Comparing the Number of Ozone Exceedances in Different Seasons of the Year in Mexico City

Ozone air pollution is a serious problem in several cities of the world. Hence, to analyse the behaviour of this pollutant is a very important issue. One problem of interest is to study the behaviour of the inter-occurrences times between two ozone exceedances, i.e. between two days in which the pollutant’s measurement surpasses a given threshold. Another interest resides in comparing the behaviour of ozone measurements in different seasons of the year. In this paper we use some Poisson models to analyse this problem. The time interval at which the ozone measurements were taken is split into subintervals corresponding roughly to the seasons of the year. We consider three parametric forms for the mean of the Poisson model, and consequently for the mean of the inter-occurrences times. In each model, the parameters describing its mean are estimated using Bayesian inference via Markov chain Monte Carlo methods. The models are applied to the ozone measurements provided by the Mexico City monitoring network. Theoretical results suggest that an increase has occurred in the mean inter-exceedances times and this is corroborated by the observed data. Differences between the behaviour of the pollutant during different seasons of the year are also detected as well as similarities in the same season in different years. Besides estimating the mean of the Poisson models, inference for the possible presence and location of change-points indicating change of parameters of the model is also performed.     

Chemical and toxicological evaluation along with unprecedented transformation products during photolysis and heterogeneous photocatalysis of chloramphenicol in different aqueous matrices

Environmental Science and Pollution Research - As the presence of antibiotics in environmental waters enhances antimicrobial resistance, photolysis and heterogeneous photocatalysis of...     

Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.     

The implementation of environmental education to promote sustainability: an overview of the processes and challenges

ABSTRACT

This paper interprets aspects of the implementation of environmental education in a Higher Education Institution, situated in a developing country, to promote Education for Sustainable Development (ESD). The paper will allow educators to categorise the multiplicity of ESD programmes and projects in higher education institutions, determine their limitations and acceptability, and benefit from the theoretical framework of affective learning in designing new ESD interventions. The paper will also provide an overview of the processes required to establish ESD in developing and developed countries. This paper will further help universities to develop a better understanding of how integration of the three components of sustainable development – economic development, social development and environmental protection – can be incorporated in higher education. The paper explores the challenges for planning the implementation of ESD in an education faculty, outlining the potential lessons learned that could assist in improving ESD efforts in Faculties of Education.     

Control of molecular weight distribution of the biopolymer pullulan produced byAureobasidium pullulans

The influence of carbon, nitrogen, and phosphate source, along with concentration, was determined for effect on the weight average molecular weight, molecular weight distribution, and yield of pullulan produced byAureobasidium pullulans NRRL-Y 6220. Batch systems, scale-up batch, and continuous fermentations of 1 L and 10 L were also evaluated as were processing variables, including solvents, and extraction conditions. Products with weight average molecular weight from 1.0 × 10⁵ to 4.0 × 10⁶ were produced in 100-g quantities by varying fermentation conditions such as constituents of the culture medium, pH, and length of incubation. Three sets of culture conditions were defined for the formation of low (<5.0×10⁵), medium (1.0–2.0×10⁶), and high (>2.0×10⁶) weight average molecular weight polymer. These defined molecular weight fractions of pullulan were used in further studies in producing films and fibers.     

Yeasts as a model for assessing the toxicity of the fungicides Penconazol, Cymoxanil and Dichlofluanid

In the present work the sensitivity of yeast strains of Kluyveromyces marxianus, Pichia anomala, Candida utilis, Schizosaccharomyces pombe and Saccharomyces cerevisiae, to the fungicides cymoxanil, penconazol, and dichlofluanid, was evaluated. Dichlofluanid induced the most negative effects, whereas penconazol in general was not very toxic. Overall, our results show that the parameters IC50 for specific respiration rates of C. utilis and S. cerevisiae and C(D) for cell viability of S. cerevisiae can be applied to quantify the toxicity level of the above compounds in yeast. Hence, could be explored as an alternative or at least as a complementary test in toxicity studies and, therefore, its potential for inclusion in a tier testing toxicity test battery merits further research.     

Mill leaching: a viable substitute for mercury amalgamation in the artisanal gold mining sector?

Artisanal small-scale gold miners (ASM) occasionally employ whole ore amalgamation by adding mercury into ball mills to recover gold. In this process, 25–30% of the mercury added is lost to the environment. It is also inefficient less than 30% of gold is recovered. Amalgamation, followed by cyanidation, has been observed at many artisanal mining sites. This combination poses additional environmental and health consequences. Tests with ore samples from Talawaan, North Sulawesi, Indonesia indicate the possibility of replacing mercury by cyanidation in the ball mill, reaching gold extraction of 93% in 6 h of leaching. The gold in the Indonesian ore sample is fine and less than 8% of gold recovery was obtained with gravity concentration of the ore ground 80% below 0.25 mm, which is a reasonably fine grain size for artisanal gold operations. Replacing mercury addition with cyanidation in ball mills was implemented in one artisanal gold mining operation in Portovelo, Ecuador, achieving 95% of gold extraction in 8 h of mill leaching. This technique demonstrated a drastic improvement in gold recovery. It was found to be a simple, inexpensive technique well accepted by local miners. The results from laboratory and field tests are promising; however a thorough investigation into the socio-economic and environmental aspects of this presented alternative must be conducted prior to introduction.     

An ultrastructural study of Crassostrea angulata (Mollusca,Bivalvia) spermatogenesis

The cytoplasm of Crassostrea angulata (collected from the Atlantic coast of Northern Spain, Galiza, between 1992 and 1993) spermatogonia contains a few proacrosomal dense vesicles and intermitochondrial round granulo-fibrillar dense bodies. In primary spermatocytes, large cytoplasmic spaces appear occupied by large round and more scattered granulo-fibrillar dense bodies which are intermingled with cord-like dense structures and are in close association with mitochondria and the rough endoplasmic reticulum. As a result of Golgian activity, the number of dense proacrosomal vesicles increases and a flagellum arises from the centrioles. During the second meiotic division, several round dense bodies surrounding cord-like dense structures as well as dense proacrosomal vesicles, were observed between chromosomes. During spermiogenesis, no Golgian activity was noticed, and only the rough endoplasmic reticulum was observed in close association with proacrosomal vesicles. Similar results were observed for Ostrea edulis (collected from the Atlantic coast of southern Portugal, Algarve, between 1992 and 1993). Spermatozoa of both species are of the aquasperm type, and although their ultrastructure is quite similar, silver and phosphotungstic acid-chromic acid stainings enabled us to clearly distinguish both species at the ultrastructural level. The different morphological aspects of spermatogenesis in the Pteriomorphia and the use of silver and PTA stainings in the Mollusca are reviewed and discussed.     

Spirometric tests to assess the prevalence of childhood asthma at Portuguese rural areas: influence of exposure to high ozone levels

The study here reported aimed to: i) evaluate the prevalence of childhood asthma at a Portuguese rural area with high ozone concentrations through lung function tests, validating the previously estimated one assessed through questionnaires (similar to those of the ISAAC); ii) compare the achieved prevalence with the one reported at an unexposed area (with low ozone concentrations), aiming to evaluate the influence of exposure to high ozone levels; and iii) determine potential risk factors. Ninety-five of the original 478 children that completed the questionnaires, mentioned to have at least one of asthma symptoms (wheeze, dyspnea or cough) and were therefore evaluated by spirometry. FEV(1) was in average 89.7% for asthmatics and 102.8% for non-asthmatics. For the studied sample the risk was higher for girls with a tendency to be higher from 8 to 10 years old. Lifetime prevalence of childhood asthma at the exposed area was 9.2%. Children living at the exposed area had 3 times higher risk of having asthma than those living at the unexposed area. Considering that ozone concentrations were the main difference between both areas, it can be suggested that ozone pollution increased asthma prevalence. Nevertheless, it should be remarked that further studies should be done to confirm these results.     

Rural fences in agricultural landscapes and their conservation role in an area of caatinga (dryland vegetation) in Northeast Brazil

Fences are very common in rural areas, and represent important landscape elements in both tropical and temperate climate regions. In spite of their marked presence and importance, fences have been little studied, principally in Brazil. The present study examined the types of fences, the diversity of species used in their construction, as well as the diversity of their uses in a rural community in the municipality of Caruaru, Pernambuco State, northeastern Brazil. Fifty meters of fence-line in each of 50 rural properties in the community were examined, noting the diameter, height and identity of all vegetation elements used in their composition. Semi-structured interviews were also held with their builders in order to obtain information concerning fence uses. In the total of 2,500 linear meters of fence-line, 4,953 individual plant elements were identified, belonging to 51 different species. A majority of the fence elements were non-living fence posts, although the number of living posts was high. Of the total number of fence elements, 66.7% were native to the caatinga region. The large number of native species used as non-living fence posts indicates an intensive use of the caatinga vegetation and suggests the need to stimulate the use of living fence posts for conservation purposes.