Waste dump erosional landform stability – a critical issue for mountain mining

Mining is the largest producer of solid wastes which, when released to land or into waterways, can cause harmful environmental impacts. This is mostly due to fluvial erosion, which is highly increased in mountain areas, due to abrupt slopes. We have analysed this situation at a mountain watershed (192 ha), where steep mined sites and their waste dumps are the main source of sediment in a Natural Park. This problem was tackled by building gabion check dams downstream from the mined sites. We used the DEM of Differences (DoD) method to quantify erosion and sediment yield from three waste dumps (5 ha). Their topography and substrate properties were analysed to understand the erosion problem. The sediment trapped by the check dams was quantified by electrical resistivity tomography (ERT). The rainfall characteristics triggering an episode that filled the check dams with sediment in the winter 2009–2010, were studied to confirm whether it was a case of extreme precipitation conditions. The waste dumps sediment yield (353 ± 95 Mg ha^?1 yr^?1) suggests severe landform instability. Analysis of topographic and substrate properties confirmed long, steep slopes combined with highly erodible materials. The check dams proved to be inefficient in controlling sediment loads, as they had only functioned for four years of 31 of existence, having trapped 13 000 ± 660 m³ of sediment, whereas we estimated that the waste dumps have yielded approximately three times more sediment for the same period. Rainfall analyses showed that neither intense nor extreme conditions (return period of 25 to 35 years) triggered the mobilization of 37 ± 2 Mg ha^?1 in a month. This study highlights the fact that mining operations in similar mountainous settings, with equivalent waste dump construction and reclamation practices, are currently unfeasible. We conclude that landform stability cannot be achieved at this site without landform changes. Copyright © 2017 John Wiley & Sons, Ltd.     

Sonification of geophysical data through time–frequency analysis: theory and applications

In this paper, we introduce a new method of geophysical data interpretation based on simultaneous analysis of images and sounds. The final objective is to expand the interpretation workflow through multimodal (visual–audio) perception of the same information. We show how seismic data can be effectively converted into standard formats commonly used in digital music. This conversion of geophysical data into the musical domain can be done by applying appropriate time–frequency transforms. Using real data, we demonstrate that the Stockwell transform provides a very accurate and reliable conversion. Once converted into musical files, geophysical datasets can be played and interpreted by using modern computer music tools, such as sequencers. This approach is complementary and not substitutive of interpretation methods based on imaging. It can be applied not only to seismic data but also to well logs and any type of geophysical time/depth series. To show the practical implications of our integrated visual–audio method of interpretation, we discuss an application to a real seismic dataset in correspondence of an important hydrocarbon discovery.     

What can gene flow and recruitment dynamics tell us about connectivity between European hake stocks in the Eastern North Atlantic?

Systematic genetic analyses of fish populations allow the testing of temporal stability in their genetic structures and better understanding their pattern of connectivity. In this study the pattern of gene flow between the two Atlantic stocks of the European hake has been examined for the period 2000-2002. Present analyses indicate that a large genetic homogeneity existed among all Atlantic populations in that period, and that a systematic grouping occurred between Porcupine Bank samples and Cantabric ones. This scenario is congruent with an inter-annual gene flow from central grounds of the northern stock (Porcupine and Great Sole) to Iberian grounds inhabited by the southern stock. Additionally, estimated migration figures were in agreement with the good recruitments observed in the southern stock after 2003 despite the spawning biomass was at its historical minimum. Altogether these results highlight the central role of Porcupine bank and Great Sole in making sustainable both stocks and advocate the integrative management of this hake fishery by means of a multidisciplinary assessment.     

Ichnology, sequence stratigraphy and depositional evolution of an Upper Cretaceous rocky shoreline in central Chile: Bioerosion structures in a transgressed metamorphic basement

Exposures of upper Paleozoic slates of the metamorphic basement near Concepción, central Chile, are covered by transgressive deposits belonging to the Upper Cretaceous Quiriquina Formation. Presence of clusters of the bivalve boring Gastrochaenolites isp. at the irregular and erosive contact between these two units indicates the development of an ancient rocky shoreline, illustrating a rare example of bioerosion in a metamorphic substrate. Coarse-grained deposits mantling the bioeroded surface represent a transgressive lag produced due to ravinement. In sequence-stratigraphic parlance, the bioeroded surface is classified as a FS/SB or co-planar surface formed due to amalgamation of erosion during lowstand and the subsequent transgression. Unburrowed trough cross-bedded upper-shoreface to intensely bioturbated middle-shoreface deposits record continuous transgression. Logs bioeroded by Teredolites clavatus are also present. Middle-shoreface deposits are dominated by deep Ophiomorpha isp., commonly showing laminated infill. Thalassinoides suevicus occurs locally. Intense bioturbation also suggests that the shoreface developed in embayed shorelines, protected from oceanic waves. While rocky shorelines in limestone are characterized by a high abundance and diversity of bioerosion structures, those formed in other types of substrates contain less diverse, commonly monospecific, suites of borings. In terms of Seilacherian ichnofacies, the bioerosion structures analyzed are attributed to a low-diversity expression of the Trypanites ichnofacies. It is proposed that the Trypanites ichnofacies thus may display two expressions: an archetypal one characterized by high diversity in carbonate substrates, along with a depauperate expression in other types of substrates (e.g., metamorphic and igneous rocks). The extreme hardness of the substrate is regarded as the stress factor responsible for the reduction in ichnodiversity.     

Comparative study of digestion methods EPA 3050B (HNO₃--H₂O₂--HCl) and ISO 11466.3 (aqua regia) for Cu, Ni and Pb contamination assessment in marine sediments

Knowing the metal extraction capacity of a digestion method is crucial for a better environmental interpretation of metal concentrations determined in sediments. One of the main problems at the present is the lack of harmonization of information obtained by two of the most popular sediment partial digestion methods: ISO 11466.3 (aqua regia) and EPA 3050B (HNO?--H?O?--HCl). In the present work, the amount of Cu, Ni and Pb leached by using both methods was compared with the total content of those elements in marine sediments collected, as an example, from the Cienfuegos Bay, Cuba. Similar amounts of Cu were extracted by both methods; while leaching of Ni and Pb were different. Generally, the EPA method extracted more Ni than the ISO method. In contrast, Pb was extracted in a larger amount by the ISO method. Some explanations are given for the observed results. X-ray Diffraction, X-ray Fluorescence, Particle Induced X-ray Emission Spectrometry and Energy Dispersive X-ray coupled to Scanning Electron Microscopy were employed for this purpose. On the other hand, none of the methods studied extracted simultaneously the fraction of all the metals, probably provided by human activity (Theoretical Anthropogenic Fraction) in both sediments studied. The use of ISO 11466.3 or EPA 3050B is recommended since the analytical performance parameters of both, in combination with Flame Atomic Absorption Spectrometry, are adequate. For a better environmental interpretation of the analytical results, information on the extraction efficiency of the selected method for specific elements and sediments under study should also be provided, together with the determined concentrations.     

Reduction Rates of Sedimentary Mn and Fe Oxides: An Incubation Experiment with Arctic Ocean Sediments

To test the hypothesis that manganese- and iron-reducing bacteria in marine sediments respond rapidly to seasonal pulses of fresh organic carbon settling to the sea floor, we amended wet metal oxide?Crich and metal oxide?Cpoor sediments from the Beaufort Sea, Canadian Arctic, with organic carbon in the form of shrimp powder and incubated them at room temperature. Neither Mn nor Fe was released to the aqueous phase from unamended metal oxide?Crich sediment during a 41-day incubation, but both elements were released from sediment aliquots amended with organic carbon. Dissolved Mn appeared in the aqueous phase after a lag period of 2 days or less and reached levels as high as 600 ??mol l^?1 before levelling out. The release of dissolved Mn was accompanied by a decrease in the concentration of solid-phase reducible Mn. Dissolved Fe did not appear until 2 weeks into the incubation and only after the concentration of dissolved Mn had levelled out. For low concentrations of amended organic carbon (0.3%), the kinetics of Mn reduction fit a second-order rate law with a rate constant k = 2 × 10^?3 g ??mol^?1 day^?1, but at intermediate and high organic carbon concentrations (0.7 and 1.3%), the reduction kinetics was better described by a pseudo-first-order rate law with a rate constant k?? = 1.6 × 10^?1 day^?1. A pulse of organic carbon settling to the sea floor can trigger reduction of Mn and Fe oxides within a few days in strongly seasonal sedimentary environments, such as in the Arctic.     

Quantization of the universe as a black hole

It has been shown that black holes can be quantized by using Bohr’s idea of quantizing the motion of an electron inside the atom. We apply these ideas to the universe as a whole. This approach reinforces the suggestion that it may be a way to unify gravity with quantum theory.     

Creative economy and employment quality in large urban areas in Spain

The impact of the economic crisis should act as an incentive to devise less vulnerable economic development models for Spanish cities. This study confirms that the impact of the creative economy, one of the most interesting initiatives in this context, remains very limited. Furthermore, microdata obtained from a sample of one million workers in Spain, published annually by the Social Security system, confirm that the sharp contrasts emerging in employment quality between sectors and regions, the processes of ‘precariousness of talent’ and labour dualization expressed through inequalities in the occupational structure are each becoming significant threats to viable economic development. For the creative economy to be an effective instrument for metropolitan regeneration, adapted to suit the specificities of particular urban development paths, an improved understanding of the inherent complexity of creative-economy employment relations is required.     

Platform margin collapses and sequence stratigraphic organization of carbonate slopes: Cretaceous–Eocene,Gargano Promontory,southern Italy

We describe the sequence stratigraphic organization and the associated sedimentological characteristics of Cretaceous to Eocene slope and base-of-slope carbonate successions. The study area is located in the Gargano Promontory which belongs to the stable foreland of southern Italy. The succession consists of three superimposed depositional sequences separated by major unconformities. The upper two sequences are clear examples of sequence stratigraphic organization; in fact, they both start with huge megabreccia wedges (LST) followed upward by thin pelagic units (TST) and a thick package of calciturbidites and debrites that alternate with pelagic mudstone (HST). The Cretaceous highstand systems tract is clearly arranged in a number of coarsening-upward cycles while the Eocene one which also comprises a toplap shallow water unit, is not. The Gargano stratigraphic palimpsest and the entire margin of the Apulia Platform show remarkable similarities with present-day carbonate platform margins and slopes where irregular, convex-bankward embayments suggest large-scale failures. It is clear that classic sequence stratigraphic organization can result from simple platform dismantling, having no or little time relation with global sea-level fluctuations. In fact, as the margin failure (LST) interrupts the carbonate production, a period of starvation (TST) along the entire slope and base-of-slope follows necessarily. Finally, when the margin once again becomes active and productive, sediment exportation starts again and the system begins to prograde (HST).     

Thermohaline circulation sensitivity to intermediate-level anomalies

Abstract A two-dimensional Boussinesq ocean model has been used to investigate the effect of intermediate-level thermal and saline anomalies on the known multiple equilibria structure of the thermohaline circulation. These anomalies are taken as a crude representation of the Mediterranean outflow in the Atlantic Ocean. The associated perturbation drives the system towards an overturning which resembles the present average Atlantic thermohaline circulation. The sensitivity to the depth at which the anomaly is placed is also investigated. We found that near-surface anomalies are more efficient in affecting the structure of the equilibria.