Development of a Sample Equilibration System for the TEOM Continuous PM Monitor

ABSTRACT

In recent years, scientific discussion has included the influence of thermodynamic conditions (e.g., temperature, relative humidity, and filter face velocity) on PM retention efficiency of filter-based samplers and monitors. Method-associated thermodynamic conditions can, in some instances, dramatically influence the presence of particle-bound water and other light-molecular-weight chemical components such as particulate nitrates and certain organic compounds. The measurement of fine particle mass presents a new challenge for all PM measurement methods, since a relatively greater fraction of the mass is semi-volatile.

The tapered element oscillating microbalance (TEOM) continuous PM monitor is a U.S. Environmental Protection Agency (EPA) PM₁₀ equivalent method (EQPM-1090-079). Several hundred of these monitors are deployed throughout the United States. The TEOM monitor has the unique characteristic of providing direct PM mass measurement without the calibration uncertainty inherent in mass surrogate methods. In addition, it provides high-precision, near-real-time continuous data automatically. Much attention has been given to semi-volatile species retention of the TEOM method.

While using this monitor, it is desirable to maintain as low an operating temperature as practical and to remove unwanted particle-bound water. A new sample equilibration system (SES) has been developed to allow conditioning of the PM sample stream to a lower humidity and temperature level. The SES incorporates a special low-particle-loss Nafion dryer. This paper discusses the configuration and theory of the SES. Performance results include high time-resolved PM_2.5 data comparison between a 30 °C sample stream TEOM monitor with SES and a standard 50 °C TEOM monitor. In addition, 24-hr integrated data are compared with data collected using an EPA PM_2.5 Federal Reference Method (FRM)-type sampler. The SES is a significant development because it can be applied easily to existing TEOM monitors.     

Exposure of Chronic Obstructive Pulmonary Disease Patients to Particulate Matter: Relationships between Personal and Ambient Air Concentrations

ABSTRACT

Most time-series studies of particulate air pollution and acute health outcomes assess exposure of the study population using fixed-site outdoor measurements. To address the issue of exposure misclassification, we evaluate the relationship between ambient particle concentrations and personal exposures of a population expected to be at risk of particle health effects.

Sampling was conducted within the Vancouver metropolitan area during April-September 1998. Sixteen subjects (non-smoking, ages 54-86) with physician-diagnosed chronic obstructive pulmonary disease (COPD) wore personal PM_{2 5} monitors for seven 24-hr periods, randomly spaced approximately 1.5 weeks apart. Time-activity logs and dwelling characteristics data were also obtained for each subject. Daily 24-hr ambient PM₁₀ and PM_2.5 concentrations were measured at five fixed sites spaced throughout the study region. SO₄ ^2-, which is found almost exclusively in the fine particle fraction and which does not have major indoor sources, was measured in all PM_{2 5} samples as an indicator of accumulation mode particu-late matter of ambient origin.     

Combined PCDD/F Destruction and Particulate Control in a Baghouse: Experience with a Catalytic Filter System at a Medical Waste Incineration Plant

ABSTRACT

Phoenix Services, Inc., owns and operates the Baltimore Regional Medical Waste Incinerator in Baltimore, MD. New regulations for dioxins and furans imposed a limit that was considerably below historical emission levels. To determine a method to comply with the new dioxin/furan regulations, Phoenix Services performed trials with powdered activated carbon (PAC). Although the results with carbon were acceptable, Phoenix Services decided to replace their woven fiberglass filter bags with catalytic filters that simultaneously destroy dioxins and furans and collect particulate matter (PM). The catalytic filter system offered several advantages to Phoenix Services, including destruction of dioxins and furans instead of adsorption on carbon. The catalytic filters also offered a passive solution that did not require new carbon injection equipment. In January 2000, a campaign to measure dioxins/furans and PM was undertaken.     

A Cost-Effective Weighing Chamber for Particulate Matter Filters

ABSTRACT

Particulate matter (PM) is a ubiquitous air pollutant that has been receiving increasing attention in recent years due in part to the association between PM and a number of adverse health outcomes, including mortality and increases in emergency room visits and respiratory symptoms, as well as exacerbation of asthma and decrements in lung function.^1-5 As a result, the ability to accurately sample ambient PM has become important, both to researchers and to regulatory agencies. The federal reference method for the determination of fine PM as PM_2.5 in the atmosphere recommends that particle-sampling filters be conditioned and weighed in an environment with constant temperature and relative humidity (RH).⁶ It is also recommended that vibration, electrostatic charges, and contamination of the filters from laboratory air be minimized to reduce variability in filter weight measurements. These controls have typically been maintained in small, environmentally controlled “cleanrooms.” As an alternative to constructing an elaborate cleanroom, we have designed, and presented in this paper, an inexpensive weighing chamber to maintain the necessary level of humidity control.     

Role of black carbon in the distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans in aged field-contaminated soils

Floodplain soils containing elevated levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were collected from several locations along the Tittabawassee River (Michigan, USA). The PCDD/F profiles of these soils exhibited distinct congener patterns consistent with byproducts from either chloralkali manufacturing or chlorophenols productions. Black carbon (BC) particles were isolated for the first time from floodplain soil impacted by PCDD/Fs. Petrographic analysis showed that BC particles, including coal, oxidized coal, metallurgical coke, depositional carbon, coal tar/pitch, cenosphere, and charcoal, comprised approximately 30% by volume of the organic fraction with size range of 250 μm-2000 μm from a typical floodplain soil. The BC particles with anthropogenic origin such as pitch and coke associated with the chloralkali production process served as both the source and subsequent transporter for the highly hydrophobic PCDD/Fs. These anthropogenic BC particles were enriched with high levels of PCDFs, containing approximately 1000-fold the concentration found in the bulk soil. The strong association of PCDD/Fs with anthropogenic BC directly impacts the physicochemical and biological availability thus the risk associated with these hydrophobic organochlorines in soils and sediments.     

Fate and effects of anthropogenic chemicals in mangrove ecosystems: a review

The scientific literature for fate and effects of non-nutrient contaminant concentrations is skewed for reports describing sediment contamination and bioaccumulation for trace metals. Concentrations for at least 22 trace metals have been reported in mangrove sediments. Some concentrations exceed sediment quality guidelines suggesting adverse effects. Bioaccumulation results are available for at least 11 trace metals, 12 mangrove tissues, 33 mangrove species and 53 species of mangrove-habitat biota. Results are specific to species, tissues, life stage, and season and accumulated concentrations and bioconcentration factors are usually low. Toxicity tests have been conducted with 12 mangrove species and 8 species of mangrove-related fauna. As many as 39 effect parameters, most sublethal, have been monitored during the usual 3 to 6 month test durations. Generalizations and extrapolations for toxicity between species and chemicals are restricted by data scarcity and lack of experimental consistency. This hinders chemical risk assessments and validation of effects-based criteria.     

Effects of the synthetic pyrethroid insecticide, permethrin, on two estuarine fish species

Limited toxicity data are available for estuarine and marine species and the widely used pyrethroid insecticide, permethrin. This study determined acute effects of permethrin on survival, lipid peroxidation, acetylcholinesterase activity, and splenocyte proliferation for two fish species found in South Carolina estuaries; juvenile red drum (Sciaenops ocellatus) and adult mummichog (Fundulus heteroclitus). Juvenile S. ocellatus were significantly more sensitive than adult F. heteroclitus to permethrin exposure, with a 96-h LC50 value of 8 μg/L determined for red drum compared to 23 μg/L for mummichog. Lipid peroxidation activity of the liver increased in permethrin-treated fish compared to control animals after 24 h and decreased after 96 h. Permethrin had no effect on acetylcholinesterase activity of the brain at the concentrations tested. Permethrin exposure significantly inhibited splenocyte proliferation, indicating an immunosuppressive effect. Most of the effects of permethrin on fish cellular stress enzymes and survival occurred at concentrations much higher than those typically measured in the environment. However, inhibition of splenocyte proliferation in juvenile red drum occurred at approximately twice that of measured permethrin concentrations in surface water. These findings may prove useful to the future management and regulation of pyrethroid insecticide use near estuarine habitats.     

Atmospheric fate of non-volatile and ionizable compounds

A modified version of the Multimedia Activity Model for Ionics MAMI, including two-layered atmosphere, air-water interface partitioning, intermittent rainfall and variable cloud coverage was developed to simulate the atmospheric fate of ten low volatility or ionizable organic chemicals. Probabilistic simulations describing the uncertainty of substance and environmental input properties were run to evaluate the impact of atmospheric parameters, ionization and air-water (or air-ice) interface enrichment.The rate of degradation and the concentration of OH radicals, the duration of dry and wet periods, and the parameters describing air-water partitioning (K_AW and temperature) and ionization (pK_a and pH) are the key parameters determining the potential for long range transport. Wet deposition is an important removal process, but its efficiency is limited, primarily by the duration of the dry period between precipitation events.Given the underlying model assumptions, the presence of clouds contributes to the higher persistence in the troposphere because of the capacity of cloud water to accumulate and transport non-volatile (e.g. 2,4-D) and surface-active chemicals (e.g. PFOA). This limits the efficiency of wet deposition from the troposphere enhancing long-range transport.     

Assessing inter-laboratory comparability and limits of determination for the analysis of cyclic volatile methyl siloxanes in whole Rainbow Trout (Oncorhynchus mykiss)

Cyclic volatile methyl siloxanes (cVMS) are high volume production chemicals used in a wide range of industrial and consumer products. Three cVMS compounds (D4, D5, and D6) have and are undergoing environmental risk evaluations in several countries and have been proposed for legal regulation in Canada. As interest in monitoring concentrations of these chemicals in the environment increase, there is a need to evaluate the analytical procedures for cVMS in biological matrices in order to assess the quality of data produced. The purpose of this study was to determine laboratory testing performance for measuring residues of D4, D5, and D6 in a standard set of fish homogenate samples and to estimate limits of determination for each substance. The samples sent to each laboratory consisted of homogenized whole body tissues of hatchery raised rainbow trout which were fed food fortified with D4, D5, and D6 (dosed) and trout that were fed standard food rations (control). The participants analyzed each sample using their analytical method of choice using their own standards and procedures for quantification and quality control. With a few exceptions, participating laboratories generated comparable results for D4, D5, and D6 in both the dosed and control samples having z-scores between 2 and −2. Method detection limits for the whole fish matrix were on average 2.4 ng g⁻¹ ww for D4, 2.3 ng g⁻¹ ww for D5, and 1.8 ng g⁻¹ ww for D6.