Development of a new aerosol monitoring system and its application in Fukushima nuclear accident related aerosol radioactivity measurement at the CTBT radionuclide station in Sidney of Canada

A high volume aerosol sampler ("Grey Owl") has been designed and developed at the Radiation Protection Bureau, Health Canada. Its design guidance is based on the need for a low operational cost and reliable sampler to provide daily aerosol monitoring samples that can be used as reference samples for radiological studies. It has been developed to provide a constant air flow rate at low pressure drops (∼3 kPa for a day sampling) with variations of less than ±1% of the full scale flow rate. Its energy consumption is only about 1.5 kW for a filter sampling over 22,000 standard cubic meter of air. It has been demonstrated in this Fukushima nuclear accident related aerosol radioactivity monitoring study at Sidney station, B.C. that the sampler is robust and reliable. The results provided by the new monitoring system have been used to support decision-making in Canada during an emergency response.     

Climatic drivers of potential hazards in Mediterranean coasts

This paper studies climatic drivers (air and water temperature, precipitation rates, river discharge, sea level and storm patterns) in four Mediterranean regions: the Catalan-Valencia Coast (Spain), the Oran (Algeria) and Gabès (Tunisia) Gulfs and the western Nile Delta (Egypt). The paper also considers the potential hazards that these drivers can induce. It first analyses climatic trends in the drivers, taking into account the available time series of recorded and simulated meteo-oceanographic data from different sources. Next, it presents the general framework to assess biogeophysical hazards (flooding, erosion, droughts and water quality), followed by a simple and yet robust evaluation of those hazards for the four studied coastal sites. Assuming climate change projections under different scenarios and considering the observed trends in drivers, the resulting erosion rates due to sea-level rise and wave storm effects have been estimated. The Nile and Ebro Deltas, together with the Oran Gulf, are more vulnerable than the Gulfs of Valencia and Gabès. Regarding water quality in terms of (a) precipitation and dissolved oxygen in the water column and (b) sea surface temperature, the results show that the most vulnerable zones for the projected conditions (a) are the Gulfs of Oran, Valencia and Gabès, while the Nile Delta is the region where the decrease in water quality will be less pronounced. For the projected conditions (b), the most vulnerable zone is the Ebro Delta, while the impact in the other three cases will be smaller and of comparable magnitude. Finally, the overall future impact of these hazards (associated to climatic change) in the four sites is discussed in comparative terms, deriving some conclusions.     

Persistence of the fluoroquinolone antibiotic difloxacin in soil and lacking effects on nitrogen turnover

The environmental risks caused by the use of fluoroquinolone antibiotics in human therapeutics and animal husbandry are associated with their persistence and (bio)accessibility in soil. To assess these aspects, we administered difloxacin to pigs and applied the contaminated manure to soil. We then evaluated the dissipation and sequestration of difloxacin in soil in the absence and presence of plants within a laboratory trial, a mesocosm trial, and a field trial. A sequential extraction yielded antibiotic fractions of differing binding strength. We also assessed the antibiotic's effects on nitrogen turnover in soil (potential nitrification and denitrification). Difloxacin was hardly (bio)accessible and was very persistent under all conditions studied (dissipation half-life in bulk soil, >217 d), rapidly forming nonextractable residues. Although varying environmental conditions did not affect persistence, dissipation was accelerated in soil surrounding plant roots. Effects on nitrogen turnover were limited due to the compound's strong binding and small (bio)accessibility despite its persistence.     

Habitat-specific bioaccumulation of methylmercury in invertebrates of small mid-latitude lakes in North America

We examined habitat-specific bioaccumulation of methylmercury (MeHg) in aquatic food webs by comparing concentrations in pelagic zooplankton to those in littoral macroinvertebrates from 52 mid-latitude lakes in North America. Invertebrate MeHg concentrations were primarily correlated with water pH, and after controlling for this influence, pelagic zooplankton had significantly higher MeHg concentrations than littoral primary consumers but lower MeHg than littoral secondary consumers. Littoral primary consumers and pelagic zooplankton are two dominant prey for fish, and greater MeHg in zooplankton is likely sufficient to increase bioaccumulation in pelagic feeders. Intensive sampling of 8 lakes indicated that habitat-specific bioaccumulation in invertebrates (of similar trophic level) may result from spatial variation in aqueous MeHg concentration or from more efficient uptake of aqueous MeHg into the pelagic food web. Our findings demonstrate that littoral-pelagic differences in MeHg bioaccumulation are widespread in small mid-latitude lakes.     

Assessment of the abiotic transformation of 17β-estradiol in the presence of vegetable matter

A study using 17β-¹⁴C₄-estradiol (¹⁴C-E2) was performed to confirm and characterize the catalytic transformation of estrogens in the presence of a model vegetable matter (namely rabbit food) as a surrogate material for vegetable wastes found in sewage. Results corroborated the occurrence of an abiotic transformation. Unknown transformation byproduct(s) accounted, respectively, for 38% and 9% of the initial radioactivity in liquid and extractable solid phases after 72 h; on the other hand, only 15% and 7% of this radioactivity corresponded to ¹⁴C-E2 in those same matrices. Mass balance was closed including the radioactivity irreversibly bounded to the solid phase. Formation of ¹⁴C₄-estrone was monitored by Liquid Chromatography with tandem Mass Spectrometry detection; negative results were found in all sampling events. This process could be harnessed to optimize sustainable technologies for the removal of phenolic microcontaminants from wastewater.     

Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium-France)

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg⁻¹, 12 ng TEQ kg⁻¹ and 5.1 ng TEQ kg⁻¹. Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs.     

Phyt'Eaux Cités: application and validation of a programme to reduce surface water contamination with urban pesticides

This paper presents first results of Phyt’Eaux Cités, a program put in place by the local water supply agency, the SEDIF (Syndicat des Eaux d’Ile-de-France), in collaboration with 73 local authorities, private societies and institutional offices (365 km²). The challenges included: measurement of the previous surface water contamination, control of urban pesticide applications, prevention of pesticide hazard on users and finally a overall reduction of surface water contamination. An inquiry on urban total pesticide amount was coupled with a surface water bi-weekly monitoring to establish the impact of more than 200 molecules upon the Orge River. For 2007, at least 4400 kg and 92 type of pesticides (essentially herbicides) were quantified for all urban users in the Phyt’Eaux Cités perimeter. At the outlet of the Orge River (bi-weekly sampling in 2007), 11 molecules were always detected above 0.1 μg L⁻¹. They displayed the mainly urban origin of pesticide surface water contamination. Amitrole, AMPA (Aminomethyl Phosphonic Acid), demethyldiuron, diuron, glyphosate and atrazine were quantified with a 100% of frequency in 2007 and 2008 at the Orge River outlet. During the year, peaks of contamination were also registered for MCCP, 2,4 MCPA, 2,4 D, triclopyr, dichlorprop, diflufènican, active substances used in large amount in the urban area. However, some other urban molecules, such as isoxaben or flazasulfuron, were detected with low frequency. During late spring and summer, contamination patterns and load were dominated by glyphosate, amitrole and diuron, essentially applied by cities and urban users. Both isoproturon and chlortoluron were quantified during autumn and winter months according to upstream agricultural practices. In conclusion, 3 years after the beginning of this programme, the cities reduced the use of 68% of the total pesticide amount. An improvement on surface water quality was found from 2008 and during 2009 for all pesticides. In particular, glyphosate showed a decrease of the load above 60% in 2008, partly related to the Phyt’Eaux Cités action.     

Uncertainty requirements of the European Union’s Industrial Emissions Directive for monitoring sulfur dioxide emissions: Implications from a blind comparison of sulfate measurements by accredited laboratories

When annual average PM_2.5 (fine particulate matter sized 2.5 microns and less) data for 2005 became available in April 2006 and the 3-yr average PM_2.5 concentration in an area just north of the Houston Ship Channel reached 15.0 µg/m³, the Texas Commission on Environmental Quality (TCEQ) initiated daily collection of quartz fiber as well as Teflon PM_2.5 filter samples for chemical speciation analysis. The purpose of the chemical speciation analysis was to use the speciation data, together with meteorological data and hourly TEOM (tapered element oscillating microbalance) PM_2.5 mass data, to identify the causes of the high PM_2.5 concentrations affecting the monitoring site and the neighborhood. The ultimate purpose was to target emission reduction efforts to sources contributing to the high measured PM_2.5 concentrations. After a year of data collection, it was recognized that a specific source, unpaved driveways and loading areas along the Ship Channel and dirt tracked onto Clinton Drive, the main artery running east-west north of the Ship Channel, were the primary cause for the Clinton Drive site's measuring PM_2.5 concentrations significantly higher than other sites in Houston. The source characterization and remediation steps that have led to sustained reduced concentrations are described in this paper.

Implications: With PM_2.5 exceedances it can be essential to have or develop chemical speciation data as part of the process of identifying the source types causing exceedances of an annual standard. Positive matrix factorization (PMF) analysis proved to be a powerful tool that identified the two locally emitted species contributing to exceedances, which did not occur at other sites in the region. They were calcium sulfate (gypsum), an industrial by-product, and soil minerals. Other data analysis approaches were necessary to distinguish North African dust events, which PMF failed to identify.     

Control of Organic Emissions from Surface Coating Operations

ABSTRACT

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. “Non-ideal flow” indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor.

The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH₃ removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.