Simulation and Evaluation of Control Strategies for Ozone Reduction in a Complex Terrain in Southwestern Spain

During the central months of the year, southwestern Spain is under strong insolation and weak synoptic forcing, promoting the development of sea breezes and mountain-induced winds and creating recirculations of pollutants. The complex topography of the Southwestern Iberia Peninsula induces the formation of vertical layers, into which the pollutants are injected and subjected to long-distance transport and compensatory subsidence. The characteristics of these highly complex flows have important effects on the pollutant dispersion. Air pollution studies in very complex terrains require high-resolution modelling for resolving the flow dynamics. This paper shows the results obtained from using the MM5-CAMx multiscale-nested air quality model to relate the sensitivity regimes for ozone, nitrogen oxides and volatile organic compounds in an area of high geographical complexity. The article assesses the impact on the hourly and eight-hourly maximum daily ozone concentrations of four reduction strategies during two ozone pollution episodes. This analysis of the ozone response has led to a preliminary evaluation of the effectiveness of the most common control strategies: traffic, industry, mixed traffic and industry, and closure of some of the largest industries (oil and petrochemical refineries). Photochemical indicators show that ozone chemistry in southwestern Spain is strongly sensitive to NO _x . However, volatile organic compound-sensitive points are found in areas with anthropogenic influence (highways, cities and industrial parks). Our results indicate that reductions in road traffic lead to ozone reductions over large areas, whereas reductions in industrial emissions, despite sometimes showing greater decreases in the maximum hourly and eight-hourly ground-level ozone levels, lead to ozone reductions in a local area only. In the control study case, with the oil refinery and the petrochemical plants closed, decreases in ozone hourly concentrations are up to 40% higher than in the other emission control scenarios studied. This analysis provides an assessment of the effectiveness of different policies for controlling precursor emissions by comparing the modelled results for different scenarios.     

Application of Reproduction Technologies to the Conservation of Genetic Resources

Abstract: Maintaining the levels of genetic variability in captive populations of endangered species is an important objective of conservation biology. Because of the generally low sizes of captive populations, genetic drift is the main cause of loss of diversity. Several simple management rules, such as equalization of contributions from parents to the next generation, are recommended for minimizing genetic drift, but it cannot be removed completely because of the unavoidable random segregation of heterozygotes. Recent advances in reproductive technology, particularly developed for mammals, are now making a reality of the possibility of using more than one cell from a single meiosis in reproduction. With this technology it is possible to reduce or even completely cancel the genetic drift caused by segregation of heterozygotes. We evaluated the theoretical benefits of the use of such technologies to conservation biology. The effective population size can be increased enormously and, consequently, the amount of drift can be greatly reduced if manipulations in reproduction are made.     

Cd2+ adsorption on alkaline-pretreated diatomaceous earth: equilibrium and thermodynamic studies

Naturally occurring diatomaceous earth was modified by alkaline pretreatment, and its effectiveness for Cd²⁺ removal from contaminated water was investigated. Batch experiments were carried out to determine Cd²⁺ adsorption capacity and the efficiency of the sorption process under different experimental conditions. Experimental data showed good fitting to Langmuir and Freundlich isotherms models. The Cd²⁺ maximum adsorption capacity was 0.058 mmol g⁻¹ for raw diatomite and increased to 0.195 mmol g⁻¹ for alkaline-pretreated diatomite with efficiency higher than 96% (diatomite dose 2.5 g L⁻¹, pH 6). Adsorption of Cd²⁺ to alkaline-pretreated diatomite increased as the temperature increased. Thermodynamic parameters were calculated to evaluate the feasibility of the adsorption process at different temperatures. The adsorption process was spontaneous and endothermic. The interaction between Cd²⁺ ions and diatomite surface was weak enough to be considered as physical sorption, confirmed by the low value of activation energy.     

Selection of ecological indicators for the conservation, management and monitoring of Mediterranean coastal salinas

Salinas systems are artificial wetlands which are interesting from the viewpoint of nature conservation. They play an important role both as habitats for migratory waterbird species and as nodes of biotic connectivity networks. In the Mediterranean basin, where the coastal salinas are highly significant as alternative and complementary habitats for waterbirds, a process of abandonment occurs, and many seminatural systems of this kind are disappearing. This abandonment is having serious consequences for migratory bird populations and for the ecological role these play. In the present paper, this group of waterbird species has been used to evaluate these wetlands for conservation purposes. We have developed a methodological approach for the selection of ecological indicators for the conservation and management of these Mediterranean habitats and waterbird assemblages, the main consumers therein. The stepwise procedure developed constitutes a practical tool for this task. Application thereof enabled us to differentiate the habitats available for the waterbirds and to identify the biotic and abiotic indicators for the maintenance and management of the salina ecosystems. These variables can then be incorporated into monitoring programs.     

Assessing the impact of petrol stations on their immediate surroundings

This paper describes a novel methodology for evaluating the extent to which petrol stations affect their surroundings. The method is based on the fact that the ratio of the concentrations of aliphatic and aromatic hydrocarbon pollutants in the air of the petrol stations and their surroundings (basically determined by vapor emissions from unburned gasoline) differs from the ratio found in urban air, which is mainly influenced by traffic emissions. Bearing this in mind, the spatial limit of influence of petrol stations in any direction would be the first point, moving away from the station, where the ratio becomes equal to the urban background ratio. Application of the methodology involves multipoint measuring campaigns of the air at the studied petrol station and built-up area in general and processing the data with software capable of providing isoconcentration contours. The procedure should help local authorities in terms of land management, so that a “belt” can be established around petrol stations where housing or vulnerable populations and activities such as those in schools, hospitals and community centers should be restricted.     

Spatial distribution of lindane in topsoil of Northern France

Lindane is a persistent organochlorine insecticide and the use of this insecticide in agriculture was banned in France in 1998. In this study we investigated the concentrations of lindane in topsoil in Northern France and used robust geostatistics to map the geographical distribution of lindane. The study was based on a 16 km × 16 km grid covering an area of ca 25 000 km². Lindane was found in all soils, even those from non-agricultural-application areas. Very low ratios of α-/γ-HCH and δ-/γ-HCH suggested that a long time had passed since technical HCH was used in the studied area, or that emission sources of lindane were still present. A strong gradient in lindane concentration was observed, with the highest lindane concentrations in an area located in the northern region. Results suggested that some of the lindane observed in the high concentration area may have come from volatilization of old lindane applied to intensively cultivated areas, which was then transported by prevailing winds coming from the south-west and deposited in a densely inhabited depression.     

Identification and chemical characterization of industrial particulate matter sources in southwest Spain

A detailed physical and chemical characterization of coarse particulate matter (PM10) and fine particulate matter (PM2.5) in the city of Huelva (in Southwestern Spain) was carried out during 2001 and 2002. To identify the major emission sources with a significant influence on PM10 and PM2.5, a methodology was developed based on the combination of: (1) real-time measurements of levels of PM10, PM2.5, and very fine particulate matter (PM1); (2) chemical characterization and source apportionment analysis of PM10 and PM2.5; and (3) intensive measurements in field campaigns to characterize the emission plumes of several point sources. Annual means of 37, 19, and 16 microg/m3 were obtained for the study period for PM10, PM2.5, and PM1, respectively. High PM episodes, characterized by a very fine grain size distribution, are frequently detected in Huelva mainly in the winter as the result of the impact of the industrial emission plumes on the city. Chemical analysis showed that PM at Huelva is characterized by high PO4(3-) and As levels, as expected from the industrial activities. Source apportionment analyses identified a crustal source (36% of PM10 and 31% of PM2.5); a traffic-related source (33% of PM10 and 29% of PM2.5), and a marine aerosol contribution (only in PM10, 4%). In addition, two industrial emission sources were identified in PM10 and PM2.5: (1) a petrochemical source, 13% in PM10 and 8% in PM2.5; and (2) a mixed metallurgical-phosphate source, which accounts for 11-12% of PM10 and PM2.5. In PM2.5 a secondary source has been also identified, which contributed to 17% of the mass. A complete characterization of industrial emission plumes during their impact on the ground allowed for the identification of tracer species for specific point sources, such as petrochemical, metallurgic, and fertilizer and phosphate production industries.     

The copper and aluminum industries: A review of structural changes

In this article the evolution of the aluminium and copper industries is examined, with a view to deriving policy options open to Third World copper producers, which face a declining rate in the growth of consumption. Market structure, company behaviour and performance are analysed for both industries. The impact of energy and general economic crisis in copper and aluminium industries is assessed and market concentration trends are discussed. We conclude that Third World copper producers must change their basic orientation and become seriously involved in market development.     

A NEW APPROACH FOR ESTIMATING IRRIGATION CONVEYANCE LOSSES AND THEIR ECONOMIC EVALUATION1

ABSTRACT: In this paper a new methodology for estimating conveyance efficiency within irrigation systems is presented. Based on statistical analysis of daily water releases from the source of supply and deliveries to the farmers in an irrigation district in Mexico, a linear model is obtained for estimating conveyance efficiency and two component factors. One of these factors points out the relative importance of the operational losses (i.e., losses due to water management), and the second shows the importance of the fixed losses which can be attributed to the average flow through the canal network without variations. In the last part of this paper, an analysis of the expected benefits and costs accruing from system improvement permits derivation of a decision rule which may be used for analyzing the economic feasibility of lining in-place canals.