Chemical compounds of the foraging recruitment pheromone in bumblebees

When the frenzied and irregular food-recruitment dances of bumblebees were first discovered, it was thought that they might represent an evolutionary prototype to the honeybee waggle dance. It later emerged that the primary function of the bumblebee dance was the distribution of an alerting pheromone. Here, we identify the chemical compounds of the bumblebee recruitment pheromone and their behaviour effects. The presence of two monoterpenes and one sesquiterpene (eucalyptol, ocimene and farnesol) in the nest airspace and in the tergal glands increases strongly during foraging. Of these, eucalyptol has the strongest recruitment effect when a bee nest is experimentally exposed to it. Since honeybees use terpenes for marking food sources rather than recruiting foragers inside the nest, this suggests independent evolutionary roots of food recruitment in these two groups of bees.     

Thermogravimetric kinetic analysis and pollutant evolution during the pyrolysis and combustion of mobile phone case

The increase in electronic waste, including cellular telephones, worldwide is a worrying reality. For this reason, urgent action on the management of these wastes is necessary within a framework that respects the environment and human health. Mobile phone components can be physically segregated through grinding at the dismantling sites, in order to reuse or reprocess (via chemical or physical recycling) the recovered plastics and valuable metals. A kinetic study of the thermal decomposition of a mobile phone case has been carried out under different conditions by thermogravimetry. Several experiments were performed in a nitrogen atmosphere (pyrolysis runs) and also in an oxidative atmosphere with two different oxygen concentrations (10% and 20% oxygen in nitrogen). Dynamic runs and dynamic+isothermal runs have been carried out to obtain much decomposition data under different operating conditions. Moreover some TG-MS runs were performed in order to better understand the thermal decomposition of a mobile phone case and identify some compounds emitted during the controlled heating of this material. A scheme of two independent reactions for pseudocomponents has been proposed for the pyrolysis process. For the combustion runs, the scheme proposed includes two pyrolytic reactions competing with other two reactions with formation of an intermediate residue, and finally the reaction of oxidation/burning of the intermediate residue. Furthermore, pyrolysis and combustion runs at 500 °C in a horizontal laboratory furnace were carried out. More than 50 compounds, including carbon oxides, light hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) have been identified and quantified. The main semivolatile compounds detected were phenol and styrene. Furthermore, polychlorodibenzo-p-dioxin and polychlorodibenzofurans (PCDD/Fs) and dioxin-like PCBs produced were analyzed. In the combustion run, PCDDs were obtained in higher amounts than PCDFs and HxCDD was the most emitted homologue.     

Thermal decomposition of electronic wastes: mobile phone case and other parts

Pyrolysis and combustion runs at 850°C in a horizontal laboratory furnace were carried out on different parts of a mobile phone (printed circuit board, mobile case and a mixture of both materials). The analyses of the carbon oxides, light hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorodibenzo-p-dioxin, polychlorodibenzofurans (PCDD/Fs), and dioxin-like PCBs are shown. Regarding semivolatile compounds, phenol, styrene, and its derivatives had the highest yields. In nearly all the runs the same PAHs were identified, naphthalene being the most common component obtained. Combustion of the printed circuit board produced the highest emission factor of PCDD/Fs, possibly due to the high copper content.     

Dermal exposure to pesticides in greenhouses workers: discrimination and selection of variables for the design of monitoring programs

Dermal exposure to pesticides is one of the main sanitaryproblems which greenhouses workers face. With the dual aimsof establishing both the body part that receives the greatestexposure and the variable that has greatest influence on this exposure level, 22 pesticide application trials were performed. Trials were carried out in different greenhouse vegetable crops,using different pesticides and different spray diameters from the spray gun. In order to determine dermal exposure, the wholebody method was used. Pieces of the applicator suit were subject to an extraction procedure and their pesticide contentdetermined using GC-NPD analysis. Multivariate analysis were applied to the data obtained. Principal component analysis showed that all trials produced a high exposure level on lowerleft leg and lower right leg. Cluster analysis distinguished between three sample groups. The most and the least affectedparts were clearly distinguished. Discriminant analysis indicated that the thin drop size of the spray gun is responsible for both the differences between groups and the minimum or maximum exposure level measured on the applicatorsuit. Therefore, selecting the variables, lower legs and thindrop size, is considered fundamental in designing programs formonitoring pesticide exposure.     

Vertical concentration gradients of volatile organic compounds in two NS-oriented street canyons

Diffusive samplers were used to measure the vertical concentrations of benzene, toluene, n-hexane, cyclohexane, ethylbenzene and o-, m- and p-xylenes on both sides of two NS-oriented street canyons in Murcia (Spain) during a 5-day period. Non-dimensional relationships of concentration and height were calculated in order to study the behaviour of their concentration vertical profiles. The results show that the vertical profiles of benzene, toluene, n-hexane and cyclohexane concentrations were similar in both streets and on both sides of each street. Some differences were found in vertical profiles between streets and sides for ethylbenzene and xylenes, probably due to their higher affinity for adsorption into building materials. The similarities found for the first set of VOCs suggest that the dynamics of the dispersion was the same for both streets and was mainly influenced by microscale thermal effects. Finally, the concentration measurements of benzene, toluene, n-hexane, cyclohexane, and ethylbenzene were adjusted to expressions in the form c?=?c ₀(h/h ₀) ^A , and a regression coefficient R ²?=?0.962 (p?=?0.0000) was obtained. The decreasing concentration of these compounds with height should be taken into account when assessing population exposure to these pollutants.     

Biodiversity and food security: from trade-offs to synergies

Regional Environmental Change -     

Identification of copper sources in urban surface waters using the principal component analysis based on aquatic parameters

The goal of this work was to identify the sources of copper loads in surface urban waters using principal component analysis under the aquatic parameters data evaluation approach. Water samples from the Irai and Iguacu rivers were collected monthly during a 12-month period at two points located upstream and downstream of a metropolitan region. pH, total alkalinity, dissolved chloride, total suspended solids, dissolved organic matter, total recoverable copper, temperature, and precipitation data provided some reliable information concerning the characteristics and water quality of both rivers. Principal component analysis indicated seasonal and spatial effects on copper concentration and loads in both environments. During the rainy season, non-point sources such as urban run-off are believed to be the major source of copper in both cases. In contrast, during the lower precipitation period, the discharge of raw sewage seems to be the primary source of copper to the Iguacu River, which also exhibited higher total metal concentrations.