Measurements of semivolatile and particulate polycyclic aromatic hydrocarbons in a bus station and an urban tunnel in Salvador,Brazil

Motor vehicles constitute a significant source of polycyclic aromatic hydrocarbon (PAH) emissions to the atmosphere. Particle-phase priority pollutant PAH concentrations and total suspended particle mass (TSP) were measured in the Lapa bus station and the Americo Simas Tunnel, located in the city of Salvador, Brazil. Separate samples were collected at the bus station at different times of the day, including rush- and non-rush-hour periods. The highest concentrations for nearly all 16 priority PAHs measured at the bus station were observed at 18:30 h, with chrysene showing the highest mean value (26.6 ng m-3). The highest average PAH concentrations measured in the tunnel were observed for pyrene (79.4 +/- 11.5 ng m-3) followed by fluoranthene (39.0 +/- 5.2 ng m-3) and chrysene (28.0 +/- 4.17 ng m-3). TSP levels reached 423 micrograms m-3 in the bus station, and values as high as 2 mg m-3 in the tunnel. The measured Salvador tunnel PAH profiles are very similar to the Salvador bus station profiles, and are similar to PAH profiles reported for the Kojouike Tunnel, located in Kurashiki City, Japan, and the Caldecott Tunnel, located in Berkeley, California.     

GROUND WATER SOLUTE TRANSPORT,OPTIMAL REMEDIATION PLANNING,AND DECISION MAKING UNDER UNCERTAINTY1

ABSTRACT: A groundwater quality modeling advisory system has been developed for the U.S. Air Force for use in investigating remediation alternatives for the cleanup of subsurface contamination. The system is capable of accounting for uncertainty, not only in the prediction of solute transport but also in the optimization of the remediation scheme through chance constraints. The system guides users in the selection of appropriate transport models through an algorithm independently tested with machine learning codes. An application to Hill Air Force Base, Utah, is presented for which different pump-and-treat strategies are considered: the results are evaluated in terms of the cumulative distribution of the contaminant concentration for each case and the tradeoff relationship between the cost of remediation and the probability that the remediation strategy exceeds an established maximum allowable contaminant concentration.     

Change in environmental stability and the use of resources on small islands: The case of Formentera,Balearic Islands,Spain

Since the beginning of the 1960s, mass tourism has been the most important menace to the environmental stability of fragile and vulnerable Mediterranean microinsular systems. The socioeconomic changes introduced by tourism have produced important variations in the use of resources, including land. The result usually has been an increase in the level of artificiality of the territory, particularly in coastal areas. The intensity and frequency of change in the use of resources and the induced changes in the level of artificiality may be used as an estimation of environmental stability. The northern area of Formentera, Balearic islands, Spain, being the most environmentally important area of the island and simultaneously the most threatened by mass tourism development, has been chosen as a study case. Forty types of vegetation and land use have been estimated and mapped in the area. The stability level of each land use type has been estimated, before and after the development of tourism, and the main environmental processes have been identified. An attempt is made to predict some future trends and their variations.     

A rainwater quality monitoring network: a preliminary study of the composition of rainwater in Galicia (NW Spain)

A network consisting of 17 sampling stations strategically distributed in the geographical area of Galicia (NW Spain) was set up in January 1999 in order to monitorice the ionic rainwater quality in this Spanish region which has an area approximately 29.575 km(2) and a population of 2.8 million. This paper presents the preliminary results of the exploratory study on the ionic rainfall composition in this area during the first year. In each rainwater sample collected chloride, sulphate, nitrite, nitrate, phosphate, sodium, potassium, magnesium, calcium and ammonium were measured, as were pH, conductivity and precipitation-volume. An univariate study according to the location of each sampling site was performed. Multivariate chemometric techniques, such as principal component analysis and cluster analysis, were applied to the complete data set (consisting of 630 observations) in order to elucidate the factors affecting the ionic composition of rainwater.     

Two-dimensional model for soil electrokinetic remediation of heavy metals. Application to a copper spiked kaolin

A two-dimensional numerical model has been developed to simulate the electrokinetic remediation of soils contaminated with heavy metals and has been validated using laboratory experiments performed with a copper spiked kaolin. The model divides the soil into compartments in a Cartesian grid and a non-conductivity barrier encloses the considered area. Basically, it consists in two main parts clearly distinguishable. The first part describes the electromigration phenomenon in the soil, which is represented by a set of electric resistors, following the Cartesian grid and using Kirchoff's laws of electricity to calculate the voltage drop distribution in the considered area. The second part describes the chemical equilibrium process between the heavy metal and the soil, assuming local equilibrium conditions within the compartments. A good agreement was obtained between the lab scale experimental assays and the model predictions. The model has also been used to examine the effect of the electrolyte neutralization within the scope of the acid-enhanced electrokinetic method. These simulations have foreseen problems related with the system evolution, which would not arise under one-dimensional geometries and are due to the changes of the potential distribution in the two-dimensional arrangement where some kind of short circuit arises, ultimately leading to a decrease of the system efficiency.     

Oxidative degradation of 2,4-xylidine by photosensitization with 2,4,6-triphenylpyrylium: homogeneous and heterogeneous catalysis

The possibility of using zeolites containing the 2,4,6-triphenylpyrylium cation as photocatalysts for the degradation of pollutants has been tested on aqueous xylidine (2,4-dimethylaniline) solutions as models for contaminated wastewaters. The influence of the photocatalyst and substrate concentrations on xylidine oxidation has been investigated in homogeneous solution, by performing a series of experiments chosen according to the experimental design methodology (Doehlert uniform array). The empirical models and the corresponding response surfaces obtained from data analysis have been used for simulating and predicting degradation efficiency. The results have shown that conversion increases with increasing amounts of photocatalyst and decreasing concentration of the model pollutant. The fluorescence of 2,4,6-triphenylpyrylium was quenched by xylidine with a rate constant k(q) of 3.1x10(9)M(-1)s(-1). This result suggests a direct electron transfer between the excited pyrylium salt and xylidine. Because of the limited stability of the photocatalyst in homogeneous media, a pyrylium containing Y-zeolite has been tested for the photocatalytic oxidation of xylidine under heterogeneous conditions. The results suggest that the supported catalyst has a much improved stability and that xylidine oxidation rates remain nearly constant during the whole reaction time. An additional advantage of the pyrylium containing zeolite photocatalyst is that it can be recycled and used for further experiments.     

Linkage of a geographical information system with the gleams model to assess nitrate leaching in agricultural areas

The GLEAMS (Groundwater Loading Effects of Agricultural Management Systems, Version 2.10) model was linked with a Geographical Information System (GIS) to evaluate the risk of nitrate pollution in an area of 230 km2 near Valencia (Spain). Under Mediterranean conditions, GLEAMS was calibrated and validated using results from field experiments on citrus orchards and vegetables grown in that area. A graphical user interface (GUI) was implemented in the GIS-model system to allow a non-specialist to run the model, and to represent simulation results as a thematic map. In order to execute the GLEAMS model, data must be grouped in five basic layers: four layers correspond to the base maps (soils, climate, land use, NO3 content in irrigation water), and the fifth layer corresponds to agricultural management practices, introduced in the system interacting to the GUI. To illustrate system capabilities. two rotations with crops in the vegetable area (potato/lettuce/onion/cauliflower, and artichoke/artichoke in 2 years rotation each), and orange trees in the citrus area, were simulated to determine the N leached in the study area. Pollution risk maps show that vegetable crops and areas irrigated with groundwater have the highest potential risk of groundwater nitrate pollution. Further analysis identified potato and artichoke (in the first year) to be the crops with the higher risk.     

Anguilla anguilla L. oxidative stress biomarkers responses to copper exposure with or without beta-naphthoflavone pre-exposure

The redox cycling of heavy metals as well as their interactions with organic pollutants is a major contributor to the oxidative stress resulting from aquatic pollution. Therefore, in order to evaluate beta-naphthoflavone (BNF), Cu and BNF/Cu-induced oxidative stress with single and subsequent exposures, research was carried out in European eel (Anguilla anguilla L.). Eel gill and kidney oxidative stress biomarker responses such as lipid peroxidation (LPO), glutathione peroxidase (GPX), catalase (CAT), glutathione S-transferase (GST) and total reduced glutathione (GSH) to a single 24 h exposure to two copper concentrations (Cu-1 microM, 2.5 microM) and BNF (2.7 microM) with or without 24 h BNF (2.7 microM) pre-exposure were investigated. Cu exposure alone showed a significant gill GST increase at the lowest concentration and GSH content decrease for the highest concentration. Double BNF exposure in gill demonstrated a significant increase in LPO, CAT, GPX and GST, as well as a decrease in GSH content. However, in sequential BNF/Cu exposures, only the highest Cu concentration exhibited a significant increase in LPO and GSH as well as a decrease in GPX (vs. BNF + CW). In kidney, Cu exposure alone showed a significant CAT and GSH contents decrease for both concentrations, and at highest concentration in GPX; as well as GST increase at the lowest concentration. Double BNF exposure showed a significant increase in LPO and GST. Nevertheless, in sequential BNF/Cu exposures, both concentrations exhibited a significant increase in LPO and decrease in GSH contents. Moreover, LPO was also increased significantly in comparison to BNF+CW and the equivalent Cu exposures without BNF pre-exposure. Concerning GPX, a significant increase was observed at highest Cu concentration. In GST, a significant decrease at the lowest Cu concentration and increase at the highest Cu concentration was observed. Summarizing, a simple copper or BNF exposures have no ability to induce LPO in both gill and kidney. However, double BNF exposure induced LPO in both organs and sequential BNF/Cu exposures potentiated the risk of peroxidative damage occurrence in both organs. BNF/Cu interference on antioxidant responses differs between the studied organs. In gill, antagonistic effects were denoted with probable reflex in terms of peroxidative damage increase. In kidney, BNF pre-exposure prevented CAT and GPX inhibition by copper; though, no advantage of this effect was perceptible as defence against LPO generation. Considering BNF as a surrogate for a PAH and the detected interactions with copper, as well as the likelihood that these effects would be observed in polluted ecosystems, current results demonstrate their relevance to actual ecological exposures contributing to a better knowledge on oxidative stress mechanisms in fish.     

Sperm competition and evidence of sperm fertilization patterns in the carrion ball-roller beetle Canthon cyanellus cyanellus LeConte (Scarabaeidae: Scarabaeinae)

Field observation and laboratory experiments were conducted to investigate sperm competition and patterns of sperm fertilization under different experimental conditions in the carrion ball-roller beetle Canthon cyanellus cyanellus. Males in nature can mate with females whose spermathecae contains fertile sperm from other males. Sperm precedence was investigated using a visible genetic marker. The progeny of red (homozygous recessive) virgin females mated once with a red male and afterward, once with a green beetle (homozygous dominant) and vice versa, revealed that regardless of its color, the last male to mate fertilized c.a. 50% of the eggs, suggesting strong sperm competition. Males were able to achieve higher levels of paternity (more than 80%) when mated ad libitum with previously mated females, although large amount of variance in paternity does not exclude the possibility of first male sperm precedence or female cryptic choice. These results suggest that repeated mating and sperm replacement are the mechanisms by which last males achieve sperm precedence.