Radon in indoor air of primary schools: determinant factors,their variability and effective dose

Radon is a radioactive gas, abundant in granitic areas, such as in the city of Porto at the north-east of Portugal. This gas is a recognized carcinogenic agent, being appointed by the World Health Organization as the leading cause of lung cancer after smoking. The aim of this preliminary survey was to determine indoor radon concentrations in public primary schools, to analyse the main factors influencing their indoor concentration levels and to estimate the effective dose in students and teachers in primary schools. Radon concentrations were measured in 45 classrooms from 13 public primary schools located in Porto, using CR-39 passive radon detectors for about 2-month period. In all schools, radon concentrations ranged from 56 to 889 Bq/m³ (mean = 197 Bq/m³). The results showed that the limit of 100 Bq/m³ established by WHO IAQ guidelines was exceeded in 92 % of the measurements, as well as 8 % of the measurements exceeded the limit of 400 Bq/m³ established by the national legislation. Moreover, the mean annual effective dose was calculated as 1.25 mSv/y (ranging between 0.58 and 3.07 mSv/y), which is below the action level (3–10 mSv). The considerable variability of radon concentration observed between and within floors indicates a need to monitor concentrations in several rooms for each floor. A single radon detector for each room can be used, provided that the measurement error is considerably lower than variability of radon concentration between rooms. The results of the present survey will provide useful baseline data for adopting safety measures and dealing effectively with radiation emergencies. In particular, radon remediation techniques should be used in buildings located in the highest radon risk areas of Portugal. The results obtained in the current study concerning radon levels and their variations will be useful to optimize the design of future research surveys.     

Elucidating the function of ejaculate expulsion and consumption after copulation by female Euxesta bilimeki

Postcopulatory processes can influence male reproductive success in several animal species. Females can use different mechanisms to bias male paternity after copulation. One of such mechanisms consists in expelling all or part of the ejaculate after copulation. Euxesta bilimeki is an Ulidiid fly whose females not only frequently expel ejaculates after mating but also consume the ejaculate after expulsion. In order to understand the significance of these behaviors we examined video recordings of courtship, copulatory, and postcopulatory behaviours. The presence of sperm in female storage organs was confirmed after mating with males of different sizes and was correlated with duration of courtship, copulation, and the period from the end of copulation to ejaculate expulsion. The effect of ejaculate consumption on female fitness (fecundity and longevity) was compared among females held under different dietary treatments: a rich diet consisting of protein, sugar and water, an intermediate diet composed of sugar and water, a poor diet of only water and females that were completely deprived of food and water. All of the observed females expelled ejaculates after mating. The probability of storing sperm in the two spermathecae and the ventral receptacle was correlated with interactions between the duration of all behaviours examined and male size. Except for starved females, who lived longer when allowed to consume ejaculates, ejaculate consumption had no effect on fitness. Results suggest that females can bias sperm storage according to male mating effort, while the consumed ejaculate had some nutritional value only evident when females were completely starved.     

Children of divorce: effects of adult replacements on previous offspring in Argentinean owl monkeys

According to the Evolutionary Theory of the Family, the replacement of one pair-member by an intruder may have profound consequences for the existing offspring. Step-parents are expected to provide less care towards unrelated immatures than to genetic offspring, unless caring also serves as a mating strategy. Furthermore, because an intruder will be a potential mate for opposite-sexed offspring, relationships between offspring and same-sex parents are predicted to deteriorate. To test these predictions, we studied an Azara’s owl monkey (Aotus azarai) population in Argentina exhibiting serial monogamy and bi-parental care. Since 1997, we have collected demographic data from ca. 25 groups and inter-individual distance data from ca. 150 marked individuals. First, we compared survival and dispersal age of immatures in groups with and without replacements to investigate whether parental care serves as a mating strategy. Second, we compared sex-specific age at dispersal for groups with replacement of opposite-sex parents, same-sex parents, or in stable groups in order to test whether relationships between offspring and same-sex parents deteriorated after the replacement of the other parent. Survival and dispersal ages were not negatively associated with replacements, suggesting that male care might serve, at least partly, as a mating strategy. The time lag between a replacement and the subsequent dispersal of female offspring was greater if the intruder was a male, while the offspring and same-sex parents were less often nearest neighbors after replacements than before. Our results suggest that family disruption through the replacement of a parent is not associated with decreased offspring survival or early dispersion of juveniles, but deteriorates parent–offspring relationships.     

Bayesian nonparametric inference for the overlap of daily animal activity patterns

The study of the interaction among species is an active area of research in Ecology. In particular, it is of interest to evaluate the overlap of their ecological niches. Temporal activity is one of the niche’s axes most commonly used to explore ecological segregation among animal species, and many contributions focus on the overlap of this variable. Once the information of the temporal activity is obtained in the wild, the data is treated as a random sample. There exist different methods to estimate the overlap. Specifically, in the case of two species, one possibility is to estimate the density of the temporal activity of each species and then evaluate the overlap between these density functions. This leads naturally to the analysis of circular data. Most of the procedures currently in use impose some rather restrictive assumptions on the probabilistic models used to describe the phenomena, and only provide approximate measures of the uncertainty involved in the process. In this article, we propose a Bayesian nonparametric approach which incorporates a well-defined noninformative prior. We take advantage of the data structure to define such a prior in terms of the predictive distribution. To the best of our knowledge, this is a novel approach. Our procedure is compared with a well-known method using simulated data, and applied to the analysis of real camera-trap data concerning two mammalian species from the El Triunfo biosphere reserve (Chiapas, Mexico).     

A lover, not a fighter: mating causes male crickets to lose fights

Both resource-holding potential (RHP) and experience in aggressive contests are known to affect future aggressive behaviour. However, few studies have examined the effects of mating experience on agonistic behaviour, despite the fact that dominant males usually acquire more matings. We investigated the effect of mating experience on male aggressive behaviour including the relationship between RHP and fighting success in the fall field cricket, Gryllus pennsylvanicus. We formed pairs of size- and age-matched males that varied in RHP (relative weapon size) and conducted two experiments. In the first, we varied male mating experience by allowing one male in a pair to either be (a) ‘mated’: court, be mounted and copulate with a virgin female or (b) ‘experienced’: court, be mounted, but prevented from copulating. The second experiment varied postcopulatory experience where the male was allowed (‘contact’) or prevented from (‘no-contact’) continued contact with his recent mate. Following treatment, experimental males engaged in an aggressive contest with the naïve size- and age-matched male. In our first experiment, we found that mated and experienced males were equally likely to escalate contests to combat with a naïve opponent, but mated males were less likely than experienced males to win. There was no effect of mating on the relationship between RHP and fighting success. In our second experiment, we found no effect of maintaining contact with the female on the tendency to escalate or the probability of winning. As in the first experiment, males with relatively larger heads again won more fights and this relationship was unaffected by male experience. These results suggest that mating is itself detrimental to male success in aggressive contests, but that this effect is not sufficient to eliminate the effect of RHP on fighting success.     

Evaluation of metabisulfite and a commercial steel wool for removing chromium(VI) from wastewater

Efficiency of metabisulfite and a commercial steel wool as reducing agents in the removal of Cr(VI) from wastewaters was evaluated. Chromium(VI) was converted to Cr(III), precipitated with NaOH, and removed by filtration. A reduction of more than 1.0 × 10⁵ and 4.0 × 10⁵ fold in total Cr and the Cr(VI) concentrations, respectively, was observed by employing steel wool masses as low as 0.4420 g to 30-mL solutions of wastewater. Chromium(III) hydroxide obtained after the treatment was recycled and used as marker in cattle nutrition studies. The liquid residue obtained after the treatment was reused as precipitation agent replacing NaOH.     

Marine Protected Dramas: The Flaws of the Brazilian National System of Marine Protected Areas

This article discusses the current problems and issues associated with the implementation of a National System of Marine Protected Areas in Brazil. MPA managers and higher governmental level authorities were interviewed about their perceptions of the implementation of a national MPA strategy and the recent changes in the institutional arrangement of government marine conservation agencies. Interviewees’ narratives were generally pessimistic and the National System was perceived as weak, with few recognizable marine conservation outcomes on the ground. The following major flaws were identified: poor inter-institutional coordination of coastal and ocean governance; institutional crisis faced by the national government marine conservation agency; poor management within individual MPAs; problems with regional networks of marine protected areas; an overly bureaucratic management and administrative system; financial shortages creating structural problems and a disconnect between MPA policy and its delivery. Furthermore, a lack of professional motivation and a pessimistic atmosphere was encountered during many interviews, a malaise which we believe affects how the entire system is able to respond to crises. Our findings highlight the need for a better understanding of the role of ‘leadership’ in the performance of socio-ecological systems (such as MPA networks), more effective official evaluation mechanisms, more localized audits of (and reforms if necessary to) Brazil’s federal biodiversity conservation agency (ICMBio), and the need for political measures to promote state leadership and support. Continuing to focus on the designation of more MPAs whilst not fully addressing these issues will achieve little beyond fulfilling, on paper, Brazil’s international marine biodiversity commitments.     

Using Mediterranean shrubs for the phytoremediation of a soil impacted by pyritic wastes in Southern Spain: a field experiment

Re-vegetation is the main aim of ecological restoration projects, and in Mediterranean environments native plants are desirable to achieve successful restoration. In 1998, the burst of a tailings dam flooded the Guadiamar river valley downstream from Aznalcóllar (Southern Spain) with sludges that contained elevated concentrations of metals and metalloids, polluting soils and waters. A phytoremediation experiment to assess the potential use of native shrub species for the restoration of soils affected by the spillage was performed from 2005 to 2007, with soils divided into two groups: pH < 5 and pH > 5. Four native shrubs (Myrtus communis, Retama sphaerocarpa, Rosmarinus officinalis and Tamarix gallica) were planted and left to grow without intervention. Trace element concentrations in soils and plants, their extractability in soils, transfer factors and plant survival were used to identify the most-interesting species for phytoremediation. Total As was higher in soils with pH < 5. Ammonium sulphate-extractable zinc, copper, cadmium and aluminium concentrations were higher in very-acid soils, but arsenic was extracted more efficiently when soil pH was >5. Unlike As, which was either fixed by Fe oxides or retained as sulphide, the extractable metals showed significant relationships with the corresponding total soil metal concentration and inverse relationships with soil pH. T. gallica, R. officinalis and R. sphaerocarpa survived better in soils with pH > 5, while M. communis had better survival at pH < 5. R. sphaerocarpa showed the highest survival (30%) in all soils. Trace element transfer from soil to harvestable parts was low for all species and elements, and some species may have been able to decrease trace element availability in the soil. Our results suggest that R. sphaerocarpa is an adequate plant species for phytostabilising these soils, although more research is needed to address the self-sustainability of this remediation technique and the associated environmental changes.     

Okadaic acid induces morphological changes, apoptosis and cell cycle alterations in different human cell types

Okadaic acid (OA) is a marine toxin produced by dinoflagellate species which is frequently accumulated in molluscs usual in the human diet. The exact action mechanism of OA has not been described yet and the results of most reported studies are often conflicting. The aim of this work was to evaluate the OA effects on morphology, cell cycle and apoptosis induction by means of light microscopy and flow cytometry, in three different types of human cells (leukocytes, HepG2 cells and SHSY5Y cells). Cells were treated with a range of OA concentrations in the presence and absence of S9 fraction. OA induced morphological changes in all the cell types studied, and cell cycle disruption only in leukocytes and neuronal cells. SHSY5Y cells were the most sensitive to OA assault. Results obtained in the presence and absence of metabolic activation were similar, suggesting that OA acts both directly and indirectly. Furthermore, OA was found to increase the subG(1) region in the flow cytometry cell cycle analysis, suggesting induction of apoptosis. These results were confirmed by the employment of specific methodologies for studying apoptosis such as caspase 3 activation and annexin V staining. Increases in the apoptosis rate were obtained in all the cells treated in the absence of S9 fraction, accompanied by increases in caspase 3 activation, suggesting that apoptosis induced by OA is a caspase 3-dependent process. Nevertheless, in the presence of S9 fraction no apoptosis was detected, indicating a metabolic detoxifying activity, although necrosis was observed in neuroblastoma cells.