El Niño Caused Collapse of the Sábalo Fishery (Prochilodus lineatus, Pisces: Prochilodontidae) in a South American River

El Niño is well known to affect marine fishery. The Southern Oscillation, however, may also have a strong effect on riverine fish production in floodplains via its effect on river discharge. In years with high river discharges larger parts of the floodplain are inundated, increasing the surface area of suitable nursery grounds for young fish stock. In this way high river discharges are thought to have a positive effect on fish production, while low discharges are thought to have a negative effect. The collapse of the sábalo fishery in the Pilcomayo River in Bolivia, for instance, can be attributed to the 1990–1995 El Niño event and subsequent overexploitation of the fish stocks.     

Effects of previous sublethal pulse to ammonium nitrate on mortality and total length on Epidalea calamita larvae

Ammonium nitrate is one of the most widespread contaminants related with the viability of natural amphibian populations. In this study we have evaluated in terms of mortality and total length the effects that a previous sublethal pulse to ammonium nitrate generates in Epidalea calamita. Experiments were divided in two phases. In the first one, tadpoles were exposed to two different treatments, with and without a low ammonium nitrate concentration (22 mg NH₄NO₃ L⁻¹). The second phase consisted in static toxicity experiments from both origin treatments with five different nominal concentrations (0, 22, 45, 90 and 180 mg NH₄NO₃ L⁻¹). Results showed that tadpoles that had experienced a previous sublethal exposure showed a negative effect on survival (57% of reduction in the LC₅₀ value) and total length, throughout an increase in their sensitivity. These results could help us to understand the situation of amphibian populations inhabiting aquatic ecosystems exposed to discontinuous and variable pulses of pollutants.     

Spectroscopic Raman study of sulphate precipitation sequence in Rio Tinto mining district (SW Spain)

Acidic waters and sulphate-rich precipitates are typical by-products of mining activity such as in Rio Tinto (Huelva, SW Spain). This river drains pyrite mines situated in the Iberian Pyrite Belt which have been in operation since the Bronze Age and probably constitutes the oldest continuously operating mining activity over the world. In the present work, we have used Raman spectroscopy to study a wide range of natural mineral samples collected at Rio Tinto which origin is related to evaporation and mineral transformation processes in a wet and extreme acidic environment. In addition, we simulated the phenomenon of mineral precipitation in controlled conditions by using a simulator developed at the laboratory evaporating natural water collected at Rio Tinto. Also, a series of experiments using the same waters as small droplets have been carried out using micro-Raman technique. The droplets were placed on substrates with different chemical composition and reactivity. The results reveal that the precipitation sequence occurred in Rio Tinto mainly comprises copiapite and coquimbite group minerals followed by several other low hydrated iron sulphates. The experiments carried out on droplets allow estimating with higher accuracy the precipitation sequence.     

An Evaluation of the LPG Vehicles Program in the Metropolitan Area of Mexico City

ABSTRACT

The environmental agency in the metropolitan area of Mexico City has launched a program to introduce more energy-efficient modes of transport, one of which is the use of alternative and less polluting fuels. With that perspective in mind, a liquefied petroleum gas (LPG) fleet of vehicles is exempt of the mandatory "one day without a car" program if the emission of pollutants is below the standard authorized for that specific purpose. Today, about 28,000 light-duty vehicles and heavy-duty trucks circulate in the area, most of them as aftermarket converted vehicles. In this work, we evaluated regulated exhaust emission and other parameters on 134 representative vehicles of that fleet. From the data obtained, an estimate of emission factors and their contribution to the global emission in the metropolitan area is provided. It is concluded that more than 95% of the in-use vehicles using LPG presented regulated emissions which exceeded in one or more the environmental regulations values required for certification. The poor maintenance of the vehicles and the type of conversion kit installed could be the culprits of the results obtained.     

Spain's greatest and most recent mine disaster

On 25 April 1998, the mineral waste retaining wall at the Swedish-owned pyrite mine at Aznalcóllar (Seville, Spain) burst, causing the most harmful environmental and socio-economic disaster in the history of the River Guadiamar basin. The damage was so great that the regional government decided in May 1998 to finance a comprehensive, multidisciplinary research initiative with the objective of eradicating or at least minimising all of the negative social, economic and environmental impacts. This paper utilises a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis to identify eight strategic measures aimed at providing policymakers with key guidelines on implementing a sustainable development model, in a broad sense. Empirical evidence, though, reveals that, to date, major efforts to tackle the negative impacts have centred on environmental concerns and that the socio-economic consequences have not been completely mitigated.     

Production and Characterization of Bioplastics Obtained by Injection Moulding of Various Protein Systems

Bioplastic materials from renewable polymers, like proteins, constitute a highly interesting field for important industrial applications such as packaging, agriculture, etc., in which thermo-mechanical techniques are increasingly being used. This study assesses bioplastic materials produced by injection from blends previously prepared in a batch mixer using various protein concentrates and isolates. A mixing time of 5 min has been selected in order to ensure correct homogenous blends. A comparison between different protein-based specimens was performed by dynamic mechanical thermal analysis, tensile strength, water uptake and transmittance tests. The comparison reveals that the protein nature and the percentage of plasticizer lead to bioplastics with different properties and, consequently, different applications. Protein concentrates and isolates, wastes and surpluses from the food industry, may be useful for producing bioplastics with suitable mechanical properties and processability, as well as biodegradability, by means of suitable mixing and injection moulding conditions.     

Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment

The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na(2)SO(4)+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al(2)O(3) content of the fly ash. The diffusion of SO(4)(2-), Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition.     

Evidence of differences in the biotransformation of organic contaminants in three species of freshwater invertebrates

Acute static bioassays were performed using three freshwater invertebrate species (the oligochaete Lumbriculus variegatus, the fingernail clam Sphaerium corneum and the larvae Chironomus riparius) exposed separately to a variety of 14C radiolabelled contaminants. The aim of this work was to investigate if the chemicals remained as parent compounds after the treatments. Chemicals used were 2,4-dichlorophenol; 2,4,5-trichlorophenol; pentachlorophenol; pyrene; Fenpropidin, and Trifluralin. Homogenates of the whole body tissue of each organism were prepared and total radioactivity was measured. Contaminants were then extracted into organic solvents and analysed by high-pressure liquid chromatography techniques. Chromatograms showed that most of the substances extracted were present as parent compounds in S. corneum and in L. variegatus. In contrast, for C. riparius a low proportion of the chemicals was recovered as parent compounds. These results suggest that different metabolic processes could take place in the different species.     

Sex attractant of an arctiid moth (Utetheisa ornatrix): A pulsed chemical signal

Summary The sex attractant pheromone produced by the female of the moth Utetheisa ornatrix was shown to contain Z, Z, Z-3, 6, 9-heneicosatriene. The compound, whose structure was confirmed by synthesis, proved active in electroantennogram and field bioassays. Pheromone emission occurs discontinuously, in the form of short pulses (pulse repetition rate=1.5±0.2 pulses/s). It is argued that such temporal patterning — which had not previously been demonstrated for an airborne chemical signal — can provide close-range orientation cues to the male moth as it seeks out the female.