Effects of soil attributes and straw accumulation on the sorption of hexazinone and tebuthiuron in tropical soils cultivated with sugarcane

Brazil is the largest sugarcane producer in the world in which hexazinone (3-cyclohexyl-6-dimethylamino-1-methyl-1,3,5-triazine-2,4-dione) and tebuthiuron (1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea) are heavily used. Sugarcane harvesting is changing from the manual system with previous straw burning to the mechanized system without straw burning. The lack of burning results in soil organic carbon accumulation mainly in clayey soils, which should affect herbicides availability and fate. Therefore, we evaluated sorption of these herbicides in soil samples with and without straw burning. Both herbicides presented low apparent sorption coefficients (mean K_d,app= 0.6 and 2.4 L kg^?1 for hexazinone and tebuthiuron, respectively), suggesting that they may leach to groundwater. Moreover, their sorption correlated primarily with soil organic carbon (SOC), but iron oxide contents extracted with ammonium oxalate (Fe₂O₃^AOX) also affected it (K_d,app = ?0.228 + 0.0397 SOC + 0.117 Fe₂O₃^AOX for hexazinone and K_d,app = ?1.407 + 0.201 SOC + 0.348 Fe₂O₃^AOX for tebuthiuron). Soil organic carbon accumulation due to straw maintenance in the field positively affected sorption of both herbicides, but its effects were not enough to classify them as “non-leachers.”     

The new challenges of end-of-life tyres management systems: A Spanish case study

Directive 2008/98/EC released by the European Union represents a significant step forward in all relevant aspects of waste management. Under the already established, extended produced responsibility (EPR) principle, new policies have been enunciated to continuously achieve better overall environmental performance of key products throughout their life phases. This paper discusses how the directive is being articulated in Spain by the main integrated management system (IMS) for end-of-life (EOL) tyres since its creation in 2006. Focusing on the IMS technological, economic and legal aspects, the study provides a global perspective and evaluation of how the IMS is facing the current issues to resolve, the new challenges that have appeared and the management vision for the coming years.     

Agronomic characterisation of different types of sewage sludge: Policy implications

Spain is one of the main municipal sewage sludge producers of Europe. This paper aims to agronomically characterise different types of sewage sludge stabilised by different methods (anaerobically digested, composted, and pelletised) and deliver policy recommendations from the results of this characterisation. Anaerobic sewage sludge quality is found to be better in plants with a lower volume of water processing. Composted sludge shows the best quality from a heavy metal point of view, but its low available nitrogen content increases the input of heavy metals when spread, as compared to digested or pelletised sludge. Pelletised sludge has higher heavy metal content than anaerobically digested sludge. Despite the good quality of the sludges, future regulations, especially with regard to Cd levels, will limit the use of this waste in agriculture.     

Personal ammonia sensor for industrial environments

The realisation of an opto-chemical ammonia sensor suitable for personal monitoring tasks is described, comprising a cyanine dye immobilised in a microporous glass thin film. The fabrication of sensor platforms incorporating embossed grating couplers provides a compact optical design with effective waveguiding characteristics, resulting in reversible ammonia sensitivity in the 5-100 ppm range in under 2 min. Cross-sensitivity of sensor response with water and other potential interferents is considered.     

Midnight at the oasis: does restoration change the rigs-to-reefs debate in the North Sea?

ABSTRACT

In the North Sea, many oil and gas fields will reach the end of their productivity and their associated structures will be decommissioned. OSPAR decision 98/3 prescribes removal of all disused offshore structures as the only acceptable decommissioning option. This policy is the legacy of the 1995 Brent Spar incident, which resulted in the current dominant discourse of ‘Hands off the Oceans,’ ruling out the conversion of oil and gas rigs into artificial reefs (Rigs-to-Reefs (RtR)). The shift from a conservation to a restoration paradigm could open up the RtR debate. In this paper, a discourse analysis is carried out to discern whether and how ideas about RtR and ecosystem restoration are articulated to challenge the dominant ‘Hands off the Oceans’ discourse and thereby bring about change in North Sea decommissioning policy. A discourse analytic framework is applied to elucidate whether an ‘RtR as Restoration’ discourse can be distinguished and how competing claims are presented in the various storylines. Our analysis shows an ‘RtR as Restoration’ discourse, consisting of four different storylines. Given the fragmented nature of this discourse, the ‘RtR as Restoration’ discourse will not overcome the dominant ‘Hands off the Oceans’ discourse.     

An optimized airfoil geometry for vertical-axis wind turbine applications

ABSTRACT

In this work, a new airfoil shape optimized for vertical-axis wind turbine applications is proposed. Different airfoil shapes have been analyzed with JavaFoil, a panel method software. Then, the results from the analysis have been used to optimize the performance of the new airfoil shape. Afterward, Computational Fluid Dynamics (CFD) simulations of the proposed airfoil, UO-17-LDA, are run for different angles of attack to provide insight into the flow field and the mechanisms related to this increase in performance. The UO-17-LDA airfoil presents a high lift-to-drag ratio and a delayed stall angle with respect to the original FX-63-137 airfoil, making it suitable for vertical-axis wind turbine applications. This increase in performance has been verified by comparing two VAWT designs with the original and the proposed airfoil using a double-multiple streamtube model. Finally, the practicality of JavaFoil for the comparison of different airfoil geometries has been verified, as it is capable of obtaining results for a wide number of flow conditions in small computational times and with a user-friendly interface. Nevertheless, the results diverge from the actual solution for high angles of attack (beyond stall). Hence, the time and effort required to perform CFD simulations is justified to gain insight into the actual behavior of a particular airfoil, as well as to obtain a richer analysis of the flow field and the mechanisms related to the airfoil performance.     

The Management of a Large Mediterranean Reservoir: Storage Regimens of the Yesa Reservoir,Upper Aragon River Basin,Central Spanish Pyrenees

Agriculture in Mediterranean countries is mainly based upon the irrigation of productive areas in the lowlands. For this reason, it is necessary to store large volumes of water in reservoirs located in mountain headwaters. These reservoirs have a relatively simple regimen of storage, increasing the water stored during the wet season (from October until May) and reaching the maximum volume shortly before the beginning of the hot, very dry season, when the water is released. This paper considers the storage regimen (inflow and outflow) of the Yesa Reservoir in the Spanish Pyrenees as an example of management of a large reservoir in a mountain Mediterranean environment, subject to a strong interannual variability. On average, the highest water storage level is achieved by retaining the high flows of the Aragón River in autumn and spring. Nevertheless, the irregularity of rainfalls and the existence of changes in the hydrological regimen lead to changes in the patterns of reservoir filling. Two patterns were identified in the Yesa Reservoir: (1) a quick increase of the stored volume in autumn, a stabilization in winter, and a new increase in spring; and (2) a continuous increase from October until May. These patterns are distributed in time over different periods since the construction of the reservoir in 1959, demonstrating the adjustment of the reservoir management to changes in the hydrological regimen.     

Contrasting physiological responses of dwarf sea-lavender and marguerite to simulated sea aerosol deposition

Plants of two wild native species from littoral areas, marguerite [Argyranthemum coronopifolium (Willd.) C.J. Humphries] and dwarf sea-lavender [Limonium pectinatum (Aiton) O. Kuntze], grown in an unheated plastic greenhouse, were sprayed 2 to 3 min per day over a 7-d period with different aqueous solutions containing (i) an anionic surfactant (S1); (ii) a solution simulating the composition of sea aerosol (S2); (iii) a solution simulating sea aerosol with anionic surfactant (S3), and (iv) deionized water alone (control). The plant resistance to sea aerosol and the ability to recover from treatments were studied. By the end of the spraying period, marguerite showed a significant reduction in growth compared with control. However, most of the growth parameters were significantly unaffected in dwarf sea-lavender when plants were treated with sea aerosol containing surfactant. Measurements of water relations variables in marguerite showed a slight decrease in leaf turgor potential after spraying with sea aerosol containing surfactant. The surfactant enhanced the foliar absorption of salt in marguerite plants, inducing reductions in leaf stomatal conductance and causing such damage in the photosynthetic apparatus that the level of net photosynthesis decreased and had not recovered by the end of the experiment. The treatments had no effect on leaf stomatal conductance and photosynthesis rate in dwarf sea-lavender plants. The response of the species studied to sea aerosol was related to the degree of salinity tolerance. Although both species are wild native plants from littoral areas, marguerite is not salt tolerant and was the most sensitive to the sea aerosol treatments, while dwarf sea-lavender, a halophyte species, was more efficient at decreasing the toxic salt content of the tissues as its growth and ornamental characteristics were not affected.     

Analysis of the exterior colour of agroindustrial buildings: a computer aided approach to landscape integration

The visual and aesthetic aspects of any object are defined by its colour, form, line and texture, to which might be added compositional reference elements such as scale and, in the case of three dimensional scenes, spatial character. This paper investigates one of these colour and proposes a method for predicting the value of a building's integration into the landscape. Based on psychological aspects, the method uses computers to analyse and measure the pertinent attributes. The designer can analyse visual elements in terms of the properties that define them. For example, colour, the subject of this paper, is defined by its hue, saturation and lightness. Tables are proposed to study the relationship between buildings and their background using computers. This paper offers a tool, based on the digital examination of scenes and on people's integration preferences with respect to agroindustrial buildings, which it is hoped will help project designers select appropriate colour schemes.     

Validation of isotope signatures in sediments affected by anthropogenic inputs from uranium series radionuclides

This paper aims to show the usefulness of 226Ra/228Ra activity ratios and confirm the possibility of using 230Th/232Th activity ratios as chronological markers in sediment cores from an estuarine system strongly contaminated by discharges from non-nuclear industries (fertiliser plants). The validation was carried out using an independent, well-established dating technique based on the analysis of the 137Cs fallout profile, which comprises the same time interval as that covered by both isotope ratios. The advantage of using the 226Ra/228Ra activity ratio profile instead of the Th-isotope profile is that determination can be accomplished with a non-destructive, simpler and less time-consuming technique, because both Ra isotopes can be determined by gamma-ray spectrometry.