Biogas upgrading by cryogenic techniques

Environmental Chemistry Letters - The scarcity of fossil fuels and the worldwide pollution have led the scientific community to seek renewable energy alternatives. In particular, biogas has become...     

Educating citizens about their coastal environments: beach profiling in the Coastwatch project

The Coastwatch (CW) project is aimed at monitoring the coastline with the involvement of volunteers. Between 2003 and 2007 a beach profiling method was informally proposed to CW participants in Portugal as an extra activity to include in the surveys. Beach profiling contributes to a better understanding of coastal processes by providing quantitative information on the spatial/temporal evolution of beaches, which is crucial for coastal management. The profiling method proposed to the CW project is based on the physical principle of communicating vessels, and only requires a simple and inexpensive homemade ??profiler??. The simplicity of putting together and using the profiler, added to the arithmetic straightforwardness of data analysis, makes this method adequate for several kinds of users and for most levels of education. Eight workshops were held that included a classroom explanation of the method, the construction of a profiler, the actual profiling of a beach, and a final classroom session of data processing and graphing. About 140 participants received such training, and several among them independently undertook beach profiling. Surveyed participants found the workshop and the beach profiling method interesting and useful, and considered it a valuable tool for teaching and for management. External stakeholders (coastal managers) highlighted the importance of beach profiling data for management decisions and considered that this method produces robust data, even when carried out by volunteers. Further advantages of the application of the method, in the context of coastal management initiatives, for scientists, managers, and volunteers are discussed.     

Space for equity: socioeconomic variations in the provision of public parks in Hermosillo,Mexico

This article examines the intersection between globalisation and allocation of open public space by testing the spatial equity hypothesis in Hermosillo, Mexico, a regional city impacted directly by global processes. Availability and accessibility of public parks were examined using a geographic information system and neighbourhoods were stratified into quintiles based on socioeconomic status. Overall, the analysis shows that the amount of public park space in Hermosillo is substandard and its distribution reveals a pattern of spatial inequity affecting primarily residents of poor neighbourhoods. We argue that as the economy of the city grows increasingly integrated into global circuits, the global-to-local connection materialises in an unequal competition between globalised spaces and local public space. This, in turn, leads to further relegation of neighbourhoods that are already on the margins of urban equity regarding access to public parks. This study extends prior research conducted in developed countries to a city in a developing nation and fills a vacuum of information that potentially can contribute to a more equitable development in Hermosillo.     

Shifts of the feeding niche along the size dimension of three juvenile fish species in a tidal mudflat in southeastern Brazil

The diet of three cooccurring abundant fish species (Eucinostomus argenteus, Diapterus rhombeus and Micropogonias furnieri) and its ontogenetic changes in a mudflat area of a tropical bay in southeastern Brazil were described. The working hypothesis is that these three species shift the use of the available resources throughout their growth. Early juveniles of D. rhombeus and M. furnieri fed mainly on Cyclopoida copepods, shifting to Nematoda (D. rhombeus) and errant Polychaeta (M. furnieri) as they increased in size. In contrast, the early life stages of E. argenteus fed mainly on errant Polychaeta and Calanoida copepods, with increasing niche breadth as they grew. The relative degree of individual specialisation in resource use indicated specialism for M. furnieri and E. argenteus, and generalism for D. rhombeus. The largest intraspecific overlap was found for the smallest size classes. Niche breadth increased during ontogeny, with a higher average niche breadth at lower prey length/predator length ratios. Therefore, species-specific differences in diet across the resource gradient and increased niche breadth during ontogeny characterised the shifts of resource use, and probably account for the coexistence of these species in zones of sympatry in mudflat areas of southeastern Brazil.     

Green coconut shells applied as adsorbent for removal of toxic metal ions using fixed-bed column technology

This study applies green coconut shells as adsorbent for the removal of toxic metal ions from aqueous effluents using column adsorption. The results show that a flow rate of 2 mL/min and a bed height of 10 cm are most feasible. Furthermore, larger amounts of effluent can be treated for removal of single ions. The breakthrough curves for multiple elements gave the order of adsorption capacity: Cu⁺² > Pb⁺² > Cd⁺² > Zn⁺² > Ni⁺². Real samples arising from the electroplating industry can be efficiently handled.     

White tail markings are an indicator of quality and affect mate preference in rock sparrows

In birds, colourful and elaborate feathers are important traits in mate choice. Distinct tail white patches are present in many species of birds, but they remain little studied. Tail markings may indeed have a signal function because in many species males spread the tail offering a good view of these markings to females during courtship behaviour. Here, we investigated whether white tail spots in male rock sparrow, Petronia petronia, play a role in mate choice. In a free-living population of rock sparrows, we found a reduction in white tail spots size as the breeding season progressed due to abrasion, which was expected if tail spots act as a reliable quality indicator (i.e. a handicap). The same reduction was found under captive conditions, and males in worse condition (individuals that lost more weight) abraded a bigger part of white. This suggests that white tail markings are an indicator of male quality. In captivity, we measured female preference for males differing in white patch size in a mate choice experiment. The experimental reduction of the size of the males’ white spots resulted in a lower sexual interest by females. During courtship display, male rock sparrow shows a yellow breast patch (a carotenoid-based, sexually selected ornament) together with the white spots in the tail. The sizes of these two traits are positively correlated, but only the abraded white area in the tail correlates with a surrogate of individual quality (lost of weight). In conclusion, we can assert that the size of the white spots is preferred by female rock sparrows and it is a part of a multiple signal system.