Influence of hydrodynamic conditions on the production and fate of Posidonia oceanica in a semi-enclosed shallow basin (Stagnone di Marsala, Western Sicily)

An integrated approach using hydrodynamic and transport numerical models, lepidochronology and stable isotope analysis was used to investigate how local hydrodynamic conditions influence the primary production and fate of the seagrass Posidonia oceanica in a Mediterranean semi-enclosed marine system (Stagnone di Marsala). The water mass exchange aptitude of different sectors of the basin was analysed, and data collected were used to select two sectors (colonized by Posidonia oceanica showing the lowest and highest water exchange values) for biological analyses. According to the mean dispersal coefficient differences simulated by the hydrodynamic model, growth rate and primary production of P. oceanica differed between sectors, with average values lower in the central sector where water exchange is lower than in the southern sector. Although P. oceanica coverage and primary production were higher in the southern sector, carbon and nitrogen stable isotope analysis suggests that the transfer of seagrass organic matter to higher trophic levels of the food web was higher in the central sector. The possibility of a link between hydrodynamism, production and fate of organic matter is proposed to explain the observed patterns.     

Hydrocarbons in particulate samples from wildfire events in central Portugal in summer 2010

In summer 2010, twenty eight(14 PM_(2.5)samples plus 14 samples PM_(2.5–10)) smoke samples were collected during wildfires that occurred in central Portugal. A portable high-volume sampler was used to perform the sampling, on quartz fibre filters of coarse(PM_(2.5–10)) and fine(PM_(2.5)) smoke samples. The carbonaceous content(elemental and organic carbon) of particulate matter was analysed by a thermal–optical technique. Subsequently, the particulate samples were solvent extracted and fractionated by vacuum flash chromatography into three different classes of organic compounds(aliphatics, polycyclic aromatic hydrocarbons(PAHs) and carbonyl compounds). The organic speciation was performed by gas chromatography–mass spectrometry(GC–MS). Emissions were dominated by the fine particles, which represented around 92% of the PM_(10). A clear predominance of carbonaceous constituents was observed, with organic to elemental carbon(OC/EC)ratios ranging between 1.69 and 245 in both size fractions. The isoprenoid ketone6,10,14-trimethyl-2-pentadecanone, a tracer for secondary organic aerosol formation, was one of the dominant constituents in both fine and coarse particles. Retene was the most abundant compound in all samples. Good correlations were obtained between OC and both aliphatic and PAH compounds. Pyrogenic processes, thermal release of biogenic compounds and secondary processing accounted for 97% of the apportioned PM_(2.5)levels.     

Pyrolysis of tyres. Influence of the final temperature of the process on emissions and the calorific value of the products recovered

A study was made of the pyrolysis of tyre particles, with the aim of determining the possibilities of using the products resulting from the process as fuel. Three final temperatures were used, determined from thermogravimetric data. The design of the experiment was a horizontal oven containing a reactor into which particles of the original tyre were placed. After the process, a solid fraction (char) remained in the reactor, while the gases generated went through a set of scrubbers where most of the condensable fraction (oils) was retained. Finally, once free of this fraction, the gases were collected in glass ampoules. Solid and liquids fractions were subjected to thermogravimetric analyses in order to study their combustibility. The gas fraction was analysed by means of gas chromatography to establish the content of CO, CO2, H2 and hydrocarbons present in the samples (mainly components of gases produced in the pyrolysis process). A special study was made of the sulphur and chlorine content of all the fractions, as the presence of these elements could be problematic if the products are used as fuel. Tyre pyrolysis engenders a solid carbon residue that concentrates sulphur and chorine, with a relatively high calorific value, although not so high as that of the original tyre. The liquid fraction produced by the process has a high calorific value, which rises with the final temperature, up to 40 MJ/kg. The chlorine content of this fraction is negligible. Over 95% of the gas fraction, regardless of the final temperature, is composed of hydrocarbons of a low molecular weight and hydrogen, this fraction also appearing to be free of chlorine.     

Particulate matter in the indoor and outdoor air of a gymnasium and a fronton

An indoor/outdoor monitoring programme of PM₁₀ was carried out in two sports venues (a fronton and a gymnasium). Levels always below 50 μg m^?3 were obtained in the fronton and outdoor air. Due to the climbing chalk and the constant process of resuspension, concentrations above 150 μg m^?3 were registered in the gymnasium. The chalk dust contributed to CO₃ ^2? concentrations of 32?±?9.4 μg m^?3 in this sports facility, which represented, on average, 18 % of the PM₁₀ mass. Here, the carbonate levels were 128 times higher than those registered outdoors. Much lower concentrations, around 1 μg m^?3, were measured in the fronton. The chalk dust is also responsible for the high Mg²⁺ concentrations in the gym (4.7?±?0.89 μg m^?3), unfolding a PM₁₀ mass fraction of 2.7 %. Total carbon accounted for almost 30 % of PM₁₀ in both indoor spaces. Aerosol size distributions were bimodal and revealed a clear dependence on physical activities and characteristics of the sports facilities. The use of climbing chalk in the gymnasium contributed significantly to the coarse mode. The average geometric mean diameter, geometric standard deviation and total number of coarse particles were 0.77 μm, 2.79 cm^?3 and 28 cm^?3, respectively.     

Raptor ecotoxicology in Spain: a review on persistent environmental contaminants

Initial studies on the pressure from environmental contaminants on raptor populations in Spain date back to the 1980s, and they have been carried out from a range of viewpoints using a range of sentinel raptor species. However, there is no national monitoring scheme, and therefore the research carried out has been sporadic both spatially and temporally. The exposure to metals has not varied over time, except in the case of lead, whose concentration in eggs and tissues has diminished. In general, the concentrations of metals detected in raptor samples from Spain are generally low and not sufficient to produce toxic effects. Excepting DDT and DDE, most organochlorine-based pesticides in raptors from Spain have diminished over the last 2 decades. The concentrations of DDE found in the eggs of various species could in part explain problems in the reproductive success of raptors in Spain.     

Spatial pattern of ozone injury in Aleppo pine related to air pollution dynamics in a coastal-mountain region of eastern Spain

In eastern Spain, studies combining the tracking and meso-scale circulations of air pollutants with the evaluation of their effects on plants have been undertaken since 1994. Meso-scale processes are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean area. The first results of these field surveys show that in 1994, 1995 and 1996, the distribution pattern of ozone visual injury (chlorotic mottle) in Pinus halepensis correlated with the penetration of pollutants transported by the sea-breeze into coastal valleys of Castellón (eastern Spain). In this tree species, longer needles are associated with higher chlorotic mottle, and ozone injury seems to be among the factors affecting needle retention and crown transparency.     

Properties and erosional response of soils in a degraded ecosystem in Crete (Greece)

To study desertification processes relating to soil erosion, a climatological and altitudinal gradient from south to north was selected in Crete (Greece) and four locations were selected along the gradient. At the locations precipitation ranged from 1400 mm/year at the highest location to 400 mm/year at the lowest. All locations are affected by the actual land use: intensive grazing, small controlled fires, and abandoned agricultural terraces. Representative soil profiles were described in the field and analyzed in the laboratory, and rainfall simulation experiments in the field measured soil erosion over different soil surfaces and land uses. Data on physical and chemical properties were obtained from the soil profiles and soil hydrology, and erosion data were obtained from the rainfall simulation experiments. Soil aggregation was studied with samples taken from the soil in the rainfall simulation plots and special attention being paid to the aggregate size distribution and the water-stable microaggregation. The interaction between climatological conditions and land use seems to be the main factor controlling soil erosion. This paper describes how the expected erosion along the gradient (from the most humid to the driest site) can be affected and disturbed by specific processes derived from land use.