The ozone source–receptor model – A tool for UK ozone policy

The Ozone Source–Receptor Model (OSRM) is a Lagrangian trajectory model developed to describe photochemical ozone production in the UK. The OSRM builds on existing boundary layer trajectory models used previously for assisting the development of UK ozone policy, but has a number of notable differences. A novel feature of the OSRM is a surface conversion module to represent the vertical gradient in ozone arising from chemical loss and deposition to the surface. This has significantly improved the performance of the model, especially in urban areas. In this paper, the modelling system is described and its performance against measured ozone concentrations and metrics and other UK ozone models is discussed. The model has been used to calculate future ozone concentrations in the UK and thus to assess a number of possible control measures developed for the UK Air Quality Strategy.     

Mobile source emission inventories--monthly or annual average inputs to MOBILE6?

In many urban areas, on-road vehicles are the biggest contributing source category of volatile organic compounds (VOCs) and nitrogen oxides (NOx). Based on a recently completed emission inventory study for three counties in central Florida, the major source by far of anthropogenic VOCs and NOx was on-road mobile sources, even though other sources (such as construction equipment, lawn and garden equipment, and various point sources) were also significant. Although there is specific guidance for conducting an ozone-season inventory for mobile sources, there is a lack of detailed guidance as to how to employ the U.S. Environmental Protection Agency's (EPA) latest mobile source emission factor program, MOBILE6, for an annual inventory. Several of the MOBILE6 inputs that significantly influence emission factors (e.g., temperature) can vary widely throughout the year, and the annual average value may not be appropriate. Rather, it may be better to utilize monthly values of these parameters. This paper investigated the sensitivity of the annual emission inventory results to using annual or monthly values of temperature, Reid Vapor Pressure of gasoline, and humidity. The results show that, for a three-county area in central Florida representing metropolitan Orlando, the annual emission inventory based on the sum of individual monthly averages is not significantly different from that calculated using one set of annual average inputs to MOBILE6.     

VOC source–receptor relationships in Houston during TexAQS-II

During the TRAMP field campaign in August–September 2006, C₂–C₁₀ volatile organic compounds (VOCs) were measured continuously and online at the urban Moody Tower (MT) site. This dataset was compared to corresponding VOC data sets obtained at six sites located in the highly industrialized Houston Ship Channel area (HSC). Receptor modeling was performed by positive matrix factorization (PMF) at all sites. Conditional probability functions (CPF) were used to determine the origin of the polluted air masses in the Houston area. A subdivision into daytime and nighttime was carried out to discriminate photochemical influences. Eight main source categories of industrial, mobile, and biogenic emissions were identified at the urban receptor site, seven and six, respectively, at the different HSC sites. At MT natural gas/crude oil contributed most to the VOC mass (27.4%), followed by liquefied petroleum gas (16.7%), vehicular exhaust (15.3%), fuel evaporation (14.3%), and aromatics (13.4%). Also petrochemical sources from ethylene (4.7%) and propylene (3.6%) play an important role. A minor fraction of the VOC mass can be attributed to biogenic sources mainly from isoprene (4.4%). Based on PMF analyses of different wind sectors, the total VOC mass was estimated to be twofold at MT with wind directions from HSC compared to air from a typical urban sector, for petrochemical compounds more than threefold. Despite the strong impact of air masses influenced by industrial sources at HSC, still about a third of the total mass contributions at MT can be apportioned to other sources, mainly motor vehicles and aromatic solvents. The investigation of diurnal variation in combination with wind directional frequencies revealed the greatest HSC impact at the urban site during the morning, and the least during the evening.     

Platitudes or Performance?

Industry, government, and the public have come a long way in establishing the dialogue that is necessary if the reservations each has had of the others’ motives are to be dispelled. However, each tends to fall into a routine of accusations, charges, counter charges, and rebuttals. This paper deals with the action which must be forthcoming from industry if good community relations are to be maintained and the public interest is to be served.     

Polybrominated diphenyl ethers in aircraft cabins--a source of human exposure?

Commercial aircrafts need a high degree of fire protection for passenger safety. Brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs), may be used for this purpose. Because PBDEs readily absorb to dust particles, aircraft crew and passengers may receive significant PBDEs exposure via inhalation. The aims of this work were to assess whether PBDEs could be found in aircraft cabin dust and whether serum levels of PBDEs increased in passengers after long-distance flights. Hence nine subjects on intercontinental flights collected cabin dust samples, as well as donated blood samples before departure and after return to Sweden. Two subjects who were domestic frequent flyers were also investigated. The levels of PBDEs in dust and serum were determined by GC/MS in electron capture negative ionization (ECNI) mode. Authentic reference substances were used for identification and quantitation. PBDEs were found in all aircraft dust samples at high concentrations, higher than in common household dust. Congener patterns indicated that the technical products PentaBDE, OctaBDE and DecaBDE were used in the aircrafts. Serum concentrations in the travellers were similar to those observed in Swedish residents in general. Post-travel serum levels of BDE-28, BDE-99, BDE-100, BDE-153, and BDE-154 were significantly higher (p<0.05) than concentrations prior to travel. The findings from this pilot study call for investigations of occupational exposures to PBDEs in cabin and cockpit crews.     

Hazard mitigation or mitigation hazard?

BACKGROUND, AIM AND SCOPE: Transgenic oilseed rape (Brassica napus L.; OSR) is estimated to be environmentally and economically problematic because volunteers and ferals occur frequently and because of its hybridisation potential with several wild and weedy species. A proposed mitigation strategy aims to reduce survival, in particular in conventional OSR crops, by coupling the transgenic target modification with a dwarfing gene to reduce competitive fitness. Our study allowed us to access potential ecological implications of this strategy. MATERIALS AND METHODS: On a large scale (>500 km(2)), we recorded phenological and population parameters of oilseed rape plants for several years in rural and urban areas of Northern Germany (Bremen and surroundings). The characterising parameter were analysed for differences between wild and cultivated plants. RESULTS: In rural areas, occurrences of feral and volunteer OSR together had an average density of 1.19 populations per square kilometre, in contrast to urban areas where we found 1.68 feral populations per square kilometre on average. Throughout the survey, the vegetation cover at the locations with feral OSR ranged from less than 10% to 100%. Our investigations gave clear empirical evidence that feral OSR was, on average, at least 41% smaller than cultivated OSR, independent of phenological state after onset of flowering. DISCUSSION: The findings can be interpreted as phenotypic adaptation of feral OSR plants. Therefore, it must be asked whether dwarfing could be interpreted as an improvement of pre-adaptation to feral environments. In most of the sites where feral plants occurred, germination and establishment were in locations with disturbed vegetation cover, allowing initial growth without competition. Unless feral establishment of genetically modified dwarfed traits are specifically studied, it would not be safe to assume that the mitigation strategy of dwarfing also reduces dispersal in feral environments. CONCLUSIONS AND RECOMMENDATIONS: With respect to OSR, we argue that the proposed mitigation approach could increase escape and persistence of transgene varieties rather than reducing them. We conclude that the development of effective hazard mitigation measures in the risk evaluation of genetically modified organisms requires thorough theoretical and empirical ecological analyses rather than assumptions about abstract fitness categories that apply only in parts of the environment where the plant can occur.     

Is meltwater from Alpine glaciers a secondary DDT source for lakes?

A sharp increase in 2005 of pp'DDT and its metabolites was observed in mussels and fish from lakes Como and Iseo, the main glacier-fed southern Alpine lakes. DDTs in zebra mussels (Dreissena polymorpha) were more than 150 times higher than levels in 2003, and concentrations in pelagic fish (0.12 mgkg(-1) w.w.) exceeded the Italian safety threshold for human consumption (0.05 mgkg(-1) w.w.). The histological examination of the ovaries revealed many mussels with oocyte degeneration throughout the studied period. Prior to being banned in Italy in 1978, DDT was used in large amounts for fruit-tree treatment from the 1950s to 1970s in valleys just below the glaciers. Since glacier volume was increasing at that time and then continuously retreated, meltwater should be the main cause of the pollution peak recently observed in biota of downstream lakes. PCBs did not peak in biota tissues to a comparable extent probably because local sources were not as important as for DDTs.     

Quantification on source/receptor relationship of primary pollutants and secondary aerosols from ground sources—Part I. Theory

A new algorithm has been derived for trajectory models to determine the transfer coefficient of each source along or adjacent to a trajectory and to calculate the concentrations of SO₂, NO_x, sulfate, nitrate, fine particulate matter (PM) and coarse PM at a receptor. The transfer coefficient t_f (s m⁻¹) is defined to be the ratio between the contributed concentration ΔC (μg m⁻³) to the receptor from a ground source and the emission rate of the source q (μg m⁻² s⁻¹) at a grid, i.e. t_f≡ΔC/q. The model is developed by combining with a backward trajectory scheme and a circuit-type's parameterization. First, the transfer coefficients of grids along or adjacent a back-trajectory are calculated. Then, the contributed concentration of each emission grid is determined by multiplying its emission rate with the transfer coefficient of the grid. Finally, the concentration at the receptor is determined by the summation of all the contributed concentrations within the domain of simulation.     

?Kochsalz verbieten?“ – ein nachdenkliches Vorwort zur Beitragsserie Regulatorische ?kotoxikologie

Zusammenfassung  Ziel der Beitragsserie „regulatorische ?kotoxikologie“ ist es, (i) die gesetzlichen Grundlagen, Prinzipien und Instrumente der ?kotoxikologischen Stoff- und Risikobewertung zu erl?utern, (ii) die Denk- und Arbeitsweisen von Regulatoren zu beschreiben, (iii) die Abstimmungs- und Entscheidungsprozesse in der Stoff- und Risikobewertung nachzuzeichnen, (iv) unterschiedliche Standpunkte zu strittigen regulatorischen Themen zu vermitteln und (v) aktuelle Entwicklungen in der regulatorischen ?kotoxikologie aufzuzeigen. Die Serie umfasst Diskussionsbeitr?ge und Originalarbeiten von Autorinnen und Autoren aus den ma?geblich beteiligten Interessensgruppen (Beh?rde, Industrie, Akademie, Umweltverb?nde), wobei mit unterschiedlichen Fragestellungen s?mtliche relevanten Stoffgruppen, Methoden und stoffgesetzlichen Regelungsbereiche (Biozide, Pflanzenschutzmittel, Arzneimittel, Abwasserreinigung, REACH, Wasserrahmenrichtlinie) adressiert werden.      

Tetrabromobisphenol A: a neurotoxicant or not?

Environmental Science and Pollution Research - Although some regulatory agencies have claimed that consumer exposures to tetrabromobisphenol A (TBBPA) are not likely to cause adverse health effects...     

Are deep eutectic solvents benign or toxic?

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required.     

Condensed Sulfur Trioxide—Particulate or Vapor?

Sulfuric acid from condensed sulfur trioxide (SO₃) has been found in the filtering medium used in the EPA/APCO, WP-50, and high-volume sampling methods. The amount of sulfuric acid ranged from 1 8 to 78% of the total particulate matter found when sampling emissions from oil-fired boilers. These levels were high enough to determine whether a unit is in compliance with regulations. A question is raised as to whether condensed sulfur trioxide should be included in particulate measurements or eliminated after analyzing the filter medium.     

Population exposure and mortality due to regional background PM in Europe – Long-term simulations of source region and shipping contributions

This paper presents the contribution to population exposure (PE) of regional background fine primary (PPM_2.5) and secondary inorganic (SIA) particulate matter and its impact on mortality in Europe during 1997–2003 calculated with a chemistry transport model. Contributions to concentrations and PE due to emissions from shipping, Western (WEU), Eastern (EEU), and Northern Europe are compared.WEU contributes about 40% to both PPM_2.5 and SIA concentrations, whereas the EEU contribution to PPM_2.5 is much higher (43% of total PPM_2.5) than to SIA (29% of total SIA). The population weighted average concentration (PWC) of PPM_2.5 is a factor of 2.3 higher than average (non-weighted) concentrations, whereas for SIA the PWC is only a factor 1.6 higher. This is due to PPM_2.5 concentrations having larger gradients and being relatively high over densely populated areas, whereas SIA is formed outside populated areas. WEU emissions contribute relatively more than EEU to PWC and mortality due to both PPM_2.5 and SIA in Europe.The number of premature deaths in Europe is estimated to 301 000 per year due to PPM_2.5 exposure and 245 000 due to SIA, despite 3.3 times higher average SIA concentrations. This is due to population weighting and assumed (and uncertain) higher relative risk of mortality for PPM_2.5 components (2.8 times higher RR for PPM_2.5). This study indicates that it might be more efficient, for the health of the European population, to decrease primary PM emissions (especially in WEU) than to decrease precursors of SIA, but more knowledge on the toxicity of different PM constituents is needed before firm conclusions can be drawn.     

Air filters from HVAC systems as possible source of volatile organic compounds (VOC) – laboratory and field assays

The emission of volatile organic compounds (VOC) from air filters of HVAC systems was to be evaluated. In a first study carbonyl compounds (14 aldehydes and two ketones) were measured by reacting them with 2,4-dinitrophenylhydrazine (DNPH). Analysis was done by HPLC and UV detection. In laboratory experiments pieces of used and unused HVAC filters were incubated in test chambers. Filters to be investigated were taken from a filter bank of a large HVAC system in the centre of Berlin. First results show that – among those compounds – formaldehyde and acetone were found in higher concentrations in the test chambers filled with used filters in comparison to those with unused filters. Parallel field measurements were carried out at the prefilter and main filter banks of the two HVAC systems. Here measurements were carried out simultaneously before and after the filters to investigate whether those aldehydes or ketones arise from the filter material on site. Formaldehyde and acetone significantly increased in concentration after the filters of one HVAC system. In parallel experiments microorganisms were proved to be able to survive on air filters. Therefore, a possible source of formaldehyde and acetone might be microbes.     

Simulation of a line source by a moving-point source of droplets—I. Theory

The simulation of a line source of aerosol by a moving-point source is set within a mathematical framework that combines characteristics of the boundary-layer turbulence and of the moving source. Comparison of theory with experimental observation shows (i) that a moving source can simulate a true line source and (ii) that the variability in measurements is substantially as predicted by the theory. By regarding a line source as the limiting case of a moving-point source with a very small period of traverse, an expression is derived for the variability in measurements downwind of a true line source.     

Bound residues: environmental solution or future problem?

The paper examines the issue of bound residues from the viewpoint of the risk assessment procedures employed for environmental protection. It considers, on one hand, the evidence that such residues are so tightly bound to soil organic matter as to be essentially unavailable; and on the other, the perspective that we should not be loading up the environment with compounds whose future behaviour and release we cannot predict. Existing knowledge of the mechanisms by which residues bind to soil organic matter suggests that release will be closely dependent on soil organic matter breakdown. Simple models of organic matter turnover suggest that the release following single applications of individual compounds will be very slow; but the significance of releases following repeated application over many years of a number of compounds needs to be investigated further. Applying environmental risk assessment techniques is complicated by the difficulty in identifying parent molecules and potential metabolites in the bound residue fraction. The paper concludes that for single additions of individual compounds, bound residues probably do represent an environmental solution. But the long-term significance of bound residues formed from multiple additions of a number of compounds is less clear. The paper recommends that future work should emphasise the biological significance of such residues and their release.