Dietary exposure of rainbow trout to 8:2 and 10:2 fluorotelomer alcohols and perfluorooctanesulfonamide: Uptake, transformation and elimination

The bioaccumulation of perfluorooctanesulfonamide (PFOSA) and two fluorotelomer alcohols (8:2 FTOH, 10:2 FTOH) by rainbow trout (Oncorhynchus mykiss) through dietary exposure, including depuration rates and metabolism was investigated. Concentrations in the spiked feed ranged from 10.9 μg g⁻¹ wet weight (wet wt) for PFOSA and 6.7 μg g⁻¹ wet wt for 8:2 FTOH to 5.0 μg g⁻¹ wet wt for 10:2 FTOH. Trout was fed at 1.5% body weight per day for 30 d and depuration was followed for up to 30 d following previously published dietary exposure protocols. Perfluorooctanesulfonate (PFOS) was the major perfluoroalkylsulfonate (PFSA) detected in fish following dietary exposure to PFOSA. Half-lives of PFOS and PFOSA were 16.9 ± 2.5 and 6.0 ± 0.4 d, respectively. A biomagnification factor (BMF) of 0.023 was calculated for PFOSA which indicates that dietary exposure to PFOSA does not result in biomagnification in the rainbow trout. PFOS had a BMF of 0.08. The fluorotelomer saturated acids (8:2 FTCA, 10:2 FTCA) and fluorotelomer unsaturated acids (8:2 FTUCA, 10:2 FTUCA) were the major products detected in rainbow trout following dietary exposure to 8:2 FTOH and 10:2 FTOH, respectively. Half-lives were 3.7 ± 0.4, 2.1 ± 0.5, 3.3, and 1.3 d for 10:2 FTCA, 10:2 FTUCA, 8:2 FTCA, and 8:2 FTUCA, respectively. Small amounts of perfluorooctanoate (PFOA) and perfluorodecanoate (PFDA) were also detected in the FTOH exposed fish.     

Multi-element accumulation near Rumex crispus roots under wetland and dryland conditions

Rumex crispus was grown under wet and dry conditions in two-chamber columns such that the roots were confined to one chamber by a 21 μm nylon mesh, thus creating a soil-root interface (‘rhizoplane’). Element concentrations at 3 mm intervals below the ‘rhizoplane’ were measured. The hypothesis was that metals accumulate near plant roots more under wetland than dryland conditions. Patterns in element distribution were different between the treatments. Under dryland conditions Al, Ba, Cu, Cr, Fe, K, La, Mg, Na, Sr, V, Y and Zn accumulated in soil closest to the roots, above the ‘rhizoplane’ only. Under wetland conditions Al, Fe, Cr, K, V and Zn accumulated above as well as 3 mm below the ‘rhizoplane’ whereas La, Sr and Y accumulated 3 mm below the ‘rhizoplane’ only. Plants on average produced 1.5 times more biomass and element uptake was 2.5 times greater under wetland compared to dryland conditions.     

Factors Affecting Resistivity in Electrostatic Precipitation

The following material is taken from a new book, “The Art of Electrostatic Precipitation,” authored by Mr. Katz and based on his 30 years of field experience with the subject. The book provides practical information on maintaining and upgrading precipitators; chapter titles include fundamentals, operation and maintenance, trouble solving, corrosion factors, methods to improve performance, test evaluation techniques, gas distribution and conditioning, case histories, and optimum designs.     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Quantifying methane emission from fugitive sources by combining tracer release and downwind measurements – A sensitivity analysis based on multiple field surveys

Using a dual species methane/acetylene instrument based on cavity ring down spectroscopy (CRDS), the dynamic plume tracer dispersion method for quantifying the emission rate of methane was successfully tested in four measurement campaigns: (1) controlled methane and trace gas release with different trace gas configurations, (2) landfill with unknown emission source locations, (3) landfill with closely located emission sources, and (4) comparing with an Fourier transform infrared spectroscopy (FTIR) instrument using multiple trace gasses for source separation. The new real-time, high precision instrument can measure methane plumes more than 1.2 km away from small sources (about 5 kg h^?1) in urban areas with a measurement frequency allowing plume crossing at normal driving speed. The method can be used for quantification of total methane emissions from diffuse area sources down to 1 kg per hour and can be used to quantify individual sources with the right choice of wind direction and road distance. The placement of the trace gas is important for obtaining correct quantification and uncertainty of up to 36% can be incurred when the trace gas is not co-located with the methane source. Measurements made at greater distances are less sensitive to errors in trace gas placement and model calculations showed an uncertainty of less than 5% in both urban and open-country for placing the trace gas 100 m from the source, when measurements were done more than 3 km away. Using the ratio of the integrated plume concentrations of tracer gas and methane gives the most reliable results for measurements at various distances to the source, compared to the ratio of the highest concentration in the plume, the direct concentration ratio and using a Gaussian plume model. Under suitable weather and road conditions, the CRDS system can quantify the emission from different sources located close to each other using only one kind of trace gas due to the high time resolution, while the FTIR system can measure multiple trace gasses but with a lower time resolution.     

Description and evaluation of a model of deposition velocities for routine estimates of air pollutant dry deposition over North America.: Part I: model development

This paper describes the development of a detailed dry deposition model for routine computation of dry deposition velocities of SO₂, O₃, HNO₃ and fine particle SO₄²⁻ across much of North America. Four different dry deposition/surface exchange sub-models have been combined with the current Canadian weather forecast model (Global Environmental Multiscale model) with a 3 h time resolution and a horizontal spatial resolution of 35 km. The present model uses the US Geological Survey North American Land Cover Characteristics data to obtain fourteen different land use and five seasonal categories. The four sub-models used are a multi-layer model for gaseous species over taller canopy land-use types, a big-leaf model for gaseous species over lower canopies (including bare soil and water) and for HNO₃ under all surface types and, two different models for SO₄²⁻, one for tall canopies and the other for short canopies. All necessary parameters for each sub-model, chemical species, land-use and seasonal categories have been selected from available data libraries or from the values reported in the literature. The purpose for developing this model (referred to as the Routine Deposition Model (RDM)), when coupled with air concentration data, is to provide estimates of seasonal dry deposition, which can be combined with wet deposition to produce total deposition estimates. Model theory is discussed in this paper and model sensitivity tests and results will be presented in a companion paper.     

Aesthetic and affective effects of vocal and traffic noise on natural landscape assessment

National parks have mandates both to preserve and protect natural settings and to assist visitors in viewing and interacting with those settings. Considerable scholarship has examined the trade-offs between preservation and recreation goals, such as protection of a natural setting when some visitors want to experience it from noisy aircraft or ground vehicles. The current project expands on previous noise research that showed the presence of aircraft noise to be detrimental to aesthetic and affective environmental assessments. Participants rated 25 scenes under quiet conditions or while hearing 45 dB(A) or 60 dB(A) of either natural sounds (bird calls, breeze through foliage), natural sounds with aircraft sounds, natural sounds with ground traffic sounds, or natural sounds with human voices. Results indicated that the presence of any anthropogenic noise–air traffic, ground traffic, or voices–negatively impacted environmental assessments, and more so at louder levels, while the natural soundscape had little to no effect on assessments. Additionally, the presence of air traffic, ground traffic, and human voices significantly decreased participant ratings of serenity while also increasing ratings of hostility. These effects were strongest for scenes that were high in scenic beauty. Results are discussed in the context of sound quality management in national parks and other settings.     

Secondary ozonides of substituted cyclohexenes: a new class of pollutants characterized by collision-induced dissociation mass spectrometry using negative chemical ionization

Recent studies indicate that secondary ozonides of cyclic alkenes are formed in atmospheric reactions and may be relatively stable. The secondary ozonides (SOZs) of cyclohexene (1), 1-methylcyclohexene (2), 4-isopropyl-1-methylcyclohexene (3) and 4-isopropenyl-1-methylcyclohexene (limonene) (4) have been characterized by rapid gas chromatography electron ionization (EI), negative and positive chemical ionization (CI: ammonia, isobutane and methane) and collision-induced dissociation (CID) mass spectrometry. Both EI and positive CI spectra were found unsuitable for reproducible analysis. However, negative CI showed stable (M−H)⁻ ions with minor fragmentation. CID of the (M−H)⁻ ions resulted in simple and reproducible fragmentation patterns for all four SOZs with loss of m/z 18, 44 and 60, tentatively assigned as H₂O, CO₂ and C₂H₄O₂ or CO₃, respectively. Thus, negative CI-MS–MS in combination with rapid gas chromatography is the preferred method for identification of secondary ozonides of cyclohexenes.     

The impact of maternal plasma DNA fetal fraction on next generation sequencing tests for common fetal aneuploidies

Maternal plasma contains circulating cell-free DNA fragments originating from both the mother and the placenta. The proportion derived from the placenta is known as the fetal fraction. When measured between 10 and 20 gestational weeks, the average fetal fraction in the maternal plasma is 10% to 15% but can range from under 3% to over 30%. Screening performance using next-generation sequencing of circulating cell-free DNA is better with increasing fetal fraction and, generally, samples whose values are less than 3% or 4% are unsuitable. Three examples of the clinical impact of fetal fraction are discussed. First, the distribution of test results for Down syndrome pregnancies improves as fetal fraction increases, and this can be exploited in reporting patient results. Second, the strongest factor associated with fetal fraction is maternal weight; the false negative rate and rate of low fetal fractions are highest for women with high maternal weights. Third, in a mosaic, the degree of mosaicism will impact the performance of the test because it will reduce the effective fetal fraction. By understanding these aspects of the role of fetal fraction in maternal plasma DNA testing for aneuploidy, we can better appreciate the power and the limitations of this impressive new methodology. © 2013 John Wiley & Sons, Ltd.     

Application for a newly developed high-capacity NOx denuder: low-NOx diesel transformation experiments

To conduct low oxides of nitrogen (NOx) chamber experiments with modern diesel emissions (DE), a high-capacity NO, denuder was developed and used at the European Photoreactor (EUPHORE) outdoor simulation chamber. The denuder displayed a sufficient NOx storage capacity for use with DE, and efficient removal of NO, during injections of DE was achieved (>98%). Degradation of the denuder performance after repeated regeneration by heating (400 degrees C) and flushing with an air/oxygen ratio of 2:1 was not observed for a total of nine experiments. Evaluation of dark (with chamber cover closed) experiments (four in total) with and without the denuder in-line revealed some reduction (22%) of diesel particulate matter (DPM) with use of the denuder, most likely a result of impaction or settling of DPM during DE transit. However, DPM reduction may have also been a result of reductions in effective load of the engine-dyno system during the DE injections. Extensive chemical characterization of DPM revealed no significant perturbation of major compound groups associated with denuder use, except for nitrated polyaromatic hydrocarbon (NPAH) concentrations. The implications of high-NOx experiments without the use of a NOx denuder are discussed.