Characterisation of PM10 emissions from woodstove combustion of common woods grown in Portugal

A series of source tests was performed to evaluate the chemical composition of particle emissions from the woodstove combustion of four prevalent Portuguese species of woods: Pinus pinaster (maritime pine), Eucalyptus globulus (eucalyptus), Quercus suber (cork oak) and Acacia longifolia (golden wattle). Analyses included water-soluble ions, metals, radionuclides, organic and elemental carbon (OC and EC), humic-like substances (HULIS), cellulose and approximately l80 organic compounds. Particle (PM₁₀) emission factors from eucalyptus and oak were higher than those from pine and acacia. The carbonaceous matter represented 44–63% of the particulate mass emitted during the combustion process, regardless of species burned. The major organic components of smoke particles, for all the wood species studied, with the exception of the golden wattle (0.07–1.9% w/w), were anhydrosugars (0.2–17% w/w). Conflicting with what was expected, only small amounts of cellulose were found in wood smoke. As for HULIS, average particle mass concentrations ranged from 1.5% to 3.0%. The golden wattle wood smoke presented much higher concentrations of ions and metal species than the emissions from the other wood types. The results of the analysis of radionuclides revealed that the ²²⁶Ra was the naturally occurring radionuclide more enriched in PM₁₀. The chromatographically resolved organics included n-alkanes, n-alkenes, PAH, oxygenated PAH, n-alkanals, ketones, n-alkanols, terpenoids, triterpenoids, phenolic compounds, phytosterols, alcohols, n-alkanoic acids, n-di-acids, unsaturated acids and alkyl ester acids.     

Characterisation of particulate exposure during fireworks displays

Little is known about the level and content of exposure to fine particles (PM_2.5) among persons who attend fireworks displays and those who live nearby. An evaluation of the levels of PM_2.5 and their elemental content was carried out during the nine launches of the 2007 Montréal International Fireworks Competition. For each event, a prediction of the location of the firework plume was obtained from the Canadian Meteorological Centre (CMC) of the Meteorological Service of Canada. PM_2.5 was measured continuously with a photometer (Sidepak?, TSI) within the predicted plume location (“predicted sites”), and integrated samples were collected using portable personal samplers. An additional sampler was located on a nearby roof (“fixed site”). The elemental composition of the collected PM_2.5 samples from the “predicted sites” was determined using both a non-destructive energy dispersive ED-XRF method and an ICP-MS method with a near-total microwave-assisted acid digestion. The elemental composition of the “fixed site” samples was determined by the ICP-MS with the near-total digestion method. The highest PM_2.5 levels reached nearly 10 000 μg m^?3, roughly 1000 times background levels. Elements such as K, Cl, Al, Mg and Ti were markedly higher in plume-exposed filters. This study shows that 1) persons in the plume and in close proximity to the launch site may be exposed to extremely high levels of PM_2.5 for the duration of the display and, 2) that the plume contains specific elements for which little is known of their acute cardio-respiratory toxicity.     

Variation of raw wastewater microbiological quality in dry and wet weather conditions

The microbiological quality of urban wastewaters presents important environmental, sanitary, and political challenges. However, the variability of untreated wastewater quality is seldom known when it comes to microbial parameters. This study aims to evaluate the variability of microbiological quality in wastewater influents from different wastewater treatment plants connected to combined and partially separate sewer networks in the Parisian area and to evaluate the impact of this variability on the treatment efficiency and on the accuracy of wastewater effluent monitoring. The densities of fecal indicator bacteria (FIB), Escherichia coli and intestinal enterococci, and their partitioning on settleable particles were analyzed at the inlet of two wastewater treatment plants during dry weather (130 composite samples and 7 days sampled every 2 hours) and storm events (39 composite samples, and 7 rain courses) from 2008 to 2012. The results showed that fecal indicator densities vary according to the network characteristics and according to the meteorological conditions. During storm events, a significant dilution of E. coli and enterococci was observed, as well as a decrease in the settleable fraction of E. coli during the maximal impact of the storm. However, storm events did not significantly impact the regular FIB monitoring. FIB removals by primary and secondary treatment were significantly correlated with FIB densities in influent wastewater; however, meteorological conditions also influenced the removal of FIB.     

A hybrid micro-scale model for transport in connected macro-pores in porous media

This paper presents a hybrid model for transport in connected macro-pores in porous media. A pore-scale model is used to parameterize the hybrid model. The hybrid model explicitly models the advection and diffusion of species in the connected macro-pores and treats the porous media around the connected macro-pores as a continuum with effective transport properties. The pore-scale model is used to calculate the effective transport properties of the porous continuum. This approach negates the need to calibrate the hybrid model against experimental data, which is common for continuum-scale models of porous media, and allows an arbitrary microstructure to be considered. The paper presents the multi-scale modeling approach along with the details of the hybrid and pore-scale models. Validation of the model is also presented along with several case studies investigating the applicability of the multi-scale modeling approach to different geometries and transport conditions. The case studies show that the multi-scale modeling approach is accurate for various connected macro-pore geometries given that the porosity of the porous medium around the connected macro-pores is sufficiently small. The accuracy of the hybrid model decreases with increasing porosity of the matrix.     

Wood burning impact on PM10 in three Austrian regions

Anhydrosugars (levoglucosan, mannosan and galactosan) were investigated during one year in three Austrian regions at three types of sites (city-heavy traffic-impacted, city-residential and background) in order to assess the magnitude of the contribution of wood smoke to the particulate matter load and its organic fraction. The annually averaged concentrations of levoglucosan ranged from 0.12 to 0.48 μg m^?3. The levoglucosan concentration exhibited a strong annual cycle with higher concentrations in the cold season. The minor anhydrosugars had a similar annual trend, but their concentrations were lower by a factor of about 5 and about 25 in the cold season for mannosan and galactosan, respectively. Levoglucosan concentrations were higher at the inner-urban as compared to rural sites. The contribution of wood smoke to organic carbon and PM₁₀ levels was calculated using a constant ratio of levoglucosan and OC, respectively PM₁₀ as derived for fire wood typical for Alpine European regions [Schmidl, C., Marr, I.L., Caseiro, A.e, Kotianová, P., Berner, A., Bauer, H., Kasper-Giebl, A., Puxbaum, H., 2008a. Chemical characterisation of fine particle emissions from wood stove combustion of common woods growing in mid-European Alpine regions. Atmospheric Environment 42, 126–141]. The estimated contribution of wood smoke-OC to the OC of PM₁₀ ranged from one third to more than half in the cold season with higher contributions up to 70% in winter (December, January and February) in the smaller cities and the rural background. This indicates, that wood smoke is the predominant source of organic material at rural and small urban sites in central Europe. Consistently, wood smoke was an important contributor to PM₁₀ during the cold season, with contributions of around 10% in the Vienna larger region and around 20% at rural sites in the densely forested regions of Salzburg and Styria during the winter months. In those regions residential sites exhibited highest relative wood smoke contents in PM₁₀ during autumn (September till November), indicating the use of wood stoves for auxiliary heating in the transition of warm to cold season. Using the relationships between the different anhydrosugars the combustion of softwood was found to be dominant for the wood smoke occurrence in ambient air at the investigated sites. Potassium, a commonly used tracer for biomass burning, correlated well to levoglucosan, with a mass ratio of around 0.80 in the cold season.     

Aerosol formation yields from the reaction of catechol with ozone

The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers. Aerosol production was monitored using a scanning mobility particle sizer and loss of the precursor was determined by gas chromatography and infrared spectroscopy, whilst ozone concentrations were measured using a UV photometric analyzer. The overall organic aerosol yield (Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses (M_o) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm^?3. Analysis of the data clearly shows that Y is a strong function of M_o and that secondary organic aerosol formation can be expressed by a one-product gas–particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The results of this work are compared to similar studies reported in the literature.     

Mass conservative,positive definite integrator for atmospheric chemical dynamics

Air quality models compute the transformation of species in the atmosphere undergoing chemical and physical changes. The numerical algorithms used to predict these transformations should obey mass conservation and positive definiteness properties. Among all physical phenomena, the chemical kinetics solver provides the greatest challenge to attain these two properties. In general, most chemical kinetics solvers are mass conservative but not positive definite. In this article, a new numerical algorithm for the computation of chemical kinetics is presented. The integrator is called Split Single Reaction Integrator (SSRI). It is both mass conservative and positive definite. It solves each chemical reaction exactly and uses operator splitting techniques (symmetric split) to combine them into the entire system.The method can be used within a host integrator to fix the negative concentrations while preserving the mass, or it can be used as a standalone integrator that guarantees positive definiteness and mass conservation. Numerical results show that the new integrator, used as a standalone integrator, is second order accurate and stable under large fixed time steps when other conventional integrators are unstable.     

Renewable energy and greenhouse gas emissions from the waste sectors of European Union member states: a panel data analysis

In the last two decades, there has been a rich debate about the environmental degradation that results from exposure to solid urban waste. Growing public concern with environmental issues has led to the implementation of various strategic plans for waste management in several developed countries, especially in the European Union. In this paper, the relationships were assessed between economic growth, renewable energy extraction and greenhouse gas (GHG) emissions in the waste sector. The Environmental Kuznets Curve hypothesis was analysed for the member states of the European Union, in the presence of electricity generation, landfill and GHG emissions for the period 1995 to 2012. The results revealed that there is no inverted-U-shaped relationship between income and GHG emissions in European Union countries. The renewable fuel extracted from waste contributes to a reduction in GHG, and although the electricity produced also increases emissions somewhat, they would be far greater if the waste-based generation of renewable energy did not take place. The waste sector needs to strengthen its political, economic, institutional and social communication instruments to meet its aims for mitigating the levels of pollutants generated by European economies. To achieve the objectives of the Horizon 2020 programme, currently in force in the countries of the European Union, it will be necessary to increase the share of renewable energy in the energy mix.     

Earthworm ecotoxicological assessments of pesticides used to treat seeds under tropical conditions

Ecotoxicological laboratory tests (lower-tier tests) are fundamental tools for assessing the toxicity of pesticides to soil organisms. In this study, using these tests under tropical conditions, we quantified the impact of the insecticides imidacloprid, fipronil, and thiametoxam, and the fungicides captan and carboxin + thiram, all of which are used in the chemical treatment of crop seeds, on the survival, reproduction, and behavior of Eisenia andrei (Oligochaeta). With the exception of imidacloprid, none of the pesticides tested caused mortality in E. andrei in artificial soils. The LC₅₀ of imidacloprid was estimated as 25.53 mg active ingredient kg^?1 of dry soil. Earthworm reproduction rates were reduced by imidacloprid (EC₅₀ = 4.07 mg kg^?1), fipronil (EC₂₀ = 23.16 mg kg^?1), carboxin + thiram (EC₅₀ = 56.38 mg kg^?1), captan (EC₅₀ = 334.84 mg kg^?1), and thiametoxam (EC₅₀ = 791.99 mg kg^?1). Avoidance behavior was observed in the presence of imidacloprid (AC₅₀ = 0.11 mg kg^?1), captan (AC₅₀ = 33.54 mg kg^?1), carboxin + thiram (AC₅₀ = 60.32 mg kg^?1), and thiametoxam (AC₅₀ = >20 mg kg^?1). Earthworms showed a preference for soils with the insecticide fipronil. Imidacloprid was the most toxic of the substances tested for E. andrei. The avoidance test was the most sensitive test for most pesticides studied, but results varied between pesticides. These results offer new insights on the toxicity of pesticides used to treat seeds in tropical regions. However, they should be complemented with higher-tier tests in order to reduce the uncertainties in risk assessment.     

Developmental exposure to diuron causes splenotoxicity in male Sprague-Dawley rat pups

This study investigated whether perinatal exposure to diuron [3-(3,4-dichlorophenyl)-1-1-dimethylurea] might exert adverse effects on rat lymphoid organs. Pregnant Sprague-Dawley (SD) rats were exposed to diuron at 500, 750 or 1250 ppm in the diet from gestational days (GD) 12-21 and during lactation. At postnatal day (PND) 42, male pups were euthanized and thymus, spleen, mesenteric lymph node and femur were collected for histopathological analysis. Food consumption and body weight gain were significantly reduced in dams exposed to 1250 ppm during gestation period. Also, Diuron at 750 and 1250 ppm produced: (1) increased relative spleen weight associated histologically with severe congestion in red pulp, (2) enhanced extramedullary hematopoiesis and hemosiderosis as well as (3) depletion of lymphoid follicles in white pulp. Flow cytometric analysis revealed a significant reduction in B lymphocytes (CD45RA+) in male pups but T lymphocytes (CD4+, CD8+ and CD4+/CD8+) were not markedly affected. Thus, data suggest that Diuron-induced maternal toxicity in dams exposed to high dose and perinatal exposure to this herbicide produced spleen toxicity as evidenced by a reduction in B lymphocyte number in male SD pups.