier expansion. Numerical studies for simulated data have been conducted to illustrate the performance of this approach. In addition, an application to a real environmental data set is included, related to the presence of nitrate in groundwater in Beja District (Portugal), so that pollution maps of the region are generated by solving the kriging equations with the use of the Fourier series estimates of the covariance.     

Lateglacial and Holocene palaeohydrology in the western Mediterranean region: The Lake Estanya record (NE Spain)

The multi-proxy analysis of sediment cores recovered in karstic Lake Estanya (42°02′ N, 0°32′ E; 670 m a. s. l., NE Spain), located in the transitional area between the humid Pyrenees and the semi-arid Central Ebro Basin, provides the first high-resolution, continuous sedimentary record in the region, extending back the last 21 000 years. The integration of sedimentary facies, elemental and isotopical geochemistry and biogenic silica, together with a robust age model based on 17 AMS radiocarbon dates, enables precise reconstruction of the main hydrological and environmental changes in the region during the last deglaciation.Arid conditions, represented by shallow lake levels, predominantly saline waters and reduced organic productivity occurred throughout the last glacial maximum (21–18 cal kyrs BP) and the lateglacial, reaching their maximum intensity during the period 18–14.5 cal kyrs BP (including Heinrich event 1) and the Younger Dryas (12.9–11.6 cal kyrs BP). Less saline conditions characterized the 14.5–12.6 cal kyrs BP period, suggesting higher effective moisture during the Bölling/Allerød. The onset of more humid conditions started at 9.4 cal kyrs, indicating a delayed hydrological response to the onset of the Holocene which is also documented in several sites of the Mediterranean Basin. Higher, although fluctuating, Holocene lake levels were punctuated by a mid Holocene arid period between 4.8 and 4.0 cal kyrs BP. A major lake-level rise occurred at 1.2 cal kyrs BP, conducive to the establishment of conditions similar to the present and interrupted by a last major water level drop, occurring around 800 cal yrs BP, which coincides with the Medieval Climate Anomaly.The main hydrological stages in Lake Estanya are in phase with most Western Mediterranean and North Atlantic continental and marine records, but our results also show similarities with other Iberian and northern African reconstructions, emphasizing peculiarities of palaeohydrological evolution of the Iberian Peninsula during the last deglaciation.     

A rootless suture and the loss of the roots of a mountain chain: The Variscan belt of NW Iberia

Ophiolites of different Paleozoic ages occur in North-West (NW) Iberia in a rootless suture representing the remnants of the Rheic Ocean. Associated allochthonous terranes in the hanging- and foot-walls of the suture derive from the former margins, whereas the relative autochthon corresponds to the Paleozoic passive margin of northern Gondwana. The Paleozoic tectonic evolution of this part of the circum-Atlantic region is deduced from the stratigraphical, petrological, structural and metamorphic evolution of the different units and their ages. The tectonic reconstruction covers from Cambro-Ordovician continental rifting and the opening of the Rheic Ocean to its Middle to Upper Devonian closure. Then, the Variscan Laurussia–Gondwana convergence and collision is briefly described, from its onset to the late stages of collapse associated with the demise of the orogenic roots.