Regulatory structures and operational environment in the Portuguese waste sector

This research computes the influence of the operational environment on the efficiency of the Portuguese urban solid waste services. A sample of 29 solid waste utilities encompassing the whole continental country was used for this purpose. Particularly, we apply the non-parametric double bootstrap model to estimate the effect of various explanatory factors on robust data envelopment analysis estimates. In general, we find a significant influence of the environmental context on the solid waste utilities’ performance. The environmental context is characterized by gross domestic product per capita, distance to treatment facilities, population density, regulation, type of management, composting and incineration services.     

Population structure and connectivity of the European conger eel (Conger conger) across the north-eastern Atlantic and western Mediterranean: integrating molecular and otolith elemental approaches

Genetic variation (mtDNA) of the European conger eel, Conger conger, was compared across five locations in the north-eastern Atlantic (Madeira, Azores, South Portugal, North Portugal and Ireland) and one location in the western Mediterranean (Mallorca). Genetic diversity of conger eel was high, and differentiation among regions was not significant. Additionally, comparisons of element:Ca ratios (Sr:Ca, Ba:Ca, Mn:Ca and Mg:Ca) in otolith cores (larval phase) and edges (3?months prior to capture) among the Azores, North Portugal, Madeira and Mallorca regions for 2?years indicated that variation among regions were greater for edges than cores. Therefore, while benthic conger may display residency at regional scales, recruitment may not necessarily be derived from local spawning and larval retention. Furthermore, data from otoliths suggest a separated replenishment source for western Mediterranean and NE Atlantic stocks. The combination of genetics and otolith chemistry suggests?a population model for conger eel involving a broad-scale dispersal of larvae, with limited connectivity for benthic juvenile life stages at large spatial scales, although the existence of one or multiple spawning grounds for the species remains uncertain.     

Evaluation of Cyto- and Genotoxicity of Poly(lactide-co-glycolide) Nanoparticles

This work reports on an analysis of the cyto- and genotoxicity of poly(lactide-co-glycolide) polymer nanoparticles, in an attempt to evaluate their mutagenic effects. Fibroblast (3T3) and human lymphocyte cell cultures were exposed to solutions containing three different concentrations of nanoparticles (5.4, 54 and 540 μg/mL, polymer mass/volume of solution). The nanoparticles were characterized in terms of their hydrodynamic diameters, zeta potentials and polydispersity indices. The morphology of the particles was determined by atomic force microscopy. The PLGA nanospheres presented a size of 95 nm, a zeta potential of −20 mV and a spherical morphology. Cellular viability assays using fibroblast cells showed no significant alterations compared with the negative control. A cytogenetic analysis of human lymphocyte cells showed no significant changes in the mitotic index in relation to the control, indicating that in the concentration range tested, the particles used in the experimental models did not present cyto- or genotoxicity. For the tests conducted in this work we can conclude that biodegradable and biocompatible PLGA nanospheres are not toxic in the cell cultures tested (fibroblast and lymphocyte cells) and in the range of concentrations employed. The results provide new information concerning the toxic effects of particles produced using PLGA.     

Methane production potential from anaerobic digestion of plant biomass residues and food waste as substrates

Journal of Material Cycles and Waste Management - This research aimed to evaluate the production of biogas from anaerobic digestion (AD) using swine manure inoculum associated with different...     

Effects of activated sludge and UV disinfection processes on the bacterial community and antibiotic resistance profile in a municipal wastewater treatment plant

Environmental Science and Pollution Research - Wastewater tertiary treatment has been pointed out as an effective alternative for reducing the concentration of antibiotic resistant bacteria and...     

Seasonal variations in sugar contents and microbial community in a ryegrass soil

The relationship among sugar concentrations, microbial community and physical variables (precipitation and soil temperature) was investigated in a ryegrass soil from January 2004 to January 2005. Mono- and disaccharide sugars were extracted using a mixture of dichloromethane and methanol and analyzed as their TMS derivatives by GC-MS. Changes in microbial community were assessed using phospholipid and neutral lipid fatty acids (PLFA and NLFA, respectively) analysis. The results of a one-year study showed that the seasonal variability of sugar contents found in the soil samples is mainly related to biomass or nutritional status of the fungal community. The increase in sucrose and fructose exudation by plant roots in the beginning of the growing season (early spring) may be responsible for the highest fungal biomass amount (PLFAs) observed in this study. Fungal storage lipid abundances (NLFAs) peaked in summer, during the same period that the highest concentrations of mannitol and trehalose were detected. This is consistent with these two sugars being stress-induced fungal metabolites, produced due to the low soil moisture observed during this season. In contrast, bacterial community growth seems to be more dependent on plant substrate than on physical variables, since the strongest decrease in bacterial biomass amounts (PLFAs) was found after cutting of the ryegrass field in early July.