Ralph E. Baumgardner

Contribution of woodsmoke and motor vehicle emissions to ambient aerosol mutagenicity

A multiple linear regression form of receptor modeling has been used to determine the sources of the mutagenicity (a measure of potential carcinogenicity) of fine-particle ambient aerosol samples collected during the winter in a residential area of Albuquerque, NM. Virtually all the mutagenicity (Salmonella typhimurium TA98 +S9) could be accounted for by woodsmoke and motor vehicle emissions. Woodsmoke was found to be the greater contributor to the average ambient concentrations of both extractable organics and mutagenicity. The mutagenic potency (revertants per microgram) of extractable organics traced to motor vehicles, however, was 3 times greater than that with a woodsmoke origin. The results were confirmed by 14C measurements.

Cloud chemistry in the eastern United States, as sampled from three high-elevation sites along the Appalachian Mountains

Abstract Atmospheric deposition of acidic cloud water is thought to be one of the causes for the recent forest decline in industrialized areas of the world. The present paper presents results from the Mountain Acid Deposition Program (MADPro), a part of EPAs Clean Air Status and Trends Network, (CASTnet). We used automated cloud water collectors at three selected mountain sites (Whiteface Mt., NY; Whitetop Mt., VA; and Clingmans Dome, TN) to take hourly samples from non-precipitating clouds during temperate (non- freezing) seasons of each year from 1994 to 1997. Samples were promptly analyzed for pH, conductivity, and concentration of dissolved ions. Cloud liquid water content (LWC) and meteorological parameters were measured at each site. Mean cloud frequencies and LWC of clouds were higher at Whiteface Mt., NY, than in the Southern Appalachians. The four most prevalent ions found in cloud water samples were usually, in order of decreasing concentration: sulfate ( SO 2− 4 ) hydrogen (H + ), ammonium (NH 4 + ), and nitrate (NO 3 − ). Within cloud events the concentration of these major ions tended to co-vary. Typically there was an inverse relationship between LWC of the cloud and ionic concentration of the cloud water. During the sampling season, the highest ionic concentrations were seen during mid-summer. Ionic concentrations of samples from the southern sites were significantly higher than samples from Whiteface Mt., but further analysis indicates that this is at least partially due to the north–south difference in the LWC of clouds. MADPro results are shown to be comparable with previous studies of cloud chemistry in North America.

Evaluation of improved inlets and annular denuder systems to measure inorganic air pollutants

Abstract Modifications were made to various components of an annular denuder system for the collection of ambient SO2, HNO3, HNO2, NH3, SO42−, and NO3−. The annular denuder was modified to incorporate a laminar restoration section as part of the annular denuder itself in order to reduce construction costs and to minimize leaks in the system during field operation. Teflon-coated glass impactors and cyclone inlets for the annular denuders were developed and evaluated for their inertness to acidic gases collected in the annular denuders. Paired samples were collected over a period of several months on the roof of the EPA laboratory in Research Triangle Park, NC, in order to compare the new inlets. For 17 sampling runs when two different types of inlets were compared, average differences for the measurement of SO2, HNO3 and HNO2 were 3.4, 6.4 and 8.3%, respectively. For five sampling runs using pairs of identical impactor inlets, duplication for SO2 and HNO3 improved slightly. Annular denuder systems using cyclone and impactor preseparators yielded no significant differences in their abilities to collect HNO3 and SO2. The results are supported by the laboratory data of Appel et al. (1987, EPA/APCA Symp., Research Triangle Park), which indicate that no HNO3 is retained in the inlets tested. Coarse-particle bounce through the system was shown to be a potential problem, although this had no apparent effect on acidic gas collection.

Dynamic chemical characterization of montane clouds

Abstract Cloud water collections have been made on Mt. Mitchell using a nearly real-time cloud and rain acidity/conductivity (CRAC) analyzer. Results are reported for integrating times of approximately 5 min during several cloud events in the summer and fall of 1987. Both pH and ionic strength during cloud events were found to be much more variable than previously indicated by cloud collection. Maximum values of H + and SO 4 2− ion concentrations in 5-min samples were as much as 2.5 times greater than those measured in 1-h integrated collections. These results are not influenced by instrumental variability to any measurable extent. Results from repeated quality control samples were highly reproducible, and agreement between integrated collection data and the average values of 5-min sequential samples was also very good.

Development of crustal profiles for receptor modeling

Abstract A comprehensive program to sample and analyze soil and street dust was undertaken to develop representative source profiles for use in receptor modeling. Samples of soils and dusts from road surfaces were collected in the Philadelphia area, resuspended, fractionated into fine (

Development of an automated cloud water collection system for use in atmospheric monitoring networks

An automated cloud water collection system for unattended operation at remote sites is described. This system consists of a cloud water collector, sample accumulator, sample storage unit, and electronic control unit. Threshold values for liquid water content, wind speed, and temperature were set with the electronic control unit to initiate automatic collection of cloud water samples. The automated system was tested in the summer of 1994 at two remote sites: Whitetop Mountain, VA, and Whiteface Mountain, NY. During this period, it successfully collected 449 hourly cloud water samples.

Detection of vinyl chloride and related compounds by a gas chromatographic, chemiluminescence technique.

(1) “Particulate Polycyclic Organic Matter”, National Academy of Sciences, Washington, D.C., 1972. (2) Lesko, S. A., Hoffmann, H. D., Ts’o, P.O.P., Maher, V. M., Prog. Mol. Subcell. Biol., 2,347 (1971). ( 3 ) Grover, P., New Sci., 685 (1973). (4) Searle,C. E., Chem. Ind., 111 (1972). (5) Fed. Regist., 36 (247), 24888 (1971). (6) Jones, P. W., “Analysis of Nonparticulate Organic Compounds in Ambient Atmospheres”, presented at the 67th Annual Meeting of the Air Pollution Control Association, Denver, Colo., June 9-13,1974. (7) Bertsch, W., Chang, R. C., Zlatkis, A., J . Chromatogr. Sci., 12, 175 (1974). (8) Dravnieks, A,, Krotaszynski, B. K., Burton, J., O’Donnell, A., Burgwald, T., “High Speed Collection of Organic Vapors from the Atmosphere”, presented at the 11th Conference on Methods in Air Pollution and Industrial Hygiene Studies, Berkeley, Calif., April 1970. (9) Giammar, R. D., Jones, P. W., “Improved Sampling for POM and Particulate Material”, EPA Contract No. 68-02-1409 (Task 4), 1975. (10) Moore, G. G., Thomas, R. S., Monkman, J. L., J . Chroma-

Wedding ambient aerosol sampling inlet for an intermediate flow rate (4 cfm) sampler.

rn An ambient air inlet for an intermediate flow rate sampler has been designed, fabricated, and performance tested. The device is presently designed to operate a t 4 cfm and have an aerodynamic particle size of 10 pm associated with a 50% effectiveness value (D50), which is commensurate with the anticipated changes in the National Ambient Air Quality Standards under consideration by the U.S. Environmental Protection Agency. However, the system can be easily modified to meet any DW value ultimately selected by the Administrator. It is cost effective and potentially more accurate to collect a greater amount of mass than is possible with the current dichotomous sampler in the same 24-h period. Determination of mass may then be performed on a five-place analytical balance. A suitable filter substrate can be employed such as Teflon or microquartz, which do not have an artifact problem as observed with the standard Hi-Vol glass fiber filter. The system is independent of all environmental Conditions, including windspeed and wind direction. The inlet employs a unique, omnidirectional cyclone fractionator. The nature of the cyclonic forces in conjunction with the tortuous pathway that the transmitted particles must follow to reach the exit plane of the inlet precludes the bouncing or reentrainment of particles experienced with all impaction-type devices.

Development and evaluation of an acid-precipitation monitor for fractional event sampling with capability for real-time pH and conductivity measurement

An acid precipitation monitor has been developed that collects fractions of rain events, measures the pH and conductivity in real-time, and stores the remaining samples under refrigerated conditions. A Z-80 microprocessor controls all operations of the monitor including sample collection, sample analysis, quality control analysis, and data recording. Quality control analysis consists of analysis upon demand of a low-ionic-strength solution. The monitor was evaluated in the field and about 40 rain events were monitored. Excellent stability of the pH electrode was found under field conditions.

Intercomparison of Clean Air Status and Trends Network Nitrate and Nitric Acid Measurements with Data from Other Monitoring Programs

Abstract The U.S. Environmental Protection Agency Clean Air Status and Trends Network (CASTNET) utilizes an open-face filter pack system to measure concentrations of atmospheric sulfur and nitrogen species. Concentration data for nitrogen species measured with filter pack systems sometimes deviate from data collected by other measurement systems used to measure the same species. The nature of these differences suggests that more than one sampling mechanism or atmospheric process is involved. The study presented here examines these differences by intercomparing CASTNET data with data from other studies, examining the results from earlier intercomparison studies, and conducting a field test to investigate the effect of particle size on filter pack measurement systems. Measurements of nitrogen species from the Maryland Aerosol Research and Characterization (MARCH) monitoring site were compared with nitrogen concentrations at three nearby CASTNET sites. Results indicate that CASTNET measured higher particulate nitrate (NO3 -) and lower gaseous nitric acid (HNO3) concentrations. Comparisons of NO3 - from 34 collocated CASTNET and Inter-agency Monitoring of Protected Visual Environments (IMPROVE) sites show that CASTNET NO3 - measurements were typically higher than the corresponding IM PROVE values. Also, results from the Lake Michigan Air Director’s Consortium Midwest Ammonia Monitoring Project demonstrated NO3 - dissociation on Teflon filters. To investigate the effect of particle size, filter pack measurement systems were operated at three CASTNET sites with and without cyclones during six 7-day measurement periods from March to August 2006. Results indicate the size-selection cyclones had a significant effect on both NO3 - and HNO3 concentrations, but little effect on sulfate (SO4 2-) and ammonium (NH4 +) levels. NO3 - concentrations sampled with the open-face filters were significantly higher than concentrations measured with a 2.5-μm cut point, as were HNO3 concentrations. Although limited in spatial and temporal coverage, the field study showed that the use of an open-face filter pack may allow for the collection of coarse NO3 - particles and for the reaction of HNO3 with metals/salts on the Teflon filter.