Analysis of C1, C2, and C10 through C33 particle-phase and semi-volatile organic compound emissions from heavy-duty diesel engines

To meet increasingly stringent regulations for diesel engines, technologies such as combustion strategies, aftertreatment components, and fuel composition have continually evolved. The emissions reduction achieved by individual aftertreatment components using the same engine and fuel has been assessed and published previously (Liu et al., 2008a, Liu et al., 2008b, Liu et al., 2008c). The present study instead adopted a systems approach to evaluate the net effect of the corresponding technologies for model-year 2004 and 2007 engines. The 2004 engine was equipped with an exhaust gas recirculation (EGR) system, while the 2007 engine had an EGR system, a crankcase emissions coalescer, and a diesel particulate filter. The test engines were operated under the transient federal test procedure and samples were collected with a source dilution sampling system designed to stimulate atmospheric cooling and dilution conditions. The samples were analyzed for elemental carbon, organic carbon, and C₁, C₂, and C₁₀ through C₃₃ particle-phase and semi-volatile organic compounds. Of the more than 150 organic species analyzed, the largest portion of the emissions from the 2004 engine consisted of formaldehyde, acetaldehyde, and naphthalene and its derivatives, which were significantly reduced by the 2007 engine and emissions technology. The systems approach in this study simulates the operation of real-world diesel engines, and may provide insight into the future development of integrated engine technology. The results supply updated information for assessing the impact of diesel engine emissions on the chemical processes, radiative properties, and toxic components of the atmosphere.     

Assessing PM10 source reduction in urban agglomerations for air quality compliance

The objective of this work was to study PM(10) and PM(2.5) concentration data available from monitoring stations in two large urban agglomerations in Greece and to estimate the emissions reduction required for compliance with the EU Air Quality Standards (AQS) for particulate matter. The cities studied are namely the Athens and Thessaloniki Metropolitan Areas (AMA and TMA, respectively). PM(10) concentrations during the period 2001-2010 have been evaluated for 15 air quality monitoring stations in the two urban areas. It was found that the concentrations of PM(10) during the period studied constantly exceeded the threshold values at the traffic and industrial stations in TMA and most of the traffic sites in AMA. Most of the occurrences of non-attainment to the daily AQSs were observed during the winter period at all stations (more pronounced for TMA stations). The reduction in current emission source strength to meet the air quality goal was calculated by the rollback equation using PM(10) day-averaged concentrations over the selected period at each station. Among the lognormal and Weibull distributions, the lognormal distribution was found to best fit the frequency distributions of PM(10) concentrations at the selected stations. The results showed that the minimum reduction required in order to meet the AQS in the AMA ranges from approximately 20 to 38% and up to 11% for traffic and background stations, respectively. Reductions in the range of 31% for traffic and 44% for industrial areas in TMA are also required. The same methodology was applied to PM(2.5) concentrations in the AMA and showed that emission reductions up to 31% are necessary in order to meet the 2020 EU AQS. Finally, continuous concentration data of organic (OC) and elementary carbon (EC) in PM(2.5) were used to study the possibility of achieving specific emission attenuation objectives in AMA.     

Relative sensitivity of two marine bivalves for detection of genotoxic and cytotoxic effects: a field assessment in the Tamar Estuary, South West England

The input of anthropogenic contaminants to the aquatic environment is a major concern for scientists, regulators and the public. This is especially relevant in areas such as the Tamar valley in SW England, which has a legacy of contamination from industrial activity in the nineteenth and twentieth centuries. Following on from previous laboratory validation studies, this study aimed to assess the relationship between genotoxic and cytotoxic responses and heavy metal concentrations in two bivalve species sampled from locations along the Tamar estuary. Adult cockles, Cerastoderma edule, and blue mussels, Mytilus edulis, were sampled from five locations in the Tamar and one reference location on the south Devon coast. Bivalve haemocytes were processed for comet and neutral red retention (NRR) assays to determine potential genotoxic and cytotoxic effects, respectively. Sediment and soft tissue samples were analysed for metal content by inductively coupled plasma mass spectrometry. Sediment concentrations were consistent with the physico-chemical nature of the Tamar estuary. A significant correlation (P?=?0.05) was found between total metal concentration in sediment and C. edule soft tissues, but no such correlation was found for M. edulis samples. DNA damage was elevated at the site with highest Cr concentrations for M. edulis and at the site with highest Ni and Pb concentrations for C. edule. Analysis of NRR revealed a slight increase in retention time at one site, in contrast to comet data. We conclude that the comet assay is a reliable indicator of genotoxic damage in the field for both M. edulis and C. edule and discuss reasons for the apparent discrepancy with NRR.     

Histopathology alterations and lipid peroxidation as biomarkers of hydrocarbon-induced stress in earthworm, Eudrilus eugeniae

This study investigated the biomarker responses of the earthworm, Eudrilus eugeniae, exposed to sublethal concentrations of benzene, toluene and xylene (BTX) for a time span of 28 days. Lipid peroxidation (LPO) and histopathological alterations were examined. Toxicological evaluations of BTX were carried out against E. eugeniae. On the basis of the 96-h LC₅₀ value, xylene (1.212 mg/kg) was found to be the most toxic followed by toluene (1.335 mg/kg) and benzene (1.896 mg/kg) was the least toxic. The exposure of earthworms to sublethal concentrations (1/10th and 1/100th of 96 h LC₅₀) of BTX premixed with the substrate (loamy and humus soil) induced pathological changes in the clitella such as severe lesion, necrosis and dark brown pigments. The result of the lipid peroxidation assay showed a significant increase in oxidative damage with LPO values ranging from 2.58–7.8 nM/g in exposed animals when compared to 0.07 nM/g in the control group. The findings from this study suggest the use of LPO and histopathology as useful biomarkers of exposure for early detection of petroleum related stress in terrestrial ecosystems     

Characterization of spatially homogeneous regions based on temporal patterns of fine particulate matter in the continental United States

Statistical analyses of time-series or spatial data have been widely used to investigate the behavior of ambient air pollutants. Because air pollution data are generally collected in a wide area of interest over a relatively long period, such analyses should take into account both spatial and temporal characteristics. The objective of this study is 2-fold: (1) to identify an efficient way to characterize the spatial variations of fine particulate matter (PM2.5) concentrations based solely upon their temporal patterns, and (2) to analyze the temporal and seasonal patterns of PM2.5 concentrations in spatially homogenous regions. This study used 24-hr average PM2.5 concentrations measured every third day during a period between 2001 and 2005 at 522 monitoring sites in the continental United States. A k-means clustering algorithm using the correlation distance was used to investigate the similarity in patterns between temporal profiles observed at the monitoring sites. A k-means clustering analysis produced six clusters of sites with distinct temporal patterns that were able to identify and characterize spatially homogeneous regions of the United States. The study also presents a rotated principal component analysis (RPCA) that has been used for characterizing spatial patterns of air pollution and discusses the difference between the clustering algorithm and RPCA.     

Rice straw ash extract, an efficient solvent for regioselective hydrothiolation of alkynes

Environmental Chemistry Letters - Herein, we describe a simple and inexpensive protocol for the hydrothiolation of alkynes. In this context, water extract of rice straw ash (WERSA) has been proven...     

Migration of Cs in tributaries,lake water and sediment of Lago Maggiore (Italy,Switzerland) – analysis and comparison with Lago di Lugano and other lakes

This paper describes the behaviour of ¹³⁷Cs in Lago Maggiore and other pre-alpine lakes as a consequence of atmospheric nuclear weapons testing fallout and the fallout from the nuclear accident in Chernobyl. It presents data on the ¹³⁷Cs distribution in tributaries, lake water, bottom sediments and reveals the role of ¹³⁷Cs as a marker of the sedimentation processes. The run-off of ¹³⁷Cs from the watershed to the lake is described with a simple compartment model. Measurements of the activity concentration of ¹³⁷Cs in sediments are compared with the output of a model (diffusion–convection type) which describes the input of ¹³⁷Cs into and its vertical distribution within the sediment. Varying sedimentation rates (0.05–0.90 g (cm² y)⁻¹) in Lago Maggiore are compared with data of other authors. Sedimentation rates and total distribution coefficients (of about 10⁵ L kg⁻¹) in Lago Maggiore are discussed and compared with those of Lago di Lugano, Lake Constance, and Lake Vorsee.     

Designing a composite indicator for road safety

This study set out to develop a composite road safety indicator for benchmarking countries’ road safety performance, which would combine the main layers of the road safety pyramid which describes the complex nature of road safety activities, performance and outcomes. Four groups of basic safety indicators were considered, which refer to: policy performance (road safety programmes), final road safety outcomes (fatality rates, scope of traffic injury), intermediate outcomes (wearing rates of seat belts, crashworthiness and composition of vehicle fleet, alcohol-impaired driving), and background characteristics of countries (motorization level, population density). The analysis used the data collected for 27 European countries. Weights based on statistical models were used to combine the basic indicators into a composite one. Principal Component Analysis and Common Factor Analysis weighting were examined. The composite indicators, estimated by several methods, enabled us to rank and group the countries according to their safety performance.The analysis revealed that the countries’ ranking based on the composite indicators is not necessarily similar to the traditional ranking of countries based on fatality rates only. Furthermore, it was observed that the indicators belonging to the final outcomes and intermediate outcomes are not uniform in their behaviour. Indicators which were found to be more consistent and influential and termed a ‘core set of basic indicators’ are recommended for future uses. The general conclusion is that the design of a composite road safety indicator in which relevant information from the different components of the road safety pyramid has been captured and weighted is realistic and meaningful. Such an indicator gives a more enriched picture of road safety than a ranking based only on fatality rates, which is the common practice at present. Grouping countries in this process is promising and seems to be preferable to simply ranking countries.     

The use of artificial neural networks to forecast biological atmospheric allergens or pathogens only as Alternaria spores

The monitoring of atmospheric Alternaria spores is of major importance due to their adverse effects on crops and their role as human allergens. Most species act as plant pathogens, prompting considerable economic losses worldwide on important crops such as potato, tomato or wheat. Fungal spores can also have serious detrimental effects on human health, triggering respiratory diseases and allergenic processes. The aim of this study was not only to examine the relationship between the atmospheric Alternaria spore content and the prevailing meteorological parameters, but also to predict the atmospheric Alternaria spore content in the Northwest Spain using a novel data analysis technique, ANNs (Artificial Neural Networks). A Hirst-type LANZONI VPPS 2000 volumetric 7-day recording sampler was used to collect the airborne spores from 1997 to 2008. Neural networks provided us with a good tool for forecasting Alternaria airborne spore concentration, and thus could help the automation of the prediction system in the aerobiological information diffusion to the population suffering from allergic problems or the prevention of considerable economic worldwide losses on important crops. Our proposed model would be applied to different geographical areas; nevertheless, the adjustment of the model, by using the available and adequate variables, would be realised in each case.     

Adaptation of the chlorophycean Dictyosphaerium chlorelloides to stressful acidic, mine metal-rich waters as result of pre-selective mutations

Several species of microalgae, closely related to mesophilic lineages, inhabit the extreme environment (pH 2.5, high levels of metals) of the Spain's Aguas Agrias Stream water (AASW). Consequently, AASW constitutes an interesting natural laboratory for analysis of adaptation by microalgae to extremely stressful conditions. To distinguish between the pre-selective or post-selective origin of adaptation processes allowing the existence of microalgae in AASW, a Luria-Delbrück fluctuation analysis was performed with the chlorophycean Dictyosphaerium chlorelloides isolated from non-acidic waters. In the analysis, AASW was used as selective factor. Preselective, resistant D. chlorelloides cells appeared with a frequency of 1.1 x 10(-6) per cell per generation. AASW-resistant mutants, with a diminished Malthusian fitness, are maintained in non-extreme waters as the result of a balance between new AASW-resistant cells arising by mutation and AASW-resistant mutants eliminated by natural selection (equilibrium at c. 12 AASW-resistants per 10(7) wild-type cells). We propose that the microalgae inhabiting this stressful environment could be the descendents of chance mutants that arrived in the past or are even arriving at the present.