Heavy metal accumulation in Halimione portulacoides: intra- and extra-cellular metal binding sites

Salt marsh plants can sequestrate and inherently tolerate high metal concentrations found in salt marsh sediments. This work intended to understand the Halimione portulacoides (L.) Aellen strategies to prevent metal toxicity, by investigating the metal location in different plant organs and in the cell. A sequential extraction was performed on leaves, stems and roots of H. portulacoides in order to determine and compare the metal (Zn, Pb, Co, Cd, Ni and Cu) concentration in several fractions of the plant material (ethanolic, aqueous, proteic, pectic, polissacaridic, lenhinic and cellulosic). This study shows that all plant organs of H. portulacoides mostly retain metals in the cell wall (65% is the average for all studied metals stored in the root cell wall, 55% in the stems and 53% in the leaves), and the metal content in the intracellular compartment is much lower (21% in roots, 25% in stems and 32% in leaves). High levels of heavy metal in the sedimentary environment do not cause toxicity to H. portulacoides, because H. portulacoides immobilizes them in different cell compartments (cell wall+proteic fraction+intracellular) outside key metabolic sites.     

Assessing dam implementation impact on threatened carnivores: the case of Alqueva in SE Portugal

Large dam construction in water deficient areas is a management decision often controversial. Besides providing water storage, economical benefits, and a source of renewable energy, the construction and flooding caused by large dams cause disruptions in natural systems. We monitored the pre- and post-Alqueva dam impacts on the threatened carnivore species (polecat, otter, wildcat and Iberian lynx) populations in SE Portugal, and assessed which factors mostly contribute to post-dam distribution. Major short term impacts of large dams are: (1) increase in accessibility and human presence; (2) movement of heavy machinery and dam-workers; (3) deforestation with habitat loss and fragmentation; (4) change from lotic to lentic system; (5) lower prey availability and harsher capture; and (6) changes in land use adjacent to the reservoir. Thus, the response to those impacts can be predicted as a decline of polecat, wildcat and lynx distribution ranges, and a recovery of the otter from the severe short term impacts. Our results corroborate this hypothesis for all the species, especially during deforestation/early flooding. Otter's distribution range increased in the phase of greater impact, with a subsequent decrease with flooding. Our results suggest carnivores used "escape" areas with favourable habitat and prey conditions, however, the areas with higher probability of species presence decreased by two fold showing a drastic range reduction. To ensure populations' survival of these charismatic threatened carnivore populations of Mediterranean landscapes of south-east Portugal, we propose continuing the monitoring program and the development of a conservation program for the subsisting areas of optimal and suboptimal habitats.     

Characterization and validation of a Portuguese natural reference soil to be used as substrate for ecotoxicological purposes

This study describes the first attempt to validate a Portuguese natural soil (PTRS1) to be used as reference soil for ecotoxicological purposes, aimed to both: (i) obtain ecotoxicological data for the derivation of Soil Screening Values (SSVs) with regional relevance, acting as a substrate to be spiked with ranges of concentrations of the chemicals under evaluation and (ii) act as control and as substrate for the dilution of contaminated soils in ecotoxicological assays performed to evaluate the ecotoxicity of contaminated soils, in tier 2 of risk assessment frameworks, applied to contaminated lands. The PTRS1 is a cambisol from a granitic area integrated in the Central Iberian Zone. After chemical characterization of the soil in terms of pseudo-total metals, PAHs, PCBs and pesticide contents, it was possible to perceive that some metals (Ba, Be, Co, Cr and V) surpass the Dutch Target Values (Dtvs) corrected for the percentage of organic matter and clay of the PTRS1. Nevertheless, these metals displayed total concentrations below the background total concentrations described for Portuguese soils in general. The same was observed for aldrin, endosulfan I, endosulfan II, heptachlor epoxide, and heptachlor; however the Dtvs corrected become negligible. The performance of invertebrate and plant species, commonly used in standard ecotoxicological assays, was not compromised by both soil properties and soil metal contents. The results obtained suggest that the PTRS1 can be used as a natural reference soil in ecotoxicological assays carried out under the scope of ecological risk assessment.     

Geochemistry,mineralogy, solid-phase fractionation and oral bioaccessibility of lead in urban soils of Lisbon

An urban survey of Lisbon, the largest city in Portugal, was carried out to investigate its environmental burden, emphasizing metallic elements and their public health impacts. This paper examines the geochemistry of lead (Pb) and its influence on human health data. A total of 51 soil samples were collected from urban recreational areas used by children to play outdoors. The semi-quantitative analysis of Pb was carried out by inductively coupled plasma mass spectrometry after an acid digestion. X-ray diffraction was used to characterize the soil mineralogy. The solid-phase distribution of Pb in the urban soils was investigated on a subset of 7 soils, out of a total of 51 samples, using a non-specific sequential extraction method coupled with chemometric analysis. Oral bioaccessibility measurements were obtained using the Unified BARGE Method developed by the Bioaccessibility Research Group of Europe. The objectives of the study are as follows: (1) investigation of Pb solid-phase distribution; (2) interpretation of Pb oral bioaccessibility measurements; (3) integration of metal geochemistry with human health data; and (4) understanding the influence of geochemistry and mineralogy on oral bioaccessibility. The results show that the bioaccessible fraction of Pb is lower when major metal fractions are associated with less soluble soil phases such as Fe oxyhydroxides, and more increased when the metal is in the highly soluble carbonate phase. However, there is some evidence that the proportion of carbonates in the soil environment is also a key control over the oral bioaccessibility of Pb, irrespective of its solid-phase fractionation.     

Positive association between social and extra-pair mating in a polygynous songbird, the dickcissel (Spiza americana)

In polygynous species, males appear to gain additional offspring by pairing with multiple females simultaneously. However, this may not be true if some females copulate outside of the social pair bond. Polygynous males could experience lower paternity because of trade-offs among gaining multiple social mates, guarding fertility with these mates, and pursuing extra-pair matings. Alternatively, polygynous males could simultaneously gain extra social mates and have high paternity, either because of female preferences or because of male competitive attributes. We tested four predictions stemming from these hypotheses in a facultatively polygynous songbird, the dickcissel (Spiza americana). Unlike most previous studies, we found that males with higher social mating success (harem size) also tended to have higher within-pair paternity and that the number of extra-pair young a male sired increased significantly with his social mating success. Females that paired with mated males were not more likely to produce extra-pair young. In contrast, extra-pair paternity was significantly lower in the nests of females whose nesting activity overlapped that of another female on the same territory. This pattern of mating was robust to differences in breeding density. Indeed, breeding density had no effect on either extra-pair mating or on the association between polygyny and paternity. Finally, nest survival increased with harem size. This result, combined with the positive association between polygyny and paternity, contributed to significantly higher realized reproductive success by polygynous male dickcissels.     

Road traffic deaths in Brazil: rising trends in pedestrian and motorcycle occupant deaths

Objective: According to the World Health Organization, the global burden of road traffic mortality exceeds 1.27 million people annually; over 90 percent occur in low- and middle-income countries. Brazil's road traffic mortality rate of ～20 per 100,000 is significantly higher than nearby Chile or Argentina. To date, there has been very little information published on road traffic fatalities among vulnerable road users (VRUs) in Brazil. Methods: Road traffic fatality data from 2000 to 2008 were extracted from Brazil's Mortality Information System (SIM). Road traffic deaths were extracted using the International Classification of Diseases (ICD-10) V-codes (V01-V89) and then subcategorized by VRU categories. Information was then disaggregated by gender, age, and region. Results: In 2008, 39,211 deaths due to road traffic injuries were recorded in Brazil, resulting in a crude mortality rate of 20.7 per 100,000 inhabitants. Pedestrian mortality averaged 5.46 deaths per 100,000 between 2000 and 2008. The mortality rate for elderly pedestrians (80+ years) is 20.1 per 100,000, over 10 times that of 0- to 9-year-olds. In the past decade, motorcycle occupant mortality has dramatically increased by over 300 percent from 1.5 per 100,000 in 2000 to 4.7 per 100,000 in 2008. The 20- to 29-year age group remains most affected by motorcycle deaths, with a peak fatality rate of 10.76 per 100,000 in 2008. The north and northeast regions, with the lower per capita gross domestic product (GDP), have higher proportions of VRU deaths compared with other regions. Conclusions: Vulnerable road users are contributing an increasing proportion of the road traffic fatalities in Brazil. Nationally, elderly pedestrians are at particularly high risk and motorcycle fatalities are increasing at a rapid rate. Less prosperous regions have higher proportions of VRU deaths. Understanding the epidemiology of road traffic mortality in vulnerable road user categories will better allow for targeted interventions to reduce these preventable deaths.     

Widespread density-dependent seedling mortality promotes species coexistence in a highly diverse Amazonian rain forest

Negative density-dependent mortality can promote species coexistence through a spacing mechanism that prevents species from becoming too locally abundant. Negative density-dependent seedling mortality can be caused by interactions among seedlings or between seedlings and neighboring adults if the density of neighbors affects the strength of competition or facilitates the attack of natural enemies. We investigated the effects of seedling and adult neighborhoods on the survival of newly recruited seedlings for multiple cohorts of known age from 163 species in Yasuni National Park, Ecuador, an ever-wet, hyper-diverse lowland Amazonian rain forest. At local scales, we found a strong negative impact on first-year survival of conspecific seedling densities and adult abundance in multiple neighborhood sizes and a beneficial effect of a local tree neighborhood that is distantly related to the focal seedling. Once seedlings have survived their first year, they also benefit from a more phylogenetically dispersed seedling neighborhood. Across species, we did not find evidence that rare species have an advantage relative to more common species, or a community compensatory trend. These results suggest that the local biotic neighborhood is a strong influence on early seedling survival for species that range widely in their abundance and life history. These patterns in seedling survival demonstrate the role of density-dependent seedling dynamics in promoting and maintaining diversity in understory seedling assemblages. The assemblage-wide impacts of species abundance distributions may multiply with repeated cycles of recruitment and density-dependent seedling mortality and impact forest diversity or the abundance of individual species over longer time scales.     

LES validation of lock-exchange density currents interacting with an emergent bluff obstacle

Environmental Fluid Mechanics - We address the capability of large eddy simulation (LES) to predict the physics of density currents interacting with bluff obstacles. Most density currents of...     

Global variability of food waste chemical composition and its consequences on the production of biofuels and chemical compounds

Journal of Material Cycles and Waste Management - The use of food waste (FW) for the production of biofuels and value-added compounds is growing worldwide. However, the significant chemical...