Numerical investigation of the seakeeping behavior of a catamaran advancing in regular head waves

A numerical study was undertaken in order to assess the capability of an unsteady RANS code to predict the seakeeping characteristics of a high-speed multi-hull vessel in high sea states. Numerical analysis includes evaluation of ship motions, effects of wave steepness on ship response, catamaran natural frequency and added resistance in waves. Computations were performed for the DELFT 372 catamaran by the URANS solver CFDSHIP-Iowa V.4. The code was validated with encouraging results for high ship speeds (0.3≤Fn≤0.75) and high wave amplitudes (0.025≤Ak≤0.1). Comparison with strip theory solutions shows that the RANS method predicts ship motions with higher accuracy and allows the detection of nonlinear effects. Current computations evidence that heave peaks occur at resonance for all Fn, and reach the absolute maximum at Fn=0.75. Maximum pitch occurs at frequencies lower than resonance, for each speed, and absolute maximum occurs at medium Fn=0.6. Maximum added resistance, R_aw, was computed at Fn=0.45, which, interestingly, is near the catamaran Fn_coincidence. Overall, we found similar results as Simonsen et al. (2008) for KCS containership, though, herein, a multi-hull geometry and higher speeds were tested. Also, our results are useful to further evaluate the exciting forces and their correlation with f_e and λ/L_pp.     

Can salt marsh plants influence levels and distribution of DDTs in estuarine areas?

Sediments are depositories of toxic substances such as organochlorine pesticides and there is a global need for their removal in contaminated environments. Studies that combine contaminated sediments and phytoremediation are relatively recent and their number has been increasing. This work aimed to investigate whether salt marsh plants (sea club-rush Scirpus maritimus, sea rush Juncus maritimus and sea purslane Halimione portulacoides) can favor DDT and metabolites remediation in estuarine environment. For this purpose the levels of DDT, DDE and DDD were compared in vegetated and non-vegetated sediments from an estuary in the North of Portugal (in-situ study) and from another in the South of Portugal (ex-situ study). Results obtained both in the in-situ study, involving S. maritimus and J. maritimus, and in the ex-situ study, involving H. portulacoides, indicated that these plants did not have a significant role in DDTs removal and/or degradation. Therefore, it seems that the tested plants cannot influence levels and distribution of DDTs in estuarine areas.     

SIMULATED THERMAL ALTERATION OF STEROLS AND KETO-ALCOHOLS IN MARINE SEDIMENTS OF THE OKINAWA TROUGH

Compositional data on the sterol and alcohol fractions isolated from deep-sea marine sediments from the Okinawa Trough were obtained to determine the relative contribution from. marine and terrestrial inputs. Following extraction, the sterol plus alcohol fraction was isolated by layer chromatography, derivatized with BSTFA and then analysed by capillary GC and GC-MS. A suite of C26-C29 stenols and stanols and C30-C32 keto - alcohols were identified in the sediments. The thermal stability of the compounds in these sediments was studied by heating portions of the surface sediment in glass tubes fpr 16 hours at temperatures from 50℃ to 200℃.The C27 stanol/stenol ratio increased when temperatures went up to 175℃ , but the distribution of C30-C32 Keto - alcohols remained unaffected. At 200℃ most of the sterols and Keto - alcohols were destroyed.     

Cadomian volcanosedimentary complexes across the Ediacaran–Cambrian transition of the Eastern Pyrenees,southwestern Europe

International Journal of Earth Sciences - The volcanism hosted by the Ediacaran–Terreneuvian Canaveilles Group of the Eastern Pyrenees displays two distinct geochemical affinities: (1)...     

Reply to discussion on “Guidelines on the use of inverse velocity method as a tool for setting alarm thresholds and forecasting landslides and structure collapses” by F. Bozzano,P. Mazzanti,and S. Moretto

■■■The paper “Discussion to: Guidelines on the use of inverse velocity method as a tool for setting alarm thresholds and forecasting landslides and structure collapses by T. Carlà, E. Intrieri, F. Di Traglia, T. Nolesini, G. Gigli and N. Casagli” by Bozzano et al. brings forward new considerations on an issue of extreme concern in landslide risk management. To this day, the ability to predict catastrophic landslide failures from slope surface displacements is a problem dictated more by practical constraints rather than by theoretical uncertainties. In this sense, the development of data interpretation practices is crucial. This short reply provides a few further insights with regard to this subject, also in the context of the recently published literature.     

Characterization of acid mine drainage sources in the Iberian Pyrite Belt: base methodology for quantifying affected areas and for environmental management

The present work aims to propose a methodology for quantifying the sources of acid mine drainage (AMD) and to characterize the magnitude of the affected areas in the Iberian Pyrite Belt (SW Spain). Such an approach allows the creation of a support tool for managing land and natural resources valorization, which may be easily applied in similar mining regions. The motivation and usefulness of this work can be realized by focusing on two main emerging strategic issues: (1) water resources management, with the example of Alcolea dam that will receive water from affected areas in the Iberian Pyrite Belt; and (2) mineral resources valorization, especially, regarding copper exploration due to increasing market prices. The used methodology included the following general steps: it started with an inventory of the mines in the Iberian Pyrite Belt, followed by field cartography campaigns and finally the quantification of affected areas and contaminant discharges. The results of the present work serve to confirm and quantify the magnitude of the AMD pollution in the Pyrite Belt. A total affected area of about 4,847 ha was estimated. Taking into account this figure and combining it with the annual average precipitation (650 L/m²) results in an estimation of 31,503,680 m³/year of discharging water affected by the presence of sulphides. In this scenario, a total annual contribution of 260,056 tonnes/year was obtained for sulphates, which means more than 712 tonnes a day. In the case of arsenic, a toxic element, the total annual contribution is more than 20 tonnes, or close to 55 kg/day. Regarding copper, this economically interesting metal translates into total contributions of 10,364 tonnes/year in the generating medium. This gave more than 28 tonnes/day, which today sits at 8,200 dollars/tonne. This result suggests that solutions aimed at recovering this resource should be searched. It may represent a financial return at the same time that it would mean overcome environmental liabilities.     

An investigation of lead chromate (crocoite-PbCrO4) and other inorganic pigments in aged traffic paint samples from Hamilton,Ohio: implications for lead in the environment

Traffic paint samples collected from roads in the City of Hamilton, Butler County, OH, USA were investigated to determine whether or not pigments are hazardous and are of environmental concern. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that white and gray paint samples are dominated by calcite, rutile, anatase and quartz and blue traffic paint samples are dominated by calcite and barite. XRD and SEM indicate that most yellow traffic paints have lead chromate (crocoite-PbCrO₄) with common particle sizes that are typically 125–350 nm in length and 75–200 nm in width. Larger aggregates of several micrometers in diameter are also observed. The solubility of PbCrO₄ (1.34 × 10^?7 mol/L at 25 °C) combined with an increase in solubility with exposure to 0.05–0.25 M NaCl and CaCl₂ road treatments solutions as demonstrated by basic batch experiments likely makes PbCrO₄ from traffic paint a potential source for lead pollution in surface water and groundwater that is not fully recognized.     

Uranium-rich accessory minerals in the peraluminous and perphosphorous Belvís de Monroy pluton (Iberian Variscan belt)

The strongly peraluminous, perphosphorous (<0.85 wt% P₂O₅) and low-Ca granites from the Belvís de Monroy pluton contain the most U-rich monazite-(Ce) and xenotime known in igneous rocks. Along with these accessory minerals, P-rich zircon occurs, reaching uncommon compositions particularly in the more fractionated units of this zoned pluton. Monazite displays a wide compositional variation of UO₂ (<23.13 wt%) and ThO₂ (<19.58 wt%), positively correlated with Ca, Si, P, Y and REE. Xenotime shows a high UO₂ content (2.37–13.34 wt%) with parallel increases of LREE, Ca and Si. Zircon contains comparatively much lower UO₂ (<1.53 wt%) but high P₂O₅ (<14.91 wt%), Al₂O₃ (<6.96 wt%), FeO (<2.93 wt%) and CaO (<2.24 wt%) contents. The main mechanism of incorporating large U and Th amounts in studied monazite and U in xenotime is the cheralite-type [(Th,U)⁴⁺ + Ca²⁺ = 2(Y,REE)³⁺] substitution. Zircon requires several coupled mechanisms to charge balance the P substitution, resulting in non-stoichiometric compositions with low analytical totals. Compositional variations in the studied accessory phases indicate that the substitution mechanisms during crystal growth depend on the availability of non-formula elements. The strong P-rich character of the studied granites increases monazite crystallization, triggering a progressive impoverishment in Th and LREE in the residual melts, and consequently increasing extraordinarily the U content in monazite and xenotime. This is in marked contrast to other peraluminous (I-type or P-poor S-type) granite series. The P-rich and low-Ca peraluminous melt inhibits uraninite crystallization, so contributing to the U availability for monazite and xenotime.