Mud deposit formation on the open coast of the larger Patos Lagoon–Cassino Beach system     

S.B. Vinzon  J.C. Winterwerp  R. Nogueira  G.J. de Boer 《Continental Shelf Research》2009

This paper proposes an explanation of the mud deposits on the inner Shelf of Cassino Beach, South Brazil, by using computational modeling. These mud deposits are mainly formed by sediments delivered from Patos Lagoon, a coastal lagoon connected to the Shelf, next to Cassino Beach. The deposits are characterized by (soft) mud layers of about 1 m thick and are found between the −5 and −20 isobaths.  相似文献   

Treatment of Acid Mine Drainage (AMD) in South Brazil: Comparative active processes and water reuse     

Aline Nogueira da Silveira  Renato Silva  Jorge Rubio   《International Journal of Mineral Processing》2009,93(2):103-109

This work describes AMD techniques of neutralization, with lime, flocculation of the precipitates and comparative flocs/liquid separation by flotation with microbubbles or by lamellar settling (LS). The AMD treated water was characterized by its quality for recycling in terms of inorganic or organic elements, suspended or dissolved solids, among others. Two types of flocs were formed, “aerated” or not, in a special flocculation reactor, patented by this research group (RGF^®). Aerated flocs formed (within seconds) entered into contact with microbubbles under high shearing and raised-up at rates > 120 mh^− 1 allowing a rapid solid–liquid separation by flotation (HR-high rate), at about 13–15 m³m^− 2 h^− 1 loading capacity. Conversely, the non-aerated flocs settled at about 5–6 m h^− 1 in a lamella settler. Both AMD treatment techniques showed similar efficiencies (removal of ions > 90%) but the separation by lamella settling presented advantages, namely less reagents (no flotation collector required), lower power requirements and easier to operate. The operating costs (approximate values) of the AMD treatment by LS at pH 9 reaches about 0.3 US$ m^− 3 against 0.6 US$ m^− 3 for the HR-flotation process. Results found were proved to be similar to those found in recent ADM treatment installations in South Brazil. The quality of the treated water is fairly good, nearly free of heavy metals ion, low BOD (biological oxygen demand) and TOC (total organic content), low solids content and may be readily reused for irrigation, industrial processes and as wash water (among others, streets, vehicles, dust control). However, there is a need to extend the use of this treated water resource, but this, at least in Brazil, has not been legislated properly. It is concluded that this research will contribute in the discussion of this old and complex problem in acid mining effluents worldwide.  相似文献   

Growth and production of Pisidium amnicum in the freshwater tidal area of the River Minho estuary     

Ronaldo Sousa  Antnio J.A. Nogueira  Carlos Antunes  Lúcia Guilhermino 《Estuarine, Coastal and Shelf Science》2008,79(3):467-474

  相似文献   

The Juiz De Fora Granulite Complex of the Central Ribeira Belt, SE Brazil: A Paleoproterozoic Crustal Segment Thrust During the Pan-African Orogeny     

Monica Heilbron  Beatriz Paschoal Duarte  Jos Renato Nogueira 《Gondwana Research》1998,1(3-4):373-381

The granulites of the Juiz de Fora complex occur within thick basement thrust slices associated with the Pan-African shortening process in the central segment of the Ribeira belt. Five lithological units of the Intermediate tectonic domain of the belt can be identified on the basis of detailed geological mapping: a) orthogranulites, b) orthogneisses; c) kinzigite; d) intrusive garnet charnockite and e) amphibolite facies metasediments of probable Meso to Neoproterozoic age, correlated to the cover of the belt. Petrological data indicate high temperatures and intermediate to low lithostatic pressure conditions for the Paleoproterozoic granulite facies metamorphism. Textures and CO₂-rich fluid inclusions are probably related to an IBC path. Geochemical data do not show relevant compositional change as a result of the granulite metamorphism. Two calc-alkaline suites and tholeiitic to alkaline basic rocks can be related to compressional and extensional settings, respectively. The overall composition of the granulites, the lack of substantial LILE depletion as well as the composition of the fluid inclusion points to granulitization process driven by CO₂-rich fluids. Orthogranulites gave rise to banded gneisses as a result of the Pan-African retrograde metamorphism and intense deformation. The U and Th depletion detected in few rocks is possibly related with the hydrated conditions of the retrograde reactions.  相似文献   

Comparison of biomass and size spectra derived from optical plankton counter data and net samples: application to the assessment of mesoplankton distribution along the Northwest and North Iberian Shelf   总被引：1，自引：0，他引：1  

Nogueira  Enrique; Gonzalez-Nuevo  Gonzalo; Bode  Antonio; Varela  Manuel; Moran  Xose Anxelu G; Valdes  Luis 《ICES Journal of Marine Science》2004,61(4):508-517

  相似文献   

Prospective scenarios for water quality and ecological status in Lake Sete Cidades (Portugal): The integration of mathematical modelling in decision processes   总被引：2，自引：0，他引：2  

G. Martins  D.C. Ribeiro  D. Pacheco  J.V. Cruz  R. Cunha  V. Gonalves  R. Nogueira  A.G. Brito 《Applied Geochemistry》2008,23(8):2171-2181

The design of alternative strategies for water and ecological quality protection at the Lake Verde of Sete Cidades should be coupled with the assessment of future trophic states. Therefore, a mathematical model was developed to make prospective scenarios to reduce the risk of environmental degradation of the lake, and a modified Psenner scheme was used to characterize P distribution in the sediments. The model was able to describe thermal stratification, nutrient cycling (P, NH₄ and NO₃), dissolved O₂, and phytoplankton dynamics in the water column and adjacent sediment layers. Internal P recycling, resulting from thermal stratification and sediment anoxia, was identified as the main cause for the increase of P concentration in the hypolimnion followed by slow transfer to the epilimnion (about 20 μg/L annual average). Cyanobacteria blooms during spring were explained by the availability of P and increased water temperature verified during this season. The most sensitive model parameter was sediment porosity. This parameter has a direct effect in dissolved O₂ and P profiles and also in phytoplankton biomass. Finally, different water quality restoration scenarios were identified and their effectiveness assessed. Without the adoption of remediation measures (scenario control), Lake Verde water quality would deteriorate with annual average concentrations of total P and phytoplankton biomass (dry matter) reaching 34 μg/L and 2 mg/L, respectively, after 10 years of simulation. The reduction of P loads (scenario PORAL) into the lake would improve water quality comparatively to the scenario control, reducing the annual average concentrations of total P from 34 μg/L to 26 μg/L and of phytoplankton from 2 mg/L down to 1.4 mg/L after 10 years of simulation. In scenario sediments, corresponding to a decrease in the organic content of the sediments, a reduction in the concentrations of total P and phytoplankton is expected in the first two years of simulation, but this effect, would be attenuated throughout the years due to organic matter sedimentation. The best strategy is obtained by combining external and internal measures for P remediation. Finally, it is recommended that the model be used to integrate the results of water quality monitoring and watershed management plans.  相似文献   

Quaternary fault kinematics and chronology in intraplate northeastern Brazil     

Francisco C. Nogueira  Francisco H.R. Bezerra  Reinhardt A. Fuck 《Journal of Geodynamics》2010,49(2):79-91

Northeastern Brazil has experienced earthquake swarms, which include events up to m_b = 5.2 in the last 30 years. Ground-rupturing events, however, have not been reported in the last 200 years. We have used a multidisciplinary approach to describe the geometry, kinematics, age, paleostress field, and paleoseismological significance of ground ruptures filled by clastic sediments in the region. Methods included GIS- and remote sensing-assisted structural mapping, borehole and resistivity sounding, grain size and X-ray analysis, and Optically Stimulated Luminescence (OSL) and Single-Aliquot Regenerative-Dose (SAR) chronology. Sediment-filled faults concentrate on the hanging wall of the Jundiaí fault, a 35 km long, NE-trending, late Cretaceous to Quaternary fault. These sediment-filled faults cut across Precambrian granites and overlying alluvial and colluvial deposits and exhibit steeply planar geometry. The largest faults exhibit sediment fills that extend downward to at least 20 m. The faults alternate between normal and right-oblique normal slip, which allowed the gravitational influx of unlithified gravels to gravelly sediments into the granites. Field evidence indicates seismogenic origin associated with multistage opening and infilling. On the basis of OSL and SAR chronology, we distinguish six generations of infills, which represent the main periods of fault activity: 8.0–9.0, 11.0–15.0, 16.0–24.0, 37.0–45.5, 65.0–67.9, and 84.5–93.5 ka. These dates suggest a 15.8 ka recurrence period. A few OSL dates may represent maximum ages due to poor bleaching of sediments, which implies that the recurrence period may be underestimated. We conclude that the Jundiaí fault has been continuously active in respect of surface-rupturing during at least the last ～100 ka. The size of the surface ruptures is consistent with earthquake magnitude M ～ 5.3, close to magnitudes observed in northeastern Brazil in the short instrumental and historical record. We suggest that seismogenic-fault recurrence in intraplate settings is longer than human settlement and should be assessed by multidisciplinary methods, mainly those that provide subsurface data and chronology of clastic sediments. Faults that trap sediments during movements are ideal places for these studies. The structures we describe here may have analogs in both modern and ancient intraplate settings.  相似文献   

An evaluation of trace metal distribution, enrichment factors and risk in sediments of a coastal lagoon (Ria de Aveiro, Portugal)   总被引：1，自引：1，他引：0  

M. Ramiro Pastorinho  Trevor C. Telfer  António J. A. Nogueira  Amadeu M. V. M. Soares  James F. Ranville 《Environmental Earth Sciences》2012,67(7):2043-2052

This paper describes a sediment survey undertaken to unravel patterns of distribution and dispersion of trace metals in an Iberian Peninsula northwestern coastal lagoon (Ria de Aveiro). Cadmium, lead, chromium, copper and zinc were analyzed in bottom sediments. Geochemical normalization is performed and two different regression models for each metal versus aluminum are tested and compared using the respective enrichment factors (EF), an estimation of the relative importance of anthropogenic contributions to the studied sediments. Mean sediment quality guideline quotients (mSQGQ) are used to evaluate sediment quality and associated potential risk to biota with effects range low as empirical sediment quality guideline (SQG) in the basis for mSQGQ calculation. Additionally, the geoaccumulation index is calculated to compare studied sediment levels to global baseline levels. The application of SQGs revealed insufficient characterization capability, especially when contrasted to EF calculated from the regression methods. These pointed a mildly enriched system with localized ??hot spot?? areas. Therefore, it can be considered that bottom sediments in the Ria de Aveiro system are in their majority unpolluted, zinc being the only metal of concern, presenting enrichment in all four main channels. The major rivers outlets (Caster, Antu?, and Vouga) constitute point sources, thus presenting potential risk for biota. Yet, the strong tidal influence creates a damping effect by efficiently redistributing sediment bound metals.  相似文献   

Grain-size end-members and environmentally sensitive grain-size components: A comparative study in the mud shelf depocenters off southern Brazil     

Michel Michaelovitch de Mahiques  Samara Cazzoli y Goya  Maria Carolina da Silva Nogueira de Matos  Rodrigo Augusto Udenal de Oliveira  Bianca Sung Mi Kim  Paulo Alves de Lima Ferreira  Rubens Cesar Lopes Figueira  Marcia Caruso Bícego 《国际泥沙研究》2021,36(2):317-327

The current study aims to do a comparative analysis of the results obtained with two End-Member(EM)grain-size modeling techniques(AnalySize and BasEMMA)and the Environmental Sensitive Grain-Size(ESGS)modeling for sediment samples collected in the mudbelts of the southern Brazilian shelf.The methods were compared using grain-size data from the south Brazilian shelf,and the results are discussed here.It is the first time that the concept of ESGS,in its present form,is utilized outside China.The results show that despite its relative ease of use,the ESGS is not fully comparable to the EM analyses,and only two grain-size ESGS classes were recognized as analogous to EMs.The comparison of the AnalySize and BasEMMA procedures also revealed significant differences between the techniques.A comparative analysis between the two EM techniques revealed advantages in the BasEMMA,especially in the better correlation of the end-members with the original grain size distribution.The analysis of the geographical distribution of the EM abundances allowed point sources of sandy populations to be recognized as well as the contribution of the Rio de la Plata as a source of silty sediments to be inferred.  相似文献   

Effect of vegetation on the performance of horizontal subsurface flow constructed wetlands with lightweight expanded clay aggregates   总被引：1，自引：1，他引：0  

M. C. Mesquita  A. Albuquerque  L. Amaral  R. Nogueira 《International Journal of Environmental Science and Technology》2013,10(3):433-442

This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m^?2 day^?1. The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.  相似文献