Modelling annual pasture dynamics: Application to stomatal ozone deposition

Modelling ozone (O₃) deposition for impact risk assessment is still poorly developed for herbaceous vegetation, particularly for Mediterranean annual pastures. High inter-annual climatic variability in the Mediterranean area makes it difficult to develop models characterizing gas exchange behaviour and air pollutant absorption suitable for risk assessment. This paper presents a new model to estimate stomatal conductance (g_s) of Trifolium subterraneum, a characteristic species of dehesa pastures. The MEDPAS (MEDiterranean PAStures) model couples 3 modules estimating soil water content (SWC), vegetation growth and g_s. The g_s module is a reparameterized version of the stomatal component of the EMEP DO₃SE O₃ deposition model. The MEDPAS model was applied to two contrasting years representing typical dry and humid springs respectively and with different O₃ exposures. The MEDPAS model reproduced realistically the g_s seasonal and inter-annual variations observed in the field. SWC was identified as the major driver of differences across years. Despite the higher O₃ exposure in the dry year, meteorological conditions favoured 2.1 times higher g_s and 56 day longer growing season in the humid year compared to the dry year. This resulted in higher ozone fluxes absorbed by T. subterraneum in the humid year. High inter-family variability was found in gas exchange rates, therefore limiting the relevance of single species O₃ deposition flux modelling for dehesa pastures. Stomatal conductance dynamics at the canopy level need to be considered for more accurate O₃ flux modelling for present and future climate scenarios in the Mediterranean area.     

Shifts in grassland invasibility: effects of soil resources, disturbance, composition, and invader size

There is an emerging recognition that invasibility is not an intrinsic community trait, but is a condition that fluctuates from interactions between environmental forces and residential characters. Elucidating the spatiotemporal complexities of invasion requires inclusion of multiple, ecologically variable factors within communities of differing structure. Water and nutrient amendments, disturbance, and local composition affect grassland invasibility but no study has simultaneously integrated these, despite evidence that they frequently interact. Using a split-plot factorial design, we tested the effects of these factors on the invasibility of C3 pasture communities by smooth pigweed Amaranthus hybridus L., a problematic C4 forb. We sowed seeds and transplanted 3-week old seedlings of A. hybridus into plots containing monocultures and mixtures of varying composition, subjected plots to water, soil disturbance, and synthetic bovine urine (SBU) treatments, and measured A. hybridus emergence, recruitment, and growth rate. Following SBU addition, transplanted seedling growth increased in all plots but differed among legume and nonlegume monocultures and mixtures of these plant types. However, SBU decreased the number and recruitment rate of emerged seedlings because high residential growth reduced light availability. Nutrient pulses can therefore have strong but opposing effects on invasibility, depending on when they coincide with particular life history stages of an invader. Indeed, in SBU-treated plots, small differences in height of transplanted seedlings early on produced large differences in their final biomass. All facilitative effects of small-scale disturbance on invasion success diminished when productivity-promoting factors were present, suggesting that disturbance patch size is important. Precipitation-induced invasion resistance of C3 pastures by a C4 invader was partly supported. In grazed grasslands, these biotic and environmental factors vary across scales and interact in complex ways to affect invasibility, thus a dynamic patch mosaic of differential invasion resistance likely occurs in single fields. We propose that disturbance patch size, grazing intensity, soil resource availability, and resident composition are inextricably linked to grassland invasions and comment on the utility of community attributes as reliable predictors of invasibility. Lastly, we suggest temporal as well as spatial coincidences of multiple invasion facilitators dictate the window of opportunity for invasion.     

Double genetically modified symbiotic system for improved Cu phytostabilization in legume roots

Environmental Science and Pollution Research - Excess copper (Cu) in soils has deleterious effects on plant growth and can pose a risk to human health. In the last decade, legume-rhizobium...     

Recycling extruded polystyrene by dissolution with suitable solvents

The amount of extruded polystyrene (XPS) waste has increased in recent years due to the increase of its use in the thermal insulation of buildings, transport vehicles, and refrigerators, among others. Dissolution with suitable solvents to achieve a volume reduction of more than 100 times without degradation of polymer chains is one of the cheapest and most efficient methods of recycling XPS. Several environmentally friendly solvents have been tested as dissolution agents for XPS volume reduction; the action of these solvents does not produce any degradation of polymer chains. The solubility of the polymer in such solvents at different temperatures was investigated. The solvent can be easily recycled by distillation, obtaining a high-quality recycled polymer. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

Pilot study on the influence of stress caused by the need to combine work and family on occupational accidents in working women

The influx of a large number of women into the workforce involves the need for these women to combine family and work responsibilities. Multiple roles lead to work–family conflict. This study analyzes the influence of work–family conflict on the causes of minor occupational accidents suffered by working women. A survey was done on working women in the Madrid region, who had suffered a minor occupational accident in 2004. The main finding was that nearly half of the women with children considered that the stress and fatigue caused by trying to combine work and family played a part in the accident; 21% of the respondents whose accidents took place while traveling to or from work and 11% the respondents who suffered the accident in the workplace said that family reasons played a part. Additionally, 50% of the women suffered after-effects as a result of the accident; children had to change their routine in almost 1 in 4 cases; nearly a quarter of the respondents said their work situation had been temporarily modified. This point to a need for polices that encourage men and employers to contribute more to solve work–family conflicts.     

Preparation and characterization of ceramic products by thermal treatment of sewage sludge ashes mixed with different additives

The study of the ceramic characteristics of sludge ashes, alone or mixed with additives (kaolin, montmorillonite, illitic clay, powdered flat glass) includes characterization of additives, preparation of probes (dry or wet mixed), thermal treatment (up to 1200 degrees C, except melting or deformation) and control (densities, compressive strengths and water absorption). Thermal treatment increases the density and compressive strength of probes (both parameters go through maxima, with later decreases) and decreases the absorption of water. The densification is also revealed by the evolution of the ratio of decrease of volume/loss of mass. The maximum values of compressive strengths were obtained for 25% of illitic clay, montmorillonite and glass powder. Densification concerning probes with sludge ashes alone does not occur with kaolin. Experimental data were adjusted to exponential relationships between compressive strengths and densities for every composition, and also to a general equation for all probes. The apparent density obtained was adjusted to a non-linear dependence with temperature, leading to a maximum in density and permitting calculating the temperature of occurrence of this maximum. The adjustment was not possible for probes containing kaolin, requiring presumably higher temperatures to densify. Water absorption has low values for ashes or kaolin probes, intermediate values for illite and powdered flat glass probes and high values for montmorillonite probes. Excepting with kaolin, ceramic materials with better characteristics than sludge ashes without additives were obtained at lower treatment temperatures.     

Mining and corruption

This study examines the links between mineral dependency and corruption. Specifically, it develops a cross-section econometric model that estimates the effects of per capita income, fuel exports, non-fuel exports, and average per unit value of mineral exports on corruption.