Chemistry of chromium spinel in high-Mg rocks from the Morungava Intrusion,Cretaceous Paraná Igneous Province,southernmost Brazil

Mineralogy and Petrology - Mafic-ultramafic intrusions within continental flood basalt terrains are frequently associated with Cu-Ni-PGE mineralization. This study aims to constrain the...     

Image analysis applied to quantitative evaluation of chromatic impact generated by open-pit quarries and mines

One of the most important environmental impacts resulting from opencast mining, and especially quarries, is the visual impact. Evaluation of this impact considers two aspects: first, the area occupied by the quarry as seen by an observer from a specific place, and, second, the chromatic contrast existing between landscape and exploitation. In this study we develop a methodology to assess the chromatic impact in an objective and comparable form. To assess this impact we developed a method based on image analysis that allows us to obtain from a picture or image its equivalent as a function of chromatic impact, according to the sensibility of the human eye to different wavelengths. The methodology was applied to the Martinenca limestone quarry (Alcanar, Tarragona) and to Cerro Kori Kollo mine, La Joya district (Bolivia).     

A Neogene giant landslide in Tarapacá, northern Chile: A signal of instability of the westernmost Altiplano and palaeoseismicity effects

Giant landslides, which usually have volumes up to several tens of km³, tend to be related to mountainous reliefs such as fault scarps or thrust fronts. The western flank of the Precordillera in southern Peru and northern Chile is characterized by the presence of such mega-landslides. A good example is the Latagualla Landslide (19°15′S), composed of ~ 5.4 km³ of Miocene ignimbritic rock blocks located next to the Moquella Flexure, a structure resulting from the propagation of a west-vergent thrust blind fault that borders the Precordillera of the Central Depression. The landslide mass is very well preserved, allowing reconstitution of its movement and evolution in three main stages. The geomorphology of the landslide indicates that it preceded the incision of the present-day valleys during the late Miocene. Given the local geomorphological conditions 8–9 Ma ago (morphology, slopes and probably a high water table), large-magnitude earthquakes could have provided destabilization forces enough to cause the landslide. On the other hand, present seismic forces would not be sufficient to trigger such landslides; therefore the hazard related to them in the region is low.     

Late Quaternary vegetation and climate dynamics in central-eastern Brazil: insights from a ~35k cal a bp peat record in the Cerrado biome

The late Quaternary evolution of central-eastern Brazil has been under-researched. Questions remain as to the origin of the Cerrado, a highly endangered biome, and other types of vegetation, such as the Capões – small vegetation islands of semi-deciduous and mountain forests. We investigated the factors that influenced the expansion and contraction of the Cerrado and Capões during the late Quaternary (last ~35 ka), using a multi-proxy approach: stable isotopes (δ¹³C, δ¹⁵N), geochemistry, pollen and multivariate statistics derived from a peat core (Pinheiro mire, Serra do Espinhaço Meridional). Five major shifts in precipitation, temperature, vegetation and landscape stability occurred at different timescales. Our study revealed that changes in the South Atlantic Convergence Zone (SACZ) seem to have been coeval with these shifts: from the Late Glacial Maximum to mid-Holocene the SACZ remained near (~29.6 to ~16.5k cal a bp ) and over (~16.5 to ~6.1 k cal a bp ) the study area, providing humidity to the region. This challenges previous research which suggested that climate was drier for this time period. At present, the Capões are likely to be a remnant of a more humid climate; meanwhile, the Cerrado biome seems to have stablished in the late Holocene, after ~3.1 k cal a bp .     

Geographical distribution of Tillandsia lomas in the Atacama Desert, northern Chile

We assessed the geographic distribution of Tillandsia lomas in northern Chile, from Arica (18°20′S) to the Loa river (21°25′S) and discussed the factors that might potentially underlie the observed patterns. We carried out extensive field survey complemented with aerial surveys and analysis of specimens deposited in herbaria. We detected over 30 Tillandsia stands most of which corresponded to the species Tillandsia landbeckii and can be grouped in 10 large systems. Other two species were also detected Tillandsia marconae and Tillandsia virescens, both of which show a restricted distribution in the area. Our results provide evidence on the wide distribution of Tillandsia lomas in northern Chile and its association with fog corridors.     

Deposition of nanoparticles on school eyeglasses in urban and rural areas:A methodology for a more real assessment of the possible impacts

Because incomplete confirmation is available concerning the influential role of atmosphere contamination on conjunctivitis,myopia,asthma,and allergic rhinitis in Brazil,the focus of the present work is to explore the possible relations among atmosphere contamination and eye problems.Rather that a case study on eye diseases,by way of questionnaires supplemented by the investigation of nanoparticles(NPs)on eyeglasses,the study examines the mechanisms in which NPs and ultra-fine particles are deposited on the glasses of children up to 10 years of age in urban and rural area.The important connection between atmosphere contaminants and individual protection equipment justifies improving indoor school properties in order could protect children’s eyes,particularly in high-pollution/high-particulate areas.     

δ15N and δ13C in the Mondego estuary food web: Seasonal variation in producers and consumers

Assessments of temporal variation in stable carbon and nitrogen ratios were used to examine seasonal trends of the water column and benthic food webs in the Mondego estuary (Portugal). There was a marked seasonality in weather and water column conditions, including nutrient supply and chlorophyll concentrations. In spite of the pronounced environmental changes, we found little evidence of seasonal variation in δ¹³C and δ¹⁵N of producers and consumers in the Mondego estuary, with a few notable exceptions. Nitrogen isotope ratios in macrophytes (Zostera noltii, Ulva sp., Enteromorpha sp., and Gracilaria sp.), and in two grazers (Idotea chelipes and Lekanesphaera levii) increased during late summer, with the highest δ¹⁵N values being measured in July, during a period of elevated temperatures and drought, which may have favored high rates of denitrification and heavier δ¹⁵N values. The results suggest that stable-isotope values from macrophytes and selected grazers are useful as tracers of seasonal changes in nitrogen inputs into estuaries, and that those of consumers reflect other factors beyond seasonal variations in N and C sources.     

Assessment of failure susceptibility of soil slopes using fuzzy logic

Generally, the process of land occupation in urban areas involves spaces that are not suitable for construction. In most cases these areas are subject to landslides. Therefore it is mister the development of models to evaluate the susceptibility of occurrence of landslides in these areas. For this, Fuzzy Logic is used herein for modeling such areas where landslides are susceptible to occur and, therefore, a direct evaluation is important. The possibility of capturing the judgment and the modeling of linguistic variables are the main advantages of using Fuzzy Logic. These models are capable to capture the factors directly affecting the slope stability and also the inter-relationship amongst them. These factors were chosen by experts to whom a questionnaire was sent. Fuzzy Logic was then used to transform the linguistic variables into fuzzy number, allowing thus, the calculation of failure potential index (FPI). Herein the MAX-MIN Mamdani strategy for the inference of the rule base was used. This methodology has been applied to identify the susceptibility of landslides in a chaotic occupied urban area of Itaperuna City in northeastern of Rio de Janeiro, Brazil, where some occurrences have been reported.