Teflon Filters Research Articles

Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: systematic intercomparison of calibration methods for US measurement network samples

Abstract. Peak fitting (PF) and partial least squares (PLS) regression have been independently developed for estimation of functional groups (FGs) from Fourier transform infrared (FTIR) spectra of ambient aerosol collected on Teflon filters. PF is a model that quantifies the functional group composition of the ambient samples by fitting individual Gaussian line shapes to the aerosol spectra. PLS is a data-driven, statistical model calibrated to laboratory standards of relevant compounds and then extrapolated to ambient spectra. In this work, we compare the FG quantification using the most widely used implementations of PF and PLS, including their model parameters, and also perform a comparison when the underlying laboratory standards and spectral processing are harmonized. We evaluate the quantification of organic FGs (alcohol COH, carboxylic COOH, alkane CH, carbonyl CO) and ammonium, using external measurements (organic carbon (OC) measured by thermal optical reflectance (TOR) and ammonium by balance of sulfate and nitrate measured by ion chromatography). We evaluate our predictions using 794 samples collected in the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network (USA) in 2011 and 238 laboratory standards from Ruthenburg et al. (2014) (available at https://doi.org/10.1016/j.atmosenv.2013.12.034). Each model shows different biases. Overall, estimates of OC by FTIR show high correlation with TOR OC. However, PLS applied to unprocessed (raw spectra) appears to underpredict oxygenated functional groups in rural samples, while other models appear to underestimate aliphatic CH bonds and OC in urban samples. It is possible to adjust model parameters (absorption coefficients for PF and number of latent variables for PLS) within limits consistent with calibration data to reduce these biases, but this analysis reveals that further progress in parameter selection is required. In addition, we find that the influence of scattering and anomalous transmittance of infrared in coarse particle samples can lead to predictions of OC by FTIR which are inconsistent with TOR OC. We also find through several means that most of the quantified carbonyl is likely associated with carboxylic groups rather than ketones or esters. In evaluating state-of-the-art methods for FG abundance by FTIR, we suggest directions for future research.

An open platform for Aerosol InfraRed Spectroscopy analysis – AIRSpec

Abstract. AIRSpec is a platform consisting of several chemometric packages developed for analysis of Fourier transform infrared (FTIR) spectra of atmospheric aerosols. The packages are accessible through a browser-based interface, which also generates the necessary input files based on user interactions for provenance management and subsequent use with a command-line interface. The current implementation includes the task of baseline correction, organic functional group (FG) analysis, and multivariate calibration for any analyte with absorption in the mid-infrared. The baseline correction package uses smoothing splines to correct the drift of the baseline of ambient aerosol spectra given the variability in both environmental mixture composition and substrates. The FG analysis is performed by fitting individual Gaussian line shapes for alcohol (aCOH), carboxylic acid (COOH), alkane (aCH), carbonyl (CO), primary amine (aNH2), and ammonium (ammNH) for each spectrum. The multivariate calibration model uses the spectra to estimate the concentration of relevant target variables (e.g., organic or elemental carbon) measured with different reference instruments. In each of these analyses, AIRSpec receives spectra and user choices on parameters for model computation; input files with parameters that can later be used with a command-line interface for batch computation are returned together with diagnostic figures and tables in text format. AIRSpec is built using the open-source software consisting of R and Shiny and is released under the GNU Public License v3. Users can download, modify, and extend the package, or access its functionality through the web application (http://airspec.epfl.ch, last access: 3 April 2019) hosted at the École polytechnique fédérale de Lausanne (EPFL). AIRSpec provides a unified framework by which different chemometric techniques can be shared and accessed, and its underlying suite of packages provides the basic functionality for extending the platform with new types of analyses. For example, basic functionality includes operations for populating and accessing spectra residing in in-memory arrays or relational databases, input and output of spectra and results of computation, and user interface development. Moreover, AIRSpec facilitates the exploratory work, can be used by FTIR spectra acquired with different methods, and can be extended easily with new chemometric packages when they become available. Therefore AIRSpec provides a framework for centralizing and disseminating such algorithms. This paper describes the modular architecture and provides examples of the implemented packages using the spectra of aerosol samples collected on PM2.5 polytetrafluoroethylene (Teflon) filters.

Measurement of dust-borne MRSA in pig farms using different approaches.

To obtain knowledge about (i) how to sample airborne methicillin-resistant Staphylococcus aureus (MRSA) and dust in the pig farm environment including effects of sampler on (a) measured exposure, (b) MRSA survival and (c) spatial and temporal variation in exposure, and (ii) the association between exposure to MRSA, dust and optical density OD. Airborne dust was sampled on five pig farms using five active and one passive samplers. Staphylococcus aureus and MRSA (as a subset of S. aureus) were quantified using selective agar media and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The Andersen sampler, electrostatic dust collectors (EDC), and Gesamtstaubprobenahme (GSP) and Institute of Occupational Medicine samplers with polycarbonate or Teflon filters were applicable for sampling airborne MRSA. The half-life of MRSA was not reduced by active sampling. A significant correlation was found between dust and S. aureus exposure within, but not between, farm section and farms. A significant spatial and temporal variation in dust and MRSA exposure was found within a stable. The dust sampling rate and the concentration of MRSA in the sampled dust decreased after 5days of sampling. Sampling using the GSP can be performed for 1h without affecting the following half-life of MRSA. Sampling for MRSA using the EDC should not exceed 3days due to overloading and the die-off of MRSA. The measurement of OD may be used as a proxy measure for dust exposure. To obtain knowledge about potential exposure, samples should be taken repeatedly and in different areas within a stable section. Sampling method, sampling time and number of samples taken, but not force of airflow on the filter, influence the measured potential exposure to MRSA and dust.

Bioaerosol and surface sampling for the surveillance of influenza A virus in swine

Influenza A virus in swine is of significant importance to human and veterinary public health. Environmental sampling techniques that prove practical would enhance surveillance for influenza viruses in swine. The primary objective of this study was to demonstrate the feasibility of bioaerosol and surface sampling for the detection of influenza virus in swine barns with a secondary objective of piloting a mobile application for data collection. Sampling was conducted at a large swine operation between July 2016 and August 2017. Swine oral fluids and surface swabs were collected from multiple rooms. Room-level air samples were collected using four bioaerosol samplers: a low volume polytetrafluoroethylene (PTFE) filter sampler, the National Institute for Occupational Safety and Health's low volume cyclone sampler, a 2-stage Andersen impactor and/or one high volume cyclonic sampler. Samples were analysed using quantitative RT-PCR. Data and results were reported using a mobile data application. Eighty-nine composite oral fluid samples, 70 surface swabs and 122 bioaerosol samples were analysed. Detection rates for influenza virus RNA in swine barn samples were 71.1% for oral fluids, 70.8% for surface swabs and 71.1% for the PTFE sampler. Analysis revealed a statistically significant relationship between the results of the PTFE sampler and the surface swabs with oral fluid results (p<0.001 and p<0.01 respectively). In addition, both the PTFE sampler (p<0.01) and surface swabs (p=0.03) significantly correlated with, and predicted oral fluid results. Bioaerosol sampling using PTFE samplers is an effective hands-off approach for detecting influenza virus activity among swine. Further study is required for the implementation of this approach for surveillance and risk assessment of circulating influenza viruses of swine origin. In addition, mobile data collection stands to be an invaluable tool in the field by allowing secure, real-time reporting of sample collection and results.

Assessment of PM2.5 monitoring using MicroPEM: A validation study in a city with elevated PM2.5 levels

Portable monitors such as MicroPEM can accurately characterize personal exposure of pollutants, which is critical for linking exposure and health effects of air pollution. The RTI (RTI International, Research Triangle Park, NC, USA) MicroPEM V3.2A provides both real-time fine particulate matter (PM2.5) concentrations and time-integrated PM samples collected onto Teflon filters that can be used to correct real-time data as well as allow further lab chemical analysis of species on filters (e.g., metal, black carbon). Due to the optical reflectivity of local PM sources can be very different from available standard reference particles used for calibration by RTI, there is a need for gravimetric correction and validation at each study location. However, assessments of MicroPEM have been limited in locations with severe air pollution, such as Beijing. We selected a variety of weather and air quality conditions, including both clear and hazy days in Beijing, to compare PM2.5 data among MicroPEMs as well as between MicroPEM and other types of samplers. We also compared MicroPEM real-time PM2.5 concentrations with data from nearby fixed-sites. The results show MicroPEM performed well across a wide range of PM2.5 concentrations (6–461 μg/m3) and MicroPEM data, after gravimetric correction, were consistent with those from moderate-volume samplers. Good agreement was also found between real-time data from MicroPEM and fixed-site data. The present study covered a wide range of pollution levels in actual environments and validated the usage of MicroPEM as a PM2.5 monitor in locations with elevated PM2.5 levels.

Evaluation of Filter Media Options for High Volume PM2.5 Sampling

Abstract. Polytetrafluoroethylene (PTFE), glass fiber, and cellulose fiber filter media were evaluated under controlled conditions to determine their suitability for high volume PM2.5 sampling. Repeated mounting and unmounting events of new filters not exposed to ambient particulate matter were conducted in a laboratory environment and differences in the filter weight recorded. After the initial mounting and unmounting event, the filters exhibited weight changes of -2.24 mg, -0.61 mg, and 0.18 mg for cellulose, PTFE, and glass fiber filters, respectively. The standard deviation of replicated measurements after the first event was 1.76 (n = 9), 0.50 (n = 10), and 0.31 (n = 10) for cellulose, PTFE, and glass fiber filters, respectively. The combination of weight loss and standard deviation made the cellulose filter unsuitable for use in high volume PM2.5 samplers. However, improved performance over PTFE filters, suggests that glass fiber filters similar in specification to PTFE filters should be considered as acceptable substitutes in high volume PM2.5 sampling. Keywords: Air quality, Error, Filters, Measurement, Particles, Sampling technique.

Measurements of I/SVOCs in biomass-burning smoke using solid-phase extraction disks and two-dimensional gas chromatography

Abstract. Biomass-burning organic-aerosol (OA) emissions are known to exhibit semi-volatile behavior that impacts OA loading during plume transport. Because such semi-volatile behavior depends in part on OA composition, improved speciation of intermediate and semi-volatile organic compounds (I/SVOCs) emitted during fires is needed to assess the competing effects of primary OA volatilization and secondary OA production. In this study, 18 laboratory fires were sampled in which a range of fuel types were burned. Emitted I/SVOCs were collected onto Teflon filters and solid-phase extraction (SPE) disks to qualitatively characterize particulate and gaseous I/SVOCs, respectively. Derivatized filter extracts were analyzed using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS). Quality control tests were performed using biomass-burning relevant standards and demonstrate the utility of SPE disks for untargeted analysis of air samples. The observed chromatographic profiles of I/SVOCs in coniferous fuel-derived smoke samples were well correlated with each other, but poorly correlated with other fuel types (e.g., herbaceous and chaparral fuels). Emissions of benzenediol isomers were also shown to be fuel dependent. The combined Teflon and SPE filter data captured differences in gas-particle partitioning of the benzenediol isomers, with hydroquinone having a significantly higher particle-phase fraction than catechol due to its lower volatility. Additionally, the speciated volatility distribution of I/SVOCs in smoke from a rotten-log fire was estimated to evaluate the composition of potentially volatilized primary OA, which was entirely attributed to oxygenated (or other heteroatomic) compounds. The isomer-dependent partitioning and the speciated volatility distributions both suggest the need for better understanding of gas-phase and heterogenous reaction pathways of biomass-burning-derived I/SVOCs in order to represent the atmospheric chemistry of smoke in models.

Analysis of polyhalogenated carbazoles in sediment using liquid chromatography–tandem mass spectrometry

The purpose of this study was to develop a novel and sensitive method for the analysis of carbazole and polyhalogenated carbazoles (PHCs) in sediment using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Briefly, 5.0 g of freeze-dried sediment samples were extracted with dichloromethane using pressurized liquid extraction (PLE). The extract was purified with Florisil solid phase extraction cartridge, filtered through 0.22 µm polytetrafluoroethylene filter using a glass syringe, followed by LC-MS/MS analysis. Besides parameters for LC-MS/MS analysis, sample preparation procedures (including solvents for PLE, sorbents for cleanup, and filters for sample filtration) were optimized. The limits of detection and limits of quantification of target compounds were in the ranges of 3.0 × 10−3 to 0.22 ng g−1 dry weight (d.w.) and 1.0 × 10−2 to 0.75 ng g−1 d.w., respectively. The recoveries of target compounds in the spiked sediments at 2.0 ng g−1 d.w. and 10 ng g−1 d.w. were 64.8–91.8% and 70.9–124.7%, respectively, with relative standard deviations being less than 13.2%. Except that 36-BCZ had positive matrix effects of 63.3%, the sediment matrices generally displayed low or medium negative matrix effects on the other target compounds during LC-MS/MS analysis. The developed method was applied in the analysis of carbazoles and PHCs in sediment samples from Jiulong River, Fujian, China and all the target compounds were detected in the samples.

Carbonaceous aerosol sampling of gasoline direct injection engine exhaust with an integrated organic gas and particle sampler

Positive and negative artifacts of particle-phase organic carbon (p-OC) and the polycyclic aromatic hydrocarbons (PAHs) in gasoline direct injection (GDI) engine exhaust particulate matter (PM) were assessed using an integrated organic gas and particle sampler (IOGAPS). Three configurations (denuder + sorbent impregnated filters (SIFs), upstream Zefluor filter + denuder + SIFs, and standard filter pack + SIFs) were used to collect GDI exhaust samples at cold start and highway cruise operating conditions with no aftertreatment. Approximately 35% of the measured GDI p-OC was attributed to positive artifacts; negative artifacts were not detectable due to low overall SVOC concentrations. GDI engine exhaust PAH concentrations were approximately 10 times higher during cold start than highway cruise. At highway cruise, pyrene and fluoranthene were the dominant PAHs in the undenuded filter pack; downstream of the denuder benzo(a)anthracene was the dominant PAH. From a comparison of our findings to published PAH emission factors we estimate that three-way catalyst conversion efficiencies of PAHs were approximately 80% for 3 of the 15 PAHs measured during highway cruise operation. These conversion efficiencies may be considerably lower during cold start operation when the three-way catalyst has not reached its operating temperature. Our previous work showed that adverse biological responses to GDI engine exhaust exposure may be dominated by the particle phase when measured downstream of a Teflon filter. Understanding the partitioning characteristics of PAHs may help elucidate specific PAHs contributing to this effect.

Emissions from village cookstoves in Haryana, India, and their potential impacts on air quality

Abstract. Air quality in rural India is impacted by residential cooking and heating with biomass fuels. In this study, emissions of CO, CO2, and 76 volatile organic compounds (VOCs) and fine particulate matter (PM2.5) were quantified to better understand the relationship between cook fire emissions and ambient ozone and secondary organic aerosol (SOA) formation. Cooking was carried out by a local cook, and traditional dishes were prepared on locally built chulha or angithi cookstoves using brushwood or dung fuels. Cook fire emissions were collected throughout the cooking event in a Kynar bag (VOCs) and on polytetrafluoroethylene (PTFE) filters (PM2.5). Gas samples were transferred from a Kynar bag to previously evacuated stainless-steel canisters and analyzed using gas chromatography coupled to flame ionization, electron capture, and mass spectrometry detectors. VOC emission factors were calculated from the measured mixing ratios using the carbon-balance method, which assumes that all carbon in the fuel is converted to CO2, CO, VOCs, and PM2.5 when the fuel is burned. Filter samples were weighed to calculate PM2.5 emission factors. Dung fuels and angithi cookstoves resulted in significantly higher emissions of most VOCs (p&lt;0.05). Utilizing dung–angithi cook fires resulted in twice as much of the measured VOCs compared to dung–chulha and 4 times as much as brushwood–chulha, with 84.0, 43.2, and 17.2 g measured VOC kg−1 fuel carbon, respectively. This matches expectations, as the use of dung fuels and angithi cookstoves results in lower modified combustion efficiencies compared to brushwood fuels and chulha cookstoves. Alkynes and benzene were exceptions and had significantly higher emissions when cooking using a chulha as opposed to an angithi with dung fuel (for example, benzene emission factors were 3.18 g kg−1 fuel carbon for dung–chulha and 2.38 g kg−1 fuel carbon for dung–angithi). This study estimated that 3 times as much SOA and ozone in the maximum incremental reactivity (MIR) regime may be produced from dung–chulha as opposed to brushwood–chulha cook fires. Aromatic compounds dominated as SOA precursors from all types of cook fires, but benzene was responsible for the majority of SOA formation potential from all chulha cook fire VOCs, while substituted aromatics were more important for dung–angithi. Future studies should investigate benzene exposures from different stove and fuel combinations and model SOA formation from cook fire VOCs to verify public health and air quality impacts from cook fires.

Assessment of in vitro inhalation bioaccessibility of airborne particle‒bound potentially toxic elements collected using quartz and PTFE filter

Atmospheric particulate matters (TSP and PM2.5) were sampled using quartz fiber filters and polytetrafluoroethylene (PTFE) filters, respectively. Particles deposited on the filters were characterized by a scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) and an attenuated total reflection FT-IR spectroscopy (ATR-FT-IR). The in vitro inhalation bioaccessibility of TSP- and PM2.5-bound potentially toxic elements (PTEs) on the quartz fiber and PTFE filters with different physico-chemical properties were extracted by four kinds of in vitro inhalation bioaccessibility procedures. SEM-EDX spectra under different magnifications show the heterogeneous distribution and agglomeration of PM2.5 collected on the quartz fiber filter and PTFE filter. Results of ATR-FT-IR show different surface functional groups of PM2.5 deposited on quartz fiber and PTFE filters. 24 h was the optimal interval time for the analyses of in vitro inhalation bioaccessibility of TSP-bound PTEs. The in vitro inhalation bioaccessibility of TSP- and PM2.5‒bound PTEs varied greatly among four in vitro inhalation bioaccessibility procedures. The in vitro inhalation bioaccessibility of TSP- and PM2.5‒bound PTEs didn't show strong dependence on the quartz fiber filters and PTFE filters with different properties. The in vitro inhalation bioaccessibility procedures have greater influence on the in vitro inhalation bioaccessibility of particle-bound PTEs than the kinds of the sampling filters.

Exposure to Fine Particles and PAHs in Pizza Restaurants with Wood-Fired Ovens

IntroductionSome restaurants use wood-fired ovens for cooking and baking, e.g. pizzerias. The aim was to measure exposure to fine particles for the workers and in the restaurants.MethodsMeasurements were performed at seven restaurants (2 days, 8 hr). The ovens were located in a working area in the restaurants. Personal exposure to fine particles (PM2.5) and particulate polycyclic aromatic hydrocarbons (PAHs) were measured on two workers at each restaurant. PM2.5 was collected on teflon filter. Mass concentration was determined gravimetrically and analyzed for PAHs using GC-MS in SIR mode. One of the workers also wore a personal sampler for black carbon (BC), MicroAeth Model AE51. Stationary sampling equipment were placed near the oven and near the dining tables. In addition, size-fractioned particle samples (five size ranges including &amp;gt;2.5, 1.0-2.5, 0.50-1.0, 0.25-0.50, and &amp;lt; 0.25 µm) were collected near the oven using a Sioutas Cascade Impactor. Particle number concentration (PNC), 10-1000 nm, was measured with a Condensation Particle Counter (CPC3007).ResultsMedian personal exposure to PM2.5 and B(a)P for 26 workers were 27 µg/m3 (range: 13-76 µg/m3) and 0.13 ng/m3 (range: 0.01-2.6 ng/m3), respectively. Stationary levels were similar to personal exposure. No significant difference was found between concentrations near the ovens and the dining area. The majority of the B(a)P (&amp;gt;95%) was found in the two finer stages (0.25-0.50, and &amp;lt;0.25 µm). Out of that, in average 78% was found in the finest stage. Median BC exposure varied between 0.5 and 4.1 µg/m3 and was higher during lunch and evening rush hours. The PNC varied across a wide range between the restaurants, with means from about 20 000 up to 170 000 part/cm3.ConclusionsThe exposure to B(a)P were well below OEL. Almost all B(a)P was associated with PM0.25. Particles generated from the wood-fired ovens gave rise to high number concentrations; however, the measured particles mass concentrations were low.

Association of PM2.5 of Outdoor Origin with Biomarkers of Oxidative Stress in COPD Patients

Introduction: Studies have shown effects of ambient particulate matter &amp;#8804; 2.5 microns in diameter (PM2.5) on oxidative stress biomarkers; however, less is known of these effects indoors in patients with chronic obstructive pulmonary disease (COPD). In this study, we assessed the association between indoor PM2.5 apportioned into indoor and outdoor origin and biomarkers of oxidative stress.Methods: We recruited 82 men with COPD who ran a micro-environmental sampler in their home for 1 week up to 4 times a year (n&amp;#61;225 samples). Teflon filter samples were analyzed gravimetrically for indoor PM2.5, and outdoor PM2.5 was measured at a central site. Daily indoor PM2.5 was calculated and apportioned into indoor (PMin) and outdoor origin (PMout) using the indoor-outdoor sulfur ratio as a surrogate for infiltration. Urine samples were obtained for analysis of 8-OHdG and malondialdehyde (MDA). We fit mixed effects models with a random intercept for each participant and adjusted for age, race, season, time of urine collection, BMI, creatinine, diabetes, heart disease, indoor nitrogen dioxide, ambient temperature, and relative humidity.Results: We observed suggestive effects of total PM2.5 on 8-OHdG, with the strongest effect on the 1 day lag (3.6% increase per IQR, 95% CI: -0.69-8.2). For MDA, there were statistically significant effects of total PM2.5 with longer moving averages (strongest effect on the 1-7 day moving average: 6.5% per IQR, 95% CI: 0.88-12.4). Effects of PMout across time windows displayed similar yet stronger patterns compared to total PM2.5, with the greatest effects on the 1 day lag (16.7% per IQR, 95% CI: 1.8-33.7) for 8-OHdG and the 1-7 day moving average (19.3% per IQR, 95% CI: -0.9-43.6) for MDA. There were no statistically significant effects of PMin.Conclusions: Our results suggest that indoor infiltration of PM2.5 of outdoor origin is positively associated with increased lipid peroxidation (MDA) and DNA oxidation (8-OHdG) in patients with COPD.

Association between cancer risk and polycyclic aromatic hydrocarbons' exposure in the ambient air of Ahvaz, southwest of Iran.

Nowadays, a large number of health endpoints such as disease rates, treatment costs, and death, by air pollutants, have been a serious health problem for humans. One of the most hazardous air pollutants, which is highly dangerous for human health, is polycyclic aromatic hydrocarbons (PAHs). The existence of the emission of industries' pollutants and seasonal variations are the primary agents affecting PAHs' concentration. The purposes of this study were to calculate the cancer risk and measure PAHs' exposure in the ambient air of Ahvaz, southwest of Iran, during 2017. Three distinct areas ((S1) industrial, (S2) high traffic, and (S3) residential) of Ahvaz metropolitan were selected. Omni sampler equipped with polytetrafluoroethylene (PTFE) filters were used for active sampling of PAHs. To detect the level of PAHs, gas chromatography with mass spectrometry (GC/MS) was used. Incremental lifetime cancer risk (ILCR) and lifetime average daily dose (LADD) were used to estimate the health risk caused by PAHs. The results showed that the residential and industrial areas had the lowest and highest level of PAHs. Moreover, the average levels of PAHs in industrial, high traffic, and residential areas were 8.44 ± 3.37, 7.11 ± 2.64, and 5.52 ± 1.63ngm-3, respectively. Furthermore, ILCR in autumn and winter was higher than EPA standard, 0.06307 and 0.04718, respectively. In addition, ILCR in different areas was significantly higher than standard. Research findings imply that the levels of exposure to PAHs can increase ILCR and risk of health endpoint. The cancer risk attributed to PAHs should be further investigated from the perspective of the public health in metropolitans.

Optimisation of protocol for effective detachment and selective recovery of the representative bacteria for extraction of metagenomic DNA from Eucalyptus spp. woodchips

For some environments such as planktonic/aqueous environments, the separation of bacteria cells from eukaryotic cells prior to DNA extraction using filtration is relatively straightforward. However, for woodchips, the bacteria are attached/embedded within the wood matrix, which prevents easy removal of bacterial cells. In this study, a method for the selective extraction of DNA from bacteria inhabiting Eucalyptus spp. woodchips has been developed. The objective was to compare milled and unmilled woodchips processed via three detachment methods, viz., sonication, vortexing and shaking followed by filtration using Teflon filters according to three relevant criteria: DNA yield, DNA purity and quality of DNA. Highest DNA yield was obtained by milling and vortexing for 10 min (77.50 ± 5.17 ng/μl), followed by milling and vortexing for 2 min (61.00 ± 6.56 ng/μl), unmilled and vortexing for 10 min (38.67 ± 5.17 ng/μl) and milled and shaking for 2 h (31.62 ± 5.17 ng/μl). The lowest DNA yield was obtained by using unmilled woodchips and 5 min of sonication treatment (7.00 ± 1.22 ng/μl). There was no significant difference in DNA purity for milled or unmilled woodchips processed via the three detachment methods. Duration of cell detachment treatment did not significantly influence DNA yield and purity. Following optimisation experiments, it was possible to extract bacterial DNA using milled woodchips and 10 minute vortexing devoid of DNA from the host background and other associated eukaryotes and of sufficient quality and quantity for metagenomic analysis.

Characterization of Fine Particulate Matter in Sharjah, United Arab Emirates Using Complementary Experimental Techniques

Airborne particulate matter (PM) pollutants were sampled from an urban background site in Sharjah, United Arab Emirates. The fine fraction (PM2.5) (particulates with aerodynamic diameters of less than 2.5 μm) was collected on 47-mm Teflon filters and analyzed using a combined set of non-destructive techniques in order to provide better understanding of the sources of pollutants and their interaction during transport in the atmosphere. These techniques included gravimetric analysis, equivalent black carbon (EBC), X-ray fluorescence, scanning electron microscopy, and X-ray diffraction. Generally, the PM2.5 concentrations are within the limits set by the World Health Organization (WHO) and the United States (US) Environmental Protection Agency. The EBC content is in the range of 10–12% of the total PM concentration (2–4 µg m−3), while S (as ammonium sulfate), Ca (as calcite, gypsum, and calcium carbonate), Si (as quartz), Fe, and Al were the major sources of PM pollution. EBC, ammonium sulfate, Zn, V, and Mn originate from anthropogenic sources such as fossil fuel burning, traffic, and industrial emissions. Natural elements such as Ca, Fe, Al, Si, and Ti are due to natural sources such as crustal materials (enhanced during dust episodes) and sea salts. The average contribution of natural sources in the total PM2.5 mass concentration over the sampling period is about 40%, and the contribution of the secondary inorganic compounds is about 27% (mainly ammonium sulfate in our case). The remaining 22% is assumed to be secondary organic compounds.

PRESENCE STATE OF TRACE ELEMENTS IN THE OHTAKIGAWA RIVER WATERSHED FROM THE FOOT OF Mt. ONTAKE

This paper is aimed at understanding the influence of Mt. Ontake volcanic activity on the water quality of the Ohtakigawa River watershed. For this purpose, various properties of trace elements are obtained. The Ohtakigawa, which flows along the southern foot of Mt. Ontake, has several tributaries such as Nigorigawa River, Shirakawa River, Shimokurosawa River, and Uguigawa River. Seven sampling stations were selected in the four tributaries (four points) and the Ohtakigawa (three points). Filtration of samples wascarried out with teflon filter paper (PTFE, 0.5μm, φ 47mm), and the samples were separated into dissolved and suspended matters. Trace elements contained in them were analyzed by using the ICPE. The concentrations of the trace elements were high in the following order: the Nigorigawa (Al: 6.16mg L-1), the Ohtakigawa after the confluence of the Nigorigawa (Al: 1.92mg L-1 and 0.88mg L-1), and the others (Al: 0.06-0.70mg L-1). This result indicates that among the four tributaries, the Nigorigawa plays a predominantrole in the change in the water quality of the Ohtakigawa.

Demonstrating PM2.5 and road-side dust pollution by heavy metals along Thika superhighway in Kenya, sub-Saharan Africa.

This study assessed the level of heavy metal in roadside dust and PM2.5 mass concentrations along Thika superhighway in Kenya. Thika superhighway is one of the busiest roads in Kenya, linking Thika town with Nairobi. Triplicate road dust samples collected from 12 locations were analysed for lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), and copper (Cu) using atomic absorption spectrophotometry (AAS). PM2.5 samples were collected on pre-weighed Teflon filters using a BGI personal sampler and the filters were then reweighed.The ranges of metal concentrations were 39-101μg/g for Cu, 95-262μg/g for Zn, 9-28μg/g for Cd, 14-24μg/g for Ni, 13-30μg/g for Cr, and 20-80μg/g for Pb. The concentrations of heavy metals were generally highly correlated, indicating a common anthropogenic source of the pollutants. The results showed that the majority of the measured heavy metals were above the background concentration, and in particular, Cd, Pb, and Zn levels indicated moderate to high contamination. Though not directly comparable due to different sampling timeframes (8h in this study and 24h for guideline values), PM2.5 for all sites exceeds the daily WHO PM2.5 guidelines of 25μg/m3. This poses a health risk to people using and working close to Thika superhighway, for example, local residents, traffic police, street vendors, and people operating small businesses. PM2.5 levels were higher for sites closer to Nairobi which could be attributed to increased vehicular traffic towards Nairobi from Thika. This study provides some evidence of the air pollution problem arising from vehicular traffic in developing parts of the world and gives an indication of thepotential health impacts. It also highlights the need for source apportionment studies to determine contributions of anthropogenic emissions to air pollution, as well as long-term sampling studies that can be used to fully understand spatiotemporal patterns in air pollution within developing regions.

Airborne protein concentration: a key metric for type 1 allergy risk assessment\u2014in home measurement challenges and considerations

BackgroundExposure to airborne proteins can be associated with the development of immediate, IgE-mediated respiratory allergies, with genetic, epigenetic and environmental factors also playing a role in determining the likelihood that sensitisation will be induced. The main objective of this study was to determine whether airborne concentrations of selected common aeroallergens could be quantified in the air of homes using easily deployable, commercially available equipment and analytical methods, at low levels relevant to risk assessment of the potential to develop respiratory allergies. Additionally, air and dust sampling were compared and the influence of factors such as different filter types on allergen quantification explored.MethodsLow volume air sampling pumps and DUSTREAM® dust samplers were used to sample 20 homes and allergen levels were quantified using a MARIA® immunoassay.ResultsIt proved possible to detect a range of common aeroallergens in the home with sufficient sensitivity to quantify airborne concentrations in ranges relevant to risk assessment (Limits of Detection of 0.005–0.03 ng/m3). The methodology discriminates between homes related to pet ownership and there were clear advantages to sampling air over dust which are described in this paper. Furthermore, in an adsorption–extraction study, PTFE (polytetrafluoroethylene) filters gave higher and more consistent recovery values than glass fibre (grade A) filters for the range of aeroallergens studied.ConclusionsVery low airborne concentrations of allergenic proteins in home settings can be successfully quantified using commercially available pumps and immunoassays. Considering the greater relevance of air sampling to human exposure of the respiratory tract and its other advantages, wider use of standardised, sensitive techniques to measure low airborne protein concentrations and how they influence development of allergic sensitisation and symptoms could accelerate our understanding of human dose–response relationships and refine our knowledge of thresholds of allergic sensitisation and elicitation via the respiratory tract.

Ambient aerosol composition by infrared spectroscopy and partial least squares in the chemical speciation network: Multilevel modeling for elemental carbon

ABSTRACTFourier transform infrared spectroscopy (FT-IR) has been used to predict elemental carbon (EC) on polytetrafluoroethylene (PTFE) filter samples from the United States Environmental Protection Agency's Chemical Speciation Network (CSN). This study provides a proof-of-principle demonstration of using multilevel modeling to determine thermal/optical reflectance (TOR) equivalent EC (a.k.a., FT-IR EC) on PTFE samples collected in the CSN. Initially, spectra from nine geographically disperse sites were pooled and calibrated directly to collocated TOR EC measurements. The FT-IR EC quantified in test samples was deemed substandard when judged against an earlier study, e.g., R2 = 0.760 and median absolute deviation (MAD) = 26.7%. Upon scrutinizing each sample's absolute prediction error and squared Mahalanobis distance, Elizabeth, NJ predictions were found to exhibit atypical systematic errors, motivating the development of a multilevel classification and calibration procedure. Atypical Elizabeth spectra w...