Dominance and the dynamics of phenotype-limited distribution in common cranes

We studied the behavior of 13 radiotagged cranes dispersing from a communal roost over days when they changed their main daily foraging area between consecutive days during two winter seasons. Individuals went to a new foraging zone when on the previous day their morning food intake had fallen below their mean morning food intake measured over the whole winter. Food intake on the day before a change in foraging area was positively correlated with dominance rank. Dominant cranes changed to new zones with higher numbers of birds and food density, while subordinate cranes went to new zones with lower numbers of birds. As a result, all birds increased their food intake over that of the previous day. Dominant cranes remained more faithful to their most preferred foraging zone, where they spent 69% of the mornings, while subordinate birds were more mobile, switching among zones frequently. Dominant birds left the roost later than subordinate birds on the days they changed to a new zone, which could be used to track the main departing flows. The results suggest that the dynamics that led to a truncated phenotype-limited distribution were determined by social dominance and food abundance, with dominant cranes shifting to a new zone to maintain their high intake levels and subordinates changing more frequently whenever their daily intake did not reach the minimum metabolic requirements. Received: 16 December 1996 / Accepted after revision: 22 February 1997     

Preliminary assessment of plastic waste valorization via sequential pyrolysis and catalytic reforming

In this article, a life cycle assessment approach is used to carry out a preliminary assessment of the environmental and energy performance of a specific chemical recycling and recovery system that supplies a variety of petrochemical blendstocks through the sequential pyrolysis and catalytic reforming of plastic wastes. Characterization results are presented for a selection of seven impact categories: abiotic depletion, global warming, acidification, eutrophication, ozone layer depletion, photochemical oxidant formation and cumulative non-renewable energy demand. From a combined environmental and energy perspective, the results suggest the suitability of this system for plastic waste valorization. However, improvement actions aimed at reducing the thermal energy demand and mitigating direct emissions to the air should be undertaken. Furthermore, the environmental profiles of the proposed petrochemical blendstocks are compared with those of conventional energy products. A comparison among this chemical recycling and recovery system and two conventional management practices (municipal incineration and landfilling) is also addressed. The results show that the considered system could entail relevant environmental and energy benefits when compared to conventional energy systems and waste management strategies.     

Effectiveness of protected areas in the Colombian Andes: deforestation, fire and land-use changes

Protected areas (PAs) are one of the most common conservation strategies to halt biodiversity loss. However, little is known about their current effectiveness and how they could behave under projected scenarios of change, especially in the mountain ecosystems of the Andean region. In this study, we assess the role of protected areas against deforestation and fire incidence in the Colombian Andes and how variables associated with biophysical and context drivers such as the size, year of creation and geographic location of the PAs affect their effectiveness. For the long-term, we have addressed the question of how effective these areas will be under three different scenarios of change for the period between 2020 and 2050, including a reference scenario and two scenarios of increasing pastureland and croplands. The results obtained indicated that both deforestation and fire levels were significantly lower inside protected areas than outside their borders. Concerning variables affecting deforestation and fire, only the type of ecosystem affected these processes in this study. The magnitude of forest loss was different between the analysed scenarios and depended on the location of the PAs. The PAs located in the Western Mountain Range presented the largest values of deforestation but the lowest number of fire incidences. This finding could be related to the presence of processes other than fire, such as illegal logging or selective extraction. The largest losses are expected in the PAs associated with the Eastern and Central mountain ranges, whereas the Western Mountain range will have the lowest loss. We conclude that although the Andes Mountains are a highly transformed and dynamic region, the current PAs have been effective barriers for deforestation and fire. However, the creation of new areas and the maintenance of the current PAs should take into account the interaction with the surrounding population, especially in those areas that are more sensitive to change.     

Chelate-induced phytoextraction of metal polluted soils with Brachiaria decumbens

Chelate-induced phytoextraction with high biomass plant species has been proposed for the clean-up of heavy metal polluted soils. In the current work, the effect of the application of two different chelating agents, i.e. EDTA and EDDS, on the metal phytoextraction capacity of Brachiaria decumbens was studied. Although EDTA was, in general, more effective in soil metal solubilization, EDDS, a chelate less harmful to the environment, was more efficient inducing metal accumulation in B. decumbens shoots than EDTA. Indeed, in a moderately heavy metal polluted soil, EDDS caused a 2.54, 2.74 and 4.30-fold increase in Cd, Zn, and Pb shoot metal concentration, respectively, as compared to control plants. In this same soil, EDTA caused a 1.77, 1.11 and 1.87-fold increase in Cd, Zn, and Pb shoot metal concentration, respectively, as compared to control plants. EDDS was also more effective than EDTA in stimulating the translocation of metals from roots to shoots. B. decumbens plants were able to grow in the metal polluted soils showing no visible symptoms of phytotoxicity, which suggests their metal tolerance. Finally, B. decumbens, a fast-growing, high biomass, aluminum tolerant plant species, that has a well-established agronomic system, fulfills most of the requirements for chemically-induced phytoextraction.     

Analysing the incorporation of sustainability themes into the university curricula: a case study of a Spanish public university

From an international view, several papers have analysed how sustainability themes are integrated into the university curricula. In Spain, few studies to date have examined the extent to which universities are incorporating sustainability themes into their curricula. In view of such considerations, this article examines the extent to which sustainability themes are being incorporated into the curricula of a Spanish public university strongly committed to signing sustainability policies and declarations. In addition, this study analyses the main barriers to the incorporation of sustainability themes into the curricula of this university. To accomplish this task, this article uses different methodological instruments over three phases through a case study approach. The findings of this study suggest how the university examined has many difficulties in incorporating, holistically or separately, sustainability themes in its formal courses despite having so many policies, regulations and a commitment to sustainability.     

Non-invasive measurement of the physiological stress response of wild rabbits to the odour of a predator

Summary. Stress has been widely studied in different mammals, but the physiological stress reaction that the odour of a predator could induce in preys has not received much attention. Besides, not all the animals would respond to the same extent to a known stressor. We developed an experimental procedure with eleven na?ve European rabbits (Oryctolagus cuniculus) in order to determine the individual physiological response to the olfactory detection of a potential predator. The rabbits were housed singly in small enclosures with a concrete burrow system and food and water were available ad libitum. The animals followed a control trial, without odour, and an experimental trial where we confronted the rabbits with fox (Vulpes vulpes) odour. Furthermore, another sample of eleven rabbits followed a control procedure subjected to the same housing and handling procedures but without facing the predator odour. In order to assess the physiological response we analysed the concentration of glucocorticoid metabolites in the faeces of the rabbits. Therefore, everyday faecal samples were collected and analysed with an enzyme immunoassay in order to measure the corticosterone metabolites (CM), particularly, those metabolites with a 5α-3β, 11β-diol structure. After validating the assay for wild rabbits, we found that the simulated presence of a predator (fox odour) in the enclosure resulted in an increase in faecal CM concentrations. However, the stressor did not affect all the animals in the same way. We found a general increase in the individual differences. In particular, males experienced a higher increase than females, though the overall response was similar for both sexes. To our knowledge this is one of the first attempts to analyse the assessment of the risk of predation by means of non-invasive methods.     

An air quality modeling study comparing two possible sites for the new international airport for Mexico City

Using an air quality model, two future urban scenarios induced by the construction of the new international airport for Mexico City are compared at a regional level. The air quality model couples the meteorology model MM5 and state-of-the-art photochemistry. The air quality comparison is made using metrics for the criterion gases selected for the study. From the two urban scenarios compared, the option for Tizayuca is moderately better than the option for Texcoco, because relative reductions in O3 and other photochemical pollutants are achieved over highly populated areas. Regardless of the site, the air quality for the central region of Mexico in the future will deteriorate. In the region of central Mexico, SO2 and NO2 will become important pollutants.     

Performance of a submerged membrane bioreactor system for biological nutrient removal.

A pilot submerged membrane bioreactor coupled with biological nutrient removal was used to treat the primary effluent at a municipal wastewater treatment plant. Long-term experiments were conducted by varying hydraulic retention time from 6 to 8 hours and solids retention time from 20 to 50 days, respectively. The performance was assessed by monitoring key wastewater parameters, including chemical oxygen demand (COD), nitrogen, and phosphorus concentration in individual anoxic, anaerobic, aerobic, and membrane separation zones. Results showed that the tested system can consistently achieve COD, nitrogen, and phosphorus removal efficiencies at 80 to 98%, 70 to 93%, and 89 to 98%, respectively. Effluent COD remained low as a result of efficient solid retention, even though there was great variation in influent quality. However, total nitrogen increased proportionally with influent concentration. At a 50-day solids retention time, higher COD and nitrogen oxides specific utilization rates in the anoxic zone resulted in a high production of nitrogen oxides in the subsequent aerobic zone.     

Wet peroxide degradation of atrazine

The high temperature (150-200 degrees C), high pressure (3.0-6.0 MPa) degradation of atrazine in aqueous solution has been studied. Under these extreme conditions atrazine steadily hydrolyses in the absence of oxidising agents. Additionally, oxygen partial pressure has been shown not to affect atrazine degradation rates. In no case mineralisation of the parent compound was observed. The addition of the free radical generator hydrogen peroxide to the reaction media significantly enhanced the depletion rate of atrazine. Moreover, partial mineralisation of the organics was observed when hydrogen peroxide was used. Again, oxygen presence did not influence the efficiency of the promoted reaction. Consecutive injections of hydrogen peroxide throughout the reaction period brought the total carbon content conversion to a maximum of 65-70% after 40 min of treatment (suggesting the total conversion of atrazine to cyanuric acid). Toxicity of the effluent measured in a luminometer decreased from 93% up to 23% of inhibition percentage. The process has been simulated by means of a semi-empirical model.