Mineralogical and geochemical spatial analyses of a waste-rock dump at the Libiola Fe–Cu sulphide mine (Eastern Liguria,Italy)

In this work, we investigated a 3 ha sulphide-bearing waste-rock dump (Libiola Mine, Italy) using mineralogical, geochemical, and geostatistical analyses. The dumped materials were highly heterogeneous in grain size and lithology and varied both laterally and vertically. Other than the host rock of the ore, basalts and serpentinites, the dumped materials contained high amounts of low-grade chalcopyrite- and pyrite-rich mineralisations. Due to these characteristics and to the absence of minerals able to neutralise acidity, this waste-rock dump can be classified as an acid mine drainage (AMD) producer. The study confirms that AMD is still active and, in the best scenario, can persist for up to 6.17 × 10³ years. The consequences of this process are of serious environmental concern as it involves strong acidification of the circulating waters, the release of potentially toxic metals into the soil, streams and rivers and the precipitation of huge quantities of secondary Fe-oxides and Fe-oxyhydroxides.     

Sr and Nd isotopic geochemistry of the early ultramafic–mafic rocks of the Mako bimodal volcanic belt of the Kedougou–Kenieba inlier (Senegal)

The Mako bimodal volcanic belt of the Kédougou–Kéniéba inlier is composed of volcanic basalts and peridotites interbedded by quartzites and limestones intruded by different generations of granitoïds. The early volcanic episode of the belt is constituted of submarine basalts with peridotite similar to those of the oceanic abyssal plains. It is intruded by the Badon Kakadian TTG?granitic batholite dated around 2200 Ma. The second volcanic phase is constituted of basaltic, andesitic, and felsitic flows exhibit structures of aerial volcanic rocks. It is intruded by granites dated between 2160 and 2070 Ma. The general pattern of trace element variation of submarine volcanic rocks is consistent with those of basalts from oceanic plateaus which are the modern equivalent of the Archean greenstones belts. The Nd and Sr isotopic systematics typical of juvenile material indicates that the source of these igneous rocks is derived from a depleted mantle source. These results are consistent with the idea of a major accretion within the West African Craton occurring at about 2.1 Ga and corresponding to an important process of mantle–oceanic lithosphere differentiation.     

Are assemblages of the fireworm Hermodice carunculata enhanced in sediments beneath offshore fish cages?

Abundances of the fireworm Hermodice carunculata were counted through a monitoring assessment study of fish cages in Barranco Hondo（NE Tenerife）. Seven campaigns were conducted from November 2007 to June 2010 and temporal variations were found, as well as differences among sampling stations. The polychaete H. carunculata obtained its highest abundance in sediments beneath fish cages throughout the study period. Thus, the assemblages of this omnivorous species were favoured by the presence of fish cages.     

Trends in Canadian Short‐Duration Extreme Rainfall: Including an Intensity–Duration–Frequency Perspective

Short-duration (5 minutes to 24 hours) rainfall extremes are important for a number of purposes, including engineering infrastructure design, because they represent the different meteorological scales of extreme rainfall events. Both single location and regional analyses of the changes in short-duration extreme rainfall amounts across Canada, as observed by tipping bucket rain gauges from 1965 to 2005, are presented. The single station analysis shows a general lack of a detectable trend signal, at the 5% significance level, because of the large variability and the relatively short period of record of the extreme short-duration rainfall amounts. The single station 30-minute to 24-hour durations show that, on average, 4% of the total number of stations have statistically significant increasing amounts of rainfall, whereas 1.6% of the cases have significantly decreasing amounts. However, regional spatial patterns are apparent in the single station trend results. Thus, for the same durations regional trends are presented by grouping the single station trend statistics across Canada. This regional trend analysis shows that at least two-thirds of the regions across Canada have increasing trends in extreme rainfall amounts, with up to 33% being significant (depending on location and duration). Both the southwest and the east (Newfoundland) coastal regions generally show significant increasing regional trends for 1- and 2-hour extreme rainfall durations. For the shortest durations of 5–15 minutes, the general overall regional trends in the extreme amounts are more variable, with increasing and decreasing trends occurring with similar frequency; however, there is no evidence of statistically significant decreasing regional trends in extreme rainfall amounts. The decreasing regional trends for the 5- to 15-minute duration amounts tend to be located in the St. Lawrence region of southern Quebec and in the Atlantic provinces. Additional analysis using criteria specified for traditional water management practice (e.g., Intensity-Duration-Frequency (IDF)) shows that fewer than 5.6% and 3.4% of the stations have significant increasing and decreasing trends, respectively, in extreme annual maximum single location observation amounts. This indicates that at most locations across Canada the traditional single station IDF assumption that historical extreme rainfall observations are stationary (in terms of the mean) over the period of record for an individual station is not violated. However, the trend information is still useful complementary information that can be considered for water management purposes, especially in terms of regional analysis.     

Experimental investigation on shear strength and permeability of a deeply dewatered sewage sludge for use in landfill covers

This paper presents an experimental study on a deeply dewatered sewage sludge produced by using a new technique of membrane filter press. The experiments involve measurements of sludge composition, basic physical properties, shear strength, water permeability, and leaching toxicity. The measurements of shear strength and permeability were also performed on the sludge specimens soaked in a low acid leachate or distilled water for 1 and 2 months. This is to investigate the influence of chemical change in pore fluid as a result of rainfall infiltration or leachate seepage at landfills. Comparison tests were also carried out on silty clay that is commonly used for landfill cover material. The experimental results show that the deeply dewatered sludge contains 66 % organic content and 85 % water content (dry mass basis). The undrained shear strength of the sludge is >25 kPa even after 2-month soaking in the leachate and distilled water, meeting the requirement of the Chinese standard [CJ/T249-2007, Disposal of sludge from municipal wastewater treatment plant: sludge quality for co-landfilling. Ministry of Building and Construction, P.R. China (in Chinese), 2007]. The measured cohesion and friction angle for the sludge are >20 kPa and 22.3°, respectively. The soaking of sludge specimens in either leachate or distilled water resulted in an increase in frictional angle by several degrees. The water permeability for the sludge ranges from 0.68 × 10^?8 to 1.3 × 10^?8 cm/s, and permeability after 2-month soaking is less than the minimum requirement for the barrier layer of landfill covers (i.e., 1.0 × 10^?7 cm/s). The concentrations of heavy metals leaching from the dewatered sludge are lower than the limit values of leaching toxicity for the wastewater discharge standard of China. The experimental results indicate that deeply dewatered sludge can be used as an alternative material for the barrier layer of landfill covers.     

Monitoring of heat transmission from buildings into geological environment and evaluation of soil deformation consequences in foundation engineering

In engineering geology a number of factors affecting foundation conditions are taken into consideration during engineering-geological investigations. This article deals with the factor of heat sourced from a structure (brick kiln) as a restrictive factor in foundation engineering in clay soils and introduces a documentation of soil deformation observations as an impact of the heat transmission into the geological environment. It was carried out in Southern Moravia in the Czech Republic, where the dominant foundation soils are Neogeneous clays where differential settlements of a tunnel kiln structure occurred as a result of ignoring the boundary conditions of temperature changes in the soil environment. The brick kilns caused heterogeneous spatial changes in the subsoil temperatures. This consequently resulted in differential settlements due to temperature changes originating from the kilns. The differential settlements reached as much as 150 mm. The major objective of the article is to highlight the importance of the heat transmission from buildings into the geological environment as a factor which should be considered in engineering geology and its application in planning. A new procedure for reducing or elimination of ground movements sourced from underlying clayey soils depending on the heat changes was also suggested in this context.     

Temporal evolution and compositional signatures of two supervolcanic systems recorded in zircons from Mangakino volcanic centre,New Zealand

Mangakino, the oldest rhyolitic caldera centre delineated in the Taupo Volcanic Zone of New Zealand, generated two very large (super-sized) ignimbrite eruptions, the 1.21 ± 0.04 Ma >500 km³ Ongatiti and ~1.0 Ma ~1,200 km³ Kidnappers events, the latter of which was followed after a short period of erosion by the ~200 km³ Rocky Hill eruption. We present U/Pb ages and trace-element analyses on zircons from pumice clasts from these three eruptions by Secondary Ion Mass Spectrometry (SIMS) using SHRIMP-RG instruments to illustrate the evolution of the respective magmatic systems. U–Pb age spectra from the Ongatiti imply growth of the magmatic system over ~250 kyr, with a peak of crystallisation around 1.32 Ma, ~100 kyr prior to eruption. The zircons are inferred to have then remained stable in a mush with little crystallisation and/or dissolution before later rejuvenation of the system at the lead-in to eruption. The paired Kidnappers and Rocky Hill eruptions have U–Pb zircon ages and geochemical signatures that suggest they were products of a common system grown over ~200 kyr. The Kidnappers and Rocky Hill samples show similar weakly bimodal age spectra, with peaks at 1.1 and 1.0 Ma, suggesting that an inherited antecrystic population was augmented by crystals grown at ages within uncertainty of the eruption age. In the Kidnappers, this younger age peak is dominantly seen in needle-shaped low U grains with aspect ratios of up to 18. In all three deposits, zircon cores show larger ranges and higher absolute concentrations of trace elements than zircon rims, consistent with zircon crystallisation from evolving melts undergoing crystal fractionation involving plagioclase and amphibole. Abundances and ratios of many trace elements frequently show variations between different sectors within single grains, even where there is no visible sector zoning in cathodoluminescence (CL) imaging. Substitution mechanisms, as reflected in the molar (Sc + Y + REE³⁺)/P ratio, differ in the same growth zone between the sides (along a-axis and b-axis: values approaching 1.0) and tips (c-axis: values between 1.5 and 5.0) of single crystals. These observations have implications for the use of zircons for tracking magmatic processes, particularly in techniques where CL zonation within crystals is not assessed and small analytical spot sizes cannot be achieved. These observations also limit applicability of the widely used Ti-in-zircon thermometer. The age spectra for the Ongatiti and Kidnappers/Rocky Hill samples indicate that both magmatic systems were newly built in the time-breaks after respective previous large eruptions from Mangakino. Trace element variations defining three-component mixing suggest that zircons, sourced from multiple melts, contributed to the population in each system.     

Paleolithic vs. Epipaleolithic fisheries in northern Iberia

A comparison of Paleolithic and Epipaleolithic fisheries in NW Iberia shows an overall high trophic level of catch. Freshwater fisheries (and thus their impacts) are ca. 8000 yr older than marine fisheries and have suffered virtually no changes in the region except for the increase in numbers, being focused on two families (Salmonidae, and Anguillidae to a very minor extent). Marine fisheries in the Paleolithic likely had a low impact but rapidly increased in importance, raising the average trophic level of the catch, the number of affected taxa and the proportion of marine to freshwater fisheries with time.     

Observation of high-frequency sound propagation in shallow waterwith bubbles due to storm and surf

An experiment was performed off the shore of Panama City, FL, to measure the spatial and temporal coherence of high-frequency signals that were transmitted between fixed towers. Transmission was along paths at mid depths in about 10 m of water. During the time of the experiment, there were two stormy days with breaking waves and nearby high surf. It was observed that pulse-to-pulse variations (over seconds) in travel times, over a range of frequencies, increased dramatically from those observed on quiet days. Average travel times also increased by about 3%. Dispersion was also observed. The distance between the source and the receiver towers was approximately 60 m. By assuming that bubbles were either generated by breaking waves and advected down ward and/or generated by surf and advected outward, these results are explained. Estimates of the average bubble density and bubble-density variations are made