Field application of calcite Dispersed Alkaline Substrate (calcite-DAS) for passive treatment of acid mine drainage with high Al and metal concentrations     

Tobias S. Rötting  Manuel A. Caraballo  José A. Serrano  Carlos Ayora  Jesús Carrera 《Applied Geochemistry》2008

Passive treatment systems are widely used for remediation of acid mine drainage (AMD), but existing designs are prone to clogging or loss of reactivity due to Al- and Fe-precipitates when treating water with high Al and heavy metal concentrations. Dispersed alkaline substrate (DAS) mixed from a fine-grained alkaline reagent (e.g. calcite sand) and a coarse inert matrix (e.g. wood chips) had shown high reactivity and good hydraulic properties in previous laboratory column tests. In the present study, DAS was tested at pilot field scale in the Iberian Pyrite Belt (SW Spain) on metal mine drainage with pH near 3.3, net acidity 1400–1650 mg/L as CaCO₃, and mean concentrations of 317 mg/L Fe (95% Fe(II)), 311 mg/L Zn, 74 mg/L Al, 20 mg/L Mn, and 1.5–0.1 mg/L Cu, Co, Ni, Cd, As and Pb. The DAS-tank removed an average of 870 mg/L net acidity as CaCO₃ (56% of inflow), 25% Fe, 93% Al, 5% Zn, 95% Cu, 99% As, 98% Pb, and 14% Cd, but no Mn, Ni or Co. Average gross drain pipe alkalinity was 181 mg/L as CaCO₃, which increased total Fe removal to 153 mg/L (48%) in subsequent sedimentation ponds. Unfortunately, the tank suffered clogging problems due to the formation of a hardpan of Al-rich precipitates. DAS lifetime could probably be increased by lowering Al-loads.  相似文献   

On the Two-body Problem with Slowly Decreasing Mass     

C. Prieto  J.A. Docobo 《Celestial Mechanics and Dynamical Astronomy》1997,68(1):53-62

We intend to present two approximate analytic solutions of the two-body problem with slowly decreasing mass which are obtained through the integration of the Hamilton equations. The law of mass variation used was m = -αn on the first case, and mi = αimin(i); i = 1,2 on the second which gives rise to a perturbed Keplerian problem dependent on one and two small parameters respectively. Practical applications are included. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Determining the drivers of long‐term aridity variability: a southern African case study          下载免费PDF全文

Manuel Chevalier  Brian M. Chase 《第四纪科学杂志》2016,31(2):143-151

This paper highlights the importance of differentiating between precipitation amount and moisture availability (‘humidity’/‘aridity’) when considering proxy records of climate change. While the terms are sometimes used interchangeably, moisture availability is determined by both (i) precipitation amount and (ii) temperature, through its influence on potential evapotranspiration. As many palaeoenvironmental proxies reflect changes in this water balance rather than purely precipitation amount, it is important to distinguish between the potential relative influences of precipitation and temperature if those records are to be interpreted in terms of climate mechanisms and/or compared with model outputs. As a case study, we explore how precipitation and temperature have determined moisture availability in South Africa's summer rainfall zone over the last 45 000 years. Using quantitative reconstructions of mean annual temperature, summer rainfall amount and an aridity index, our analysis reveals strong spatiotemporal variability in the relative influences of precipitation and temperature on aridity. Temperature is shown to have exerted a considerable and even dominant influence on moisture availability, resulting in elevated humidity during the last glacial period, despite significant reductions in precipitation amount.  相似文献   

Tithonian age of dinosaur fossils in central Patagonian,Chile: U–Pb SHRIMP geochronology     

Manuel Suárez  Rita De La Cruz  Mark Fanning  Fernando Novas  Leonardo Salgado 《International Journal of Earth Sciences》2016,105(8):2273-2284

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Hypothesis on the hydrogeological context of wetland areas and springs related to evaporitic karst aquifers (Málaga,Córdoba and Jaén provinces,Southern Spain)     

Bartolomé Andreo  José Manuel Gil-Márquez  Matías Mudarra  Luis Linares  Francisco Carrasco 《Environmental Earth Sciences》2016,75(9):759

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Comment on “Study on the reliable computation time of the numerical model using the sliding temporal correlation method”     

Antonio Algaba  Fernando Fernández-Sánchez  Manuel Merino  Alejandro J. Rodríguez-Luis 《Theoretical and Applied Climatology》2016,126(3-4):797-799

The paper, “Study on the reliable computation time of the numerical model using the sliding temporal correlation method,” was published in Theoretical and Applied Climatology. In that work, the sliding temporal correlation analysis is employed to investigate the predictable time of two typical chaotic numerical models, namely the Lorenz system and the Chen chaotic system. However, it has been recently shown by us when using a linear scaling in time and state variables that generically, the Chen system is only a particular case of the Lorenz system, with time reversion if the parameter c is positive. Consequently, to study the Chen chaotic system is simply to consider the Lorenz system integrated backwards.  相似文献   

Effectiveness of the structural fisheries policy in the European Union     

Juan C. Surís-Regueiro  Manuel M. Varela-Lafuente  Carlos Iglesias-Malvido 《Marine Policy》2003,27(6):535-544

This paper presents an analysis of the effectiveness of the community structural policy in the fisheries sector by comparing the relative level of compliance with objectives (reduction of fleets and economic viability) with the mechanisms that have been implemented (structural funds and allocation of quotas). On the one hand, this analysis shows that there is a positive correlation between the level of structural funds and the attainment of goals. On the other hand, it was found that the greater the relative availability of quotas, the poorer the countries performed in complying with the objective of reducing the fishing capacity, and the higher the expectations of achieving acceptable yields. These correlations, however, were not very strong.  相似文献   

Marine protected areas in Puerto Rico: Historical and current perspectives   总被引：1，自引：0，他引：1  

Alfonso Aguilar-Perera  Michelle Schrer  Manuel Valds-Pizzini 《Ocean & Coastal Management》2006,49(12):961-975

In Puerto Rico, the environmental legislation for establishing marine protected areas (MPAs) is complex due to its current political position with the United States (US) as not only local but also federal US laws affect designations. Historically, during the Spanish rule, mangrove forests were protected for extractive reasons (i.e., charcoal) and the first protected area was established by 1918 as an Insular Forest. Currently, of the 37 MPAs recognized and investigated in this work, the vast majority (73%) are Natural Reserves, followed by Commonwealth Forests (13.5%). Most MPAs in Puerto Rico were implemented using a top-down approach (i.e., government) which follows US federal guidelines for protecting endangered species, critical habitats, and natural and cultural resources. The development of management plans for MPAs on the island is increasingly adopting a public participatory process. However, this latter process is new for the government of Puerto Rico that has not incorporated a policy based on an Integrated Coastal Management.  相似文献   

Spatial patterns of groundfish assemblages on the continental shelf of Portugal   总被引：4，自引：1，他引：4  

Gomes  Manuel C.; Serrao  Ester; de Fatima Borges  Maria 《ICES Journal of Marine Science》2001,58(3):633-647

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Microstructure measurements in natural waters: Methodology and applications   总被引：2，自引：0，他引：2  

Elena Roget  Iossif Lozovatsky  Xavier Sanchez  Manuel Figueroa   《Progress in Oceanography》2006,70(2-4):126

Modern approaches to microstructure data processing, including wavelet denoising, are discussed. The wavelet procedure is applied to small-scale shear signals before estimating the dissipation rate ε and to the temperature/density profiles used to calculate Thorpe scales. Microstructure data obtained on the Mediterranean shelf of Catalonia are used to illustrate various approaches to the Thorpe displacement calculations. It is suggested that the Weibull probability function is an appropriate model for the Thorpe scale distribution. Microstructure measurements from the upper layer of the Boadella reservoir (Catalonia, Spain) support this finding.A new analytical approximation for the 1D Panchev–Kesich spectrum is deduced and the results of ε computation are compared with spectral fitting by the widely used Nasmyth spectrum. Applying the Kraichnan spectral model to compute ε from temperature spectra in the convective-viscous sub-range is examined as an alternative to the Batchelor spectrum. Microstructure measurements taken in Lake Banyoles (Catalonia, Spain) and in the North Atlantic were used for spectral calculations.Statistical analysis of eddy K_b and thermal K_θ diffusivities measured on a shallow shelf of the Black Sea shows the importance of process-orientated domain averaging of the diffusivities in obtaining good correspondence between K_b and K_θ in active turbulent regions. In weakly turbulent, stratified interior layers, the averaged K_b and K_θ differ significantly, which may point to the inapplicability of isotropic formulae used for ε and temperature dissipation χ_θ estimates, as well as to a dependence of the mixing efficiency γ on the Richardson number or in some cases on regions of fossil turbulence.  相似文献