A spatial multicriteria model for determining air pollution at sample locations

Atmospheric pollution in urban centers has been one of the main causes of human illness related to the respiratory and circulatory system. Efficient monitoring of air quality is a source of information for environmental management and public health. This study investigates the spatial patterns of atmospheric pollution using a spatial multicriteria model that helps target locations for air pollution monitoring sites. The main objective was to identify high-priority areas for measuring human exposures to air pollutants as they relate to emission sources. The method proved to be viable and flexible in its application to various areas.

Implications:?Spatial multicriteria models provide a tool for air pollution management in urban areas. Analytic hierarchy process (AHP) modeling can help with the process of prioritizing monitoring site locations and minimizing costs.     

Application of simulation models to the diagnosis of MSW landfills: an example

Among the landfill simulation programs being developed by several research groups around the world as tools for the management of sanitary landfills is MODUELO, whose second version, MODUELO 2, has been presented elsewhere. It reproduces the operational history of the landfill and its hydrologic and biodegradation processes, allowing the estimation of the flow and pollutants emitted in the leachate and the generated landfill gas over time. This program has been used for a diagnosis study of an existing European MSW landfill. The construction and calibration of the facility's hydrologic model, based on the available data, allowed the detection and quantification of two sources increasing the flows reaching the leachate collection system: a small portion (6-7%) of the runoff over the landfill surface and the contribution of water coming from external hillsides of the same watershed that represent a total surface area of around 20ha. The contrast of the leachate quality (COD, BOD, NH(4)-N and TKN) simulation results and measured data showed the potential of these models for the assessment of other significant aspects in landfill operation such as the potential harnessing of the landfill gas. Nonetheless, in this case as in many others, the accuracy of the simulation results was limited by the scant quality of the available data, which highlights the need for implementing continuous monitoring and characterizing protocols to take advantage of these programs as a tool for landfill optimization.     

Clay charge reversal effects on aqueous polymer sorption on lateritic soils

The effects of charge reversal about the measured point of zero charge (pH(0) approximately 5.2) of untreated and treated Sete Lagoas lateritic soil of Brazil on aqueous polymer sorption was investigated. The polymers are anionic sodium carboxymethyl cellulose (CMCA), nonionic polyethylene oxide (PEO), and cationic polyacrylamide (PAM). They were prepared at aqueous concentrations and pH ranges of 0.1-2.0 g l(-1) and 2-9, respectively. Soil treatment involved the removal of iron oxides by treatment with dithionate-bicarbonate-citrate. Batch sorption test results show that the presence of iron oxides in lateritic soil tends to suppress sorption of CMCA (especially at pH=pH(0)) and PEO (for the whole pH range) but has uncertain effects on cationic PAM sorption. CMCA sorption on the untreated soil improves on either side of pH(0), in direct proportionality to solution concentration, except at pH<4.0, where disassociation of the polymer molecules may decrease sorption energy. Increase in the sorption of non-cationic polymers (CMCA and PEO) at pH>pH(0) is attributable to dispersion of clay, cation bridging and polymer molecular reconfiguration. For cationic PAM, electrostatic bonding to negatively charged soil particle surfaces accounts for the sorption increase. For treated soil samples, polymer sorption pattern is similar to those expected for the montmorillonitic clayey soils of temperate zones. These results indicate that the pH(0) of lateritic soils, within the regime that exists in the field, should be considered in assessing the potential effectiveness of polymer dust suppressants for tropical lateritic soils.     

Ozonation of aniline promoted by activated carbon

The removal of aniline from aqueous solutions by simultaneous use of ozone and activated carbon was investigated at different solution pH. For comparative purposes, single ozonation and adsorption on activated carbon were carried out in the same experimental set-up. In order to evaluate the role of the activated carbon surface chemistry during ozonation, a commercial activated carbon, Norit GAC 1240 PLUS, was submitted to oxidation in the liquid phase with HNO(3). The texture and surface chemistry of the activated carbon samples were characterized. During ozonation, complete conversion of aniline was achieved after approximately 20 min, regardless of the presence of activated carbon. In all cases, several by-products were formed during ozonation. Nitrobenzene, o- and p-aminophenol were the primary aromatic oxidation by-products identified. In terms of TOC removal, best results were achieved by the simultaneous use of ozone and activated carbon. Though there is a strong contribution of adsorption, a considerable synergetic effect between ozone and activated carbon is observed. In general, activated carbon promotes the reaction of ozonation enhancing the efficiency of this treatment process. The basic activated carbon presented greater activity in this process leading to higher mineralization rates.     

Modification of the degradative capacity of a soil artificially contaminated with diesel

Samples of an Ah horizon from a Cambisol under oakwood vegetation were artificially contaminated with diesel (at doses of 20, 40, 80, 160 and 400 microl g(-1)) under laboratory conditions. The presence of the contaminant caused a decrease in the microbial biomass and in phosphomonoesterase, beta-glucosidase and particularly, urease activities. In contrast, the basal respiration and mineralization of nitrogen, specifically ammonification, both increased. The microorganisms that survived in the contaminated soil showed increased metabolic activity, as a result of their use of dead microorganisms as a substrate and of a lack of competition. Although the results indicate that the properties related to the degradative capacity of the soils varied differently in response to the contamination, the use of a biochemical quality index (including different biochemical properties), which was designed for estimating the degree of deterioration of the soil, revealed a clear decrease in the biochemical quality of the diesel-contaminated soils.     

Influence of ozone pre-treatment on sludge anaerobic digestion: removal of pharmaceutical and personal care products

The effect of an oxidative pre-treatment with ozone on the removal of Pharmaceutical and Personal Care Products (PPCPs) during the anaerobic digestion of sewage sludge has been investigated. Besides, the digested sludge characteristics in terms of pathogens content, dewatering properties, heavy metals content and linear alkylbenzene sulfonates (LAS) were determined. During ozonation (20mg O(3)/g TSS), about 8% of volatile solids (VS) and 60% of the chemical oxygen demand (COD) were solubilized. However, no mineralization was observed. The elimination of VS and total COD during anaerobic digestion were not affected by ozone treatment with efficiencies ranging from 60% to 65%. All PPCPs considered were removed during anaerobic treatment of sludge, with efficiencies ranging from 20% to 99%. No significant influence of ozone pre-treatment was observed on PPCPs elimination except for carbamazepine. Pathogens, heavy metals and LAS contents after conventional and pre-ozonation treatment of sewage sludge were below the legal requirements. However, the dewatering properties of sludge were deteriorated when the ozone pre-treatment was applied.     

Total and partial digestion of sediments for the evaluation of trace element environmental pollution

Four different sample treatment methods for the determination of trace elements have been compared: a total digestion with HNO3-H2O2-HF using microwave, and three different standardized methods of fractionation: BCR three-steps sequential extraction, USEPA standard 3050B and ISO standard 11466. The four treatment methods were applied to the determination of Cu and Ni in four samples collected in different areas of Cienfuegos Bay (Cuba). The location of samples and the analytes were selected on the basis of results obtained by previous studies. Analyses following total digestion and BCR three-steps procedure were performed by inductively coupled plasma mass spectroscopy whereas analyses following EPA and ISO procedures were performed by flame atomic absorption spectroscopy. The results obtained have been compared with an estimated anthropic fraction evaluated in each sampling point as the difference between the total concentration and an estimated background concentration level. The BCR three-steps provided the best approximation of the estimated anthropic fraction and was therefore applied also in the determination of Pb and Cd for further consideration.     

Water deficit stress induces different monoterpene and sesquiterpene emission changes in Mediterranean species. Relationship between terpene emissions and plant water potential

The effects of water deficit stress and plant water potential (psi) on monoterpene and sesquiterpene leaf emissions from Rosmarinus officinalis, Pinus halepensis, Cistus albidus and Quercus coccifera were studied over 11 days of water withholding (from t(1) to t(11)), after substrates had achieved their field capacity (control pots: t(0)). Volatile compounds were sampled from the same twig per plant all throughout the study, using a dynamic bag enclosure system. Volatiles, collected in Tenax TA, were studied by means of GC-FID and GC-MS. Monoterpene emissions of water stressed plants (t(1)-t(11)) were either similar to those of control seedlings (R. officinalis and Q. coccifera) or higher (P. halepensis and C. albidus). By contrast, sesquiterpene emissions were strongly reduced or inhibited after four days of water withholding, particularly for R. officinalis, thus altering terpene emission composition. Despite the positive effect of water stress on leaf monoterpene emissions of P. halepensis and C. albidus, the significant correlation between these emissions and psi showed a slow decrease of these emissions over long term water deficit periods. This contrasted with the rapid decline of sesquiterpene emissions of R. officinalis according to lower values of psi. These results provide an overall picture of the different responses of monoterpene and sesquiterpene emissions to progressive water loss. They also reveal the utility of using psi for estimating some emission rates of some species according to drought conditions.     

A rapid, sensitive screening test for polycyclic aromatic hydrocarbons applied to Antarctic water

We describe a rapid, sensitive, fluorescence screening test for polycyclic aromatic hydrocarbons in water samples that avoids more costly time-consuming methods. The screening test works by detecting benzo[a]pyrene. It runs without the need for any pre-concentration step, thus rendering it suitable for routine use in water-quality-control laboratories. The test recognizes contaminated samples rapidly (150 s) and inexpensively with a cut-off level of 10 ng l(-1), which is the value that the European Union and World Health Organization (WHO) have laid down in its assessment of the quality of water for human consumption. This was first ascertained by analysing tap and waste-water samples before studying environmental water samples from the Antarctic region. The reliability of the screening test was 2% false positives and 4% false negatives in 200 samples of tap and waste-water. The applicability was confirmed by the fact that the predictions of the screening test coincided exactly with results obtained with gas chromatography-mass spectrometry assays. We also discuss the polluted Antarctic samples and the possible sources of the contamination involved.     

Degradation of the herbicide 2,4-DP by anodic oxidation, electro-Fenton and photoelectro-Fenton using platinum and boron-doped diamond anodes

This paper reports the degradation of 2,4-DP (2-(2,4-dichlorophenoxy)-propionic acid) solutions of pH 3.0 by environmentally friendly electrochemical methods such as anodic oxidation, electro-Fenton and photoelectro-Fenton with a Pt or boron-doped diamond (BDD) anode. In the two latter techniques an O(2)-diffusion cathode was used and 1.0mM Fe(2+) was added to the solution to give hydroxyl radical (*OH) from Fenton's reaction between Fe(2+) and H(2)O(2) generated at the cathode. All treatments with BDD are viable to decontaminate acidic wastewaters containing 2,4-DP since they give complete mineralization, with loss of chloride ion, at high current due to the great production of oxidant *OH at the BDD surface favoring the destruction of final carboxylic acids. *OH formed from Fenton's reaction destroys more rapidly aromatic products, making the electro-Fenton and photoelectro-Fenton processes much more efficient than anodic oxidation. UVA light in photoelectro-Fenton with BDD has little effect on the degradation rate of pollutants. The comparative procedures with Pt lead to slower decontamination because of the lower oxidizing power of this anode. The effect of current on the degradation rate and efficiency of all methods is studied. The 2,4-DP decay always follows a pseudo-first-order kinetics. Chlorohydroquinone, chloro-p-benzoquinone and maleic, fumaric, malic, lactic, pyruvic, acetic, formic and oxalic acids are detected as products by chromatographic techniques. A general sequence accounting for by the reaction of all these intermediates with the different oxidizing agents is proposed.