The importance of the location of sodium chlorite application in a multipollutant flue gas cleaning system

In this study, removing sulfur dioxide (SO2), nitrogen oxides (NO(x)), and mercury (Hg) from simulated flue gas was investigated in two laboratory-sized bubbling reactors that simulated an oxidizing reactor (where the NO and Hg(0) oxidation reactions are expected to occur) and a wet limestone scrubber, respectively. A sodium chlorite solution was used as the oxidizing agent. The sodium chlorite solution was an effective additive that enhanced the NO(x), Hg, and SO2 capture from the flue gas. Furthermore, it was discovered that the location of the sodium chlorite application (before, in, or after the wet scrubber) greatly influences which pollutants are removed and the amount removed. This effect is related to the chemical conditions (pH, absence/presence of particular gases) that are present at different positions throughout the flue gas cleaning system profile. The research results indicated that there is a potential to achieve nearly zero SO2, NO(x), and Hg emissions (complete SO2, NO, and Hg removals and -90% of NO(x) absorption from initial values of 1500 ppmv of SO2, 200 ppmv of NO(x), and 206 microg/m3 of Hg(0)) from the flue gas when sodium chlorite was applied before the wet limestone scrubber. However applying the oxidizer after the wet limestone scrubber was the most effective configuration for Hg and NO(x) control for extremely low chlorite concentrations (below 0.002 M) and therefore appears to be the best configuration for Hg control or as an additional step in NO(x) recleaning (after other NO(x) control facilities). The multipollutant scrubber, into which the chlorite was injected simultaneously with the calcium carbonate slurry, appeared to be the least expensive solution (when consider only capital cost), but exhibited the lowest NO(x) absorption at -50%. The bench-scale test results presented can be used to develop performance predictions for a full- or pilot-scale multipollutant flue gas cleaning system equipped with wet flue gas desulfurization scrubber.     

Fate of PBDEs during food processing: Assessment of formation of mixed chlorinated/brominated diphenyl ethers and brominated dioxins/furans

The aim of this study was to evaluate effects of food processing on PBDE levels, in particular influence of heat treatment on degradation of PBDEs, including possible formation of chlorinated diphenyl ethers or brominated dioxins/furans as degradation products. It was shown that PBDEs heated in the presence of chlorine (from either organic or inorganic sources) formed mixed chlorinated/brominated diphenyl ethers. However, no PCDEs were formed in the presence of lipids. Lipid medium increased stability of PBDEs exposed to UV irradiation. Profile of congeners formed in result of the debromination reaction was significantly different than profiles observed by some other authors in aliphatic organic solvents. Grilling processes increased concentrations (calculated on the fresh product basis) of the studied compounds by 4–8/22–34% for electric/coal grill, respectively. Depending on the congener and on the applied heat treatment, PBDE mass in pork meat after grilling dropped by 26–53%. No detectable quantities of either brominated dioxins or furans were formed during thermal processing of food containing typical levels of PBDEs.     

Trace level determination of selected sulfonylurea herbicides in wetland sediment by liquid chromatography electrospray tandem mass spectrometry

Sulfonylurea herbicides are widely used in crop production on the Canadian prairies and a portion of these herbicides applied to cropland are inevitably lost to surrounding aquatic ecosystems. Little is known regarding the presence of sulfonylurea herbicides in wetlands located amongst cropland. This paper describes a new analytical method for the extraction and the determination of seven sulfonylurea herbicides (thifensulfuron-methyl, tribenuron-methyl, ethametsulfuron-methyl, metsulfuron-methyl, rimsulfuron, nicosulfuron and sulfosulfuron) in wetland sediment. The method provided > 85% analyte recovery from fortified sediment for six of the seven sulfonylurea herbicides with a limit of quantification (LOQ) of 1.0 μ g kg^{? 1}. Tribenuron-methyl had significantly lower recovery compared to the other six sulfonylurea herbicides (LOQ = 2 μ g kg^{? 1}). Mean recovery standard deviations were < 10%. This methodology was used to quantify sulfonylurea herbicide residues in sediment samples collected from prairie wetlands situated within the agricultural landscape of Saskatchewan and Manitoba, Canada. This is the first-known detection of sulfonylurea herbicide residues in prairie wetland sediments. Ethametsulfuron-methyl, sulfosulfuron and metsulfuron-methyl, the three most environmentally persistent of the seven sulfonylurea herbicides monitored in the surveillance component of this study, were most frequently detected in wetland sediment with mean concentrations ranging from 1.2 to 10 μ g kg^{? 1}.     

Evaluation of Human Exposure to Ambient PM10 in the Metropolitan Area of Mexico City Using a GIS-Based Methodology

ABSTRACT

The main goal of this study was to evaluate the magnitude of outdoor exposure to fine particulate matter (PM₁₀) potentially experienced by the population of metropolitan Mexico City. With the use of a geographic information system (GIS), spatially resolved PM₁₀ distributions were generated and linked to the local population. The PM₁₀ concentration exceeded the 24-hr air quality standard of 150 μg/m³ on 16% of the days, and the annual air quality standard of 50 μg/m³ was exceeded by almost twice its value in some places. The basic methodology described in this paper integrates spatial demographic and air quality databases, allowing the evaluation of various air pollution reduction scenarios. Achieving the annual air quality standard would represent a reduction in the annual arithmetic average concentration of 14 μg/m³ for the typical inhabitant. Human exposure to particulate matter (PM) has been associated with mortality and morbidity in Mexico City; reducing the concentration levels of this pollutant would represent a reduction in mortality and morbidity and the associated cost of such impacts. This methodology is critical to assessing the potential benefits of the current initiative to improve air quality implemented by the Environmental Metropolitan Commission of Mexico City.     

Evaluation of the effects, on canopy arthropods, of two agricultural management systems to control pests in olive groves from north-east of Portugal

This study aims to investigate the effect of management regime on canopy arthropod community of the olive tree (Olea europaea L.). Field studies were performed in two successive years, 2002 and 2003, in two olive groves, one under organic farming and the other under integrated protection. The integrated protection grove was sprayed once a year in June, with dimethoate, to control the anthophagous generation of the olive moth, Prays oleae (Bern.). From April to November of each year, the canopy arthropods were sampled weekly. PRC method was used to analyse the effect of management regime at the community level and results showed that taxa responded differently to insecticide application suggesting that the organic grove was a more suitable habitat for the arthropods than the integrated protection grove. Abundance of arthropods peaked in May and June for both years but, after spraying with dimethoate, decreased significantly in integrated protection grove, recovering very slowly thereafter. Psocoptera, Miridae, Formicidae and Coccinellidae were the most sensitive taxa to insecticide application. Their decreasing in abundance was more evident in the second year of the trial. On the other hand chrysopids showed some tolerance to insecticide applications. These results suggest that the timing of spray is of utmost importance in reducing the side effects of spraying on beneficial arthropods. Moreover, differences in population susceptibility as well as in life cycle patterns must be considered.     

Characterization of Atrazine-Loaded Biodegradable Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Microspheres

Polyhydroxybutyrate-co-hydroxyvalerate microspheres (PHBV-MS) were prepared as a delivery system for the herbicide atrazine (ATZ). Characterization of the system included investigation of in vitro release properties and genotoxicity. ATZ − PHBV-MS particle diameters showed a size distribution range of 1–13 μm. Differential scanning calorimetry analyses indicated that ATZ was associated with the PHBV microparticles. The release profiles showed a different release behavior for the pure herbicide in solution, as compared with that containing ATZ-loaded PHBV-MS. Korsmeyer–Peppas model analyses showed that atrazine release from the microparticles occurred by a combination of diffusion through the matrix and partial diffusion through water-filled pores of the PHBV microparticles. A Lactuca sativa test result showed that the genotoxicity of ATZ-loaded PHBV-MP was decreased in relation to ATZ alone. The results demonstrate a viable biodegradable herbicide release system using atrazine for agrochemical purposes.     

Shared ways of thinking in Brazil about the science–practice interface in ecology and conservation

The debate in the literature on the science–practice interface suggests a diversity of opinions on how to link science and practice to improve conservation. Understanding this diversity is key to addressing unequal power relations, avoiding the consideration of only dominant views, and identifying strategies to link science and practice. In turn, linking science and practice should promote conservation decisions that are socially robust and scientifically informed. To identify and describe the viewpoints of scientists and decision makers on how the science–practice interface should work in order to improve conservation decisions, we interviewed Brazilian scientists (ecologists and conservation scientists, n = 11) and decision makers (n = 11). We used Q methodology and asked participants to rank their agreement with 48 statements on how the science–practice interface should work in order to improve conservation decisions. We used principal component analysis to identify shared viewpoints. The predominant viewpoint, shared by scientists and decision makers, was characterized by valuing the integration of scientific and strategic knowledge to address environmental problems. The second viewpoint, held mostly by decision makers, was distinguished by assigning great importance to science in the decision-making process and calling for problem-relevant research. The third viewpoint, shared only by scientists, was characterized by an unwillingness to collaborate and a perception of scientists as producers of knowledge that may help decision makers. Most participants agreed organizations should promote collaboration and that actors and knowledge from both science and practice are relevant. Disagreements concerned specific roles assigned to actors, willingness to collaborate, and organizational and institutional arrangements considered effective to link science and practice. Our results suggest there is ample room for collaborations and that impediments lie mainly in existing organizations and formal institutional arrangements rather than in negative attitudes between scientists and decision makers.     

Is Indonesian peatland loss a cautionary tale for Peru? A two-country comparison of the magnitude and causes of tropical peatland degradation

Mitigation and Adaptation Strategies for Global Change - Indonesia and Peru harbor some of the largest lowland tropical peatland areas. Indonesian peatlands are subject to much greater...     

How wrong can you be? Implications of incorrect utility function specification for welfare measurement in choice experiments

Despite the vital role of the utility function in welfare measurement, the implications of working with incorrect utility specifications have been largely neglected in the choice experiments literature. This paper addresses the importance of specification with a special emphasis on the effects of mistaken assumptions about the marginal utility of income. Monte Carlo experiments were conducted using different functional forms of utility to generate simulated choices. Multi-Nomial Logit and Mixed Logit models were then estimated on these choices under correct and incorrect assumptions about the true, underlying utility function. Estimated willingness to pay measures from these choice modeling results are then compared with the equivalent measures directly calculated from the true utility specifications. Results show that for the parameter values and functional forms considered, a continuous-quadratic or a discrete-linear attribute specification is a good option regardless of the true effects the attribute has on utility. We also find that mistaken assumptions about preferences over costs magnify attribute mis-specification effects.